feat(metadata): add OpenModelDB metadata provider and model source for upscalers

Add OpenModelDB (openmodeldb.info) as a metadata and download source for
the existing upscaler model type.

Metadata:
- New OpenModelDBClient: fetches the site's bulk JSON dumps, caches them
  on disk (24h TTL + ETag revalidation), and builds a local sha256 index
- New OpenModelDBModelMetadataProvider adapts catalogue entries to the
  CivitAI-shaped version dict contract; registered in the fallback chain
  behind the enable_openmodeldb_api setting (default on), gated to the
  upscaler sub-type so other model types never trigger the dump download
- Persisted provenance uses metadata_source "openmodeldb" plus a nested
  openmodeldb block (page URL, architecture, scale, license)

Images: paired-image LR/SR URLs are ephemeral imgdiff.net sessions, so
displayable images come from the site-hosted auto-generated thumbnails
(model-level cover leads images[], per-image thumbs for the rest); the
original comparison URL is kept in meta.comparisonUrl.

Downloads:
- New OpenModelDBSource (flat model ids, omdb: group prefix) with
  resource filename derivation that recovers names hidden mid-path
  (mediafire) or synthesizes {id}.{type} for folder links
- HTML-gateway mirrors (mediafire/mega/drive) are rejected with a clear
  manual-download hint instead of silently saving an HTML page as .pth
- ModelSource base gains is_valid_source_id / default_subdir_parts /
  resolve_download_url hooks so flat-id sources need no platform branches

UI: "View on OpenModelDB" link in the model modal (downloaded and
hash-enriched models), settings toggle next to the CivArchive one.

tests/services/test_metadata_service.py

@@ -73,6 +73,7 @@ def _stub_settings(**overrides):
     base = {
         "enable_metadata_archive_db": False,
         "enable_civarchive_api": True,
+        "enable_openmodeldb_api": False,
         "metadata_provider_order": "civitai_archive_sqlite",
     }
     base.update(overrides)
@@ -99,6 +100,11 @@ async def _run_initialize(monkeypatch, settings):
         "get_civarchive_client",
         AsyncMock(return_value=object()),
     )
+    monkeypatch.setattr(
+        metadata_service.ServiceRegistry,
+        "get_openmodeldb_client",
+        AsyncMock(return_value=object()),
+    )
 
     # Make MetadataArchiveManager report a usable db path when enabled
     fake_archive = SimpleNamespace(get_database_path=lambda: "/tmp/fake.db")
@@ -172,3 +178,48 @@ async def test_initialize_providers_single_provider_when_only_civitai(monkeypatc
     assert "fallback" not in manager.providers
     assert manager.default_provider == "civitai_api"
 
+
+
+# ---------------------------------------------------------------------------
+# initialize_metadata_providers — OpenModelDB gating + ordering
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_initialize_providers_includes_openmodeldb_when_enabled(monkeypatch):
+    settings = _stub_settings(enable_openmodeldb_api=True)
+    manager = await _run_initialize(monkeypatch, settings)
+    assert "openmodeldb_api" in manager.providers
+    # Local-index lookups run before the rate-limited CivArchive network API.
+    assert _fallback_provider_order(manager) == [
+        "civitai_api",
+        "openmodeldb_api",
+        "civarchive_api",
+    ]
+
+
+@pytest.mark.asyncio
+async def test_initialize_providers_openmodeldb_sqlite_preset(monkeypatch):
+    settings = _stub_settings(
+        enable_metadata_archive_db=True,
+        enable_openmodeldb_api=True,
+        metadata_provider_order="civitai_sqlite_archive",
+    )
+    manager = await _run_initialize(monkeypatch, settings)
+    assert _fallback_provider_order(manager) == [
+        "civitai_api",
+        "openmodeldb_api",
+        "sqlite",
+        "civarchive_api",
+    ]
+
+
+@pytest.mark.asyncio
+async def test_initialize_providers_skips_openmodeldb_when_disabled(monkeypatch):
+    settings = _stub_settings(
+        enable_metadata_archive_db=True,
+        enable_openmodeldb_api=False,
+    )
+    manager = await _run_initialize(monkeypatch, settings)
+    assert "openmodeldb_api" not in manager.providers
+    assert _fallback_provider_order(manager) == ["civitai_api", "civarchive_api", "sqlite"]

tests/services/test_model_sources.py

@@ -195,6 +195,7 @@ class TestCapabilities:
             "modelscope",
             "modelscope-ai",
             "tensorart",
+            "openmodeldb",
         }
 
     def test_labels_are_brand_names(self):
@@ -202,6 +203,7 @@ class TestCapabilities:
         assert source_label("modelscope") == "ModelScope"
         assert source_label("modelscope-ai") == "ModelScope (International)"
         assert source_label("tensorart") == "TensorArt"
+        assert source_label("openmodeldb") == "OpenModelDB"
         assert source_label("unknown", "fallback") == "fallback"
 
 
@@ -920,7 +922,7 @@ class TestSourceIdValidation:
 class TestDownloadSourceRegistry:
     def test_downloadable_sources_excludes_link_only_sites(self):
         platforms = {source.platform for source in downloadable_sources()}
-        assert platforms == {"huggingface", "modelscope", "modelscope-ai"}
+        assert platforms == {"huggingface", "modelscope", "modelscope-ai", "openmodeldb"}
 
     def test_get_download_source_rejects_link_only_platform(self):
         assert get_download_source("tensorart") is None

tests/services/test_openmodeldb_client.py

@@ -0,0 +1,862 @@
+"""Tests for the OpenModelDB client, provider, and sync-service integration."""
+
+from __future__ import annotations
+
+import json
+import time
+from types import SimpleNamespace
+from typing import Any, Dict, Optional
+from unittest.mock import AsyncMock
+
+import pytest
+
+from py.services import openmodeldb_client as openmodeldb_module
+from py.services.metadata_sync_service import MetadataSyncService
+from py.services.model_metadata_provider import (
+    FallbackMetadataProvider,
+    ModelMetadataProvider,
+    OpenModelDBModelMetadataProvider,
+)
+from py.services.openmodeldb_client import (
+    CACHE_TTL_SECONDS,
+    OPENMODELDB_API_BASE,
+    OpenModelDBClient,
+)
+
+
+MODEL_SHA = "a" * 64
+ALT_SHA = "b" * 64
+
+
+def _fixture_dumps() -> Dict[str, Dict[str, Any]]:
+    """Small OpenModelDB catalogue fixture covering the shape variants."""
+    models = {
+        "4x-UltraSharp": {
+            "name": "4x UltraSharp",
+            "author": "kim",
+            "license": "MIT",
+            "tags": ["general"],
+            "description": "Sharp general-purpose upscaler",
+            "date": "2023-01-02",
+            "architecture": "esrgan",
+            "size": ["64nf", "23nb"],
+            "scale": 4,
+            "inputChannels": 3,
+            "outputChannels": 3,
+            "thumbnail": {
+                "type": "paired",
+                "LR": "/thumbs/ultrasharp-lr.png",
+                "SR": "/thumbs/ultrasharp-sr.jpg",
+            },
+            "resources": [
+                {
+                    "platform": "pytorch",
+                    "type": "pth",
+                    "size": 67_000_000,
+                    "sha256": MODEL_SHA,
+                    "urls": ["https://files.example.com/4x-UltraSharp.pth"],
+                },
+                {
+                    "platform": "pytorch",
+                    "type": "safetensors",
+                    "size": 67_100_000,
+                    "sha256": ALT_SHA,
+                    "urls": ["https://files.example.com/4x-UltraSharp.safetensors"],
+                },
+            ],
+            "images": [
+                {
+                    "type": "paired",
+                    "caption": "comparison",
+                    "LR": "https://img.example.com/lr.jpg",
+                    "SR": "https://img.example.com/sr.jpg",
+                    "thumbnail": "/thumbs/small/t.jpg",
+                }
+            ],
+        },
+        "2x-90s-Sonic-LG": {
+            "name": "90s Sonic 2x (Large)",
+            "author": "kim",
+            "architecture": "esrgan",
+            "scale": 2,
+            "thumbnail": {
+                "type": "paired",
+                "LR": "/thumbs/sonic-lr.png",
+                "SR": "/thumbs/sonic-sr.jpg",
+            },
+            "resources": [
+                {
+                    "platform": "pytorch",
+                    "type": "pth",
+                    "size": 9_443_322,
+                    "sha256": "d" * 64,
+                    # mediafire puts the real filename mid-path; the basename
+                    # is just "file".
+                    "urls": [
+                        "https://www.mediafire.com/file/e57pd40qph8nak2/90s_Sonic_2x.pth/file"
+                    ],
+                }
+            ],
+            "images": [
+                {
+                    "type": "paired",
+                    "caption": "Tails",
+                    # Ephemeral imgdiff viewer sessions: 404 outside them.
+                    "LR": "https://imgdiff.net/api/image.php?id=abc&image=2171",
+                    "SR": "https://imgdiff.net/api/image.php?id=abc&image=2172",
+                    "thumbnail": "/thumbs/small/sonic1.jpg",
+                },
+                {
+                    "type": "paired",
+                    "LR": "https://imgdiff.net/api/image.php?id=def&image=2173",
+                    "SR": "https://imgdiff.net/api/image.php?id=def&image=2174",
+                },
+            ],
+        },
+        "mega-only": {
+            "name": "Mega Only",
+            "author": "kim",
+            "architecture": "esrgan",
+            "scale": 4,
+            "resources": [
+                {
+                    "platform": "pytorch",
+                    "type": "pth",
+                    "size": 60_000_000,
+                    "sha256": "e" * 64,
+                    # A folder link carries no filename at all.
+                    "urls": ["https://mega.nz/folder/qZRBmaIY#nIG8KyWFcGNTuMX_XNbJ_g"],
+                }
+            ],
+            "images": [],
+        },
+        "1x-DeJPG": {
+            "name": "1x DeJPG",
+            "author": ["alice", "bob"],
+            "license": None,
+            "tags": ["restoration"],
+            "description": "",
+            "date": "2021-05-06",
+            "architecture": "compact",
+            "size": [],
+            "scale": 1,
+            "inputChannels": 3,
+            "outputChannels": 3,
+            "resources": [
+                {
+                    "platform": "pytorch",
+                    "type": "pth",
+                    "size": 3_000_000,
+                    "sha256": "c" * 64,
+                    "urls": ["https://files.example.com/1x-DeJPG.pth"],
+                }
+            ],
+            "images": [
+                {
+                    "type": "standalone",
+                    "url": "https://img.example.com/dejpg.png",
+                }
+            ],
+        },
+    }
+    users = {
+        "kim": {"name": "Kim"},
+        "alice": {"name": "Alice"},
+        "bob": {"name": "Bob"},
+    }
+    tags = {
+        "general": {"name": "General Purpose"},
+        "restoration": {"name": "Restoration"},
+    }
+    architectures = {
+        "esrgan": {"name": "ESRGAN"},
+        "compact": {"name": "Compact"},
+    }
+    return {
+        "models": models,
+        "users": users,
+        "tags": tags,
+        "architectures": architectures,
+    }
+
+
+class DummyDownloader:
+    """Downloader stub exposing the two entry points the client uses."""
+
+    def __init__(
+        self,
+        *,
+        payloads: Optional[Dict[str, Any]] = None,
+        headers: Optional[Dict[str, Dict[str, str]]] = None,
+        fail: bool = False,
+    ) -> None:
+        self.payloads = payloads or {}
+        self.headers = headers or {}
+        self.fail = fail
+        self.get_calls: list = []
+        self.head_calls: list = []
+
+    async def get_response_headers(self, url, use_auth=False, custom_headers=None):
+        self.head_calls.append(url)
+        if self.fail:
+            return False, "network unreachable"
+        return True, dict(self.headers.get(url, {}))
+
+    async def make_request(self, method, url, use_auth=False, custom_headers=None, **kwargs):
+        self.get_calls.append(url)
+        if self.fail:
+            return False, "network unreachable"
+        return True, self.payloads.get(url)
+
+
+def _dump_url(name: str) -> str:
+    return f"{OPENMODELDB_API_BASE}/{name}.json"
+
+
+@pytest.fixture
+def dumps() -> Dict[str, Dict[str, Any]]:
+    return _fixture_dumps()
+
+
+@pytest.fixture
+def make_client(monkeypatch, tmp_path):
+    """Factory returning a client backed by a DummyDownloader and tmp cache."""
+
+    def _make(downloader: DummyDownloader, **kwargs) -> OpenModelDBClient:
+        monkeypatch.setattr(
+            openmodeldb_module,
+            "get_downloader",
+            AsyncMock(return_value=downloader),
+        )
+        return OpenModelDBClient(cache_dir=str(tmp_path / "omdb"), **kwargs)
+
+    return _make
+
+
+def _payloads_by_url(dumps: Dict[str, Dict[str, Any]]) -> Dict[str, Any]:
+    return {f"{OPENMODELDB_API_BASE}/{name}.json": payload for name, payload in dumps.items()}
+
+
+# ---------------------------------------------------------------------------
+# Index building + CivitAI-shape mapping
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_lookup_maps_catalogue_entry_to_civitai_shape(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash(MODEL_SHA)
+
+    assert error is None
+    assert result is not None
+
+    # Version-level fields
+    assert result["name"] == "4x UltraSharp"
+    assert result["source"] == "openmodeldb"
+    assert result["baseModel"] == "Other"
+    assert result["publishedAt"] == "2023-01-02"
+    assert result["trainedWords"] == []
+    assert result["description"] == "Sharp general-purpose upscaler"
+    # OpenModelDB ids are strings; numeric CivitAI ids must stay absent so
+    # consumers do not treat this as a CivitAI model.
+    assert "id" not in result
+    assert "modelId" not in result
+
+    # Model block
+    model = result["model"]
+    assert model["name"] == "4x UltraSharp"
+    assert model["type"] == "Upscaler"
+    assert model["tags"] == ["General Purpose"]
+    assert model["license"] == "MIT"
+    assert model["description"] == "Sharp general-purpose upscaler"
+
+    # Creator resolved via users.json
+    assert result["creator"]["username"] == "Kim"
+
+    # Files: every resource becomes a file; the hash-matched one is primary.
+    files = result["files"]
+    assert len(files) == 2
+    primary = [f for f in files if f["primary"]]
+    assert len(primary) == 1
+    assert primary[0]["name"] == "4x-UltraSharp.pth"
+    assert primary[0]["hashes"] == {"SHA256": MODEL_SHA.upper()}
+    assert primary[0]["sizeKB"] == pytest.approx(67_000_000 / 1024.0)
+    assert primary[0]["downloadUrl"] == "https://files.example.com/4x-UltraSharp.pth"
+    assert primary[0]["metadata"]["format"] == "PickleTensor"
+    st_file = next(f for f in files if f["name"].endswith(".safetensors"))
+    assert st_file["metadata"]["format"] == "SafeTensor"
+
+    # Images: the model-level thumbnail leads (the card preview derives from
+    # images[0]); paired entries display their site-hosted thumbnail, never
+    # the ephemeral imgdiff originals.
+    images = result["images"]
+    assert len(images) == 2
+    assert images[0]["url"] == "https://openmodeldb.info/thumbs/ultrasharp-sr.jpg"
+    assert images[0]["nsfwLevel"] == 1
+    assert images[1]["url"] == "https://openmodeldb.info/thumbs/small/t.jpg"
+    assert images[1]["meta"] == {"caption": "comparison"}
+    # The thumbnail IS the display URL here, so no separate thumbnailUrl.
+    assert "thumbnailUrl" not in images[1]
+
+    # OpenModelDB-native provenance block
+    omdb = result["openmodeldb"]
+    assert omdb["id"] == "4x-UltraSharp"
+    assert omdb["url"] == "https://openmodeldb.info/models/4x-UltraSharp"
+    assert omdb["authors"] == ["kim"]
+    assert omdb["architecture"] == "esrgan"
+    assert omdb["architectureName"] == "ESRGAN"
+    assert omdb["scale"] == 4
+
+
+@pytest.mark.asyncio
+async def test_lookup_supports_list_authors_and_standalone_images(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash("c" * 64)
+
+    assert error is None
+    assert result["creator"]["username"] == "Alice, Bob"
+    assert result["openmodeldb"]["authors"] == ["alice", "bob"]
+    assert result["images"][0]["url"] == "https://img.example.com/dejpg.png"
+    assert result["model"]["tags"] == ["Restoration"]
+
+
+@pytest.mark.asyncio
+async def test_lookup_never_emits_ephemeral_imgdiff_urls(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash("d" * 64)
+
+    assert error is None
+    images = result["images"]
+    # Model thumbnail first, then the one pair that has a thumbnail; the
+    # thumbnail-less imgdiff pair has no displayable asset and is dropped.
+    assert [img["url"] for img in images] == [
+        "https://openmodeldb.info/thumbs/sonic-sr.jpg",
+        "https://openmodeldb.info/thumbs/small/sonic1.jpg",
+    ]
+    assert all("imgdiff.net" not in img["url"] for img in images)
+    # The original viewer URL survives as reference-only metadata.
+    assert images[1]["meta"]["comparisonUrl"] == (
+        "https://imgdiff.net/api/image.php?id=abc&image=2172"
+    )
+    assert images[1]["meta"]["caption"] == "Tails"
+
+
+@pytest.mark.asyncio
+async def test_lookup_derives_mediafire_mid_path_filename(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash("d" * 64)
+
+    assert error is None
+    # The basename of the mediafire URL is "file"; the real name sits mid-path.
+    assert result["files"][0]["name"] == "90s_Sonic_2x.pth"
+    # No direct-bytes mirror: the HTML-gateway URL stays as the reference.
+    assert result["files"][0]["downloadUrl"].startswith("https://www.mediafire.com/")
+
+
+@pytest.mark.asyncio
+async def test_lookup_synthesizes_filename_for_folder_links(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash("e" * 64)
+
+    assert error is None
+    # A mega.nz folder link has no filename; the catalogue type is authoritative.
+    assert result["files"][0]["name"] == "mega-only.pth"
+
+
+@pytest.mark.asyncio
+async def test_lookup_is_case_insensitive_and_reports_misses(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash(MODEL_SHA.upper())
+    assert error is None and result is not None
+
+    result, error = await client.get_model_by_hash("f" * 64)
+    assert result is None
+    assert error == "Model not found"
+
+
+@pytest.mark.asyncio
+async def test_lookup_unavailable_without_cache_or_network(make_client):
+    downloader = DummyDownloader(fail=True)
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash(MODEL_SHA)
+
+    assert result is None
+    assert error == "OpenModelDB catalogue unavailable"
+
+
+@pytest.mark.asyncio
+async def test_lookup_survives_missing_optional_dumps(make_client, dumps):
+    # users/tags/architectures failing must degrade to raw ids, not break.
+    payloads = _payloads_by_url(dumps)
+    payloads[_dump_url("users")] = None
+    payloads[_dump_url("tags")] = None
+    payloads[_dump_url("architectures")] = None
+    downloader = DummyDownloader(payloads=payloads)
+    client = make_client(downloader)
+
+    result, error = await client.get_model_by_hash(MODEL_SHA)
+
+    assert error is None
+    assert result["creator"]["username"] == "kim"  # raw id fallback
+    assert result["model"]["tags"] == ["general"]  # raw id fallback
+    assert result["openmodeldb"]["architectureName"] == "esrgan"
+
+
+# ---------------------------------------------------------------------------
+# Disk cache, TTL, and conditional revalidation
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_disk_cache_written_and_reused_without_network(make_client, dumps):
+    payloads = _payloads_by_url(dumps)
+    downloader = DummyDownloader(payloads=payloads)
+    client = make_client(downloader)
+
+    result, _ = await client.get_model_by_hash(MODEL_SHA)
+    assert result is not None
+    assert len(downloader.get_calls) == 4  # all four dumps fetched once
+
+    # A second lookup hits the warm in-memory index: no additional HTTP.
+    result, _ = await client.get_model_by_hash(MODEL_SHA)
+    assert result is not None
+    assert len(downloader.get_calls) == 4
+    assert len(downloader.head_calls) == 4  # HEAD probes from the initial fetch only
+
+    # A fresh client instance (simulating a restart) within the TTL reads the
+    # disk cache without any network traffic.
+    offline = DummyDownloader(fail=True)
+    client2 = make_client(offline)
+    result, error = await client2.get_model_by_hash(MODEL_SHA)
+    assert error is None
+    assert result["name"] == "4x UltraSharp"
+    assert offline.get_calls == []
+    assert offline.head_calls == []
+
+
+@pytest.mark.asyncio
+async def test_expired_cache_revalidates_with_etag(make_client, dumps, tmp_path):
+    cache_dir = tmp_path / "omdb"
+    payloads = _payloads_by_url(dumps)
+    etags = {name: f'"etag-{name}"' for name in dumps}
+    headers = {
+        url: {"ETag": etags[name], "Last-Modified": "Wed, 01 Jan 2025 00:00:00 GMT"}
+        for name, url in ((n, _dump_url(n)) for n in dumps)
+    }
+    downloader = DummyDownloader(payloads=payloads, headers=headers)
+    client = make_client(downloader)
+
+    await client.get_model_by_hash(MODEL_SHA)
+    assert len(downloader.get_calls) == 4
+
+    # Force the disk cache to look stale.
+    meta_path = cache_dir / "_meta.json"
+    meta = json.loads(meta_path.read_text())
+    meta["fetched_at"] = time.time() - (CACHE_TTL_SECONDS + 60)
+    meta_path.write_text(json.dumps(meta))
+
+    # Unchanged etags -> cached bodies reused, no GET re-download.
+    downloader2 = DummyDownloader(payloads=None, headers=headers)
+    client2 = make_client(downloader2)
+    result, error = await client2.get_model_by_hash(MODEL_SHA)
+    assert error is None and result is not None
+    assert len(downloader2.head_calls) == 4
+    assert downloader2.get_calls == []
+
+    # The TTL marker is refreshed even though bodies were reused.
+    meta = json.loads(meta_path.read_text())
+    assert meta["fetched_at"] > time.time() - 60
+    assert meta["etags"]["models"] == '"etag-models"'
+
+
+@pytest.mark.asyncio
+async def test_expired_cache_refetches_changed_dump(make_client, dumps, tmp_path):
+    cache_dir = tmp_path / "omdb"
+    payloads = _payloads_by_url(dumps)
+    old_etags = {
+        _dump_url(name): {"ETag": f'"old-{name}"'} for name in dumps
+    }
+    downloader = DummyDownloader(payloads=payloads, headers=old_etags)
+    client = make_client(downloader)
+    await client.get_model_by_hash(MODEL_SHA)
+
+    meta_path = cache_dir / "_meta.json"
+    meta = json.loads(meta_path.read_text())
+    meta["fetched_at"] = time.time() - (CACHE_TTL_SECONDS + 60)
+    meta_path.write_text(json.dumps(meta))
+
+    # Server reports a new etag for models.json only -> only it is re-downloaded.
+    new_headers = dict(old_etags)
+    new_headers[_dump_url("models")] = {"ETag": '"new-models"'}
+    downloader2 = DummyDownloader(payloads=payloads, headers=new_headers)
+    client2 = make_client(downloader2)
+    result, error = await client2.get_model_by_hash(MODEL_SHA)
+    assert error is None and result is not None
+    assert downloader2.get_calls == [_dump_url("models")]
+
+    meta = json.loads(meta_path.read_text())
+    assert meta["etags"]["models"] == '"new-models"'
+    assert meta["etags"]["users"] == '"old-users"'
+
+
+@pytest.mark.asyncio
+async def test_network_failure_falls_back_to_stale_cache(make_client, dumps, tmp_path):
+    cache_dir = tmp_path / "omdb"
+    payloads = _payloads_by_url(dumps)
+    downloader = DummyDownloader(payloads=payloads)
+    client = make_client(downloader)
+    await client.get_model_by_hash(MODEL_SHA)
+
+    meta_path = cache_dir / "_meta.json"
+    meta = json.loads(meta_path.read_text())
+    meta["fetched_at"] = time.time() - (CACHE_TTL_SECONDS + 60)
+    meta_path.write_text(json.dumps(meta))
+
+    offline = DummyDownloader(fail=True)
+    client2 = make_client(offline)
+    result, error = await client2.get_model_by_hash(MODEL_SHA)
+    assert error is None
+    assert result["name"] == "4x UltraSharp"
+
+
+# ---------------------------------------------------------------------------
+# Provider wrapper
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_provider_delegates_and_declares_unsupported_surface(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+    provider = OpenModelDBModelMetadataProvider(client)
+
+    result, error = await provider.get_model_by_hash(MODEL_SHA)
+    assert error is None and result is not None
+
+    assert await provider.get_model_versions("4x-UltraSharp") is None
+    assert await provider.get_model_version(model_id=1) is None
+    version, version_error = await provider.get_model_version_info("123")
+    assert version is None and version_error == "Model not found"
+    assert await provider.get_user_models("kim") is None
+
+
+@pytest.mark.asyncio
+async def test_fallback_chain_continues_past_openmodeldb_miss(make_client, dumps):
+    downloader = DummyDownloader(payloads=_payloads_by_url(dumps))
+    client = make_client(downloader)
+    openmodeldb = OpenModelDBModelMetadataProvider(client)
+
+    class _HitProvider(ModelMetadataProvider):
+        async def get_model_by_hash(self, model_hash):
+            return {"source": "elsewhere", "model": {"name": "Hit"}}, None
+
+        async def get_model_versions(self, model_id):
+            return None
+
+        async def get_model_version(self, model_id=None, version_id=None):
+            return None
+
+        async def get_model_version_info(self, version_id):
+            return None, None
+
+        async def get_user_models(self, username, cursor=None):
+            return None
+
+    fallback = FallbackMetadataProvider(
+        [("openmodeldb_api", openmodeldb), ("other", _HitProvider())]
+    )
+
+    result, error = await fallback.get_model_by_hash("f" * 64)
+    assert result is not None
+    assert result["model"]["name"] == "Hit"
+
+
+# ---------------------------------------------------------------------------
+# FallbackMetadataProvider.excluding + sync-service sub_type gating
+# ---------------------------------------------------------------------------
+
+
+class _RecordingProvider(ModelMetadataProvider):
+    def __init__(self, label: str, result: Optional[Dict[str, Any]] = None) -> None:
+        self.label = label
+        self.result = result
+        self.calls: list = []
+
+    async def get_model_by_hash(self, model_hash: str):
+        self.calls.append(model_hash)
+        return self.result, None if self.result else "Model not found"
+
+    async def get_model_versions(self, model_id):
+        return None
+
+    async def get_model_version(self, model_id=None, version_id=None):
+        return None
+
+    async def get_model_version_info(self, version_id):
+        return None, None
+
+    async def get_user_models(self, username, cursor=None):
+        return None
+
+
+def test_fallback_excluding_drops_named_providers():
+    civitai = _RecordingProvider("civitai_api")
+    openmodeldb = _RecordingProvider("openmodeldb_api")
+    fallback = FallbackMetadataProvider(
+        [("civitai_api", civitai), ("openmodeldb_api", openmodeldb)]
+    )
+
+    filtered = fallback.excluding({"openmodeldb_api"})
+    assert filtered is not fallback
+    assert filtered._provider_labels == ["civitai_api"]
+    # Original chain is untouched.
+    assert fallback._provider_labels == ["civitai_api", "openmodeldb_api"]
+    # Empty/no-op exclusions return the same instance.
+    assert fallback.excluding(set()) is fallback
+
+
+def _build_sync_service(default_provider, provider_selector):
+    metadata_manager = SimpleNamespace(save_metadata=AsyncMock())
+    preview_service = SimpleNamespace(ensure_preview_for_metadata=AsyncMock())
+    settings = SimpleNamespace(get=lambda key, default=None: default)
+    return MetadataSyncService(
+        metadata_manager=metadata_manager,
+        preview_service=preview_service,
+        settings=settings,
+        default_metadata_provider_factory=AsyncMock(return_value=default_provider),
+        metadata_provider_selector=provider_selector,
+    )
+
+
+@pytest.mark.asyncio
+async def test_sync_gates_openmodeldb_out_for_non_upscalers(tmp_path):
+    civitai = _RecordingProvider("civitai_api")
+    openmodeldb = _RecordingProvider(
+        "openmodeldb_api", result={"source": "openmodeldb", "model": {"name": "OMDB"}}
+    )
+    fallback = FallbackMetadataProvider(
+        [("civitai_api", civitai), ("openmodeldb_api", openmodeldb)]
+    )
+    service = _build_sync_service(fallback, AsyncMock())
+
+    model_data: Dict[str, Any] = {
+        "model_name": "lora",
+        "file_path": str(tmp_path / "lora.safetensors"),
+        # No sub_type (a LoRA): openmodeldb must not be consulted.
+    }
+    ok, _ = await service.fetch_and_update_model(
+        sha256="abc",
+        file_path=model_data["file_path"],
+        model_data=model_data,
+        update_cache_func=AsyncMock(return_value=True),
+    )
+    assert ok is False  # nothing found anywhere
+    assert civitai.calls == ["abc"]
+    assert openmodeldb.calls == []
+
+
+@pytest.mark.asyncio
+async def test_sync_consults_openmodeldb_for_upscalers(tmp_path):
+    civitai = _RecordingProvider("civitai_api")
+    openmodeldb = _RecordingProvider(
+        "openmodeldb_api",
+        result={
+            "source": "openmodeldb",
+            "name": "4x UltraSharp",
+            "model": {"name": "4x UltraSharp", "type": "Upscaler", "tags": []},
+            "files": [{"name": "x.pth", "hashes": {"SHA256": "ABC"}}],
+            "images": [],
+        },
+    )
+    fallback = FallbackMetadataProvider(
+        [("civitai_api", civitai), ("openmodeldb_api", openmodeldb)]
+    )
+    service = _build_sync_service(fallback, AsyncMock())
+
+    model_data: Dict[str, Any] = {
+        "model_name": "upscaler",
+        "file_path": str(tmp_path / "upscaler.pth"),
+        "sub_type": "upscaler",
+    }
+    ok, error = await service.fetch_and_update_model(
+        sha256="abc",
+        file_path=model_data["file_path"],
+        model_data=model_data,
+        update_cache_func=AsyncMock(return_value=True),
+    )
+    assert ok is True, error
+    assert civitai.calls == ["abc"]
+    assert openmodeldb.calls == ["abc"]
+    assert model_data["metadata_source"] == "openmodeldb"
+
+
+@pytest.mark.asyncio
+async def test_sync_deleted_upscaler_still_reaches_openmodeldb(tmp_path):
+    openmodeldb = _RecordingProvider(
+        "openmodeldb_api",
+        result={
+            "source": "openmodeldb",
+            "name": "Recovered",
+            "model": {"name": "Recovered", "type": "Upscaler", "tags": []},
+            "files": [],
+            "images": [],
+        },
+    )
+
+    async def selector(name):
+        if name == "openmodeldb_api":
+            return openmodeldb
+        raise ValueError(f"Provider '{name}' is not registered")
+
+    service = _build_sync_service(
+        SimpleNamespace(get_model_by_hash=AsyncMock(return_value=(None, "Model not found"))),
+        AsyncMock(side_effect=selector),
+    )
+
+    model_data: Dict[str, Any] = {
+        "model_name": "deleted upscaler",
+        "file_path": str(tmp_path / "deleted.pth"),
+        "sub_type": "upscaler",
+        "civitai_deleted": True,
+        "metadata_source": "openmodeldb",
+    }
+    ok, error = await service.fetch_and_update_model(
+        sha256="abc",
+        file_path=model_data["file_path"],
+        model_data=model_data,
+        update_cache_func=AsyncMock(return_value=True),
+    )
+    assert ok is True, error
+    assert openmodeldb.calls == ["abc"]
+    assert model_data["metadata_source"] == "openmodeldb"
+
+
+@pytest.mark.asyncio
+async def test_sync_openmodeldb_sourced_model_prefers_openmodeldb_provider(tmp_path):
+    """A model downloaded from OpenModelDB refreshes against its catalogue."""
+    civitai = _RecordingProvider("civitai_api")
+    openmodeldb = _RecordingProvider(
+        "openmodeldb_api",
+        result={
+            "source": "openmodeldb",
+            "name": "4x UltraSharp",
+            "model": {"name": "4x UltraSharp", "type": "Upscaler", "tags": []},
+            "files": [{"name": "x.pth", "hashes": {"SHA256": "ABC"}}],
+            "images": [],
+        },
+    )
+
+    async def selector(name):
+        return {"civitai_api": civitai, "openmodeldb_api": openmodeldb}[name]
+
+    service = _build_sync_service(
+        SimpleNamespace(get_model_by_hash=AsyncMock(return_value=(None, "Model not found"))),
+        AsyncMock(side_effect=selector),
+    )
+
+    model_data: Dict[str, Any] = {
+        "model_name": "upscaler",
+        "file_path": str(tmp_path / "upscaler.pth"),
+        "sub_type": "upscaler",
+        "source_platform": "openmodeldb",
+        "source_url": "https://openmodeldb.info/models/4x-UltraSharp",
+    }
+    ok, error = await service.fetch_and_update_model(
+        sha256="abc",
+        file_path=model_data["file_path"],
+        model_data=model_data,
+        update_cache_func=AsyncMock(return_value=True),
+    )
+    assert ok is True, error
+    # The source's own catalogue answers first; CivitAI is not needed.
+    assert openmodeldb.calls == ["abc"]
+    assert civitai.calls == []
+    assert model_data["metadata_source"] == "openmodeldb"
+    # A "not found" from the source provider must not read as civitai-deleted.
+    assert model_data.get("civitai_deleted") is not True
+
+
+@pytest.mark.asyncio
+async def test_sync_openmodeldb_sourced_model_falls_back_to_civitai(tmp_path):
+    """When the OpenModelDB catalogue has no record, CivitAI is still tried."""
+    civitai = _RecordingProvider(
+        "civitai_api",
+        result={
+            "source": "civitai_api",
+            "name": "Also on CivitAI",
+            "model": {"name": "Also on CivitAI", "type": "Upscaler", "tags": []},
+            "files": [{"name": "x.pth", "hashes": {"SHA256": "ABC"}}],
+            "images": [],
+        },
+    )
+    openmodeldb = _RecordingProvider("openmodeldb_api")
+
+    async def selector(name):
+        return {"civitai_api": civitai, "openmodeldb_api": openmodeldb}[name]
+
+    service = _build_sync_service(
+        SimpleNamespace(get_model_by_hash=AsyncMock(return_value=(None, "Model not found"))),
+        AsyncMock(side_effect=selector),
+    )
+
+    model_data: Dict[str, Any] = {
+        "model_name": "upscaler",
+        "file_path": str(tmp_path / "upscaler.pth"),
+        "sub_type": "upscaler",
+        "source_platform": "openmodeldb",
+        "source_url": "https://openmodeldb.info/models/4x-UltraSharp",
+    }
+    ok, error = await service.fetch_and_update_model(
+        sha256="abc",
+        file_path=model_data["file_path"],
+        model_data=model_data,
+        update_cache_func=AsyncMock(return_value=True),
+    )
+    assert ok is True, error
+    assert openmodeldb.calls == ["abc"]
+    assert civitai.calls == ["abc"]
+    assert model_data["metadata_source"] == "civitai_api"
+
+
+@pytest.mark.asyncio
+async def test_sync_huggingface_sourced_model_stays_civitai_only(tmp_path):
+    """Sources without their own provider keep the CivitAI-only behaviour."""
+    civitai = _RecordingProvider("civitai_api")
+
+    async def selector(name):
+        return {"civitai_api": civitai}[name]
+
+    service = _build_sync_service(
+        SimpleNamespace(get_model_by_hash=AsyncMock(return_value=(None, "Model not found"))),
+        AsyncMock(side_effect=selector),
+    )
+
+    model_data: Dict[str, Any] = {
+        "model_name": "lora",
+        "file_path": str(tmp_path / "lora.safetensors"),
+        "source_platform": "huggingface",
+        "source_url": "https://huggingface.co/user/repo",
+    }
+    ok, _ = await service.fetch_and_update_model(
+        sha256="abc",
+        file_path=model_data["file_path"],
+        model_data=model_data,
+        update_cache_func=AsyncMock(return_value=True),
+    )
+    assert ok is False
+    assert civitai.calls == ["abc"]
+    # A "Model not found" from the named provider does not mark deletion.
+    assert model_data.get("civitai_deleted") is not True

tests/services/test_openmodeldb_source.py

@@ -0,0 +1,332 @@
+"""Tests for the OpenModelDB model source (URL parsing, downloads, card context)."""
+
+from __future__ import annotations
+
+from typing import Any, Dict
+from unittest.mock import AsyncMock
+
+import pytest
+
+from py.services.model_sources import (
+    ModelSourceError,
+    detect_source,
+    get_download_source,
+    source_group_key,
+)
+from py.services.model_sources.openmodeldb import OpenModelDBSource
+from py.services.openmodeldb_client import OpenModelDBClient
+
+MODEL_SHA = "a" * 64
+ALT_SHA = "b" * 64
+
+
+def _dumps() -> Dict[str, Dict[str, Any]]:
+    return {
+        "models": {
+            "4x-UltraSharp": {
+                "name": "4x UltraSharp",
+                "author": "kim",
+                "license": "MIT",
+                "tags": ["general"],
+                "description": "Sharp general-purpose upscaler",
+                "date": "2023-01-02",
+                "architecture": "esrgan",
+                "scale": 4,
+                "resources": [
+                    {
+                        "platform": "pytorch",
+                        "type": "pth",
+                        "size": 67_000_000,
+                        "sha256": MODEL_SHA,
+                        "urls": [
+                            "https://files.example.com/4x-UltraSharp.pth",
+                            "https://mega.nz/file/mirror",
+                        ],
+                    },
+                    {
+                        "platform": "pytorch",
+                        "type": "safetensors",
+                        "size": 67_100_000,
+                        "sha256": ALT_SHA,
+                        "urls": ["https://files.example.com/4x-UltraSharp.safetensors"],
+                    },
+                ],
+                "images": [
+                    {
+                        "type": "paired",
+                        "LR": "https://img.example.com/lr.jpg",
+                        "SR": "https://img.example.com/sr.jpg",
+                    }
+                ],
+            },
+            "onnx-only": {
+                "name": "ONNX Only",
+                "author": "kim",
+                "architecture": "esrgan",
+                "scale": 2,
+                "resources": [
+                    {
+                        "platform": "onnx",
+                        "type": "onnx",
+                        "size": 10_000,
+                        "sha256": "c" * 64,
+                        "urls": ["https://files.example.com/onnx-only.onnx"],
+                    }
+                ],
+            },
+            "2x-90s-Sonic-LG": {
+                "name": "90s Sonic 2x (Large)",
+                "author": "kim",
+                "architecture": "esrgan",
+                "scale": 2,
+                "resources": [
+                    {
+                        "platform": "pytorch",
+                        "type": "pth",
+                        "size": 9_443_322,
+                        "sha256": "d" * 64,
+                        "urls": [
+                            "https://www.mediafire.com/file/e57pd40qph8nak2/90s_Sonic_2x.pth/file"
+                        ],
+                    }
+                ],
+            },
+            "mixed-mirror": {
+                "name": "Mixed Mirror",
+                "author": "kim",
+                "architecture": "esrgan",
+                "scale": 4,
+                "resources": [
+                    {
+                        "platform": "pytorch",
+                        "type": "pth",
+                        "size": 60_000_000,
+                        "sha256": "e" * 64,
+                        # Gateway host first, direct mirror second.
+                        "urls": [
+                            "https://mega.nz/folder/qZRBmaIY#nIG8KyWFcGNTuMX_XNbJ_g",
+                            "https://files.example.com/Mixed-Mirror.pth",
+                        ],
+                    }
+                ],
+            },
+        },
+        "users": {"kim": {"name": "Kim"}},
+        "tags": {"general": {"name": "General Purpose"}},
+        "architectures": {"esrgan": {"name": "ESRGAN"}},
+    }
+
+
+@pytest.fixture
+def client(tmp_path, monkeypatch) -> OpenModelDBClient:
+    """A catalogue-loaded client, installed as the singleton for the source."""
+    seeded = OpenModelDBClient(cache_dir=str(tmp_path / "omdb"))
+    seeded._install_payloads(_dumps())
+    monkeypatch.setattr(
+        OpenModelDBClient, "get_instance", AsyncMock(return_value=seeded)
+    )
+    return seeded
+
+
+# ---------------------------------------------------------------------------
+# Identity and URL parsing
+# ---------------------------------------------------------------------------
+
+
+def test_url_parsing_lenient_and_strict():
+    source = OpenModelDBSource()
+    assert source.parse("https://openmodeldb.info/models/4x-UltraSharp") == "4x-UltraSharp"
+    assert (
+        source.parse("https://openmodeldb.info/models/4x-UltraSharp", strict=True)
+        == "4x-UltraSharp"
+    )
+    assert (
+        source.parse("https://openmodeldb.info/models/4x-UltraSharp/", strict=True)
+        == "4x-UltraSharp"
+    )
+    # Query strings are tolerated only in lenient mode.
+    assert source.parse("https://openmodeldb.info/models/4x-UltraSharp?x=1") == "4x-UltraSharp"
+    assert source.parse("https://openmodeldb.info/models/4x-UltraSharp?x=1", strict=True) is None
+    assert source.parse("https://openmodeldb.info/") is None
+
+
+def test_detect_source_and_group_key():
+    ref = detect_source("https://openmodeldb.info/models/4x-UltraSharp")
+    assert ref is not None
+    assert ref.platform == "openmodeldb"
+    assert ref.source_id == "4x-UltraSharp"
+    assert ref.url == "https://openmodeldb.info/models/4x-UltraSharp"
+
+    # The model id IS the published-model identity, so downloads group by it.
+    assert (
+        source_group_key(
+            {"source_url": ref.url, "source_platform": "openmodeldb"}
+        )
+        == "omdb:4x-UltraSharp"
+    )
+
+
+def test_flat_source_id_validation_and_default_paths():
+    source = get_download_source("openmodeldb")
+    assert source is not None
+    assert source.is_valid_source_id("4x-UltraSharp") is True
+    assert source.is_valid_source_id("owner/name") is False
+    assert source.is_valid_source_id("../escape") is False
+    assert source.is_valid_source_id("") is False
+    # Flat catalogue: no owner/repo namespace under the default directory.
+    assert source.default_subdir_parts("4x-UltraSharp") == ("openmodeldb",)
+
+
+def test_capabilities():
+    source = OpenModelDBSource()
+    assert source.supports_download is True
+    assert source.supports_enrichment is True
+    assert source.example_source_id
+    assert source.canonical_url(source.example_source_id).startswith(
+        "https://openmodeldb.info/models/"
+    )
+
+
+# ---------------------------------------------------------------------------
+# File listing and download URL resolution
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_list_files_returns_pytorch_resources_largest_first(client):
+    files = await OpenModelDBSource().list_files("4x-UltraSharp")
+    assert [f["filename"] for f in files] == [
+        "4x-UltraSharp.safetensors",
+        "4x-UltraSharp.pth",
+    ]
+    assert files[0]["size"] == 67_100_000
+
+
+@pytest.mark.asyncio
+async def test_list_files_skips_non_pytorch_resources(client):
+    # `.onnx` is not a loadable weight format, so an onnx-only model has an
+    # empty download list rather than offering an unusable file.
+    assert await OpenModelDBSource().list_files("onnx-only") == []
+
+
+@pytest.mark.asyncio
+async def test_list_files_raises_manual_download_hint_when_mirror_only(client):
+    # Every mirror is an HTML gateway: an empty list would surface in the UI
+    # as "no model files found", so the source reports the actionable cause.
+    with pytest.raises(ModelSourceError) as excinfo:
+        await OpenModelDBSource().list_files("2x-90s-Sonic-LG")
+    assert excinfo.value.status == 400
+    assert "manual" in str(excinfo.value).lower()
+    assert "openmodeldb.info/models/2x-90s-Sonic-LG" in str(excinfo.value)
+
+
+@pytest.mark.asyncio
+async def test_list_files_prefers_direct_mirror_over_gateway(client):
+    files = await OpenModelDBSource().list_files("mixed-mirror")
+    assert files == [{"filename": "Mixed-Mirror.pth", "size": 60_000_000}]
+
+
+@pytest.mark.asyncio
+async def test_resolve_download_url_rejects_html_gateway_mirror(client):
+    with pytest.raises(ModelSourceError) as excinfo:
+        await OpenModelDBSource().resolve_download_url(
+            "2x-90s-Sonic-LG", "90s_Sonic_2x.pth"
+        )
+    assert excinfo.value.status == 400
+    message = str(excinfo.value)
+    assert "mediafire.com" in message
+    assert "openmodeldb.info/models/2x-90s-Sonic-LG" in message
+
+
+@pytest.mark.asyncio
+async def test_resolve_download_url_uses_direct_mirror(client):
+    url = await OpenModelDBSource().resolve_download_url(
+        "mixed-mirror", "Mixed-Mirror.pth"
+    )
+    assert url == "https://files.example.com/Mixed-Mirror.pth"
+
+
+@pytest.mark.asyncio
+async def test_list_files_unknown_model_raises_404(client):
+    with pytest.raises(ModelSourceError) as excinfo:
+        await OpenModelDBSource().list_files("nope")
+    assert excinfo.value.status == 404
+
+
+@pytest.mark.asyncio
+async def test_resolve_download_url_uses_primary_url_only(client):
+    source = OpenModelDBSource()
+    url = await source.resolve_download_url("4x-UltraSharp", "4x-UltraSharp.pth")
+    # Mirrors (mega.nz & co.) need site-specific handling and are never used.
+    assert url == "https://files.example.com/4x-UltraSharp.pth"
+    assert (
+        await source.resolve_download_url("4x-UltraSharp", "4x-UltraSharp.safetensors")
+        == "https://files.example.com/4x-UltraSharp.safetensors"
+    )
+
+
+@pytest.mark.asyncio
+async def test_resolve_download_url_unknown_file_raises_404(client):
+    with pytest.raises(ModelSourceError) as excinfo:
+        await OpenModelDBSource().resolve_download_url("4x-UltraSharp", "nope.pth")
+    assert excinfo.value.status == 404
+
+
+@pytest.mark.asyncio
+async def test_unavailable_catalogue_raises_502(tmp_path, monkeypatch):
+    broken = OpenModelDBClient(cache_dir=str(tmp_path / "omdb"))
+    monkeypatch.setattr(broken, "_ensure_loaded", AsyncMock(return_value=False))
+    monkeypatch.setattr(
+        OpenModelDBClient, "get_instance", AsyncMock(return_value=broken)
+    )
+
+    with pytest.raises(ModelSourceError) as excinfo:
+        await OpenModelDBSource().list_files("4x-UltraSharp")
+    assert excinfo.value.status == 502
+
+    with pytest.raises(ModelSourceError) as excinfo:
+        await OpenModelDBSource().resolve_download_url("4x-UltraSharp", "x.pth")
+    assert excinfo.value.status == 502
+
+
+# ---------------------------------------------------------------------------
+# Card context (download-time hydration)
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_fetch_model_card_context(client):
+    context = await OpenModelDBSource().fetch_model_card_context(
+        "4x-UltraSharp", "4x-UltraSharp.pth", sha256=MODEL_SHA
+    )
+    assert context.description == "Sharp general-purpose upscaler"
+    assert context.model_name == "4x UltraSharp"
+    assert context.license == "MIT"
+    assert context.model_type == "Upscaler"
+    assert context.official_tags == ["General Purpose"]
+    # Paired previews show the upscaled (SR) result.
+    assert context.example_images == ["https://img.example.com/sr.jpg"]
+    assert context.source_model_id == "4x-UltraSharp"
+    assert context.is_empty() is False
+
+
+@pytest.mark.asyncio
+async def test_fetch_model_card_context_unknown_model_is_empty(client):
+    context = await OpenModelDBSource().fetch_model_card_context("nope")
+    assert context.is_empty() is True
+
+
+@pytest.mark.asyncio
+async def test_fetch_model_card_context_survives_catalogue_failure(
+    tmp_path, monkeypatch
+):
+    broken = OpenModelDBClient(cache_dir=str(tmp_path / "omdb"))
+    monkeypatch.setattr(
+        broken, "_ensure_loaded", AsyncMock(side_effect=RuntimeError("boom"))
+    )
+    monkeypatch.setattr(
+        OpenModelDBClient, "get_instance", AsyncMock(return_value=broken)
+    )
+    # Never raises: a lookup fault reads as "the site had nothing extra".
+    context = await OpenModelDBSource().fetch_model_card_context("4x-UltraSharp")
+    assert context.is_empty() is True