fix(download): allow downloading additional files of an in-library model version (#1058)

docs/plans/issue-1058-multi-file-version-downloads.md

@@ -0,0 +1,206 @@
+# Plan: Multi-File Downloads Within a Single CivitAI Model Version
+
+**Issue:** [#1058 — Cannot download multiple file variants from the same model version](https://github.com/willmiao/ComfyUI-Lora-Manager/issues/1058)
+**Status:** v2 — revised after adversarial review (backend correctness + frontend/tests)
+**Scope:** CivitAI/CivArchive downloads of `lora`, `checkpoint`, `embedding` model types. HuggingFace downloads are out of scope (already per-file).
+
+> v2 changelog: incorporated 18 review findings. Key changes vs v1:
+> shared file resolver + `resolved_version_id` for the gate (R1); `file_params` normalization at API boundary (R2); D2 hash-matching rule fixed for empty-hash cases (R6/R7); D3 extended to re-point `version_index` on removal (R4); D4 replaced with a child table (R3); `delete_model_version` interaction documented (R5); `ModelVersionsTab` surface added to phase 2 (F6); phase-2 multi-file loop requires a reload-deferred download variant (F7); queue-retry `file_params=NULL` known issue recorded (R9); test-fixture gaps and revised estimates (F10).
+
+---
+
+## 1. Problem Statement
+
+A CivitAI model version can contain multiple downloadable weight files (e.g. fp16/fp32, safetensors/ckpt, different sizes). LoRA Manager already has a working file-selection pipeline (frontend file dialog → `fileParams` → backend file matching), but downloaded state is tracked at the **model-version** level. After any single file of a version is downloaded:
+
+1. The version is marked **In Library** and the file-selection entry point disappears.
+2. The backend rejects further download attempts for that version.
+
+There is no way to download the remaining files of the same version through LoRA Manager.
+
+## 2. Current State (verified against code; all references confirmed by review)
+
+### 2.1 Download gating — backend (`py/services/download_manager.py`)
+
+`_execute_original_download` enforces two version-level gates:
+
+- **Library gate, early** (lines 1157–1184, before metadata fetch, fires when `model_version_id` given) and **late** (lines 1350–1376, fires only when `model_version_id is None`): `scanner.check_model_version_exists(version_id)` across lora/checkpoint/embedding scanners → hard error `"Model version already exists in ... library"`.
+- **History gate** (lines 1238–1279): when `skip_previously_downloaded_model_versions` setting is on, `_has_been_downloaded(model_type, version_id)` → silent skip. History DB primary key is `(model_type, version_id)` (`py/services/downloaded_version_history_service.py:61`).
+
+File selection works: `file_params {id, type, format, size, fp}` is matched against `version_info.files` (lines 1498–1569), **but only under `if file_params and model_version_id:` (line 1499)** — with `model_id`-only requests the selection silently falls back to the primary file (1571–1619). `file_params` currently carries no file `name` or hash.
+
+### 2.2 Downloaded-state surfacing — backend (`py/routes/handlers/model_handlers.py`)
+
+`get_civitai_versions` (lines 2148–2188) sets per-version `existsLocally` via `cache.version_index.get(version_id)` (plus a single `localPath` from that entry) and `hasBeenDownloaded` via the history service. No per-file granularity.
+
+### 2.3 Frontend blockers (`static/js/managers/DownloadManager.js`)
+
+Three independent gates prevent re-entering the file dialog:
+
+1. **Line 598:** file-select badge rendered only when `modelFiles.length > 1 && !existsLocally`.
+2. **Lines 666–681 (`updateNextButtonState`):** Next button disabled with "Already in Library" when `currentVersion.existsLocally`.
+3. **Lines 784–787 (`proceedToLocation`):** toast + abort when `currentVersion.existsLocally`.
+
+The badge path (`confirmFileSelection` lines 737–759 → `proceedToLocationContent` → `startDownload` single mode → `executeDownloadWithProgress` → POST `file_params`, `static/js/api/baseModelApi.js:1236–1250`) has **zero** `existsLocally` guards (all 12 occurrences enumerated; none on this path; `import/DownloadManager.js` has none either). The `.exists-locally` CSS class is purely visual (`download-modal.css:496–499`). **Making the badge visible again is sufficient to unlock the flow** for phase 1.
+
+Post-download refresh is clean: the modal closes and `resetAndReload(true)` performs a full library refetch (`DownloadManager.js:1063`); dialog reopen resets state and refetches versions with no client-side cache. No same-session staleness.
+
+### 2.4 Local identity of the downloaded file
+
+`LoraMetadata/CheckpointMetadata/EmbeddingMetadata.from_civitai_info(version_info, file_info, ...)` (`py/utils/models.py:245–369`) persists:
+
+- `sha256` = `file_info.hashes.SHA256` (lowercased, defaults to `""`) — a stable per-file identity;
+- `civitai` = the full `version_info` payload (including the `files` list).
+
+Metadata refresh (`metadata_sync_service.py:104–105`) replaces the `civitai` blob wholesale but never overwrites top-level `sha256`; `verify_duplicate_hashes` (481–526) corrects it to the on-disk hash. Top-level-sha256 matching is refresh-robust.
+
+**Caveats (review R6/R7):**
+- SHA256 is not guaranteed: CivArchive's transform only sets `hashes` when source data carries it (`civarchive_client.py:185–189`); `from_civitai_info` defaults to `""`.
+- Name fallback is unreliable exactly when it matters: local `file_name` is extension-less (`models.py:264`) and `generate_unique_filename` rewrites it with a hash suffix on conflict (`download_manager.py:1125–1136`); checkpoints with `hash_status='pending'` keep empty sha256 until on-demand hashing (`model_scanner.py:1232–1240`).
+
+### 2.5 Version index collision (pre-existing hazard)
+
+`ModelCache.version_index` is single-valued (`model_cache.py:133`: `version_index[version_id] = item`). Two files of the same version in the library → second entry overwrites the first; `remove_from_version_index` (lines 151–181) drops the whole version key when the indexed entry is removed, even if a sibling file remains. ~10 read sites depend on this index (48 grep touch points total; readers include `recipe_scanner.py:2682–2726`, `recipe_format.py:37–40`, `misc_handlers.py:2440–2444`, `model_handlers.py`, `model_scanner.check_model_version_exists:2444`).
+
+Review correction (F3): bulk paths `remove_models` (`model_scanner.py:2376`) and `update_single_model_cache` (`:1689`) call `rebuild_version_index()` right after, so a sibling re-enters the index in those flows — the hazard is narrower than v1 stated, but direct `remove_from_version_index` callers (e.g. `model_scanner.py:1018`) still drop the key, and the user-visible artifact in phase 1 is real: `localPath` in the dialog flips to whichever file was indexed last.
+
+### 2.6 Entry points that send / don't send `file_params` (fully enumerated by review)
+
+**Send `file_params` (user-initiated dialog flows only):** `DownloadManager.js:1611–1639` (single mode). API surface accepting arbitrary JSON `file_params`: GET `/api/lm/download-model-get` (`model_handlers.py:1634–1686`), POST `/api/lm/downloads/queue/add` (`model_handlers.py:1799–1832`).
+
+**Never send `file_params` (keep version-level semantics):** batch download (`DownloadManager.js:1756–1766`; batch also filters out in-library versions at `:1648`), `downloadVersionWithDefaults` (`:1810–1830`), recipe import (`import/DownloadManager.js:269–276`), bulk missing-LoRA (`BulkMissingLoraDownloadManager.js:292–299`), `RecipeModal.js:1728–1736`, `ModelVersionsTab.js:1427`. `web/comfyui/` and `vue-widgets/src` contain **no** download triggers at all (grep-verified). `py/services/use_cases/` has only `download_model_use_case.py` (pass-through).
+
+### 2.7 Paths that do NOT need changes (verified)
+
+- **aria2 pause/resume** (`_resume_restored_aria2_download`, line 754+): resumes from persisted `resume_context`; never re-runs existence gates.
+- **`download_coordinator.py:90`**: pure pass-through of `file_params`.
+- **Update checker / plugin self-update** (`update_routes.py:496–501`): only closes the history DB handle.
+- **History delete semantics**: `mark_as_deleted` sets `is_deleted_override=1` and `has_been_downloaded` then returns False (`downloaded_version_history_service.py:276`) — LM-initiated deletes already reset the history skip.
+
+### 2.8 Related pre-existing issues (record, not necessarily fix)
+
+- **Queue retry drops file selection** (R9): `download_queue_service.retry_from_history` / `retry_all_failed` re-queue with `file_params=NULL` (`download_queue_service.py:705, 758`) although the queue table has a `file_params` column (`:43`) — a retried non-primary download silently reverts to the primary file. Fix alongside phase 1 (small: persist and reuse the column).
+- **`delete_model_version`** (`misc_handlers.py:2410–2487`): resolves the file via the single-valued `version_index` (2440–2444), deletes only that one file, and `mark_as_deleted` flags the **entire version** as deleted in history (2479) even when a sibling file remains in the library. See phase 2 item 6.1.5.
+
+## 3. Goals / Non-Goals
+
+**Goals**
+
+- G1: A user can download any not-yet-downloaded file of a version already partially in the library (issue repro steps 6–8).
+- G2: True duplicates stay blocked: downloading the *same* file of the same version twice is rejected.
+- G3: Per-file downloaded state visible in the file dialog; multiple files selectable and downloadable in one pass.
+- G4: No regression for version-level semantics relied on by batch download, recipe missing-LoRA detection, and `skip_previously_downloaded_model_versions`.
+
+**Non-Goals**
+
+- No change to recipe `inLibrary` semantics ("any file of the version present" remains sufficient).
+- No change to the update-checker (version-level comparison).
+- No primary-key rebuild of the history database.
+- HuggingFace download flow untouched.
+
+## 4. Design Decisions
+
+- **D1 — Explicit file selection bypasses the history gate, version-level gates stay for everyone else.** The history skip exists to dedupe automated flows. A user explicitly picking a file is unambiguous intent; the file-level library gate (G2) still prevents real duplicates. **Guard conditions use normalized truthiness** (see D1a). All confirmed `file_params` senders are user-initiated dialog flows (2.6), and LM-initiated deletes already reset history (2.7), so the bypass only affects "downloaded but not LM-deleted" versions with the setting on — intended.
+- **D1a — `file_params` normalization at the boundary (R2).** `download-model-get` and `downloads/queue/add` accept arbitrary JSON; `{}` is `not None` but falsy and would bypass gates while downloading the primary file. Normalize `file_params = file_params or None` in the coordinator/handlers, and treat the bypass as active only when a target file id is resolvable.
+- **D2 — File identity matching rule (R6/R7):** hash-compare **only when both sides are non-empty** (lowercase SHA256 equality); name-compare when either side is empty. Never let `"" == ""` match. Name fallback caveats from 2.4 apply (renamed files, pending checkpoint hashes) — acceptable residual risk, worst case is a blocked re-download the user can retry after hashing completes.
+- **D3 — Cache indexes: additive multi-index + removal re-pointing (R4).** Add `version_files_index: Dict[int, List[dict]]` maintained alongside `version_index` by the same add/remove/rebuild methods; existing readers of `version_index` untouched. Additionally fix `remove_from_version_index`: when the popped entry has a surviving sibling (per the multi-index), re-point `version_index[version_id]` to the sibling instead of dropping the key; same for the `model_id_index` descriptor. This closes the 2.5 hazard for existing readers (`check_model_version_exists`, `existsLocally`, recipe matching) without restructuring anything.
+- **D4 — Per-file history via a child table (R3).** v1's additive-column approach is structurally impossible on a `(model_type, version_id)` PK (`ON CONFLICT DO UPDATE` would keep only the last file). Instead add `downloaded_version_files(model_type, version_id, file_id, file_name, downloaded_at, PRIMARY KEY(model_type, version_id, file_id))` — additive, no PK rebuild, honors the Non-Goal. Existing version-level table and queries unchanged. New per-file queries are opt-in. `_initialize_schema` uses `CREATE TABLE IF NOT EXISTS`, so the new table is created for existing DBs without any ALTER.
+- **D5 — UI flow reuse, with an extracted inner download function for multi-file (F7).** Phase 1 unlocks the existing badge → file dialog → location → download pipeline. Phase 2 upgrades the dialog to multi-select; iterating `executeDownloadWithProgress` as-is would produce N full library reloads, N toasts, and competing failure-summary modals — so phase 2 extracts a reload-deferred, failure-aggregating inner variant and runs one reload + one summary at the end.
+
+## 5. Implementation — Phase 1 (fix the issue; independently shippable)
+
+### 5.1 Backend — `py/services/download_manager.py`
+
+1. **Normalize `file_params`** at the boundary (D1a): `download_coordinator.schedule_download` and the two API handlers (`model_handlers.py:1649–1666`, `1810–1832`) apply `file_params = file_params or None`.
+2. **Extract a shared file resolver** (R1): pull the matching logic at 1498–1569 into `_resolve_target_file(version_info, file_params) -> Optional[dict]`, used by **both** the new gate and the download-selection path. The selection path's condition (line 1499) switches from `model_version_id` to `resolved_version_id` (already computed at 1230–1236 from `version_info.id`), so gate and download always agree on the target file — including the `model_id`-only case.
+3. **New helper** `_find_local_file_entry(version_id, target_file) -> Optional[dict]`: iterate the three scanners' cached `raw_data` (NOT `version_index` — single-valued); candidates = entries whose `civitai.id` normalizes to `version_id`; match per D2.
+4. **Gate restructure in `_execute_original_download`**:
+   - Early scanner gate (1157–1184): add `file_params is None` guard; with normalized `file_params`, defer (file identity not resolvable before metadata fetch).
+   - After `version_info` fetch + `resolved_version_id` (~1229): when `file_params` present, resolve target file via the shared resolver; unresolvable → hard error "No matching file" (fail closed, prevents empty-dict bypass). Resolvable → `_find_local_file_entry`; hit → same hard error shape as today with the file name in the message.
+   - History gate (1238–1279): add `file_params is None` (D1). Base-model skip (1281–1324) unchanged — still applies.
+   - Late gate (1350–1376): add `file_params is None` guard (F2) — the post-fetch file-level check above already covers this case.
+   - Nothing between the early gate and the post-fetch point assumes the version is absent (review task 6: only provider selection + metadata fetch; no DB writes; `_persist_aria2_state` runs only when actually downloading at 1659).
+5. **Queue retry fix** (2.8, small): persist `file_params` into the queue table on enqueue and reuse it in `retry_from_history` / `retry_all_failed`.
+6. Logging: `[download]` lines for file-level allow/block, consistent with existing style.
+
+**Estimated:** ~150–220 LOC + resolver extraction.
+
+### 5.2 Frontend — `static/js/managers/DownloadManager.js`
+
+1. Line 598: drop `&& !existsLocally` from the badge condition (badge shows whenever `modelFiles.length > 1`).
+2. `fileParams` construction (1611–1616): add `name: this.selectedFile.name`.
+3. Surface the backend "file already in library" hard error as a toast instead of only the batch-summary modal (R10/F12 nit; reuse existing error message field).
+4. No changes to `updateNextButtonState` / `proceedToLocation` in phase 1; no template or CSS changes.
+
+**Known phase-1 UX limitations (acknowledged, fixed in phase 2):** with all files downloaded the badge still renders and re-picking a downloaded file fails late (backend error after the location step); `localPath` may point at a sibling file; batch-preview "In Library" badge stays version-level and gives no hint of remaining files.
+
+**Estimated:** ~10–30 LOC (confirmed realistic by review).
+
+### 5.3 Phase 1 tests
+
+Backend — extend `tests/services/test_download_manager_basic.py` (1694 lines; all fixture patterns exist):
+
+- **Fixture gaps to add (F10):** `DummyScanner.get_cached_data()`/`raw_data` stub (~10 lines); `hashes.SHA256` in the metadata-provider payload's `files`.
+- Cases: same version + different SHA256 in library + `file_params` → proceeds; same SHA256 → hard error; `file_params=None` + version in library → hard error (unchanged); history-skip on + `file_params` → not skipped; without → skipped (unchanged); empty-dict `file_params` normalized → version-level behavior; `model_id`-only + `file_params` → gate and selection resolve the same file; legacy metadata (empty local sha256) matched by name; target file with empty SHA256 → name fallback, no `""==""` false positive.
+- Queue retry: `file_params` survives retry.
+- Assert proceed/abort via the existing `_execute_download` mock pattern.
+
+Frontend (`tests/frontend/`): badge renders for multi-file version with `existsLocally=true` (pattern from `downloadManager.history.test.js`).
+
+**Estimated:** ~150–250 LOC (confirmed realistic).
+
+## 6. Implementation — Phase 2 (per-file status + multi-select + index hardening)
+
+### 6.1 Backend
+
+1. **`py/services/model_cache.py`** (D3): add `version_files_index`; maintain in `add_to_version_index` / `remove_from_version_index` / `rebuild_version_index`; removal re-points `version_index[version_id]` (and the `model_id_index` descriptor) to a surviving sibling instead of dropping the key.
+2. **`py/services/model_scanner.py`**: expose `get_files_for_version(version_id) -> List[dict]`.
+3. **`py/routes/handlers/model_handlers.py` `get_civitai_versions`**: annotate each version with `downloadedFiles: [{fileId, fileName, filePath}]` via `version_files_index` + D2 matching against `version.files`.
+4. **`py/services/downloaded_version_history_service.py`** (D4): new child table `downloaded_version_files`; `mark_downloaded` also upserts the child row when `file_id` known; `mark_as_deleted` clears the version's child rows only when no sibling remains in the library; new `get_downloaded_file_ids(model_type, version_id) -> set[int]`. `_record_downloaded_version_history` passes `file_info` through.
+5. **`delete_model_version`** (`misc_handlers.py:2410–2487`, R5): resolve **all** local files of the version via `version_files_index`; delete all (current endpoint semantics are version-level) or — if kept per-file — only `mark_as_deleted` when no sibling remains. Decide at implementation time; minimum is documenting current behavior.
+6. **`ModelVersionsTab` backend support**: none needed beyond item 3 (`downloadedFiles`); the tab consumes the same versions payload.
+
+### 6.2 Frontend
+
+1. **File dialog multi-select** — change surface (F8): option markup (`DownloadManager.js:712–724`), the single-select click handler (`727–734`), the `input[type="radio"]:checked` selector in `confirmFileSelection` (`738`); template `templates/components/modals/download_modal.html:48–60` (confirm-button label only); CSS `download-modal.css` — checkbox variant of `.file-option-radio input` (595–604) and a **new** `.file-option.disabled` style (does not exist). Files whose id ∈ `downloadedFiles` render disabled with an "In Library" tag.
+2. **Mixed-type guard (F8):** multi-select is restricted to files sharing the same routing target (`_isDiffusionModel` is computed once from a single `selectedFile` at 798–803; e.g. "Model" + "UNet" files route to different roots). Disallow mixed-type multi-select (simplest, predictable); single-file selection unchanged.
+3. **Multi-file download loop (D5/F7):** extract from `executeDownloadWithProgress` a reload-deferred, no-toast inner function; iterate per selected file with per-file progress; one `resetAndReload(true)` + one aggregated success/failure summary at the end (reuse `showDownloadBatchSummary`).
+4. **`updateNextButtonState` / `proceedToLocation`:** for multi-file versions, Next routes into the file dialog; hard block only when *every* weight file is downloaded.
+5. **`ModelVersionsTab.js` (F6):** the Download action (`:576` hidden when `isInLibrary`) — for multi-file versions with remaining files, show it and route into the download modal's file dialog; keep hidden when all files present.
+6. **Batch preview (F5):** `batch-preview-local-badge` (`:1320`) gains a "partially downloaded" hint for multi-file versions with remaining files.
+7. New i18n keys (`modals.download.fileSelection.inLibrary`, `downloadSelected`, partial-download tooltip, etc.) → run `python scripts/sync_translation_keys.py`.
+
+### 6.3 Phase 2 tests
+
+- `model_cache` (`tests/services/test_model_cache.py` already covers add/remove at 44–55): multi-valued index; sibling re-point on removal; rebuild.
+- `get_civitai_versions`: `downloadedFiles` correctness (hash match, name fallback, no match, CivArchive no-hash payload).
+- History service (`tests/services/test_downloaded_version_history_service.py` uses real SQLite on tmp_path): child-table creation on a legacy DB; per-file record/query; `mark_as_deleted` sibling semantics.
+- Frontend: dialog checkbox rendering/disabled state and multi-file confirm — **greenfield behavior coverage** (F10: no existing test exercises `showFileSelectionStep`/`confirmFileSelection`; infra exists, patterns must be built).
+
+## 7. Risks and Mitigations
+
+| Risk | Impact | Mitigation |
+|---|---|---|
+| History-gate bypass (D1) causes unwanted re-downloads in automated flows | Large checkpoint files re-downloaded | Bypass only with normalized, resolvable `file_params` (D1a); all such senders are user-initiated dialog flows (2.6, verified); tests pin batch/recipe/bulk behavior. |
+| Empty-hash matching edge cases (R6) | Duplicate download of the same file, or false block | D2 rule: hash only when both non-empty; name otherwise; never `""==""`. Residual risk documented (2.4). |
+| Phase-1 late-failure UX (F12) | User picks a downloaded file, fails only after location step | Toast surfacing (5.2.3); phase 2 disables downloaded files up front. |
+| Phase-2 index change corrupts existing behavior | Recipe matching, delete flows | Additive index + re-point only; `version_index` read semantics unchanged; `remove_models`/`update_single_model_cache` already rebuild (F3); tests. |
+| `delete_model_version` marks whole version deleted while sibling remains (R5) | History wrongly suppresses re-download of the surviving sibling's version | Phase 2 item 6.1.5; documented until then. |
+| History child-table migration failure on user installs | Service init crash | `CREATE TABLE IF NOT EXISTS` in `_initialize_schema`; failure degrades to version-level behavior (per-file queries return empty). |
+| Batch-preview badge misleading for partial versions (F5) | Minor UX confusion | Acknowledged in phase 1; fixed in phase 2 item 6.2.6. |
+| UI confusion: version shows "In Library" while files remain downloadable | Support burden | Phase 2: per-file disabled state + partial-download tooltip. |
+| Hash-identical sibling files (repacked content) | Second file blocked | Acceptable: scanner hash dedup already collapses them. |
+
+## 8. Rollout
+
+1. **Commit 1** — `fix(download): allow downloading additional files of an in-library model version (#1058)` → Phase 1 (5.1–5.3).
+2. **Commit 2** — `feat(download): per-file download status and multi-file selection (#1058)` → Phase 2 (6.1–6.3).
+
+Phase 1 alone resolves the issue as reported; phase 2 can ship in a later release if review prefers smaller increments.
+
+## 9. Effort Estimate (revised after review)
+
+| Phase | Backend | Frontend | Tests | Risk |
+|---|---|---|---|---|
+| 1 | ~150–220 LOC (+ queue-retry fix ~30) | ~10–30 LOC | ~150–250 LOC | Low |
+| 2 | ~250–350 LOC | ~250–350 LOC (multi-file loop refactor + ModelVersionsTab + batch badge) | ~250–350 LOC (dialog tests greenfield) | Medium |

py/routes/handlers/model_handlers.py

@@ -1659,7 +1659,8 @@ class ModelDownloadHandler:
                 import json
 
                 try:
-                    data["file_params"] = json.loads(file_params_json)
+                    # Normalize falsy payloads (e.g. {}) to None (#1058)
+                    data["file_params"] = json.loads(file_params_json) or None
                 except json.JSONDecodeError:
                     self._logger.warning(
                         "Invalid file_params JSON: %s", file_params_json
@@ -1811,7 +1812,8 @@ class ModelDownloadHandler:
 
             model_id = int(model_id_str) if model_id_str else None
             model_version_id = int(model_version_id_str) if model_version_id_str else None
-            file_params = json.loads(file_params_json) if file_params_json else None
+            # Normalize falsy payloads (e.g. {}) to None (#1058)
+            file_params = (json.loads(file_params_json) if file_params_json else None) or None
 
             service = await DownloadQueueService.get_instance()
             item = await service.add_to_queue(

py/services/download_coordinator.py

@@ -87,7 +87,9 @@ class DownloadCoordinator:
             progress_callback=progress_callback,
             download_id=download_id,
             source=payload.get("source"),
-            file_params=payload.get("file_params"),
+            # Normalize falsy file_params (e.g. {}) to None so download gates
+            # treat it as "no explicit file selection" (#1058).
+            file_params=payload.get("file_params") or None,
         )
 
         result["download_id"] = download_id

py/services/download_manager.py

@@ -213,6 +213,162 @@ class DownloadManager:
             )
             return False
 
+    async def _get_scanner_for_model_type(self, model_type: str):
+        """Return the scanner responsible for the given model type."""
+        if model_type == "checkpoint":
+            return await self._get_checkpoint_scanner()
+        if model_type == "embedding":
+            return await ServiceRegistry.get_embedding_scanner()
+        return await self._get_lora_scanner()
+
+    @staticmethod
+    def _resolve_target_file(
+        files: Any, file_params: Dict[str, Any] | None
+    ) -> Optional[Dict[str, Any]]:
+        """Resolve the target file within a version's file list from file_params.
+
+        Shared by the existence gate and the actual file selection so both
+        always agree on which file a download refers to (#1058). Returns None
+        when file_params is None or no file matches.
+        """
+        if not file_params or not isinstance(files, list):
+            return None
+
+        target_file_id = file_params.get("id")
+        target_type = file_params.get("type", "Model")
+        target_format = file_params.get("format")
+        target_size = file_params.get("size")
+        target_fp = file_params.get("fp")
+        is_primary = file_params.get("isPrimary", False)
+
+        logger.debug(
+            "[download] file_params received: id=%s, type=%s, format=%s, size=%s, fp=%s, "
+            "isPrimary=%s, total_files=%d",
+            target_file_id, target_type, target_format, target_size, target_fp,
+            is_primary, len(files),
+        )
+
+        file_info: Optional[Dict[str, Any]] = None
+
+        if target_file_id:
+            target_id_str = str(target_file_id)
+            for f in files:
+                if not isinstance(f, dict):
+                    continue
+                f_id = f.get("id")
+                if str(f_id) == target_id_str:
+                    file_info = f
+                    logger.debug(
+                        "[download] MATCH by ID: id=%s name='%s'",
+                        f_id, f.get("name"),
+                    )
+                    break
+            if not file_info:
+                logger.debug("[download] No file found with id=%s", target_file_id)
+
+        elif is_primary:
+            file_info = next(
+                (
+                    f
+                    for f in files
+                    if isinstance(f, dict)
+                    and f.get("primary")
+                    and f.get("type") in MODEL_WEIGHT_FILE_TYPES
+                ),
+                None,
+            )
+        else:
+            # Lenient metadata match: only compare fields present on both sides
+            for f in files:
+                if not isinstance(f, dict):
+                    continue
+                f_type = f.get("type", "")
+                if f_type != target_type:
+                    continue
+
+                f_meta = f.get("metadata", {})
+                f_format = f_meta.get("format") or f.get("format")
+                f_size = f_meta.get("size") or f.get("size")
+                f_fp = f_meta.get("fp") or f.get("fp")
+
+                if target_format and f_format != target_format:
+                    continue
+                if target_size and f_size and f_size != target_size:
+                    continue
+                if target_fp and f_fp and f_fp != target_fp:
+                    continue
+
+                file_info = f
+                break
+
+        return file_info
+
+    async def _find_local_file_entry(
+        self,
+        model_type: str,
+        model_version_id: int,
+        target_file: Dict[str, Any],
+    ) -> Optional[Dict[str, Any]]:
+        """Find a local library entry for a specific file of a model version.
+
+        Matches per design rule D2 (#1058): SHA256 is only compared when both
+        sides carry a non-empty hash; otherwise fall back to (extension-less)
+        file name equality. Never let two empty hashes compare equal.
+        """
+        try:
+            normalized_version_id = int(model_version_id)
+        except (TypeError, ValueError):
+            return None
+
+        try:
+            scanner = await self._get_scanner_for_model_type(model_type)
+            cache = await scanner.get_cached_data()
+        except Exception as exc:
+            logger.debug(
+                "Failed to scan local entries for version %s file check: %s",
+                model_version_id,
+                exc,
+            )
+            return None
+
+        raw_data = getattr(cache, "raw_data", None) if cache else None
+        if not raw_data:
+            return None
+
+        target_hash = str(
+            (target_file.get("hashes") or {}).get("SHA256") or ""
+        ).strip().lower()
+        target_name = str(target_file.get("name") or "").strip()
+        target_base = os.path.splitext(target_name)[0] if target_name else ""
+
+        for item in raw_data:
+            if not isinstance(item, dict):
+                continue
+            civitai_data = item.get("civitai")
+            if not isinstance(civitai_data, dict):
+                continue
+            try:
+                item_version_id = int(civitai_data.get("id"))
+            except (TypeError, ValueError):
+                continue
+            if item_version_id != normalized_version_id:
+                continue
+
+            local_hash = str(item.get("sha256") or "").strip().lower()
+            if target_hash and local_hash:
+                if local_hash == target_hash:
+                    return item
+                # Both sides carry hashes that differ: this is a different
+                # file of the same version — do not fall back to name match.
+                continue
+
+            if target_base:
+                local_name = str(item.get("file_name") or "").strip()
+                if local_name == target_base:
+                    return item
+
+        return None
+
     async def download_from_civitai(
         self,
         model_id: int | None = None,
@@ -242,6 +398,10 @@ class DownloadManager:
         Returns:
             Dict with download result
         """
+        # Normalize falsy file_params (e.g. an empty dict from API JSON
+        # parsing) to None so gate conditions behave consistently (#1058).
+        file_params = file_params or None
+
         logger.debug(
             "[download] download_from_civitai called: model_id=%s, model_version_id=%s, "
             "source=%s, file_params=%s",
@@ -1152,9 +1312,13 @@ class DownloadManager:
         use_save_dir_as_root: bool = False,
     ) -> Dict[str, Any]:
         """Wrapper for original download_from_civitai implementation"""
+        file_params = file_params or None
         try:
-            # Check if model version already exists in library
+            # Check if model version already exists in library.
-            if model_version_id is not None:
+            # With an explicit file selection (file_params) the version-level
+            # check is deferred until after the metadata fetch, when the target
+            # file can be resolved and checked individually (#1058).
+            if model_version_id is not None and file_params is None:
                 # Check both scanners
                 lora_scanner = await self._get_lora_scanner()
                 checkpoint_scanner = await self._get_checkpoint_scanner()
@@ -1235,8 +1399,26 @@ class DownloadManager:
                 except (TypeError, ValueError):
                     resolved_version_id = None
 
+            # Resolve the explicitly selected file (if any) up front so the
+            # existence gates and the actual file selection below always agree
+            # on the target file (#1058).
+            target_file: Optional[Dict[str, Any]] = None
+            if file_params is not None:
+                target_file = self._resolve_target_file(
+                    version_info.get("files") or [], file_params
+                )
+                if target_file is None:
+                    logger.warning(
+                        "[download] file_params provided but no file matched; "
+                        "falling back to version-level checks and primary file "
+                        "selection (model_version_id=%s)",
+                        resolved_version_id,
+                    )
+            explicit_file = target_file is not None
+
             if (
-                get_settings_manager().get_skip_previously_downloaded_model_versions()
+                not explicit_file
+                and get_settings_manager().get_skip_previously_downloaded_model_versions()
                 and resolved_version_id is not None
                 and await self._has_been_downloaded(model_type, resolved_version_id)
             ):
@@ -1346,9 +1528,38 @@ class DownloadManager:
                         f"baseModel '{base_model_value}' is a known diffusion model, routing to unet folder"
                     )
 
-            # Case 2: model_version_id was None, check after getting version_info
+            # Existence check after the metadata fetch (#1058):
-            if model_version_id is None:
+            # - An explicit file selection only blocks when THIS file is
-                version_id = version_info.get("id")
+            #   already in the library; other files of the same version
+            #   remain downloadable.
+            # - Without file_params (or when file_params failed to resolve),
+            #   keep version-level protection. The case "model_version_id
+            #   given + no file_params" was already covered by the early
+            #   gate above.
+            if explicit_file and resolved_version_id is not None:
+                existing_entry = await self._find_local_file_entry(
+                    model_type, resolved_version_id, target_file
+                )
+                if existing_entry is not None:
+                    error_message = (
+                        f"File '{target_file.get('name')}' from model version "
+                        f"{resolved_version_id} already exists in {model_type} library"
+                    )
+                    logger.info("[download] %s", error_message)
+                    return {"success": False, "error": error_message}
+                logger.info(
+                    "[download] File '%s' of model version %s not in %s library — "
+                    "download allowed (other files of this version may exist locally)",
+                    target_file.get("name"), resolved_version_id, model_type,
+                )
+            elif file_params is not None or model_version_id is None:
+                # Case 2: model_version_id was None, or file_params did not
+                # resolve to a concrete file — check at version level.
+                version_id = (
+                    resolved_version_id
+                    if resolved_version_id is not None
+                    else version_info.get("id")
+                )
 
                 if model_type == "lora":
                     # Check lora scanner
@@ -1495,73 +1706,16 @@ class DownloadManager:
             files = version_info.get("files", [])
             file_info = None
 
-            # If file_params is provided, try to find matching file
+            # If file_params is provided, reuse the file resolved right after
-            if file_params and model_version_id:
+            # the metadata fetch so the existence gate and this selection
-                target_file_id = file_params.get("id")
+            # always agree on the target file (#1058).
-                target_type = file_params.get("type", "Model")
+            if file_params is not None:
-                target_format = file_params.get("format")
+                file_info = target_file
-                target_size = file_params.get("size")
-                target_fp = file_params.get("fp")
-                is_primary = file_params.get("isPrimary", False)
-
-                logger.debug(
-                    "[download] file_params received: id=%s, type=%s, format=%s, size=%s, fp=%s, isPrimary=%s, "
-                    "model_version_id=%s, total_files=%d",
-                    target_file_id, target_type, target_format, target_size, target_fp, is_primary,
-                    model_version_id, len(files),
-                )
-
-                if target_file_id:
-                    target_id_str = str(target_file_id)
-                    for f in files:
-                        f_id = f.get("id")
-                        if str(f_id) == target_id_str:
-                            file_info = f
-                            logger.debug(
-                                "[download] MATCH by ID: id=%s name='%s'",
-                                f_id, f.get("name"),
-                            )
-                            break
-                    if not file_info:
-                        logger.debug("[download] No file found with id=%s", target_file_id)
-
-                elif is_primary:
-                    file_info = next(
-                        (
-                            f
-                            for f in files
-                            if f.get("primary")
-                            and f.get("type") in MODEL_WEIGHT_FILE_TYPES
-                        ),
-                        None,
-                    )
-                else:
-                    # Lenient metadata match: only compare fields present on both sides
-                    for f in files:
-                        f_type = f.get("type", "")
-                        if f_type != target_type:
-                            continue
-
-                        f_meta = f.get("metadata", {})
-                        f_format = f_meta.get("format") or f.get("format")
-                        f_size = f_meta.get("size") or f.get("size")
-                        f_fp = f_meta.get("fp") or f.get("fp")
-
-                        if target_format and f_format != target_format:
-                            continue
-                        if target_size and f_size and f_size != target_size:
-                            continue
-                        if target_fp and f_fp and f_fp != target_fp:
-                            continue
-
-                        file_info = f
-                        break
-
                 if not file_info:
                     logger.debug(
                         "[download] No match found via file_params — falling back to primary file lookup",
                     )
-            elif not file_params:
+            else:
                 logger.debug(
                     "[download] No file_params provided (null/None) — will use primary file lookup. "
                     "model_version_id=%s, total_files=%d",

py/services/download_queue_service.py

@@ -64,6 +64,7 @@ class DownloadQueueService:
             model_name TEXT NOT NULL DEFAULT '',
             version_name TEXT DEFAULT '',
             thumbnail_url TEXT DEFAULT '',
+            file_params TEXT,
             status TEXT NOT NULL,
             error TEXT,
             file_path TEXT,
@@ -120,6 +121,18 @@ class DownloadQueueService:
         with self._connect() as conn:
             conn.executescript(self._SCHEMA_TABLES)
 
+            # Databases created by older versions lack
+            # download_history.file_params; add it so retry-from-history can
+            # restore the originally selected file (#1058).
+            history_columns = {
+                row["name"]
+                for row in conn.execute("PRAGMA table_info(download_history)")
+            }
+            if "file_params" not in history_columns:
+                conn.execute(
+                    "ALTER TABLE download_history ADD COLUMN file_params TEXT"
+                )
+
             # Creating the unique index on download_history.download_id can
             # fail if pre-existing rows have duplicate values (e.g. from a
             # previous version that lacked the index).  Deduplicate first so
@@ -418,6 +431,12 @@ class DownloadQueueService:
                 return None
 
             now = completed_at if completed_at is not None else time.time()
+            # Guard against legacy databases whose download_queue table
+            # predates the file_params column.
+            queue_columns = set(row.keys())
+            file_params_json = (
+                row["file_params"] if "file_params" in queue_columns else None
+            )
             conn.execute(
                 "DELETE FROM download_queue WHERE download_id = ?",
                 (download_id,),
@@ -426,9 +445,9 @@ class DownloadQueueService:
                 """
                 INSERT OR IGNORE INTO download_history (
                     download_id, model_id, model_version_id, model_name,
-                    version_name, thumbnail_url, status, error, file_path,
+                    version_name, thumbnail_url, file_params, status, error,
-                    bytes_downloaded, total_bytes, completed_at
+                    file_path, bytes_downloaded, total_bytes, completed_at
-                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
                 """,
                 (
                     row["download_id"],
@@ -437,6 +456,7 @@ class DownloadQueueService:
                     row["model_name"],
                     row["version_name"],
                     row["thumbnail_url"],
+                    file_params_json,
                     status,
                     error,
                     file_path,
@@ -503,6 +523,7 @@ class DownloadQueueService:
         bytes_downloaded: int = 0,
         total_bytes: Optional[int] = None,
         is_already_exists: int = 0,
+        file_params: Optional[dict[str, Any]] = None,
     ) -> int:
         """Insert a record into the download history.
 
@@ -510,6 +531,7 @@ class DownloadQueueService:
         inserted row.
         """
         now = time.time()
+        file_params_json = json.dumps(file_params) if file_params is not None else None
 
         async with self._lock:
             conn = self._get_conn()
@@ -517,9 +539,10 @@ class DownloadQueueService:
                 """
                 INSERT INTO download_history (
                     download_id, model_id, model_version_id, model_name,
-                    version_name, thumbnail_url, status, error, file_path,
+                    version_name, thumbnail_url, file_params, status, error,
-                    bytes_downloaded, total_bytes, completed_at, is_already_exists
+                    file_path, bytes_downloaded, total_bytes, completed_at,
-                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+                    is_already_exists
+                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
                 """,
                 (
                     download_id,
@@ -528,6 +551,7 @@ class DownloadQueueService:
                     model_name,
                     version_name,
                     thumbnail_url,
+                    file_params_json,
                     status,
                     error,
                     file_path,
@@ -702,7 +726,7 @@ class DownloadQueueService:
                     download_id, model_id, model_version_id, model_name,
                     version_name, thumbnail_url, source, file_params,
                     status, priority, added_at
-                ) VALUES (?, ?, ?, ?, ?, ?, ?, NULL, 'queued', 0, ?)
+                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, 'queued', 0, ?)
                 """,
                 (
                     new_id,
@@ -712,6 +736,7 @@ class DownloadQueueService:
                     row["version_name"],
                     row["thumbnail_url"],
                     "retry",
+                    row["file_params"],
                     now,
                 ),
             )
@@ -755,7 +780,7 @@ class DownloadQueueService:
                         download_id, model_id, model_version_id, model_name,
                         version_name, thumbnail_url, source, file_params,
                         status, priority, added_at
-                    ) VALUES (?, ?, ?, ?, ?, ?, ?, NULL, 'queued', 0, ?)
+                    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, 'queued', 0, ?)
                     """,
                     (
                         new_id,
@@ -765,6 +790,7 @@ class DownloadQueueService:
                         row["version_name"],
                         row["thumbnail_url"],
                         "retry",
+                        row["file_params"],
                         now,
                     ),
                 )

static/js/managers/DownloadManager.js

@@ -595,7 +595,10 @@ export class DownloadManager {
                  </div>`;
             }
 
-            const fileBadge = modelFiles.length > 1 && !existsLocally
+            // Always offer the file-selection entry for multi-file versions,
+            // even when the version is already (partially) in the library, so
+            // remaining files can still be downloaded (#1058).
+            const fileBadge = modelFiles.length > 1
                 ? `<span class="file-select-badge" data-version-id="${version.id}">
                      <i class="fas fa-th-list"></i> ${modelFiles.length} ${translate('modals.download.fileSelection.files')} <i class="fas fa-chevron-right badge-arrow"></i>
                    </span>`
@@ -1016,6 +1019,16 @@ export class DownloadManager {
 
             if (!response?.success) {
                 this.loadingManager.setStatus(translate('modals.download.status.finalizing'));
+                const errorMessage = response?.error || 'Unknown error';
+                // A file-level "already in library" rejection is an expected
+                // outcome when browsing files of a partially downloaded
+                // version — surface it as a lightweight toast instead of the
+                // failure summary modal so the user can simply go back and
+                // pick another file (#1058).
+                if (typeof errorMessage === 'string' && errorMessage.includes('already exists in')) {
+                    showToast(errorMessage, {}, 'info');
+                    return false;
+                }
                 showDownloadBatchSummary({
                     total: 1,
                     completed: 0,
@@ -1026,7 +1039,7 @@ export class DownloadManager {
                             source,
                             url: this._buildSingleItemUrl({ modelId, versionId, source }),
                         },
-                        error: response?.error || 'Unknown error',
+                        error: errorMessage,
                         name: displayName,
                     }],
                     onRetry: () => this.executeDownloadWithProgress(retryParams),
@@ -1610,6 +1623,7 @@ export class DownloadManager {
 
             const fileParams = this.selectedFile ? {
                 id: this.selectedFile.id,
+                name: this.selectedFile.name || null,
                 type: this.selectedFile.type || 'Model',
                 format: this.selectedFile.metadata?.format || null,
                 size: this.selectedFile.metadata?.size || null,

tests/frontend/managers/downloadManager.multiFile.test.js

@@ -0,0 +1,164 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+const {
+  DOWNLOAD_MANAGER_MODULE,
+  MODAL_MANAGER_MODULE,
+  UI_HELPERS_MODULE,
+  STATE_MODULE,
+  LOADING_MANAGER_MODULE,
+  API_FACTORY_MODULE,
+  STORAGE_HELPERS_MODULE,
+  FOLDER_TREE_MANAGER_MODULE,
+  I18N_HELPERS_MODULE,
+} = vi.hoisted(() => ({
+  DOWNLOAD_MANAGER_MODULE: new URL('../../../static/js/managers/DownloadManager.js', import.meta.url).pathname,
+  MODAL_MANAGER_MODULE: new URL('../../../static/js/managers/ModalManager.js', import.meta.url).pathname,
+  UI_HELPERS_MODULE: new URL('../../../static/js/utils/uiHelpers.js', import.meta.url).pathname,
+  STATE_MODULE: new URL('../../../static/js/state/index.js', import.meta.url).pathname,
+  LOADING_MANAGER_MODULE: new URL('../../../static/js/managers/LoadingManager.js', import.meta.url).pathname,
+  API_FACTORY_MODULE: new URL('../../../static/js/api/modelApiFactory.js', import.meta.url).pathname,
+  STORAGE_HELPERS_MODULE: new URL('../../../static/js/utils/storageHelpers.js', import.meta.url).pathname,
+  FOLDER_TREE_MANAGER_MODULE: new URL('../../../static/js/components/FolderTreeManager.js', import.meta.url).pathname,
+  I18N_HELPERS_MODULE: new URL('../../../static/js/utils/i18nHelpers.js', import.meta.url).pathname,
+}));
+
+vi.mock(MODAL_MANAGER_MODULE, () => ({
+  modalManager: {
+    showModal: vi.fn(),
+    closeModal: vi.fn(),
+  },
+}));
+
+vi.mock(UI_HELPERS_MODULE, () => ({
+  showToast: vi.fn(),
+}));
+
+vi.mock(STATE_MODULE, () => ({
+  state: {
+    global: {
+      settings: {},
+    },
+  },
+}));
+
+vi.mock(LOADING_MANAGER_MODULE, () => ({
+  LoadingManager: vi.fn(() => ({
+    showSimpleLoading: vi.fn(),
+    hide: vi.fn(),
+    restoreProgressBar: vi.fn(),
+    showDownloadProgress: vi.fn(() => vi.fn()),
+    setStatus: vi.fn(),
+  })),
+}));
+
+vi.mock(API_FACTORY_MODULE, () => ({
+  getModelApiClient: vi.fn(() => ({
+    apiConfig: {
+      config: {
+        displayName: 'LoRA',
+        singularName: 'lora',
+      },
+    },
+  })),
+  resetAndReload: vi.fn(),
+}));
+
+vi.mock(STORAGE_HELPERS_MODULE, () => ({
+  getStorageItem: vi.fn((_key, defaultValue) => defaultValue),
+  setStorageItem: vi.fn(),
+}));
+
+vi.mock(FOLDER_TREE_MANAGER_MODULE, () => ({
+  FolderTreeManager: vi.fn(() => ({
+    clearSelection: vi.fn(),
+    init: vi.fn(),
+  })),
+}));
+
+vi.mock(I18N_HELPERS_MODULE, () => ({
+  translate: vi.fn((_, __, fallback) => fallback ?? ''),
+}));
+
+const MULTI_FILE_VERSION = {
+  id: 201,
+  name: 'Multi-file version',
+  images: [],
+  files: [
+    { id: 1001, type: 'Model', sizeKB: 2048, name: 'file-a.safetensors' },
+    { id: 1002, type: 'Model', sizeKB: 2048, name: 'file-b.safetensors' },
+  ],
+  createdAt: '2026-01-01T00:00:00Z',
+};
+
+const SINGLE_FILE_VERSION = {
+  id: 202,
+  name: 'Single-file version',
+  images: [],
+  files: [{ id: 1003, type: 'Model', sizeKB: 2048, name: 'file-c.safetensors' }],
+  createdAt: '2026-01-01T00:00:00Z',
+};
+
+describe('DownloadManager multi-file version badge (#1058)', () => {
+  let DownloadManager;
+
+  beforeEach(async () => {
+    vi.resetModules();
+    document.body.innerHTML = `
+      <div id="urlStep"></div>
+      <div id="versionStep"></div>
+      <div id="versionList"></div>
+      <button id="nextFromVersion"></button>
+    `;
+    ({ DownloadManager } = await import(DOWNLOAD_MANAGER_MODULE));
+  });
+
+  afterEach(() => {
+    document.body.innerHTML = '';
+  });
+
+  it('shows the file-select badge for a multi-file version already in library', () => {
+    const manager = new DownloadManager();
+    manager.versions = [
+      {
+        ...MULTI_FILE_VERSION,
+        existsLocally: true,
+        localPath: '/models/loras/file-a.safetensors',
+      },
+    ];
+
+    manager.showVersionStep();
+
+    const badge = document.querySelector('.file-select-badge');
+    expect(badge).not.toBeNull();
+    expect(badge.dataset.versionId).toBe('201');
+    expect(badge.textContent).toContain('2');
+    // The in-library badge is still shown alongside
+    expect(document.querySelector('.local-badge')).not.toBeNull();
+  });
+
+  it('still shows the file-select badge for a multi-file version not in library', () => {
+    const manager = new DownloadManager();
+    manager.versions = [{ ...MULTI_FILE_VERSION, existsLocally: false }];
+
+    manager.showVersionStep();
+
+    const badge = document.querySelector('.file-select-badge');
+    expect(badge).not.toBeNull();
+    expect(badge.dataset.versionId).toBe('201');
+  });
+
+  it('does not show the file-select badge for a single-file version in library', () => {
+    const manager = new DownloadManager();
+    manager.versions = [
+      {
+        ...SINGLE_FILE_VERSION,
+        existsLocally: true,
+        localPath: '/models/loras/file-c.safetensors',
+      },
+    ];
+
+    manager.showVersionStep();
+
+    expect(document.querySelector('.file-select-badge')).toBeNull();
+  });
+});

tests/services/test_download_manager_basic.py

@@ -82,14 +82,18 @@ def stub_metadata(monkeypatch):
 
 
 class DummyScanner:
-    def __init__(self, exists: bool = False):
+    def __init__(self, exists: bool = False, raw_data=None):
         self.exists = exists
         self.calls = []
+        self._cache = SimpleNamespace(raw_data=list(raw_data or []))
 
     async def check_model_version_exists(self, version_id):
         self.calls.append(version_id)
         return self.exists
 
+    async def get_cached_data(self):
+        return self._cache
+
 
 @pytest.fixture
 def scanners(monkeypatch):
@@ -1692,3 +1696,310 @@ async def test_download_proceeds_when_history_skip_disabled(monkeypatch, scanner
     assert result.get("skipped") is not True
     history_service.has_been_downloaded.assert_not_called()
     execute_download.assert_awaited_once()
+
+
+# ---------------------------------------------------------------------------
+# Multi-file downloads within a single model version (#1058)
+# ---------------------------------------------------------------------------
+
+
+def _multi_file_payload(include_hashes: bool = True):
+    """Version payload with two weight files under the same version."""
+    files = [
+        {
+            "id": 1001,
+            "type": "Model",
+            "primary": True,
+            "downloadUrl": "https://example.invalid/file-a.safetensors",
+            "name": "file-a.safetensors",
+        },
+        {
+            "id": 1002,
+            "type": "Model",
+            "primary": False,
+            "downloadUrl": "https://example.invalid/file-b.safetensors",
+            "name": "file-b.safetensors",
+        },
+    ]
+    if include_hashes:
+        files[0]["hashes"] = {"SHA256": "AAA111"}
+        files[1]["hashes"] = {"SHA256": "BBB222"}
+    return {
+        "id": 42,
+        "modelId": 7,
+        "model": {"type": "LoRA", "tags": ["fantasy"]},
+        "baseModel": "BaseModel",
+        "creator": {"username": "Author"},
+        "files": files,
+    }
+
+
+def _local_entry(file_name: str, sha256: str, version_id: int = 42):
+    """A library cache entry for one already-downloaded file of a version."""
+    return {
+        "file_name": file_name,
+        "file_path": f"/tmp/{file_name}.safetensors",
+        "sha256": sha256,
+        "civitai": {"id": version_id, "modelId": 7},
+    }
+
+
+def _stub_history_service(monkeypatch, has_been_downloaded: bool = False):
+    history_service = AsyncMock()
+    history_service.has_been_downloaded = AsyncMock(
+        return_value=has_been_downloaded
+    )
+    history_service.mark_downloaded = AsyncMock()
+    monkeypatch.setattr(
+        ServiceRegistry,
+        "get_downloaded_version_history_service",
+        AsyncMock(return_value=history_service),
+    )
+    return history_service
+
+
+@pytest.mark.asyncio
+async def test_download_allows_other_file_of_in_library_version(
+    monkeypatch, scanners, metadata_provider
+):
+    """A different file of an in-library version must still download (#1058)."""
+    scanners.lora._cache.raw_data.append(_local_entry("file-a", "aaa111"))
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload()
+    )
+    _stub_history_service(monkeypatch)
+
+    execute_download = AsyncMock(return_value={"success": True, "download_id": "done"})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={"id": 1002, "type": "Model", "name": "file-b.safetensors"},
+    )
+
+    assert result["success"] is True
+    execute_download.assert_awaited_once()
+    # Version-level gates must not run for an explicit file selection
+    assert scanners.lora.calls == []
+
+
+@pytest.mark.asyncio
+async def test_download_blocks_same_file_of_in_library_version(
+    monkeypatch, scanners, metadata_provider
+):
+    """Re-downloading the SAME file of an in-library version stays blocked."""
+    scanners.lora._cache.raw_data.append(_local_entry("file-a", "aaa111"))
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload()
+    )
+    _stub_history_service(monkeypatch)
+
+    execute_download = AsyncMock(return_value={"success": True})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={"id": 1001, "type": "Model", "name": "file-a.safetensors"},
+    )
+
+    assert result["success"] is False
+    assert "file-a.safetensors" in result["error"]
+    assert "already exists in lora library" in result["error"]
+    execute_download.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_download_unresolvable_file_params_falls_back_to_version_gate(
+    monkeypatch, scanners, metadata_provider
+):
+    """file_params that match no file must not bypass version-level gates."""
+    scanners.lora.exists = True
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload()
+    )
+    _stub_history_service(monkeypatch)
+
+    execute_download = AsyncMock(return_value={"success": True})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={"id": 9999, "type": "Model"},
+    )
+
+    assert result["success"] is False
+    assert result["error"] == "Model version already exists in lora library"
+    execute_download.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_download_empty_file_params_treated_as_no_selection(
+    monkeypatch, scanners, metadata_provider
+):
+    """An empty file_params dict is normalized to None (version-level gates)."""
+    scanners.lora.exists = True
+
+    execute_download = AsyncMock(return_value={"success": True})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={},
+    )
+
+    assert result["success"] is False
+    assert result["error"] == "Model version already exists in lora library"
+    # Early version-level gate fired (file_params normalized to None)
+    assert scanners.lora.calls == [42]
+    execute_download.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_download_explicit_file_bypasses_history_skip(
+    monkeypatch, scanners, metadata_provider
+):
+    """Explicit file selection bypasses the previously-downloaded skip."""
+    get_settings_manager().settings[
+        "skip_previously_downloaded_model_versions"
+    ] = True
+    scanners.lora._cache.raw_data.append(_local_entry("file-a", "aaa111"))
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload()
+    )
+    history_service = _stub_history_service(monkeypatch, has_been_downloaded=True)
+
+    execute_download = AsyncMock(return_value={"success": True, "download_id": "done"})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={"id": 1002, "type": "Model", "name": "file-b.safetensors"},
+    )
+
+    assert result["success"] is True
+    execute_download.assert_awaited_once()
+    # History gate is bypassed before it even queries the service
+    history_service.has_been_downloaded.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_download_file_match_by_name_when_local_hash_missing(
+    monkeypatch, scanners, metadata_provider
+):
+    """Legacy local metadata without sha256 falls back to name matching."""
+    scanners.lora._cache.raw_data.append(_local_entry("file-a", ""))
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload()
+    )
+    _stub_history_service(monkeypatch)
+
+    execute_download = AsyncMock(return_value={"success": True})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={"id": 1001, "type": "Model"},
+    )
+
+    assert result["success"] is False
+    assert "already exists in lora library" in result["error"]
+    execute_download.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_download_no_false_positive_when_both_hashes_empty(
+    monkeypatch, scanners, metadata_provider
+):
+    """Two empty hashes must never compare equal; name decides instead."""
+    # Local entry for a DIFFERENT file of the same version, no hash stored
+    scanners.lora._cache.raw_data.append(_local_entry("file-b", ""))
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload(include_hashes=False)
+    )
+    _stub_history_service(monkeypatch)
+
+    execute_download = AsyncMock(return_value={"success": True, "download_id": "done"})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir="/tmp",
+        file_params={"id": 1001, "type": "Model"},
+    )
+
+    assert result["success"] is True
+    execute_download.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_download_model_id_only_with_file_params_resolves_file(
+    monkeypatch, scanners, metadata_provider
+):
+    """model_id-only requests with file_params resolve the file post-fetch."""
+    scanners.lora.exists = True  # version-level index says "in library"
+    scanners.lora._cache.raw_data.append(_local_entry("file-a", "aaa111"))
+    metadata_provider.get_model_version = AsyncMock(
+        return_value=_multi_file_payload()
+    )
+    _stub_history_service(monkeypatch)
+
+    execute_download = AsyncMock(return_value={"success": True, "download_id": "done"})
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", execute_download, raising=False
+    )
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_id=7,
+        save_dir="/tmp",
+        file_params={"id": 1002, "type": "Model"},
+    )
+
+    assert result["success"] is True
+    execute_download.assert_awaited_once()
+
+
+def test_resolve_target_file_by_id():
+    files = _multi_file_payload()["files"]
+    resolved = DownloadManager._resolve_target_file(files, {"id": 1002})
+    assert resolved is files[1]
+
+
+def test_resolve_target_file_by_primary_flag():
+    files = _multi_file_payload()["files"]
+    resolved = DownloadManager._resolve_target_file(files, {"isPrimary": True})
+    assert resolved is files[0]
+
+
+def test_resolve_target_file_returns_none_for_no_match():
+    files = _multi_file_payload()["files"]
+    assert DownloadManager._resolve_target_file(files, {"id": 9999}) is None
+    assert DownloadManager._resolve_target_file(files, None) is None
+    assert DownloadManager._resolve_target_file(files, {}) is None

tests/services/test_download_queue_service.py

@@ -5,6 +5,8 @@ Covers the new ``download_id``-based code paths in
 compatibility with ``id``.
 """
 
+import json
+import sqlite3
 from pathlib import Path
 
 import pytest
@@ -191,3 +193,131 @@ async def test_retry_unknown_download_id(tmp_path: Path) -> None:
 
     item = await svc.retry_from_history(download_id="dl-nope")
     assert item is None
+
+
+# ---------------------------------------------------------------------------
+# file_params persistence across queue -> history -> retry (#1058)
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_file_params_survive_queue_to_history(tmp_path: Path) -> None:
+    """complete_download copies the queue row's file_params into history."""
+    svc = _make_service(tmp_path)
+    await svc.add_to_queue(
+        download_id="dl-fp",
+        model_id=1,
+        model_version_id=100,
+        file_params={"id": 1002, "type": "Model"},
+    )
+
+    await svc.complete_download("dl-fp", status="failed", error="boom")
+
+    history = await svc.get_history()
+    assert len(history["items"]) == 1
+    assert json.loads(history["items"][0]["file_params"]) == {
+        "id": 1002,
+        "type": "Model",
+    }
+
+
+@pytest.mark.asyncio
+async def test_retry_restores_file_params(tmp_path: Path) -> None:
+    """retry_from_history re-queues with the originally selected file."""
+    svc = _make_service(tmp_path)
+    await svc.add_to_history(
+        download_id="dl-fail-fp",
+        model_id=1,
+        model_version_id=100,
+        status="failed",
+        file_params={"id": 1002, "type": "Model"},
+    )
+
+    item = await svc.retry_from_history(download_id="dl-fail-fp")
+
+    assert item is not None
+    assert item["status"] == "queued"
+    assert json.loads(item["file_params"]) == {"id": 1002, "type": "Model"}
+
+
+@pytest.mark.asyncio
+async def test_retry_all_restores_file_params(tmp_path: Path) -> None:
+    """retry_all_failed preserves file_params for every re-queued item."""
+    svc = _make_service(tmp_path)
+    await svc.add_to_history(
+        download_id="dl-f1", status="failed", file_params={"id": 1001}
+    )
+    await svc.add_to_history(download_id="dl-f2", status="canceled")
+
+    count = await svc.retry_all_failed()
+    assert count == 2
+
+    queue = await svc.get_queue()
+    restored = sorted(
+        (q["file_params"] or "") for q in queue
+    )
+    assert restored[0] == ""  # dl-f2 never had file_params
+    assert json.loads(restored[1]) == {"id": 1001}
+
+
+@pytest.mark.asyncio
+async def test_legacy_history_db_gains_file_params_column(tmp_path: Path) -> None:
+    """Databases created before the file_params column get migrated (#1058)."""
+    db_path = tmp_path / "queue.sqlite"
+    conn = sqlite3.connect(db_path)
+    conn.executescript(
+        """
+        CREATE TABLE download_queue (
+            download_id TEXT PRIMARY KEY,
+            model_id INTEGER,
+            model_version_id INTEGER,
+            model_name TEXT NOT NULL DEFAULT '',
+            version_name TEXT DEFAULT '',
+            thumbnail_url TEXT DEFAULT '',
+            source TEXT,
+            file_params TEXT,
+            status TEXT NOT NULL DEFAULT 'queued',
+            priority INTEGER DEFAULT 0,
+            progress INTEGER DEFAULT 0,
+            bytes_downloaded INTEGER DEFAULT 0,
+            total_bytes INTEGER,
+            bytes_per_second REAL DEFAULT 0.0,
+            error TEXT,
+            file_path TEXT,
+            added_at REAL NOT NULL,
+            started_at REAL,
+            completed_at REAL
+        );
+        CREATE TABLE download_history (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            download_id TEXT,
+            model_id INTEGER,
+            model_version_id INTEGER,
+            model_name TEXT NOT NULL DEFAULT '',
+            version_name TEXT DEFAULT '',
+            thumbnail_url TEXT DEFAULT '',
+            status TEXT NOT NULL,
+            error TEXT,
+            file_path TEXT,
+            bytes_downloaded INTEGER DEFAULT 0,
+            total_bytes INTEGER,
+            completed_at REAL NOT NULL,
+            is_already_exists INTEGER DEFAULT 0
+        );
+        """
+    )
+    conn.close()
+
+    svc = DownloadQueueService(db_path=str(db_path))
+
+    # The migrated table accepts file_params writes
+    await svc.add_to_history(
+        download_id="dl-legacy-fp", status="failed", file_params={"id": 5}
+    )
+    history = await svc.get_history()
+    assert json.loads(history["items"][0]["file_params"]) == {"id": 5}
+
+    # And retry restores them
+    item = await svc.retry_from_history(download_id="dl-legacy-fp")
+    assert item is not None
+    assert json.loads(item["file_params"]) == {"id": 5}