refactor(assets): two-phase ingest — stub insert then hash

ingest_existing_file() now inserts a stub record (hash=NULL) first for
instant UX visibility, then computes the BLAKE3 hash and runs the full
ingest pipeline. No compute_hash flag exposed — both phases always run.

Amp-Thread-ID: https://ampcode.com/threads/T-019cc013-1444-73c8-81d6-07cae6e5e38d
Co-authored-by: Amp <amp@ampcode.com>

app/assets/services/ingest.py

@@ -23,6 +23,7 @@ from app.assets.database.queries import (
     validate_tags_exist,
 )
 from app.assets.helpers import normalize_tags
+from app.assets.services.bulk_ingest import batch_insert_seed_assets
 from app.assets.services.file_utils import get_size_and_mtime_ns
 from app.assets.services.path_utils import (
     compute_relative_filename,
@@ -138,19 +139,35 @@ def ingest_existing_file(
 ) -> IngestResult:
     """Register an existing on-disk file as an asset.
 
-    Handles stat, BLAKE3 hash, MIME detection, and path-based tag derivation.
-    Deduplicates by hash (same content → same Asset, new AssetReference).
+    Uses a two-phase approach: first inserts a stub record (hash=NULL) to
+    unblock UX immediately, then computes the BLAKE3 hash and updates the
+    asset with the full ingest pipeline (dedup, metadata, tags).
     """
     size_bytes, mtime_ns = get_size_and_mtime_ns(abs_path)
-
-    digest, _ = hashing.compute_blake3_hash(abs_path)
-    asset_hash = "blake3:" + digest
-
     mime_type = mimetypes.guess_type(abs_path, strict=False)[0]
-
     name, path_tags = get_name_and_tags_from_asset_path(abs_path)
     tags = list(dict.fromkeys(path_tags + list(extra_tags)))
 
+    # Phase 1: fast stub insert (hash=NULL) to make the asset visible immediately
+    spec = {
+        "abs_path": abs_path,
+        "size_bytes": size_bytes,
+        "mtime_ns": mtime_ns,
+        "info_name": name,
+        "tags": tags,
+        "fname": os.path.basename(abs_path),
+        "metadata": None,
+        "hash": None,
+        "mime_type": mime_type,
+    }
+    with create_session() as session:
+        batch_insert_seed_assets(session, [spec], owner_id=owner_id)
+        session.commit()
+
+    # Phase 2: compute hash and run full ingest (dedup, metadata, tags)
+    digest, _ = hashing.compute_blake3_hash(abs_path)
+    asset_hash = "blake3:" + digest
+
     return _ingest_file_from_path(
         abs_path=abs_path,
         asset_hash=asset_hash,