fix(download): save multi-variant files under raw stored filenames (#1100)

The public REST API rewrites files[].name to "{model}_{version}" for
non-LoRA model types, so every precision variant of a multi-file version
shared one name and landed on disk with a random short-hash suffix.

Fetch the raw stored filename from the model-versions/mini endpoint
(always pinned with modelFileId) and use it for the on-disk name and
metadata when available; fall back silently to the REST name otherwise.
CivArchive already serves raw names and is skipped.

tests/services/test_civitai_client.py

@@ -818,3 +818,44 @@ async def test_get_model_by_hash_rejects_empty_placeholder_without_request(downl
     assert result is None
     assert error == "Model not found"
     assert requested == []
+
+
+async def test_get_version_file_mini_returns_payload(downloader):
+    """The mini endpoint returns the raw stored filename (#1100)."""
+    client = await CivitaiClient.get_instance()
+
+    async def fake_make_request(method, url, use_auth=True, **kwargs):
+        assert method == "GET"
+        assert url.endswith("/model-versions/mini/3284136")
+        assert kwargs.get("params") == {"modelFileId": 3168412}
+        assert use_auth is True
+        return True, {"fileName": "CyberRealistic_zit_v8.0_bf16.safetensors"}
+
+    downloader.make_request = fake_make_request
+
+    result = await client.get_version_file_mini(3284136, 3168412)
+
+    assert result == {"fileName": "CyberRealistic_zit_v8.0_bf16.safetensors"}
+
+
+async def test_get_version_file_mini_returns_none_on_failure(downloader):
+    client = await CivitaiClient.get_instance()
+
+    async def fake_make_request(method, url, use_auth=True, **kwargs):
+        return False, "Model file 2 not found in version 1"
+
+    downloader.make_request = fake_make_request
+
+    assert await client.get_version_file_mini(1, 2) is None
+
+
+async def test_get_version_file_mini_propagates_rate_limit(downloader):
+    client = await CivitaiClient.get_instance()
+
+    async def fake_make_request(method, url, use_auth=True, **kwargs):
+        return False, RateLimitError("limited", retry_after=1.0)
+
+    downloader.make_request = fake_make_request
+
+    with pytest.raises(RateLimitError):
+        await client.get_version_file_mini(1, 2)

tests/services/test_download_manager_basic.py

@@ -2098,3 +2098,174 @@ async def test_discard_cleared_downloads_stops_tracking_and_preserves_files(
     # Partial files are preserved for a future resume from disk.
     assert save_path.exists()
     assert control_path.exists()
+
+
+@pytest.mark.asyncio
+async def test_download_uses_raw_file_name_from_mini_endpoint(
+    monkeypatch, scanners, metadata_provider, tmp_path
+):
+    """#1100: when the REST name is rewritten ("{model}_{version}"), the raw
+    stored filename from the mini endpoint wins for the on-disk name."""
+    manager = DownloadManager()
+    get_settings_manager().settings["default_unet_root"] = str(tmp_path / "unet")
+    metadata_provider.payload = {
+        "id": 3284136,
+        "model": {"type": "Checkpoint", "tags": ["realistic"]},
+        "baseModel": "ZImageTurbo",
+        "creator": {"username": "Author"},
+        "files": [
+            {
+                "id": 3168412,
+                "type": "Model",
+                "primary": True,
+                "name": "cyberrealisticZImage_v80.safetensors",
+                "downloadUrl": "https://civitai.com/api/download/models/3284136?fileId=3168412",
+            }
+        ],
+    }
+    metadata_provider.get_version_file_mini = AsyncMock(
+        return_value={"fileName": "CyberRealistic_zit_v8.0_bf16.safetensors"}
+    )
+
+    captured = {}
+
+    async def fake_execute_download(self, **kwargs):
+        captured["download_urls"] = kwargs["download_urls"]
+        captured["file_path"] = kwargs["metadata"].file_path
+        return {"success": True}
+
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", fake_execute_download, raising=False
+    )
+
+    result = await manager.download_from_civitai(
+        model_version_id=3284136,
+        save_dir=str(tmp_path),
+        use_default_paths=True,
+        progress_callback=None,
+        source=None,
+    )
+
+    assert result["success"] is True, result
+    metadata_provider.get_version_file_mini.assert_awaited_once_with(3284136, 3168412)
+    assert captured["file_path"].endswith("CyberRealistic_zit_v8.0_bf16.safetensors")
+    # The file's own pinned downloadUrl is untouched.
+    assert captured["download_urls"] == [
+        "https://civitai.com/api/download/models/3284136?fileId=3168412"
+    ]
+
+
+@pytest.mark.asyncio
+async def test_download_falls_back_to_rest_name_when_mini_fails(
+    monkeypatch, scanners, metadata_provider, tmp_path
+):
+    """A failed/absent mini lookup must keep the previous behavior."""
+    manager = DownloadManager()
+    metadata_provider.payload = {
+        "id": 42,
+        "model": {"type": "Checkpoint", "tags": ["fantasy"]},
+        "baseModel": "BaseModel",
+        "creator": {"username": "Author"},
+        "files": [
+            {
+                "id": 1001,
+                "type": "Model",
+                "primary": True,
+                "name": "rewritten_v10.safetensors",
+                "downloadUrl": "https://example.invalid/file.safetensors",
+            }
+        ],
+    }
+    metadata_provider.get_version_file_mini = AsyncMock(return_value=None)
+
+    captured = {}
+
+    async def fake_execute_download(self, **kwargs):
+        captured["file_path"] = kwargs["metadata"].file_path
+        return {"success": True}
+
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", fake_execute_download, raising=False
+    )
+
+    result = await manager.download_from_civitai(
+        model_version_id=42,
+        save_dir=str(tmp_path),
+        use_default_paths=True,
+        progress_callback=None,
+        source=None,
+    )
+
+    assert result["success"] is True
+    assert captured["file_path"].endswith("rewritten_v10.safetensors")
+
+
+@pytest.mark.asyncio
+async def test_download_skips_mini_lookup_for_civarchive_source(
+    monkeypatch, scanners, metadata_provider, tmp_path
+):
+    """CivArchive already serves raw stored names — no mini call."""
+    manager = DownloadManager()
+    mini_mock = AsyncMock(return_value={"fileName": "should_not_be_used.safetensors"})
+    metadata_provider.get_version_file_mini = mini_mock
+
+    monkeypatch.setattr(
+        download_manager,
+        "get_metadata_provider",
+        AsyncMock(return_value=metadata_provider),
+    )
+
+    captured = {}
+
+    async def fake_execute_download(self, **kwargs):
+        captured["file_path"] = kwargs["metadata"].file_path
+        return {"success": True}
+
+    monkeypatch.setattr(
+        DownloadManager, "_execute_download", fake_execute_download, raising=False
+    )
+
+    result = await manager.download_from_civitai(
+        model_version_id=99,
+        save_dir=str(tmp_path),
+        use_default_paths=True,
+        progress_callback=None,
+        source="civarchive",
+    )
+
+    assert result["success"] is True
+    mini_mock.assert_not_called()
+    assert captured["file_path"].endswith("file.safetensors")
+
+
+@pytest.mark.asyncio
+async def test_fetch_raw_file_name_edge_cases():
+    """_fetch_raw_file_name never raises and strips path components."""
+    manager = DownloadManager()
+
+    provider = SimpleNamespace()
+
+    # Missing version id / file id short-circuit before any provider call.
+    provider.get_version_file_mini = AsyncMock()
+    assert await manager._fetch_raw_file_name(provider, None, 1) is None
+    assert await manager._fetch_raw_file_name(provider, 1, None) is None
+    provider.get_version_file_mini.assert_not_called()
+
+    # Provider without the method (older mocks / non-CivitAI providers).
+    assert await manager._fetch_raw_file_name(object(), 1, 2) is None
+
+    # Non-dict payload, empty fileName.
+    provider.get_version_file_mini = AsyncMock(return_value="oops")
+    assert await manager._fetch_raw_file_name(provider, 1, 2) is None
+    provider.get_version_file_mini = AsyncMock(return_value={"fileName": "  "})
+    assert await manager._fetch_raw_file_name(provider, 1, 2) is None
+
+    # Path components are stripped defensively.
+    provider.get_version_file_mini = AsyncMock(
+        return_value={"fileName": "../evil/model.safetensors"}
+    )
+    assert await manager._fetch_raw_file_name(provider, 1, 2) == "model.safetensors"
+
+    # Provider exceptions degrade to None.
+    provider.get_version_file_mini = AsyncMock(side_effect=RuntimeError("boom"))
+    assert await manager._fetch_raw_file_name(provider, 1, 2) is None

tests/services/test_model_metadata_provider.py

@@ -207,3 +207,62 @@ async def test_retry_helper_retries_normally_for_small_retry_after(monkeypatch):
     result, _ = await helper.run("test", succeeding)
     assert result == {"ok": True}
     assert calls == 2  # Retried once (small retry_after)
+
+
+class MiniCapableProvider(ModelMetadataProvider):
+    """Provider that serves raw file names via the mini endpoint (#1100)."""
+
+    def __init__(self, payload=None) -> None:
+        self.payload = payload
+        self.calls = []
+
+    async def get_model_by_hash(self, model_hash: str):
+        return None, None
+
+    async def get_model_versions(self, model_id: str):
+        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: str):
+        return None, None
+
+    async def get_user_models(self, username: str, cursor=None):
+        return None
+
+    async def get_version_file_mini(self, version_id: int, file_id: int):
+        self.calls.append((version_id, file_id))
+        return self.payload
+
+
+@pytest.mark.asyncio
+async def test_base_provider_get_version_file_mini_defaults_to_none():
+    provider = TrackingProvider()
+    assert await provider.get_version_file_mini(1, 2) is None
+
+
+@pytest.mark.asyncio
+async def test_fallback_get_version_file_mini_returns_first_hit():
+    primary = TrackingProvider()  # base default: None
+    secondary = MiniCapableProvider({"fileName": "raw.safetensors"})
+
+    fallback = FallbackMetadataProvider(
+        [("primary", primary), ("secondary", secondary)],
+    )
+
+    result = await fallback.get_version_file_mini(10, 20)
+
+    assert result == {"fileName": "raw.safetensors"}
+    assert secondary.calls == [(10, 20)]
+
+
+@pytest.mark.asyncio
+async def test_rate_limit_retrying_provider_delegates_get_version_file_mini():
+    inner = MiniCapableProvider({"fileName": "raw.safetensors"})
+    wrapper = RateLimitRetryingProvider(inner, label="inner")
+
+    result = await wrapper.get_version_file_mini(10, 20)
+
+    assert result == {"fileName": "raw.safetensors"}
+    assert inner.calls == [(10, 20)]