Clean up imports, remove section banners, and fix seed endpoint with autoscan disabled

Move inline/lazy imports to top-level now that blake3 is a main dependency and
circular-import concerns are resolved. Remove decorative section-header comments
in asset_reference queries. Allow the seed API endpoint to temporarily re-enable
the seeder when --disable-assets-autoscan is active so manual triggers still work.
Add retry-on-409 logic in test helpers and remove try/finally around prompt
execution in favour of sequential pause/resume.

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

app/assets/database/queries/asset.py

@@ -3,7 +3,7 @@ from sqlalchemy import select
 from sqlalchemy.dialects import sqlite
 from sqlalchemy.orm import Session
 
-from app.assets.database.models import Asset
+from app.assets.database.models import Asset, AssetReference
 from app.assets.database.queries.common import calculate_rows_per_statement, iter_chunks
 
 
@@ -130,8 +130,6 @@ def reassign_asset_references(
 
     Used when merging a stub asset into an existing asset with the same hash.
     """
-    from app.assets.database.models import AssetReference
-
     ref = session.get(AssetReference, reference_id)
     if ref:
         ref.asset_id = to_asset_id

app/assets/database/queries/asset_reference.py

@@ -32,11 +32,6 @@ from app.assets.database.queries.common import (
 from app.assets.helpers import escape_sql_like_string, get_utc_now, normalize_tags
 
 
-# =============================================================================
-# Metadata conversion helpers (from former asset_info.py)
-# =============================================================================
-
-
 def _check_is_scalar(v):
     if v is None:
         return True
@@ -84,11 +79,6 @@ def convert_metadata_to_rows(key: str, value) -> list[dict]:
     return [{"key": key, "ordinal": 0, "val_json": value}]
 
 
-# =============================================================================
-# Filter helpers
-# =============================================================================
-
-
 def _apply_tag_filters(
     stmt: sa.sql.Select,
     include_tags: Sequence[str] | None = None,
@@ -168,11 +158,6 @@ def _apply_metadata_filter(
     return stmt
 
 
-# =============================================================================
-# Basic CRUD operations
-# =============================================================================
-
-
 def get_reference_by_id(
     session: Session,
     reference_id: str,
@@ -302,11 +287,6 @@ def update_reference_timestamps(
     reference.updated_at = now
 
 
-# =============================================================================
-# Listing and pagination
-# =============================================================================
-
-
 def list_references_page(
     session: Session,
     owner_id: str = "",
@@ -440,11 +420,6 @@ def fetch_reference_and_asset(
     return pair[0], pair[1]
 
 
-# =============================================================================
-# Timestamp updates
-# =============================================================================
-
-
 def update_reference_access_time(
     session: Session,
     reference_id: str,
@@ -491,11 +466,6 @@ def update_reference_updated_at(
     )
 
 
-# =============================================================================
-# Metadata operations
-# =============================================================================
-
-
 def set_reference_metadata(
     session: Session,
     reference_id: str,
@@ -538,11 +508,6 @@ def set_reference_metadata(
         session.flush()
 
 
-# =============================================================================
-# Delete operations
-# =============================================================================
-
-
 def delete_reference_by_id(
     session: Session,
     reference_id: str,
@@ -576,11 +541,6 @@ def set_reference_preview(
     session.flush()
 
 
-# =============================================================================
-# Cache state operations (from former cache_state.py)
-# =============================================================================
-
-
 class CacheStateRow(NamedTuple):
     """Row from reference query with cache state data."""
 
@@ -867,11 +827,6 @@ def delete_orphaned_seed_asset(session: Session, asset_id: str) -> bool:
     return False
 
 
-# =============================================================================
-# Enrichment operations
-# =============================================================================
-
-
 class UnenrichedReferenceRow(NamedTuple):
     """Row for references needing enrichment."""
 
@@ -968,11 +923,6 @@ def bulk_update_enrichment_level(
     return result.rowcount
 
 
-# =============================================================================
-# Bulk operations
-# =============================================================================
-
-
 def bulk_insert_references_ignore_conflicts(
     session: Session,
     rows: list[dict],