Remove unused imports in scanner.py

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

alembic_db/env.py

@@ -8,7 +8,7 @@ from alembic import context
 config = context.config
 
 
-from app.database.models import Base
+from app.database.models import Base, NAMING_CONVENTION
 target_metadata = Base.metadata
 
 # other values from the config, defined by the needs of env.py,
@@ -51,7 +51,10 @@ def run_migrations_online() -> None:
 
     with connectable.connect() as connection:
         context.configure(
-            connection=connection, target_metadata=target_metadata
+            connection=connection,
+            target_metadata=target_metadata,
+            render_as_batch=True,
+            naming_convention=NAMING_CONVENTION,
         )
 
         with context.begin_transaction():

alembic_db/versions/0003_add_metadata_prompt.py

@@ -0,0 +1,66 @@
+"""
+Add system_metadata and prompt_id columns to asset_references.
+Change preview_id FK from assets.id to asset_references.id.
+
+Revision ID: 0003_add_metadata_prompt
+Revises: 0002_merge_to_asset_references
+Create Date: 2026-03-09
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+from app.database.models import NAMING_CONVENTION
+
+revision = "0003_add_metadata_prompt"
+down_revision = "0002_merge_to_asset_references"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    with op.batch_alter_table("asset_references") as batch_op:
+        batch_op.add_column(
+            sa.Column("system_metadata", sa.JSON(), nullable=True)
+        )
+        batch_op.add_column(
+            sa.Column("prompt_id", sa.String(length=36), nullable=True)
+        )
+
+    # Change preview_id FK from assets.id to asset_references.id (self-ref).
+    # Existing values are asset-content IDs that won't match reference IDs,
+    # so null them out first.
+    op.execute("UPDATE asset_references SET preview_id = NULL WHERE preview_id IS NOT NULL")
+    with op.batch_alter_table(
+        "asset_references", naming_convention=NAMING_CONVENTION
+    ) as batch_op:
+        batch_op.drop_constraint(
+            "fk_asset_references_preview_id_assets", type_="foreignkey"
+        )
+        batch_op.create_foreign_key(
+            "fk_asset_references_preview_id_asset_references",
+            "asset_references",
+            ["preview_id"],
+            ["id"],
+            ondelete="SET NULL",
+        )
+
+
+def downgrade() -> None:
+    with op.batch_alter_table(
+        "asset_references", naming_convention=NAMING_CONVENTION
+    ) as batch_op:
+        batch_op.drop_constraint(
+            "fk_asset_references_preview_id_asset_references", type_="foreignkey"
+        )
+        batch_op.create_foreign_key(
+            "fk_asset_references_preview_id_assets",
+            "assets",
+            ["preview_id"],
+            ["id"],
+            ondelete="SET NULL",
+        )
+
+    with op.batch_alter_table("asset_references") as batch_op:
+        batch_op.drop_column("prompt_id")
+        batch_op.drop_column("system_metadata")

app/assets/api/routes.py

@@ -13,6 +13,7 @@ from pydantic import ValidationError
 import folder_paths
 from app import user_manager
 from app.assets.api import schemas_in, schemas_out
+from app.assets.services import schemas
 from app.assets.api.schemas_in import (
     AssetValidationError,
     UploadError,
@@ -38,6 +39,7 @@ from app.assets.services import (
     update_asset_metadata,
     upload_from_temp_path,
 )
+from app.assets.services.tagging import list_tag_histogram
 
 ROUTES = web.RouteTableDef()
 USER_MANAGER: user_manager.UserManager | None = None
@@ -122,6 +124,60 @@ def _validate_sort_field(requested: str | None) -> str:
     return "created_at"
 
 
+def _build_preview_url_from_view(tags: list[str], user_metadata: dict[str, Any] | None) -> str | None:
+    """Build a /api/view preview URL from asset tags and user_metadata filename."""
+    if not user_metadata:
+        return None
+    filename = user_metadata.get("filename")
+    if not filename:
+        return None
+
+    if "input" in tags:
+        view_type = "input"
+    elif "output" in tags:
+        view_type = "output"
+    else:
+        return None
+
+    subfolder = ""
+    if "/" in filename:
+        subfolder, filename = filename.rsplit("/", 1)
+
+    encoded_filename = urllib.parse.quote(filename, safe="")
+    url = f"/api/view?type={view_type}&filename={encoded_filename}"
+    if subfolder:
+        url += f"&subfolder={urllib.parse.quote(subfolder, safe='')}"
+    return url
+
+
+def _build_asset_response(result: schemas.AssetDetailResult | schemas.UploadResult) -> schemas_out.Asset:
+    """Build an Asset response from a service result."""
+    if result.ref.preview_id:
+        preview_detail = get_asset_detail(result.ref.preview_id)
+        if preview_detail:
+            preview_url = _build_preview_url_from_view(preview_detail.tags, preview_detail.ref.user_metadata)
+        else:
+            preview_url = None
+    else:
+        preview_url = _build_preview_url_from_view(result.tags, result.ref.user_metadata)
+    return schemas_out.Asset(
+        id=result.ref.id,
+        name=result.ref.name,
+        asset_hash=result.asset.hash if result.asset else None,
+        size=int(result.asset.size_bytes) if result.asset else None,
+        mime_type=result.asset.mime_type if result.asset else None,
+        tags=result.tags,
+        preview_url=preview_url,
+        preview_id=result.ref.preview_id,
+        user_metadata=result.ref.user_metadata or {},
+        metadata=result.ref.system_metadata,
+        prompt_id=result.ref.prompt_id,
+        created_at=result.ref.created_at,
+        updated_at=result.ref.updated_at,
+        last_access_time=result.ref.last_access_time,
+    )
+
+
 @ROUTES.head("/api/assets/hash/{hash}")
 @_require_assets_feature_enabled
 async def head_asset_by_hash(request: web.Request) -> web.Response:
@@ -164,20 +220,7 @@ async def list_assets_route(request: web.Request) -> web.Response:
         order=order,
     )
 
-    summaries = [
-        schemas_out.AssetSummary(
-            id=item.ref.id,
-            name=item.ref.name,
-            asset_hash=item.asset.hash if item.asset else None,
-            size=int(item.asset.size_bytes) if item.asset else None,
-            mime_type=item.asset.mime_type if item.asset else None,
-            tags=item.tags,
-            created_at=item.ref.created_at,
-            updated_at=item.ref.updated_at,
-            last_access_time=item.ref.last_access_time,
-        )
-        for item in result.items
-    ]
+    summaries = [_build_asset_response(item) for item in result.items]
 
     payload = schemas_out.AssetsList(
         assets=summaries,
@@ -207,18 +250,7 @@ async def get_asset_route(request: web.Request) -> web.Response:
                 {"id": reference_id},
             )
 
-        payload = schemas_out.AssetDetail(
-            id=result.ref.id,
-            name=result.ref.name,
-            asset_hash=result.asset.hash if result.asset else None,
-            size=int(result.asset.size_bytes) if result.asset else None,
-            mime_type=result.asset.mime_type if result.asset else None,
-            tags=result.tags,
-            user_metadata=result.ref.user_metadata or {},
-            preview_id=result.ref.preview_id,
-            created_at=result.ref.created_at,
-            last_access_time=result.ref.last_access_time,
-        )
+        payload = _build_asset_response(result)
     except ValueError as e:
         return _build_error_response(
             404, "ASSET_NOT_FOUND", str(e), {"id": reference_id}
@@ -230,7 +262,7 @@ async def get_asset_route(request: web.Request) -> web.Response:
             USER_MANAGER.get_request_user_id(request),
         )
         return _build_error_response(500, "INTERNAL", "Unexpected server error.")
-    return web.json_response(payload.model_dump(mode="json"), status=200)
+    return web.json_response(payload.model_dump(mode="json", exclude_none=True), status=200)
 
 
 @ROUTES.get(f"/api/assets/{{id:{UUID_RE}}}/content")
@@ -312,32 +344,31 @@ async def create_asset_from_hash_route(request: web.Request) -> web.Response:
             400, "INVALID_JSON", "Request body must be valid JSON."
         )
 
+    # Derive name from hash if not provided
+    name = body.name
+    if name is None:
+        name = body.hash.split(":", 1)[1] if ":" in body.hash else body.hash
+
     result = create_from_hash(
         hash_str=body.hash,
-        name=body.name,
+        name=name,
         tags=body.tags,
         user_metadata=body.user_metadata,
         owner_id=USER_MANAGER.get_request_user_id(request),
+        mime_type=body.mime_type,
+        preview_id=body.preview_id,
     )
     if result is None:
         return _build_error_response(
             404, "ASSET_NOT_FOUND", f"Asset content {body.hash} does not exist"
         )
 
+    asset = _build_asset_response(result)
     payload_out = schemas_out.AssetCreated(
-        id=result.ref.id,
-        name=result.ref.name,
-        asset_hash=result.asset.hash,
-        size=int(result.asset.size_bytes),
-        mime_type=result.asset.mime_type,
-        tags=result.tags,
-        user_metadata=result.ref.user_metadata or {},
-        preview_id=result.ref.preview_id,
-        created_at=result.ref.created_at,
-        last_access_time=result.ref.last_access_time,
+        **asset.model_dump(),
         created_new=result.created_new,
     )
-    return web.json_response(payload_out.model_dump(mode="json"), status=201)
+    return web.json_response(payload_out.model_dump(mode="json", exclude_none=True), status=201)
 
 
 @ROUTES.post("/api/assets")
@@ -358,6 +389,8 @@ async def upload_asset(request: web.Request) -> web.Response:
                 "name": parsed.provided_name,
                 "user_metadata": parsed.user_metadata_raw,
                 "hash": parsed.provided_hash,
+                "mime_type": parsed.provided_mime_type,
+                "preview_id": parsed.provided_preview_id,
             }
         )
     except ValidationError as ve:
@@ -386,6 +419,8 @@ async def upload_asset(request: web.Request) -> web.Response:
                 tags=spec.tags,
                 user_metadata=spec.user_metadata or {},
                 owner_id=owner_id,
+                mime_type=spec.mime_type,
+                preview_id=spec.preview_id,
             )
             if result is None:
                 delete_temp_file_if_exists(parsed.tmp_path)
@@ -410,6 +445,8 @@ async def upload_asset(request: web.Request) -> web.Response:
                 client_filename=parsed.file_client_name,
                 owner_id=owner_id,
                 expected_hash=spec.hash,
+                mime_type=spec.mime_type,
+                preview_id=spec.preview_id,
             )
     except AssetValidationError as e:
         delete_temp_file_if_exists(parsed.tmp_path)
@@ -428,21 +465,13 @@ async def upload_asset(request: web.Request) -> web.Response:
         logging.exception("upload_asset failed for owner_id=%s", owner_id)
         return _build_error_response(500, "INTERNAL", "Unexpected server error.")
 
-    payload = schemas_out.AssetCreated(
-        id=result.ref.id,
-        name=result.ref.name,
-        asset_hash=result.asset.hash,
-        size=int(result.asset.size_bytes),
-        mime_type=result.asset.mime_type,
-        tags=result.tags,
-        user_metadata=result.ref.user_metadata or {},
-        preview_id=result.ref.preview_id,
-        created_at=result.ref.created_at,
-        last_access_time=result.ref.last_access_time,
+    asset = _build_asset_response(result)
+    payload_out = schemas_out.AssetCreated(
+        **asset.model_dump(),
         created_new=result.created_new,
     )
     status = 201 if result.created_new else 200
-    return web.json_response(payload.model_dump(mode="json"), status=status)
+    return web.json_response(payload_out.model_dump(mode="json", exclude_none=True), status=status)
 
 
 @ROUTES.put(f"/api/assets/{{id:{UUID_RE}}}")
@@ -464,15 +493,10 @@ async def update_asset_route(request: web.Request) -> web.Response:
             name=body.name,
             user_metadata=body.user_metadata,
             owner_id=USER_MANAGER.get_request_user_id(request),
+            mime_type=body.mime_type,
+            preview_id=body.preview_id,
         )
-        payload = schemas_out.AssetUpdated(
-            id=result.ref.id,
-            name=result.ref.name,
-            asset_hash=result.asset.hash if result.asset else None,
-            tags=result.tags,
-            user_metadata=result.ref.user_metadata or {},
-            updated_at=result.ref.updated_at,
-        )
+        payload = _build_asset_response(result)
     except PermissionError as pe:
         return _build_error_response(403, "FORBIDDEN", str(pe), {"id": reference_id})
     except ValueError as ve:
@@ -486,7 +510,7 @@ async def update_asset_route(request: web.Request) -> web.Response:
             USER_MANAGER.get_request_user_id(request),
         )
         return _build_error_response(500, "INTERNAL", "Unexpected server error.")
-    return web.json_response(payload.model_dump(mode="json"), status=200)
+    return web.json_response(payload.model_dump(mode="json", exclude_none=True), status=200)
 
 
 @ROUTES.delete(f"/api/assets/{{id:{UUID_RE}}}")
@@ -555,7 +579,7 @@ async def get_tags(request: web.Request) -> web.Response:
     payload = schemas_out.TagsList(
         tags=tags, total=total, has_more=(query.offset + len(tags)) < total
     )
-    return web.json_response(payload.model_dump(mode="json"))
+    return web.json_response(payload.model_dump(mode="json", exclude_none=True))
 
 
 @ROUTES.post(f"/api/assets/{{id:{UUID_RE}}}/tags")
@@ -603,7 +627,7 @@ async def add_asset_tags(request: web.Request) -> web.Response:
         )
         return _build_error_response(500, "INTERNAL", "Unexpected server error.")
 
-    return web.json_response(payload.model_dump(mode="json"), status=200)
+    return web.json_response(payload.model_dump(mode="json", exclude_none=True), status=200)
 
 
 @ROUTES.delete(f"/api/assets/{{id:{UUID_RE}}}/tags")
@@ -650,7 +674,29 @@ async def delete_asset_tags(request: web.Request) -> web.Response:
         )
         return _build_error_response(500, "INTERNAL", "Unexpected server error.")
 
-    return web.json_response(payload.model_dump(mode="json"), status=200)
+    return web.json_response(payload.model_dump(mode="json", exclude_none=True), status=200)
+
+
+@ROUTES.get("/api/assets/tags/refine")
+@_require_assets_feature_enabled
+async def get_tags_refine(request: web.Request) -> web.Response:
+    """GET request to get tag histogram for filtered assets."""
+    query_dict = get_query_dict(request)
+    try:
+        q = schemas_in.TagsRefineQuery.model_validate(query_dict)
+    except ValidationError as ve:
+        return _build_validation_error_response("INVALID_QUERY", ve)
+
+    tag_counts = list_tag_histogram(
+        owner_id=USER_MANAGER.get_request_user_id(request),
+        include_tags=q.include_tags,
+        exclude_tags=q.exclude_tags,
+        name_contains=q.name_contains,
+        metadata_filter=q.metadata_filter,
+        limit=q.limit,
+    )
+    payload = schemas_out.TagHistogram(tag_counts=tag_counts)
+    return web.json_response(payload.model_dump(mode="json", exclude_none=True), status=200)
 
 
 @ROUTES.post("/api/assets/seed")

app/assets/api/schemas_in.py

@@ -45,6 +45,8 @@ class ParsedUpload:
     user_metadata_raw: str | None
     provided_hash: str | None
     provided_hash_exists: bool | None
+    provided_mime_type: str | None = None
+    provided_preview_id: str | None = None
 
 
 class ListAssetsQuery(BaseModel):
@@ -98,11 +100,18 @@ class ListAssetsQuery(BaseModel):
 class UpdateAssetBody(BaseModel):
     name: str | None = None
     user_metadata: dict[str, Any] | None = None
+    mime_type: str | None = None
+    preview_id: str | None = None
 
     @model_validator(mode="after")
     def _validate_at_least_one_field(self):
-        if self.name is None and self.user_metadata is None:
-            raise ValueError("Provide at least one of: name, user_metadata.")
+        if all(
+            v is None
+            for v in (self.name, self.user_metadata, self.mime_type, self.preview_id)
+        ):
+            raise ValueError(
+                "Provide at least one of: name, user_metadata, mime_type, preview_id."
+            )
         return self
 
 
@@ -110,9 +119,11 @@ class CreateFromHashBody(BaseModel):
     model_config = ConfigDict(extra="ignore", str_strip_whitespace=True)
 
     hash: str
-    name: str
+    name: str | None = None
     tags: list[str] = Field(default_factory=list)
     user_metadata: dict[str, Any] = Field(default_factory=dict)
+    mime_type: str | None = None
+    preview_id: str | None = None
 
     @field_validator("hash")
     @classmethod
@@ -138,6 +149,44 @@ class CreateFromHashBody(BaseModel):
         return []
 
 
+class TagsRefineQuery(BaseModel):
+    include_tags: list[str] = Field(default_factory=list)
+    exclude_tags: list[str] = Field(default_factory=list)
+    name_contains: str | None = None
+    metadata_filter: dict[str, Any] | None = None
+    limit: conint(ge=1, le=1000) = 100
+
+    @field_validator("include_tags", "exclude_tags", mode="before")
+    @classmethod
+    def _split_csv_tags(cls, v):
+        if v is None:
+            return []
+        if isinstance(v, str):
+            return [t.strip() for t in v.split(",") if t.strip()]
+        if isinstance(v, list):
+            out: list[str] = []
+            for item in v:
+                if isinstance(item, str):
+                    out.extend([t.strip() for t in item.split(",") if t.strip()])
+            return out
+        return v
+
+    @field_validator("metadata_filter", mode="before")
+    @classmethod
+    def _parse_metadata_json(cls, v):
+        if v is None or isinstance(v, dict):
+            return v
+        if isinstance(v, str) and v.strip():
+            try:
+                parsed = json.loads(v)
+            except Exception as e:
+                raise ValueError(f"metadata_filter must be JSON: {e}") from e
+            if not isinstance(parsed, dict):
+                raise ValueError("metadata_filter must be a JSON object")
+            return parsed
+        return None
+
+
 class TagsListQuery(BaseModel):
     model_config = ConfigDict(extra="ignore", str_strip_whitespace=True)
 
@@ -186,21 +235,25 @@ class TagsRemove(TagsAdd):
 class UploadAssetSpec(BaseModel):
     """Upload Asset operation.
 
-    - tags: ordered; first is root ('models'|'input'|'output');
+    - tags: optional list; if provided, first is root ('models'|'input'|'output');
             if root == 'models', second must be a valid category
     - name: display name
     - user_metadata: arbitrary JSON object (optional)
     - hash: optional canonical 'blake3:<hex>' for validation / fast-path
+    - mime_type: optional MIME type override
+    - preview_id: optional asset ID for preview
 
     Files are stored using the content hash as filename stem.
     """
 
     model_config = ConfigDict(extra="ignore", str_strip_whitespace=True)
 
-    tags: list[str] = Field(..., min_length=1)
+    tags: list[str] = Field(default_factory=list)
     name: str | None = Field(default=None, max_length=512, description="Display Name")
     user_metadata: dict[str, Any] = Field(default_factory=dict)
     hash: str | None = Field(default=None)
+    mime_type: str | None = Field(default=None)
+    preview_id: str | None = Field(default=None)
 
     @field_validator("hash", mode="before")
     @classmethod
@@ -279,7 +332,7 @@ class UploadAssetSpec(BaseModel):
     @model_validator(mode="after")
     def _validate_order(self):
         if not self.tags:
-            raise ValueError("tags must be provided and non-empty")
+            raise ValueError("at least one tag is required for uploads")
         root = self.tags[0]
         if root not in {"models", "input", "output"}:
             raise ValueError("first tag must be one of: models, input, output")

app/assets/api/schemas_out.py

@@ -4,7 +4,7 @@ from typing import Any
 from pydantic import BaseModel, ConfigDict, Field, field_serializer
 
 
-class AssetSummary(BaseModel):
+class Asset(BaseModel):
     id: str
     name: str
     asset_hash: str | None = None
@@ -12,8 +12,13 @@ class AssetSummary(BaseModel):
     mime_type: str | None = None
     tags: list[str] = Field(default_factory=list)
     preview_url: str | None = None
-    created_at: datetime | None = None
-    updated_at: datetime | None = None
+    preview_id: str | None = None
+    user_metadata: dict[str, Any] = Field(default_factory=dict)
+    is_immutable: bool = False
+    metadata: dict[str, Any] | None = None
+    prompt_id: str | None = None
+    created_at: datetime
+    updated_at: datetime
     last_access_time: datetime | None = None
 
     model_config = ConfigDict(from_attributes=True)
@@ -23,50 +28,16 @@ class AssetSummary(BaseModel):
         return v.isoformat() if v else None
 
 
+class AssetCreated(Asset):
+    created_new: bool
+
+
 class AssetsList(BaseModel):
-    assets: list[AssetSummary]
+    assets: list[Asset]
     total: int
     has_more: bool
 
 
-class AssetUpdated(BaseModel):
-    id: str
-    name: str
-    asset_hash: str | None = None
-    tags: list[str] = Field(default_factory=list)
-    user_metadata: dict[str, Any] = Field(default_factory=dict)
-    updated_at: datetime | None = None
-
-    model_config = ConfigDict(from_attributes=True)
-
-    @field_serializer("updated_at")
-    def _serialize_updated_at(self, v: datetime | None, _info):
-        return v.isoformat() if v else None
-
-
-class AssetDetail(BaseModel):
-    id: str
-    name: str
-    asset_hash: str | None = None
-    size: int | None = None
-    mime_type: str | None = None
-    tags: list[str] = Field(default_factory=list)
-    user_metadata: dict[str, Any] = Field(default_factory=dict)
-    preview_id: str | None = None
-    created_at: datetime | None = None
-    last_access_time: datetime | None = None
-
-    model_config = ConfigDict(from_attributes=True)
-
-    @field_serializer("created_at", "last_access_time")
-    def _serialize_datetime(self, v: datetime | None, _info):
-        return v.isoformat() if v else None
-
-
-class AssetCreated(AssetDetail):
-    created_new: bool
-
-
 class TagUsage(BaseModel):
     name: str
     count: int
@@ -91,3 +62,7 @@ class TagsRemove(BaseModel):
     removed: list[str] = Field(default_factory=list)
     not_present: list[str] = Field(default_factory=list)
     total_tags: list[str] = Field(default_factory=list)
+
+
+class TagHistogram(BaseModel):
+    tag_counts: dict[str, int]

app/assets/api/upload.py

@@ -52,6 +52,8 @@ async def parse_multipart_upload(
     user_metadata_raw: str | None = None
     provided_hash: str | None = None
     provided_hash_exists: bool | None = None
+    provided_mime_type: str | None = None
+    provided_preview_id: str | None = None
 
     file_written = 0
     tmp_path: str | None = None
@@ -128,6 +130,16 @@ async def parse_multipart_upload(
             provided_name = (await field.text()) or None
         elif fname == "user_metadata":
             user_metadata_raw = (await field.text()) or None
+        elif fname == "id":
+            raise UploadError(
+                400,
+                "UNSUPPORTED_FIELD",
+                "Client-provided 'id' is not supported. Asset IDs are assigned by the server.",
+            )
+        elif fname == "mime_type":
+            provided_mime_type = ((await field.text()) or "").strip() or None
+        elif fname == "preview_id":
+            provided_preview_id = ((await field.text()) or "").strip() or None
 
     if not file_present and not (provided_hash and provided_hash_exists):
         raise UploadError(
@@ -152,6 +164,8 @@ async def parse_multipart_upload(
         user_metadata_raw=user_metadata_raw,
         provided_hash=provided_hash,
         provided_hash_exists=provided_hash_exists,
+        provided_mime_type=provided_mime_type,
+        provided_preview_id=provided_preview_id,
     )
 
 

app/assets/database/models.py

@@ -45,13 +45,7 @@ class Asset(Base):
         passive_deletes=True,
     )
 
-    preview_of: Mapped[list[AssetReference]] = relationship(
-        "AssetReference",
-        back_populates="preview_asset",
-        primaryjoin=lambda: Asset.id == foreign(AssetReference.preview_id),
-        foreign_keys=lambda: [AssetReference.preview_id],
-        viewonly=True,
-    )
+    # preview_id on AssetReference is a self-referential FK to asset_references.id
 
     __table_args__ = (
         Index("uq_assets_hash", "hash", unique=True),
@@ -91,11 +85,15 @@ class AssetReference(Base):
     owner_id: Mapped[str] = mapped_column(String(128), nullable=False, default="")
     name: Mapped[str] = mapped_column(String(512), nullable=False)
     preview_id: Mapped[str | None] = mapped_column(
-        String(36), ForeignKey("assets.id", ondelete="SET NULL")
+        String(36), ForeignKey("asset_references.id", ondelete="SET NULL")
     )
     user_metadata: Mapped[dict[str, Any] | None] = mapped_column(
         JSON(none_as_null=True)
     )
+    system_metadata: Mapped[dict[str, Any] | None] = mapped_column(
+        JSON(none_as_null=True), nullable=True, default=None
+    )
+    prompt_id: Mapped[str | None] = mapped_column(String(36), nullable=True, default=None)
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=False), nullable=False, default=get_utc_now
     )
@@ -115,10 +113,10 @@ class AssetReference(Base):
         foreign_keys=[asset_id],
         lazy="selectin",
     )
-    preview_asset: Mapped[Asset | None] = relationship(
-        "Asset",
-        back_populates="preview_of",
+    preview_ref: Mapped[AssetReference | None] = relationship(
+        "AssetReference",
         foreign_keys=[preview_id],
+        remote_side=lambda: [AssetReference.id],
     )
 
     metadata_entries: Mapped[list[AssetReferenceMeta]] = relationship(

app/assets/database/queries/__init__.py

@@ -31,16 +31,21 @@ from app.assets.database.queries.asset_reference import (
     get_unenriched_references,
     get_unreferenced_unhashed_asset_ids,
     insert_reference,
+    list_all_file_paths_by_asset_id,
     list_references_by_asset_id,
     list_references_page,
     mark_references_missing_outside_prefixes,
+    rebuild_metadata_projection,
+    reference_exists,
     reference_exists_for_asset_id,
     restore_references_by_paths,
     set_reference_metadata,
     set_reference_preview,
+    set_reference_system_metadata,
     soft_delete_reference_by_id,
     update_reference_access_time,
     update_reference_name,
+    update_is_missing_by_asset_id,
     update_reference_timestamps,
     update_reference_updated_at,
     upsert_reference,
@@ -54,6 +59,7 @@ from app.assets.database.queries.tags import (
     bulk_insert_tags_and_meta,
     ensure_tags_exist,
     get_reference_tags,
+    list_tag_counts_for_filtered_assets,
     list_tags_with_usage,
     remove_missing_tag_for_asset_id,
     remove_tags_from_reference,
@@ -97,20 +103,26 @@ __all__ = [
     "get_unenriched_references",
     "get_unreferenced_unhashed_asset_ids",
     "insert_reference",
+    "list_all_file_paths_by_asset_id",
     "list_references_by_asset_id",
     "list_references_page",
+    "list_tag_counts_for_filtered_assets",
     "list_tags_with_usage",
     "mark_references_missing_outside_prefixes",
     "reassign_asset_references",
+    "rebuild_metadata_projection",
+    "reference_exists",
     "reference_exists_for_asset_id",
     "remove_missing_tag_for_asset_id",
     "remove_tags_from_reference",
     "restore_references_by_paths",
     "set_reference_metadata",
     "set_reference_preview",
+    "set_reference_system_metadata",
     "soft_delete_reference_by_id",
     "set_reference_tags",
     "update_asset_hash_and_mime",
+    "update_is_missing_by_asset_id",
     "update_reference_access_time",
     "update_reference_name",
     "update_reference_timestamps",

app/assets/database/queries/asset.py

@@ -69,7 +69,7 @@ def upsert_asset(
         if asset.size_bytes != int(size_bytes) and int(size_bytes) > 0:
             asset.size_bytes = int(size_bytes)
             changed = True
-        if mime_type and asset.mime_type != mime_type:
+        if mime_type and not asset.mime_type:
             asset.mime_type = mime_type
             changed = True
         if changed:
@@ -118,7 +118,7 @@ def update_asset_hash_and_mime(
         return False
     if asset_hash is not None:
         asset.hash = asset_hash
-    if mime_type is not None:
+    if mime_type is not None and not asset.mime_type:
         asset.mime_type = mime_type
     return True
 

app/assets/database/queries/asset_reference.py

@@ -10,7 +10,7 @@ from decimal import Decimal
 from typing import NamedTuple, Sequence
 
 import sqlalchemy as sa
-from sqlalchemy import delete, exists, select
+from sqlalchemy import delete, select
 from sqlalchemy.dialects import sqlite
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session, noload
@@ -24,12 +24,14 @@ from app.assets.database.models import (
 )
 from app.assets.database.queries.common import (
     MAX_BIND_PARAMS,
+    apply_metadata_filter,
+    apply_tag_filters,
     build_prefix_like_conditions,
     build_visible_owner_clause,
     calculate_rows_per_statement,
     iter_chunks,
 )
-from app.assets.helpers import escape_sql_like_string, get_utc_now, normalize_tags
+from app.assets.helpers import escape_sql_like_string, get_utc_now
 
 
 def _check_is_scalar(v):
@@ -79,83 +81,6 @@ def convert_metadata_to_rows(key: str, value) -> list[dict]:
     return [{"key": key, "ordinal": 0, "val_json": value}]
 
 
-def _apply_tag_filters(
-    stmt: sa.sql.Select,
-    include_tags: Sequence[str] | None = None,
-    exclude_tags: Sequence[str] | None = None,
-) -> sa.sql.Select:
-    """include_tags: every tag must be present; exclude_tags: none may be present."""
-    include_tags = normalize_tags(include_tags)
-    exclude_tags = normalize_tags(exclude_tags)
-
-    if include_tags:
-        for tag_name in include_tags:
-            stmt = stmt.where(
-                exists().where(
-                    (AssetReferenceTag.asset_reference_id == AssetReference.id)
-                    & (AssetReferenceTag.tag_name == tag_name)
-                )
-            )
-
-    if exclude_tags:
-        stmt = stmt.where(
-            ~exists().where(
-                (AssetReferenceTag.asset_reference_id == AssetReference.id)
-                & (AssetReferenceTag.tag_name.in_(exclude_tags))
-            )
-        )
-    return stmt
-
-
-def _apply_metadata_filter(
-    stmt: sa.sql.Select,
-    metadata_filter: dict | None = None,
-) -> sa.sql.Select:
-    """Apply filters using asset_reference_meta projection table."""
-    if not metadata_filter:
-        return stmt
-
-    def _exists_for_pred(key: str, *preds) -> sa.sql.ClauseElement:
-        return sa.exists().where(
-            AssetReferenceMeta.asset_reference_id == AssetReference.id,
-            AssetReferenceMeta.key == key,
-            *preds,
-        )
-
-    def _exists_clause_for_value(key: str, value) -> sa.sql.ClauseElement:
-        if value is None:
-            no_row_for_key = sa.not_(
-                sa.exists().where(
-                    AssetReferenceMeta.asset_reference_id == AssetReference.id,
-                    AssetReferenceMeta.key == key,
-                )
-            )
-            null_row = _exists_for_pred(
-                key,
-                AssetReferenceMeta.val_json.is_(None),
-                AssetReferenceMeta.val_str.is_(None),
-                AssetReferenceMeta.val_num.is_(None),
-                AssetReferenceMeta.val_bool.is_(None),
-            )
-            return sa.or_(no_row_for_key, null_row)
-
-        if isinstance(value, bool):
-            return _exists_for_pred(key, AssetReferenceMeta.val_bool == bool(value))
-        if isinstance(value, (int, float, Decimal)):
-            num = value if isinstance(value, Decimal) else Decimal(str(value))
-            return _exists_for_pred(key, AssetReferenceMeta.val_num == num)
-        if isinstance(value, str):
-            return _exists_for_pred(key, AssetReferenceMeta.val_str == value)
-        return _exists_for_pred(key, AssetReferenceMeta.val_json == value)
-
-    for k, v in metadata_filter.items():
-        if isinstance(v, list):
-            ors = [_exists_clause_for_value(k, elem) for elem in v]
-            if ors:
-                stmt = stmt.where(sa.or_(*ors))
-        else:
-            stmt = stmt.where(_exists_clause_for_value(k, v))
-    return stmt
 
 
 def get_reference_by_id(
@@ -212,6 +137,21 @@ def reference_exists_for_asset_id(
     return session.execute(q).first() is not None
 
 
+def reference_exists(
+    session: Session,
+    reference_id: str,
+) -> bool:
+    """Return True if a reference with the given ID exists (not soft-deleted)."""
+    q = (
+        select(sa.literal(True))
+        .select_from(AssetReference)
+        .where(AssetReference.id == reference_id)
+        .where(AssetReference.deleted_at.is_(None))
+        .limit(1)
+    )
+    return session.execute(q).first() is not None
+
+
 def insert_reference(
     session: Session,
     asset_id: str,
@@ -336,8 +276,8 @@ def list_references_page(
         escaped, esc = escape_sql_like_string(name_contains)
         base = base.where(AssetReference.name.ilike(f"%{escaped}%", escape=esc))
 
-    base = _apply_tag_filters(base, include_tags, exclude_tags)
-    base = _apply_metadata_filter(base, metadata_filter)
+    base = apply_tag_filters(base, include_tags, exclude_tags)
+    base = apply_metadata_filter(base, metadata_filter)
 
     sort = (sort or "created_at").lower()
     order = (order or "desc").lower()
@@ -366,8 +306,8 @@ def list_references_page(
         count_stmt = count_stmt.where(
             AssetReference.name.ilike(f"%{escaped}%", escape=esc)
         )
-    count_stmt = _apply_tag_filters(count_stmt, include_tags, exclude_tags)
-    count_stmt = _apply_metadata_filter(count_stmt, metadata_filter)
+    count_stmt = apply_tag_filters(count_stmt, include_tags, exclude_tags)
+    count_stmt = apply_metadata_filter(count_stmt, metadata_filter)
 
     total = int(session.execute(count_stmt).scalar_one() or 0)
     refs = session.execute(base).unique().scalars().all()
@@ -379,7 +319,7 @@ def list_references_page(
             select(AssetReferenceTag.asset_reference_id, Tag.name)
             .join(Tag, Tag.name == AssetReferenceTag.tag_name)
             .where(AssetReferenceTag.asset_reference_id.in_(id_list))
-            .order_by(AssetReferenceTag.added_at)
+            .order_by(AssetReferenceTag.tag_name.asc())
         )
         for ref_id, tag_name in rows.all():
             tag_map[ref_id].append(tag_name)
@@ -492,6 +432,42 @@ def update_reference_updated_at(
     )
 
 
+def rebuild_metadata_projection(session: Session, ref: AssetReference) -> None:
+    """Delete and rebuild AssetReferenceMeta rows from merged system+user metadata.
+
+    The merged dict is ``{**system_metadata, **user_metadata}`` so user keys
+    override system keys of the same name.
+    """
+    session.execute(
+        delete(AssetReferenceMeta).where(
+            AssetReferenceMeta.asset_reference_id == ref.id
+        )
+    )
+    session.flush()
+
+    merged = {**(ref.system_metadata or {}), **(ref.user_metadata or {})}
+    if not merged:
+        return
+
+    rows: list[AssetReferenceMeta] = []
+    for k, v in merged.items():
+        for r in convert_metadata_to_rows(k, v):
+            rows.append(
+                AssetReferenceMeta(
+                    asset_reference_id=ref.id,
+                    key=r["key"],
+                    ordinal=int(r["ordinal"]),
+                    val_str=r.get("val_str"),
+                    val_num=r.get("val_num"),
+                    val_bool=r.get("val_bool"),
+                    val_json=r.get("val_json"),
+                )
+            )
+    if rows:
+        session.add_all(rows)
+        session.flush()
+
+
 def set_reference_metadata(
     session: Session,
     reference_id: str,
@@ -505,33 +481,24 @@ def set_reference_metadata(
     ref.updated_at = get_utc_now()
     session.flush()
 
-    session.execute(
-        delete(AssetReferenceMeta).where(
-            AssetReferenceMeta.asset_reference_id == reference_id
-        )
-    )
+    rebuild_metadata_projection(session, ref)
+
+
+def set_reference_system_metadata(
+    session: Session,
+    reference_id: str,
+    system_metadata: dict | None = None,
+) -> None:
+    """Set system_metadata on a reference and rebuild the merged projection."""
+    ref = session.get(AssetReference, reference_id)
+    if not ref:
+        raise ValueError(f"AssetReference {reference_id} not found")
+
+    ref.system_metadata = system_metadata or {}
+    ref.updated_at = get_utc_now()
     session.flush()
 
-    if not user_metadata:
-        return
-
-    rows: list[AssetReferenceMeta] = []
-    for k, v in user_metadata.items():
-        for r in convert_metadata_to_rows(k, v):
-            rows.append(
-                AssetReferenceMeta(
-                    asset_reference_id=reference_id,
-                    key=r["key"],
-                    ordinal=int(r["ordinal"]),
-                    val_str=r.get("val_str"),
-                    val_num=r.get("val_num"),
-                    val_bool=r.get("val_bool"),
-                    val_json=r.get("val_json"),
-                )
-            )
-    if rows:
-        session.add_all(rows)
-        session.flush()
+    rebuild_metadata_projection(session, ref)
 
 
 def delete_reference_by_id(
@@ -571,19 +538,19 @@ def soft_delete_reference_by_id(
 def set_reference_preview(
     session: Session,
     reference_id: str,
-    preview_asset_id: str | None = None,
+    preview_reference_id: str | None = None,
 ) -> None:
     """Set or clear preview_id and bump updated_at. Raises on unknown IDs."""
     ref = session.get(AssetReference, reference_id)
     if not ref:
         raise ValueError(f"AssetReference {reference_id} not found")
 
-    if preview_asset_id is None:
+    if preview_reference_id is None:
         ref.preview_id = None
     else:
-        if not session.get(Asset, preview_asset_id):
-            raise ValueError(f"Preview Asset {preview_asset_id} not found")
-        ref.preview_id = preview_asset_id
+        if not session.get(AssetReference, preview_reference_id):
+            raise ValueError(f"Preview AssetReference {preview_reference_id} not found")
+        ref.preview_id = preview_reference_id
 
     ref.updated_at = get_utc_now()
     session.flush()
@@ -609,6 +576,8 @@ def list_references_by_asset_id(
         session.execute(
             select(AssetReference)
             .where(AssetReference.asset_id == asset_id)
+            .where(AssetReference.is_missing == False)  # noqa: E712
+            .where(AssetReference.deleted_at.is_(None))
             .order_by(AssetReference.id.asc())
         )
         .scalars()
@@ -616,6 +585,25 @@ def list_references_by_asset_id(
     )
 
 
+def list_all_file_paths_by_asset_id(
+    session: Session,
+    asset_id: str,
+) -> list[str]:
+    """Return every file_path for an asset, including soft-deleted/missing refs.
+
+    Used for orphan cleanup where all on-disk files must be removed.
+    """
+    return list(
+        session.execute(
+            select(AssetReference.file_path)
+            .where(AssetReference.asset_id == asset_id)
+            .where(AssetReference.file_path.isnot(None))
+        )
+        .scalars()
+        .all()
+    )
+
+
 def upsert_reference(
     session: Session,
     asset_id: str,
@@ -855,6 +843,22 @@ def bulk_update_is_missing(
     return total
 
 
+def update_is_missing_by_asset_id(
+    session: Session, asset_id: str, value: bool
+) -> int:
+    """Set is_missing flag for ALL references belonging to an asset.
+
+    Returns: Number of rows updated
+    """
+    result = session.execute(
+        sa.update(AssetReference)
+        .where(AssetReference.asset_id == asset_id)
+        .where(AssetReference.deleted_at.is_(None))
+        .values(is_missing=value)
+    )
+    return result.rowcount
+
+
 def delete_references_by_ids(session: Session, reference_ids: list[str]) -> int:
     """Delete references by their IDs.
 

app/assets/database/queries/common.py

@@ -1,12 +1,14 @@
 """Shared utilities for database query modules."""
 
 import os
-from typing import Iterable
+from decimal import Decimal
+from typing import Iterable, Sequence
 
 import sqlalchemy as sa
+from sqlalchemy import exists
 
-from app.assets.database.models import AssetReference
-from app.assets.helpers import escape_sql_like_string
+from app.assets.database.models import AssetReference, AssetReferenceMeta, AssetReferenceTag
+from app.assets.helpers import escape_sql_like_string, normalize_tags
 
 MAX_BIND_PARAMS = 800
 
@@ -52,3 +54,82 @@ def build_prefix_like_conditions(
         escaped, esc = escape_sql_like_string(base)
         conds.append(AssetReference.file_path.like(escaped + "%", escape=esc))
     return conds
+
+
+def apply_tag_filters(
+    stmt: sa.sql.Select,
+    include_tags: Sequence[str] | None = None,
+    exclude_tags: Sequence[str] | None = None,
+) -> sa.sql.Select:
+    """include_tags: every tag must be present; exclude_tags: none may be present."""
+    include_tags = normalize_tags(include_tags)
+    exclude_tags = normalize_tags(exclude_tags)
+
+    if include_tags:
+        for tag_name in include_tags:
+            stmt = stmt.where(
+                exists().where(
+                    (AssetReferenceTag.asset_reference_id == AssetReference.id)
+                    & (AssetReferenceTag.tag_name == tag_name)
+                )
+            )
+
+    if exclude_tags:
+        stmt = stmt.where(
+            ~exists().where(
+                (AssetReferenceTag.asset_reference_id == AssetReference.id)
+                & (AssetReferenceTag.tag_name.in_(exclude_tags))
+            )
+        )
+    return stmt
+
+
+def apply_metadata_filter(
+    stmt: sa.sql.Select,
+    metadata_filter: dict | None = None,
+) -> sa.sql.Select:
+    """Apply filters using asset_reference_meta projection table."""
+    if not metadata_filter:
+        return stmt
+
+    def _exists_for_pred(key: str, *preds) -> sa.sql.ClauseElement:
+        return sa.exists().where(
+            AssetReferenceMeta.asset_reference_id == AssetReference.id,
+            AssetReferenceMeta.key == key,
+            *preds,
+        )
+
+    def _exists_clause_for_value(key: str, value) -> sa.sql.ClauseElement:
+        if value is None:
+            no_row_for_key = sa.not_(
+                sa.exists().where(
+                    AssetReferenceMeta.asset_reference_id == AssetReference.id,
+                    AssetReferenceMeta.key == key,
+                )
+            )
+            null_row = _exists_for_pred(
+                key,
+                AssetReferenceMeta.val_json.is_(None),
+                AssetReferenceMeta.val_str.is_(None),
+                AssetReferenceMeta.val_num.is_(None),
+                AssetReferenceMeta.val_bool.is_(None),
+            )
+            return sa.or_(no_row_for_key, null_row)
+
+        if isinstance(value, bool):
+            return _exists_for_pred(key, AssetReferenceMeta.val_bool == bool(value))
+        if isinstance(value, (int, float, Decimal)):
+            num = value if isinstance(value, Decimal) else Decimal(str(value))
+            return _exists_for_pred(key, AssetReferenceMeta.val_num == num)
+        if isinstance(value, str):
+            return _exists_for_pred(key, AssetReferenceMeta.val_str == value)
+        return _exists_for_pred(key, AssetReferenceMeta.val_json == value)
+
+    for k, v in metadata_filter.items():
+        if isinstance(v, list):
+            ors = [_exists_clause_for_value(k, elem) for elem in v]
+            if ors:
+                stmt = stmt.where(sa.or_(*ors))
+        else:
+            stmt = stmt.where(_exists_clause_for_value(k, v))
+    return stmt

app/assets/database/queries/tags.py

@@ -8,12 +8,15 @@ from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session
 
 from app.assets.database.models import (
+    Asset,
     AssetReference,
     AssetReferenceMeta,
     AssetReferenceTag,
     Tag,
 )
 from app.assets.database.queries.common import (
+    apply_metadata_filter,
+    apply_tag_filters,
     build_visible_owner_clause,
     iter_row_chunks,
 )
@@ -72,9 +75,9 @@ def get_reference_tags(session: Session, reference_id: str) -> list[str]:
         tag_name
         for (tag_name,) in (
             session.execute(
-                select(AssetReferenceTag.tag_name).where(
-                    AssetReferenceTag.asset_reference_id == reference_id
-                )
+                select(AssetReferenceTag.tag_name)
+                .where(AssetReferenceTag.asset_reference_id == reference_id)
+                .order_by(AssetReferenceTag.tag_name.asc())
             )
         ).all()
     ]
@@ -117,7 +120,7 @@ def set_reference_tags(
         )
         session.flush()
 
-    return SetTagsResult(added=to_add, removed=to_remove, total=desired)
+    return SetTagsResult(added=sorted(to_add), removed=sorted(to_remove), total=sorted(desired))
 
 
 def add_tags_to_reference(
@@ -272,6 +275,12 @@ def list_tags_with_usage(
         .select_from(AssetReferenceTag)
         .join(AssetReference, AssetReference.id == AssetReferenceTag.asset_reference_id)
         .where(build_visible_owner_clause(owner_id))
+        .where(
+            sa.or_(
+                AssetReference.is_missing == False,  # noqa: E712
+                AssetReferenceTag.tag_name == "missing",
+            )
+        )
         .where(AssetReference.deleted_at.is_(None))
         .group_by(AssetReferenceTag.tag_name)
         .subquery()
@@ -308,6 +317,12 @@ def list_tags_with_usage(
             select(AssetReferenceTag.tag_name)
             .join(AssetReference, AssetReference.id == AssetReferenceTag.asset_reference_id)
             .where(build_visible_owner_clause(owner_id))
+            .where(
+                sa.or_(
+                    AssetReference.is_missing == False,  # noqa: E712
+                    AssetReferenceTag.tag_name == "missing",
+                )
+            )
             .where(AssetReference.deleted_at.is_(None))
             .group_by(AssetReferenceTag.tag_name)
         )
@@ -320,6 +335,53 @@ def list_tags_with_usage(
     return rows_norm, int(total or 0)
 
 
+def list_tag_counts_for_filtered_assets(
+    session: Session,
+    owner_id: str = "",
+    include_tags: Sequence[str] | None = None,
+    exclude_tags: Sequence[str] | None = None,
+    name_contains: str | None = None,
+    metadata_filter: dict | None = None,
+    limit: int = 100,
+) -> dict[str, int]:
+    """Return tag counts for assets matching the given filters.
+
+    Uses the same filtering logic as list_references_page but returns
+    {tag_name: count} instead of paginated references.
+    """
+    # Build a subquery of matching reference IDs
+    ref_sq = (
+        select(AssetReference.id)
+        .join(Asset, Asset.id == AssetReference.asset_id)
+        .where(build_visible_owner_clause(owner_id))
+        .where(AssetReference.is_missing == False)  # noqa: E712
+        .where(AssetReference.deleted_at.is_(None))
+    )
+
+    if name_contains:
+        escaped, esc = escape_sql_like_string(name_contains)
+        ref_sq = ref_sq.where(AssetReference.name.ilike(f"%{escaped}%", escape=esc))
+
+    ref_sq = apply_tag_filters(ref_sq, include_tags, exclude_tags)
+    ref_sq = apply_metadata_filter(ref_sq, metadata_filter)
+    ref_sq = ref_sq.subquery()
+
+    # Count tags across those references
+    q = (
+        select(
+            AssetReferenceTag.tag_name,
+            func.count(AssetReferenceTag.asset_reference_id).label("cnt"),
+        )
+        .where(AssetReferenceTag.asset_reference_id.in_(select(ref_sq.c.id)))
+        .group_by(AssetReferenceTag.tag_name)
+        .order_by(func.count(AssetReferenceTag.asset_reference_id).desc(), AssetReferenceTag.tag_name.asc())
+        .limit(limit)
+    )
+
+    rows = session.execute(q).all()
+    return {tag_name: int(cnt) for tag_name, cnt in rows}
+
+
 def bulk_insert_tags_and_meta(
     session: Session,
     tag_rows: list[dict],

app/assets/scanner.py

@@ -18,7 +18,7 @@ from app.assets.database.queries import (
     mark_references_missing_outside_prefixes,
     reassign_asset_references,
     remove_missing_tag_for_asset_id,
-    set_reference_metadata,
+    set_reference_system_metadata,
     update_asset_hash_and_mime,
 )
 from app.assets.services.bulk_ingest import (
@@ -490,8 +490,8 @@ def enrich_asset(
             logging.warning("Failed to hash %s: %s", file_path, e)
 
     if extract_metadata and metadata:
-        user_metadata = metadata.to_user_metadata()
-        set_reference_metadata(session, reference_id, user_metadata)
+        system_metadata = metadata.to_user_metadata()
+        set_reference_system_metadata(session, reference_id, system_metadata)
 
     if full_hash:
         existing = get_asset_by_hash(session, full_hash)

app/assets/services/asset_management.py

@@ -16,10 +16,12 @@ from app.assets.database.queries import (
     get_reference_by_id,
     get_reference_with_owner_check,
     list_references_page,
+    list_all_file_paths_by_asset_id,
     list_references_by_asset_id,
     set_reference_metadata,
     set_reference_preview,
     set_reference_tags,
+    update_asset_hash_and_mime,
     update_reference_access_time,
     update_reference_name,
     update_reference_updated_at,
@@ -67,6 +69,8 @@ def update_asset_metadata(
     user_metadata: UserMetadata = None,
     tag_origin: str = "manual",
     owner_id: str = "",
+    mime_type: str | None = None,
+    preview_id: str | None = None,
 ) -> AssetDetailResult:
     with create_session() as session:
         ref = get_reference_with_owner_check(session, reference_id, owner_id)
@@ -103,6 +107,21 @@ def update_asset_metadata(
             )
             touched = True
 
+        if mime_type is not None:
+            updated = update_asset_hash_and_mime(
+                session, asset_id=ref.asset_id, mime_type=mime_type
+            )
+            if updated:
+                touched = True
+
+        if preview_id is not None:
+            set_reference_preview(
+                session,
+                reference_id=reference_id,
+                preview_reference_id=preview_id,
+            )
+            touched = True
+
         if touched and user_metadata is None:
             update_reference_updated_at(session, reference_id=reference_id)
 
@@ -159,11 +178,9 @@ def delete_asset_reference(
             session.commit()
             return True
 
-        # Orphaned asset - delete it and its files
-        refs = list_references_by_asset_id(session, asset_id=asset_id)
-        file_paths = [
-            r.file_path for r in (refs or []) if getattr(r, "file_path", None)
-        ]
+        # Orphaned asset - gather ALL file paths (including
+        # soft-deleted / missing refs) so their on-disk files get cleaned up.
+        file_paths = list_all_file_paths_by_asset_id(session, asset_id=asset_id)
         # Also include the just-deleted file path
         if file_path:
             file_paths.append(file_path)
@@ -185,7 +202,7 @@ def delete_asset_reference(
 
 def set_asset_preview(
     reference_id: str,
-    preview_asset_id: str | None = None,
+    preview_reference_id: str | None = None,
     owner_id: str = "",
 ) -> AssetDetailResult:
     with create_session() as session:
@@ -194,7 +211,7 @@ def set_asset_preview(
         set_reference_preview(
             session,
             reference_id=reference_id,
-            preview_asset_id=preview_asset_id,
+            preview_reference_id=preview_reference_id,
         )
 
         result = fetch_reference_asset_and_tags(
@@ -263,6 +280,47 @@ def list_assets_page(
         return ListAssetsResult(items=items, total=total)
 
 
+def resolve_hash_to_path(
+    asset_hash: str,
+    owner_id: str = "",
+) -> DownloadResolutionResult | None:
+    """Resolve a blake3 hash to an on-disk file path.
+
+    Only references visible to *owner_id* are considered (owner-less
+    references are always visible).
+
+    Returns a DownloadResolutionResult with abs_path, content_type, and
+    download_name, or None if no asset or live path is found.
+    """
+    with create_session() as session:
+        asset = queries_get_asset_by_hash(session, asset_hash)
+        if not asset:
+            return None
+        refs = list_references_by_asset_id(session, asset_id=asset.id)
+        visible = [
+            r for r in refs
+            if r.owner_id == "" or r.owner_id == owner_id
+        ]
+        abs_path = select_best_live_path(visible)
+        if not abs_path:
+            return None
+        display_name = os.path.basename(abs_path)
+        for ref in visible:
+            if ref.file_path == abs_path and ref.name:
+                display_name = ref.name
+                break
+        ctype = (
+            asset.mime_type
+            or mimetypes.guess_type(display_name)[0]
+            or "application/octet-stream"
+        )
+    return DownloadResolutionResult(
+        abs_path=abs_path,
+        content_type=ctype,
+        download_name=display_name,
+    )
+
+
 def resolve_asset_for_download(
     reference_id: str,
     owner_id: str = "",

app/assets/services/ingest.py

@@ -11,13 +11,14 @@ from app.assets.database.queries import (
     add_tags_to_reference,
     fetch_reference_and_asset,
     get_asset_by_hash,
-    get_existing_asset_ids,
     get_reference_by_file_path,
     get_reference_tags,
     get_or_create_reference,
+    reference_exists,
     remove_missing_tag_for_asset_id,
     set_reference_metadata,
     set_reference_tags,
+    update_asset_hash_and_mime,
     upsert_asset,
     upsert_reference,
     validate_tags_exist,
@@ -26,6 +27,7 @@ from app.assets.helpers import normalize_tags
 from app.assets.services.file_utils import get_size_and_mtime_ns
 from app.assets.services.path_utils import (
     compute_relative_filename,
+    get_name_and_tags_from_asset_path,
     resolve_destination_from_tags,
     validate_path_within_base,
 )
@@ -65,7 +67,7 @@ def _ingest_file_from_path(
 
     with create_session() as session:
         if preview_id:
-            if preview_id not in get_existing_asset_ids(session, [preview_id]):
+            if not reference_exists(session, preview_id):
                 preview_id = None
 
         asset, asset_created, asset_updated = upsert_asset(
@@ -135,6 +137,8 @@ def _register_existing_asset(
     tags: list[str] | None = None,
     tag_origin: str = "manual",
     owner_id: str = "",
+    mime_type: str | None = None,
+    preview_id: str | None = None,
 ) -> RegisterAssetResult:
     user_metadata = user_metadata or {}
 
@@ -143,14 +147,25 @@ def _register_existing_asset(
         if not asset:
             raise ValueError(f"No asset with hash {asset_hash}")
 
+        if mime_type and not asset.mime_type:
+            update_asset_hash_and_mime(session, asset_id=asset.id, mime_type=mime_type)
+
+        if preview_id:
+            if not reference_exists(session, preview_id):
+                preview_id = None
+
         ref, ref_created = get_or_create_reference(
             session,
             asset_id=asset.id,
             owner_id=owner_id,
             name=name,
+            preview_id=preview_id,
         )
 
         if not ref_created:
+            if preview_id and ref.preview_id != preview_id:
+                ref.preview_id = preview_id
+
             tag_names = get_reference_tags(session, reference_id=ref.id)
             result = RegisterAssetResult(
                 ref=extract_reference_data(ref),
@@ -242,6 +257,8 @@ def upload_from_temp_path(
     client_filename: str | None = None,
     owner_id: str = "",
     expected_hash: str | None = None,
+    mime_type: str | None = None,
+    preview_id: str | None = None,
 ) -> UploadResult:
     try:
         digest, _ = hashing.compute_blake3_hash(temp_path)
@@ -270,6 +287,8 @@ def upload_from_temp_path(
             tags=tags or [],
             tag_origin="manual",
             owner_id=owner_id,
+            mime_type=mime_type,
+            preview_id=preview_id,
         )
         return UploadResult(
             ref=result.ref,
@@ -291,7 +310,7 @@ def upload_from_temp_path(
     dest_abs = os.path.abspath(os.path.join(dest_dir, hashed_basename))
     validate_path_within_base(dest_abs, base_dir)
 
-    content_type = (
+    content_type = mime_type or (
         mimetypes.guess_type(os.path.basename(src_for_ext), strict=False)[0]
         or mimetypes.guess_type(hashed_basename, strict=False)[0]
         or "application/octet-stream"
@@ -315,7 +334,7 @@ def upload_from_temp_path(
         mime_type=content_type,
         info_name=_sanitize_filename(name or client_filename, fallback=digest),
         owner_id=owner_id,
-        preview_id=None,
+        preview_id=preview_id,
         user_metadata=user_metadata or {},
         tags=tags,
         tag_origin="manual",
@@ -342,30 +361,99 @@ def upload_from_temp_path(
     )
 
 
+def register_file_in_place(
+    abs_path: str,
+    name: str,
+    tags: list[str],
+    owner_id: str = "",
+    mime_type: str | None = None,
+) -> UploadResult:
+    """Register an already-saved file in the asset database without moving it.
+
+    Tags are derived from the filesystem path (root category + subfolder names),
+    merged with any caller-provided tags, matching the behavior of the scanner.
+    If the path is not under a known root, only the caller-provided tags are used.
+    """
+    try:
+        _, path_tags = get_name_and_tags_from_asset_path(abs_path)
+    except ValueError:
+        path_tags = []
+    merged_tags = normalize_tags([*path_tags, *tags])
+
+    try:
+        digest, _ = hashing.compute_blake3_hash(abs_path)
+    except ImportError as e:
+        raise DependencyMissingError(str(e))
+    except Exception as e:
+        raise RuntimeError(f"failed to hash file: {e}")
+    asset_hash = "blake3:" + digest
+
+    size_bytes, mtime_ns = get_size_and_mtime_ns(abs_path)
+    content_type = mime_type or (
+        mimetypes.guess_type(abs_path, strict=False)[0]
+        or "application/octet-stream"
+    )
+
+    ingest_result = _ingest_file_from_path(
+        abs_path=abs_path,
+        asset_hash=asset_hash,
+        size_bytes=size_bytes,
+        mtime_ns=mtime_ns,
+        mime_type=content_type,
+        info_name=_sanitize_filename(name, fallback=digest),
+        owner_id=owner_id,
+        tags=merged_tags,
+        tag_origin="upload",
+        require_existing_tags=False,
+    )
+    reference_id = ingest_result.reference_id
+    if not reference_id:
+        raise RuntimeError("failed to create asset reference")
+
+    with create_session() as session:
+        pair = fetch_reference_and_asset(
+            session, reference_id=reference_id, owner_id=owner_id
+        )
+        if not pair:
+            raise RuntimeError("inconsistent DB state after ingest")
+        ref, asset = pair
+        tag_names = get_reference_tags(session, reference_id=ref.id)
+
+    return UploadResult(
+        ref=extract_reference_data(ref),
+        asset=extract_asset_data(asset),
+        tags=tag_names,
+        created_new=ingest_result.asset_created,
+    )
+
+
 def create_from_hash(
     hash_str: str,
     name: str,
     tags: list[str] | None = None,
     user_metadata: dict | None = None,
     owner_id: str = "",
+    mime_type: str | None = None,
+    preview_id: str | None = None,
 ) -> UploadResult | None:
     canonical = hash_str.strip().lower()
 
-    with create_session() as session:
-        asset = get_asset_by_hash(session, asset_hash=canonical)
-        if not asset:
-            return None
-
-    result = _register_existing_asset(
-        asset_hash=canonical,
-        name=_sanitize_filename(
-            name, fallback=canonical.split(":", 1)[1] if ":" in canonical else canonical
-        ),
-        user_metadata=user_metadata or {},
-        tags=tags or [],
-        tag_origin="manual",
-        owner_id=owner_id,
-    )
+    try:
+        result = _register_existing_asset(
+            asset_hash=canonical,
+            name=_sanitize_filename(
+                name, fallback=canonical.split(":", 1)[1] if ":" in canonical else canonical
+            ),
+            user_metadata=user_metadata or {},
+            tags=tags or [],
+            tag_origin="manual",
+            owner_id=owner_id,
+            mime_type=mime_type,
+            preview_id=preview_id,
+        )
+    except ValueError:
+        logging.warning("create_from_hash: no asset found for hash %s", canonical)
+        return None
 
     return UploadResult(
         ref=result.ref,

app/assets/services/schemas.py

@@ -25,7 +25,9 @@ class ReferenceData:
     preview_id: str | None
     created_at: datetime
     updated_at: datetime
-    last_access_time: datetime | None
+    system_metadata: dict[str, Any] | None = None
+    prompt_id: str | None = None
+    last_access_time: datetime | None = None
 
 
 @dataclass(frozen=True)
@@ -93,6 +95,8 @@ def extract_reference_data(ref: AssetReference) -> ReferenceData:
         file_path=ref.file_path,
         user_metadata=ref.user_metadata,
         preview_id=ref.preview_id,
+        system_metadata=ref.system_metadata,
+        prompt_id=ref.prompt_id,
         created_at=ref.created_at,
         updated_at=ref.updated_at,
         last_access_time=ref.last_access_time,

app/assets/services/tagging.py

@@ -1,3 +1,5 @@
+from typing import Sequence
+
 from app.assets.database.queries import (
     AddTagsResult,
     RemoveTagsResult,
@@ -6,6 +8,7 @@ from app.assets.database.queries import (
     list_tags_with_usage,
     remove_tags_from_reference,
 )
+from app.assets.database.queries.tags import list_tag_counts_for_filtered_assets
 from app.assets.services.schemas import TagUsage
 from app.database.db import create_session
 
@@ -73,3 +76,23 @@ def list_tags(
         )
 
     return [TagUsage(name, tag_type, count) for name, tag_type, count in rows], total
+
+
+def list_tag_histogram(
+    owner_id: str = "",
+    include_tags: Sequence[str] | None = None,
+    exclude_tags: Sequence[str] | None = None,
+    name_contains: str | None = None,
+    metadata_filter: dict | None = None,
+    limit: int = 100,
+) -> dict[str, int]:
+    with create_session() as session:
+        return list_tag_counts_for_filtered_assets(
+            session,
+            owner_id=owner_id,
+            include_tags=include_tags,
+            exclude_tags=exclude_tags,
+            name_contains=name_contains,
+            metadata_filter=metadata_filter,
+            limit=limit,
+        )

app/database/models.py

@@ -1,9 +1,18 @@
 from typing import Any
 from datetime import datetime
+from sqlalchemy import MetaData
 from sqlalchemy.orm import DeclarativeBase
 
+NAMING_CONVENTION = {
+    "ix": "ix_%(table_name)s_%(column_0_N_name)s",
+    "uq": "uq_%(table_name)s_%(column_0_N_name)s",
+    "ck": "ck_%(table_name)s_%(constraint_name)s",
+    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
+    "pk": "pk_%(table_name)s",
+}
+
 class Base(DeclarativeBase):
-    pass
+    metadata = MetaData(naming_convention=NAMING_CONVENTION)
 
 def to_dict(obj: Any, include_none: bool = False) -> dict[str, Any]:
     fields = obj.__table__.columns.keys()

middleware/cache_middleware.py

@@ -32,7 +32,7 @@ async def cache_control(
     )
 
     if request.path.endswith(".js") or request.path.endswith(".css") or is_entry_point:
-        response.headers.setdefault("Cache-Control", "no-store")
+        response.headers.setdefault("Cache-Control", "no-cache")
         return response
 
     # Early return for non-image files - no cache headers needed

server.py

@@ -35,6 +35,8 @@ from app.frontend_management import FrontendManager, parse_version
 from comfy_api.internal import _ComfyNodeInternal
 from app.assets.seeder import asset_seeder
 from app.assets.api.routes import register_assets_routes
+from app.assets.services.ingest import register_file_in_place
+from app.assets.services.asset_management import resolve_hash_to_path
 
 from app.user_manager import UserManager
 from app.model_manager import ModelFileManager
@@ -310,7 +312,7 @@ class PromptServer():
         @routes.get("/")
         async def get_root(request):
             response = web.FileResponse(os.path.join(self.web_root, "index.html"))
-            response.headers['Cache-Control'] = 'no-store, must-revalidate'
+            response.headers['Cache-Control'] = 'no-cache'
             response.headers["Pragma"] = "no-cache"
             response.headers["Expires"] = "0"
             return response
@@ -419,7 +421,24 @@ class PromptServer():
                         with open(filepath, "wb") as f:
                             f.write(image.file.read())
 
-                return web.json_response({"name" : filename, "subfolder": subfolder, "type": image_upload_type})
+                resp = {"name" : filename, "subfolder": subfolder, "type": image_upload_type}
+
+                if args.enable_assets:
+                    try:
+                        tag = image_upload_type if image_upload_type in ("input", "output") else "input"
+                        result = register_file_in_place(abs_path=filepath, name=filename, tags=[tag])
+                        resp["asset"] = {
+                            "id": result.ref.id,
+                            "name": result.ref.name,
+                            "asset_hash": result.asset.hash if result.asset else None,
+                            "size": result.asset.size_bytes if result.asset else None,
+                            "mime_type": result.asset.mime_type if result.asset else None,
+                            "tags": result.tags,
+                        }
+                    except Exception:
+                        logging.warning("Failed to register uploaded image as asset", exc_info=True)
+
+                return web.json_response(resp)
             else:
                 return web.Response(status=400)
 
@@ -479,30 +498,43 @@ class PromptServer():
         async def view_image(request):
             if "filename" in request.rel_url.query:
                 filename = request.rel_url.query["filename"]
-                filename, output_dir = folder_paths.annotated_filepath(filename)
 
-                if not filename:
-                    return web.Response(status=400)
+                # The frontend's LoadImage combo widget uses asset_hash values
+                # (e.g. "blake3:...") as widget values. When litegraph renders the
+                # node preview, it constructs /view?filename=<asset_hash>, so this
+                # endpoint must resolve blake3 hashes to their on-disk file paths.
+                if filename.startswith("blake3:"):
+                    owner_id = self.user_manager.get_request_user_id(request)
+                    result = resolve_hash_to_path(filename, owner_id=owner_id)
+                    if result is None:
+                        return web.Response(status=404)
+                    file, filename, resolved_content_type = result.abs_path, result.download_name, result.content_type
+                else:
+                    resolved_content_type = None
+                    filename, output_dir = folder_paths.annotated_filepath(filename)
 
-                # validation for security: prevent accessing arbitrary path
-                if filename[0] == '/' or '..' in filename:
-                    return web.Response(status=400)
+                    if not filename:
+                        return web.Response(status=400)
 
-                if output_dir is None:
-                    type = request.rel_url.query.get("type", "output")
-                    output_dir = folder_paths.get_directory_by_type(type)
+                    # validation for security: prevent accessing arbitrary path
+                    if filename[0] == '/' or '..' in filename:
+                        return web.Response(status=400)
 
-                if output_dir is None:
-                    return web.Response(status=400)
+                    if output_dir is None:
+                        type = request.rel_url.query.get("type", "output")
+                        output_dir = folder_paths.get_directory_by_type(type)
 
-                if "subfolder" in request.rel_url.query:
-                    full_output_dir = os.path.join(output_dir, request.rel_url.query["subfolder"])
-                    if os.path.commonpath((os.path.abspath(full_output_dir), output_dir)) != output_dir:
-                        return web.Response(status=403)
-                    output_dir = full_output_dir
+                    if output_dir is None:
+                        return web.Response(status=400)
 
-                filename = os.path.basename(filename)
-                file = os.path.join(output_dir, filename)
+                    if "subfolder" in request.rel_url.query:
+                        full_output_dir = os.path.join(output_dir, request.rel_url.query["subfolder"])
+                        if os.path.commonpath((os.path.abspath(full_output_dir), output_dir)) != output_dir:
+                            return web.Response(status=403)
+                        output_dir = full_output_dir
+
+                    filename = os.path.basename(filename)
+                    file = os.path.join(output_dir, filename)
 
                 if os.path.isfile(file):
                     if 'preview' in request.rel_url.query:
@@ -562,8 +594,13 @@ class PromptServer():
                             return web.Response(body=alpha_buffer.read(), content_type='image/png',
                                                 headers={"Content-Disposition": f"filename=\"{filename}\""})
                     else:
-                        # Get content type from mimetype, defaulting to 'application/octet-stream'
-                        content_type = mimetypes.guess_type(filename)[0] or 'application/octet-stream'
+                        # Use the content type from asset resolution if available,
+                        # otherwise guess from the filename.
+                        content_type = (
+                            resolved_content_type
+                            or mimetypes.guess_type(filename)[0]
+                            or 'application/octet-stream'
+                        )
 
                         # For security, force certain mimetypes to download instead of display
                         if content_type in {'text/html', 'text/html-sandboxed', 'application/xhtml+xml', 'text/javascript', 'text/css'}:

tests-unit/app_test/test_migrations.py

@@ -0,0 +1,57 @@
+"""Test that Alembic migrations run cleanly on a file-backed SQLite DB.
+
+This catches problems like unnamed FK constraints that prevent batch-mode
+drop_constraint from working on real SQLite files (see MB-2).
+
+Migrations 0001 and 0002 are already shipped, so we only exercise
+upgrade/downgrade for 0003+.
+"""
+
+import os
+
+import pytest
+from alembic import command
+from alembic.config import Config
+
+
+# Oldest shipped revision — we upgrade to here as a baseline and never
+# downgrade past it.
+_BASELINE = "0002_merge_to_asset_references"
+
+
+def _make_config(db_path: str) -> Config:
+    root = os.path.join(os.path.dirname(__file__), "../..")
+    config_path = os.path.abspath(os.path.join(root, "alembic.ini"))
+    scripts_path = os.path.abspath(os.path.join(root, "alembic_db"))
+
+    cfg = Config(config_path)
+    cfg.set_main_option("script_location", scripts_path)
+    cfg.set_main_option("sqlalchemy.url", f"sqlite:///{db_path}")
+    return cfg
+
+
+@pytest.fixture
+def migration_db(tmp_path):
+    """Yield an alembic Config pre-upgraded to the baseline revision."""
+    db_path = str(tmp_path / "test_migration.db")
+    cfg = _make_config(db_path)
+    command.upgrade(cfg, _BASELINE)
+    yield cfg
+
+
+def test_upgrade_to_head(migration_db):
+    """Upgrade from baseline to head must succeed on a file-backed DB."""
+    command.upgrade(migration_db, "head")
+
+
+def test_downgrade_to_baseline(migration_db):
+    """Upgrade to head then downgrade back to baseline."""
+    command.upgrade(migration_db, "head")
+    command.downgrade(migration_db, _BASELINE)
+
+
+def test_upgrade_downgrade_cycle(migration_db):
+    """Full cycle: upgrade → downgrade → upgrade again."""
+    command.upgrade(migration_db, "head")
+    command.downgrade(migration_db, _BASELINE)
+    command.upgrade(migration_db, "head")

tests-unit/assets_test/queries/test_asset.py

@@ -10,6 +10,7 @@ from app.assets.database.queries import (
     get_asset_by_hash,
     upsert_asset,
     bulk_insert_assets,
+    update_asset_hash_and_mime,
 )
 
 
@@ -142,3 +143,45 @@ class TestBulkInsertAssets:
         session.commit()
 
         assert session.query(Asset).count() == 200
+
+
+class TestMimeTypeImmutability:
+    """mime_type on Asset is write-once: set on first ingest, never overwritten."""
+
+    @pytest.mark.parametrize(
+        "initial_mime,second_mime,expected_mime",
+        [
+            ("image/png", "image/jpeg", "image/png"),
+            (None, "image/png", "image/png"),
+        ],
+        ids=["preserves_existing", "fills_null"],
+    )
+    def test_upsert_mime_immutability(self, session: Session, initial_mime, second_mime, expected_mime):
+        h = f"blake3:upsert_{initial_mime}_{second_mime}"
+        upsert_asset(session, asset_hash=h, size_bytes=100, mime_type=initial_mime)
+        session.commit()
+
+        asset, created, _ = upsert_asset(session, asset_hash=h, size_bytes=100, mime_type=second_mime)
+        assert created is False
+        assert asset.mime_type == expected_mime
+
+    @pytest.mark.parametrize(
+        "initial_mime,update_mime,update_hash,expected_mime,expected_hash",
+        [
+            (None, "image/png", None, "image/png", "blake3:upd0"),
+            ("image/png", "image/jpeg", None, "image/png", "blake3:upd1"),
+            ("image/png", "image/jpeg", "blake3:upd2_new", "image/png", "blake3:upd2_new"),
+        ],
+        ids=["fills_null", "preserves_existing", "hash_updates_mime_locked"],
+    )
+    def test_update_asset_hash_and_mime_immutability(
+        self, session: Session, initial_mime, update_mime, update_hash, expected_mime, expected_hash,
+    ):
+        h = expected_hash.removesuffix("_new")
+        asset = Asset(hash=h, size_bytes=100, mime_type=initial_mime)
+        session.add(asset)
+        session.flush()
+
+        update_asset_hash_and_mime(session, asset_id=asset.id, mime_type=update_mime, asset_hash=update_hash)
+        assert asset.mime_type == expected_mime
+        assert asset.hash == expected_hash

tests-unit/assets_test/queries/test_asset_info.py

@@ -242,22 +242,24 @@ class TestSetReferencePreview:
         asset = _make_asset(session, "hash1")
         preview_asset = _make_asset(session, "preview_hash")
         ref = _make_reference(session, asset)
+        preview_ref = _make_reference(session, preview_asset, name="preview.png")
         session.commit()
 
-        set_reference_preview(session, reference_id=ref.id, preview_asset_id=preview_asset.id)
+        set_reference_preview(session, reference_id=ref.id, preview_reference_id=preview_ref.id)
         session.commit()
 
         session.refresh(ref)
-        assert ref.preview_id == preview_asset.id
+        assert ref.preview_id == preview_ref.id
 
     def test_clears_preview(self, session: Session):
         asset = _make_asset(session, "hash1")
         preview_asset = _make_asset(session, "preview_hash")
         ref = _make_reference(session, asset)
-        ref.preview_id = preview_asset.id
+        preview_ref = _make_reference(session, preview_asset, name="preview.png")
+        ref.preview_id = preview_ref.id
         session.commit()
 
-        set_reference_preview(session, reference_id=ref.id, preview_asset_id=None)
+        set_reference_preview(session, reference_id=ref.id, preview_reference_id=None)
         session.commit()
 
         session.refresh(ref)
@@ -265,15 +267,15 @@ class TestSetReferencePreview:
 
     def test_raises_for_nonexistent_reference(self, session: Session):
         with pytest.raises(ValueError, match="not found"):
-            set_reference_preview(session, reference_id="nonexistent", preview_asset_id=None)
+            set_reference_preview(session, reference_id="nonexistent", preview_reference_id=None)
 
     def test_raises_for_nonexistent_preview(self, session: Session):
         asset = _make_asset(session, "hash1")
         ref = _make_reference(session, asset)
         session.commit()
 
-        with pytest.raises(ValueError, match="Preview Asset"):
-            set_reference_preview(session, reference_id=ref.id, preview_asset_id="nonexistent")
+        with pytest.raises(ValueError, match="Preview AssetReference"):
+            set_reference_preview(session, reference_id=ref.id, preview_reference_id="nonexistent")
 
 
 class TestInsertReference:
@@ -351,13 +353,14 @@ class TestUpdateReferenceTimestamps:
         asset = _make_asset(session, "hash1")
         preview_asset = _make_asset(session, "preview_hash")
         ref = _make_reference(session, asset)
+        preview_ref = _make_reference(session, preview_asset, name="preview.png")
         session.commit()
 
-        update_reference_timestamps(session, ref, preview_id=preview_asset.id)
+        update_reference_timestamps(session, ref, preview_id=preview_ref.id)
         session.commit()
 
         session.refresh(ref)
-        assert ref.preview_id == preview_asset.id
+        assert ref.preview_id == preview_ref.id
 
 
 class TestSetReferenceMetadata:

tests-unit/assets_test/queries/test_metadata.py

@@ -20,6 +20,7 @@ def _make_reference(
     asset: Asset,
     name: str,
     metadata: dict | None = None,
+    system_metadata: dict | None = None,
 ) -> AssetReference:
     now = get_utc_now()
     ref = AssetReference(
@@ -27,6 +28,7 @@ def _make_reference(
         name=name,
         asset_id=asset.id,
         user_metadata=metadata,
+        system_metadata=system_metadata,
         created_at=now,
         updated_at=now,
         last_access_time=now,
@@ -34,8 +36,10 @@ def _make_reference(
     session.add(ref)
     session.flush()
 
-    if metadata:
-        for key, val in metadata.items():
+    # Build merged projection: {**system_metadata, **user_metadata}
+    merged = {**(system_metadata or {}), **(metadata or {})}
+    if merged:
+        for key, val in merged.items():
             for row in convert_metadata_to_rows(key, val):
                 meta_row = AssetReferenceMeta(
                     asset_reference_id=ref.id,
@@ -182,3 +186,46 @@ class TestMetadataFilterEmptyDict:
 
         refs, _, total = list_references_page(session, metadata_filter={})
         assert total == 2
+
+
+class TestSystemMetadataProjection:
+    """Tests for system_metadata merging into the filter projection."""
+
+    def test_system_metadata_keys_are_filterable(self, session: Session):
+        """system_metadata keys should appear in the merged projection."""
+        asset = _make_asset(session, "hash1")
+        _make_reference(
+            session, asset, "with_sys",
+            system_metadata={"source": "scanner"},
+        )
+        _make_reference(session, asset, "without_sys")
+        session.commit()
+
+        refs, _, total = list_references_page(
+            session, metadata_filter={"source": "scanner"}
+        )
+        assert total == 1
+        assert refs[0].name == "with_sys"
+
+    def test_user_metadata_overrides_system_metadata(self, session: Session):
+        """user_metadata should win when both have the same key."""
+        asset = _make_asset(session, "hash1")
+        _make_reference(
+            session, asset, "overridden",
+            metadata={"origin": "user_upload"},
+            system_metadata={"origin": "auto_scan"},
+        )
+        session.commit()
+
+        # Should match the user value, not the system value
+        refs, _, total = list_references_page(
+            session, metadata_filter={"origin": "user_upload"}
+        )
+        assert total == 1
+        assert refs[0].name == "overridden"
+
+        # Should NOT match the system value (it was overridden)
+        refs, _, total = list_references_page(
+            session, metadata_filter={"origin": "auto_scan"}
+        )
+        assert total == 0

tests-unit/assets_test/services/test_asset_management.py

@@ -11,6 +11,7 @@ from app.assets.services import (
     delete_asset_reference,
     set_asset_preview,
 )
+from app.assets.services.asset_management import resolve_hash_to_path
 
 
 def _make_asset(session: Session, hash_val: str = "blake3:test", size: int = 1024) -> Asset:
@@ -219,31 +220,33 @@ class TestSetAssetPreview:
         asset = _make_asset(session, hash_val="blake3:main")
         preview_asset = _make_asset(session, hash_val="blake3:preview")
         ref = _make_reference(session, asset)
+        preview_ref = _make_reference(session, preview_asset, name="preview.png")
         ref_id = ref.id
-        preview_id = preview_asset.id
+        preview_ref_id = preview_ref.id
         session.commit()
 
         set_asset_preview(
             reference_id=ref_id,
-            preview_asset_id=preview_id,
+            preview_reference_id=preview_ref_id,
         )
 
         # Verify by re-fetching from DB
         session.expire_all()
         updated_ref = session.get(AssetReference, ref_id)
-        assert updated_ref.preview_id == preview_id
+        assert updated_ref.preview_id == preview_ref_id
 
     def test_clears_preview(self, mock_create_session, session: Session):
         asset = _make_asset(session)
         preview_asset = _make_asset(session, hash_val="blake3:preview")
         ref = _make_reference(session, asset)
-        ref.preview_id = preview_asset.id
+        preview_ref = _make_reference(session, preview_asset, name="preview.png")
+        ref.preview_id = preview_ref.id
         ref_id = ref.id
         session.commit()
 
         set_asset_preview(
             reference_id=ref_id,
-            preview_asset_id=None,
+            preview_reference_id=None,
         )
 
         # Verify by re-fetching from DB
@@ -263,6 +266,45 @@ class TestSetAssetPreview:
         with pytest.raises(PermissionError, match="not owner"):
             set_asset_preview(
                 reference_id=ref.id,
-                preview_asset_id=None,
+                preview_reference_id=None,
                 owner_id="user2",
             )
+
+
+class TestResolveHashToPath:
+    def test_returns_none_for_unknown_hash(self, mock_create_session):
+        result = resolve_hash_to_path("blake3:" + "a" * 64)
+        assert result is None
+
+    @pytest.mark.parametrize(
+        "ref_owner, query_owner, expect_found",
+        [
+            ("user1", "user1", True),
+            ("user1", "user2", False),
+            ("", "anyone", True),
+            ("", "", True),
+        ],
+        ids=[
+            "owner_sees_own_ref",
+            "other_owner_blocked",
+            "ownerless_visible_to_anyone",
+            "ownerless_visible_to_empty",
+        ],
+    )
+    def test_owner_visibility(
+        self, ref_owner, query_owner, expect_found,
+        mock_create_session, session: Session, temp_dir,
+    ):
+        f = temp_dir / "file.bin"
+        f.write_bytes(b"data")
+        asset = _make_asset(session, hash_val="blake3:" + "b" * 64)
+        ref = _make_reference(session, asset, name="file.bin", owner_id=ref_owner)
+        ref.file_path = str(f)
+        session.commit()
+
+        result = resolve_hash_to_path(asset.hash, owner_id=query_owner)
+        if expect_found:
+            assert result is not None
+            assert result.abs_path == str(f)
+        else:
+            assert result is None

tests-unit/assets_test/services/test_ingest.py

@@ -113,11 +113,19 @@ class TestIngestFileFromPath:
         file_path = temp_dir / "with_preview.bin"
         file_path.write_bytes(b"data")
 
-        # Create a preview asset first
+        # Create a preview asset and reference
         preview_asset = Asset(hash="blake3:preview", size_bytes=100)
         session.add(preview_asset)
+        session.flush()
+        from app.assets.helpers import get_utc_now
+        now = get_utc_now()
+        preview_ref = AssetReference(
+            asset_id=preview_asset.id, name="preview.png", owner_id="",
+            created_at=now, updated_at=now, last_access_time=now,
+        )
+        session.add(preview_ref)
         session.commit()
-        preview_id = preview_asset.id
+        preview_id = preview_ref.id
 
         result = _ingest_file_from_path(
             abs_path=str(file_path),

tests-unit/assets_test/services/test_tag_histogram.py

@@ -0,0 +1,123 @@
+"""Tests for list_tag_histogram service function."""
+from sqlalchemy.orm import Session
+
+from app.assets.database.models import Asset, AssetReference
+from app.assets.database.queries import ensure_tags_exist, add_tags_to_reference
+from app.assets.helpers import get_utc_now
+from app.assets.services.tagging import list_tag_histogram
+
+
+def _make_asset(session: Session, hash_val: str = "blake3:test") -> Asset:
+    asset = Asset(hash=hash_val, size_bytes=1024)
+    session.add(asset)
+    session.flush()
+    return asset
+
+
+def _make_reference(
+    session: Session,
+    asset: Asset,
+    name: str = "test",
+    owner_id: str = "",
+) -> AssetReference:
+    now = get_utc_now()
+    ref = AssetReference(
+        owner_id=owner_id,
+        name=name,
+        asset_id=asset.id,
+        created_at=now,
+        updated_at=now,
+        last_access_time=now,
+    )
+    session.add(ref)
+    session.flush()
+    return ref
+
+
+class TestListTagHistogram:
+    def test_returns_counts_for_all_tags(self, mock_create_session, session: Session):
+        ensure_tags_exist(session, ["alpha", "beta"])
+        a1 = _make_asset(session, "blake3:aaa")
+        r1 = _make_reference(session, a1, name="r1")
+        add_tags_to_reference(session, reference_id=r1.id, tags=["alpha", "beta"])
+
+        a2 = _make_asset(session, "blake3:bbb")
+        r2 = _make_reference(session, a2, name="r2")
+        add_tags_to_reference(session, reference_id=r2.id, tags=["alpha"])
+        session.commit()
+
+        result = list_tag_histogram()
+
+        assert result["alpha"] == 2
+        assert result["beta"] == 1
+
+    def test_empty_when_no_assets(self, mock_create_session, session: Session):
+        ensure_tags_exist(session, ["unused"])
+        session.commit()
+
+        result = list_tag_histogram()
+
+        assert result == {}
+
+    def test_include_tags_filter(self, mock_create_session, session: Session):
+        ensure_tags_exist(session, ["models", "loras", "input"])
+        a1 = _make_asset(session, "blake3:aaa")
+        r1 = _make_reference(session, a1, name="r1")
+        add_tags_to_reference(session, reference_id=r1.id, tags=["models", "loras"])
+
+        a2 = _make_asset(session, "blake3:bbb")
+        r2 = _make_reference(session, a2, name="r2")
+        add_tags_to_reference(session, reference_id=r2.id, tags=["input"])
+        session.commit()
+
+        result = list_tag_histogram(include_tags=["models"])
+
+        # Only r1 has "models", so only its tags appear
+        assert "models" in result
+        assert "loras" in result
+        assert "input" not in result
+
+    def test_exclude_tags_filter(self, mock_create_session, session: Session):
+        ensure_tags_exist(session, ["models", "loras", "input"])
+        a1 = _make_asset(session, "blake3:aaa")
+        r1 = _make_reference(session, a1, name="r1")
+        add_tags_to_reference(session, reference_id=r1.id, tags=["models", "loras"])
+
+        a2 = _make_asset(session, "blake3:bbb")
+        r2 = _make_reference(session, a2, name="r2")
+        add_tags_to_reference(session, reference_id=r2.id, tags=["input"])
+        session.commit()
+
+        result = list_tag_histogram(exclude_tags=["models"])
+
+        # r1 excluded, only r2's tags remain
+        assert "input" in result
+        assert "loras" not in result
+
+    def test_name_contains_filter(self, mock_create_session, session: Session):
+        ensure_tags_exist(session, ["alpha", "beta"])
+        a1 = _make_asset(session, "blake3:aaa")
+        r1 = _make_reference(session, a1, name="my_model.safetensors")
+        add_tags_to_reference(session, reference_id=r1.id, tags=["alpha"])
+
+        a2 = _make_asset(session, "blake3:bbb")
+        r2 = _make_reference(session, a2, name="picture.png")
+        add_tags_to_reference(session, reference_id=r2.id, tags=["beta"])
+        session.commit()
+
+        result = list_tag_histogram(name_contains="model")
+
+        assert "alpha" in result
+        assert "beta" not in result
+
+    def test_limit_caps_results(self, mock_create_session, session: Session):
+        tags = [f"tag{i}" for i in range(10)]
+        ensure_tags_exist(session, tags)
+        a = _make_asset(session, "blake3:aaa")
+        r = _make_reference(session, a, name="r1")
+        add_tags_to_reference(session, reference_id=r.id, tags=tags)
+        session.commit()
+
+        result = list_tag_histogram(limit=3)
+
+        assert len(result) == 3

tests-unit/assets_test/test_uploads.py

@@ -243,6 +243,15 @@ def test_upload_tags_traversal_guard(http: requests.Session, api_base: str):
     assert body["error"]["code"] in ("BAD_REQUEST", "INVALID_BODY")
 
 
+def test_upload_empty_tags_rejected(http: requests.Session, api_base: str):
+    files = {"file": ("notags.bin", b"A" * 64, "application/octet-stream")}
+    form = {"tags": json.dumps([]), "name": "notags.bin", "user_metadata": json.dumps({})}
+    r = http.post(api_base + "/api/assets", data=form, files=files, timeout=120)
+    body = r.json()
+    assert r.status_code == 400
+    assert body["error"]["code"] == "INVALID_BODY"
+
+
 @pytest.mark.parametrize("root", ["input", "output"])
 def test_duplicate_upload_same_display_name_does_not_clobber(
     root: str,

tests-unit/server_test/test_cache_control.py

@@ -28,31 +28,31 @@ CACHE_SCENARIOS = [
     },
     # JavaScript/CSS scenarios
     {
-        "name": "js_no_store",
+        "name": "js_no_cache",
         "path": "/script.js",
         "status": 200,
-        "expected_cache": "no-store",
+        "expected_cache": "no-cache",
         "should_have_header": True,
     },
     {
-        "name": "css_no_store",
+        "name": "css_no_cache",
         "path": "/styles.css",
         "status": 200,
-        "expected_cache": "no-store",
+        "expected_cache": "no-cache",
         "should_have_header": True,
     },
     {
-        "name": "index_json_no_store",
+        "name": "index_json_no_cache",
         "path": "/api/index.json",
         "status": 200,
-        "expected_cache": "no-store",
+        "expected_cache": "no-cache",
         "should_have_header": True,
     },
     {
-        "name": "localized_index_json_no_store",
+        "name": "localized_index_json_no_cache",
         "path": "/templates/index.zh.json",
         "status": 200,
-        "expected_cache": "no-store",
+        "expected_cache": "no-cache",
         "should_have_header": True,
     },
     # Non-matching files