i18n(settings): translate the sidecar storage strings

Fills in the 23 keys that came with optional centralized sidecar storage
(settings.sections.sidecarStorage, the 18 settings.sidecarStorage.*
labels/help/status/confirm strings and the 4
modals.sidecarMigrationConfirm.* titles/button), which the feature PR merged
as [TODO: Translate] copies. No placeholder remains in any locale.

Each locale reuses its own storage-relocation verb rather than a
transliteration of "migration" (ja 移動, ko 이동, ru перенос, matching
settings.folderSettings.recipesPathMigrating), its existing "preview images"
and nav-path renderings, and quotes the migrate button label the way its
other UI-label references do. `.metadata.json`, `.civitai.info` and the
`(<settings dir>/sidecars)` literal stay verbatim.

docs/i18n-translation-guidelines.md gains the "Sidecar storage feature" term
table and pass note, and refreshes the leaf-key count to 2128.

AGENTS.md

@@ -266,6 +266,13 @@ If a cross-layer issue ever needs a live server, the sandboxed helpers live in
   them during migration/import. Never write, modify, or delete them, and never
   propose doing so as a fix — LoRA Manager's own metadata lives in the
   `.metadata.json` sidecar it owns.
+- **Sidecar/preview path derivation must go through `py/utils/sidecar_paths.py`**
+  helpers (never inline `splitext + ".metadata.json"`): the centralized storage
+  mode (`sidecar_storage_mode` / `sidecar_storage_path` settings) relocates
+  `.metadata.json` files and preview images under a mirror tree, so any
+  hand-built path is wrong in that mode. `.civitai.info` stays co-located with
+  the model file in both modes. The new settings keys live only in
+  `DEFAULT_SETTINGS` — `settings.json.example` stays minimal (see below).
 - **`settings.json.example` must stay minimal**: only `use_portable_settings`,
   `civitai_api_key`, and the four core `folder_paths` keys (`loras`,
   `checkpoints`, `unet`, `embeddings`). Do NOT add optional/default keys

docs/i18n-translation-guidelines.md

@@ -4,7 +4,7 @@ This document is the canonical set of conventions for translating LoRA Manager U
 It applies to **human translators and AI agents** alike. Read it before editing anything in
 `locales/`.
 
-Source of truth: `locales/en.json` (10 locales, 2025 leaf keys; all locales share the exact
+Source of truth: `locales/en.json` (10 locales, 2128 leaf keys; all locales share the exact
 same key structure).
 
 Locales: `en`, `zh-CN`, `zh-TW`, `ja`, `ko`, `fr`, `de`, `es`, `ru`, `he` (RTL).
@@ -78,6 +78,23 @@ Locales: `en`, `zh-CN`, `zh-TW`, `ja`, `ko`, `fr`, `de`, `es`, `ru`, `he` (RTL).
 > the `toast.loras.filenameTemplate*` / `toast.settings.filenameTemplates*` toasts. All 9
 > locales are translated (terminology in §2, "Filename Templates feature").
 
+> **Status (2026-09, folder delete verification):** the folder delete modal no longer trusts the
+> sidebar's "empty folder" prediction — it dry-runs the delete against the backend and renders
+> the answer, so a folder whose models are all *excluded* (invisible to the model lists, still
+> real weight files on disk) is refused with an explanation instead of contradicting itself.
+> That added 5 keys (`sidebar.deleteFolderModal.notEmptyMessageCount`,
+> `.notEmptyMessageExcluded`, `.busyTitle`, `.checking`, `sidebar.deleteFolderResult.notEmptyWithCount`);
+> all 9 locales are translated (terminology in §2, "Folder sidebar feature"), so the
+> "no remaining placeholders" claim holds again.
+
+> **Status (2026-09, sidecar storage):** optional centralized storage for `.metadata.json`
+> sidecars and preview images added 23 keys — `settings.sections.sidecarStorage`,
+> the 18 `settings.sidecarStorage.*` labels/help/status/confirm strings, and the 4
+> `modals.sidecarMigrationConfirm.*` titles/button. The pull request merged them as
+> `[TODO: Translate]` copies; all 9 locales are now translated (terminology in §2,
+> "Sidecar storage feature"), so no placeholder remains and the "no remaining placeholders"
+> claim holds again.
+
 ---
 
 ## 1. Hard rules (do not violate)
@@ -391,11 +408,32 @@ The model-root sidebar manages on-disk folders. "Folder" reuses the noun already
 | tree view / list view | zh-CN 树形视图 / 列表视图 · zh-TW 樹狀檢視 / 清單檢視 · ja ツリー表示 / リスト表示 · ko 트리 보기 / 목록 보기 · fr Vue arborescente / Vue liste · de Baumansicht / Listenansicht · es Vista de árbol / Vista de lista · ru Дерево / Список · he תצוגת עץ / תצוגת רשימה |
 | sidebar | reuse each locale's `sidebar.hideOnThisPage` noun: zh-CN 侧边栏 · zh-TW 側邊欄 · ja サイドバー · ko 사이드바 · fr barre latérale · de Seitenleiste · es barra lateral · ru боковая панель · he סרגל צד |
 
-Deleting a folder **never cascades over model files** — the backend refuses it and
+Deleting a folder **never cascades over model files** — the backend refuses it and the
-`sidebar.deleteFolderModal.notEmptyMessage` states the rule in every locale, so keep that
+`sidebar.deleteFolderModal.notEmptyMessage*` keys state the rule in every locale, so keep that
-clause (and its `—`) when the copy is edited. The `{name}` / `{count}` / `{message}` tokens in
+clause (and its `—`) when the copy is edited. The three variants split by what the modal knows:
-`sidebar.createFolderResult.*`, `sidebar.deleteFolderResult.*` and `sidebar.renameFolderResult.*`
+`notEmptyMessage` (no counts), `notEmptyMessageCount` (`{count}`, the blocking models are all
-are verbatim §1-R2 placeholders; `successWithFiles` is the only key carrying `{count}`.
+listed) and `notEmptyMessageExcluded` (`{count}` + `{excluded}`, at least one is hidden by the
+`exclude` flag — the case where the folder legitimately looks empty). `checking` ("Checking the
+folder contents...", ASCII ellipsis) shows while the backend dry run is pending, `busyTitle`
+titles the already-pending-staged-delete state, and `notEmptyWithCount` mirrors
+`deleteFolderResult.notEmpty` with the count for the stale-tree toast.
+
+| Term | Rendering |
+|---|---|
+| excluded from the library | zh-CN 已从模型库中排除 · zh-TW 已從模型庫中排除 · ja ライブラリから除外 · ko 라이브러리에서 제외 · fr exclu de la bibliothèque · de von der Bibliothek ausgeschlossen · es excluido de la biblioteca · ru исключены из библиотеки · he מוחרגים מהספרייה |
+| un-exclude (verb) | zh-CN 取消排除 · zh-TW 取消排除 · ja 除外を解除 · ko 제외를 해제 · fr annuler l'exclusion · de den Ausschluss aufheben · es anular la exclusión · ru снять исключение · he לבטל את ההחרגה |
+| "Manage Excluded Models" quoted in prose | zh-CN “管理已排除的模型” · zh-TW 「管理已排除的模型」 · ja 「除外モデルを管理」 · ko '제외된 모델 관리' · fr « Gérer les modèles exclus » · de „Ausgeschlossene Modelle verwalten“ · es «Gestionar modelos excluidos» · ru «Управление исключёнными моделями» · he «ניהול מודלים מוחרגים» |
+
+A UI label quoted inside prose follows each locale's existing help-text style (zh-CN “ ”,
+zh-TW/ja 「 」, ko ASCII `' '`, fr/ru/es/he « », de „ “) — see `settings.hideEarlyAccessUpdates.help`
+/ `settings.civitaiHost.help` as the precedent. `קובצי מודלים` is the Hebrew model-file noun
+(`notEmptyMessage`); keep it identical in all four Hebrew keys.
+
+The `{name}` / `{count}` / `{excluded}` / `{message}` tokens in `sidebar.createFolderResult.*`,
+`sidebar.deleteFolderResult.*` and `sidebar.renameFolderResult.*` are verbatim §1-R2
+placeholders. The keys carrying `{count}` are `successWithFiles`, `notEmptyMessageCount`,
+`notEmptyMessageExcluded` and `notEmptyWithCount`; `notEmptyMessageExcluded` is the only key
+carrying `{excluded}`.
 
 ### Settings Organization tab
 
@@ -418,6 +456,45 @@ the **noun for arranging files**, matching each locale's existing
 
 zh-CN/zh-TW use 整理 ("tidying/arranging"), not 组织/組織 (an organization as a group).
 
+### Sidecar storage feature (centralized `.metadata.json` / preview storage)
+
+The Library settings tab hosts an optional mode that stores `.metadata.json` sidecars and
+preview images either **alongside** each model file or in a single **centralized** mirror tree,
+plus the manual migration that moves existing files between the two. Everything lives in
+`settings.sections.sidecarStorage` (the section header inside the Library tab),
+`settings.sidecarStorage.*` and `modals.sidecarMigrationConfirm.*`.
+
+- **`sidecar` is a technical noun, not a brand**, so each locale either borrows it or uses its
+  own companion-file word — one rendering per file:
+
+| Term | Rendering |
+|---|---|
+| sidecar (noun) | zh-CN 附属文件 · zh-TW 附屬檔案 · ja サイドカーファイル · ko 사이드카 파일 · fr fichier sidecar · de Sidecar-Datei · es archivo sidecar · ru sidecar-файл · he קובץ לוואי |
+| centralized storage | zh-CN 集中存储 · zh-TW 集中儲存 · ja 集中保存 · ko 중앙 집중식 저장 · fr stockage centralisé · de zentrale Speicherung · es almacenamiento centralizado · ru централизованное хранилище · he אחסון מרכזי |
+| alongside model files | zh-CN 与模型文件放在一起 · zh-TW 與模型檔案放在一起 · ja モデルファイルの隣 · ko 모델 파일 옆 · fr à côté des fichiers de modèle · de neben den Modelldateien · es junto a los archivos de modelo · ru рядом с файлами моделей · he לצד קובצי המודלים |
+| migrate (verb/noun) | zh-CN 迁移 · zh-TW 遷移 · ja 移動 · ko 이동 · fr migrer / migration · de verschieben / Migration · es migrar / migración · ru перенести / перенос · he להעביר / העברה |
+| mirror (verb) | zh-CN 镜像 · zh-TW 對應 · ja ミラーリング · ko 미러링 · fr refléter · de spiegeln · es reflejar · ru повторять структуру · he לשקף |
+| preview images | zh-CN 预览图片 · zh-TW 預覽圖片 · ja プレビュー画像 · ko 미리보기 이미지 · fr images d’aperçu · de Vorschaubilder · es imágenes de vista previa · ru изображения превью · he תמונות תצוגה מקדימה |
+
+- `ja`/`ko` follow the file's existing storage-relocation verb (ja 移動, ko 이동, from
+  `settings.folderSettings.recipesPathMigrating`) rather than a transliteration of "migration";
+  `ru` uses перенос for the same reason, and `de` keeps the loan noun `Migration` while the verbs
+  use `verschieben`.
+- **`.metadata.json`**, **`.civitai.info`** and the default-path literal
+  `(<settings dir>/sidecars)` stay byte-identical in every locale — they are file names and a
+  path, not prose (§6 exception). Hebrew drops the wrapping parentheses to avoid bidi mirroring
+  and writes the literal bare.
+- `migrationDeferred` names a navigation path ("Settings → Library → Sidecar Storage"), so each
+  locale renders it with its **own** settings label and Library tab label
+  (`common.actions.settings` + `settings.nav.library` + the new section label), using the same
+  arrow and quoting style its other nav-path strings already use — zh-CN “设置 → 库 → …”,
+  zh-TW/ja 「設定 > … > …」, ko `설정 → …` bare, fr/de/es bare
+  (`Paramètres` / `Einstellungen` / `Configuración` → …), ru «Настройки → …»,
+  he `הגדרות > …` bare (cf. `other.noPaths.descriptionStandalone`).
+- The migrate-button label is quoted inside `confirmToCentralized` / `confirmToAlongside` with
+  each locale's UI-label quoting style (zh-CN “ ”, zh-TW/ja 「 」, ko `' '`, fr/ru/es/he « »,
+  de „ “), matching `settings.sidecarStorage.migrateButton` verbatim so the two never drift.
+
 ### Filename Templates feature
 
 Per-model-type templates that name downloaded model files; "Apply to Library Now"

docs/metadata-json-schema.md

@@ -11,6 +11,29 @@ This document defines the complete schema for `.metadata.json` files used by Lor
 
 ---
 
+## Storage Location (Alongside vs Centralized)
+
+By default, `.metadata.json` sidecars and preview images live **alongside** their model files. An optional centralized mode stores them under a single root directory instead. Two settings control this (Settings → Library → Sidecar Storage):
+
+| Setting | Values | Default |
+|---------|--------|---------|
+| `sidecar_storage_mode` | `"alongside"` \| `"centralized"` | `"alongside"` |
+| `sidecar_storage_path` | Absolute path string; empty = `<settings dir>/sidecars` | `""` |
+
+In centralized mode, sidecars and previews mirror the library-relative directory structure:
+
+```
+<sidecar_root>/<library>/<root_basename-roothash>/<rel_dir>/<name>.metadata.json
+```
+
+- `<library>` is the active library name and `<rel_dir>` the model's directory relative to the model root containing the file. `<root_basename-roothash>` combines the root's basename with a short hash of its full path so two roots sharing a basename (e.g. `/mnt/a/loras` and `/mnt/b/loras`) never collide. Each component is sanitized to filesystem-safe characters.
+- `.civitai.info` files always stay next to the model file, in both modes.
+- Changing the mode does **not** move existing files automatically — run the migration (`POST /api/lm/sidecars/migrate` with `{"direction": "to_centralized" | "to_alongside"}`, or the "Migrate Sidecars Now" button in settings).
+- Changing `sidecar_storage_path` while centralized likewise needs a root relocation: `{"direction": "relocate_root", "old_root": "<previous path>"}` moves the whole mirror tree to the new root (the settings UI offers this automatically).
+- All sidecar/preview path derivation goes through the helpers in `py/utils/sidecar_paths.py`; never construct paths inline.
+
+---
+
 ## Base Fields (All Model Types)
 
 These fields are present in all model metadata files.

locales/de.json

@@ -383,6 +383,7 @@
             "exampleImages": "Beispielbilder",
             "autoOrganize": "Auto-Organisierung",
             "metadata": "Metadaten",
+            "sidecarStorage": "Sidecar-Speicherung",
             "proxySettings": "Proxy-Einstellungen"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "Sidecar-Speichermodus",
+            "modeHelp": "Wählen Sie, wo .metadata.json-Sidecar-Dateien und Vorschaubilder gespeichert werden: neben jeder Modelldatei oder in einem einzelnen zentralen Verzeichnis, das Ihre Bibliotheksstruktur spiegelt. .civitai.info-Dateien bleiben immer neben der Modelldatei.",
+            "modeOptions": {
+                "alongside": "Neben den Modelldateien (Standard)",
+                "centralized": "Zentrale Speicherung"
+            },
+            "path": "Pfad der zentralen Speicherung",
+            "pathHelp": "Stammverzeichnis für die zentrale Sidecar-Speicherung. Leer lassen, um den Standardspeicherort (<settings dir>/sidecars) zu verwenden.",
+            "pathPlaceholder": "Leer = <settings dir>/sidecars",
+            "management": "Sidecar-Migration",
+            "managementHelp": "Verschieben Sie vorhandene .metadata.json-Sidecar-Dateien und Vorschaubilder zwischen der Ablage neben den Modelldateien und der zentralen Speicherung, passend zum aktuell gewählten Modus. Ein Moduswechsel verschiebt vorhandene Dateien nicht automatisch.",
+            "migrateButton": "Sidecar-Dateien jetzt verschieben",
+            "migratingButton": "Wird verschoben...",
+            "migrating": "Sidecar-Dateien werden verschoben...",
+            "migrateSuccess": "Sidecar-Migration erfolgreich abgeschlossen",
+            "migrateFailed": "Sidecar-Migration fehlgeschlagen: {message}",
+            "migrationDeferred": "Vorhandene Sidecar-Dateien wurden nicht verschoben. Sie können sie später unter Einstellungen → Bibliothek → Sidecar-Speicherung verschieben.",
+            "confirmToCentralized": "Der Speichermodus wurde geändert, aber vorhandene .metadata.json-Sidecar-Dateien und Vorschaubilder werden nicht automatisch verschoben. Jetzt in das zentrale Speicherverzeichnis verschieben? Sie können das auch später über die Schaltfläche „Sidecar-Dateien jetzt verschieben“ tun.",
+            "confirmToAlongside": "Der Speichermodus wurde geändert, aber vorhandene .metadata.json-Sidecar-Dateien und Vorschaubilder werden nicht automatisch verschoben. Jetzt wieder neben ihre Modelldateien verschieben? Sie können das auch später über die Schaltfläche „Sidecar-Dateien jetzt verschieben“ tun.",
+            "confirmRelocateRoot": "Das zentrale Speicherverzeichnis wurde geändert, aber vorhandene Sidecar-Dateien und Vorschaubilder liegen noch im vorherigen Verzeichnis. Jetzt in das neue Verzeichnis verschieben?"
+        },
         "proxySettings": {
             "enableProxy": "App-Proxy aktivieren",
             "enableProxyHelp": "Aktivieren Sie benutzerdefinierte Proxy-Einstellungen für diese Anwendung. Überschreibt die System-Proxy-Einstellungen.",
@@ -1350,6 +1373,10 @@
             "emptyNote": "Dieser Ordner enthält keine Modelle. Alle anderen darin enthaltenen Dateien werden ebenfalls gelöscht.",
             "notEmptyTitle": "Ordner ist nicht leer",
             "notEmptyMessage": "Dieser Ordner enthält noch Modelle. Löschen oder verschieben Sie diese zuerst — beim Löschen eines Ordners werden Modelldateien niemals mitgelöscht.",
+            "notEmptyMessageCount": "Dieser Ordner enthält noch {count} Modelldatei(en). Löschen oder verschieben Sie diese zuerst — beim Löschen eines Ordners werden Modelldateien niemals mitgelöscht.",
+            "notEmptyMessageExcluded": "Dieser Ordner enthält noch {count} Modelldatei(en), davon {excluded} von der Bibliothek ausgeschlossen. Heben Sie den Ausschluss unter „Ausgeschlossene Modelle verwalten“ auf und löschen Sie sie zuerst — beim Löschen eines Ordners werden Modelldateien niemals mitgelöscht.",
+            "busyTitle": "Eine Löschung steht noch aus",
+            "checking": "Ordnerinhalt wird geprüft...",
             "confirm": "Ordner löschen"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "Ordner wiederhergestellt",
             "failed": "Ordner konnte nicht gelöscht werden: {message}",
             "notEmpty": "Dieser Ordner enthält noch Modelle. Aktualisieren Sie die Seitenleiste und versuchen Sie es erneut.",
+            "notEmptyWithCount": "Dieser Ordner enthält noch {count} Modelldatei(en). Aktualisieren Sie die Seitenleiste und versuchen Sie es erneut.",
             "busy": "In diesem Ordner steht noch eine Löschung aus. Warten Sie, bis das Zeitfenster für das Rückgängigmachen abgelaufen ist.",
             "unsupported": "Das Löschen von Ordnern wird auf dieser Seite nicht unterstützt",
             "noRoot": "Es ist kein Modell-Stammverzeichnis konfiguriert"
@@ -1637,6 +1665,12 @@
             "titleRevert": "Ursprüngliche Dateinamen wiederherstellen?",
             "revertButton": "Ursprüngliche Dateinamen wiederherstellen"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "Sidecar-Dateien in die zentrale Speicherung verschieben?",
+            "titleToAlongside": "Sidecar-Dateien zurück neben die Modelldateien verschieben?",
+            "confirmButton": "Jetzt verschieben",
+            "titleRelocateRoot": "Sidecar-Dateien in das neue Speicherverzeichnis verschieben?"
+        },
         "bulkAddTags": {
             "title": "Tags zu mehreren Modellen hinzufügen",
             "description": "Tags hinzufügen zu",

locales/en.json

@@ -383,6 +383,7 @@
       "exampleImages": "Example Images",
       "autoOrganize": "Auto-organize",
       "metadata": "Metadata",
+      "sidecarStorage": "Sidecar Storage",
       "proxySettings": "Proxy Settings"
     },
     "nav": {
@@ -789,6 +790,28 @@
       "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
       "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
     },
+    "sidecarStorage": {
+      "mode": "Sidecar Storage Mode",
+      "modeHelp": "Choose where .metadata.json sidecars and preview images are stored: next to each model file, or in a single centralized directory that mirrors your library structure. .civitai.info files always stay next to the model file.",
+      "modeOptions": {
+        "alongside": "Alongside model files (default)",
+        "centralized": "Centralized storage"
+      },
+      "path": "Centralized Storage Path",
+      "pathHelp": "Root directory for centralized sidecar storage. Leave empty to use the default location (<settings dir>/sidecars).",
+      "pathPlaceholder": "Empty = <settings dir>/sidecars",
+      "management": "Sidecar Migration",
+      "managementHelp": "Move existing .metadata.json sidecars and preview images between alongside and centralized storage, matching the currently selected mode. Changing the mode does not move existing files automatically.",
+      "migrateButton": "Migrate Sidecars Now",
+      "migratingButton": "Migrating...",
+      "migrating": "Migrating sidecars...",
+      "migrateSuccess": "Sidecar migration completed successfully",
+      "migrateFailed": "Sidecar migration failed: {message}",
+      "migrationDeferred": "Existing sidecars were not moved. You can migrate them later from Settings → Library → Sidecar Storage.",
+      "confirmToCentralized": "The storage mode changed, but existing .metadata.json sidecars and preview images are not moved automatically. Move them into the centralized storage directory now? You can also do this later with the \"Migrate Sidecars Now\" button.",
+      "confirmToAlongside": "The storage mode changed, but existing .metadata.json sidecars and preview images are not moved automatically. Move them back next to their model files now? You can also do this later with the \"Migrate Sidecars Now\" button.",
+      "confirmRelocateRoot": "The centralized storage directory changed, but existing sidecars and preview images are still in the previous directory. Move them to the new directory now?"
+    },
     "proxySettings": {
       "enableProxy": "Enable App-level Proxy",
       "enableProxyHelp": "Enable custom proxy settings for this application, overriding system proxy settings",
@@ -1350,6 +1373,10 @@
       "emptyNote": "This folder contains no models. Any other files it holds will be deleted too.",
       "notEmptyTitle": "Folder is not empty",
       "notEmptyMessage": "This folder still contains models. Delete or move them first — deleting a folder never cascades over model files.",
+      "notEmptyMessageCount": "This folder still contains {count} model file(s). Delete or move them first — deleting a folder never cascades over model files.",
+      "notEmptyMessageExcluded": "This folder still contains {count} model file(s), {excluded} of them excluded from the library. Un-exclude them in Manage Excluded Models and delete them first — deleting a folder never cascades over model files.",
+      "busyTitle": "A deletion is still pending",
+      "checking": "Checking the folder contents...",
       "confirm": "Delete folder"
     },
     "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
       "restored": "Folder restored",
       "failed": "Failed to delete folder: {message}",
       "notEmpty": "This folder still contains models. Refresh the sidebar and try again.",
+      "notEmptyWithCount": "This folder still contains {count} model file(s). Refresh the sidebar and try again.",
       "busy": "A deletion is still pending inside this folder. Wait for the undo window to expire.",
       "unsupported": "Folder deletion is not supported on this page",
       "noRoot": "No model root is configured"
@@ -1637,6 +1665,12 @@
       "titleRevert": "Restore original filenames?",
       "revertButton": "Restore Original Filenames"
     },
+    "sidecarMigrationConfirm": {
+      "titleToCentralized": "Move sidecars to centralized storage?",
+      "titleToAlongside": "Move sidecars back next to model files?",
+      "confirmButton": "Migrate Now",
+      "titleRelocateRoot": "Move sidecars to the new storage directory?"
+    },
     "bulkAddTags": {
       "title": "Add Tags to Multiple Models",
       "description": "Add tags to",

locales/es.json

@@ -383,6 +383,7 @@
             "exampleImages": "Imágenes de ejemplo",
             "autoOrganize": "Organización automática",
             "metadata": "Metadatos",
+            "sidecarStorage": "Almacenamiento de archivos sidecar",
             "proxySettings": "Configuración de proxy"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "Modo de almacenamiento de archivos sidecar",
+            "modeHelp": "Elige dónde se guardan los archivos sidecar .metadata.json y las imágenes de vista previa: junto a cada archivo de modelo, o en un único directorio centralizado que refleja la estructura de tu biblioteca. Los archivos .civitai.info siempre permanecen junto al archivo de modelo.",
+            "modeOptions": {
+                "alongside": "Junto a los archivos de modelo (predeterminado)",
+                "centralized": "Almacenamiento centralizado"
+            },
+            "path": "Ruta del almacenamiento centralizado",
+            "pathHelp": "Carpeta raíz del almacenamiento centralizado de archivos sidecar. Déjalo vacío para usar la ubicación predeterminada (<settings dir>/sidecars).",
+            "pathPlaceholder": "Vacío = <settings dir>/sidecars",
+            "management": "Migración de archivos sidecar",
+            "managementHelp": "Mueve los archivos sidecar .metadata.json y las imágenes de vista previa existentes entre el almacenamiento junto a los modelos y el almacenamiento centralizado, según el modo seleccionado. Cambiar el modo no mueve los archivos existentes automáticamente.",
+            "migrateButton": "Migrar archivos sidecar ahora",
+            "migratingButton": "Migrando...",
+            "migrating": "Migrando archivos sidecar...",
+            "migrateSuccess": "Migración de archivos sidecar completada",
+            "migrateFailed": "Error al migrar los archivos sidecar: {message}",
+            "migrationDeferred": "Los archivos sidecar existentes no se movieron. Puedes migrarlos más tarde desde Configuración → Biblioteca → Almacenamiento de archivos sidecar.",
+            "confirmToCentralized": "El modo de almacenamiento ha cambiado, pero los archivos sidecar .metadata.json y las imágenes de vista previa existentes no se mueven automáticamente. ¿Moverlos ahora al directorio de almacenamiento centralizado? También puedes hacerlo más tarde con el botón «Migrar archivos sidecar ahora».",
+            "confirmToAlongside": "El modo de almacenamiento ha cambiado, pero los archivos sidecar .metadata.json y las imágenes de vista previa existentes no se mueven automáticamente. ¿Devolverlos ahora junto a sus archivos de modelo? También puedes hacerlo más tarde con el botón «Migrar archivos sidecar ahora».",
+            "confirmRelocateRoot": "El directorio de almacenamiento centralizado ha cambiado, pero los archivos sidecar y las imágenes de vista previa existentes siguen en el directorio anterior. ¿Moverlos ahora al nuevo directorio?"
+        },
         "proxySettings": {
             "enableProxy": "Habilitar proxy a nivel de aplicación",
             "enableProxyHelp": "Habilita la configuración de proxy personalizada para esta aplicación, sobrescribiendo la configuración de proxy del sistema",
@@ -1350,6 +1373,10 @@
             "emptyNote": "Esta carpeta no contiene modelos. Los demás archivos que contenga también se eliminarán.",
             "notEmptyTitle": "La carpeta no está vacía",
             "notEmptyMessage": "Esta carpeta aún contiene modelos. Elimínalos o muévelos primero — eliminar una carpeta nunca elimina los archivos de modelo en cascada.",
+            "notEmptyMessageCount": "Esta carpeta aún contiene {count} archivo(s) de modelo. Elimínalos o muévelos primero — eliminar una carpeta nunca elimina los archivos de modelo en cascada.",
+            "notEmptyMessageExcluded": "Esta carpeta aún contiene {count} archivo(s) de modelo, de los cuales {excluded} están excluidos de la biblioteca. Anula su exclusión en «Gestionar modelos excluidos» y elimínalos primero — eliminar una carpeta nunca elimina los archivos de modelo en cascada.",
+            "busyTitle": "Todavía hay una eliminación pendiente",
+            "checking": "Comprobando el contenido de la carpeta...",
             "confirm": "Eliminar carpeta"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "Carpeta restaurada",
             "failed": "Error al eliminar la carpeta: {message}",
             "notEmpty": "Esta carpeta aún contiene modelos. Actualiza la barra lateral e inténtalo de nuevo.",
+            "notEmptyWithCount": "Esta carpeta aún contiene {count} archivo(s) de modelo. Actualiza la barra lateral e inténtalo de nuevo.",
             "busy": "Todavía hay una eliminación pendiente dentro de esta carpeta. Espera a que caduque la ventana de deshacer.",
             "unsupported": "La eliminación de carpetas no es compatible con esta página",
             "noRoot": "No hay ninguna raíz de modelo configurada"
@@ -1637,6 +1665,12 @@
             "titleRevert": "¿Restaurar los nombres de archivo originales?",
             "revertButton": "Restaurar nombres de archivo originales"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "¿Mover los archivos sidecar al almacenamiento centralizado?",
+            "titleToAlongside": "¿Devolver los archivos sidecar junto a los archivos de modelo?",
+            "confirmButton": "Migrar ahora",
+            "titleRelocateRoot": "¿Mover los archivos sidecar al nuevo directorio de almacenamiento?"
+        },
         "bulkAddTags": {
             "title": "Añadir etiquetas a múltiples modelos",
             "description": "Añadir etiquetas a",

locales/fr.json

@@ -383,6 +383,7 @@
             "exampleImages": "Images d'exemple",
             "autoOrganize": "Organisation automatique",
             "metadata": "Métadonnées",
+            "sidecarStorage": "Stockage des fichiers sidecar",
             "proxySettings": "Paramètres du proxy"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "Mode de stockage des fichiers sidecar",
+            "modeHelp": "Choisissez où sont stockés les fichiers sidecar .metadata.json et les images d’aperçu : à côté de chaque fichier de modèle, ou dans un seul dossier centralisé qui reflète la structure de votre bibliothèque. Les fichiers .civitai.info restent toujours à côté du fichier de modèle.",
+            "modeOptions": {
+                "alongside": "À côté des fichiers de modèle (par défaut)",
+                "centralized": "Stockage centralisé"
+            },
+            "path": "Chemin du stockage centralisé",
+            "pathHelp": "Dossier racine du stockage centralisé des fichiers sidecar. Laissez vide pour utiliser l’emplacement par défaut (<settings dir>/sidecars).",
+            "pathPlaceholder": "Vide = <settings dir>/sidecars",
+            "management": "Migration des fichiers sidecar",
+            "managementHelp": "Déplacez les fichiers sidecar .metadata.json et les images d’aperçu existants entre le stockage à côté des modèles et le stockage centralisé, selon le mode sélectionné. Changer de mode ne déplace pas les fichiers existants automatiquement.",
+            "migrateButton": "Migrer les fichiers sidecar maintenant",
+            "migratingButton": "Migration en cours...",
+            "migrating": "Migration des fichiers sidecar en cours...",
+            "migrateSuccess": "Migration des fichiers sidecar terminée",
+            "migrateFailed": "Échec de la migration des fichiers sidecar : {message}",
+            "migrationDeferred": "Les fichiers sidecar existants n’ont pas été déplacés. Vous pouvez les migrer plus tard depuis Paramètres → Bibliothèque → Stockage des fichiers sidecar.",
+            "confirmToCentralized": "Le mode de stockage a changé, mais les fichiers sidecar .metadata.json et les images d’aperçu existants ne sont pas déplacés automatiquement. Les déplacer maintenant dans le dossier de stockage centralisé ? Vous pouvez aussi le faire plus tard avec le bouton « Migrer les fichiers sidecar maintenant ».",
+            "confirmToAlongside": "Le mode de stockage a changé, mais les fichiers sidecar .metadata.json et les images d’aperçu existants ne sont pas déplacés automatiquement. Les remettre maintenant à côté de leurs fichiers de modèle ? Vous pouvez aussi le faire plus tard avec le bouton « Migrer les fichiers sidecar maintenant ».",
+            "confirmRelocateRoot": "Le dossier de stockage centralisé a changé, mais les fichiers sidecar et les images d’aperçu existants se trouvent encore dans le dossier précédent. Les déplacer maintenant dans le nouveau dossier ?"
+        },
         "proxySettings": {
             "enableProxy": "Activer le proxy au niveau de l'application",
             "enableProxyHelp": "Activer les paramètres de proxy personnalisés pour cette application, remplaçant les paramètres de proxy système",
@@ -1350,6 +1373,10 @@
             "emptyNote": "Ce dossier ne contient aucun modèle. Les autres fichiers qu’il contient seront également supprimés.",
             "notEmptyTitle": "Le dossier n’est pas vide",
             "notEmptyMessage": "Ce dossier contient encore des modèles. Supprimez-les ou déplacez-les d’abord — la suppression d’un dossier n’entraîne jamais celle des fichiers de modèles.",
+            "notEmptyMessageCount": "Ce dossier contient encore {count} fichier(s) de modèle. Supprimez-les ou déplacez-les d’abord — la suppression d’un dossier n’entraîne jamais celle des fichiers de modèles.",
+            "notEmptyMessageExcluded": "Ce dossier contient encore {count} fichier(s) de modèle, dont {excluded} sont exclus de la bibliothèque. Annulez leur exclusion dans « Gérer les modèles exclus » et supprimez-les d’abord — la suppression d’un dossier n’entraîne jamais celle des fichiers de modèles.",
+            "busyTitle": "Une suppression est encore en attente",
+            "checking": "Vérification du contenu du dossier...",
             "confirm": "Supprimer le dossier"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "Dossier restauré",
             "failed": "Échec de la suppression du dossier : {message}",
             "notEmpty": "Ce dossier contient encore des modèles. Actualisez la barre latérale et réessayez.",
+            "notEmptyWithCount": "Ce dossier contient encore {count} fichier(s) de modèle. Actualisez la barre latérale et réessayez.",
             "busy": "Une suppression est encore en attente dans ce dossier. Attendez la fin de la fenêtre d’annulation.",
             "unsupported": "La suppression de dossiers n’est pas prise en charge sur cette page",
             "noRoot": "Aucune racine de modèle n’est configurée"
@@ -1637,6 +1665,12 @@
             "titleRevert": "Restaurer les noms de fichier d'origine ?",
             "revertButton": "Restaurer les noms de fichier d'origine"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "Déplacer les fichiers sidecar vers le stockage centralisé ?",
+            "titleToAlongside": "Remettre les fichiers sidecar à côté des fichiers de modèle ?",
+            "confirmButton": "Migrer maintenant",
+            "titleRelocateRoot": "Déplacer les fichiers sidecar vers le nouveau dossier de stockage ?"
+        },
         "bulkAddTags": {
             "title": "Ajouter des tags à plusieurs modèles",
             "description": "Ajouter des tags à",

locales/he.json

@@ -383,6 +383,7 @@
             "exampleImages": "תמונות דוגמה",
             "autoOrganize": "ארגון אוטומטי",
             "metadata": "מטא-נתונים",
+            "sidecarStorage": "אחסון קובצי לוואי",
             "proxySettings": "הגדרות פרוקסי"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "מצב אחסון קובצי לוואי",
+            "modeHelp": "בחר היכן יאוחסנו קובצי הלוואי .metadata.json ותמונות התצוגה המקדימה: לצד כל קובץ מודל, או בתיקייה מרכזית אחת שמשקפת את מבנה הספרייה שלך. קובצי .civitai.info נשארים תמיד לצד קובץ המודל.",
+            "modeOptions": {
+                "alongside": "לצד קובצי המודלים (ברירת מחדל)",
+                "centralized": "אחסון מרכזי"
+            },
+            "path": "נתיב האחסון המרכזי",
+            "pathHelp": "תיקיית השורש של אחסון קובצי הלוואי המרכזי. השאר ריק כדי להשתמש במיקום ברירת המחדל <settings dir>/sidecars.",
+            "pathPlaceholder": "ריק = <settings dir>/sidecars",
+            "management": "העברת קובצי לוואי",
+            "managementHelp": "העבר קובצי לוואי .metadata.json ותמונות תצוגה מקדימה קיימים בין אחסון לצד המודלים לאחסון המרכזי, בהתאם למצב שנבחר. שינוי המצב אינו מעביר קבצים קיימים באופן אוטומטי.",
+            "migrateButton": "העבר קובצי לוואי כעת",
+            "migratingButton": "מעביר...",
+            "migrating": "מעביר קובצי לוואי...",
+            "migrateSuccess": "העברת קובצי הלוואי הושלמה בהצלחה",
+            "migrateFailed": "העברת קובצי הלוואי נכשלה: {message}",
+            "migrationDeferred": "קובצי הלוואי הקיימים לא הועברו. ניתן להעביר אותם מאוחר יותר דרך הגדרות > ספרייה > אחסון קובצי לוואי.",
+            "confirmToCentralized": "מצב האחסון השתנה, אך קובצי הלוואי .metadata.json ותמונות התצוגה המקדימה הקיימים אינם מועברים אוטומטית. להעביר אותם כעת לתיקיית האחסון המרכזי? ניתן לעשות זאת גם מאוחר יותר באמצעות הכפתור «העבר קובצי לוואי כעת».",
+            "confirmToAlongside": "מצב האחסון השתנה, אך קובצי הלוואי .metadata.json ותמונות התצוגה המקדימה הקיימים אינם מועברים אוטומטית. להחזיר אותם כעת לצד קובצי המודל שלהם? ניתן לעשות זאת גם מאוחר יותר באמצעות הכפתור «העבר קובצי לוואי כעת».",
+            "confirmRelocateRoot": "תיקיית האחסון המרכזי השתנתה, אך קובצי הלוואי ותמונות התצוגה המקדימה הקיימים עדיין נמצאים בתיקייה הקודמת. להעביר אותם כעת לתיקייה החדשה?"
+        },
         "proxySettings": {
             "enableProxy": "הפעל פרוקסי ברמת האפליקציה",
             "enableProxyHelp": "אפשר הגדרות פרוקסי מותאמות אישית עבור יישום זה, במקום הגדרות הפרוקסי של המערכת",
@@ -1350,6 +1373,10 @@
             "emptyNote": "אין מודלים בתיקייה זו. קבצים אחרים שבה יימחקו גם הם.",
             "notEmptyTitle": "התיקייה אינה ריקה",
             "notEmptyMessage": "בתיקייה זו עדיין יש מודלים. מחק או העבר אותם תחילה — מחיקת תיקייה לעולם אינה מוחקת קובצי מודלים.",
+            "notEmptyMessageCount": "בתיקייה זו עדיין יש {count} קובצי מודלים. מחק או העבר אותם תחילה — מחיקת תיקייה לעולם אינה מוחקת קובצי מודלים.",
+            "notEmptyMessageExcluded": "בתיקייה זו עדיין יש {count} קובצי מודלים, שמהם {excluded} מוחרגים מהספרייה. בטל את ההחרגה ב«ניהול מודלים מוחרגים» ומחק אותם תחילה — מחיקת תיקייה לעולם אינה מוחקת קובצי מודלים.",
+            "busyTitle": "מחיקה עדיין ממתינה",
+            "checking": "בודק את תוכן התיקייה...",
             "confirm": "מחק תיקייה"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "התיקייה שוחזרה",
             "failed": "מחיקת התיקייה נכשלה: {message}",
             "notEmpty": "בתיקייה זו עדיין יש מודלים. רענן את סרגל הצד ונסה שוב.",
+            "notEmptyWithCount": "בתיקייה זו עדיין יש {count} קובצי מודלים. רענן את סרגל הצד ונסה שוב.",
             "busy": "מחיקה עדיין ממתינה בתיקייה זו. המתן לסיום חלון הביטול.",
             "unsupported": "מחיקת תיקיות אינה נתמכת בדף זה",
             "noRoot": "לא הוגדר שורש מודלים"
@@ -1637,6 +1665,12 @@
             "titleRevert": "לשחזר שמות קבצים מקוריים?",
             "revertButton": "שחזר שמות קבצים מקוריים"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "להעביר את קובצי הלוואי לאחסון המרכזי?",
+            "titleToAlongside": "להחזיר את קובצי הלוואי לצד קובצי המודל?",
+            "confirmButton": "העבר כעת",
+            "titleRelocateRoot": "להעביר את קובצי הלוואי לתיקיית האחסון החדשה?"
+        },
         "bulkAddTags": {
             "title": "הוסף תגיות למספר מודלים",
             "description": "הוסף תגיות ל-",

locales/ja.json

@@ -383,6 +383,7 @@
             "exampleImages": "例画像",
             "autoOrganize": "自動整理",
             "metadata": "メタデータ",
+            "sidecarStorage": "サイドカーファイルの保存",
             "proxySettings": "プロキシ設定"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "サイドカーファイルの保存モード",
+            "modeHelp": ".metadata.json サイドカーファイルとプレビュー画像の保存先を選択します。各モデルファイルの隣に保存するか、ライブラリ構造をミラーリングした単一の集中ディレクトリに保存します。.civitai.info ファイルは常にモデルファイルの隣に置かれます。",
+            "modeOptions": {
+                "alongside": "モデルファイルの隣（デフォルト）",
+                "centralized": "集中保存"
+            },
+            "path": "集中保存先パス",
+            "pathHelp": "サイドカーファイルを集中保存するルートディレクトリ。空欄の場合は既定の場所（<settings dir>/sidecars）を使用します。",
+            "pathPlaceholder": "空欄 = <settings dir>/sidecars",
+            "management": "サイドカーファイルの移動",
+            "managementHelp": "既存の .metadata.json サイドカーファイルとプレビュー画像を、現在選択されているモードに合わせて「モデルファイルの隣」と「集中保存」の間で移動します。モードを変更しても既存ファイルは自動では移動しません。",
+            "migrateButton": "今すぐサイドカーファイルを移動",
+            "migratingButton": "移動しています...",
+            "migrating": "サイドカーファイルを移動しています...",
+            "migrateSuccess": "サイドカーファイルの移動が完了しました",
+            "migrateFailed": "サイドカーファイルの移動に失敗しました：{message}",
+            "migrationDeferred": "既存のサイドカーファイルは移動されませんでした。後で「設定 > ライブラリ > サイドカーファイルの保存」から移動できます。",
+            "confirmToCentralized": "保存モードが変更されましたが、既存の .metadata.json サイドカーファイルとプレビュー画像は自動では移動しません。今すぐ集中保存ディレクトリに移動しますか？「今すぐサイドカーファイルを移動」ボタンで後から実行することもできます。",
+            "confirmToAlongside": "保存モードが変更されましたが、既存の .metadata.json サイドカーファイルとプレビュー画像は自動では移動しません。今すぐ各モデルファイルの隣に戻しますか？「今すぐサイドカーファイルを移動」ボタンで後から実行することもできます。",
+            "confirmRelocateRoot": "集中保存ディレクトリが変更されましたが、既存のサイドカーファイルとプレビュー画像はまだ以前のディレクトリにあります。今すぐ新しいディレクトリに移動しますか？"
+        },
         "proxySettings": {
             "enableProxy": "アプリレベルのプロキシを有効化",
             "enableProxyHelp": "このアプリケーション専用のカスタムプロキシ設定を有効にします（システムのプロキシ設定を上書きします）",
@@ -1350,6 +1373,10 @@
             "emptyNote": "このフォルダにはモデルがありません。他のファイルもすべて削除されます。",
             "notEmptyTitle": "フォルダが空ではありません",
             "notEmptyMessage": "このフォルダにはまだモデルがあります。先に削除するか移動してください —— フォルダを削除してもモデルファイルがまとめて削除されることはありません。",
+            "notEmptyMessageCount": "このフォルダにはまだ {count} 個のモデルファイルがあります。先に削除するか移動してください —— フォルダを削除してもモデルファイルがまとめて削除されることはありません。",
+            "notEmptyMessageExcluded": "このフォルダにはまだ {count} 個のモデルファイルがあり、そのうち {excluded} 個はライブラリから除外されています。「除外モデルを管理」で除外を解除してから削除してください —— フォルダを削除してもモデルファイルがまとめて削除されることはありません。",
+            "busyTitle": "保留中の削除があります",
+            "checking": "フォルダの内容を確認しています...",
             "confirm": "フォルダを削除"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "フォルダを復元しました",
             "failed": "フォルダの削除に失敗しました: {message}",
             "notEmpty": "このフォルダにはまだモデルがあります。サイドバーを再読み込みしてからもう一度お試しください。",
+            "notEmptyWithCount": "このフォルダにはまだ {count} 個のモデルファイルがあります。サイドバーを再読み込みしてからもう一度お試しください。",
             "busy": "このフォルダ内に保留中の削除があります。取り消し可能な時間が過ぎるまでお待ちください。",
             "unsupported": "このページではフォルダを削除できません",
             "noRoot": "モデルルートが設定されていません"
@@ -1637,6 +1665,12 @@
             "titleRevert": "元のファイル名を復元しますか？",
             "revertButton": "元のファイル名を復元"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "サイドカーファイルを集中保存に移動しますか？",
+            "titleToAlongside": "サイドカーファイルをモデルファイルの隣に戻しますか？",
+            "confirmButton": "今すぐ移動",
+            "titleRelocateRoot": "サイドカーファイルを新しい保存ディレクトリに移動しますか？"
+        },
         "bulkAddTags": {
             "title": "複数モデルにタグを追加",
             "description": "タグを追加するモデル：",

locales/ko.json

@@ -383,6 +383,7 @@
             "exampleImages": "예시 이미지",
             "autoOrganize": "자동 정리",
             "metadata": "메타데이터",
+            "sidecarStorage": "사이드카 파일 저장",
             "proxySettings": "프록시 설정"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "사이드카 파일 저장 모드",
+            "modeHelp": ".metadata.json 사이드카 파일과 미리보기 이미지를 저장할 위치를 선택하세요. 각 모델 파일 옆에 저장하거나, 라이브러리 구조를 미러링하는 단일 중앙 집중식 디렉터리에 저장할 수 있습니다. .civitai.info 파일은 항상 모델 파일 옆에 남습니다.",
+            "modeOptions": {
+                "alongside": "모델 파일 옆 (기본값)",
+                "centralized": "중앙 집중식 저장"
+            },
+            "path": "중앙 집중식 저장 경로",
+            "pathHelp": "사이드카 파일을 중앙 집중식으로 저장할 루트 디렉터리입니다. 비워 두면 기본 위치(<settings dir>/sidecars)를 사용합니다.",
+            "pathPlaceholder": "비움 = <settings dir>/sidecars",
+            "management": "사이드카 파일 이동",
+            "managementHelp": "기존 .metadata.json 사이드카 파일과 미리보기 이미지를 현재 선택한 모드에 맞게 '모델 파일 옆'과 '중앙 집중식 저장' 사이에서 이동합니다. 모드를 변경해도 기존 파일은 자동으로 이동되지 않습니다.",
+            "migrateButton": "지금 사이드카 파일 이동",
+            "migratingButton": "이동 중...",
+            "migrating": "사이드카 파일을 이동하는 중...",
+            "migrateSuccess": "사이드카 파일 이동이 완료되었습니다",
+            "migrateFailed": "사이드카 파일 이동 실패: {message}",
+            "migrationDeferred": "기존 사이드카 파일은 이동되지 않았습니다. 나중에 설정 → 라이브러리 → 사이드카 파일 저장에서 이동할 수 있습니다.",
+            "confirmToCentralized": "저장 모드가 변경되었지만 기존 .metadata.json 사이드카 파일과 미리보기 이미지는 자동으로 이동되지 않습니다. 지금 중앙 집중식 저장 디렉터리로 이동할까요? '지금 사이드카 파일 이동' 버튼으로 나중에 실행할 수도 있습니다.",
+            "confirmToAlongside": "저장 모드가 변경되었지만 기존 .metadata.json 사이드카 파일과 미리보기 이미지는 자동으로 이동되지 않습니다. 지금 각 모델 파일 옆으로 되돌릴까요? '지금 사이드카 파일 이동' 버튼으로 나중에 실행할 수도 있습니다.",
+            "confirmRelocateRoot": "중앙 집중식 저장 디렉터리가 변경되었지만 기존 사이드카 파일과 미리보기 이미지는 아직 이전 디렉터리에 있습니다. 지금 새 디렉터리로 이동할까요?"
+        },
         "proxySettings": {
             "enableProxy": "앱 수준 프록시 활성화",
             "enableProxyHelp": "이 애플리케이션에 대한 사용자 지정 프록시 설정을 활성화하여 시스템 프록시 설정을 무시합니다",
@@ -1350,6 +1373,10 @@
             "emptyNote": "이 폴더에는 모델이 없습니다. 폴더 안의 다른 파일도 함께 삭제됩니다.",
             "notEmptyTitle": "폴더가 비어 있지 않습니다",
             "notEmptyMessage": "이 폴더에는 아직 모델이 있습니다. 먼저 해당 모델을 삭제하거나 이동하세요 —— 폴더를 삭제해도 모델 파일이 함께 삭제되지는 않습니다.",
+            "notEmptyMessageCount": "이 폴더에는 아직 모델 파일이 {count}개 있습니다. 먼저 해당 모델을 삭제하거나 이동하세요 —— 폴더를 삭제해도 모델 파일이 함께 삭제되지는 않습니다.",
+            "notEmptyMessageExcluded": "이 폴더에는 아직 모델 파일이 {count}개 있으며, 그중 {excluded}개는 라이브러리에서 제외되어 있습니다. '제외된 모델 관리'에서 제외를 해제한 뒤 먼저 삭제하세요 —— 폴더를 삭제해도 모델 파일이 함께 삭제되지는 않습니다.",
+            "busyTitle": "대기 중인 삭제 작업이 있습니다",
+            "checking": "폴더 내용을 확인하는 중...",
             "confirm": "폴더 삭제"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "폴더를 복원했습니다",
             "failed": "폴더 삭제 실패: {message}",
             "notEmpty": "이 폴더에는 아직 모델이 있습니다. 사이드바를 새로 고친 후 다시 시도하세요.",
+            "notEmptyWithCount": "이 폴더에는 아직 모델 파일이 {count}개 있습니다. 사이드바를 새로 고친 후 다시 시도하세요.",
             "busy": "이 폴더에 아직 대기 중인 삭제 작업이 있습니다. 되돌리기 시간이 끝날 때까지 기다리세요.",
             "unsupported": "이 페이지에서는 폴더를 삭제할 수 없습니다",
             "noRoot": "모델 루트가 설정되지 않았습니다"
@@ -1637,6 +1665,12 @@
             "titleRevert": "원본 파일명을 복원하시겠습니까?",
             "revertButton": "원본 파일명 복원"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "사이드카 파일을 중앙 집중식 저장으로 이동할까요?",
+            "titleToAlongside": "사이드카 파일을 모델 파일 옆으로 되돌릴까요?",
+            "confirmButton": "지금 이동",
+            "titleRelocateRoot": "사이드카 파일을 새 저장 디렉터리로 이동할까요?"
+        },
         "bulkAddTags": {
             "title": "여러 모델에 태그 추가",
             "description": "다음에 태그를 추가합니다:",

locales/ru.json

@@ -383,6 +383,7 @@
             "exampleImages": "Примеры изображений",
             "autoOrganize": "Автоорганизация",
             "metadata": "Метаданные",
+            "sidecarStorage": "Хранилище sidecar-файлов",
             "proxySettings": "Настройки прокси"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "Режим хранения sidecar-файлов",
+            "modeHelp": "Выберите, где хранить sidecar-файлы .metadata.json и изображения превью: рядом с каждым файлом модели или в одном централизованном каталоге, повторяющем структуру вашей библиотеки. Файлы .civitai.info всегда остаются рядом с файлом модели.",
+            "modeOptions": {
+                "alongside": "Рядом с файлами моделей (по умолчанию)",
+                "centralized": "Централизованное хранилище"
+            },
+            "path": "Путь централизованного хранилища",
+            "pathHelp": "Корневой каталог централизованного хранилища sidecar-файлов. Оставьте пустым, чтобы использовать расположение по умолчанию (<settings dir>/sidecars).",
+            "pathPlaceholder": "Пусто = <settings dir>/sidecars",
+            "management": "Перенос sidecar-файлов",
+            "managementHelp": "Переносите существующие sidecar-файлы .metadata.json и изображения превью между хранением рядом с моделями и централизованным хранилищем в соответствии с выбранным режимом. Смена режима не переносит существующие файлы автоматически.",
+            "migrateButton": "Перенести sidecar-файлы сейчас",
+            "migratingButton": "Перенос...",
+            "migrating": "Перенос sidecar-файлов...",
+            "migrateSuccess": "Перенос sidecar-файлов успешно завершён",
+            "migrateFailed": "Не удалось перенести sidecar-файлы: {message}",
+            "migrationDeferred": "Существующие sidecar-файлы не были перенесены. Вы можете перенести их позже в разделе «Настройки → Библиотека → Хранилище sidecar-файлов».",
+            "confirmToCentralized": "Режим хранения изменён, но существующие sidecar-файлы .metadata.json и изображения превью не переносятся автоматически. Перенести их сейчас в централизованное хранилище? Это также можно сделать позже кнопкой «Перенести sidecar-файлы сейчас».",
+            "confirmToAlongside": "Режим хранения изменён, но существующие sidecar-файлы .metadata.json и изображения превью не переносятся автоматически. Вернуть их сейчас рядом с их файлами моделей? Это также можно сделать позже кнопкой «Перенести sidecar-файлы сейчас».",
+            "confirmRelocateRoot": "Каталог централизованного хранилища изменён, но существующие sidecar-файлы и изображения превью всё ещё находятся в прежнем каталоге. Перенести их сейчас в новый каталог?"
+        },
         "proxySettings": {
             "enableProxy": "Включить прокси на уровне приложения",
             "enableProxyHelp": "Включить пользовательские настройки прокси для этого приложения, переопределяя системные настройки прокси",
@@ -1350,6 +1373,10 @@
             "emptyNote": "В этой папке нет моделей. Остальные файлы в ней тоже будут удалены.",
             "notEmptyTitle": "Папка не пуста",
             "notEmptyMessage": "В этой папке ещё есть модели. Сначала удалите или переместите их — удаление папки никогда не затрагивает файлы моделей.",
+            "notEmptyMessageCount": "В этой папке ещё есть {count} файл(ов) модели. Сначала удалите или переместите их — удаление папки никогда не затрагивает файлы моделей.",
+            "notEmptyMessageExcluded": "В этой папке ещё есть {count} файл(ов) модели, из них {excluded} исключены из библиотеки. Снимите исключение в разделе «Управление исключёнными моделями» и удалите их — удаление папки никогда не затрагивает файлы моделей.",
+            "busyTitle": "Удаление всё ещё отложено",
+            "checking": "Проверка содержимого папки...",
             "confirm": "Удалить папку"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "Папка восстановлена",
             "failed": "Не удалось удалить папку: {message}",
             "notEmpty": "В этой папке ещё есть модели. Обновите боковую панель и повторите попытку.",
+            "notEmptyWithCount": "В этой папке ещё есть {count} файл(ов) модели. Обновите боковую панель и повторите попытку.",
             "busy": "В этой папке всё ещё есть отложенное удаление. Дождитесь окончания окна отмены.",
             "unsupported": "Удаление папок не поддерживается на этой странице",
             "noRoot": "Корневая папка моделей не настроена"
@@ -1637,6 +1665,12 @@
             "titleRevert": "Восстановить исходные имена файлов?",
             "revertButton": "Восстановить исходные имена файлов"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "Перенести sidecar-файлы в централизованное хранилище?",
+            "titleToAlongside": "Вернуть sidecar-файлы рядом с файлами моделей?",
+            "confirmButton": "Перенести сейчас",
+            "titleRelocateRoot": "Перенести sidecar-файлы в новый каталог хранилища?"
+        },
         "bulkAddTags": {
             "title": "Добавить теги к нескольким моделям",
             "description": "Добавить теги к",

locales/zh-CN.json

@@ -383,6 +383,7 @@
             "exampleImages": "示例图片",
             "autoOrganize": "自动整理",
             "metadata": "元数据",
+            "sidecarStorage": "附属文件存储",
             "proxySettings": "代理设置"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "附属文件存储模式",
+            "modeHelp": "选择 .metadata.json 附属文件和预览图片的存放位置：与每个模型文件放在一起，或集中存放在一个镜像模型库结构的目录中。.civitai.info 文件始终与模型文件放在一起。",
+            "modeOptions": {
+                "alongside": "与模型文件放在一起（默认）",
+                "centralized": "集中存储"
+            },
+            "path": "集中存储路径",
+            "pathHelp": "集中存储附属文件的根目录。留空则使用默认位置（<settings dir>/sidecars）。",
+            "pathPlaceholder": "留空 = <settings dir>/sidecars",
+            "management": "附属文件迁移",
+            "managementHelp": "在“与模型文件放在一起”和“集中存储”之间迁移现有的 .metadata.json 附属文件和预览图片，以匹配当前选择的模式。更改模式不会自动迁移现有文件。",
+            "migrateButton": "立即迁移附属文件",
+            "migratingButton": "迁移中...",
+            "migrating": "正在迁移附属文件...",
+            "migrateSuccess": "附属文件迁移完成",
+            "migrateFailed": "附属文件迁移失败：{message}",
+            "migrationDeferred": "现有附属文件未迁移。你可以稍后在“设置 → 库 → 附属文件存储”中迁移它们。",
+            "confirmToCentralized": "存储模式已更改，但现有的 .metadata.json 附属文件和预览图片不会自动迁移。要现在将它们移入集中存储目录吗？你也可以稍后使用“立即迁移附属文件”按钮完成。",
+            "confirmToAlongside": "存储模式已更改，但现有的 .metadata.json 附属文件和预览图片不会自动迁移。要现在将它们移回各自的模型文件旁边吗？你也可以稍后使用“立即迁移附属文件”按钮完成。",
+            "confirmRelocateRoot": "集中存储目录已更改，但现有的附属文件和预览图片仍在原目录中。要现在将它们移到新目录吗？"
+        },
         "proxySettings": {
             "enableProxy": "启用应用级代理",
             "enableProxyHelp": "为此应用启用自定义代理设置，覆盖系统代理设置",
@@ -1350,6 +1373,10 @@
             "emptyNote": "该文件夹中没有模型，其中的其他文件也会一并删除。",
             "notEmptyTitle": "文件夹不为空",
             "notEmptyMessage": "该文件夹中仍有模型，请先删除或移出这些模型 —— 删除文件夹不会级联删除模型文件。",
+            "notEmptyMessageCount": "该文件夹中仍有 {count} 个模型文件，请先删除或移出这些模型 —— 删除文件夹不会级联删除模型文件。",
+            "notEmptyMessageExcluded": "该文件夹中仍有 {count} 个模型文件，其中 {excluded} 个已从模型库中排除。请先在“管理已排除的模型”中取消排除并删除它们 —— 删除文件夹不会级联删除模型文件。",
+            "busyTitle": "仍有删除操作待处理",
+            "checking": "正在检查文件夹内容...",
             "confirm": "删除文件夹"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "文件夹已恢复",
             "failed": "删除文件夹失败: {message}",
             "notEmpty": "该文件夹中仍有模型。请刷新侧边栏后重试。",
+            "notEmptyWithCount": "该文件夹中仍有 {count} 个模型文件。请刷新侧边栏后重试。",
             "busy": "该文件夹内仍有待处理的删除操作，请等待撤销窗口结束。",
             "unsupported": "此页面不支持删除文件夹",
             "noRoot": "未配置模型根目录"
@@ -1637,6 +1665,12 @@
             "titleRevert": "恢复原始文件名？",
             "revertButton": "恢复原始文件名"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "要将附属文件移到集中存储吗？",
+            "titleToAlongside": "要将附属文件移回模型文件旁边吗？",
+            "confirmButton": "立即迁移",
+            "titleRelocateRoot": "要将附属文件移到新的存储目录吗？"
+        },
         "bulkAddTags": {
             "title": "批量添加标签",
             "description": "为多个模型添加标签",

locales/zh-TW.json

@@ -383,6 +383,7 @@
             "exampleImages": "範例圖片",
             "autoOrganize": "自動整理",
             "metadata": "中繼資料",
+            "sidecarStorage": "附屬檔案儲存",
             "proxySettings": "代理設定"
         },
         "nav": {
@@ -789,6 +790,28 @@
             "providerOrderCivitaiArchiveSqlite": "CivitAI → CivArchive → Archive DB",
             "providerOrderCivitaiSqliteArchive": "CivitAI → Archive DB → CivArchive"
         },
+        "sidecarStorage": {
+            "mode": "附屬檔案儲存模式",
+            "modeHelp": "選擇 .metadata.json 附屬檔案與預覽圖片的存放位置：與每個模型檔案放在一起，或集中在一個對應模型庫結構的目錄中。.civitai.info 檔案一律與模型檔案放在一起。",
+            "modeOptions": {
+                "alongside": "與模型檔案放在一起（預設）",
+                "centralized": "集中儲存"
+            },
+            "path": "集中儲存路徑",
+            "pathHelp": "集中儲存附屬檔案的根目錄。留空則使用預設位置（<settings dir>/sidecars）。",
+            "pathPlaceholder": "留空 = <settings dir>/sidecars",
+            "management": "附屬檔案遷移",
+            "managementHelp": "在「與模型檔案放在一起」與「集中儲存」之間遷移現有的 .metadata.json 附屬檔案與預覽圖片，以符合目前選擇的模式。變更模式不會自動遷移現有檔案。",
+            "migrateButton": "立即遷移附屬檔案",
+            "migratingButton": "遷移中...",
+            "migrating": "正在遷移附屬檔案...",
+            "migrateSuccess": "附屬檔案遷移完成",
+            "migrateFailed": "附屬檔案遷移失敗：{message}",
+            "migrationDeferred": "現有附屬檔案未遷移。您稍後可以在「設定 > 模型庫 > 附屬檔案儲存」中遷移它們。",
+            "confirmToCentralized": "儲存模式已變更，但現有的 .metadata.json 附屬檔案與預覽圖片不會自動遷移。要現在將它們移入集中儲存目錄嗎？您也可以稍後使用「立即遷移附屬檔案」按鈕完成。",
+            "confirmToAlongside": "儲存模式已變更，但現有的 .metadata.json 附屬檔案與預覽圖片不會自動遷移。要現在將它們移回各自的模型檔案旁邊嗎？您也可以稍後使用「立即遷移附屬檔案」按鈕完成。",
+            "confirmRelocateRoot": "集中儲存目錄已變更，但現有的附屬檔案與預覽圖片仍在原目錄中。要現在將它們移到新目錄嗎？"
+        },
         "proxySettings": {
             "enableProxy": "啟用應用程式代理",
             "enableProxyHelp": "啟用此應用程式的自訂代理設定，將覆蓋系統代理設定",
@@ -1350,6 +1373,10 @@
             "emptyNote": "該資料夾中沒有模型，其中的其他檔案也會一併刪除。",
             "notEmptyTitle": "資料夾不是空的",
             "notEmptyMessage": "該資料夾中仍有模型，請先刪除或移出這些模型 —— 刪除資料夾不會串聯刪除模型檔案。",
+            "notEmptyMessageCount": "該資料夾中仍有 {count} 個模型檔案，請先刪除或移出這些模型 —— 刪除資料夾不會串聯刪除模型檔案。",
+            "notEmptyMessageExcluded": "該資料夾中仍有 {count} 個模型檔案，其中 {excluded} 個已從模型庫中排除。請先在「管理已排除的模型」中取消排除並刪除它們 —— 刪除資料夾不會串聯刪除模型檔案。",
+            "busyTitle": "仍有刪除操作待處理",
+            "checking": "正在檢查資料夾內容...",
             "confirm": "刪除資料夾"
         },
         "deleteFolderResult": {
@@ -1358,6 +1385,7 @@
             "restored": "資料夾已還原",
             "failed": "刪除資料夾失敗: {message}",
             "notEmpty": "該資料夾中仍有模型。請重新整理側邊欄後再試。",
+            "notEmptyWithCount": "該資料夾中仍有 {count} 個模型檔案。請重新整理側邊欄後再試。",
             "busy": "該資料夾內仍有待處理的刪除操作，請等待復原時間結束。",
             "unsupported": "此頁面不支援刪除資料夾",
             "noRoot": "未設定模型根目錄"
@@ -1637,6 +1665,12 @@
             "titleRevert": "要還原原始檔案名稱嗎？",
             "revertButton": "還原原始檔案名稱"
         },
+        "sidecarMigrationConfirm": {
+            "titleToCentralized": "要將附屬檔案移到集中儲存嗎？",
+            "titleToAlongside": "要將附屬檔案移回模型檔案旁邊嗎？",
+            "confirmButton": "立即遷移",
+            "titleRelocateRoot": "要將附屬檔案移到新的儲存目錄嗎？"
+        },
         "bulkAddTags": {
             "title": "新增標籤到多個模型",
             "description": "新增標籤到",

py/config.py

@@ -891,6 +891,17 @@ class Config:
         if self.recipes_path:
             preview_roots.update(self._expand_preview_root(self.recipes_path))
 
+        # Centralized sidecar storage holds preview assets outside the model
+        # roots; allow serving them when the mode is active.
+        try:
+            from .utils.sidecar_paths import get_sidecar_root  # Local import to avoid circular dependency
+
+            sidecar_root = get_sidecar_root()
+        except Exception:  # pragma: no cover - defensive fallback
+            sidecar_root = ""
+        if sidecar_root:
+            preview_roots.update(self._expand_preview_root(sidecar_root))
+
         for target, link in self._path_mappings.items():
             preview_roots.update(self._expand_preview_root(target))
             preview_roots.update(self._expand_preview_root(link))
@@ -1494,6 +1505,15 @@ class Config:
         self.other_roots = self._init_other_paths()
         self._rebuild_preview_roots()
 
+    def refresh_preview_roots(self) -> None:
+        """Rebuild the preview allowlist after path-affecting settings change.
+
+        Called when ``sidecar_storage_mode`` / ``sidecar_storage_path`` are
+        updated so centralized preview assets become servable (or stop being
+        servable) without a restart.
+        """
+        self._rebuild_preview_roots()
+
     def get_other_models_availability(self) -> Dict[str, Any]:
         """Report the other-model folders the host can actually expose.
 

py/metadata_ops/__init__.py

@@ -172,12 +172,16 @@ async def download_preview(
     """
     from ..services.downloader import get_downloader
     from ..utils.exif_utils import ExifUtils
+    from ..utils.sidecar_paths import get_preview_dir
 
     if not url or not url.strip():
         return None
 
     base_name = os.path.splitext(os.path.basename(model_path))[0]
-    preview_dir = os.path.dirname(model_path)
+    preview_dir = get_preview_dir(model_path)
+    # Centralized mirrors may not exist yet (unlike the model's own directory
+    # in alongside mode).
+    os.makedirs(preview_dir, exist_ok=True)
     output_path = os.path.join(preview_dir, base_name + ".webp")
 
     downloader = await get_downloader()

py/routes/handlers/misc_handlers.py

@@ -45,6 +45,8 @@ from ...services.llm_service import (
     get_provider_model_ids,
 )
 from ...services.cache_health_monitor import CacheHealthMonitor, CacheHealthStatus
+from ...services.use_cases.sidecar_migration_use_case import SidecarMigrationUseCase
+from ...services.websocket_progress_callback import WebSocketBroadcastCallback
 from ...utils.models import BaseModelMetadata
 from ...utils.constants import (
     CIVITAI_USER_MODEL_TYPES,
@@ -68,6 +70,7 @@ from ...utils.example_images_paths import (
 )
 from ...utils.lora_metadata import extract_trained_words
 from ...utils.session_logging import get_standalone_session_log_snapshot
+from ...utils.sidecar_paths import get_metadata_path, get_preview_dir
 from ...utils.usage_stats import UsageStats
 from .base_model_handlers import BaseModelHandlerSet
 
@@ -943,15 +946,24 @@ class DoctorHandler:
 
                             os.rename(path, new_path)
 
-                            for suffix in (".metadata.json", ".civitai.info"):
+                            old_metadata_path = get_metadata_path(path)
-                                old_sidecar = old_base_no_ext + suffix
+                            new_metadata_path = get_metadata_path(new_path)
-                                new_sidecar = new_base_no_ext + suffix
+                            if os.path.exists(old_metadata_path):
+                                os.rename(old_metadata_path, new_metadata_path)
+
+                            old_sidecar = old_base_no_ext + ".civitai.info"
+                            new_sidecar = new_base_no_ext + ".civitai.info"
                             if os.path.exists(old_sidecar):
                                 os.rename(old_sidecar, new_sidecar)
 
                             for preview_ext in PREVIEW_EXTENSIONS:
-                                old_preview = old_base_no_ext + preview_ext
+                                old_preview = os.path.join(
-                                new_preview = new_base_no_ext + preview_ext
+                                    get_preview_dir(path), base_name + preview_ext
+                                )
+                                new_preview = os.path.join(
+                                    get_preview_dir(new_path),
+                                    candidate_base + preview_ext,
+                                )
                                 if os.path.exists(old_preview):
                                     os.rename(old_preview, new_preview)
 
@@ -963,7 +975,10 @@ class DoctorHandler:
                                     old_preview_url = entry["preview_url"].replace("\\", "/")
                                     preview_ext = os.path.splitext(old_preview_url)[1]
                                     if preview_ext:
-                                        entry["preview_url"] = (new_base_no_ext + preview_ext).replace(os.sep, "/")
+                                        entry["preview_url"] = os.path.join(
+                                            get_preview_dir(new_path),
+                                            candidate_base + preview_ext,
+                                        ).replace(os.sep, "/")
                                 await scanner.update_single_model_cache(
                                     path, new_path, entry
                                 )
@@ -4123,6 +4138,64 @@ class NodeRegistryHandler:
             return web.json_response({"success": False, "error": str(exc)}, status=500)
 
 
+class SidecarMigrationHandler:
+    """Migrate sidecar metadata and previews between storage layouts."""
+
+    _VALID_DIRECTIONS = ("to_centralized", "to_alongside", "relocate_root")
+
+    def __init__(
+        self,
+        *,
+        use_case_factory: Callable[[], SidecarMigrationUseCase] = SidecarMigrationUseCase,
+        progress_callback_factory: Callable[[], Any] = WebSocketBroadcastCallback,
+    ) -> None:
+        self._use_case_factory = use_case_factory
+        self._progress_callback_factory = progress_callback_factory
+
+    async def migrate_sidecars(self, request: web.Request) -> web.Response:
+        """Run a sidecar migration; accepts POST JSON or GET query params."""
+        try:
+            if request.method == "GET":
+                params: Mapping[str, Any] = request.query
+            else:
+                try:
+                    params = await request.json()
+                except Exception:  # empty/invalid body: fall back to query
+                    params = request.query
+
+            direction = str(params.get("direction") or "").strip()
+            if direction not in self._VALID_DIRECTIONS:
+                return web.json_response(
+                    {
+                        "success": False,
+                        "error": "direction must be 'to_centralized', 'to_alongside' or 'relocate_root'",
+                    },
+                    status=400,
+                )
+
+            force = params.get("force") in (True, 1, "true", "1")
+            old_root = str(params.get("old_root") or "").strip()
+            if direction == "relocate_root" and not old_root:
+                return web.json_response(
+                    {"success": False, "error": "old_root is required for relocate_root"},
+                    status=400,
+                )
+
+            use_case = self._use_case_factory()
+            progress_cb = self._progress_callback_factory()
+            result = await use_case.execute_with_error_handling(
+                direction=direction,
+                progress_cb=progress_cb,
+                force=force,
+                old_root=old_root,
+            )
+            status = 200 if result.get("success") else 400
+            return web.json_response(result, status=status)
+        except Exception as exc:
+            logger.error("Sidecar migration failed: %s", exc, exc_info=True)
+            return web.json_response({"success": False, "error": str(exc)}, status=500)
+
+
 class MiscHandlerSet:
     """Aggregate handlers into a lookup compatible with the registrar."""
 
@@ -4149,6 +4222,7 @@ class MiscHandlerSet:
         model_source_handler: Any = None,
         agent_handler: Any = None,
         download_routing: Any = None,
+        sidecar_migration: Any = None,
     ) -> None:
         self.health = health
         self.settings = settings
@@ -4170,6 +4244,7 @@ class MiscHandlerSet:
         self.model_source_handler = model_source_handler
         self.agent_handler = agent_handler
         self.download_routing = download_routing
+        self.sidecar_migration = sidecar_migration
 
     def to_route_mapping(
         self,
@@ -4236,6 +4311,8 @@ class MiscHandlerSet:
             "cancel_agent_skill": self.agent_handler.cancel_agent_skill,
             # Download routing handler
             "get_download_routing": self.download_routing.get_download_routing,
+            # Sidecar migration handler
+            "migrate_sidecars": self.sidecar_migration.migrate_sidecars,
             # Base model handlers
             "get_base_models": self.base_model.get_base_models,
             "refresh_base_models": self.base_model.refresh_base_models,

py/routes/handlers/model_handlers.py

@@ -50,6 +50,7 @@ from ...services.errors import RateLimitError, ResourceNotFoundError
 from ...utils.civitai_utils import resolve_license_payload
 from ...utils.file_utils import calculate_sha256
 from ...utils.metadata_manager import MetadataManager
+from ...utils.sidecar_paths import get_metadata_path
 from ...utils.url_utils import relative_root_prefix
 
 LICENSE_FIELDS = (
@@ -676,7 +677,7 @@ class ModelManagementHandler:
                     status=400,
                 )
 
-            metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+            metadata_path = get_metadata_path(file_path)
             local_metadata = await self._metadata_sync.load_local_metadata(
                 metadata_path
             )

py/routes/misc_route_registrar.py

@@ -113,6 +113,13 @@ MISC_ROUTE_DEFINITIONS: tuple[RouteDefinition, ...] = (
     RouteDefinition(
         "POST", "/api/lm/download/routing", "get_download_routing"
     ),
+    # Sidecar storage layout migration (GET supported for the extension)
+    RouteDefinition(
+        "POST", "/api/lm/sidecars/migrate", "migrate_sidecars"
+    ),
+    RouteDefinition(
+        "GET", "/api/lm/sidecars/migrate", "migrate_sidecars"
+    ),
     RouteDefinition(
         "POST", "/api/lm/download-model-source", "download_model_source"
     ),

py/routes/misc_routes.py

@@ -32,6 +32,7 @@ from .handlers.misc_handlers import (
     NodeRegistry,
     NodeRegistryHandler,
     SettingsHandler,
+    SidecarMigrationHandler,
     SupportersHandler,
     TrainedWordsHandler,
     UsageStatsHandler,
@@ -142,6 +143,7 @@ class MiscRoutes:
         model_source_handler = ModelSourceHandler()
         agent_handler = AgentHandler()
         download_routing = DownloadRoutingHandler()
+        sidecar_migration = SidecarMigrationHandler()
 
         return self._handler_set_factory(
             health=health,
@@ -164,6 +166,7 @@ class MiscRoutes:
             model_source_handler=model_source_handler,
             agent_handler=agent_handler,
             download_routing=download_routing,
+            sidecar_migration=sidecar_migration,
         )
 
 

py/services/autov3_backfill_service.py

@@ -27,6 +27,8 @@ import os
 import threading
 from typing import TYPE_CHECKING, Optional
 
+from ..utils.sidecar_paths import get_metadata_path
+
 if TYPE_CHECKING:  # pragma: no cover - type-check only; runtime imports are local
     from .model_scanner import ModelScanner
 
@@ -41,7 +43,7 @@ def _resolve_autov3(file_path: str) -> str:
     safetensors header hash. Returns ``''`` when neither is available.
     """
     try:
-        metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
+        metadata_path = get_metadata_path(file_path)
         if os.path.exists(metadata_path):
             with open(metadata_path, "r", encoding="utf-8") as handle:
                 payload = json.load(handle)

py/services/checkpoint_scanner.py

@@ -12,6 +12,7 @@ from typing import Any, Dict, List, Optional
 from ..utils.models import CheckpointMetadata
 from ..utils.file_utils import find_preview_file, normalize_path, calculate_autov3
 from ..utils.metadata_manager import MetadataManager
+from ..utils.sidecar_paths import get_preview_dir, is_centralized
 from ..config import config
 from .model_scanner import ModelScanner, _is_excluded_dir
 from .model_hash_index import ModelHashIndex
@@ -61,10 +62,9 @@ class CheckpointScanner(ModelScanner):
                 return None
 
             base_name = os.path.splitext(os.path.basename(file_path))[0]
-            dir_path = os.path.dirname(file_path)
 
             # Find preview image
-            preview_url = find_preview_file(base_name, dir_path)
+            preview_url = find_preview_file(base_name, get_preview_dir(file_path))
 
             # AutoV3 reads only the safetensors header, so it is cheap even for
             # large checkpoints; record the checked state at creation time ("" =
@@ -322,6 +322,11 @@ class CheckpointScanner(ModelScanner):
 
     async def _find_pending_models_from_filesystem(self) -> List[Dict[str, Any]]:
         """Scan filesystem for checkpoint metadata files with pending hash status."""
+        # Centralized mode stores sidecars in the mirror tree, not next to the
+        # models; walk the mirror instead of the model folders.
+        if is_centralized():
+            return self._find_pending_models_in_sidecar_mirror()
+
         pending_models = []
 
         for root_path in self.get_model_roots():

py/services/download_manager.py

@@ -38,6 +38,7 @@ from ..utils.preview_selection import resolve_mature_threshold, select_preview_m
 from ..utils.utils import calculate_filename_for_model, sanitize_folder_name
 from ..utils.exif_utils import ExifUtils
 from ..utils.metadata_manager import MetadataManager
+from ..utils.sidecar_paths import get_metadata_path, get_preview_dir
 from .service_registry import ServiceRegistry
 from .download_routing import is_diffusion_model_download, resolve_other_download_sub_type
 from .settings_manager import get_settings_manager
@@ -831,7 +832,7 @@ class DownloadManager:
                 )
 
         for file_path in target_files:
-            metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+            metadata_path = get_metadata_path(file_path)
             deleted = await self._delete_file_with_retries(metadata_path)
             if not deleted and os.path.exists(metadata_path):
                 logger.error(f"Error deleting metadata file: {metadata_path}")
@@ -2447,7 +2448,7 @@ class DownloadManager:
                 return {"success": False, "error": save_path}
 
             part_path = save_path + ".part"
-            metadata_path = os.path.splitext(save_path)[0] + ".metadata.json"
+            metadata_path = get_metadata_path(save_path)
 
             pause_control = self._pause_events.get(download_id) if download_id else None
 
@@ -2464,6 +2465,10 @@ class DownloadManager:
             # Download preview image if available
             images = version_info.get("images", [])
             if images:
+                # Centralized preview mirrors may not exist yet (unlike the
+                # model's own directory in alongside mode).
+                os.makedirs(get_preview_dir(save_path), exist_ok=True)
+
                 if progress_callback:
                     await progress_callback(
                         1
@@ -2503,7 +2508,10 @@ class DownloadManager:
 
                     if media_type == "video":
                         preview_ext = _extension_from_url(preview_url, ".mp4")
-                        preview_path = os.path.splitext(save_path)[0] + preview_ext
+                        preview_path = os.path.join(
+                            get_preview_dir(save_path),
+                            os.path.splitext(os.path.basename(save_path))[0] + preview_ext,
+                        )
                         rewritten_url, rewritten = rewrite_preview_url(
                             preview_url, media_type="video"
                         )
@@ -2530,7 +2538,10 @@ class DownloadManager:
                         )
                         if rewritten and rewritten_url:
                             preview_ext = _extension_from_url(preview_url, ".png")
-                            preview_path = os.path.splitext(save_path)[0] + preview_ext
+                            preview_path = os.path.join(
+                                get_preview_dir(save_path),
+                                os.path.splitext(os.path.basename(save_path))[0] + preview_ext,
+                            )
                             success, _ = await downloader.download_file(
                                 rewritten_url, preview_path, use_auth=False
                             )
@@ -2557,8 +2568,9 @@ class DownloadManager:
                                         temp_file_handle.write(
                                             content if isinstance(content, bytes) else content.encode("utf-8")
                                         )
-                                    preview_path = (
+                                    preview_path = os.path.join(
-                                        os.path.splitext(save_path)[0] + ".webp"
+                                        get_preview_dir(save_path),
+                                        os.path.splitext(os.path.basename(save_path))[0] + ".webp",
                                     )
 
                                     optimized_data, _ = ExifUtils.optimize_image(
@@ -2788,9 +2800,7 @@ class DownloadManager:
                             entry = cast(Any, adjusted_entry)
                             metadata_entries[index] = entry
 
-                metadata_file_path = (
+                metadata_file_path = get_metadata_path(entry.file_path)
-                    os.path.splitext(entry.file_path)[0] + ".metadata.json"
-                )
                 metadata_files_for_cleanup.append(metadata_file_path)
 
                 await MetadataManager.save_metadata(entry.file_path, entry)
@@ -3049,7 +3059,11 @@ class DownloadManager:
         extension = os.path.splitext(preview_path)[1] or ".webp"
 
         targets = [
-            os.path.splitext(entry.file_path)[0] + extension for entry in entries
+            os.path.join(
+                get_preview_dir(entry.file_path),
+                os.path.splitext(os.path.basename(entry.file_path))[0] + extension,
+            )
+            for entry in entries
         ]
 
         if not targets:
@@ -3057,10 +3071,12 @@ class DownloadManager:
 
         first_target = targets[0]
         if preview_path != first_target:
+            os.makedirs(os.path.dirname(first_target), exist_ok=True)
             os.replace(preview_path, first_target)
         source_path = first_target
 
         for target in targets[1:]:
+            os.makedirs(os.path.dirname(target), exist_ok=True)
             shutil.copyfile(source_path, target)
 
         return targets

py/services/metadata_sync_service.py

@@ -12,6 +12,7 @@ from ..services.settings_manager import SettingsManager
 from ..utils.civitai_utils import resolve_license_payload
 from ..utils.model_utils import determine_base_model
 from ..utils.models import autov3_from_civitai_files
+from ..utils.sidecar_paths import get_metadata_path
 from .connectivity_guard import OFFLINE_FRIENDLY_MESSAGE, is_expected_offline_error
 from .errors import RateLimitError
 from .model_sources import has_external_source
@@ -216,7 +217,7 @@ class MetadataSyncService:
             logger.error(error)
             return False, error
 
-        metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+        metadata_path = get_metadata_path(file_path)
         enable_archive = self._settings.get("enable_metadata_archive_db", False)
         previous_source = model_data.get("metadata_source") or (model_data.get("civitai") or {}).get("source")
 
@@ -485,7 +486,7 @@ class MetadataSyncService:
                 + (f" with version: {model_version_id}" if model_version_id else "")
             )
 
-        metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+        metadata_path = get_metadata_path(file_path)
         await self.update_model_metadata(
             metadata_path,
             metadata,
@@ -505,7 +506,7 @@ class MetadataSyncService:
     ) -> Dict[str, Any]:
         """Apply metadata updates and persist to disk and cache."""
 
-        metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+        metadata_path = get_metadata_path(file_path)
         metadata = await metadata_loader(metadata_path)
 
         for key, value in updates.items():
@@ -554,7 +555,7 @@ class MetadataSyncService:
         }
 
         expected_hash: Optional[str] = None
-        first_metadata_path = os.path.splitext(file_paths[0])[0] + ".metadata.json"
+        first_metadata_path = get_metadata_path(file_paths[0])
         first_metadata = await metadata_loader(first_metadata_path)
         if first_metadata and "sha256" in first_metadata:
             expected_hash = first_metadata["sha256"].lower()
@@ -565,7 +566,7 @@ class MetadataSyncService:
 
             try:
                 actual_hash = await hash_calculator(path)
-                metadata_path = os.path.splitext(path)[0] + ".metadata.json"
+                metadata_path = get_metadata_path(path)
                 metadata = await metadata_loader(metadata_path)
                 stored_hash = metadata.get("sha256", "").lower()
 

py/services/model_file_service.py

@@ -8,6 +8,7 @@ from abc import ABC, abstractmethod
 
 from ..utils.utils import calculate_relative_path_for_model, remove_empty_dirs
 from ..utils.constants import AUTO_ORGANIZE_BATCH_SIZE, MODEL_FILE_EXTENSIONS
+from ..utils.sidecar_paths import is_centralized, resolve_centralized_dir_for_dir
 from ..services.settings_manager import get_settings_manager
 from ..services.model_lifecycle_service import _require_path_in_library_roots
 from ..services.pending_delete_service import PENDING_DELETE_DIR_NAME
@@ -15,6 +16,16 @@ from ..services.pending_delete_service import PENDING_DELETE_DIR_NAME
 logger = logging.getLogger(__name__)
 
 
+def _normalize_match_path(path: Any) -> str:
+    """Normalize a path for set membership tests.
+
+    Business paths only — symlinks are never resolved here, matching how the
+    scanner stores ``excluded_models``. The forward-slash form keeps Windows
+    comparisons working with the scanner's normalized entries.
+    """
+    return os.path.normpath(os.path.abspath(str(path))).replace(os.sep, "/")
+
+
 class ProgressCallback(ABC):
     """Abstract callback interface for progress reporting"""
     
@@ -567,8 +578,9 @@ class ModelMoveService:
 
         Returns:
             Dictionary with the success flag plus a removal manifest
-            (``model_count``/``file_count``/``dir_count``/``symlink_count``/
+            (``model_count``/``excluded_model_count``/``file_count``/
-            ``total_bytes``/``restorable``) on success.
+            ``dir_count``/``symlink_count``/``total_bytes``/``restorable``)
+            on success.
         """
         try:
             if not folder_path or not str(folder_path).strip():
@@ -608,13 +620,34 @@ class ModelMoveService:
                 }
 
             if manifest["model_count"] > 0:
+                model_count = manifest["model_count"]
+                excluded_count = manifest["excluded_model_count"]
+                # Excluded models are hidden from the library lists but are
+                # still real weight files, so they block the cascade just like
+                # any other model. Naming them is what makes the refusal
+                # actionable: the folder looks empty in the sidebar precisely
+                # because everything in it is excluded.
+                if excluded_count == model_count:
+                    error = (
+                        f"Folder still contains {model_count} model file(s), "
+                        "all excluded from the library; un-exclude or delete "
+                        "them first"
+                    )
+                elif excluded_count:
+                    error = (
+                        f"Folder still contains {model_count} model file(s), "
+                        f"{excluded_count} of them excluded from the library; "
+                        "delete or move them first"
+                    )
+                else:
+                    error = (
+                        f"Folder still contains {model_count} model "
+                        "file(s); delete or move them first"
+                    )
                 return {
                     "success": False,
                     "code": "not_empty",
-                    "error": (
+                    "error": error,
-                        f"Folder still contains {manifest['model_count']} model "
-                        "file(s); delete or move them first"
-                    ),
                     "manifest": manifest,
                 }
 
@@ -631,6 +664,21 @@ class ModelMoveService:
 
             shutil.rmtree(absolute_path)
 
+            # Centralized mode: prune the folder's mirror subtree when it no
+            # longer holds any sidecar files (per-model deletes already
+            # removed their sidecars, so only empty directories are expected;
+            # a non-empty mirror keeps its orphan sidecars).
+            if is_centralized():
+                mirror_dir = resolve_centralized_dir_for_dir(absolute_path)
+                if mirror_dir and os.path.isdir(mirror_dir):
+                    for root, _dirs, files in os.walk(mirror_dir, topdown=False):
+                        if files:
+                            continue
+                        try:
+                            os.rmdir(root)
+                        except OSError:  # pragma: no cover - best-effort cleanup
+                            pass
+
             await self._forget_folder(relative_folder)
 
             return {
@@ -667,13 +715,20 @@ class ModelMoveService:
         Symbolic links are never followed (``os.walk`` default) and are counted
         separately — ``shutil.rmtree`` unlinks them without touching their
         targets.
+
+        ``excluded_model_count`` splits the subset of ``model_count`` that the
+        library hides behind the ``exclude`` flag: those files still block the
+        delete, yet they are invisible to the model lists (and therefore to the
+        folder tree, which derives "empty" from them).
         """
         model_count = 0
+        excluded_model_count = 0
         file_count = 0
         dir_count = 0
         symlink_count = 0
         total_bytes = 0
         pending_delete_job = False
+        excluded_paths = self._excluded_model_paths()
 
         for dirpath, dirnames, filenames in os.walk(absolute_path):
             if PENDING_DELETE_DIR_NAME in dirnames:
@@ -692,6 +747,8 @@ class ModelMoveService:
                     continue
                 if self._is_model_file(name):
                     model_count += 1
+                    if _normalize_match_path(full_path) in excluded_paths:
+                        excluded_model_count += 1
                 else:
                     file_count += 1
                 try:
@@ -701,6 +758,7 @@ class ModelMoveService:
 
         return {
             "model_count": model_count,
+            "excluded_model_count": excluded_model_count,
             "file_count": file_count,
             "dir_count": dir_count,
             "symlink_count": symlink_count,
@@ -716,6 +774,21 @@ class ModelMoveService:
             ),
         }
 
+    def _excluded_model_paths(self) -> Set[str]:
+        """Absolute paths of the models the library hides behind ``exclude``.
+
+        Best-effort: scanner stand-ins that do not expose the accessor simply
+        report no excluded models.
+        """
+        get_excluded = getattr(self.scanner, "get_excluded_models", None)
+        if not callable(get_excluded):
+            return set()
+        try:
+            paths = get_excluded() or []
+        except Exception:  # pragma: no cover - defensive
+            return set()
+        return {_normalize_match_path(path) for path in paths if path}
+
     async def _forget_folder(self, relative_folder: str) -> None:
         """Drop a removed directory from the scanner's folder/cache records."""
         if not relative_folder:

py/services/model_lifecycle_service.py

@@ -11,6 +11,7 @@ from ..services.service_registry import ServiceRegistry
 from ..services.pending_delete_service import get_pending_delete_service
 from ..utils.constants import PREVIEW_EXTENSIONS
 from ..utils.metadata_manager import MetadataManager
+from ..utils.sidecar_paths import get_metadata_path, get_preview_dir, get_sidecar_dir
 
 logger = logging.getLogger(__name__)
 
@@ -41,16 +42,22 @@ async def load_local_metadata(metadata_path: str) -> Dict[str, Any]:
 async def delete_model_artifacts(
     target_dir: str, file_name: str, main_extension: str | None = None
 ) -> List[str]:
-    """Delete the primary model artefacts within ``target_dir``."""
+    """Delete the primary model artefacts within ``target_dir``.
+
+    Sidecars and previews are taken from the model's sidecar directory — the
+    model's own directory in alongside mode, the centralized mirror otherwise.
+    """
 
     main_extension = ".safetensors" if main_extension is None else main_extension
     main_file = f"{file_name}{main_extension}" if main_extension else file_name
-    patterns = [main_file, f"{file_name}.metadata.json"]
+    model_path = os.path.join(target_dir, main_file)
+    sidecar_dir = get_sidecar_dir(model_path)
+    patterns = [os.path.basename(get_metadata_path(model_path))]
     for ext in PREVIEW_EXTENSIONS:
         patterns.append(f"{file_name}{ext}")
 
     deleted: List[str] = []
-    main_path = os.path.join(target_dir, main_file).replace(os.sep, "/")
+    main_path = model_path.replace(os.sep, "/")
 
     if os.path.exists(main_path):
         os.remove(main_path)
@@ -58,8 +65,8 @@ async def delete_model_artifacts(
     else:
         logger.warning("Model file not found: %s", main_file)
 
-    for pattern in patterns[1:]:
+    for pattern in patterns:
-        path = os.path.join(target_dir, pattern)
+        path = os.path.join(sidecar_dir, pattern)
         if os.path.exists(path):
             try:
                 os.remove(path)
@@ -260,7 +267,7 @@ class ModelLifecycleService:
 
         _require_path_in_library_roots(file_path, self._scanner, label="File path")
 
-        metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+        metadata_path = get_metadata_path(file_path)
         metadata = await self._metadata_loader(metadata_path)
         metadata["exclude"] = True
 
@@ -315,7 +322,7 @@ class ModelLifecycleService:
         if not os.path.exists(file_path):
             raise ValueError("Model file does not exist")
 
-        metadata_path = os.path.splitext(file_path)[0] + ".metadata.json"
+        metadata_path = get_metadata_path(file_path)
         metadata_payload = await self._metadata_loader(metadata_path)
         metadata_payload["exclude"] = False
 
@@ -384,21 +391,26 @@ class ModelLifecycleService:
         if os.path.exists(new_file_path):
             raise ValueError("A file with this name already exists")
 
-        patterns = [
+        metadata_filename = os.path.basename(get_metadata_path(file_path))
-            f"{old_file_name}{old_extension}",
+        # Sidecars/previews live in the sidecar dir (the model's own dir in
-            f"{old_file_name}.metadata.json",
+        # alongside mode, the centralized mirror otherwise); the model file
-            f"{old_file_name}.metadata.json.bak",
+        # itself always stays in target_dir.
+        sidecar_dir = get_sidecar_dir(file_path)
+        patterns: List[tuple[str, str]] = [
+            (target_dir, f"{old_file_name}{old_extension}"),
+            (sidecar_dir, metadata_filename),
+            (sidecar_dir, f"{metadata_filename}.bak"),
         ]
         for ext in PREVIEW_EXTENSIONS:
-            patterns.append(f"{old_file_name}{ext}")
+            patterns.append((sidecar_dir, f"{old_file_name}{ext}"))
 
         existing_files: List[tuple[str, str]] = []
-        for pattern in patterns:
+        for pattern_dir, pattern in patterns:
-            path = os.path.join(target_dir, pattern)
+            path = os.path.join(pattern_dir, pattern)
             if os.path.exists(path):
                 existing_files.append((path, pattern))
 
-        metadata_path = os.path.join(target_dir, f"{old_file_name}.metadata.json")
+        metadata_path = get_metadata_path(file_path)
         metadata: Optional[Dict[str, object]] = None
         hash_value: Optional[str] = None
 
@@ -413,9 +425,9 @@ class ModelLifecycleService:
 
         for old_path, pattern in existing_files:
             ext = self._get_multipart_ext(pattern)
-            new_path = os.path.join(target_dir, f"{new_file_name}{ext}").replace(
+            new_path = os.path.join(
-                os.sep, "/"
+                os.path.dirname(old_path), f"{new_file_name}{ext}"
-            )
+            ).replace(os.sep, "/")
             os.rename(old_path, new_path)
             renamed_files.append(new_path)
 
@@ -432,9 +444,9 @@ class ModelLifecycleService:
             if metadata.get("preview_url"):
                 old_preview = str(metadata["preview_url"])
                 ext = self._get_multipart_ext(old_preview)
-                new_preview = os.path.join(target_dir, f"{new_file_name}{ext}").replace(
+                new_preview = os.path.join(
-                    os.sep, "/"
+                    get_preview_dir(new_file_path), f"{new_file_name}{ext}"
-                )
+                ).replace(os.sep, "/")
                 metadata["preview_url"] = new_preview
 
             await self._metadata_manager.save_metadata(new_file_path, metadata)

py/services/model_scanner.py

@@ -11,6 +11,13 @@ from ..utils.models import BaseModelMetadata, autov3_from_civitai_files
 from ..config import config
 from ..utils.file_utils import find_preview_file, get_preview_extension, calculate_sha256, calculate_autov3
 from ..utils.metadata_manager import MetadataManager
+from ..utils.sidecar_paths import (
+    get_metadata_path,
+    get_preview_dir,
+    get_sidecar_dir,
+    is_centralized,
+    resolve_centralized_dir_for_dir,
+)
 from ..utils.civitai_utils import resolve_license_info
 from .model_cache import ModelCache
 from .model_hash_index import ModelHashIndex
@@ -1613,6 +1620,25 @@ class ModelScanner:
         old_abs_prefix = f"{str(previous_path).replace(chr(92), '/').rstrip('/')}/"
         new_abs_prefix = f"{str(new_path).replace(chr(92), '/').rstrip('/')}/"
 
+        # Centralized sidecar mode: sidecars/previews live in the mirror tree,
+        # not under the renamed model directory, so the mirror subtree must
+        # move too and mirror-prefixed preview URLs need their own rekey.
+        old_mirror_dir: Optional[str] = None
+        new_mirror_dir: Optional[str] = None
+        if is_centralized():
+            old_mirror_dir = resolve_centralized_dir_for_dir(str(previous_path))
+            new_mirror_dir = resolve_centralized_dir_for_dir(str(new_path))
+        old_mirror_prefix = (
+            f"{old_mirror_dir.replace(chr(92), '/').rstrip('/')}/"
+            if old_mirror_dir
+            else ""
+        )
+        new_mirror_prefix = (
+            f"{new_mirror_dir.replace(chr(92), '/').rstrip('/')}/"
+            if new_mirror_dir
+            else ""
+        )
+
         cache = self._cache
         if cache is None:
             return False
@@ -1670,8 +1696,24 @@ class ModelScanner:
                 item["preview_url"] = self._rekey_path(
                     item["preview_url"], old_abs_prefix, new_abs_prefix
                 )
+                if old_mirror_prefix:
+                    item["preview_url"] = self._rekey_path(
+                        item["preview_url"], old_mirror_prefix, new_mirror_prefix
+                    )
             touched.append(item)
 
+        if old_mirror_dir and new_mirror_dir and os.path.isdir(old_mirror_dir):
+            try:
+                os.makedirs(os.path.dirname(new_mirror_dir), exist_ok=True)
+                shutil.move(old_mirror_dir, new_mirror_dir)
+            except Exception as exc:  # pragma: no cover - defensive
+                logger.warning(
+                    "Failed to move centralized sidecar mirror %s -> %s: %s",
+                    old_mirror_dir,
+                    new_mirror_dir,
+                    exc,
+                )
+
         if touched:
             changed = True
             await self._rewrite_sidecar_paths(touched)
@@ -1700,7 +1742,9 @@ class ModelScanner:
     async def _rewrite_sidecar_paths(self, entries: List[Dict[str, Any]]) -> None:
         """Point each model's metadata sidecar at its new location.
 
-        Sidecars travel with the renamed directory, so only the recorded
+        In alongside mode sidecars travel with the renamed directory; in
+        centralized mode the mirror subtree has already been moved by the
+        caller (:meth:`rename_known_folder`). Either way only the recorded
         ``file_path``/``preview_url`` inside them need rewriting. Failures are
         logged and skipped — a stale sidecar is repaired by the next metadata
         refresh, and must not abort the rename.
@@ -1709,7 +1753,7 @@ class ModelScanner:
             file_path = item.get("file_path")
             if not file_path:
                 continue
-            metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
+            metadata_path = get_metadata_path(file_path)
             if not os.path.exists(metadata_path):
                 continue
             try:
@@ -1719,6 +1763,94 @@ class ModelScanner:
                     "Failed to rewrite metadata sidecar %s: %s", metadata_path, exc
                 )
 
+    def _find_pending_models_in_sidecar_mirror(self) -> List[Dict[str, Any]]:
+        """Mirror-tree counterpart of the alongside pending-hash filesystem scan.
+
+        Centralized mode stores ``.metadata.json`` sidecars in the mirror
+        tree, so walking the model folders finds nothing. Each mirror base is
+        resolved from a configured model root; a sidecar's recorded
+        ``file_path`` locates its model, with a stem-based probe under the
+        mapped model root as fallback (mirror path components are sanitized,
+        so reverse mapping is best-effort). Orphan sidecars whose model file
+        no longer exists are skipped, matching the alongside scan.
+        """
+
+        pending_models: List[Dict[str, Any]] = []
+
+        for root_path in self.get_model_roots():
+            mirror_base = resolve_centralized_dir_for_dir(root_path)
+            if not mirror_base or not os.path.isdir(mirror_base):
+                continue
+
+            for dirpath, dirnames, filenames in os.walk(mirror_base):
+                dirnames[:] = [d for d in dirnames if not _is_excluded_dir(d)]
+                for filename in filenames:
+                    if not filename.endswith(".metadata.json"):
+                        continue
+
+                    metadata_path = os.path.join(dirpath, filename)
+                    try:
+                        with open(metadata_path, "r", encoding="utf-8") as f:
+                            data = json.load(f)
+
+                        # Check if hash is pending
+                        hash_status = data.get("hash_status", "completed")
+                        sha256 = data.get("sha256", "")
+
+                        if hash_status != "completed" or not sha256:
+                            # Find corresponding model file: prefer the
+                            # sidecar's recorded path, then probe by stem
+                            # under the mapped model root.
+                            model_path = None
+                            recorded_path = data.get("file_path")
+                            if (
+                                isinstance(recorded_path, str)
+                                and recorded_path
+                                and os.path.exists(recorded_path)
+                            ):
+                                model_path = recorded_path
+                            else:
+                                model_name = filename.replace(".metadata.json", "")
+                                rel_dir = os.path.relpath(dirpath, mirror_base)
+                                candidate_dir = (
+                                    root_path
+                                    if rel_dir == os.curdir
+                                    else os.path.join(root_path, rel_dir)
+                                )
+                                for ext in self.file_extensions:
+                                    potential_path = os.path.join(
+                                        candidate_dir, model_name + ext
+                                    )
+                                    if os.path.exists(potential_path):
+                                        model_path = potential_path
+                                        break
+
+                            if model_path:
+                                pending_models.append(
+                                    {
+                                        "file_path": model_path.replace(os.sep, "/"),
+                                        "hash_status": hash_status,
+                                        "sha256": sha256,
+                                        **{
+                                            k: v
+                                            for k, v in data.items()
+                                            if k
+                                            not in [
+                                                "file_path",
+                                                "hash_status",
+                                                "sha256",
+                                            ]
+                                        },
+                                    }
+                                )
+                    except (json.JSONDecodeError, Exception) as e:
+                        logger.debug(
+                            f"Error reading metadata file {metadata_path}: {e}"
+                        )
+                        continue
+
+        return pending_models
+
     def _schedule_all_folders_backfill(self) -> None:
         """Kick off a one-shot background folder walk if none is running."""
         if self._all_folders_backfill_running:
@@ -1889,7 +2021,7 @@ class ModelScanner:
                         file_info['name'] = os.path.basename(file_path)
 
                         metadata = cast(Any, self.model_class).from_civitai_info(version_info, file_info, file_path)
-                        metadata.preview_url = find_preview_file(local_stem, os.path.dirname(file_path))
+                        metadata.preview_url = find_preview_file(local_stem, get_preview_dir(file_path))
                         await MetadataManager.save_metadata(file_path, metadata)
                         logger.info(f"Created metadata from .civitai.info for {file_path} (Reason: .civitai.info was found but .metadata.json was missing)")
                 except Exception as e:
@@ -2327,30 +2459,42 @@ class ModelScanner:
             source_metadata = None
             moved_metadata_path = None
 
-            # Find all files with the same base name in the source directory
+            # Associated files (sidecar metadata, previews) sit next to the
+            # model in alongside mode and in the mirror tree in centralized
+            # mode; collect from every directory that holds them.
+            source_sidecar_dir = get_sidecar_dir(source_path)
+            target_sidecar_dir = get_sidecar_dir(target_file)
+            associated_dirs = [(source_dir, target_path)]
+            if os.path.normpath(source_sidecar_dir) != os.path.normpath(source_dir):
+                associated_dirs.append((source_sidecar_dir, target_sidecar_dir))
+
+            # Find all files with the same base name in the source directories
             files_to_move = []
+            metadata_filename = os.path.basename(get_metadata_path(source_path))
+            for assoc_source_dir, assoc_target_dir in associated_dirs:
                 try:
-                for file in os.listdir(source_dir):
+                    for file in os.listdir(assoc_source_dir):
                         if file.startswith(base_name + ".") and file != os.path.basename(source_path):
-                        source_file_path = os.path.join(source_dir, file)
+                            source_file_path = os.path.join(assoc_source_dir, file)
                             # Generate new filename with the same base name as the model file
                             file_suffix = file[len(base_name):]  # Get the part after base_name (e.g., ".metadata.json", ".preview.png")
                             new_associated_filename = f"{final_base_name}{file_suffix}"
-                        target_associated_path = os.path.join(target_path, new_associated_filename)
+                            target_associated_path = os.path.join(assoc_target_dir, new_associated_filename)
 
                             # Store metadata file path for special handling
-                        if file == f"{base_name}.metadata.json":
+                            if file == metadata_filename:
                                 source_metadata = source_file_path
                                 moved_metadata_path = target_associated_path
                             else:
                                 files_to_move.append((source_file_path, target_associated_path))
                 except Exception as e:
-                logger.error(f"Error listing files in {source_dir}: {e}")
+                    logger.error(f"Error listing files in {assoc_source_dir}: {e}")
 
             # Move all associated files
             metadata = None
             for source_file, target_file_path in files_to_move:
                 try:
+                    os.makedirs(os.path.dirname(target_file_path), exist_ok=True)
                     shutil.move(source_file, target_file_path)
                 except Exception as e:
                     logger.error(f"Error moving associated file {source_file}: {e}")
@@ -2358,6 +2502,7 @@ class ModelScanner:
             # Handle metadata file specially to update paths
             if source_metadata and moved_metadata_path and os.path.exists(source_metadata):
                 try:
+                    os.makedirs(os.path.dirname(moved_metadata_path), exist_ok=True)
                     shutil.move(source_metadata, moved_metadata_path)
                     metadata = await self._update_metadata_paths(moved_metadata_path, target_file)
                 except Exception as e:
@@ -2399,7 +2544,7 @@ class ModelScanner:
             metadata['file_name'] = os.path.splitext(os.path.basename(model_path))[0]
             
             if 'preview_url' in metadata and metadata['preview_url']:
-                preview_dir = os.path.dirname(model_path)
+                preview_dir = get_preview_dir(model_path)
                 # Update preview filename to match the new base name
                 new_base_name = os.path.splitext(os.path.basename(model_path))[0]
                 preview_ext = get_preview_extension(metadata['preview_url'])
@@ -2759,7 +2904,7 @@ class ModelScanner:
 
             # Sidecar write-back: JSON null encodes the checked-unavailable
             # state. Skip silently when the sidecar does not exist.
-            metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
+            metadata_path = get_metadata_path(file_path)
             if os.path.exists(metadata_path):
                 with open(metadata_path, 'r', encoding='utf-8') as handle:
                     payload = json.load(handle)
@@ -2825,7 +2970,7 @@ class ModelScanner:
         if not file_path:
             return None
 
-        dir_path = os.path.dirname(file_path)
+        dir_path = get_preview_dir(file_path)
         base_name = os.path.splitext(os.path.basename(file_path))[0]
         preview_path = find_preview_file(base_name, dir_path)
         if preview_path:

py/services/other_scanner.py

@@ -12,6 +12,7 @@ from typing import Any, Dict, List, Optional
 from ..utils.models import OtherModelMetadata
 from ..utils.file_utils import find_preview_file, normalize_path, calculate_autov3
 from ..utils.metadata_manager import MetadataManager
+from ..utils.sidecar_paths import get_preview_dir, is_centralized
 from ..config import config
 from .model_scanner import ModelScanner, _is_excluded_dir
 from .model_hash_index import ModelHashIndex
@@ -72,10 +73,9 @@ class OtherScanner(ModelScanner):
                 return None
 
             base_name = os.path.splitext(os.path.basename(file_path))[0]
-            dir_path = os.path.dirname(file_path)
 
             # Find preview image
-            preview_url = find_preview_file(base_name, dir_path)
+            preview_url = find_preview_file(base_name, get_preview_dir(file_path))
 
             # AutoV3 reads only the safetensors header, so it is cheap even for
             # large files; record the checked state at creation time ("" =
@@ -333,6 +333,11 @@ class OtherScanner(ModelScanner):
 
     async def _find_pending_models_from_filesystem(self) -> List[Dict[str, Any]]:
         """Scan filesystem for other-model metadata files with pending hash status."""
+        # Centralized mode stores sidecars in the mirror tree, not next to the
+        # models; walk the mirror instead of the model folders.
+        if is_centralized():
+            return self._find_pending_models_in_sidecar_mirror()
+
         pending_models = []
 
         for root_path in self.get_model_roots():

py/services/pending_delete_service.py

@@ -38,6 +38,7 @@ from typing import (
 )
 
 from ..utils.constants import PREVIEW_EXTENSIONS
+from ..utils.sidecar_paths import get_metadata_path, get_sidecar_dir
 from ..utils import settings_paths
 
 logger = logging.getLogger(__name__)
@@ -669,13 +670,22 @@ class PendingDeleteService:
         """Enumerate existing artifacts exactly like delete_model_artifacts."""
         main_extension = ".safetensors" if main_extension is None else main_extension
         main_file = f"{file_name}{main_extension}" if main_extension else file_name
-        patterns = [main_file, f"{file_name}.metadata.json"]
+        model_path = os.path.join(target_dir, main_file)
+
+        artifacts: List[str] = []
+        main_path = os.path.abspath(model_path)
+        if os.path.exists(main_path):
+            artifacts.append(main_path)
+
+        # Sidecars/previews live in the sidecar dir (the model's own dir in
+        # alongside mode, the centralized mirror otherwise).
+        sidecar_dir = get_sidecar_dir(model_path)
+        patterns = [os.path.basename(get_metadata_path(model_path))]
         for ext in PREVIEW_EXTENSIONS:
             patterns.append(f"{file_name}{ext}")
 
-        artifacts: List[str] = []
         for pattern in patterns:
-            path = os.path.abspath(os.path.join(target_dir, pattern))
+            path = os.path.abspath(os.path.join(sidecar_dir, pattern))
             if os.path.exists(path):
                 artifacts.append(path)
         return artifacts
@@ -694,7 +704,9 @@ class PendingDeleteService:
         """
         for original_path in artifacts:
             staged_path = os.path.join(batch_dir, os.path.basename(original_path))
-            os.rename(original_path, staged_path)
+            # EXDEV-tolerant: centralized sidecars may live on a different
+            # filesystem than the staging batch dir under the model root.
+            self._restore_file(original_path, staged_path)
             staged_pairs.append(
                 {
                     "staged": os.path.abspath(staged_path),
@@ -736,13 +748,14 @@ class PendingDeleteService:
         return staged_pairs
 
     def _restore_file(self, staged_path: str, original_path: str) -> None:
-        """Restore a staged file to its original path, tolerating EXDEV.
+        """Move a file between staging and library paths, tolerating EXDEV.
 
         ``os.rename`` is atomic and preferred (model staging and most recipe
         restores are same-volume). Recipe staging copies into the settings-dir
-        staging parent, which may live on a DIFFERENT filesystem than the
+        staging parent, and centralized sidecars live under the configured
-        recipes dir; rename then raises EXDEV. Fall back to ``shutil.copy2`` +
+        sidecar root; both may live on a DIFFERENT filesystem than the target
-        ``os.remove`` so the bytes are restored and the staged copy removed.
+        dir, so rename can raise EXDEV. Fall back to ``shutil.copy2`` +
+        ``os.remove`` so the bytes are moved and the source copy removed.
         """
         try:
             os.rename(staged_path, original_path)
@@ -764,7 +777,10 @@ class PendingDeleteService:
             if not os.path.exists(staged_path):
                 continue
             try:
-                os.rename(staged_path, original_path)
+                # EXDEV-tolerant: centralized sidecars may have been copied
+                # across filesystems into staging, so plain os.rename would
+                # fail here and strand the only copy.
+                self._restore_file(staged_path, original_path)
             except OSError as exc:  # pragma: no cover - best-effort rollback
                 logger.warning(
                     "Failed to roll back staged file %s -> %s: %s",

py/services/preview_asset_service.py

@@ -10,6 +10,7 @@ from urllib.parse import urlparse
 from ..utils.constants import CARD_PREVIEW_WIDTH, PREVIEW_EXTENSIONS
 from ..utils.civitai_utils import rewrite_preview_url
 from ..utils.preview_selection import resolve_mature_threshold, select_preview_media
+from ..utils.sidecar_paths import get_metadata_path, get_preview_dir
 from .settings_manager import get_settings_manager
 
 logger = logging.getLogger(__name__)
@@ -63,6 +64,9 @@ class PreviewAssetService:
 
         base_name = os.path.splitext(os.path.splitext(os.path.basename(metadata_path))[0])[0]
         preview_dir = os.path.dirname(metadata_path)
+        # Centralized mirrors may not exist yet (unlike the model's own
+        # directory in alongside mode).
+        os.makedirs(preview_dir, exist_ok=True)
         is_video = first_preview.get("type") == "video"
         preview_url = first_preview.get("url")
 
@@ -159,7 +163,10 @@ class PreviewAssetService:
         """Replace an existing preview asset for a model."""
 
         base_name = os.path.splitext(os.path.basename(model_path))[0]
-        folder = os.path.dirname(model_path)
+        folder = get_preview_dir(model_path)
+        # Centralized mirrors may not exist yet (unlike the model's own
+        # directory in alongside mode).
+        os.makedirs(folder, exist_ok=True)
 
         extension, optimized_data = await self._convert_preview(
             preview_data, content_type, original_filename
@@ -179,7 +186,7 @@ class PreviewAssetService:
         with open(preview_path, "wb") as handle:
             handle.write(optimized_data)
 
-        metadata_path = os.path.splitext(model_path)[0] + ".metadata.json"
+        metadata_path = get_metadata_path(model_path)
         metadata = await metadata_loader(metadata_path)
         metadata["preview_url"] = preview_path
         metadata["preview_nsfw_level"] = nsfw_level

py/services/settings_manager.py

@@ -99,6 +99,8 @@ DEFAULT_SETTINGS: Dict[str, Any] = {
     "enable_other_models": False,
     "enabled_other_sub_types": list(DEFAULT_ENABLED_OTHER_SUB_TYPES),
     "recipes_path": "",
+    "sidecar_storage_mode": "alongside",
+    "sidecar_storage_path": "",
     "base_model_path_mappings": {},
     "download_path_templates": {},
     "download_filename_templates": {},
@@ -1616,9 +1618,30 @@ class SettingsManager:
 
         return os.path.abspath(os.path.normpath(os.path.expanduser(stripped)))
 
+    @staticmethod
+    def _normalize_sidecar_storage_mode(value: Any) -> str:
+        """Return a valid sidecar storage mode, falling back to ``alongside``."""
+
+        if isinstance(value, str):
+            normalized = value.strip().lower()
+            if normalized in ("alongside", "centralized"):
+                return normalized
+        return "alongside"
+
+    def _refresh_sidecar_storage_config(self) -> None:
+        """Rebuild dependent config state after sidecar storage settings change."""
+
+        try:
+            from ..config import config  # Local import to avoid circular dependency
+
+            config.refresh_preview_roots()
+        except Exception as exc:  # pragma: no cover - defensive logging
+            logger.debug(
+                "Failed to refresh config after sidecar storage change: %s", exc
+            )
+
     def _get_effective_recipes_dir(self, recipes_path: Optional[str] = None) -> str:
         """Resolve the effective recipes directory for the active library."""
-
         normalized_custom = self._normalize_recipes_path_value(
             self.settings.get("recipes_path", "")
             if recipes_path is None
@@ -1815,6 +1838,10 @@ class SettingsManager:
             target_recipes_dir = self._get_effective_recipes_dir(value)
             self._validate_recipes_storage_path(target_recipes_dir)
             self._migrate_recipes_directory(current_recipes_dir, target_recipes_dir)
+        elif key == "sidecar_storage_mode":
+            value = self._normalize_sidecar_storage_mode(value)
+        elif key == "sidecar_storage_path":
+            value = self._normalize_recipes_path_value(value)
         self.settings[key] = value
         portable_switch_pending = False
         if key == "use_portable_settings" and isinstance(value, bool):
@@ -1845,6 +1872,8 @@ class SettingsManager:
         self._save_settings()
         if key == "recipes_path":
             self._notify_library_change(self.get_active_library_name())
+        if key in ("sidecar_storage_mode", "sidecar_storage_path"):
+            self._refresh_sidecar_storage_config()
         if key in ("enable_other_models", "enabled_other_sub_types"):
             self._apply_other_model_settings_change()
         if portable_switch_pending:

py/services/tag_update_service.py

@@ -2,10 +2,9 @@
 
 from __future__ import annotations
 
-import os
-
 from typing import Awaitable, Callable, Dict, List, Sequence, Tuple
 
+from ..utils.sidecar_paths import get_metadata_path
 from .auto_tag_service import extract_auto_tags
 
 
@@ -24,8 +23,7 @@ class TagUpdateService:
         update_cache: Callable[[str, str, Dict[str, object]], Awaitable[bool]],
     ) -> Tuple[List[str], List[str]]:
         """Add tags to a metadata entry and return updated tags and auto_tags."""
-        base, _ = os.path.splitext(file_path)
+        metadata_path = get_metadata_path(file_path)
-        metadata_path = f"{base}.metadata.json"
         metadata = await metadata_loader(metadata_path)
 
         raw_tags = metadata.get("tags", [])

py/services/use_cases/__init__.py

@@ -21,6 +21,10 @@ from .example_images import (
     ImportExampleImagesValidationError,
 )
 from .filename_template_use_case import FilenameTemplateUseCase
+from .sidecar_migration_use_case import (
+    SidecarMigrationProgressReporter,
+    SidecarMigrationUseCase,
+)
 
 __all__ = [
     "AutoOrganizeInProgressError",
@@ -36,4 +40,6 @@ __all__ = [
     "ImportExampleImagesUseCase",
     "ImportExampleImagesValidationError",
     "FilenameTemplateUseCase",
+    "SidecarMigrationProgressReporter",
+    "SidecarMigrationUseCase",
 ]

py/services/use_cases/filename_template_use_case.py

@@ -12,6 +12,7 @@ import os
 from typing import Any, Awaitable, Callable, Dict, List, Optional, Sequence
 
 from ...utils.constants import AUTO_ORGANIZE_BATCH_SIZE
+from ...utils.sidecar_paths import get_metadata_path
 from ...utils.utils import calculate_filename_for_model
 from ..model_file_service import AutoOrganizeResult, ProgressCallback
 from ..model_lifecycle_service import ModelLifecycleService, load_local_metadata
@@ -200,7 +201,7 @@ class FilenameTemplateUseCase:
         sidecar or no ``original_file_name`` entry exists (models never
         renamed, or renamed before the recording shipped).
         """
-        metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
+        metadata_path = get_metadata_path(file_path)
         metadata = await self._metadata_loader(metadata_path)
         original = metadata.get("original_file_name")
         if not isinstance(original, str):

py/services/use_cases/sidecar_migration_use_case.py

@@ -0,0 +1,685 @@
+"""Use case migrating sidecar metadata and previews between storage layouts.
+
+Two storage layouts exist (see :mod:`py.utils.sidecar_paths`):
+
+- ``alongside``: ``<model_dir>/<name>.metadata.json`` and preview files live
+  next to the model file.
+- ``centralized``: the same files live under the configured sidecar root,
+  mirroring the library-relative directory structure.
+
+This use case moves the ``.metadata.json`` sidecar and preview files for every
+known model from one layout to the other. Model files themselves NEVER move.
+Paths inside the moved sidecar (``file_path``, ``file_name``, ``preview_url``)
+are rewritten the same way :meth:`ModelScanner._update_metadata_paths` does.
+After the move, scanner caches are reconciled so the list API immediately
+serves the new preview locations instead of stale pre-migration URLs.
+
+Intended flow (settings-first):
+
+1. The user switches ``sidecar_storage_mode`` (and optionally
+   ``sidecar_storage_path``) in settings.
+2. The migration runs in the direction of the NEW mode with ``force=True``.
+   After the switch, files in the OLD layout are the source of truth; the
+   guard below would otherwise refuse to run because the active mode already
+   matches the migration target.
+
+Both orderings work because all path computations are mode-independent: the
+alongside location is derived from the model path directly, and the mirror
+location is resolved via ``get_configured_sidecar_root()``, which ignores the
+active mode.
+
+Guards (pass ``force=True`` to bypass):
+
+- ``migrate_to_centralized`` refuses when centralized storage is already the
+  active, resolvable mode.
+- ``migrate_to_alongside`` refuses when the active mode is ``alongside``.
+"""
+
+from __future__ import annotations
+
+import errno
+import json
+import logging
+import os
+import shutil
+from typing import Any, Awaitable, Callable, Dict, List, Optional, Protocol, Sequence, Tuple
+
+from ..service_registry import ServiceRegistry
+from ..settings_manager import get_settings_manager
+from ...utils.constants import PREVIEW_EXTENSIONS
+from ...utils.file_utils import find_preview_file, get_preview_extension
+from ...utils.metadata_manager import MetadataManager
+from ...utils.sidecar_paths import (
+    METADATA_SUFFIX,
+    STORAGE_MODE_CENTRALIZED,
+    get_configured_sidecar_root,
+    get_sidecar_root,
+    get_storage_mode,
+    resolve_centralized_dir_for_dir,
+)
+
+
+class SidecarMigrationProgressReporter(Protocol):
+    """Protocol for progress reporters used during sidecar migration."""
+
+    async def on_progress(self, payload: Dict[str, Any]) -> None:
+        """Handle a sidecar migration progress update."""
+
+
+ScannerFactory = Callable[[], Awaitable[Any]]
+
+DIRECTION_TO_CENTRALIZED = "to_centralized"
+DIRECTION_TO_ALONGSIDE = "to_alongside"
+DIRECTION_RELOCATE_ROOT = "relocate_root"
+
+# Same candidate set find_preview_file recognizes: every PREVIEW_EXTENSIONS
+# suffix plus the legacy ".example.0.jpeg" (issue #225).
+_PREVIEW_CANDIDATE_EXTENSIONS = tuple(PREVIEW_EXTENSIONS) + (".example.0.jpeg",)
+
+
+def _enumerate_preview_names(directory: str, stem: str) -> List[str]:
+    """Return preview filenames for ``stem`` present in ``directory``.
+
+    Case-insensitive full-name match against the preview candidate set, so
+    files like ``model.WEBP`` or ``model.Png`` placed by external tools are
+    migrated along with the exact-case variants.
+    """
+
+    targets = {f"{stem.lower()}{ext}" for ext in _PREVIEW_CANDIDATE_EXTENSIONS}
+    try:
+        entries = os.listdir(directory)
+    except OSError:
+        return []
+    return [entry for entry in entries if entry.lower() in targets]
+
+
+class SidecarMigrationUseCase:
+    """Move sidecars and previews between alongside and centralized layouts."""
+
+    def __init__(
+        self,
+        *,
+        scanner_factories: Sequence[Tuple[str, ScannerFactory]] | None = None,
+        settings_service=None,
+        logger: Optional[logging.Logger] = None,
+    ) -> None:
+        self._settings = settings_service or get_settings_manager()
+        self._scanner_factories: Tuple[Tuple[str, ScannerFactory], ...] = tuple(
+            scanner_factories
+            or (
+                ("lora", ServiceRegistry.get_lora_scanner),
+                ("checkpoint", ServiceRegistry.get_checkpoint_scanner),
+                ("embedding", ServiceRegistry.get_embedding_scanner),
+                ("other", ServiceRegistry.get_other_scanner),
+            )
+        )
+        self._logger = logger or logging.getLogger(__name__)
+
+    async def migrate_to_centralized(
+        self,
+        progress_cb: Optional[SidecarMigrationProgressReporter] = None,
+        *,
+        force: bool = False,
+    ) -> Dict[str, Any]:
+        """Move sidecars/previews from alongside the models into the mirror root."""
+
+        if (
+            not force
+            and get_storage_mode() == STORAGE_MODE_CENTRALIZED
+            and get_sidecar_root()
+        ):
+            return self._refusal(
+                DIRECTION_TO_CENTRALIZED,
+                "sidecar storage is already centralized; pass force=true to migrate anyway",
+            )
+        return await self._migrate(
+            direction=DIRECTION_TO_CENTRALIZED,
+            to_centralized=True,
+            progress_cb=progress_cb,
+        )
+
+    async def migrate_to_alongside(
+        self,
+        progress_cb: Optional[SidecarMigrationProgressReporter] = None,
+        *,
+        force: bool = False,
+    ) -> Dict[str, Any]:
+        """Move sidecars/previews from the mirror root back next to the models."""
+
+        if not force and get_storage_mode() != STORAGE_MODE_CENTRALIZED:
+            return self._refusal(
+                DIRECTION_TO_ALONGSIDE,
+                "sidecar storage is already alongside; pass force=true to migrate anyway",
+            )
+        return await self._migrate(
+            direction=DIRECTION_TO_ALONGSIDE,
+            to_centralized=False,
+            progress_cb=progress_cb,
+        )
+
+    async def migrate_root(
+        self,
+        old_root: str,
+        progress_cb: Optional[SidecarMigrationProgressReporter] = None,
+        *,
+        force: bool = False,
+    ) -> Dict[str, Any]:
+        """Relocate the whole mirror tree from a previous root to the configured one.
+
+        Used after ``sidecar_storage_path`` changes while centralized storage
+        is active: without it, every asset under the old root would silently
+        disappear from the application. Moves every file keeping the
+        root-relative structure, rewrites the ``preview_url`` prefix inside
+        moved sidecars, reconciles scanner caches, and prunes the emptied old
+        tree. Keep-newer conflict resolution matches :meth:`_transfer`.
+        """
+
+        if not force and get_storage_mode() != STORAGE_MODE_CENTRALIZED:
+            return self._refusal(
+                DIRECTION_RELOCATE_ROOT,
+                "sidecar storage is not centralized; pass force=true to relocate anyway",
+            )
+        new_root = get_configured_sidecar_root()
+        if not new_root:
+            return self._refusal(
+                DIRECTION_RELOCATE_ROOT,
+                "cannot resolve the centralized sidecar root",
+            )
+        old = (
+            os.path.abspath(os.path.expanduser(old_root.strip()))
+            if isinstance(old_root, str) and old_root.strip()
+            else ""
+        )
+        if not old:
+            return self._refusal(DIRECTION_RELOCATE_ROOT, "old_root is required")
+        if os.path.normpath(old) == os.path.normpath(new_root):
+            return self._refusal(
+                DIRECTION_RELOCATE_ROOT,
+                "old_root matches the configured sidecar root",
+            )
+
+        files: List[Tuple[str, str]] = []
+        if os.path.isdir(old):
+            for dirpath, _dirnames, filenames in os.walk(old):
+                rel = os.path.relpath(dirpath, old)
+                target_dir = new_root if rel == os.curdir else os.path.join(new_root, rel)
+                for filename in filenames:
+                    files.append(
+                        (os.path.join(dirpath, filename), os.path.join(target_dir, filename))
+                    )
+
+        errors: List[Dict[str, str]] = []
+        counters: Dict[str, Any] = {"moved": 0, "conflicts": 0}
+        moved_sidecars: List[str] = []
+
+        async def emit(status: str, **extra: Any) -> None:
+            if progress_cb is None:
+                return
+            payload: Dict[str, Any] = {
+                "type": "sidecar_migration_progress",
+                "status": status,
+                "direction": DIRECTION_RELOCATE_ROOT,
+                "total": len(files),
+                "processed": extra.pop("processed", 0),
+                "moved": counters["moved"],
+                "skipped": 0,
+                "conflicts": counters["conflicts"],
+                "errors": len(errors),
+            }
+            payload.update(extra)
+            await progress_cb.on_progress(payload)
+
+        await emit("started")
+
+        for index, (src, dst) in enumerate(files, start=1):
+            try:
+                if self._transfer(src, dst, counters) and src.endswith(METADATA_SUFFIX):
+                    moved_sidecars.append(dst)
+            except Exception as exc:
+                self._logger.error(
+                    "Sidecar root relocation failed for %s: %s", src, exc, exc_info=True
+                )
+                errors.append({"model": os.path.basename(src), "error": str(exc)})
+            await emit("processing", processed=index, current=os.path.basename(src))
+
+        old_prefix = old.replace(os.sep, "/").rstrip("/") + "/"
+        new_prefix = new_root.replace(os.sep, "/").rstrip("/") + "/"
+        for sidecar in moved_sidecars:
+            self._rewrite_root_prefix(sidecar, old_prefix, new_prefix)
+        await self._reconcile_root_prefix(old_prefix, new_prefix)
+
+        # Prune the emptied old tree, best-effort.
+        if os.path.isdir(old):
+            for dirpath, dirnames, filenames in os.walk(old, topdown=False):
+                if filenames:
+                    continue
+                for dirname in dirnames:
+                    try:
+                        os.rmdir(os.path.join(dirpath, dirname))
+                    except OSError:
+                        pass
+                try:
+                    os.rmdir(dirpath)
+                except OSError:
+                    pass
+
+        await emit("completed")
+
+        return {
+            "success": not errors,
+            "direction": DIRECTION_RELOCATE_ROOT,
+            "models_total": len(files),
+            "models_processed": len(files),
+            "models_moved": 0,
+            "moved": counters["moved"],
+            "skipped": 0,
+            "conflicts": counters["conflicts"],
+            "errors": errors,
+            "error_count": len(errors),
+        }
+
+    def _rewrite_root_prefix(
+        self, sidecar_path: str, old_prefix: str, new_prefix: str
+    ) -> None:
+        """Repoint preview_url inside a relocated sidecar from old to new root."""
+
+        try:
+            with open(sidecar_path, "r", encoding="utf-8") as handle:
+                metadata = json.load(handle)
+        except (OSError, json.JSONDecodeError) as exc:
+            self._logger.warning(
+                "Sidecar root relocation: cannot read %s: %s", sidecar_path, exc
+            )
+            return
+
+        preview_url = metadata.get("preview_url")
+        if not isinstance(preview_url, str) or not preview_url.startswith(old_prefix):
+            return
+        metadata["preview_url"] = new_prefix + preview_url[len(old_prefix):]
+        try:
+            with open(sidecar_path, "w", encoding="utf-8") as handle:
+                json.dump(metadata, handle, ensure_ascii=False, indent=2)
+        except OSError as exc:
+            self._logger.warning(
+                "Sidecar root relocation: cannot rewrite %s: %s", sidecar_path, exc
+            )
+
+    async def _reconcile_root_prefix(self, old_prefix: str, new_prefix: str) -> None:
+        """Rewrite old-root preview URLs in every scanner cache after relocation."""
+
+        for model_type, factory in self._active_scanner_factories():
+            try:
+                scanner = await factory()
+                cache = await scanner.get_cached_data()
+                changed = False
+                for item in cache.raw_data:
+                    preview_url = item.get("preview_url")
+                    if (
+                        isinstance(preview_url, str)
+                        and preview_url.startswith(old_prefix)
+                    ):
+                        item["preview_url"] = new_prefix + preview_url[len(old_prefix):]
+                        changed = True
+                if changed and hasattr(scanner, "_persist_current_cache"):
+                    await scanner._persist_current_cache()
+            except Exception as exc:
+                self._logger.error(
+                    "Sidecar root relocation: failed to reconcile %s cache: %s",
+                    model_type,
+                    exc,
+                    exc_info=True,
+                )
+
+    @staticmethod
+    def _refusal(direction: str, message: str) -> Dict[str, Any]:
+        return {
+            "success": False,
+            "error": message,
+            "direction": direction,
+            "models_total": 0,
+            "models_processed": 0,
+            "models_moved": 0,
+            "moved": 0,
+            "skipped": 0,
+            "conflicts": 0,
+            "errors": [],
+            "error_count": 0,
+        }
+
+    def _active_scanner_factories(self) -> Tuple[Tuple[str, ScannerFactory], ...]:
+        """Drop the opt-in other scanner while Other Models is disabled."""
+
+        if self._settings.is_other_models_enabled():
+            return self._scanner_factories
+        return tuple(entry for entry in self._scanner_factories if entry[0] != "other")
+
+    async def _collect_model_paths(
+        self, errors: List[Dict[str, str]]
+    ) -> List[Tuple[Any, List[str]]]:
+        """Enumerate model file paths grouped by the scanner that owns them."""
+
+        groups: List[Tuple[Any, List[str]]] = []
+        for model_type, factory in self._active_scanner_factories():
+            try:
+                scanner = await factory()
+                cache = await scanner.get_cached_data()
+            except Exception as exc:
+                self._logger.error(
+                    "Sidecar migration: failed to enumerate %s models: %s",
+                    model_type,
+                    exc,
+                )
+                errors.append({"model": model_type, "error": f"enumeration failed: {exc}"})
+                continue
+            paths = [
+                entry["file_path"]
+                for entry in cache.raw_data
+                if entry.get("file_path")
+            ]
+            groups.append((scanner, paths))
+        return groups
+
+    @staticmethod
+    def _move_file(src: str, dst: str) -> None:
+        """Move a file, tolerating EXDEV when the layouts span filesystems."""
+
+        os.makedirs(os.path.dirname(dst), exist_ok=True)
+        try:
+            os.rename(src, dst)
+        except OSError as exc:
+            if exc.errno != errno.EXDEV:
+                raise
+            shutil.copy2(src, dst)
+            os.remove(src)
+
+    async def _migrate(
+        self,
+        *,
+        direction: str,
+        to_centralized: bool,
+        progress_cb: Optional[SidecarMigrationProgressReporter],
+    ) -> Dict[str, Any]:
+        root = get_configured_sidecar_root()
+        if not root:
+            return self._refusal(
+                direction,
+                "cannot resolve the centralized sidecar root",
+            )
+
+        errors: List[Dict[str, str]] = []
+        scanner_groups = await self._collect_model_paths(errors)
+
+        total = sum(len(paths) for _, paths in scanner_groups)
+        processed = 0
+        models_moved = 0
+        moved = 0
+        skipped = 0
+        conflicts = 0
+        # (file_path, final preview path at the destination layout), grouped
+        # by scanner so caches can be reconciled after the move.
+        preview_updates: List[Tuple[Any, List[Tuple[str, str]]]] = []
+
+        async def emit(status: str, **extra: Any) -> None:
+            if progress_cb is None:
+                return
+            payload: Dict[str, Any] = {
+                "type": "sidecar_migration_progress",
+                "status": status,
+                "direction": direction,
+                "total": total,
+                "processed": processed,
+                "moved": moved,
+                "skipped": skipped,
+                "conflicts": conflicts,
+                "errors": len(errors),
+            }
+            payload.update(extra)
+            await progress_cb.on_progress(payload)
+
+        await emit("started")
+
+        for scanner, model_paths in scanner_groups:
+            updates: List[Tuple[str, str]] = []
+            for model_path in model_paths:
+                processed += 1
+                current = os.path.basename(model_path)
+                try:
+                    result = await self._migrate_model(
+                        model_path,
+                        root=root,
+                        to_centralized=to_centralized,
+                    )
+                    moved += result["moved"]
+                    conflicts += result["conflicts"]
+                    if result["skipped"]:
+                        skipped += 1
+                    else:
+                        updates.append((model_path, result["preview_url"]))
+                    if result["moved"]:
+                        models_moved += 1
+                except Exception as exc:
+                    self._logger.error(
+                        "Sidecar migration failed for %s: %s", model_path, exc, exc_info=True
+                    )
+                    errors.append({"model": current, "error": str(exc)})
+                await emit("processing", current=current)
+            preview_updates.append((scanner, updates))
+
+        await self._reconcile_scanner_caches(preview_updates)
+
+        await emit("completed")
+
+        return {
+            "success": not errors,
+            "direction": direction,
+            "models_total": total,
+            "models_processed": processed,
+            "models_moved": models_moved,
+            "moved": moved,
+            "skipped": skipped,
+            "conflicts": conflicts,
+            "errors": errors,
+            "error_count": len(errors),
+        }
+
+    async def _migrate_model(
+        self,
+        model_path: str,
+        *,
+        root: str,
+        to_centralized: bool,
+    ) -> Dict[str, Any]:
+        """Migrate one model's sidecar + previews; return per-model counters.
+
+        ``preview_url`` in the result is the model's final preview path in the
+        destination layout ("" when none), used to reconcile scanner caches.
+        """
+
+        result: Dict[str, Any] = {"moved": 0, "conflicts": 0, "skipped": 0, "preview_url": ""}
+
+        model_path = os.path.abspath(model_path)
+        if not os.path.exists(model_path):
+            self._logger.warning(
+                "Sidecar migration: model file missing, skipping: %s", model_path
+            )
+            result["skipped"] = 1
+            return result
+
+        model_dir = os.path.dirname(model_path)
+        mirror_dir = resolve_centralized_dir_for_dir(model_dir, sidecar_root=root)
+        if mirror_dir is None:
+            self._logger.warning(
+                "Sidecar migration: %s is outside configured model roots, skipping",
+                model_path,
+            )
+            result["skipped"] = 1
+            return result
+
+        if to_centralized:
+            src_dir, dst_dir = model_dir, mirror_dir
+        else:
+            src_dir, dst_dir = mirror_dir, model_dir
+
+        if os.path.normpath(src_dir) == os.path.normpath(dst_dir):
+            result["skipped"] = 1
+            return result
+
+        stem = os.path.splitext(os.path.basename(model_path))[0]
+        sidecar_name = stem + METADATA_SUFFIX
+
+        moved_previews: List[str] = []
+        for preview_name in _enumerate_preview_names(src_dir, stem):
+            src = os.path.join(src_dir, preview_name)
+            dst = os.path.join(dst_dir, preview_name)
+            if self._transfer(src, dst, result):
+                moved_previews.append(dst)
+
+        sidecar_src = os.path.join(src_dir, sidecar_name)
+        sidecar_moved = False
+        sidecar_dst = os.path.join(dst_dir, sidecar_name)
+        if os.path.exists(sidecar_src):
+            sidecar_moved = self._transfer(sidecar_src, sidecar_dst, result)
+
+        if sidecar_moved:
+            await self._rewrite_sidecar_paths(sidecar_dst, model_path, moved_previews)
+
+        # Ground truth from the destination directory: covers conflict-keep
+        # and partial moves, not just the previews transferred in this run.
+        final_preview = find_preview_file(stem, dst_dir)
+        if final_preview:
+            result["preview_url"] = final_preview.replace(os.sep, "/")
+
+        return result
+
+    async def _reconcile_scanner_caches(
+        self, preview_updates: List[Tuple[Any, List[Tuple[str, str]]]]
+    ) -> None:
+        """Point scanner cache entries at the post-migration preview locations.
+
+        Without this the list API keeps serving pre-migration ``preview_url``
+        values whose files no longer exist; hitting one triggers the preview
+        route's stale-URL cleanup, which would wipe the reference for good.
+        A failing scanner is logged and skipped — the on-disk migration has
+        already succeeded, and a full rescan repairs the cache.
+        """
+
+        for scanner, updates in preview_updates:
+            if not updates:
+                continue
+            try:
+                cache = await scanner.get_cached_data()
+                changed = False
+                for file_path, preview_url in updates:
+                    entry = next(
+                        (item for item in cache.raw_data if item.get("file_path") == file_path),
+                        None,
+                    )
+                    if entry is None:
+                        continue
+                    if entry.get("preview_url", "") == preview_url:
+                        continue
+                    if hasattr(cache, "update_preview_url"):
+                        await cache.update_preview_url(
+                            file_path,
+                            preview_url,
+                            entry.get("preview_nsfw_level", 0),
+                        )
+                    else:  # pragma: no cover - minimal cache doubles
+                        entry["preview_url"] = preview_url
+                    changed = True
+                if changed and hasattr(scanner, "_persist_current_cache"):
+                    await scanner._persist_current_cache()
+            except Exception as exc:
+                self._logger.error(
+                    "Sidecar migration: failed to reconcile scanner cache: %s",
+                    exc,
+                    exc_info=True,
+                )
+
+    def _transfer(self, src: str, dst: str, result: Dict[str, Any]) -> bool:
+        """Move ``src`` to ``dst`` with keep-newer conflict resolution.
+
+        Returns True when the file was actually moved to the destination. On a
+        conflict the newer file wins: a newer source replaces the destination;
+        a newer (or equal) destination is kept and the source is deleted.
+        """
+
+        if os.path.exists(dst):
+            result["conflicts"] += 1
+            if os.path.getmtime(src) > os.path.getmtime(dst):
+                self._logger.info(
+                    "Sidecar migration: conflict at %s; source is newer, replacing", dst
+                )
+                os.remove(dst)
+            else:
+                self._logger.info(
+                    "Sidecar migration: conflict at %s; destination is newer, keeping it",
+                    dst,
+                )
+                os.remove(src)
+                return False
+        self._move_file(src, dst)
+        result["moved"] += 1
+        return True
+
+    async def _rewrite_sidecar_paths(
+        self,
+        sidecar_path: str,
+        model_path: str,
+        moved_previews: List[str],
+    ) -> None:
+        """Update path fields inside a moved sidecar, mirroring ModelScanner."""
+
+        with open(sidecar_path, "r", encoding="utf-8") as handle:
+            metadata = json.load(handle)
+
+        stem = os.path.splitext(os.path.basename(model_path))[0]
+        metadata["file_path"] = model_path.replace(os.sep, "/")
+        metadata["file_name"] = stem
+
+        if moved_previews and metadata.get("preview_url"):
+            recorded_ext = get_preview_extension(metadata["preview_url"])
+            chosen = next(
+                (
+                    path
+                    for path in moved_previews
+                    if get_preview_extension(path) == recorded_ext
+                ),
+                moved_previews[0],
+            )
+            metadata["preview_url"] = chosen.replace(os.sep, "/")
+
+        await MetadataManager.save_metadata(sidecar_path, metadata)
+
+    async def execute_with_error_handling(
+        self,
+        *,
+        direction: str,
+        progress_cb: Optional[SidecarMigrationProgressReporter] = None,
+        force: bool = False,
+        old_root: Optional[str] = None,
+    ) -> Dict[str, Any]:
+        """Wrapper providing progress notification on unexpected failures."""
+
+        try:
+            if direction == DIRECTION_TO_CENTRALIZED:
+                return await self.migrate_to_centralized(progress_cb, force=force)
+            if direction == DIRECTION_TO_ALONGSIDE:
+                return await self.migrate_to_alongside(progress_cb, force=force)
+            if direction == DIRECTION_RELOCATE_ROOT:
+                return await self.migrate_root(old_root or "", progress_cb, force=force)
+            raise ValueError(
+                f"direction must be {DIRECTION_TO_CENTRALIZED!r}, "
+                f"{DIRECTION_TO_ALONGSIDE!r} or {DIRECTION_RELOCATE_ROOT!r}"
+            )
+        except Exception as exc:
+            if progress_cb is not None:
+                await progress_cb.on_progress(
+                    {
+                        "type": "sidecar_migration_progress",
+                        "status": "error",
+                        "direction": direction,
+                        "error": str(exc),
+                    }
+                )
+            raise

py/utils/metadata_manager.py

@@ -8,6 +8,7 @@ from typing import Any, Dict, Optional, Type, Union, cast
 from .models import BaseModelMetadata, CheckpointMetadata, EmbeddingMetadata, LoraMetadata
 from .file_utils import normalize_path, find_preview_file, calculate_sha256, calculate_autov3
 from .lora_metadata import extract_lora_metadata, extract_checkpoint_metadata
+from .sidecar_paths import get_metadata_path, get_preview_dir, resolve_metadata_path
 
 logger = logging.getLogger(__name__)
 
@@ -32,7 +33,7 @@ class MetadataManager:
             - metadata: BaseModelMetadata instance or None
             - should_skip: True if corrupted metadata file exists and model should be skipped
         """
-        metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
+        metadata_path = get_metadata_path(file_path)
         
         # Check if metadata file exists
         if not os.path.exists(metadata_path):
@@ -98,11 +99,7 @@ class MetadataManager:
                 payload.update(unknown_fields)
         else:
             if not should_skip:
-                metadata_path = (
+                metadata_path = resolve_metadata_path(file_path)
-                    file_path
-                    if file_path.endswith(".metadata.json")
-                    else f"{os.path.splitext(file_path)[0]}.metadata.json"
-                )
                 if os.path.exists(metadata_path):
                     try:
                         with open(metadata_path, "r", encoding="utf-8") as handle:
@@ -150,7 +147,7 @@ class MetadataManager:
             return model_data
 
         folder = model_data.get("folder")
-        metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
+        metadata_path = get_metadata_path(file_path)
         sidecar_exists = os.path.exists(metadata_path)
         cached = model_data.copy()
         payload = await MetadataManager.load_metadata_payload(file_path)
@@ -188,15 +185,14 @@ class MetadataManager:
           bool: Success or failure
         """
         # Determine if the input is a metadata path or a model file path
-        if path.endswith('.metadata.json'):
+        metadata_path = resolve_metadata_path(path)
-            metadata_path = path
-        else:
-            # Use existing logic for model file paths
-            file_path = path
-            metadata_path = f"{os.path.splitext(file_path)[0]}.metadata.json"
         temp_path = f"{metadata_path}.tmp"
         
         try:
+            # Centralized sidecar mirrors may not exist yet (unlike the model's
+            # own directory in alongside mode, which always does).
+            os.makedirs(os.path.dirname(metadata_path), exist_ok=True)
+
             # Convert to dict if needed
             if isinstance(metadata, BaseModelMetadata):
                 metadata_dict = metadata.to_dict()
@@ -259,10 +255,9 @@ class MetadataManager:
             
         try:
             base_name = os.path.splitext(os.path.basename(file_path))[0]
-            dir_path = os.path.dirname(file_path)
 
             # Find preview image
-            preview_url = find_preview_file(base_name, dir_path)
+            preview_url = find_preview_file(base_name, get_preview_dir(file_path))
             
             # Calculate file hash
             start_hash_time = time.perf_counter()
@@ -386,15 +381,16 @@ class MetadataManager:
         # Check if preview exists at the current location
         preview_url = metadata.preview_url
         if preview_url:
-            # Get directory parts of both paths
+            # Get directory parts of both paths; the preview directory is the
-            file_dir = os.path.dirname(file_path)
+            # sidecar/preview dir (the model's own dir in alongside mode, the
+            # centralized mirror otherwise).
+            file_dir = get_preview_dir(file_path)
             preview_dir = os.path.dirname(preview_url)
             
             # Update preview if it doesn't exist OR if model and preview are in different directories
             if not os.path.exists(preview_url) or file_dir != preview_dir:
                 base_name = os.path.splitext(os.path.basename(file_path))[0]
-                dir_path = os.path.dirname(file_path)
+                new_preview_url = find_preview_file(base_name, file_dir)
-                new_preview_url = find_preview_file(base_name, dir_path)
                 if new_preview_url:
                     metadata.preview_url = normalize_path(new_preview_url)
                     need_update = True

py/utils/sidecar_paths.py

@@ -0,0 +1,268 @@
+"""Resolution of sidecar metadata and preview storage paths.
+
+All code that needs the on-disk location of a model's ``.metadata.json``
+sidecar or preview assets MUST go through these helpers instead of deriving
+paths inline (``splitext(model_path)[0] + ".metadata.json"`` and friends).
+
+Two storage modes are supported, selected by the ``sidecar_storage_mode``
+setting:
+
+- ``alongside`` (default): sidecars and previews live next to the model
+  file, the historical layout other tools may rely on.
+- ``centralized``: sidecars and previews live under a configurable root
+  (``sidecar_storage_path`` setting, default ``<settings_dir>/sidecars``),
+  mirroring the library-relative directory structure:
+  ``<root>/<library>/<root_basename-roothash>/<rel_dir>/<name>.metadata.json``.
+
+All helpers are pure path computations: no directory scans and no file I/O
+on the hot path. Settings lookups go through ``SettingsManager.get`` (a dict
+read); config roots come from the already-initialized ``config`` singleton.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import logging
+import os
+import re
+from typing import List, Optional
+
+logger = logging.getLogger(__name__)
+
+METADATA_SUFFIX = ".metadata.json"
+
+STORAGE_MODE_ALONGSIDE = "alongside"
+STORAGE_MODE_CENTRALIZED = "centralized"
+
+_VALID_MODES = frozenset({STORAGE_MODE_ALONGSIDE, STORAGE_MODE_CENTRALIZED})
+
+
+def _get_settings_value(key: str, default=None):
+    """Read a setting defensively; never fail path resolution on settings errors."""
+
+    try:
+        from ..services.settings_manager import get_settings_manager
+
+        value = get_settings_manager().get(key)
+    except Exception as exc:  # pragma: no cover - defensive fallback
+        logger.debug("sidecar_paths: settings lookup for %r failed: %s", key, exc)
+        return default
+    return default if value is None else value
+
+
+def get_storage_mode() -> str:
+    """Return the active sidecar storage mode (``alongside`` unless configured)."""
+
+    mode = _get_settings_value("sidecar_storage_mode", STORAGE_MODE_ALONGSIDE)
+    if mode not in _VALID_MODES:
+        return STORAGE_MODE_ALONGSIDE
+    return mode
+
+
+def is_centralized() -> bool:
+    """Return True when centralized sidecar storage is active and resolvable."""
+
+    return get_storage_mode() == STORAGE_MODE_CENTRALIZED and bool(get_sidecar_root())
+
+
+def _resolve_root_from_settings() -> str:
+    """Resolve the configured/default centralized root, ignoring the active mode."""
+
+    configured = _get_settings_value("sidecar_storage_path", "")
+    if configured and isinstance(configured, str):
+        root = os.path.abspath(os.path.expanduser(configured.strip()))
+        if root:
+            return root
+
+    # Default: <settings_dir>/sidecars
+    try:
+        from .settings_paths import get_settings_dir
+
+        return os.path.join(get_settings_dir(), "sidecars")
+    except Exception as exc:  # pragma: no cover - defensive fallback
+        logger.warning("sidecar_paths: cannot resolve default sidecar root: %s", exc)
+        return ""
+
+
+def get_sidecar_root() -> str:
+    """Return the absolute root directory for centralized sidecar storage.
+
+    Empty string when centralized storage is not usable (mode alongside or an
+    unresolvable configured path).
+    """
+
+    if get_storage_mode() != STORAGE_MODE_CENTRALIZED:
+        return ""
+
+    return _resolve_root_from_settings()
+
+
+def get_configured_sidecar_root() -> str:
+    """Return the centralized sidecar root regardless of the active mode.
+
+    Unlike :func:`get_sidecar_root`, this resolves the configured
+    ``sidecar_storage_path`` (or the ``<settings_dir>/sidecars`` default) even
+    when the storage mode is ``alongside``. Migration tooling needs both
+    layouts at once and must not depend on which mode is currently active.
+    """
+
+    return _resolve_root_from_settings()
+
+
+def sanitize_path_component(name: str) -> str:
+    """Return a filesystem-safe single path component."""
+
+    safe = re.sub(r"[^A-Za-z0-9_.-]", "_", name or "")
+    return safe or "_"
+
+
+def _iter_model_roots() -> List[str]:
+    """Return every configured model root for the active library."""
+
+    try:
+        from ..config import config
+    except Exception as exc:  # pragma: no cover - defensive fallback
+        logger.debug("sidecar_paths: config unavailable: %s", exc)
+        return []
+
+    roots: List[str] = []
+    for attr in (
+        "loras_roots",
+        "base_models_roots",
+        "embeddings_roots",
+        "other_roots",
+        "extra_loras_roots",
+        "extra_checkpoints_roots",
+        "extra_unet_roots",
+        "extra_embeddings_roots",
+    ):
+        value = getattr(config, attr, None)
+        if value:
+            roots.extend(value)
+    return roots
+
+
+def _normalize_for_match(path: str) -> str:
+    return os.path.normpath(os.path.abspath(path))
+
+
+def root_mirror_component(root_path: str) -> str:
+    """Return the mirror path component identifying a model root.
+
+    ``<sanitized basename>-<hash>`` where the hash is a short digest of the
+    normalized absolute root path. Two roots sharing a basename (e.g.
+    ``/mnt/a/loras`` and ``/mnt/b/loras``) would otherwise map to the same
+    mirror directory and overwrite each other's sidecars.
+    """
+
+    normalized = _normalize_for_match(root_path)
+    digest = hashlib.sha256(normalized.encode("utf-8")).hexdigest()[:8]
+    return f"{sanitize_path_component(os.path.basename(normalized))}-{digest}"
+
+
+def resolve_centralized_dir(model_path: str) -> Optional[str]:
+    """Return the centralized mirror directory for ``model_path``.
+
+    The mirror layout is
+    ``<sidecar_root>/<library>/<root_basename-roothash>/<rel_dir>``
+    where ``rel_dir`` is the model's directory relative to the model root that
+    contains it. The longest matching root wins so nested roots resolve to the
+    most specific mirror. Returns ``None`` when centralized storage is inactive
+    or the path is not under any configured model root.
+    """
+
+    return resolve_centralized_dir_for_dir(
+        os.path.dirname(_normalize_for_match(model_path))
+    )
+
+
+def resolve_centralized_dir_for_dir(
+    model_dir: str, *, sidecar_root: Optional[str] = None
+) -> Optional[str]:
+    """Return the centralized mirror directory for a model *directory*.
+
+    Same layout as :func:`resolve_centralized_dir`, but accepts the directory
+    itself. Used by folder-level operations (folder rename, mirror-tree walks)
+    that have no model file path to derive from. Passing a configured model
+    root returns the mirror base for that root.
+
+    ``sidecar_root`` overrides the root lookup; pass
+    :func:`get_configured_sidecar_root` to resolve mirror paths independently
+    of the active storage mode (migration tooling).
+    """
+
+    root = sidecar_root if sidecar_root is not None else get_sidecar_root()
+    if not root:
+        return None
+
+    normalized_dir = _normalize_for_match(model_dir)
+
+    best_root: Optional[str] = None
+    for candidate in _iter_model_roots():
+        if not candidate:
+            continue
+        normalized = _normalize_for_match(candidate)
+        if normalized_dir == normalized or normalized_dir.startswith(normalized + os.sep):
+            if best_root is None or len(normalized) > len(best_root):
+                best_root = normalized
+
+    if best_root is None:
+        return None
+
+    try:
+        from ..services.settings_manager import get_settings_manager
+
+        library = get_settings_manager().get_active_library_name() or "default"
+    except Exception:  # pragma: no cover - defensive fallback
+        library = "default"
+
+    rel_dir = os.path.relpath(normalized_dir, best_root)
+    parts = [root, sanitize_path_component(library), root_mirror_component(best_root)]
+    if rel_dir and rel_dir != os.curdir:
+        parts.extend(sanitize_path_component(part) for part in rel_dir.split(os.sep) if part not in ("", os.curdir))
+    return os.path.join(*parts)
+
+
+def get_sidecar_dir(model_path: str) -> str:
+    """Return the directory holding the model's sidecar/preview assets.
+
+    Centralized mode falls back to the model's own directory (with a warning)
+    when the path lies outside every configured model root.
+    """
+
+    if get_storage_mode() == STORAGE_MODE_CENTRALIZED:
+        mirror = resolve_centralized_dir(model_path)
+        if mirror:
+            return mirror
+        logger.warning(
+            "sidecar_paths: %s is outside configured model roots; storing sidecar alongside",
+            model_path,
+        )
+    return os.path.dirname(os.path.abspath(model_path))
+
+
+def get_metadata_path(model_path: str) -> str:
+    """Return the ``.metadata.json`` sidecar path for a model file."""
+
+    base_name = os.path.splitext(os.path.basename(model_path))[0] + METADATA_SUFFIX
+    return os.path.join(get_sidecar_dir(model_path), base_name)
+
+
+def is_metadata_path(path: str) -> bool:
+    """Return True when ``path`` already points at a metadata sidecar file."""
+
+    return path.endswith(METADATA_SUFFIX)
+
+
+def resolve_metadata_path(path: str) -> str:
+    """Accept either a model path or a sidecar path and return the sidecar path."""
+
+    if is_metadata_path(path):
+        return path
+    return get_metadata_path(path)
+
+
+def get_preview_dir(model_path: str) -> str:
+    """Return the directory holding the model's preview assets."""
+
+    return get_sidecar_dir(model_path)

static/css/components/modal/delete-modal.css

@@ -42,6 +42,18 @@
     animation: modalFadeIn 0.2s ease-out;
 }
 
+/* The folder delete confirm button is held disabled while the folder contents
+   are checked against the backend, so it must not look clickable. */
+#deleteFolderModal .delete-btn:disabled {
+    opacity: 0.5;
+    cursor: not-allowed;
+    transform: none;
+}
+
+#deleteFolderModal .delete-btn:disabled:hover {
+    background: var(--lora-error);
+}
+
 #resolveFilenameConflictsModal .confirmation-message {
     color: var(--text-color);
     margin: var(--space-2) 0;

static/js/components/SidebarManager.js

@@ -52,6 +52,9 @@ export class SidebarManager {
         this._renameFolderNode = null;
         this._pendingDeleteFolderPath = null;
         this._deleteFolderModalWired = false;
+        // Bumped on every modal open/close so a late dry-run answer can never
+        // repaint a modal the user has already dismissed or retargeted.
+        this._deleteFolderProbeToken = 0;
 
         // Bind methods
         this.handleTreeClick = this.handleTreeClick.bind(this);
@@ -982,42 +985,71 @@ export class SidebarManager {
     /**
      * Open the folder delete modal for *path*.
      *
-     * The tree already knows whether the subtree holds models (the same
+     * The models-only set that dims empty nodes is only a prediction: it is
-     * models-only set that dims empty nodes), so the modal opens in one of two
+     * built from the scanned, non-excluded models, while the delete guard walks
-     * states without a round trip: a confirmation for a model-free folder, or
+     * the folder on disk and refuses on any weight file — excluded ones
-     * an explanation when models would have to be cascaded over — a
+     * included. So the modal opens on the prediction for an instant answer and
-     * folder-level cascade would bypass the per-model lifecycle bookkeeping,
+     * is then corrected by a dry run of the very delete the user is about to
-     * so the backend refuses it and the UI says why.
+     * confirm, which is the only way the button can never contradict the
+     * backend (see `_verifyFolderContents`).
      */
-    showDeleteFolderModal(path) {
+    async showDeleteFolderModal(path) {
         const modal = document.getElementById('deleteFolderModal');
         if (!modal) return;
 
         // Defensive: the modal may have been absent when listeners were wired.
         this._wireDeleteFolderModal();
 
+        // Opening the modal — or targeting another folder — retires any
+        // in-flight check from a previous open.
+        const token = ++this._deleteFolderProbeToken;
+
+        const holdsModels = this.nonEmptyFolders ? this.nonEmptyFolders.has(path) : false;
+        const prediction = holdsModels
+            ? {
+                state: 'blocked',
+                messageKey: 'sidebar.deleteFolderModal.notEmptyMessage',
+                messageFallback: 'This folder still contains models. Delete or move them first.',
+            }
+            : { state: 'confirm' };
+
+        const probePending = this._supportsFolderManagement()
+            && typeof this.apiClient.deleteFolder === 'function';
+
+        this._renderDeleteFolderModal(path, prediction.state, {
+            ...prediction,
+            checking: probePending,
+        });
+
+        modalManager.showModal('deleteFolderModal');
+
+        if (!probePending) return;
+
+        await this._verifyFolderContents(path, token, prediction);
+    }
+
+    /**
+     * Paint one state of the folder delete modal.
+     *
+     * `state` is 'confirm' (deletion may proceed), 'blocked' (models would be
+     * cascaded over, which the backend refuses) or 'busy' (a staged delete is
+     * still pending inside the folder). `checking` keeps the confirm button
+     * disabled while the authoritative server-side check runs.
+     */
+    _renderDeleteFolderModal(path, state, options = {}) {
+        const modal = document.getElementById('deleteFolderModal');
+        if (!modal) return;
+
         const title = modal.querySelector('[data-role="title"]');
         const message = modal.querySelector('[data-role="message"]');
         const info = modal.querySelector('[data-role="info"]');
         const confirmBtn = modal.querySelector('[data-action="confirm-delete-folder"]');
-
+        const checking = Boolean(options.checking);
-        const holdsModels = this.nonEmptyFolders ? this.nonEmptyFolders.has(path) : false;
 
         const pathLine = `<strong>${escapeHtml(translate('sidebar.deleteFolderModal.folderLabel', {}, 'Folder'))}:</strong> ${escapeHtml(path)}`;
+        const extraLines = [];
 
-        if (holdsModels) {
+        if (state === 'confirm') {
-            this._pendingDeleteFolderPath = null;
-            title.textContent = translate(
-                'sidebar.deleteFolderModal.notEmptyTitle', {}, 'Folder is not empty'
-            );
-            message.textContent = translate(
-                'sidebar.deleteFolderModal.notEmptyMessage', {},
-                'This folder still contains models. Delete or move them first.'
-            );
-            info.innerHTML = pathLine;
-            confirmBtn.style.display = 'none';
-            modal.dataset.state = 'blocked';
-        } else {
             this._pendingDeleteFolderPath = path;
             title.textContent = translate(
                 'sidebar.deleteFolderModal.title', {}, 'Delete folder?'
@@ -1026,18 +1058,146 @@ export class SidebarManager {
                 'sidebar.deleteFolderModal.message', {},
                 'The folder and everything inside it will be permanently removed from disk.'
             );
-            info.innerHTML = `${pathLine}<br>${escapeHtml(translate(
+            if (!checking) {
+                // While the check runs the "no models" claim is still only the
+                // sidebar's prediction, so it is not repeated as a fact.
+                extraLines.push(escapeHtml(translate(
                     'sidebar.deleteFolderModal.emptyNote', {}, 'This folder contains no models.'
-            ))}`;
+                )));
+            }
             confirmBtn.style.display = '';
-            modal.dataset.state = 'confirm';
+            confirmBtn.disabled = checking;
+        } else {
+            this._pendingDeleteFolderPath = null;
+            if (state === 'busy') {
+                title.textContent = translate(
+                    'sidebar.deleteFolderModal.busyTitle', {}, 'A deletion is still pending'
+                );
+                message.textContent = translate(
+                    'sidebar.deleteFolderResult.busy', {},
+                    'A deletion is still pending inside this folder. Wait for the undo window to expire.'
+                );
+            } else {
+                title.textContent = translate(
+                    'sidebar.deleteFolderModal.notEmptyTitle', {}, 'Folder is not empty'
+                );
+                message.textContent = translate(
+                    options.messageKey || 'sidebar.deleteFolderModal.notEmptyMessage',
+                    options.messageParams || {},
+                    options.messageFallback
+                        || 'This folder still contains models. Delete or move them first.'
+                );
+            }
+            confirmBtn.style.display = 'none';
+            confirmBtn.disabled = true;
         }
 
-        modalManager.showModal('deleteFolderModal');
+        if (checking) {
+            extraLines.push(escapeHtml(translate(
+                'sidebar.deleteFolderModal.checking', {}, 'Checking the folder contents...'
+            )));
+        }
+
+        info.innerHTML = [pathLine, ...extraLines].join('<br>');
+        modal.dataset.state = state;
+    }
+
+    /**
+     * Ask the backend what deleting *relativePath* would actually remove.
+     *
+     * The dry run is authoritative: it walks the folder on disk and applies the
+     * same guard the real delete uses, so it catches everything the sidebar
+     * prediction cannot know — excluded models, weight files no scanner indexes
+     * (a lora folder holding only a `.gguf`, say) and files added after the
+     * last scan. A check that fails for any other reason falls back to the
+     * prediction, leaving the real delete to report its own error.
+     */
+    async _verifyFolderContents(relativePath, token, prediction) {
+        let resolved = null;
+        try {
+            resolved = await this._resolveFolderAbsolutePath(relativePath);
+        } catch (error) {
+            console.error('[SidebarManager] Failed to resolve the folder path:', error);
+        }
+
+        if (token !== this._deleteFolderProbeToken) return;
+
+        if (!resolved) {
+            this._renderDeleteFolderModal(relativePath, prediction.state, prediction);
+            return;
+        }
+
+        try {
+            await this.apiClient.deleteFolder(resolved.absolutePath, { dryRun: true });
+            if (token !== this._deleteFolderProbeToken) return;
+            this._renderDeleteFolderModal(relativePath, 'confirm');
+        } catch (error) {
+            if (token !== this._deleteFolderProbeToken) return;
+            if (error?.code === 'not_empty') {
+                this._renderDeleteFolderModal(
+                    relativePath, 'blocked', this._notEmptyBlocker(error?.manifest)
+                );
+            } else if (error?.code === 'busy') {
+                this._renderDeleteFolderModal(relativePath, 'busy');
+            } else {
+                this._renderDeleteFolderModal(relativePath, prediction.state, prediction);
+            }
+        }
+    }
+
+    /**
+     * Message for a refused delete, split by whether the blocking models are
+     * excluded from the library — the case where the sidebar legitimately shows
+     * the folder as empty, which is exactly what used to be unexplained.
+     */
+    _notEmptyBlocker(manifest) {
+        const modelCount = Number(manifest?.model_count) || 0;
+        const excludedCount = Number(manifest?.excluded_model_count) || 0;
+
+        if (modelCount > 0 && excludedCount > 0) {
+            return {
+                messageKey: 'sidebar.deleteFolderModal.notEmptyMessageExcluded',
+                messageParams: { count: modelCount, excluded: excludedCount },
+                messageFallback: `This folder still contains ${modelCount} model file(s), `
+                    + `${excludedCount} of them excluded from the library. Un-exclude and `
+                    + 'delete them first — deleting a folder never cascades over model files.',
+            };
+        }
+        if (modelCount > 0) {
+            return {
+                messageKey: 'sidebar.deleteFolderModal.notEmptyMessageCount',
+                messageParams: { count: modelCount },
+                messageFallback: `This folder still contains ${modelCount} model file(s). `
+                    + 'Delete or move them first — deleting a folder never cascades over model files.',
+            };
+        }
+        return {
+            messageKey: 'sidebar.deleteFolderModal.notEmptyMessage',
+            messageFallback: 'This folder still contains models. Delete or move them first.',
+        };
+    }
+
+    /**
+     * Resolve a tree-relative folder path to the absolute business path the
+     * folder APIs expect, or null when no model root is configured.
+     */
+    async _resolveFolderAbsolutePath(relativePath) {
+        const rootsData = await this.apiClient.fetchModelRoots();
+        const roots = rootsData?.roots || [];
+        const root = this._resolveDefaultRoot(roots);
+        if (!root) return null;
+
+        return {
+            root,
+            absolutePath: this.combineRootAndRelativePath(root, relativePath),
+        };
     }
 
     hideDeleteFolderModal() {
         this._pendingDeleteFolderPath = null;
+        // Retire any in-flight check so a late answer cannot repaint a modal
+        // the user already dismissed.
+        this._deleteFolderProbeToken += 1;
         modalManager.closeModal('deleteFolderModal');
     }
 
@@ -1057,16 +1217,13 @@ export class SidebarManager {
         }
 
         try {
-            const rootsData = await this.apiClient.fetchModelRoots();
+            const resolved = await this._resolveFolderAbsolutePath(relativePath);
-            const roots = rootsData?.roots || [];
+            if (!resolved) {
-            const root = this._resolveDefaultRoot(roots);
-            if (!root) {
                 showToast('sidebar.deleteFolderResult.noRoot', {}, 'error');
                 return false;
             }
 
-            const absolutePath = this.combineRootAndRelativePath(root, relativePath);
+            const result = await this.apiClient.deleteFolder(resolved.absolutePath);
-            const result = await this.apiClient.deleteFolder(absolutePath);
 
             // Drop the node (and its subtree) from the persisted expand state
             // before refreshing, otherwise stale keys accumulate forever. A
@@ -1083,7 +1240,7 @@ export class SidebarManager {
                 // the same 20s undo affordance the model delete flow uses.
                 showActionToast('sidebar.deleteFolderResult.success', { name }, 'success', {
                     actionText: translate('toast.undo.action', {}, 'Undo'),
-                    onAction: () => this._restoreDeletedFolder(absolutePath, relativePath),
+                    onAction: () => this._restoreDeletedFolder(resolved.absolutePath, relativePath),
                 });
             } else {
                 showToast(
@@ -1097,7 +1254,18 @@ export class SidebarManager {
         } catch (error) {
             console.error('[SidebarManager] Error deleting folder:', error);
             if (error?.code === 'not_empty') {
+                // The dry run normally catches this before the user can
+                // confirm; reaching here means the folder changed in between.
+                const modelCount = Number(error?.manifest?.model_count) || 0;
+                if (modelCount > 0) {
+                    showToast(
+                        'sidebar.deleteFolderResult.notEmptyWithCount',
+                        { count: modelCount },
+                        'warning'
+                    );
+                } else {
                     showToast('sidebar.deleteFolderResult.notEmpty', {}, 'warning');
+                }
             } else if (error?.code === 'busy') {
                 showToast('sidebar.deleteFolderResult.busy', {}, 'warning');
             } else {

static/js/managers/SettingsManager.js

@@ -1192,6 +1192,9 @@ export class SettingsManager {
 
         this.updateExampleImagesOpenSettingsVisibility();
 
+        // Load sidecar storage settings
+        this.loadSidecarStorageSettings();
+
         // Load download path templates
         this.loadDownloadPathTemplates();
 
@@ -1280,6 +1283,9 @@ export class SettingsManager {
         this.attachPathField('exampleImagesLocalRoot', {
             onAfterSelect: () => this.saveInputSetting('exampleImagesLocalRoot', 'example_images_local_root'),
         });
+        this.attachPathField('sidecarStoragePath', {
+            onAfterSelect: () => this.handleSidecarStoragePathChange(),
+        });
     }
 
     loadDownloadBackendSettings() {
@@ -3379,6 +3385,223 @@ export class SettingsManager {
         this.updateExampleImagesOpenSettingsVisibility();
     }
 
+    loadSidecarStorageSettings() {
+        const currentMode = state.global.settings.sidecar_storage_mode === 'centralized'
+            ? 'centralized'
+            : 'alongside';
+
+        const modeSelect = document.getElementById('sidecarStorageMode');
+        if (modeSelect) {
+            modeSelect.value = currentMode;
+        }
+        // Baseline used to detect a mode change in handleSidecarStorageModeChange
+        this._loadedSidecarStorageMode = currentMode;
+        // Baseline used to detect a root change in handleSidecarStoragePathChange
+        this._loadedSidecarStoragePath = state.global.settings.sidecar_storage_path || '';
+
+        const pathInput = document.getElementById('sidecarStoragePath');
+        if (pathInput) {
+            pathInput.value = state.global.settings.sidecar_storage_path || '';
+        }
+
+        this.updateSidecarStorageVisibility();
+    }
+
+    updateSidecarStorageVisibility() {
+        const modeSelect = document.getElementById('sidecarStorageMode');
+        const pathSetting = document.getElementById('sidecarStoragePathSetting');
+        if (!pathSetting) return;
+
+        const mode = modeSelect ? modeSelect.value : state.global.settings.sidecar_storage_mode;
+        pathSetting.style.display = mode === 'centralized' ? 'block' : 'none';
+    }
+
+    async handleSidecarStorageModeChange() {
+        const modeSelect = document.getElementById('sidecarStorageMode');
+        if (!modeSelect) return;
+
+        const previousMode = this._loadedSidecarStorageMode || 'alongside';
+
+        await this.saveSelectSetting('sidecarStorageMode', 'sidecar_storage_mode');
+        this.updateSidecarStorageVisibility();
+
+        const newMode = modeSelect.value;
+        this._loadedSidecarStorageMode = newMode;
+
+        // Existing sidecars are not moved automatically; offer to migrate them.
+        if (newMode !== previousMode) {
+            const direction = newMode === 'centralized' ? 'to_centralized' : 'to_alongside';
+            const confirmed = await this.confirmSidecarMigration(direction);
+            if (confirmed) {
+                await this.migrateSidecars(direction);
+            } else {
+                showToast('settings.sidecarStorage.migrationDeferred', {}, 'info');
+            }
+        }
+    }
+
+    // Path change while centralized storage is active: the assets under the
+    // previous root do not move by themselves, so offer a root relocation.
+    async handleSidecarStoragePathChange() {
+        const pathInput = document.getElementById('sidecarStoragePath');
+        if (!pathInput) return;
+
+        const previousPath = this._loadedSidecarStoragePath || '';
+
+        await this.saveInputSetting('sidecarStoragePath', 'sidecar_storage_path');
+
+        const newPath = pathInput.value.trim();
+        this._loadedSidecarStoragePath = newPath;
+
+        const centralized = state.global.settings.sidecar_storage_mode === 'centralized';
+        if (centralized && previousPath && previousPath !== newPath) {
+            const confirmed = await this.confirmSidecarMigration('relocate_root');
+            if (confirmed) {
+                await this.migrateSidecars('relocate_root', { old_root: previousPath });
+            } else {
+                showToast('settings.sidecarStorage.migrationDeferred', {}, 'info');
+            }
+        }
+    }
+
+    // Entry point for the "Migrate Sidecars Now" button: the direction follows
+    // the currently saved storage mode.
+    async confirmAndMigrateSidecars() {
+        const direction = state.global.settings.sidecar_storage_mode === 'centralized'
+            ? 'to_centralized'
+            : 'to_alongside';
+        const confirmed = await this.confirmSidecarMigration(direction);
+        if (confirmed) {
+            await this.migrateSidecars(direction);
+        }
+    }
+
+    confirmSidecarMigration(direction) {
+        const modalElement = document.getElementById('sidecarMigrationConfirmModal');
+        if (!modalElement) {
+            return Promise.resolve(false);
+        }
+
+        const isToCentralized = direction === 'to_centralized';
+        const isRelocate = direction === 'relocate_root';
+
+        const titleElement = modalElement.querySelector('[data-role="title"]');
+        if (titleElement) {
+            titleElement.textContent = isRelocate
+                ? translate('modals.sidecarMigrationConfirm.titleRelocateRoot', {}, 'Move sidecars to the new storage directory?')
+                : isToCentralized
+                    ? translate('modals.sidecarMigrationConfirm.titleToCentralized', {}, 'Move sidecars to centralized storage?')
+                    : translate('modals.sidecarMigrationConfirm.titleToAlongside', {}, 'Move sidecars back next to model files?');
+        }
+
+        const messageElement = modalElement.querySelector('[data-role="message"]');
+        if (messageElement) {
+            messageElement.textContent = isRelocate
+                ? translate('settings.sidecarStorage.confirmRelocateRoot', {}, 'The centralized storage directory changed, but existing sidecars and preview images are still in the previous directory. Move them to the new directory now?')
+                : isToCentralized
+                    ? translate('settings.sidecarStorage.confirmToCentralized', {}, 'The storage mode changed, but existing .metadata.json sidecars and preview images are not moved automatically. Move them into the centralized storage directory now? You can also do this later with the "Migrate Sidecars Now" button.')
+                    : translate('settings.sidecarStorage.confirmToAlongside', {}, 'The storage mode changed, but existing .metadata.json sidecars and preview images are not moved automatically. Move them back next to their model files now? You can also do this later with the "Migrate Sidecars Now" button.');
+        }
+
+        const confirmButton = modalElement.querySelector('[data-action="confirm-sidecar-migration"]');
+        const cancelButton = modalElement.querySelector('[data-action="cancel-sidecar-migration"]');
+        if (!confirmButton || !cancelButton) {
+            return Promise.resolve(false);
+        }
+
+        confirmButton.textContent = translate('modals.sidecarMigrationConfirm.confirmButton', {}, 'Migrate Now');
+
+        return new Promise((resolve) => {
+            let resolved = false;
+
+            const cleanup = () => {
+                confirmButton.removeEventListener('click', handleConfirm);
+                cancelButton.removeEventListener('click', handleCancel);
+                document.removeEventListener('keydown', handleEscape, true);
+            };
+
+            const finalize = (proceed) => {
+                if (resolved) {
+                    return;
+                }
+                resolved = true;
+                cleanup();
+                modalElement.classList.remove('show');
+                // Keep body.modal-open: the settings modal underneath is still open.
+                resolve(proceed);
+            };
+
+            const handleConfirm = (event) => {
+                event.preventDefault();
+                finalize(true);
+            };
+
+            const handleCancel = (event) => {
+                event.preventDefault();
+                finalize(false);
+            };
+
+            // Capture phase + stopPropagation so ESC never reaches the
+            // settings modal's own ESC handler underneath.
+            const handleEscape = (event) => {
+                if (event.key === 'Escape') {
+                    event.stopPropagation();
+                    finalize(false);
+                }
+            };
+
+            confirmButton.addEventListener('click', handleConfirm);
+            cancelButton.addEventListener('click', handleCancel);
+            document.addEventListener('keydown', handleEscape, true);
+
+            modalElement.classList.add('show');
+            cancelButton.focus();
+        });
+    }
+
+    async migrateSidecars(direction, extraBody = {}) {
+        const migrateBtn = document.getElementById('migrateSidecarsBtn');
+        try {
+            if (migrateBtn) {
+                migrateBtn.disabled = true;
+                migrateBtn.textContent = translate('settings.sidecarStorage.migratingButton', {}, 'Migrating...');
+            }
+
+            state.loadingManager?.showSimpleLoading(
+                translate('settings.sidecarStorage.migrating', {}, 'Migrating sidecars...')
+            );
+
+            const response = await fetch('/api/lm/sidecars/migrate', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                // The new mode/path is already saved by the time migration runs,
+                // so the backend guard requires force=true to confirm the
+                // "switch first, then migrate" flow.
+                body: JSON.stringify({ direction, force: true, ...extraBody }),
+            });
+
+            const data = await response.json();
+            if (!response.ok || data.success === false) {
+                throw new Error(data.error || 'Migration failed');
+            }
+
+            state.loadingManager?.hide();
+            showToast('settings.sidecarStorage.migrateSuccess', {}, 'success');
+
+            // Reload so cards pick up metadata/preview paths from the new location
+            resetAndReload(true);
+        } catch (error) {
+            console.error('Error migrating sidecars:', error);
+            state.loadingManager?.hide();
+            showToast('settings.sidecarStorage.migrateFailed', { message: error.message }, 'error');
+        } finally {
+            if (migrateBtn) {
+                migrateBtn.disabled = false;
+                migrateBtn.textContent = translate('settings.sidecarStorage.migrateButton', {}, 'Migrate Sidecars Now');
+            }
+        }
+    }
+
     async loadMetadataArchiveSettings() {
         try {
             // Load current settings from state

static/js/state/index.js

@@ -62,6 +62,8 @@ const DEFAULT_SETTINGS_BASE = Object.freeze({
     download_skip_base_models: [],
     backup_auto_enabled: true,
     backup_retention_count: 5,
+    sidecar_storage_mode: 'alongside',
+    sidecar_storage_path: '',
     strip_lora_on_copy: false,
     use_new_license_icons: true,
     group_by_model: false,

templates/components/modals/confirm_modals.html

@@ -96,6 +96,20 @@
     </div>
 </div>
 
+<!-- Sidecar Migration Confirmation Modal
+     Self-managed by SettingsManager (NOT registered with ModalManager): it
+     stacks above the settings modal, like the directory picker. -->
+<div id="sidecarMigrationConfirmModal" class="modal delete-modal">
+    <div class="modal-content delete-modal-content">
+        <h2 data-role="title"></h2>
+        <p class="delete-message" data-role="message"></p>
+        <div class="modal-actions">
+            <button class="cancel-btn" data-action="cancel-sidecar-migration">{{ t('common.actions.cancel') }}</button>
+            <button class="primary-btn" data-action="confirm-sidecar-migration"></button>
+        </div>
+    </div>
+</div>
+
 <!-- Sidebar Folder Delete Confirmation Modal -->
 <!-- Shared by two states: 'confirm' (model-free folder) and 'blocked' (the
      subtree still holds models, so a cascade delete is refused). -->

templates/components/modals/settings/library.html

@@ -321,4 +321,60 @@
             ('civitai_sqlite_archive', 'settings.metadataArchive.providerOrderCivitaiSqliteArchive'),
         ], 'settings.metadataArchive.providerOrderHelp') }}
     </div>
+
+    <!-- Sidecar Storage -->
+    <div class="settings-subsection">
+        {{ sm.subsection_header('settings.sections.sidecarStorage') }}
+        <div class="setting-item">
+            <div class="setting-row">
+                <div class="setting-info">
+                    <label for="sidecarStorageMode">
+                        {{ t('settings.sidecarStorage.mode') }}
+                        <i class="fas fa-info-circle info-icon" data-tooltip="{{ t('settings.sidecarStorage.modeHelp') }}"></i>
+                    </label>
+                </div>
+                <div class="setting-control select-control">
+                    <select id="sidecarStorageMode" onchange="settingsManager.handleSidecarStorageModeChange()">
+                        <option value="alongside">{{ t('settings.sidecarStorage.modeOptions.alongside') }}</option>
+                        <option value="centralized">{{ t('settings.sidecarStorage.modeOptions.centralized') }}</option>
+                    </select>
+                </div>
+            </div>
+        </div>
+
+        <div class="setting-item" id="sidecarStoragePathSetting" style="display: none;">
+            <div class="setting-row">
+                <div class="setting-info">
+                    <label for="sidecarStoragePath">
+                        {{ t('settings.sidecarStorage.path') }}
+                        <i class="fas fa-info-circle info-icon" data-tooltip="{{ t('settings.sidecarStorage.pathHelp') }}"></i>
+                    </label>
+                </div>
+                <div class="setting-control">
+                    <div class="text-input-wrapper">
+                        <input type="text" id="sidecarStoragePath"
+                               placeholder="{{ t('settings.sidecarStorage.pathPlaceholder') }}"
+                               onblur="settingsManager.handleSidecarStoragePathChange()"
+                               onkeydown="if(event.key === 'Enter') { this.blur(); }" />
+                    </div>
+                </div>
+            </div>
+        </div>
+
+        <div class="setting-item">
+            <div class="setting-row">
+                <div class="setting-info">
+                    <label>
+                        {{ t('settings.sidecarStorage.management') }}
+                        <i class="fas fa-info-circle info-icon" data-tooltip="{{ t('settings.sidecarStorage.managementHelp') }}"></i>
+                    </label>
+                </div>
+                <div class="setting-control">
+                    <button type="button" id="migrateSidecarsBtn" class="primary-btn" onclick="settingsManager.confirmAndMigrateSidecars()">
+                        {{ t('settings.sidecarStorage.migrateButton') }}
+                    </button>
+                </div>
+            </div>
+        </div>
+    </div>
 </div>

tests/frontend/components/sidebarManager.folderManagement.test.js

@@ -631,24 +631,38 @@ describe('SidebarManager folder deletion', () => {
     vi.clearAllMocks();
   });
 
-  it('opens the confirm state for a folder whose subtree holds no models', () => {
+  it('opens the confirm state for a folder whose subtree holds no models', async () => {
-    const manager = createManager(createApiClient());
+    const apiClient = createApiClient();
+    const manager = createManager(apiClient);
     manager.nonEmptyFolders = new Set(['', 'full']);
 
-    manager.showDeleteFolderModal('empty');
+    await manager.showDeleteFolderModal('empty');
 
     const modal = document.getElementById('deleteFolderModal');
     expect(modal.dataset.state).toBe('confirm');
     expect(confirmBtn().style.display).toBe('');
+    expect(confirmBtn().disabled).toBe(false);
     expect(manager._pendingDeleteFolderPath).toBe('empty');
     expect(modalManager.showModal).toHaveBeenCalledWith('deleteFolderModal');
+    // The prediction is confirmed against the real guard before the user can
+    // act on it.
+    expect(apiClient.deleteFolder).toHaveBeenCalledWith(
+      '/models/loras/empty', { dryRun: true }
+    );
   });
 
-  it('explains the refusal when the subtree still holds models', () => {
+  it('explains the refusal when the subtree still holds models', async () => {
-    const manager = createManager(createApiClient());
+    const conflict = Object.assign(new Error('still contains models'), {
+      code: 'not_empty',
+      manifest: { model_count: 2, excluded_model_count: 0 },
+    });
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn().mockRejectedValue(conflict),
+    });
+    const manager = createManager(apiClient);
     manager.nonEmptyFolders = new Set(['', 'full']);
 
-    manager.showDeleteFolderModal('full');
+    await manager.showDeleteFolderModal('full');
 
     const modal = document.getElementById('deleteFolderModal');
     expect(modal.dataset.state).toBe('blocked');
@@ -656,17 +670,134 @@ describe('SidebarManager folder deletion', () => {
     expect(manager._pendingDeleteFolderPath).toBeNull();
   });
 
-  it('treats an unknown folder as model-free when the models-only set is missing', () => {
+  it('treats an unknown folder as model-free when the models-only set is missing', async () => {
-    // nonEmptyFolders is null outside the include-empty tree; the server still
+    // nonEmptyFolders is null outside the include-empty tree; the dry run is
-    // refuses a non-empty folder, so the client falls back to the confirm state.
+    // what actually decides, so the prediction is only a starting point.
     const manager = createManager(createApiClient());
     manager.nonEmptyFolders = null;
 
-    manager.showDeleteFolderModal('empty');
+    await manager.showDeleteFolderModal('empty');
 
     expect(document.getElementById('deleteFolderModal').dataset.state).toBe('confirm');
   });
 
+  it('blocks a folder the tree shows as empty when only excluded models live there', async () => {
+    // The reported mismatch: excluded models are absent from the models-only
+    // set (so the node dims as empty), yet they are real weight files on disk
+    // and the delete guard refuses to cascade over them.
+    const conflict = Object.assign(
+      new Error('Folder still contains 3 model file(s), all excluded from the library'),
+      { code: 'not_empty', manifest: { model_count: 3, excluded_model_count: 3 } }
+    );
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn().mockRejectedValue(conflict),
+    });
+    const manager = createManager(apiClient);
+    manager.nonEmptyFolders = new Set(['', 'full']);
+
+    await manager.showDeleteFolderModal('Flux.1 D/test');
+
+    const modal = document.getElementById('deleteFolderModal');
+    expect(modal.dataset.state).toBe('blocked');
+    expect(confirmBtn().style.display).toBe('none');
+    expect(manager._pendingDeleteFolderPath).toBeNull();
+    // The message names the excluded models instead of contradicting the tree.
+    expect(modal.querySelector('[data-role="message"]').textContent)
+      .toContain('excluded from the library');
+    expect(apiClient.deleteFolder).toHaveBeenCalledWith(
+      '/models/loras/Flux.1 D/test', { dryRun: true }
+    );
+  });
+
+  it('reports how many model files block the delete when some are excluded', async () => {
+    const conflict = Object.assign(new Error('still contains models'), {
+      code: 'not_empty',
+      manifest: { model_count: 4, excluded_model_count: 1 },
+    });
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn().mockRejectedValue(conflict),
+    });
+    const manager = createManager(apiClient);
+    manager.nonEmptyFolders = new Set(['', 'full']);
+
+    await manager.showDeleteFolderModal('mixed');
+
+    expect(
+      document.getElementById('deleteFolderModal')
+        .querySelector('[data-role="message"]').textContent
+    ).toContain('4 model file(s)');
+  });
+
+  it('blocks the delete while a staged delete is still pending', async () => {
+    const busy = Object.assign(new Error('staged delete pending'), { code: 'busy' });
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn().mockRejectedValue(busy),
+    });
+    const manager = createManager(apiClient);
+    manager.nonEmptyFolders = new Set(['', 'full']);
+
+    await manager.showDeleteFolderModal('empty');
+
+    const modal = document.getElementById('deleteFolderModal');
+    expect(modal.dataset.state).toBe('busy');
+    expect(confirmBtn().style.display).toBe('none');
+  });
+
+  it('keeps the confirm button disabled until the check settles', async () => {
+    let release;
+    const apiClient = createApiClient({
+      fetchModelRoots: vi.fn(() => new Promise((resolve) => { release = resolve; })),
+    });
+    const manager = createManager(apiClient);
+    manager.nonEmptyFolders = new Set(['', 'full']);
+
+    const pending = manager.showDeleteFolderModal('empty');
+    expect(confirmBtn().disabled).toBe(true);
+
+    release({ roots: ['/models/loras'] });
+    await pending;
+
+    expect(confirmBtn().disabled).toBe(false);
+    expect(document.getElementById('deleteFolderModal').dataset.state).toBe('confirm');
+  });
+
+  it('ignores a dry-run answer that lands after the modal was dismissed', async () => {
+    let rejectProbe;
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn(() => new Promise((_resolve, reject) => { rejectProbe = reject; })),
+    });
+    const manager = createManager(apiClient);
+    manager.nonEmptyFolders = new Set(['', 'full']);
+
+    const pending = manager.showDeleteFolderModal('empty');
+    expect(document.getElementById('deleteFolderModal').dataset.state).toBe('confirm');
+
+    await vi.waitFor(() => expect(rejectProbe).toBeTypeOf('function'));
+
+    manager.hideDeleteFolderModal();
+    rejectProbe(Object.assign(new Error('still contains models'), {
+      code: 'not_empty',
+      manifest: { model_count: 1, excluded_model_count: 0 },
+    }));
+    await pending;
+
+    expect(document.getElementById('deleteFolderModal').dataset.state).toBe('confirm');
+  });
+
+  it('falls back to the tree prediction when the check fails for another reason', async () => {
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn().mockRejectedValue(new Error('network down')),
+    });
+    const manager = createManager(apiClient);
+    manager.nonEmptyFolders = new Set(['', 'full']);
+
+    await manager.showDeleteFolderModal('empty');
+
+    const modal = document.getElementById('deleteFolderModal');
+    expect(modal.dataset.state).toBe('confirm');
+    expect(confirmBtn().disabled).toBe(false);
+  });
+
   it('deletes the folder and offers the undo affordance for an empty one', async () => {
     const apiClient = createApiClient();
     const manager = createManager(apiClient);
@@ -732,6 +863,25 @@ describe('SidebarManager folder deletion', () => {
     expect(manager.refresh).not.toHaveBeenCalled();
   });
 
+  it('includes the model count in the stale-tree toast when the manifest has one', async () => {
+    const conflict = Object.assign(new Error('still contains models'), {
+      code: 'not_empty',
+      manifest: { model_count: 3, excluded_model_count: 3 },
+    });
+    const apiClient = createApiClient({
+      deleteFolder: vi.fn().mockRejectedValue(conflict),
+    });
+    const manager = createManager(apiClient);
+    manager.refresh = vi.fn().mockResolvedValue(undefined);
+
+    const success = await manager._deleteFolder('full');
+
+    expect(success).toBe(false);
+    expect(showToast).toHaveBeenCalledWith(
+      'sidebar.deleteFolderResult.notEmptyWithCount', { count: 3 }, 'warning'
+    );
+  });
+
   it('surfaces a busy folder with a staged delete', async () => {
     const busy = Object.assign(new Error('staged delete pending'), { code: 'busy' });
     const apiClient = createApiClient({

tests/frontend/managers/settingsManager.sidecarStorage.test.js

@@ -0,0 +1,340 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+
+vi.mock('../../../static/js/managers/ModalManager.js', () => ({
+    modalManager: {
+        closeModal: vi.fn(),
+    },
+}));
+
+vi.mock('../../../static/js/utils/uiHelpers.js', () => ({
+    showToast: vi.fn(),
+}));
+
+vi.mock('../../../static/js/state/index.js', () => {
+    const settings = {};
+    return {
+        state: {
+            global: {
+                settings,
+            },
+            loadingManager: {
+                showSimpleLoading: vi.fn(),
+                hide: vi.fn(),
+            },
+        },
+        createDefaultSettings: () => ({
+            language: 'en',
+            sidecar_storage_mode: 'alongside',
+            sidecar_storage_path: '',
+        }),
+    };
+});
+
+vi.mock('../../../static/js/api/modelApiFactory.js', () => ({
+    resetAndReload: vi.fn(),
+    getModelApiClient: vi.fn(),
+}));
+
+vi.mock('../../../static/js/utils/constants.js', () => ({
+    DOWNLOAD_PATH_TEMPLATES: {},
+    DEFAULT_PATH_TEMPLATES: {},
+    MAPPABLE_BASE_MODELS: [],
+    PATH_TEMPLATE_PLACEHOLDERS: {},
+    FILENAME_TEMPLATE_PLACEHOLDERS: [],
+    DEFAULT_FILENAME_TEMPLATES: { lora: '', checkpoint: '', embedding: '' },
+    DEFAULT_PRIORITY_TAG_CONFIG: {
+        lora: 'character, style',
+        checkpoint: 'base, guide',
+        embedding: 'hint',
+    },
+    getMappableBaseModelsDynamic: () => [],
+}));
+
+vi.mock('../../../static/js/utils/i18nHelpers.js', () => ({
+    translate: (_key, _params, fallback) => fallback ?? '',
+}));
+
+vi.mock('../../../static/js/i18n/index.js', () => ({
+    i18n: {
+        getCurrentLocale: () => 'en',
+        setLanguage: vi.fn().mockResolvedValue(),
+    },
+}));
+
+vi.mock('../../../static/js/components/shared/ModelCard.js', () => ({
+    configureModelCardVideo: vi.fn(),
+}));
+
+import { SettingsManager } from '../../../static/js/managers/SettingsManager.js';
+import { showToast } from '../../../static/js/utils/uiHelpers.js';
+import { resetAndReload } from '../../../static/js/api/modelApiFactory.js';
+import { state } from '../../../static/js/state/index.js';
+
+const createManager = () => {
+    state.global.settings = {};
+    const initSettingsSpy = vi
+        .spyOn(SettingsManager.prototype, 'initializeSettings')
+        .mockResolvedValue();
+    const initializeSpy = vi
+        .spyOn(SettingsManager.prototype, 'initialize')
+        .mockImplementation(() => {});
+
+    const manager = new SettingsManager();
+
+    initSettingsSpy.mockRestore();
+    initializeSpy.mockRestore();
+
+    return manager;
+};
+
+const appendSidecarControls = () => {
+    const select = document.createElement('select');
+    select.id = 'sidecarStorageMode';
+    ['alongside', 'centralized'].forEach((value) => {
+        const option = document.createElement('option');
+        option.value = value;
+        select.appendChild(option);
+    });
+
+    const pathSetting = document.createElement('div');
+    pathSetting.id = 'sidecarStoragePathSetting';
+    pathSetting.style.display = 'none';
+
+    const pathInput = document.createElement('input');
+    pathInput.id = 'sidecarStoragePath';
+
+    const migrateBtn = document.createElement('button');
+    migrateBtn.id = 'migrateSidecarsBtn';
+
+    document.body.append(select, pathSetting, pathInput, migrateBtn);
+    return { select, pathSetting, pathInput, migrateBtn };
+};
+
+const appendMigrationModal = () => {
+    const modal = document.createElement('div');
+    modal.id = 'sidecarMigrationConfirmModal';
+    modal.innerHTML = `
+        <h2 data-role="title"></h2>
+        <p data-role="message"></p>
+        <button data-action="confirm-sidecar-migration"></button>
+        <button data-action="cancel-sidecar-migration"></button>`;
+    document.body.appendChild(modal);
+    return modal;
+};
+
+const mockFetchOk = (payload = { success: true }) => {
+    global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: () => Promise.resolve(payload),
+    });
+};
+
+beforeEach(() => {
+    document.body.innerHTML = '';
+    vi.clearAllMocks();
+});
+
+afterEach(() => {
+    delete global.fetch;
+});
+
+describe('SettingsManager sidecar storage', () => {
+    describe('loadSidecarStorageSettings', () => {
+        it('loads alongside mode and hides the centralized path input', () => {
+            const manager = createManager();
+            const { select, pathSetting, pathInput } = appendSidecarControls();
+            state.global.settings = { sidecar_storage_mode: 'alongside', sidecar_storage_path: '/data/sidecars' };
+
+            manager.loadSidecarStorageSettings();
+
+            expect(select.value).toBe('alongside');
+            expect(pathInput.value).toBe('/data/sidecars');
+            expect(pathSetting.style.display).toBe('none');
+            expect(manager._loadedSidecarStorageMode).toBe('alongside');
+        });
+
+        it('loads centralized mode and shows the path input', () => {
+            const manager = createManager();
+            const { select, pathSetting } = appendSidecarControls();
+            state.global.settings = { sidecar_storage_mode: 'centralized' };
+
+            manager.loadSidecarStorageSettings();
+
+            expect(select.value).toBe('centralized');
+            expect(pathSetting.style.display).toBe('block');
+            expect(manager._loadedSidecarStorageMode).toBe('centralized');
+        });
+
+        it('falls back to alongside for unknown stored modes', () => {
+            const manager = createManager();
+            const { select } = appendSidecarControls();
+            state.global.settings = { sidecar_storage_mode: 'bogus' };
+
+            manager.loadSidecarStorageSettings();
+
+            expect(select.value).toBe('alongside');
+        });
+    });
+
+    describe('handleSidecarStorageModeChange', () => {
+        it('does not prompt for migration when the mode is unchanged', async () => {
+            const manager = createManager();
+            const { select } = appendSidecarControls();
+            appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'alongside' };
+            manager._loadedSidecarStorageMode = 'alongside';
+            select.value = 'alongside';
+            mockFetchOk();
+
+            await manager.handleSidecarStorageModeChange();
+
+            expect(global.fetch).not.toHaveBeenCalledWith(
+                '/api/lm/sidecars/migrate',
+                expect.anything()
+            );
+            expect(showToast).toHaveBeenCalledWith(
+                'toast.settings.settingsUpdated',
+                expect.anything(),
+                'success'
+            );
+        });
+
+        it('migrates to centralized after the user confirms the prompt', async () => {
+            const manager = createManager();
+            const { select, pathSetting } = appendSidecarControls();
+            const modal = appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'alongside' };
+            manager._loadedSidecarStorageMode = 'alongside';
+            select.value = 'centralized';
+            mockFetchOk();
+
+            const changePromise = manager.handleSidecarStorageModeChange();
+
+            await vi.waitFor(() => expect(modal.classList.contains('show')).toBe(true));
+            modal.querySelector('[data-action="confirm-sidecar-migration"]').click();
+            await changePromise;
+
+            expect(state.global.settings.sidecar_storage_mode).toBe('centralized');
+            expect(pathSetting.style.display).toBe('block');
+            expect(global.fetch).toHaveBeenCalledWith('/api/lm/sidecars/migrate', expect.objectContaining({
+                method: 'POST',
+                body: JSON.stringify({ direction: 'to_centralized', force: true }),
+            }));
+            expect(showToast).toHaveBeenCalledWith('settings.sidecarStorage.migrateSuccess', {}, 'success');
+            expect(resetAndReload).toHaveBeenCalledWith(true);
+            expect(modal.classList.contains('show')).toBe(false);
+        });
+
+        it('shows a deferred notice and skips migration when the user cancels', async () => {
+            const manager = createManager();
+            const { select } = appendSidecarControls();
+            const modal = appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'centralized' };
+            manager._loadedSidecarStorageMode = 'centralized';
+            select.value = 'alongside';
+            mockFetchOk();
+
+            const changePromise = manager.handleSidecarStorageModeChange();
+            await vi.waitFor(() => expect(modal.classList.contains('show')).toBe(true));
+            modal.querySelector('[data-action="cancel-sidecar-migration"]').click();
+            await changePromise;
+
+            const migrateCalls = global.fetch.mock.calls.filter(([url]) => url === '/api/lm/sidecars/migrate');
+            expect(migrateCalls).toHaveLength(0);
+            expect(showToast).toHaveBeenCalledWith('settings.sidecarStorage.migrationDeferred', {}, 'info');
+        });
+    });
+
+    describe('confirmAndMigrateSidecars', () => {
+        it('derives the migration direction from the saved mode', async () => {
+            const manager = createManager();
+            appendSidecarControls();
+            const modal = appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'centralized' };
+            mockFetchOk();
+
+            const confirmPromise = manager.confirmAndMigrateSidecars();
+            await vi.waitFor(() => expect(modal.classList.contains('show')).toBe(true));
+            modal.querySelector('[data-action="confirm-sidecar-migration"]').click();
+            await confirmPromise;
+
+            expect(global.fetch).toHaveBeenCalledWith('/api/lm/sidecars/migrate', expect.objectContaining({
+                body: JSON.stringify({ direction: 'to_centralized', force: true }),
+            }));
+        });
+    });
+
+    describe('migrateSidecars', () => {
+        it('surfaces backend failures as an error toast', async () => {
+            const manager = createManager();
+            const { migrateBtn } = appendSidecarControls();
+            mockFetchOk({ success: false, error: 'disk full' });
+
+            await manager.migrateSidecars('to_alongside');
+
+            expect(showToast).toHaveBeenCalledWith(
+                'settings.sidecarStorage.migrateFailed',
+                { message: 'disk full' },
+                'error'
+            );
+            expect(resetAndReload).not.toHaveBeenCalled();
+            expect(migrateBtn.disabled).toBe(false);
+        });
+    });
+
+    describe('handleSidecarStoragePathChange', () => {
+        it('offers root relocation when the path changes in centralized mode', async () => {
+            const manager = createManager();
+            const { pathInput } = appendSidecarControls();
+            const modal = appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'centralized', sidecar_storage_path: '/old/root' };
+            manager._loadedSidecarStoragePath = '/old/root';
+            pathInput.value = '/new/root';
+            mockFetchOk();
+
+            const changePromise = manager.handleSidecarStoragePathChange();
+            await vi.waitFor(() => expect(modal.classList.contains('show')).toBe(true));
+            modal.querySelector('[data-action="confirm-sidecar-migration"]').click();
+            await changePromise;
+
+            expect(global.fetch).toHaveBeenCalledWith('/api/lm/sidecars/migrate', expect.objectContaining({
+                body: JSON.stringify({ direction: 'relocate_root', force: true, old_root: '/old/root' }),
+            }));
+            expect(manager._loadedSidecarStoragePath).toBe('/new/root');
+        });
+
+        it('does not prompt when the path changes in alongside mode', async () => {
+            const manager = createManager();
+            const { pathInput } = appendSidecarControls();
+            appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'alongside', sidecar_storage_path: '/old/root' };
+            manager._loadedSidecarStoragePath = '/old/root';
+            pathInput.value = '/new/root';
+            mockFetchOk();
+
+            await manager.handleSidecarStoragePathChange();
+
+            const migrateCalls = global.fetch.mock.calls.filter(([url]) => url === '/api/lm/sidecars/migrate');
+            expect(migrateCalls).toHaveLength(0);
+        });
+
+        it('shows a deferred notice when relocation is cancelled', async () => {
+            const manager = createManager();
+            const { pathInput } = appendSidecarControls();
+            const modal = appendMigrationModal();
+            state.global.settings = { sidecar_storage_mode: 'centralized', sidecar_storage_path: '/old/root' };
+            manager._loadedSidecarStoragePath = '/old/root';
+            pathInput.value = '/new/root';
+            mockFetchOk();
+
+            const changePromise = manager.handleSidecarStoragePathChange();
+            await vi.waitFor(() => expect(modal.classList.contains('show')).toBe(true));
+            modal.querySelector('[data-action="cancel-sidecar-migration"]').click();
+            await changePromise;
+
+            const migrateCalls = global.fetch.mock.calls.filter(([url]) => url === '/api/lm/sidecars/migrate');
+            expect(migrateCalls).toHaveLength(0);
+            expect(showToast).toHaveBeenCalledWith('settings.sidecarStorage.migrationDeferred', {}, 'info');
+        });
+    });
+});

tests/routes/test_misc_routes.py

@@ -23,6 +23,7 @@ from py.routes.handlers.misc_handlers import (
     NodeRegistryHandler,
     ServiceRegistryAdapter,
     SettingsHandler,
+    SidecarMigrationHandler,
     _collect_comfyui_session_logs,
     _is_wsl,
     _wsl_to_windows_path,
@@ -2557,3 +2558,123 @@ async def test_get_model_versions_status_supported_type_stays_interactive():
             "hasBeenDownloaded": False,
         }
     ]
+
+
+class DummySidecarMigrationUseCase:
+    def __init__(self, result):
+        self.result = result
+        self.calls = []
+
+    async def execute_with_error_handling(self, *, direction, progress_cb=None, force=False, old_root=None):
+        self.calls.append({"direction": direction, "force": force, "old_root": old_root})
+        return self.result
+
+
+def _sidecar_migration_handler(result):
+    use_case = DummySidecarMigrationUseCase(result)
+    handler = SidecarMigrationHandler(
+        use_case_factory=lambda: use_case,
+        progress_callback_factory=lambda: None,
+    )
+    return handler, use_case
+
+
+@pytest.mark.asyncio
+async def test_sidecar_migration_handler_runs_to_centralized():
+    result = {"success": True, "direction": "to_centralized", "moved": 3}
+    handler, use_case = _sidecar_migration_handler(result)
+
+    response = await handler.migrate_sidecars(
+        FakeRequest(json_data={"direction": "to_centralized", "force": True})  # pyright: ignore[reportArgumentType]
+    )
+    payload = _json_payload(response)
+
+    assert response.status == 200
+    assert payload["success"] is True
+    assert payload["moved"] == 3
+    assert use_case.calls == [{"direction": "to_centralized", "force": True, "old_root": ""}]
+
+
+@pytest.mark.asyncio
+async def test_sidecar_migration_handler_rejects_bad_direction():
+    handler, use_case = _sidecar_migration_handler({"success": True})
+
+    response = await handler.migrate_sidecars(
+        FakeRequest(json_data={"direction": "sideways"})  # pyright: ignore[reportArgumentType]
+    )
+    payload = _json_payload(response)
+
+    assert response.status == 400
+    assert payload["success"] is False
+    assert use_case.calls == []
+
+
+@pytest.mark.asyncio
+async def test_sidecar_migration_handler_accepts_get_query_params():
+    result = {"success": True, "direction": "to_alongside", "moved": 0}
+    handler, use_case = _sidecar_migration_handler(result)
+
+    response = await handler.migrate_sidecars(
+        FakeRequest(  # pyright: ignore[reportArgumentType]
+            query={"direction": "to_alongside", "force": "true"},
+            method="GET",
+        )
+    )
+    payload = _json_payload(response)
+
+    assert response.status == 200
+    assert payload["success"] is True
+    assert use_case.calls == [{"direction": "to_alongside", "force": True, "old_root": ""}]
+
+
+@pytest.mark.asyncio
+async def test_sidecar_migration_handler_guard_refusal_is_400():
+    result = {"success": False, "error": "sidecar storage is already centralized"}
+    handler, use_case = _sidecar_migration_handler(result)
+
+    response = await handler.migrate_sidecars(
+        FakeRequest(json_data={"direction": "to_centralized"})  # pyright: ignore[reportArgumentType]
+    )
+    payload = _json_payload(response)
+
+    assert response.status == 400
+    assert payload["success"] is False
+    assert "already centralized" in payload["error"]
+    assert use_case.calls == [{"direction": "to_centralized", "force": False, "old_root": ""}]
+
+
+@pytest.mark.asyncio
+async def test_sidecar_migration_handler_relocate_root_passes_old_root():
+    result = {"success": True, "direction": "relocate_root", "moved": 5}
+    handler, use_case = _sidecar_migration_handler(result)
+
+    response = await handler.migrate_sidecars(
+        FakeRequest(  # pyright: ignore[reportArgumentType]
+            json_data={
+                "direction": "relocate_root",
+                "old_root": "/old/sidecars",
+                "force": True,
+            }
+        )
+    )
+    payload = _json_payload(response)
+
+    assert response.status == 200
+    assert payload["success"] is True
+    assert use_case.calls == [
+        {"direction": "relocate_root", "force": True, "old_root": "/old/sidecars"}
+    ]
+
+
+@pytest.mark.asyncio
+async def test_sidecar_migration_handler_relocate_root_requires_old_root():
+    handler, use_case = _sidecar_migration_handler({"success": True})
+
+    response = await handler.migrate_sidecars(
+        FakeRequest(json_data={"direction": "relocate_root"})  # pyright: ignore[reportArgumentType]
+    )
+    payload = _json_payload(response)
+
+    assert response.status == 400
+    assert "old_root" in payload["error"]
+    assert use_case.calls == []

tests/services/test_centralized_sidecar_storage.py

@@ -0,0 +1,363 @@
+"""Centralized sidecar storage: lifecycle flows (delete/move/rename/scans)."""
+
+from __future__ import annotations
+
+import json
+import os
+from pathlib import Path
+from typing import Any, Dict, List
+from unittest.mock import AsyncMock
+
+import pytest
+
+from py.config import config
+from py.services.checkpoint_scanner import CheckpointScanner
+from py.services.model_lifecycle_service import (
+    ModelLifecycleService,
+    delete_model_artifacts,
+)
+from py.services.pending_delete_service import PendingDeleteService
+from py.services.settings_manager import get_settings_manager
+from py.utils.metadata_manager import MetadataManager
+from py.utils.sidecar_paths import root_mirror_component
+
+
+def _normalize(path) -> str:
+    return str(path).replace(os.sep, "/")
+
+
+@pytest.fixture
+def library_root(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
+    """Single checkpoint root under tmp_path; every other root emptied."""
+
+    root = tmp_path / "checkpoints"
+    root.mkdir()
+    for attr, value in (
+        ("loras_roots", []),
+        ("base_models_roots", [str(root)]),
+        ("checkpoints_roots", [str(root)]),
+        ("embeddings_roots", []),
+        ("other_roots", []),
+        ("extra_loras_roots", []),
+        ("extra_checkpoints_roots", []),
+        ("extra_unet_roots", []),
+        ("extra_embeddings_roots", []),
+    ):
+        monkeypatch.setattr(config, attr, value, raising=False)
+    return root
+
+
+@pytest.fixture
+def centralized(library_root: Path, tmp_path: Path) -> Path:
+    """Enable centralized mode rooted at tmp_path/sidecars."""
+
+    sidecar_root = tmp_path / "sidecars"
+    settings = get_settings_manager()
+    settings.set("sidecar_storage_mode", "centralized")
+    settings.set("sidecar_storage_path", str(sidecar_root))
+    return sidecar_root
+
+
+def _mirror_dir(library_root: Path, sidecar_root: Path, *rel: str) -> Path:
+    """Expected mirror directory for a library-relative path."""
+
+    library = get_settings_manager().get_active_library_name()
+    component = root_mirror_component(str(library_root))
+    return sidecar_root.joinpath(library, component, *rel)
+
+
+def _write_sidecar(
+    mirror_dir: Path,
+    stem: str,
+    *,
+    file_path: str,
+    preview_name: str | None = None,
+    extra: Dict[str, Any] | None = None,
+) -> Path:
+    mirror_dir.mkdir(parents=True, exist_ok=True)
+    payload: Dict[str, Any] = {
+        "file_name": stem,
+        "file_path": _normalize(file_path),
+    }
+    if preview_name:
+        payload["preview_url"] = _normalize(mirror_dir / preview_name)
+        (mirror_dir / preview_name).write_bytes(b"preview")
+    if extra:
+        payload.update(extra)
+    metadata_path = mirror_dir / f"{stem}.metadata.json"
+    metadata_path.write_text(json.dumps(payload), encoding="utf-8")
+    return metadata_path
+
+
+@pytest.mark.asyncio
+async def test_delete_model_artifacts_centralized(
+    library_root: Path, centralized: Path
+):
+    model = library_root / "model.safetensors"
+    model.write_bytes(b"weights")
+    mirror = _mirror_dir(library_root, centralized)
+    _write_sidecar(mirror, "model", file_path=model, preview_name="model.preview.webp")
+
+    deleted = await delete_model_artifacts(str(library_root), "model")
+
+    assert not model.exists()
+    assert not (mirror / "model.metadata.json").exists()
+    assert not (mirror / "model.preview.webp").exists()
+    assert any(path.endswith("model.safetensors") for path in deleted)
+    assert "model.metadata.json" in deleted
+    assert "model.preview.webp" in deleted
+
+
+@pytest.mark.asyncio
+async def test_delete_model_artifacts_alongside_still_siblings(
+    library_root: Path,
+):
+    """Alongside mode (default) keeps deleting sidecars next to the model."""
+
+    model = library_root / "model.safetensors"
+    model.write_bytes(b"weights")
+    sidecar = library_root / "model.metadata.json"
+    sidecar.write_text("{}", encoding="utf-8")
+    preview = library_root / "model.preview.webp"
+    preview.write_bytes(b"preview")
+
+    await delete_model_artifacts(str(library_root), "model")
+
+    assert not model.exists()
+    assert not sidecar.exists()
+    assert not preview.exists()
+
+
+def test_enumerate_model_artifacts_centralized(
+    library_root: Path, centralized: Path
+):
+    model = library_root / "model.safetensors"
+    model.write_bytes(b"weights")
+    mirror = _mirror_dir(library_root, centralized)
+    _write_sidecar(mirror, "model", file_path=model, preview_name="model.preview.png")
+
+    service = PendingDeleteService.__new__(PendingDeleteService)
+    artifacts = service._enumerate_model_artifacts(
+        str(library_root), "model", ".safetensors"
+    )
+
+    assert artifacts == [
+        os.path.abspath(str(model)),
+        os.path.abspath(str(mirror / "model.metadata.json")),
+        os.path.abspath(str(mirror / "model.preview.png")),
+    ]
+
+
+class _RecordingScanner:
+    def __init__(self):
+        self.calls: List[tuple] = []
+        self.model_type = "lora"
+
+    async def update_single_model_cache(self, old_path, new_path, metadata):
+        self.calls.append((old_path, new_path, metadata))
+
+
+class _PassthroughMetadataManager:
+    async def save_metadata(self, path: str, metadata):
+        await MetadataManager.save_metadata(path, metadata)
+        return True
+
+
+async def _json_metadata_loader(path: str) -> Dict[str, object]:
+    with open(path, "r", encoding="utf-8") as handle:
+        return json.load(handle)
+
+
+@pytest.mark.asyncio
+async def test_rename_model_centralized(library_root: Path, centralized: Path):
+    model = library_root / "model.safetensors"
+    model.write_bytes(b"weights")
+    mirror = _mirror_dir(library_root, centralized)
+    _write_sidecar(mirror, "model", file_path=model, preview_name="model.preview.webp")
+
+    service = ModelLifecycleService(
+        scanner=_RecordingScanner(),
+        metadata_manager=_PassthroughMetadataManager(),
+        metadata_loader=_json_metadata_loader,
+    )
+
+    result = await service.rename_model(
+        file_path=_normalize(model), new_file_name="renamed"
+    )
+
+    assert result["success"] is True
+    renamed = library_root / "renamed.safetensors"
+    assert renamed.exists()
+    assert not model.exists()
+
+    # Mirror sidecar/preview renamed with the model; nothing left alongside.
+    assert (mirror / "renamed.metadata.json").exists()
+    assert (mirror / "renamed.preview.webp").exists()
+    assert not (mirror / "model.metadata.json").exists()
+    assert not (mirror / "model.preview.webp").exists()
+    assert not (library_root / "renamed.metadata.json").exists()
+    assert not (library_root / "renamed.preview.webp").exists()
+
+    saved = json.loads((mirror / "renamed.metadata.json").read_text())
+    assert saved["file_name"] == "renamed"
+    assert saved["file_path"].endswith("renamed.safetensors")
+    assert saved["preview_url"].endswith("renamed.preview.webp")
+    assert str(mirror).replace(os.sep, "/") in saved["preview_url"]
+
+
+@pytest.mark.asyncio
+async def test_move_model_centralized(
+    library_root: Path, centralized: Path, monkeypatch: pytest.MonkeyPatch
+):
+    source_dir = library_root / "old"
+    source_dir.mkdir()
+    model = source_dir / "model.safetensors"
+    model.write_bytes(b"weights")
+    target_dir = library_root / "new"
+
+    old_mirror = _mirror_dir(library_root, centralized, "old")
+    _write_sidecar(
+        old_mirror, "model", file_path=model, preview_name="model.preview.webp"
+    )
+
+    scanner = CheckpointScanner()
+    monkeypatch.setattr(
+        scanner, "update_single_model_cache", AsyncMock(return_value=True)
+    )
+
+    result = await scanner.move_model(_normalize(model), _normalize(target_dir))
+
+    assert result is not None
+    moved_model = target_dir / "model.safetensors"
+    assert moved_model.exists()
+    assert not model.exists()
+
+    new_mirror = _mirror_dir(library_root, centralized, "new")
+    assert (new_mirror / "model.metadata.json").exists()
+    assert (new_mirror / "model.preview.webp").exists()
+    assert not (old_mirror / "model.metadata.json").exists()
+    assert not (old_mirror / "model.preview.webp").exists()
+
+    saved = json.loads((new_mirror / "model.metadata.json").read_text())
+    assert saved["file_path"].endswith("new/model.safetensors")
+    assert saved["preview_url"].endswith("model.preview.webp")
+    assert str(new_mirror).replace(os.sep, "/") in saved["preview_url"]
+
+
+class _FakeCache:
+    def __init__(self, raw_data: List[Dict[str, Any]]):
+        self.raw_data = raw_data
+        self.all_folders: List[str] = []
+        self.folders: List[str] = []
+
+    def remove_from_version_index(self, _item) -> None:
+        pass
+
+    def rebuild_version_index(self) -> None:
+        pass
+
+    async def resort(self) -> None:
+        pass
+
+
+@pytest.mark.asyncio
+async def test_rename_known_folder_centralized(
+    library_root: Path, centralized: Path, monkeypatch: pytest.MonkeyPatch
+):
+    # The caller (ModelFileService.rename_folder) has already renamed the
+    # model directory on disk when the scanner is asked to re-key records.
+    old_dir = library_root / "oldfolder"
+    new_dir = library_root / "newfolder"
+    new_dir.mkdir()
+    model = new_dir / "model.safetensors"
+    model.write_bytes(b"weights")
+
+    old_model_path = old_dir / "model.safetensors"
+    old_mirror = _mirror_dir(library_root, centralized, "oldfolder")
+    _write_sidecar(
+        old_mirror, "model", file_path=old_model_path, preview_name="model.preview.webp"
+    )
+
+    cache_entry: Dict[str, Any] = {
+        "file_path": _normalize(old_model_path),
+        "folder": "oldfolder",
+        "preview_url": _normalize(old_mirror / "model.preview.webp"),
+        "sha256": "",
+    }
+    scanner = CheckpointScanner()
+    scanner._cache = _FakeCache([cache_entry])
+    monkeypatch.setattr(scanner, "_persist_current_cache", AsyncMock())
+
+    changed = await scanner.rename_known_folder(
+        "oldfolder",
+        "newfolder",
+        previous_path=str(old_dir),
+        new_path=str(new_dir),
+    )
+
+    assert changed is True
+
+    new_mirror = _mirror_dir(library_root, centralized, "newfolder")
+    assert (new_mirror / "model.metadata.json").exists()
+    assert (new_mirror / "model.preview.webp").exists()
+    assert not old_mirror.exists()
+
+    saved = json.loads((new_mirror / "model.metadata.json").read_text())
+    assert saved["file_path"] == _normalize(model)
+    assert saved["preview_url"] == _normalize(new_mirror / "model.preview.webp")
+
+    assert cache_entry["file_path"] == _normalize(model)
+    assert cache_entry["folder"] == "newfolder"
+    assert cache_entry["preview_url"] == _normalize(
+        new_mirror / "model.preview.webp"
+    )
+
+
+@pytest.mark.asyncio
+async def test_pending_models_mirror_walk(library_root: Path, centralized: Path):
+    model = library_root / "model.safetensors"
+    model.write_bytes(b"weights")
+    mirror = _mirror_dir(library_root, centralized)
+    _write_sidecar(
+        mirror,
+        "model",
+        file_path=model,
+        extra={"hash_status": "pending", "sha256": ""},
+    )
+    # Orphan sidecar: recorded model path is gone and no stem match exists.
+    _write_sidecar(
+        mirror,
+        "ghost",
+        file_path=library_root / "ghost.safetensors",
+        extra={"hash_status": "pending", "sha256": ""},
+    )
+
+    scanner = CheckpointScanner()
+    pending = await scanner._find_pending_models_from_filesystem()
+
+    assert len(pending) == 1
+    assert pending[0]["file_path"] == _normalize(model)
+    assert pending[0]["hash_status"] == "pending"
+
+
+@pytest.mark.asyncio
+async def test_pending_models_mirror_walk_uses_stem_fallback(
+    library_root: Path, centralized: Path
+):
+    """A stale recorded file_path falls back to probing by stem + extension."""
+
+    model = library_root / "model.safetensors"
+    model.write_bytes(b"weights")
+    mirror = _mirror_dir(library_root, centralized)
+    _write_sidecar(
+        mirror,
+        "model",
+        file_path=library_root / "renamed-away.safetensors",
+        extra={"hash_status": "pending", "sha256": ""},
+    )
+
+    scanner = CheckpointScanner()
+    pending = await scanner._find_pending_models_from_filesystem()
+
+    assert len(pending) == 1
+    assert pending[0]["file_path"] == _normalize(model)

tests/services/test_model_file_service.py

@@ -11,15 +11,19 @@ from py.services.model_file_service import ModelMoveService
 
 
 class FakeScanner:
-    def __init__(self, roots: List[Path]) -> None:
+    def __init__(self, roots: List[Path], excluded: List[str] | None = None) -> None:
         self._roots = [str(root) for root in roots]
         self.known_folders: List[str] = []
         self.removed_folders: List[str] = []
         self.renamed_folders: List[tuple] = []
+        self._excluded = list(excluded or [])
 
     def get_model_roots(self) -> List[str]:
         return list(self._roots)
 
+    def get_excluded_models(self) -> List[str]:
+        return list(self._excluded)
+
     async def add_known_folder(self, folder: str) -> None:
         self.known_folders.append(folder)
 
@@ -30,6 +34,12 @@ class FakeScanner:
         self.renamed_folders.append((previous, current, kwargs))
 
 
+class ScannerWithoutExcludedAccessor(FakeScanner):
+    """Scanner stand-in predating ``get_excluded_models()``."""
+
+    get_excluded_models = None  # type: ignore[assignment]
+
+
 @pytest.mark.asyncio
 async def test_create_folder_creates_directory_and_registers_it(tmp_path: Path):
     scanner = FakeScanner([tmp_path])
@@ -149,11 +159,90 @@ async def test_delete_folder_refuses_when_models_live_below(tmp_path: Path):
     assert result["success"] is False
     assert result["code"] == "not_empty"
     assert result["manifest"]["model_count"] == 1
+    assert result["manifest"]["excluded_model_count"] == 0
     assert target.exists()
     assert model_file.exists()
     assert scanner.removed_folders == []
 
 
+@pytest.mark.asyncio
+async def test_delete_folder_manifest_marks_models_excluded_from_the_library(tmp_path: Path):
+    """Excluded models are invisible to the model lists but still block the
+    cascade, so the manifest has to say so — the folder sidebar otherwise shows
+    the folder as empty and the refusal reads as a bug."""
+    target = _make_nested(tmp_path)
+    model_file = target / "hidden.safetensors"
+    model_file.write_text("weights", encoding="utf-8")
+    scanner = FakeScanner([tmp_path], excluded=[str(model_file)])
+    service = ModelMoveService(scanner, "lora")
+
+    result = await service.delete_folder(str(target))
+
+    assert result["success"] is False
+    assert result["code"] == "not_empty"
+    assert result["manifest"]["model_count"] == 1
+    assert result["manifest"]["excluded_model_count"] == 1
+    assert "excluded" in result["error"]
+    assert model_file.exists()
+
+
+@pytest.mark.asyncio
+async def test_delete_folder_error_splits_excluded_from_visible_models(tmp_path: Path):
+    target = _make_nested(tmp_path)
+    visible = target / "visible.safetensors"
+    hidden = target / "hidden.safetensors"
+    visible.write_text("weights", encoding="utf-8")
+    hidden.write_text("weights", encoding="utf-8")
+    scanner = FakeScanner([tmp_path], excluded=[str(hidden)])
+    service = ModelMoveService(scanner, "lora")
+
+    result = await service.delete_folder(str(target))
+
+    assert result["manifest"]["model_count"] == 2
+    assert result["manifest"]["excluded_model_count"] == 1
+    assert "1 of them excluded" in result["error"]
+
+
+@pytest.mark.asyncio
+async def test_delete_folder_does_not_claim_excluded_for_visible_models(tmp_path: Path):
+    target = _make_nested(tmp_path)
+    (target / "model.safetensors").write_text("weights", encoding="utf-8")
+    # An excluded model elsewhere in the library must not be attributed here.
+    scanner = FakeScanner([tmp_path], excluded=[str(tmp_path / "other" / "other.safetensors")])
+    service = ModelMoveService(scanner, "lora")
+
+    result = await service.delete_folder(str(target))
+
+    assert result["manifest"]["excluded_model_count"] == 0
+    assert "excluded" not in result["error"]
+
+
+@pytest.mark.asyncio
+async def test_delete_folder_works_without_the_excluded_accessor(tmp_path: Path):
+    target = _make_nested(tmp_path)
+    (target / "model.safetensors").write_text("weights", encoding="utf-8")
+    scanner = ScannerWithoutExcludedAccessor([tmp_path])
+    service = ModelMoveService(scanner, "lora")
+
+    result = await service.delete_folder(str(target))
+
+    assert result["success"] is False
+    assert result["manifest"]["excluded_model_count"] == 0
+
+
+@pytest.mark.asyncio
+async def test_delete_folder_success_manifest_carries_excluded_model_count(tmp_path: Path):
+    target = _make_nested(tmp_path)
+    (target / "leftover.webp").write_text("preview", encoding="utf-8")
+    scanner = FakeScanner([tmp_path], excluded=[str(tmp_path / "elsewhere.safetensors")])
+    service = ModelMoveService(scanner, "lora")
+
+    result = await service.delete_folder(str(target), dry_run=True)
+
+    assert result["success"] is True
+    assert result["excluded_model_count"] == 0
+
+
 @pytest.mark.asyncio
 async def test_delete_folder_refuses_while_a_staged_delete_is_pending(tmp_path: Path):
     target = _make_nested(tmp_path)

tests/services/use_cases/test_sidecar_migration_use_case.py

@@ -0,0 +1,506 @@
+"""Sidecar migration use case: layout moves, conflicts, guards."""
+
+from __future__ import annotations
+
+import json
+import os
+from pathlib import Path
+from typing import Any, Dict, List
+
+import pytest
+
+from py.config import config
+from py.services.settings_manager import get_settings_manager
+from py.services.use_cases.sidecar_migration_use_case import SidecarMigrationUseCase
+from py.utils.sidecar_paths import root_mirror_component
+
+
+def _normalize(path) -> str:
+    return str(path).replace(os.sep, "/")
+
+
+@pytest.fixture
+def library_root(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
+    """Single lora root under tmp_path; every other root emptied."""
+
+    root = tmp_path / "loras"
+    root.mkdir()
+    for attr, value in (
+        ("loras_roots", [str(root)]),
+        ("base_models_roots", []),
+        ("checkpoints_roots", []),
+        ("embeddings_roots", []),
+        ("other_roots", []),
+        ("extra_loras_roots", []),
+        ("extra_checkpoints_roots", []),
+        ("extra_unet_roots", []),
+        ("extra_embeddings_roots", []),
+    ):
+        monkeypatch.setattr(config, attr, value, raising=False)
+    return root
+
+
+@pytest.fixture
+def sidecar_root(tmp_path: Path) -> Path:
+    """Configured centralized root (mode-independent for migration)."""
+
+    root = tmp_path / "sidecars"
+    get_settings_manager().set("sidecar_storage_path", str(root))
+    return root
+
+
+def _set_mode(mode: str) -> None:
+    get_settings_manager().set("sidecar_storage_mode", mode)
+
+
+def _mirror_dir(library_root: Path, sidecar_root: Path, *rel: str) -> Path:
+    """Expected mirror directory for a library-relative path."""
+
+    library = get_settings_manager().get_active_library_name()
+    component = root_mirror_component(str(library_root))
+    return sidecar_root.joinpath(library, component, *rel)
+
+
+def _write_model(directory: Path, stem: str) -> Path:
+    directory.mkdir(parents=True, exist_ok=True)
+    model = directory / f"{stem}.safetensors"
+    model.write_bytes(b"weights")
+    return model
+
+
+def _write_sidecar(directory: Path, stem: str, model: Path, *, preview_ext: str | None = ".preview.webp") -> Path:
+    directory.mkdir(parents=True, exist_ok=True)
+    payload: Dict[str, Any] = {
+        "file_name": stem,
+        "file_path": _normalize(model),
+    }
+    if preview_ext:
+        payload["preview_url"] = _normalize(directory / f"{stem}{preview_ext}")
+    sidecar = directory / f"{stem}.metadata.json"
+    sidecar.write_text(json.dumps(payload), encoding="utf-8")
+    return sidecar
+
+
+class _FakeCache:
+    def __init__(self, raw_data: List[Dict[str, Any]]) -> None:
+        self.raw_data = raw_data
+
+    async def update_preview_url(
+        self, file_path: str, preview_url: str, preview_nsfw_level: int
+    ) -> bool:
+        for item in self.raw_data:
+            if item["file_path"] == file_path:
+                item["preview_url"] = preview_url
+                item["preview_nsfw_level"] = preview_nsfw_level
+                return True
+        return False
+
+
+class _FakeScanner:
+    def __init__(self, raw_data: List[Dict[str, Any]]) -> None:
+        self._cache = _FakeCache(raw_data)
+        self.persist_calls = 0
+
+    async def get_cached_data(self) -> _FakeCache:
+        return self._cache
+
+    async def _persist_current_cache(self) -> None:
+        self.persist_calls += 1
+
+
+def _make_use_case(model_paths: List[str]) -> SidecarMigrationUseCase:
+    scanner = _FakeScanner([{"file_path": path} for path in model_paths])
+
+    async def scanner_factory() -> _FakeScanner:
+        return scanner
+
+    use_case = SidecarMigrationUseCase(
+        scanner_factories=(("lora", scanner_factory),),
+        settings_service=get_settings_manager(),
+    )
+    use_case._test_scanner = scanner  # expose for cache-reconcile assertions
+    return use_case
+
+
+class _ProgressRecorder:
+    def __init__(self) -> None:
+        self.payloads: List[Dict[str, Any]] = []
+
+    async def on_progress(self, payload: Dict[str, Any]) -> None:
+        self.payloads.append(payload)
+
+
+@pytest.mark.asyncio
+async def test_migrate_to_centralized_moves_sidecar_and_previews(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("centralized")
+    model = _write_model(library_root / "sub", "model")
+    sidecar = _write_sidecar(library_root / "sub", "model", model)
+    preview = library_root / "sub" / "model.preview.webp"
+    preview.write_bytes(b"preview")
+    extra_preview = library_root / "sub" / "model.png"
+    extra_preview.write_bytes(b"extra")
+
+    recorder = _ProgressRecorder()
+    use_case = _make_use_case([str(model)])
+    summary = await use_case.migrate_to_centralized(recorder, force=True)
+
+    assert summary["success"] is True
+    assert summary["direction"] == "to_centralized"
+    assert summary["moved"] == 3
+    assert summary["models_moved"] == 1
+    assert summary["skipped"] == 0
+    assert summary["conflicts"] == 0
+    assert summary["errors"] == []
+
+    mirror = _mirror_dir(library_root, sidecar_root, "sub")
+    assert not sidecar.exists()
+    assert not preview.exists()
+    assert not extra_preview.exists()
+    moved_sidecar = mirror / "model.metadata.json"
+    assert moved_sidecar.exists()
+    assert (mirror / "model.preview.webp").exists()
+    assert (mirror / "model.png").exists()
+    # Model files never move.
+    assert model.exists()
+
+    metadata = json.loads(moved_sidecar.read_text(encoding="utf-8"))
+    assert metadata["file_path"] == _normalize(model)
+    assert metadata["file_name"] == "model"
+    # Recorded extension wins when rewriting preview_url.
+    assert metadata["preview_url"] == _normalize(mirror / "model.preview.webp")
+
+    statuses = [payload["status"] for payload in recorder.payloads]
+    assert statuses[0] == "started"
+    assert statuses[-1] == "completed"
+    assert all(p["type"] == "sidecar_migration_progress" for p in recorder.payloads)
+
+    # Scanner cache was reconciled to the mirror preview and persisted.
+    entry = use_case._test_scanner._cache.raw_data[0]
+    assert entry["preview_url"] == _normalize(mirror / "model.preview.webp")
+    assert use_case._test_scanner.persist_calls == 1
+
+
+@pytest.mark.asyncio
+async def test_migrate_to_alongside_reverses_layout(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("alongside")
+    model = _write_model(library_root / "sub", "model")
+    mirror = _mirror_dir(library_root, sidecar_root, "sub")
+    sidecar = _write_sidecar(mirror, "model", model)
+    preview = mirror / "model.preview.webp"
+    preview.write_bytes(b"preview")
+
+    use_case = _make_use_case([str(model)])
+    summary = await use_case.migrate_to_alongside(force=True)
+
+    assert summary["success"] is True
+    assert summary["moved"] == 2
+
+    assert not sidecar.exists()
+    assert not preview.exists()
+    moved_sidecar = library_root / "sub" / "model.metadata.json"
+    assert moved_sidecar.exists()
+    assert (library_root / "sub" / "model.preview.webp").exists()
+
+    metadata = json.loads(moved_sidecar.read_text(encoding="utf-8"))
+    assert metadata["file_path"] == _normalize(model)
+    assert metadata["preview_url"] == _normalize(
+        library_root / "sub" / "model.preview.webp"
+    )
+
+    entry = use_case._test_scanner._cache.raw_data[0]
+    assert entry["preview_url"] == _normalize(
+        library_root / "sub" / "model.preview.webp"
+    )
+    assert use_case._test_scanner.persist_calls == 1
+
+
+@pytest.mark.asyncio
+async def test_migrate_conflict_keeps_newer_file(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("centralized")
+    mirror = _mirror_dir(library_root, sidecar_root)
+
+    # Model A: destination (mirror) sidecar is newer -> destination wins.
+    model_a = _write_model(library_root, "model_a")
+    src_a = _write_sidecar(library_root, "model_a", model_a, preview_ext=None)
+    dst_a = _write_sidecar(mirror, "model_a", model_a, preview_ext=None)
+    os.utime(src_a, (1000, 1000))
+    os.utime(dst_a, (2000, 2000))
+
+    # Model B: source (alongside) sidecar is newer -> source replaces.
+    model_b = _write_model(library_root, "model_b")
+    src_b = _write_sidecar(library_root, "model_b", model_b, preview_ext=None)
+    dst_b = _write_sidecar(mirror, "model_b", model_b, preview_ext=None)
+    (mirror / "model_b.metadata.json").write_text(
+        json.dumps({"stale": True}), encoding="utf-8"
+    )
+    os.utime(src_b, (3000, 3000))
+    os.utime(dst_b, (2000, 2000))
+
+    use_case = _make_use_case([str(model_a), str(model_b)])
+    summary = await use_case.migrate_to_centralized(force=True)
+
+    assert summary["conflicts"] == 2
+    assert summary["moved"] == 1
+
+    # A: destination kept, source deleted, content untouched.
+    assert not src_a.exists()
+    metadata_a = json.loads(dst_a.read_text(encoding="utf-8"))
+    assert metadata_a["file_name"] == "model_a"
+
+    # B: newer source replaced the stale destination.
+    assert not src_b.exists()
+    metadata_b = json.loads(dst_b.read_text(encoding="utf-8"))
+    assert metadata_b.get("stale") is None
+    assert metadata_b["file_name"] == "model_b"
+
+
+@pytest.mark.asyncio
+async def test_migrate_missing_model_file_is_skipped(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("centralized")
+    missing_model = library_root / "ghost.safetensors"
+    sidecar = _write_sidecar(library_root, "ghost", missing_model, preview_ext=None)
+
+    use_case = _make_use_case([str(missing_model)])
+    summary = await use_case.migrate_to_centralized(force=True)
+
+    assert summary["success"] is True
+    assert summary["skipped"] == 1
+    assert summary["moved"] == 0
+    # Sidecar stays put when the model file is gone.
+    assert sidecar.exists()
+
+
+@pytest.mark.asyncio
+async def test_migrate_empty_library_is_noop(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("centralized")
+    recorder = _ProgressRecorder()
+    use_case = _make_use_case([])
+
+    summary = await use_case.migrate_to_centralized(recorder, force=True)
+
+    assert summary["success"] is True
+    assert summary["models_total"] == 0
+    assert summary["moved"] == 0
+    statuses = [payload["status"] for payload in recorder.payloads]
+    assert statuses == ["started", "completed"]
+
+
+@pytest.mark.asyncio
+async def test_migrate_to_centralized_refuses_when_already_centralized(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("centralized")
+    use_case = _make_use_case([])
+
+    summary = await use_case.migrate_to_centralized()
+
+    assert summary["success"] is False
+    assert "already centralized" in summary["error"]
+    assert summary["moved"] == 0
+
+
+@pytest.mark.asyncio
+async def test_migrate_to_alongside_refuses_when_already_alongside(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("alongside")
+    use_case = _make_use_case([])
+
+    summary = await use_case.migrate_to_alongside()
+
+    assert summary["success"] is False
+    assert "already alongside" in summary["error"]
+    assert summary["moved"] == 0
+
+
+def _make_use_case_with_entries(entries: List[Dict[str, Any]]) -> SidecarMigrationUseCase:
+    scanner = _FakeScanner(entries)
+
+    async def scanner_factory() -> _FakeScanner:
+        return scanner
+
+    use_case = SidecarMigrationUseCase(
+        scanner_factories=(("lora", scanner_factory),),
+        settings_service=get_settings_manager(),
+    )
+    use_case._test_scanner = scanner
+    return use_case
+
+
+@pytest.mark.asyncio
+async def test_migrate_reconcile_clears_stale_preview_when_none_remains(
+    library_root: Path, sidecar_root: Path
+):
+    _set_mode("centralized")
+    model = _write_model(library_root, "model")
+    _write_sidecar(library_root, "model", model, preview_ext=None)
+
+    stale_url = _normalize(library_root / "model.preview.webp")
+    entries = [
+        {"file_path": str(model), "preview_url": stale_url, "preview_nsfw_level": 4}
+    ]
+    use_case = _make_use_case_with_entries(entries)
+    summary = await use_case.migrate_to_centralized(force=True)
+
+    assert summary["success"] is True
+    entry = use_case._test_scanner._cache.raw_data[0]
+    # No preview exists in either layout: the stale reference is cleared.
+    assert entry["preview_url"] == ""
+    assert use_case._test_scanner.persist_calls == 1
+
+
+@pytest.mark.asyncio
+async def test_migrate_reconcile_survives_per_model_errors(
+    library_root: Path, sidecar_root: Path, monkeypatch: pytest.MonkeyPatch
+):
+    _set_mode("centralized")
+    model_ok = _write_model(library_root, "ok")
+    _write_sidecar(library_root, "ok", model_ok)
+    (library_root / "ok.preview.webp").write_bytes(b"preview")
+    model_bad = _write_model(library_root, "bad")
+    _write_sidecar(library_root, "bad", model_bad, preview_ext=None)
+
+    use_case = _make_use_case([str(model_ok), str(model_bad)])
+    original = use_case._migrate_model
+
+    async def failing_migrate(model_path: str, **kwargs):
+        if os.path.basename(model_path) == "bad.safetensors":
+            raise RuntimeError("boom")
+        return await original(model_path, **kwargs)
+
+    monkeypatch.setattr(use_case, "_migrate_model", failing_migrate)
+    summary = await use_case.migrate_to_centralized(force=True)
+
+    assert summary["success"] is False
+    assert summary["error_count"] == 1
+    # The healthy model's cache entry is still reconciled and persisted.
+    ok_entry = use_case._test_scanner._cache.raw_data[0]
+    assert ok_entry["preview_url"] == _normalize(
+        _mirror_dir(library_root, sidecar_root) / "ok.preview.webp"
+    )
+    assert use_case._test_scanner.persist_calls == 1
+
+
+@pytest.mark.asyncio
+async def test_migrate_covers_mixed_case_and_example_previews(
+    library_root: Path, sidecar_root: Path
+):
+    """Previews like model.WEBP / model.example.0.jpeg migrate too (#225 compat)."""
+
+    _set_mode("centralized")
+    model = _write_model(library_root, "model")
+    _write_sidecar(library_root, "model", model, preview_ext=".preview.WEBP")
+    (library_root / "model.preview.WEBP").write_bytes(b"preview")
+    (library_root / "model.example.0.jpeg").write_bytes(b"example")
+
+    use_case = _make_use_case([str(model)])
+    summary = await use_case.migrate_to_centralized(force=True)
+
+    assert summary["success"] is True
+    assert summary["moved"] == 3  # sidecar + 2 previews
+
+    mirror = _mirror_dir(library_root, sidecar_root)
+    assert (mirror / "model.preview.WEBP").exists()
+    assert (mirror / "model.example.0.jpeg").exists()
+    assert not (library_root / "model.preview.WEBP").exists()
+    assert not (library_root / "model.example.0.jpeg").exists()
+
+    metadata = json.loads((mirror / "model.metadata.json").read_text(encoding="utf-8"))
+    assert metadata["preview_url"] == _normalize(mirror / "model.preview.WEBP")
+
+
+@pytest.mark.asyncio
+async def test_migrate_root_relocates_tree_and_reconciles(
+    library_root: Path, sidecar_root: Path, tmp_path: Path
+):
+    _set_mode("centralized")
+    library = get_settings_manager().get_active_library_name()
+    component = root_mirror_component(str(library_root))
+
+    # Assets under the OLD root, mirroring the layout.
+    old_root = tmp_path / "old_sidecars"
+    old_mirror = old_root / library / component / "sub"
+    old_mirror.mkdir(parents=True)
+    model = _write_model(library_root / "sub", "model")
+    payload = {
+        "file_name": "model",
+        "file_path": _normalize(model),
+        "preview_url": _normalize(old_mirror / "model.preview.png"),
+    }
+    (old_mirror / "model.metadata.json").write_text(json.dumps(payload), encoding="utf-8")
+    (old_mirror / "model.preview.png").write_bytes(b"preview")
+
+    entries = [
+        {
+            "file_path": str(model),
+            "preview_url": _normalize(old_mirror / "model.preview.png"),
+            "preview_nsfw_level": 2,
+        }
+    ]
+    use_case = _make_use_case_with_entries(entries)
+    summary = await use_case.migrate_root(str(old_root), force=True)
+
+    assert summary["success"] is True
+    assert summary["moved"] == 2
+
+    new_mirror = sidecar_root / library / component / "sub"
+    assert (new_mirror / "model.metadata.json").exists()
+    assert (new_mirror / "model.preview.png").exists()
+
+    # Sidecar preview_url rewritten onto the new root.
+    migrated = json.loads((new_mirror / "model.metadata.json").read_text(encoding="utf-8"))
+    assert migrated["preview_url"] == _normalize(new_mirror / "model.preview.png")
+    # Model path fields untouched — model files never move.
+    assert migrated["file_path"] == _normalize(model)
+
+    # Scanner cache preview URLs repointed and persisted.
+    entry = use_case._test_scanner._cache.raw_data[0]
+    assert entry["preview_url"] == _normalize(new_mirror / "model.preview.png")
+    assert use_case._test_scanner.persist_calls == 1
+
+    # Emptied old tree pruned.
+    assert not old_root.exists()
+
+
+@pytest.mark.asyncio
+async def test_migrate_root_guards(
+    library_root: Path, sidecar_root: Path, tmp_path: Path
+):
+    _set_mode("centralized")
+    use_case = _make_use_case([])
+
+    summary = await use_case.migrate_root("")
+    assert summary["success"] is False
+    assert "old_root is required" in summary["error"]
+
+    summary = await use_case.migrate_root(str(sidecar_root))
+    assert summary["success"] is False
+    assert "matches the configured" in summary["error"]
+
+    _set_mode("alongside")
+    summary = await use_case.migrate_root(str(tmp_path / "old_sidecars"))
+    assert summary["success"] is False
+    assert "not centralized" in summary["error"]
+
+
+@pytest.mark.asyncio
+async def test_migrate_root_missing_old_tree_is_noop(
+    library_root: Path, sidecar_root: Path, tmp_path: Path
+):
+    _set_mode("centralized")
+    use_case = _make_use_case([])
+
+    summary = await use_case.migrate_root(str(tmp_path / "nonexistent"), force=True)
+
+    assert summary["success"] is True
+    assert summary["moved"] == 0

tests/utils/test_sidecar_paths.py

@@ -0,0 +1,285 @@
+"""Tests for py.utils.sidecar_paths (alongside + centralized storage modes)."""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+import pytest
+
+from py.services.settings_manager import get_settings_manager
+from py.utils import sidecar_paths
+from py.utils.sidecar_paths import (
+    METADATA_SUFFIX,
+    get_configured_sidecar_root,
+    get_metadata_path,
+    get_preview_dir,
+    get_sidecar_dir,
+    get_sidecar_root,
+    get_storage_mode,
+    is_centralized,
+    is_metadata_path,
+    resolve_centralized_dir,
+    resolve_centralized_dir_for_dir,
+    resolve_metadata_path,
+    root_mirror_component,
+    sanitize_path_component,
+)
+
+
+def _normalize(path: Path) -> str:
+    return str(path).replace(os.sep, "/")
+
+
+@pytest.fixture
+def model_roots(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> dict:
+    """Point every config model root the sidecar module reads at tmp_path."""
+
+    from py.config import config
+
+    loras = tmp_path / "loras"
+    checkpoints = tmp_path / "checkpoints"
+    loras.mkdir()
+    checkpoints.mkdir()
+
+    for attr, value in (
+        ("loras_roots", [str(loras)]),
+        ("base_models_roots", [str(checkpoints)]),
+        ("embeddings_roots", []),
+        ("other_roots", []),
+        ("extra_loras_roots", []),
+        ("extra_checkpoints_roots", []),
+        ("extra_unet_roots", []),
+        ("extra_embeddings_roots", []),
+    ):
+        monkeypatch.setattr(config, attr, value, raising=False)
+
+    return {"loras": loras, "checkpoints": checkpoints}
+
+
+@pytest.fixture
+def centralized(model_roots: dict, tmp_path: Path) -> Path:
+    """Enable centralized mode rooted at tmp_path/sidecars; returns the root."""
+
+    sidecar_root = tmp_path / "sidecars"
+    settings = get_settings_manager()
+    settings.set("sidecar_storage_mode", "centralized")
+    settings.set("sidecar_storage_path", str(sidecar_root))
+    return sidecar_root
+
+
+class TestAlongsideMode:
+    def test_default_mode_is_alongside(self):
+        assert get_storage_mode() == "alongside"
+        assert not is_centralized()
+        assert get_sidecar_root() == ""
+
+    def test_metadata_path_next_to_model(self, tmp_path: Path):
+        model = tmp_path / "sub" / "model.safetensors"
+        assert get_metadata_path(str(model)) == os.path.join(
+            str(tmp_path), "sub", "model" + METADATA_SUFFIX
+        )
+
+    def test_preview_and_sidecar_dir_are_model_dir(self, tmp_path: Path):
+        model = tmp_path / "sub" / "model.safetensors"
+        expected = os.path.dirname(os.path.abspath(str(model)))
+        assert get_sidecar_dir(str(model)) == expected
+        assert get_preview_dir(str(model)) == expected
+
+
+class TestPathPredicates:
+    def test_is_metadata_path(self):
+        assert is_metadata_path("/x/model.metadata.json")
+        assert not is_metadata_path("/x/model.safetensors")
+        assert not is_metadata_path("/x/model.metadata.json.bak")
+
+    def test_resolve_metadata_path_passthrough_for_sidecar(self):
+        sidecar = "/x/model.metadata.json"
+        assert resolve_metadata_path(sidecar) == sidecar
+
+    def test_resolve_metadata_path_derives_for_model(self, tmp_path: Path):
+        model = tmp_path / "model.safetensors"
+        assert resolve_metadata_path(str(model)) == get_metadata_path(str(model))
+
+
+class TestSanitizePathComponent:
+    def test_special_characters_replaced(self):
+        assert sanitize_path_component("foo bar/baz:qux") == "foo_bar_baz_qux"
+
+    def test_safe_characters_kept(self):
+        assert sanitize_path_component("Flux-1.dev_v2") == "Flux-1.dev_v2"
+
+    def test_empty_falls_back_to_underscore(self):
+        assert sanitize_path_component("") == "_"
+        assert sanitize_path_component(None) == "_"
+
+
+class TestCentralizedMode:
+    def test_mirror_layout(self, model_roots: dict, centralized: Path):
+        model = model_roots["loras"] / "styles" / "anime" / "model.safetensors"
+        library = get_settings_manager().get_active_library_name()
+        root_component = root_mirror_component(str(model_roots["loras"]))
+
+        metadata_path = get_metadata_path(str(model))
+
+        expected = os.path.join(
+            str(centralized), library, root_component, "styles", "anime", "model" + METADATA_SUFFIX
+        )
+        assert metadata_path == expected
+        assert get_preview_dir(str(model)) == os.path.dirname(expected)
+        assert is_centralized()
+
+    def test_same_basename_roots_get_distinct_mirrors(
+        self, model_roots: dict, centralized: Path, tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+    ):
+        from py.config import config
+
+        # Two roots sharing the basename "loras" must not share a mirror dir.
+        other_parent = tmp_path / "elsewhere"
+        other_root = other_parent / "loras"
+        other_root.mkdir(parents=True)
+        monkeypatch.setattr(
+            config,
+            "loras_roots",
+            [str(model_roots["loras"]), str(other_root)],
+            raising=False,
+        )
+
+        model_a = model_roots["loras"] / "model.safetensors"
+        model_b = other_root / "model.safetensors"
+
+        dir_a = resolve_centralized_dir(str(model_a))
+        dir_b = resolve_centralized_dir(str(model_b))
+        assert dir_a is not None and dir_b is not None
+        assert dir_a != dir_b
+        assert root_mirror_component(str(model_roots["loras"])) != root_mirror_component(
+            str(other_root)
+        )
+        # Same root always maps to the same component (stable hash).
+        assert root_mirror_component(str(model_roots["loras"])) == root_mirror_component(
+            str(model_roots["loras"]) + os.sep
+        )
+
+    def test_longest_root_wins(self, model_roots: dict, centralized: Path, monkeypatch: pytest.MonkeyPatch):
+        from py.config import config
+
+        nested = model_roots["loras"] / "nested"
+        nested.mkdir()
+        monkeypatch.setattr(
+            config,
+            "loras_roots",
+            [str(model_roots["loras"]), str(nested)],
+            raising=False,
+        )
+        library = get_settings_manager().get_active_library_name()
+
+        model = nested / "model.safetensors"
+        assert get_metadata_path(str(model)) == os.path.join(
+            str(centralized), library, root_mirror_component(str(nested)), "model" + METADATA_SUFFIX
+        )
+
+    def test_outside_roots_falls_back_to_alongside(
+        self, model_roots: dict, centralized: Path, tmp_path: Path
+    ):
+        outside = tmp_path / "elsewhere" / "model.safetensors"
+
+        assert resolve_centralized_dir(str(outside)) is None
+        assert get_sidecar_dir(str(outside)) == os.path.dirname(
+            os.path.abspath(str(outside))
+        )
+        assert get_metadata_path(str(outside)) == os.path.join(
+            str(tmp_path), "elsewhere", "model" + METADATA_SUFFIX
+        )
+
+    def test_resolve_centralized_dir_for_dir_matches_model_resolution(
+        self, model_roots: dict, centralized: Path
+    ):
+        model_dir = model_roots["checkpoints"] / "sub"
+        model = model_dir / "model.safetensors"
+
+        assert resolve_centralized_dir_for_dir(str(model_dir)) == resolve_centralized_dir(
+            str(model)
+        )
+
+    def test_resolve_centralized_dir_for_dir_root_maps_to_mirror_base(
+        self, model_roots: dict, centralized: Path
+    ):
+        library = get_settings_manager().get_active_library_name()
+
+        assert resolve_centralized_dir_for_dir(str(model_roots["loras"])) == os.path.join(
+            str(centralized), library, root_mirror_component(str(model_roots["loras"]))
+        )
+
+    def test_empty_path_uses_default_sidecar_root(self, model_roots: dict, tmp_path: Path):
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_mode", "centralized")
+        settings.set("sidecar_storage_path", "")
+
+        root = get_sidecar_root()
+        assert root
+        assert root.endswith(os.sep + "sidecars")
+        assert is_centralized()
+
+
+class TestModeIndependentResolution:
+    """Migration tooling resolves the mirror layout regardless of active mode."""
+
+    def test_configured_root_resolves_in_alongside_mode(self, tmp_path: Path):
+        sidecar_root = tmp_path / "sidecars"
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_mode", "alongside")
+        settings.set("sidecar_storage_path", str(sidecar_root))
+
+        assert get_sidecar_root() == ""
+        assert get_configured_sidecar_root() == os.path.abspath(str(sidecar_root))
+
+    def test_configured_root_defaults_to_settings_dir(self):
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_mode", "alongside")
+        settings.set("sidecar_storage_path", "")
+
+        root = get_configured_sidecar_root()
+        assert root
+        assert root.endswith(os.sep + "sidecars")
+
+    def test_resolve_centralized_dir_for_dir_with_explicit_root(
+        self, model_roots: dict, tmp_path: Path
+    ):
+        sidecar_root = tmp_path / "sidecars"
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_mode", "alongside")
+        library = settings.get_active_library_name()
+
+        model_dir = model_roots["loras"] / "sub"
+
+        # Alongside mode: no root resolves without the override.
+        assert resolve_centralized_dir_for_dir(str(model_dir)) is None
+        assert resolve_centralized_dir_for_dir(
+            str(model_dir), sidecar_root=str(sidecar_root)
+        ) == os.path.join(
+            str(sidecar_root), library, root_mirror_component(str(model_roots["loras"])), "sub"
+        )
+
+
+class TestSettingsValidation:
+    def test_invalid_mode_falls_back_to_alongside(self):
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_mode", "bogus")
+        assert settings.get("sidecar_storage_mode") == "alongside"
+
+    def test_mode_is_normalized(self):
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_mode", " Centralized ")
+        assert settings.get("sidecar_storage_mode") == "centralized"
+
+    def test_path_is_normalized_to_absolute(self, tmp_path: Path):
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_path", str(tmp_path / "sidecars"))
+        assert settings.get("sidecar_storage_path") == os.path.abspath(
+            str(tmp_path / "sidecars")
+        )
+
+    def test_non_string_path_becomes_empty(self):
+        settings = get_settings_manager()
+        settings.set("sidecar_storage_path", None)
+        assert settings.get("sidecar_storage_path") == ""