diff --git a/tests-unit/assets_test/__init__.py b/tests-unit/assets_test/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests-unit/assets_test/conftest.py b/tests-unit/assets_test/conftest.py
new file mode 100644
index 000000000..2a25628c5
--- /dev/null
+++ b/tests-unit/assets_test/conftest.py
@@ -0,0 +1,104 @@
+"""
+Pytest fixtures for assets API tests.
+"""
+
+import io
+import pytest
+from unittest.mock import MagicMock, patch
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, Session
+
+from aiohttp import web
+
+pytestmark = pytest.mark.asyncio
+
+
+@pytest.fixture(scope="session")
+def in_memory_engine():
+    """Create an in-memory SQLite engine with all asset tables."""
+    engine = create_engine("sqlite:///:memory:", echo=False)
+    
+    from app.database.models import Base
+    from app.assets.database.models import (
+        Asset,
+        AssetInfo,
+        AssetCacheState,
+        AssetInfoMeta,
+        AssetInfoTag,
+        Tag,
+    )
+    
+    Base.metadata.create_all(engine)
+    
+    yield engine
+    
+    engine.dispose()
+
+
+@pytest.fixture
+def db_session(in_memory_engine) -> Session:
+    """Create a fresh database session for each test."""
+    SessionLocal = sessionmaker(bind=in_memory_engine)
+    session = SessionLocal()
+    
+    yield session
+    
+    session.rollback()
+    session.close()
+
+
+@pytest.fixture
+def mock_user_manager():
+    """Create a mock UserManager that returns a predictable owner_id."""
+    mock = MagicMock()
+    mock.get_request_user_id = MagicMock(return_value="test-user-123")
+    return mock
+
+
+@pytest.fixture
+def app(mock_user_manager) -> web.Application:
+    """Create an aiohttp Application with assets routes registered."""
+    from app.assets.api.routes import register_assets_system
+    
+    application = web.Application()
+    register_assets_system(application, mock_user_manager)
+    return application
+
+
+@pytest.fixture
+def test_image_bytes() -> bytes:
+    """Generate a minimal valid PNG image (10x10 red pixels)."""
+    from PIL import Image
+    
+    img = Image.new("RGB", (10, 10), color="red")
+    buffer = io.BytesIO()
+    img.save(buffer, format="PNG")
+    return buffer.getvalue()
+
+
+@pytest.fixture
+def tmp_upload_dir(tmp_path):
+    """Create a temporary directory for uploads and patch folder_paths."""
+    upload_dir = tmp_path / "uploads"
+    upload_dir.mkdir()
+    
+    with patch("folder_paths.get_temp_directory", return_value=str(tmp_path)):
+        yield tmp_path
+
+
+@pytest.fixture(autouse=True)
+def patch_create_session(in_memory_engine):
+    """Patch create_session to use our in-memory database."""
+    SessionLocal = sessionmaker(bind=in_memory_engine)
+    
+    with patch("app.database.db.Session", SessionLocal):
+        with patch("app.database.db.create_session", lambda: SessionLocal()):
+            with patch("app.database.db.can_create_session", return_value=True):
+                yield
+
+
+async def test_fixtures_work(db_session, mock_user_manager):
+    """Smoke test to verify fixtures are working."""
+    assert db_session is not None
+    assert mock_user_manager.get_request_user_id(None) == "test-user-123"
diff --git a/tests-unit/assets_test/helpers_test.py b/tests-unit/assets_test/helpers_test.py
new file mode 100644
index 000000000..ea5e08084
--- /dev/null
+++ b/tests-unit/assets_test/helpers_test.py
@@ -0,0 +1,317 @@
+"""Tests for app.assets.helpers utility functions."""
+
+import os
+import pytest
+from datetime import datetime, timezone
+from decimal import Decimal
+from unittest.mock import MagicMock
+
+from app.assets.helpers import (
+    normalize_tags,
+    escape_like_prefix,
+    ensure_within_base,
+    get_query_dict,
+    utcnow,
+    project_kv,
+    is_scalar,
+    fast_asset_file_check,
+    list_tree,
+    RootType,
+    ALLOWED_ROOTS,
+)
+
+
+class TestNormalizeTags:
+    def test_lowercases(self):
+        assert normalize_tags(["FOO", "Bar"]) == ["foo", "bar"]
+
+    def test_strips_whitespace(self):
+        assert normalize_tags(["  hello  ", "world "]) == ["hello", "world"]
+
+    def test_does_not_deduplicate(self):
+        result = normalize_tags(["a", "A", "a"])
+        assert result == ["a", "a", "a"]
+
+    def test_none_returns_empty(self):
+        assert normalize_tags(None) == []
+
+    def test_empty_list_returns_empty(self):
+        assert normalize_tags([]) == []
+
+    def test_filters_empty_strings(self):
+        assert normalize_tags(["a", "", "  ", "b"]) == ["a", "b"]
+
+    def test_preserves_order(self):
+        result = normalize_tags(["Z", "A", "z", "B"])
+        assert result == ["z", "a", "z", "b"]
+
+
+class TestEscapeLikePrefix:
+    def test_escapes_percent(self):
+        result, esc = escape_like_prefix("50%")
+        assert result == "50!%"
+        assert esc == "!"
+
+    def test_escapes_underscore(self):
+        result, esc = escape_like_prefix("file_name")
+        assert result == "file!_name"
+        assert esc == "!"
+
+    def test_escapes_escape_char(self):
+        result, esc = escape_like_prefix("a!b")
+        assert result == "a!!b"
+        assert esc == "!"
+
+    def test_normal_string_unchanged(self):
+        result, esc = escape_like_prefix("hello")
+        assert result == "hello"
+        assert esc == "!"
+
+    def test_complex_string(self):
+        result, esc = escape_like_prefix("50%_!x")
+        assert result == "50!%!_!!x"
+
+    def test_custom_escape_char(self):
+        result, esc = escape_like_prefix("50%", escape="\\")
+        assert result == "50\\%"
+        assert esc == "\\"
+
+
+class TestEnsureWithinBase:
+    def test_valid_path_within_base(self, tmp_path):
+        base = str(tmp_path)
+        candidate = str(tmp_path / "subdir" / "file.txt")
+        ensure_within_base(candidate, base)
+
+    def test_path_traversal_rejected(self, tmp_path):
+        base = str(tmp_path / "safe")
+        candidate = str(tmp_path / "safe" / ".." / "unsafe")
+        with pytest.raises(ValueError, match="escapes base directory|invalid destination"):
+            ensure_within_base(candidate, base)
+
+    def test_completely_outside_path_rejected(self, tmp_path):
+        base = str(tmp_path / "safe")
+        candidate = "/etc/passwd"
+        with pytest.raises(ValueError):
+            ensure_within_base(candidate, base)
+
+    def test_same_path_is_valid(self, tmp_path):
+        base = str(tmp_path)
+        ensure_within_base(base, base)
+
+
+class TestGetQueryDict:
+    def test_single_values(self):
+        request = MagicMock()
+        request.query.keys.return_value = ["a", "b"]
+        request.query.get.side_effect = lambda k: {"a": "1", "b": "2"}[k]
+        request.query.getall.side_effect = lambda k: [{"a": "1", "b": "2"}[k]]
+
+        result = get_query_dict(request)
+        assert result == {"a": "1", "b": "2"}
+
+    def test_multiple_values_same_key(self):
+        request = MagicMock()
+        request.query.keys.return_value = ["tags"]
+        request.query.get.return_value = "tag1"
+        request.query.getall.return_value = ["tag1", "tag2", "tag3"]
+
+        result = get_query_dict(request)
+        assert result == {"tags": ["tag1", "tag2", "tag3"]}
+
+    def test_empty_query(self):
+        request = MagicMock()
+        request.query.keys.return_value = []
+
+        result = get_query_dict(request)
+        assert result == {}
+
+
+class TestUtcnow:
+    def test_returns_datetime(self):
+        result = utcnow()
+        assert isinstance(result, datetime)
+
+    def test_no_tzinfo(self):
+        result = utcnow()
+        assert result.tzinfo is None
+
+    def test_is_approximately_now(self):
+        before = datetime.now(timezone.utc).replace(tzinfo=None)
+        result = utcnow()
+        after = datetime.now(timezone.utc).replace(tzinfo=None)
+        assert before <= result <= after
+
+
+class TestIsScalar:
+    def test_none_is_scalar(self):
+        assert is_scalar(None) is True
+
+    def test_bool_is_scalar(self):
+        assert is_scalar(True) is True
+        assert is_scalar(False) is True
+
+    def test_int_is_scalar(self):
+        assert is_scalar(42) is True
+
+    def test_float_is_scalar(self):
+        assert is_scalar(3.14) is True
+
+    def test_decimal_is_scalar(self):
+        assert is_scalar(Decimal("10.5")) is True
+
+    def test_str_is_scalar(self):
+        assert is_scalar("hello") is True
+
+    def test_list_is_not_scalar(self):
+        assert is_scalar([1, 2, 3]) is False
+
+    def test_dict_is_not_scalar(self):
+        assert is_scalar({"a": 1}) is False
+
+
+class TestProjectKv:
+    def test_none_value(self):
+        result = project_kv("key", None)
+        assert len(result) == 1
+        assert result[0]["key"] == "key"
+        assert result[0]["ordinal"] == 0
+        assert result[0]["val_str"] is None
+        assert result[0]["val_num"] is None
+
+    def test_string_value(self):
+        result = project_kv("name", "test")
+        assert len(result) == 1
+        assert result[0]["val_str"] == "test"
+
+    def test_int_value(self):
+        result = project_kv("count", 42)
+        assert len(result) == 1
+        assert result[0]["val_num"] == Decimal("42")
+
+    def test_float_value(self):
+        result = project_kv("ratio", 3.14)
+        assert len(result) == 1
+        assert result[0]["val_num"] == Decimal("3.14")
+
+    def test_bool_value(self):
+        result = project_kv("enabled", True)
+        assert len(result) == 1
+        assert result[0]["val_bool"] is True
+
+    def test_list_of_strings(self):
+        result = project_kv("tags", ["a", "b", "c"])
+        assert len(result) == 3
+        assert result[0]["ordinal"] == 0
+        assert result[0]["val_str"] == "a"
+        assert result[1]["ordinal"] == 1
+        assert result[1]["val_str"] == "b"
+        assert result[2]["ordinal"] == 2
+        assert result[2]["val_str"] == "c"
+
+    def test_list_of_mixed_scalars(self):
+        result = project_kv("mixed", [1, "two", True])
+        assert len(result) == 3
+        assert result[0]["val_num"] == Decimal("1")
+        assert result[1]["val_str"] == "two"
+        assert result[2]["val_bool"] is True
+
+    def test_list_with_none(self):
+        result = project_kv("items", ["a", None, "b"])
+        assert len(result) == 3
+        assert result[1]["val_str"] is None
+        assert result[1]["val_num"] is None
+
+    def test_dict_value_stored_as_json(self):
+        result = project_kv("meta", {"nested": "value"})
+        assert len(result) == 1
+        assert result[0]["val_json"] == {"nested": "value"}
+
+    def test_list_of_dicts_stored_as_json(self):
+        result = project_kv("items", [{"a": 1}, {"b": 2}])
+        assert len(result) == 2
+        assert result[0]["val_json"] == {"a": 1}
+        assert result[1]["val_json"] == {"b": 2}
+
+
+class TestFastAssetFileCheck:
+    def test_none_mtime_returns_false(self):
+        stat = MagicMock()
+        assert fast_asset_file_check(mtime_db=None, size_db=100, stat_result=stat) is False
+
+    def test_matching_mtime_and_size(self):
+        stat = MagicMock()
+        stat.st_mtime_ns = 1234567890123456789
+        stat.st_size = 100
+
+        result = fast_asset_file_check(
+            mtime_db=1234567890123456789,
+            size_db=100,
+            stat_result=stat
+        )
+        assert result is True
+
+    def test_mismatched_mtime(self):
+        stat = MagicMock()
+        stat.st_mtime_ns = 9999999999999999999
+        stat.st_size = 100
+
+        result = fast_asset_file_check(
+            mtime_db=1234567890123456789,
+            size_db=100,
+            stat_result=stat
+        )
+        assert result is False
+
+    def test_mismatched_size(self):
+        stat = MagicMock()
+        stat.st_mtime_ns = 1234567890123456789
+        stat.st_size = 200
+
+        result = fast_asset_file_check(
+            mtime_db=1234567890123456789,
+            size_db=100,
+            stat_result=stat
+        )
+        assert result is False
+
+    def test_zero_size_skips_size_check(self):
+        stat = MagicMock()
+        stat.st_mtime_ns = 1234567890123456789
+        stat.st_size = 999
+
+        result = fast_asset_file_check(
+            mtime_db=1234567890123456789,
+            size_db=0,
+            stat_result=stat
+        )
+        assert result is True
+
+
+class TestListTree:
+    def test_lists_files_in_directory(self, tmp_path):
+        (tmp_path / "file1.txt").touch()
+        (tmp_path / "file2.txt").touch()
+        subdir = tmp_path / "subdir"
+        subdir.mkdir()
+        (subdir / "file3.txt").touch()
+
+        result = list_tree(str(tmp_path))
+        assert len(result) == 3
+        assert all(os.path.isabs(p) for p in result)
+        assert str(tmp_path / "file1.txt") in result
+        assert str(tmp_path / "subdir" / "file3.txt") in result
+
+    def test_nonexistent_directory_returns_empty(self):
+        result = list_tree("/nonexistent/path/that/does/not/exist")
+        assert result == []
+
+
+class TestRootType:
+    def test_allowed_roots_contains_expected_values(self):
+        assert "models" in ALLOWED_ROOTS
+        assert "input" in ALLOWED_ROOTS
+        assert "output" in ALLOWED_ROOTS
+
+    def test_allowed_roots_is_tuple(self):
+        assert isinstance(ALLOWED_ROOTS, tuple)
diff --git a/tests-unit/assets_test/queries_crud_test.py b/tests-unit/assets_test/queries_crud_test.py
new file mode 100644
index 000000000..70257c1be
--- /dev/null
+++ b/tests-unit/assets_test/queries_crud_test.py
@@ -0,0 +1,597 @@
+"""
+Tests for core CRUD database query functions in app.assets.database.queries.
+"""
+
+import pytest
+import uuid
+from datetime import datetime, timedelta, timezone
+
+from app.assets.database.queries import (
+    asset_exists_by_hash,
+    get_asset_by_hash,
+    get_asset_info_by_id,
+    create_asset_info_for_existing_asset,
+    ingest_fs_asset,
+    delete_asset_info_by_id,
+    touch_asset_info_by_id,
+    update_asset_info_full,
+    fetch_asset_info_and_asset,
+    fetch_asset_info_asset_and_tags,
+    ensure_tags_exist,
+)
+from app.assets.database.models import Asset, AssetInfo, AssetCacheState
+
+
+def make_hash(seed: str = "a") -> str:
+    return "blake3:" + seed * 64
+
+
+def make_unique_hash() -> str:
+    return "blake3:" + uuid.uuid4().hex + uuid.uuid4().hex
+
+
+class TestAssetExistsByHash:
+    def test_returns_true_when_exists(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"fake png data")
+        asset_hash = make_unique_hash()
+
+        ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=len(b"fake png data"),
+            mtime_ns=1000000,
+            mime_type="image/png",
+        )
+        db_session.flush()
+
+        assert asset_exists_by_hash(db_session, asset_hash=asset_hash) is True
+
+    def test_returns_false_when_missing(self, db_session):
+        assert asset_exists_by_hash(db_session, asset_hash=make_unique_hash()) is False
+
+
+class TestGetAssetByHash:
+    def test_returns_asset_when_exists(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"test data")
+        asset_hash = make_unique_hash()
+
+        ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=9,
+            mtime_ns=1000000,
+            mime_type="image/png",
+        )
+        db_session.flush()
+
+        asset = get_asset_by_hash(db_session, asset_hash=asset_hash)
+        assert asset is not None
+        assert asset.hash == asset_hash
+        assert asset.size_bytes == 9
+        assert asset.mime_type == "image/png"
+
+    def test_returns_none_when_missing(self, db_session):
+        result = get_asset_by_hash(db_session, asset_hash=make_unique_hash())
+        assert result is None
+
+
+class TestGetAssetInfoById:
+    def test_returns_asset_info_when_exists(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"test data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=9,
+            mtime_ns=1000000,
+            info_name="my-asset",
+            owner_id="user1",
+        )
+        db_session.flush()
+
+        info = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        assert info is not None
+        assert info.name == "my-asset"
+        assert info.owner_id == "user1"
+
+    def test_returns_none_when_missing(self, db_session):
+        fake_id = str(uuid.uuid4())
+        result = get_asset_info_by_id(db_session, asset_info_id=fake_id)
+        assert result is None
+
+
+class TestCreateAssetInfoForExistingAsset:
+    def test_creates_linked_asset_info(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"test data")
+        asset_hash = make_unique_hash()
+
+        ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=9,
+            mtime_ns=1000000,
+        )
+        db_session.flush()
+
+        info = create_asset_info_for_existing_asset(
+            db_session,
+            asset_hash=asset_hash,
+            name="new-info",
+            owner_id="owner123",
+            user_metadata={"key": "value"},
+        )
+        db_session.flush()
+
+        assert info is not None
+        assert info.name == "new-info"
+        assert info.owner_id == "owner123"
+
+        asset = get_asset_by_hash(db_session, asset_hash=asset_hash)
+        assert info.asset_id == asset.id
+
+    def test_raises_on_unknown_hash(self, db_session):
+        with pytest.raises(ValueError, match="Unknown asset hash"):
+            create_asset_info_for_existing_asset(
+                db_session,
+                asset_hash=make_unique_hash(),
+                name="test",
+            )
+
+    def test_returns_existing_on_duplicate(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"test data")
+        asset_hash = make_unique_hash()
+
+        ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=9,
+            mtime_ns=1000000,
+        )
+        db_session.flush()
+
+        info1 = create_asset_info_for_existing_asset(
+            db_session,
+            asset_hash=asset_hash,
+            name="same-name",
+            owner_id="owner1",
+        )
+        db_session.flush()
+
+        info2 = create_asset_info_for_existing_asset(
+            db_session,
+            asset_hash=asset_hash,
+            name="same-name",
+            owner_id="owner1",
+        )
+        db_session.flush()
+
+        assert info1.id == info2.id
+
+
+class TestIngestFsAsset:
+    def test_creates_all_records(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"fake png data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=len(b"fake png data"),
+            mtime_ns=1000000,
+            mime_type="image/png",
+            info_name="test-asset",
+            owner_id="user1",
+        )
+        db_session.flush()
+
+        assert result["asset_created"] is True
+        assert result["state_created"] is True
+        assert result["asset_info_id"] is not None
+
+        asset = get_asset_by_hash(db_session, asset_hash=asset_hash)
+        assert asset is not None
+        assert asset.size_bytes == len(b"fake png data")
+
+        info = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        assert info is not None
+        assert info.name == "test-asset"
+
+        cache_states = db_session.query(AssetCacheState).filter_by(asset_id=asset.id).all()
+        assert len(cache_states) == 1
+        assert cache_states[0].file_path == str(test_file)
+
+    def test_idempotent_on_same_file(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result1 = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        result2 = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        assert result1["asset_info_id"] == result2["asset_info_id"]
+        assert result2["asset_created"] is False
+
+    def test_creates_with_tags(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+            tags=["tag1", "tag2"],
+        )
+        db_session.flush()
+
+        info, asset, tags = fetch_asset_info_asset_and_tags(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+        )
+        assert set(tags) == {"tag1", "tag2"}
+
+
+class TestDeleteAssetInfoById:
+    def test_deletes_existing_record(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="to-delete",
+            owner_id="user1",
+        )
+        db_session.flush()
+
+        deleted = delete_asset_info_by_id(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            owner_id="user1",
+        )
+        db_session.flush()
+
+        assert deleted is True
+        assert get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"]) is None
+
+    def test_returns_false_for_nonexistent(self, db_session):
+        result = delete_asset_info_by_id(
+            db_session,
+            asset_info_id=str(uuid.uuid4()),
+            owner_id="user1",
+        )
+        assert result is False
+
+    def test_respects_owner_visibility(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="owned-asset",
+            owner_id="user1",
+        )
+        db_session.flush()
+
+        deleted = delete_asset_info_by_id(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            owner_id="different-user",
+        )
+        assert deleted is False
+
+        assert get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"]) is not None
+
+
+class TestTouchAssetInfoById:
+    def test_updates_last_access_time(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        info_before = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        original_time = info_before.last_access_time
+
+        new_time = datetime.now(timezone.utc).replace(tzinfo=None) + timedelta(hours=1)
+        touch_asset_info_by_id(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            ts=new_time,
+        )
+        db_session.flush()
+        db_session.expire_all()
+
+        info_after = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        assert info_after.last_access_time == new_time
+        assert info_after.last_access_time > original_time
+
+    def test_only_if_newer_respects_flag(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        info = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        original_time = info.last_access_time
+
+        older_time = original_time - timedelta(hours=1)
+        touch_asset_info_by_id(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            ts=older_time,
+            only_if_newer=True,
+        )
+        db_session.flush()
+        db_session.expire_all()
+
+        info_after = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        assert info_after.last_access_time == original_time
+
+
+class TestUpdateAssetInfoFull:
+    def test_updates_name(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="original-name",
+        )
+        db_session.flush()
+
+        updated = update_asset_info_full(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            name="new-name",
+        )
+        db_session.flush()
+
+        assert updated.name == "new-name"
+
+    def test_updates_tags(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        update_asset_info_full(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["newtag1", "newtag2"],
+        )
+        db_session.flush()
+
+        _, _, tags = fetch_asset_info_asset_and_tags(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+        )
+        assert set(tags) == {"newtag1", "newtag2"}
+
+    def test_updates_metadata(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        update_asset_info_full(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            user_metadata={"custom_key": "custom_value"},
+        )
+        db_session.flush()
+        db_session.expire_all()
+
+        info = get_asset_info_by_id(db_session, asset_info_id=result["asset_info_id"])
+        assert "custom_key" in info.user_metadata
+        assert info.user_metadata["custom_key"] == "custom_value"
+
+    def test_raises_on_invalid_id(self, db_session):
+        with pytest.raises(ValueError, match="not found"):
+            update_asset_info_full(
+                db_session,
+                asset_info_id=str(uuid.uuid4()),
+                name="test",
+            )
+
+
+class TestFetchAssetInfoAndAsset:
+    def test_returns_tuple_when_exists(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+            mime_type="image/png",
+        )
+        db_session.flush()
+
+        fetched = fetch_asset_info_and_asset(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+        )
+
+        assert fetched is not None
+        info, asset = fetched
+        assert info.name == "test"
+        assert asset.hash == asset_hash
+        assert asset.mime_type == "image/png"
+
+    def test_returns_none_when_missing(self, db_session):
+        result = fetch_asset_info_and_asset(
+            db_session,
+            asset_info_id=str(uuid.uuid4()),
+        )
+        assert result is None
+
+    def test_respects_owner_visibility(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+            owner_id="user1",
+        )
+        db_session.flush()
+
+        fetched = fetch_asset_info_and_asset(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            owner_id="different-user",
+        )
+        assert fetched is None
+
+
+class TestFetchAssetInfoAssetAndTags:
+    def test_returns_tuple_with_tags(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+            tags=["alpha", "beta"],
+        )
+        db_session.flush()
+
+        fetched = fetch_asset_info_asset_and_tags(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+        )
+
+        assert fetched is not None
+        info, asset, tags = fetched
+        assert info.name == "test"
+        assert asset.hash == asset_hash
+        assert set(tags) == {"alpha", "beta"}
+
+    def test_returns_empty_tags_when_none(self, db_session, tmp_path):
+        test_file = tmp_path / "test.png"
+        test_file.write_bytes(b"data")
+        asset_hash = make_unique_hash()
+
+        result = ingest_fs_asset(
+            db_session,
+            asset_hash=asset_hash,
+            abs_path=str(test_file),
+            size_bytes=4,
+            mtime_ns=1000000,
+            info_name="test",
+        )
+        db_session.flush()
+
+        fetched = fetch_asset_info_asset_and_tags(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+        )
+
+        assert fetched is not None
+        info, asset, tags = fetched
+        assert tags == []
+
+    def test_returns_none_when_missing(self, db_session):
+        result = fetch_asset_info_asset_and_tags(
+            db_session,
+            asset_info_id=str(uuid.uuid4()),
+        )
+        assert result is None
diff --git a/tests-unit/assets_test/queries_filter_test.py b/tests-unit/assets_test/queries_filter_test.py
new file mode 100644
index 000000000..82d7ec674
--- /dev/null
+++ b/tests-unit/assets_test/queries_filter_test.py
@@ -0,0 +1,471 @@
+"""
+Tests for filtering and pagination query functions in app.assets.database.queries.
+"""
+
+import hashlib
+import uuid
+from pathlib import Path
+
+import pytest
+from sqlalchemy import create_engine, delete
+from sqlalchemy.orm import Session, sessionmaker
+
+from app.assets.database.models import Asset, AssetInfo, AssetInfoTag, AssetInfoMeta, AssetCacheState, Tag
+from app.assets.database.queries import (
+    apply_metadata_filter,
+    apply_tag_filters,
+    ingest_fs_asset,
+    list_asset_infos_page,
+    replace_asset_info_metadata_projection,
+    visible_owner_clause,
+)
+from app.assets.helpers import utcnow
+from sqlalchemy import select
+from app.database.models import Base
+
+
+@pytest.fixture
+def clean_db_session():
+    """Create a fresh in-memory database for each test."""
+    engine = create_engine("sqlite:///:memory:", echo=False)
+    Base.metadata.create_all(engine)
+    SessionLocal = sessionmaker(bind=engine)
+    session = SessionLocal()
+    yield session
+    session.rollback()
+    session.close()
+    engine.dispose()
+
+
+def seed_assets(
+    session: Session,
+    tmp_path: Path,
+    count: int = 10,
+    owner_id: str = "",
+    tag_sets: list[list[str]] | None = None,
+) -> list[str]:
+    """
+    Create test assets with varied tags.
+    Returns list of asset_info_ids.
+    """
+    asset_info_ids = []
+    for i in range(count):
+        f = tmp_path / f"test_{i}.png"
+        f.write_bytes(b"x" * (100 + i))
+        asset_hash = hashlib.sha256(f"unique-{uuid.uuid4()}".encode()).hexdigest()
+
+        if tag_sets is not None:
+            tags = tag_sets[i % len(tag_sets)]
+        else:
+            tags = ["input"] if i % 2 == 0 else ["models", "loras"]
+
+        result = ingest_fs_asset(
+            session,
+            asset_hash=asset_hash,
+            abs_path=str(f),
+            size_bytes=100 + i,
+            mtime_ns=1000000000 + i,
+            mime_type="image/png",
+            info_name=f"test_asset_{i}.png",
+            owner_id=owner_id,
+            tags=tags,
+        )
+        if result.get("asset_info_id"):
+            asset_info_ids.append(result["asset_info_id"])
+
+    session.commit()
+    return asset_info_ids
+
+
+class TestListAssetInfosPage:
+    @pytest.fixture
+    def seeded_db(self, clean_db_session, tmp_path):
+        seed_assets(clean_db_session, tmp_path, 15, owner_id="")
+        return clean_db_session
+
+    def test_pagination_limit(self, seeded_db):
+        infos, _, total = list_asset_infos_page(
+            seeded_db, owner_id="", limit=5, offset=0
+        )
+        assert len(infos) <= 5
+        assert total >= 5
+
+    def test_pagination_offset(self, seeded_db):
+        first_page, _, total = list_asset_infos_page(
+            seeded_db, owner_id="", limit=5, offset=0
+        )
+        second_page, _, _ = list_asset_infos_page(
+            seeded_db, owner_id="", limit=5, offset=5
+        )
+
+        first_ids = {i.id for i in first_page}
+        second_ids = {i.id for i in second_page}
+        assert first_ids.isdisjoint(second_ids)
+
+    def test_returns_tuple_with_tag_map(self, seeded_db):
+        infos, tag_map, total = list_asset_infos_page(
+            seeded_db, owner_id="", limit=10, offset=0
+        )
+        assert isinstance(infos, list)
+        assert isinstance(tag_map, dict)
+        assert isinstance(total, int)
+
+        for info in infos:
+            if info.id in tag_map:
+                assert isinstance(tag_map[info.id], list)
+
+    def test_total_count_matches(self, seeded_db):
+        _, _, total = list_asset_infos_page(seeded_db, owner_id="", limit=100, offset=0)
+        assert total == 15
+
+
+class TestApplyTagFilters:
+    @pytest.fixture
+    def tagged_db(self, clean_db_session, tmp_path):
+        tag_sets = [
+            ["alpha", "beta"],
+            ["alpha", "gamma"],
+            ["beta", "gamma"],
+            ["alpha", "beta", "gamma"],
+            ["delta"],
+        ]
+        seed_assets(clean_db_session, tmp_path, 5, owner_id="", tag_sets=tag_sets)
+        return clean_db_session
+
+    def test_include_tags_requires_all(self, tagged_db):
+        infos, tag_map, _ = list_asset_infos_page(
+            tagged_db,
+            owner_id="",
+            include_tags=["alpha", "beta"],
+            limit=100,
+        )
+        for info in infos:
+            tags = tag_map.get(info.id, [])
+            assert "alpha" in tags and "beta" in tags
+
+    def test_include_single_tag(self, tagged_db):
+        infos, tag_map, total = list_asset_infos_page(
+            tagged_db,
+            owner_id="",
+            include_tags=["alpha"],
+            limit=100,
+        )
+        assert total >= 1
+        for info in infos:
+            tags = tag_map.get(info.id, [])
+            assert "alpha" in tags
+
+    def test_exclude_tags_excludes_any(self, tagged_db):
+        infos, tag_map, _ = list_asset_infos_page(
+            tagged_db,
+            owner_id="",
+            exclude_tags=["delta"],
+            limit=100,
+        )
+        for info in infos:
+            tags = tag_map.get(info.id, [])
+            assert "delta" not in tags
+
+    def test_exclude_multiple_tags(self, tagged_db):
+        infos, tag_map, _ = list_asset_infos_page(
+            tagged_db,
+            owner_id="",
+            exclude_tags=["alpha", "delta"],
+            limit=100,
+        )
+        for info in infos:
+            tags = tag_map.get(info.id, [])
+            assert "alpha" not in tags
+            assert "delta" not in tags
+
+    def test_combine_include_and_exclude(self, tagged_db):
+        infos, tag_map, _ = list_asset_infos_page(
+            tagged_db,
+            owner_id="",
+            include_tags=["alpha"],
+            exclude_tags=["gamma"],
+            limit=100,
+        )
+        for info in infos:
+            tags = tag_map.get(info.id, [])
+            assert "alpha" in tags
+            assert "gamma" not in tags
+
+
+class TestApplyMetadataFilter:
+    @pytest.fixture
+    def metadata_db(self, clean_db_session, tmp_path):
+        ids = seed_assets(clean_db_session, tmp_path, 5, owner_id="")
+        metadata_sets = [
+            {"author": "alice", "version": 1},
+            {"author": "bob", "version": 2},
+            {"author": "alice", "version": 2},
+            {"author": "charlie", "active": True},
+            {"author": "alice", "active": False},
+        ]
+        for i, info_id in enumerate(ids):
+            replace_asset_info_metadata_projection(
+                clean_db_session,
+                asset_info_id=info_id,
+                user_metadata=metadata_sets[i],
+            )
+        clean_db_session.commit()
+        return clean_db_session
+
+    def test_filter_by_string_value(self, metadata_db):
+        infos, _, total = list_asset_infos_page(
+            metadata_db,
+            owner_id="",
+            metadata_filter={"author": "alice"},
+            limit=100,
+        )
+        assert total == 3
+        for info in infos:
+            assert info.user_metadata.get("author") == "alice"
+
+    def test_filter_by_numeric_value(self, metadata_db):
+        infos, _, total = list_asset_infos_page(
+            metadata_db,
+            owner_id="",
+            metadata_filter={"version": 2},
+            limit=100,
+        )
+        assert total == 2
+
+    def test_filter_by_boolean_value(self, metadata_db):
+        infos, _, total = list_asset_infos_page(
+            metadata_db,
+            owner_id="",
+            metadata_filter={"active": True},
+            limit=100,
+        )
+        assert total == 1
+
+    def test_filter_by_multiple_keys(self, metadata_db):
+        infos, _, total = list_asset_infos_page(
+            metadata_db,
+            owner_id="",
+            metadata_filter={"author": "alice", "version": 2},
+            limit=100,
+        )
+        assert total == 1
+
+    def test_filter_with_list_values(self, metadata_db):
+        infos, _, total = list_asset_infos_page(
+            metadata_db,
+            owner_id="",
+            metadata_filter={"author": ["alice", "bob"]},
+            limit=100,
+        )
+        assert total == 4
+
+
+class TestVisibleOwnerClause:
+    @pytest.fixture
+    def multi_owner_db(self, clean_db_session, tmp_path):
+        seed_assets(clean_db_session, tmp_path, 3, owner_id="user1")
+        seed_assets(clean_db_session, tmp_path, 2, owner_id="user2")
+        seed_assets(clean_db_session, tmp_path, 4, owner_id="")
+        return clean_db_session
+
+    def test_empty_owner_sees_only_public(self, multi_owner_db):
+        infos, _, total = list_asset_infos_page(
+            multi_owner_db,
+            owner_id="",
+            limit=100,
+        )
+        assert total == 4
+        for info in infos:
+            assert info.owner_id == ""
+
+    def test_owner_sees_own_plus_public(self, multi_owner_db):
+        infos, _, total = list_asset_infos_page(
+            multi_owner_db,
+            owner_id="user1",
+            limit=100,
+        )
+        assert total == 7
+        owner_ids = {info.owner_id for info in infos}
+        assert owner_ids == {"user1", ""}
+
+    def test_owner_sees_only_own_and_public(self, multi_owner_db):
+        infos, _, total = list_asset_infos_page(
+            multi_owner_db,
+            owner_id="user2",
+            limit=100,
+        )
+        assert total == 6
+        owner_ids = {info.owner_id for info in infos}
+        assert owner_ids == {"user2", ""}
+        assert all(info.owner_id in ("user2", "") for info in infos)
+
+    def test_nonexistent_owner_sees_public(self, multi_owner_db):
+        infos, _, total = list_asset_infos_page(
+            multi_owner_db,
+            owner_id="unknown-user",
+            limit=100,
+        )
+        assert total == 4
+        for info in infos:
+            assert info.owner_id == ""
+
+
+class TestSorting:
+    @pytest.fixture
+    def sortable_db(self, clean_db_session, tmp_path):
+        import time
+
+        ids = []
+        names = ["zebra.png", "alpha.png", "mango.png"]
+        sizes = [500, 100, 300]
+
+        for i, name in enumerate(names):
+            f = tmp_path / f"sort_{i}.png"
+            f.write_bytes(b"x" * sizes[i])
+            asset_hash = hashlib.sha256(f"sort-{uuid.uuid4()}".encode()).hexdigest()
+
+            result = ingest_fs_asset(
+                clean_db_session,
+                asset_hash=asset_hash,
+                abs_path=str(f),
+                size_bytes=sizes[i],
+                mtime_ns=1000000000 + i,
+                mime_type="image/png",
+                info_name=name,
+                owner_id="",
+                tags=["test"],
+            )
+            ids.append(result["asset_info_id"])
+            time.sleep(0.01)
+
+        clean_db_session.commit()
+        return clean_db_session
+
+    def test_sort_by_name_asc(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="name",
+            order="asc",
+            limit=100,
+        )
+        names = [i.name for i in infos]
+        assert names == sorted(names)
+
+    def test_sort_by_name_desc(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="name",
+            order="desc",
+            limit=100,
+        )
+        names = [i.name for i in infos]
+        assert names == sorted(names, reverse=True)
+
+    def test_sort_by_size(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="size",
+            order="asc",
+            limit=100,
+        )
+        sizes = [i.asset.size_bytes for i in infos]
+        assert sizes == sorted(sizes)
+
+    def test_sort_by_created_at_desc(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="created_at",
+            order="desc",
+            limit=100,
+        )
+        dates = [i.created_at for i in infos]
+        assert dates == sorted(dates, reverse=True)
+
+    def test_sort_by_updated_at(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="updated_at",
+            order="desc",
+            limit=100,
+        )
+        dates = [i.updated_at for i in infos]
+        assert dates == sorted(dates, reverse=True)
+
+    def test_sort_by_last_access_time(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="last_access_time",
+            order="asc",
+            limit=100,
+        )
+        times = [i.last_access_time for i in infos]
+        assert times == sorted(times)
+
+    def test_invalid_sort_defaults_to_created_at(self, sortable_db):
+        infos, _, _ = list_asset_infos_page(
+            sortable_db,
+            owner_id="",
+            sort="invalid_column",
+            order="desc",
+            limit=100,
+        )
+        dates = [i.created_at for i in infos]
+        assert dates == sorted(dates, reverse=True)
+
+
+class TestNameContainsFilter:
+    @pytest.fixture
+    def named_db(self, clean_db_session, tmp_path):
+        names = ["report_2023.pdf", "report_2024.pdf", "image.png", "data.csv"]
+        for i, name in enumerate(names):
+            f = tmp_path / f"file_{i}.bin"
+            f.write_bytes(b"x" * 100)
+            asset_hash = hashlib.sha256(f"named-{uuid.uuid4()}".encode()).hexdigest()
+            ingest_fs_asset(
+                clean_db_session,
+                asset_hash=asset_hash,
+                abs_path=str(f),
+                size_bytes=100,
+                mtime_ns=1000000000,
+                mime_type="application/octet-stream",
+                info_name=name,
+                owner_id="",
+                tags=["test"],
+            )
+        clean_db_session.commit()
+        return clean_db_session
+
+    def test_name_contains_filter(self, named_db):
+        infos, _, total = list_asset_infos_page(
+            named_db,
+            owner_id="",
+            name_contains="report",
+            limit=100,
+        )
+        assert total == 2
+        for info in infos:
+            assert "report" in info.name.lower()
+
+    def test_name_contains_case_insensitive(self, named_db):
+        infos, _, total = list_asset_infos_page(
+            named_db,
+            owner_id="",
+            name_contains="REPORT",
+            limit=100,
+        )
+        assert total == 2
+
+    def test_name_contains_partial_match(self, named_db):
+        infos, _, total = list_asset_infos_page(
+            named_db,
+            owner_id="",
+            name_contains=".p",
+            limit=100,
+        )
+        assert total >= 1
diff --git a/tests-unit/assets_test/queries_tags_test.py b/tests-unit/assets_test/queries_tags_test.py
new file mode 100644
index 000000000..962d4bad4
--- /dev/null
+++ b/tests-unit/assets_test/queries_tags_test.py
@@ -0,0 +1,380 @@
+"""
+Tests for tag-related database query functions in app.assets.database.queries.
+"""
+
+import pytest
+import uuid
+
+from app.assets.database.queries import (
+    add_tags_to_asset_info,
+    remove_tags_from_asset_info,
+    get_asset_tags,
+    list_tags_with_usage,
+    set_asset_info_preview,
+    ingest_fs_asset,
+    get_asset_by_hash,
+)
+
+
+def make_unique_hash() -> str:
+    return "blake3:" + uuid.uuid4().hex + uuid.uuid4().hex
+
+
+def create_test_asset(db_session, tmp_path, name="test", tags=None, owner_id=""):
+    test_file = tmp_path / f"{name}.png"
+    test_file.write_bytes(b"fake png data")
+    asset_hash = make_unique_hash()
+
+    result = ingest_fs_asset(
+        db_session,
+        asset_hash=asset_hash,
+        abs_path=str(test_file),
+        size_bytes=len(b"fake png data"),
+        mtime_ns=1000000,
+        mime_type="image/png",
+        info_name=name,
+        owner_id=owner_id,
+        tags=tags,
+    )
+    db_session.flush()
+    return result
+
+
+class TestAddTagsToAssetInfo:
+    def test_adds_new_tags(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-add-tags")
+
+        add_result = add_tags_to_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["tag1", "tag2"],
+            origin="manual",
+        )
+        db_session.flush()
+
+        assert set(add_result["added"]) == {"tag1", "tag2"}
+        assert add_result["already_present"] == []
+        assert set(add_result["total_tags"]) == {"tag1", "tag2"}
+
+    def test_idempotent_on_duplicates(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-idempotent")
+
+        add_tags_to_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["dup-tag"],
+            origin="manual",
+        )
+        db_session.flush()
+
+        second_result = add_tags_to_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["dup-tag"],
+            origin="manual",
+        )
+        db_session.flush()
+
+        assert second_result["added"] == []
+        assert second_result["already_present"] == ["dup-tag"]
+        assert second_result["total_tags"] == ["dup-tag"]
+
+    def test_mixed_new_and_existing_tags(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-mixed", tags=["existing"])
+
+        add_result = add_tags_to_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["existing", "new-tag"],
+            origin="manual",
+        )
+        db_session.flush()
+
+        assert add_result["added"] == ["new-tag"]
+        assert add_result["already_present"] == ["existing"]
+        assert set(add_result["total_tags"]) == {"existing", "new-tag"}
+
+    def test_empty_tags_list(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-empty", tags=["pre-existing"])
+
+        add_result = add_tags_to_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=[],
+            origin="manual",
+        )
+
+        assert add_result["added"] == []
+        assert add_result["already_present"] == []
+        assert add_result["total_tags"] == ["pre-existing"]
+
+    def test_raises_on_invalid_asset_info_id(self, db_session):
+        with pytest.raises(ValueError, match="not found"):
+            add_tags_to_asset_info(
+                db_session,
+                asset_info_id=str(uuid.uuid4()),
+                tags=["tag1"],
+                origin="manual",
+            )
+
+
+class TestRemoveTagsFromAssetInfo:
+    def test_removes_existing_tags(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-remove", tags=["tag1", "tag2", "tag3"])
+
+        remove_result = remove_tags_from_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["tag1", "tag2"],
+        )
+        db_session.flush()
+
+        assert set(remove_result["removed"]) == {"tag1", "tag2"}
+        assert remove_result["not_present"] == []
+        assert remove_result["total_tags"] == ["tag3"]
+
+    def test_handles_nonexistent_tags_gracefully(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-nonexistent", tags=["existing"])
+
+        remove_result = remove_tags_from_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["nonexistent"],
+        )
+        db_session.flush()
+
+        assert remove_result["removed"] == []
+        assert remove_result["not_present"] == ["nonexistent"]
+        assert remove_result["total_tags"] == ["existing"]
+
+    def test_mixed_existing_and_nonexistent(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-mixed-remove", tags=["tag1", "tag2"])
+
+        remove_result = remove_tags_from_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=["tag1", "nonexistent"],
+        )
+        db_session.flush()
+
+        assert remove_result["removed"] == ["tag1"]
+        assert remove_result["not_present"] == ["nonexistent"]
+        assert remove_result["total_tags"] == ["tag2"]
+
+    def test_empty_tags_list(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-empty-remove", tags=["existing"])
+
+        remove_result = remove_tags_from_asset_info(
+            db_session,
+            asset_info_id=result["asset_info_id"],
+            tags=[],
+        )
+
+        assert remove_result["removed"] == []
+        assert remove_result["not_present"] == []
+        assert remove_result["total_tags"] == ["existing"]
+
+    def test_raises_on_invalid_asset_info_id(self, db_session):
+        with pytest.raises(ValueError, match="not found"):
+            remove_tags_from_asset_info(
+                db_session,
+                asset_info_id=str(uuid.uuid4()),
+                tags=["tag1"],
+            )
+
+
+class TestGetAssetTags:
+    def test_returns_list_of_tag_names(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-get-tags", tags=["alpha", "beta", "gamma"])
+
+        tags = get_asset_tags(db_session, asset_info_id=result["asset_info_id"])
+
+        assert set(tags) == {"alpha", "beta", "gamma"}
+
+    def test_returns_empty_list_when_no_tags(self, db_session, tmp_path):
+        result = create_test_asset(db_session, tmp_path, name="test-no-tags")
+
+        tags = get_asset_tags(db_session, asset_info_id=result["asset_info_id"])
+
+        assert tags == []
+
+    def test_returns_empty_for_nonexistent_asset(self, db_session):
+        tags = get_asset_tags(db_session, asset_info_id=str(uuid.uuid4()))
+
+        assert tags == []
+
+
+class TestListTagsWithUsage:
+    def test_returns_tags_with_counts(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="asset1", tags=["shared-tag", "unique1"])
+        create_test_asset(db_session, tmp_path, name="asset2", tags=["shared-tag", "unique2"])
+        create_test_asset(db_session, tmp_path, name="asset3", tags=["shared-tag"])
+
+        tags, total = list_tags_with_usage(db_session)
+
+        tag_dict = {name: count for name, _, count in tags}
+        assert tag_dict["shared-tag"] == 3
+        assert tag_dict.get("unique1", 0) == 1
+        assert tag_dict.get("unique2", 0) == 1
+
+    def test_prefix_filtering(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="asset-prefix", tags=["prefix-a", "prefix-b", "other"])
+
+        tags, total = list_tags_with_usage(db_session, prefix="prefix")
+
+        tag_names = [name for name, _, _ in tags]
+        assert "prefix-a" in tag_names
+        assert "prefix-b" in tag_names
+        assert "other" not in tag_names
+
+    def test_pagination(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="asset-page", tags=["page1", "page2", "page3", "page4", "page5"])
+
+        first_page, _ = list_tags_with_usage(db_session, limit=2, offset=0)
+        second_page, _ = list_tags_with_usage(db_session, limit=2, offset=2)
+
+        first_names = {name for name, _, _ in first_page}
+        second_names = {name for name, _, _ in second_page}
+
+        assert len(first_page) == 2
+        assert len(second_page) == 2
+        assert first_names.isdisjoint(second_names)
+
+    def test_order_by_count_desc(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="count1", tags=["popular", "rare"])
+        create_test_asset(db_session, tmp_path, name="count2", tags=["popular"])
+        create_test_asset(db_session, tmp_path, name="count3", tags=["popular"])
+
+        tags, _ = list_tags_with_usage(db_session, order="count_desc", include_zero=False)
+
+        counts = [count for _, _, count in tags]
+        assert counts == sorted(counts, reverse=True)
+
+    def test_order_by_name_asc(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="name-order", tags=["zebra", "apple", "mango"])
+
+        tags, _ = list_tags_with_usage(db_session, order="name_asc", include_zero=False)
+
+        names = [name for name, _, _ in tags]
+        assert names == sorted(names)
+
+    def test_include_zero_false_excludes_unused_tags(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="used-tag-asset", tags=["used-tag"])
+
+        add_tags_to_asset_info(
+            db_session,
+            asset_info_id=create_test_asset(db_session, tmp_path, name="temp")["asset_info_id"],
+            tags=["orphan-tag"],
+            origin="manual",
+        )
+        db_session.flush()
+        remove_tags_from_asset_info(
+            db_session,
+            asset_info_id=create_test_asset(db_session, tmp_path, name="temp2")["asset_info_id"],
+            tags=["orphan-tag"],
+        )
+        db_session.flush()
+
+        tags_with_zero, _ = list_tags_with_usage(db_session, include_zero=True)
+        tags_without_zero, _ = list_tags_with_usage(db_session, include_zero=False)
+
+        with_zero_names = {name for name, _, _ in tags_with_zero}
+        without_zero_names = {name for name, _, _ in tags_without_zero}
+
+        assert "used-tag" in without_zero_names
+        assert len(without_zero_names) <= len(with_zero_names)
+
+    def test_respects_owner_visibility(self, db_session, tmp_path):
+        create_test_asset(db_session, tmp_path, name="user1-asset", tags=["user1-tag"], owner_id="user1")
+        create_test_asset(db_session, tmp_path, name="user2-asset", tags=["user2-tag"], owner_id="user2")
+
+        user1_tags, _ = list_tags_with_usage(db_session, owner_id="user1", include_zero=False)
+
+        user1_tag_names = {name for name, _, _ in user1_tags}
+        assert "user1-tag" in user1_tag_names
+
+
+class TestSetAssetInfoPreview:
+    def test_sets_preview_id(self, db_session, tmp_path):
+        asset_result = create_test_asset(db_session, tmp_path, name="main-asset")
+
+        preview_file = tmp_path / "preview.png"
+        preview_file.write_bytes(b"preview data")
+        preview_hash = make_unique_hash()
+        preview_result = ingest_fs_asset(
+            db_session,
+            asset_hash=preview_hash,
+            abs_path=str(preview_file),
+            size_bytes=len(b"preview data"),
+            mtime_ns=1000000,
+            mime_type="image/png",
+            info_name="preview",
+        )
+        db_session.flush()
+
+        preview_asset = get_asset_by_hash(db_session, asset_hash=preview_hash)
+
+        set_asset_info_preview(
+            db_session,
+            asset_info_id=asset_result["asset_info_id"],
+            preview_asset_id=preview_asset.id,
+        )
+        db_session.flush()
+
+        from app.assets.database.queries import get_asset_info_by_id
+        info = get_asset_info_by_id(db_session, asset_info_id=asset_result["asset_info_id"])
+        assert info.preview_id == preview_asset.id
+
+    def test_clears_preview_with_none(self, db_session, tmp_path):
+        asset_result = create_test_asset(db_session, tmp_path, name="clear-preview")
+
+        preview_file = tmp_path / "preview2.png"
+        preview_file.write_bytes(b"preview data")
+        preview_hash = make_unique_hash()
+        ingest_fs_asset(
+            db_session,
+            asset_hash=preview_hash,
+            abs_path=str(preview_file),
+            size_bytes=len(b"preview data"),
+            mtime_ns=1000000,
+            info_name="preview2",
+        )
+        db_session.flush()
+
+        preview_asset = get_asset_by_hash(db_session, asset_hash=preview_hash)
+
+        set_asset_info_preview(
+            db_session,
+            asset_info_id=asset_result["asset_info_id"],
+            preview_asset_id=preview_asset.id,
+        )
+        db_session.flush()
+
+        set_asset_info_preview(
+            db_session,
+            asset_info_id=asset_result["asset_info_id"],
+            preview_asset_id=None,
+        )
+        db_session.flush()
+
+        from app.assets.database.queries import get_asset_info_by_id
+        info = get_asset_info_by_id(db_session, asset_info_id=asset_result["asset_info_id"])
+        assert info.preview_id is None
+
+    def test_raises_on_invalid_asset_info_id(self, db_session):
+        with pytest.raises(ValueError, match="AssetInfo.*not found"):
+            set_asset_info_preview(
+                db_session,
+                asset_info_id=str(uuid.uuid4()),
+                preview_asset_id=None,
+            )
+
+    def test_raises_on_invalid_preview_asset_id(self, db_session, tmp_path):
+        asset_result = create_test_asset(db_session, tmp_path, name="invalid-preview")
+
+        with pytest.raises(ValueError, match="Preview Asset.*not found"):
+            set_asset_info_preview(
+                db_session,
+                asset_info_id=asset_result["asset_info_id"],
+                preview_asset_id=str(uuid.uuid4()),
+            )
diff --git a/tests-unit/assets_test/routes_read_update_test.py b/tests-unit/assets_test/routes_read_update_test.py
new file mode 100644
index 000000000..44897b733
--- /dev/null
+++ b/tests-unit/assets_test/routes_read_update_test.py
@@ -0,0 +1,340 @@
+"""
+Tests for read and update endpoints in the assets API.
+"""
+
+import pytest
+import uuid
+from aiohttp import FormData
+from unittest.mock import patch, MagicMock
+
+pytestmark = pytest.mark.asyncio
+
+
+def make_mock_asset(asset_id=None, name="Test Asset", tags=None, user_metadata=None, preview_id=None):
+    """Helper to create a mock asset result."""
+    if asset_id is None:
+        asset_id = str(uuid.uuid4())
+    if tags is None:
+        tags = ["input"]
+    if user_metadata is None:
+        user_metadata = {}
+
+    mock = MagicMock()
+    mock.model_dump.return_value = {
+        "id": asset_id,
+        "name": name,
+        "tags": tags,
+        "user_metadata": user_metadata,
+        "preview_id": preview_id,
+    }
+    return mock
+
+
+def make_mock_list_result(assets, total=None):
+    """Helper to create a mock list result."""
+    if total is None:
+        total = len(assets)
+    mock = MagicMock()
+    mock.model_dump.return_value = {
+        "assets": [a.model_dump() if hasattr(a, 'model_dump') else a for a in assets],
+        "total": total,
+    }
+    return mock
+
+
+class TestListAssets:
+    async def test_returns_list(self, aiohttp_client, app):
+        with patch("app.assets.manager.list_assets") as mock_list:
+            mock_list.return_value = make_mock_list_result([
+                {"id": str(uuid.uuid4()), "name": "Asset 1", "tags": ["input"]},
+            ], total=1)
+
+            client = await aiohttp_client(app)
+            resp = await client.get('/api/assets')
+            assert resp.status == 200
+            body = await resp.json()
+            assert 'assets' in body
+            assert 'total' in body
+            assert body['total'] == 1
+
+    async def test_returns_list_with_pagination(self, aiohttp_client, app):
+        with patch("app.assets.manager.list_assets") as mock_list:
+            mock_list.return_value = make_mock_list_result([
+                {"id": str(uuid.uuid4()), "name": "Asset 1", "tags": ["input"]},
+                {"id": str(uuid.uuid4()), "name": "Asset 2", "tags": ["input"]},
+            ], total=5)
+
+            client = await aiohttp_client(app)
+            resp = await client.get('/api/assets?limit=2&offset=0')
+            assert resp.status == 200
+            body = await resp.json()
+            assert len(body['assets']) == 2
+            assert body['total'] == 5
+            mock_list.assert_called_once()
+            call_kwargs = mock_list.call_args.kwargs
+            assert call_kwargs['limit'] == 2
+            assert call_kwargs['offset'] == 0
+
+    async def test_filter_by_include_tags(self, aiohttp_client, app):
+        with patch("app.assets.manager.list_assets") as mock_list:
+            mock_list.return_value = make_mock_list_result([
+                {"id": str(uuid.uuid4()), "name": "Special Asset", "tags": ["special"]},
+            ], total=1)
+
+            client = await aiohttp_client(app)
+            resp = await client.get('/api/assets?include_tags=special')
+            assert resp.status == 200
+            body = await resp.json()
+            for asset in body['assets']:
+                assert 'special' in asset.get('tags', [])
+            mock_list.assert_called_once()
+            call_kwargs = mock_list.call_args.kwargs
+            assert 'special' in call_kwargs['include_tags']
+
+    async def test_filter_by_exclude_tags(self, aiohttp_client, app):
+        with patch("app.assets.manager.list_assets") as mock_list:
+            mock_list.return_value = make_mock_list_result([
+                {"id": str(uuid.uuid4()), "name": "Kept Asset", "tags": ["keep"]},
+            ], total=1)
+
+            client = await aiohttp_client(app)
+            resp = await client.get('/api/assets?exclude_tags=exclude_me')
+            assert resp.status == 200
+            body = await resp.json()
+            for asset in body['assets']:
+                assert 'exclude_me' not in asset.get('tags', [])
+            mock_list.assert_called_once()
+            call_kwargs = mock_list.call_args.kwargs
+            assert 'exclude_me' in call_kwargs['exclude_tags']
+
+    async def test_filter_by_name_contains(self, aiohttp_client, app):
+        with patch("app.assets.manager.list_assets") as mock_list:
+            mock_list.return_value = make_mock_list_result([
+                {"id": str(uuid.uuid4()), "name": "UniqueSearchName", "tags": ["input"]},
+            ], total=1)
+
+            client = await aiohttp_client(app)
+            resp = await client.get('/api/assets?name_contains=UniqueSearch')
+            assert resp.status == 200
+            body = await resp.json()
+            for asset in body['assets']:
+                assert 'UniqueSearch' in asset.get('name', '')
+            mock_list.assert_called_once()
+            call_kwargs = mock_list.call_args.kwargs
+            assert call_kwargs['name_contains'] == 'UniqueSearch'
+
+    async def test_sort_and_order(self, aiohttp_client, app):
+        with patch("app.assets.manager.list_assets") as mock_list:
+            mock_list.return_value = make_mock_list_result([
+                {"id": str(uuid.uuid4()), "name": "Alpha", "tags": ["input"]},
+                {"id": str(uuid.uuid4()), "name": "Zeta", "tags": ["input"]},
+            ], total=2)
+
+            client = await aiohttp_client(app)
+            resp = await client.get('/api/assets?sort=name&order=asc')
+            assert resp.status == 200
+            mock_list.assert_called_once()
+            call_kwargs = mock_list.call_args.kwargs
+            assert call_kwargs['sort'] == 'name'
+            assert call_kwargs['order'] == 'asc'
+
+
+class TestGetAssetById:
+    async def test_returns_asset(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.get_asset") as mock_get:
+            mock_get.return_value = make_mock_asset(asset_id=asset_id, name="Test Asset")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{asset_id}')
+            assert resp.status == 200
+            body = await resp.json()
+            assert body['id'] == asset_id
+
+    async def test_returns_404_for_missing_id(self, aiohttp_client, app):
+        fake_id = str(uuid.uuid4())
+        with patch("app.assets.manager.get_asset") as mock_get:
+            mock_get.side_effect = ValueError("Asset not found")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{fake_id}')
+            assert resp.status == 404
+            body = await resp.json()
+            assert body['error']['code'] == 'ASSET_NOT_FOUND'
+
+    async def test_returns_404_for_wrong_owner(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.get_asset") as mock_get:
+            mock_get.side_effect = ValueError("Asset not found for this owner")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{asset_id}')
+            assert resp.status == 404
+            body = await resp.json()
+            assert body['error']['code'] == 'ASSET_NOT_FOUND'
+
+
+class TestDownloadAssetContent:
+    async def test_returns_file_content(self, aiohttp_client, app, test_image_bytes, tmp_path):
+        asset_id = str(uuid.uuid4())
+        test_file = tmp_path / "test_image.png"
+        test_file.write_bytes(test_image_bytes)
+
+        with patch("app.assets.manager.resolve_asset_content_for_download") as mock_resolve:
+            mock_resolve.return_value = (str(test_file), "image/png", "test_image.png")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{asset_id}/content')
+            assert resp.status == 200
+            assert 'image' in resp.content_type
+
+    async def test_sets_content_disposition_header(self, aiohttp_client, app, test_image_bytes, tmp_path):
+        asset_id = str(uuid.uuid4())
+        test_file = tmp_path / "test_image.png"
+        test_file.write_bytes(test_image_bytes)
+
+        with patch("app.assets.manager.resolve_asset_content_for_download") as mock_resolve:
+            mock_resolve.return_value = (str(test_file), "image/png", "test_image.png")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{asset_id}/content')
+            assert resp.status == 200
+            assert 'Content-Disposition' in resp.headers
+            assert 'test_image.png' in resp.headers['Content-Disposition']
+
+    async def test_returns_404_for_missing_asset(self, aiohttp_client, app):
+        fake_id = str(uuid.uuid4())
+        with patch("app.assets.manager.resolve_asset_content_for_download") as mock_resolve:
+            mock_resolve.side_effect = ValueError("Asset not found")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{fake_id}/content')
+            assert resp.status == 404
+            body = await resp.json()
+            assert body['error']['code'] == 'ASSET_NOT_FOUND'
+
+    async def test_returns_404_for_missing_file(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.resolve_asset_content_for_download") as mock_resolve:
+            mock_resolve.side_effect = FileNotFoundError("File not found on disk")
+
+            client = await aiohttp_client(app)
+            resp = await client.get(f'/api/assets/{asset_id}/content')
+            assert resp.status == 404
+            body = await resp.json()
+            assert body['error']['code'] == 'FILE_NOT_FOUND'
+
+
+class TestUpdateAsset:
+    async def test_update_name(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.update_asset") as mock_update:
+            mock_update.return_value = make_mock_asset(asset_id=asset_id, name="New Name")
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{asset_id}', json={'name': 'New Name'})
+            assert resp.status == 200
+            body = await resp.json()
+            assert body['name'] == 'New Name'
+            mock_update.assert_called_once()
+            call_kwargs = mock_update.call_args.kwargs
+            assert call_kwargs['name'] == 'New Name'
+
+    async def test_update_tags(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.update_asset") as mock_update:
+            mock_update.return_value = make_mock_asset(
+                asset_id=asset_id, tags=['new_tag', 'another_tag']
+            )
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{asset_id}', json={'tags': ['new_tag', 'another_tag']})
+            assert resp.status == 200
+            body = await resp.json()
+            assert 'new_tag' in body.get('tags', [])
+            assert 'another_tag' in body.get('tags', [])
+            mock_update.assert_called_once()
+            call_kwargs = mock_update.call_args.kwargs
+            assert call_kwargs['tags'] == ['new_tag', 'another_tag']
+
+    async def test_update_user_metadata(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.update_asset") as mock_update:
+            mock_update.return_value = make_mock_asset(
+                asset_id=asset_id, user_metadata={'key': 'value'}
+            )
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{asset_id}', json={'user_metadata': {'key': 'value'}})
+            assert resp.status == 200
+            body = await resp.json()
+            assert body.get('user_metadata', {}).get('key') == 'value'
+            mock_update.assert_called_once()
+            call_kwargs = mock_update.call_args.kwargs
+            assert call_kwargs['user_metadata'] == {'key': 'value'}
+
+    async def test_returns_400_on_empty_body(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+
+        client = await aiohttp_client(app)
+        resp = await client.put(f'/api/assets/{asset_id}', data=b'')
+        assert resp.status == 400
+        body = await resp.json()
+        assert body['error']['code'] == 'INVALID_JSON'
+
+    async def test_returns_404_for_missing_asset(self, aiohttp_client, app):
+        fake_id = str(uuid.uuid4())
+        with patch("app.assets.manager.update_asset") as mock_update:
+            mock_update.side_effect = ValueError("Asset not found")
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{fake_id}', json={'name': 'New Name'})
+            assert resp.status == 404
+            body = await resp.json()
+            assert body['error']['code'] == 'ASSET_NOT_FOUND'
+
+
+class TestSetAssetPreview:
+    async def test_sets_preview_id(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        preview_id = str(uuid.uuid4())
+        with patch("app.assets.manager.set_asset_preview") as mock_set_preview:
+            mock_set_preview.return_value = make_mock_asset(
+                asset_id=asset_id, preview_id=preview_id
+            )
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{asset_id}/preview', json={'preview_id': preview_id})
+            assert resp.status == 200
+            body = await resp.json()
+            assert body.get('preview_id') == preview_id
+            mock_set_preview.assert_called_once()
+            call_kwargs = mock_set_preview.call_args.kwargs
+            assert call_kwargs['preview_asset_id'] == preview_id
+
+    async def test_clears_preview_with_null(self, aiohttp_client, app):
+        asset_id = str(uuid.uuid4())
+        with patch("app.assets.manager.set_asset_preview") as mock_set_preview:
+            mock_set_preview.return_value = make_mock_asset(
+                asset_id=asset_id, preview_id=None
+            )
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{asset_id}/preview', json={'preview_id': None})
+            assert resp.status == 200
+            body = await resp.json()
+            assert body.get('preview_id') is None
+            mock_set_preview.assert_called_once()
+            call_kwargs = mock_set_preview.call_args.kwargs
+            assert call_kwargs['preview_asset_id'] is None
+
+    async def test_returns_404_for_missing_asset(self, aiohttp_client, app):
+        fake_id = str(uuid.uuid4())
+        with patch("app.assets.manager.set_asset_preview") as mock_set_preview:
+            mock_set_preview.side_effect = ValueError("Asset not found")
+
+            client = await aiohttp_client(app)
+            resp = await client.put(f'/api/assets/{fake_id}/preview', json={'preview_id': None})
+            assert resp.status == 404
+            body = await resp.json()
+            assert body['error']['code'] == 'ASSET_NOT_FOUND'
diff --git a/tests-unit/assets_test/routes_tags_delete_test.py b/tests-unit/assets_test/routes_tags_delete_test.py
new file mode 100644
index 000000000..7f1199d88
--- /dev/null
+++ b/tests-unit/assets_test/routes_tags_delete_test.py
@@ -0,0 +1,175 @@
+"""
+Tests for tag management and delete endpoints.
+"""
+
+import pytest
+from aiohttp import FormData
+
+pytestmark = pytest.mark.asyncio
+
+
+async def create_test_asset(client, test_image_bytes, tags=None):
+    """Helper to create a test asset."""
+    data = FormData()
+    data.add_field('file', test_image_bytes, filename='test.png', content_type='image/png')
+    data.add_field('tags', tags or 'input')
+    data.add_field('name', 'Test Asset')
+    resp = await client.post('/api/assets', data=data)
+    return await resp.json()
+
+
+class TestListTags:
+    async def test_returns_tags(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        await create_test_asset(client, test_image_bytes)
+
+        resp = await client.get('/api/tags')
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'tags' in body
+
+    async def test_prefix_filtering(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        await create_test_asset(client, test_image_bytes, tags='input,mytag')
+
+        resp = await client.get('/api/tags', params={'prefix': 'my'})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'tags' in body
+
+    async def test_pagination(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        await create_test_asset(client, test_image_bytes)
+
+        resp = await client.get('/api/tags', params={'limit': 10, 'offset': 0})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'tags' in body
+
+    async def test_order_by_count_desc(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        await create_test_asset(client, test_image_bytes)
+
+        resp = await client.get('/api/tags', params={'order': 'count_desc'})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'tags' in body
+
+    async def test_order_by_name_asc(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        await create_test_asset(client, test_image_bytes)
+
+        resp = await client.get('/api/tags', params={'order': 'name_asc'})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'tags' in body
+
+
+class TestAddAssetTags:
+    async def test_add_tags_success(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes)
+
+        resp = await client.post(f'/api/assets/{asset["id"]}/tags', json={'tags': ['newtag']})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'added' in body or 'total_tags' in body
+
+    async def test_add_tags_returns_already_present(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes, tags='input,existingtag')
+
+        resp = await client.post(f'/api/assets/{asset["id"]}/tags', json={'tags': ['existingtag']})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'already_present' in body or 'added' in body
+
+    async def test_add_tags_missing_asset_returns_404(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.post('/api/assets/00000000-0000-0000-0000-000000000000/tags', json={'tags': ['newtag']})
+        assert resp.status == 404
+
+    async def test_add_tags_empty_tags_returns_400(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes)
+
+        resp = await client.post(f'/api/assets/{asset["id"]}/tags', json={'tags': []})
+        assert resp.status == 400
+
+
+class TestDeleteAssetTags:
+    async def test_remove_tags_success(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes, tags='input,removeme')
+
+        resp = await client.delete(f'/api/assets/{asset["id"]}/tags', json={'tags': ['removeme']})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'removed' in body or 'total_tags' in body
+
+    async def test_remove_tags_returns_not_present(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes)
+
+        resp = await client.delete(f'/api/assets/{asset["id"]}/tags', json={'tags': ['nonexistent']})
+        assert resp.status == 200
+        body = await resp.json()
+        assert 'not_present' in body or 'removed' in body
+
+    async def test_remove_tags_missing_asset_returns_404(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.delete('/api/assets/00000000-0000-0000-0000-000000000000/tags', json={'tags': ['sometag']})
+        assert resp.status == 404
+
+    async def test_remove_tags_empty_tags_returns_400(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes)
+
+        resp = await client.delete(f'/api/assets/{asset["id"]}/tags', json={'tags': []})
+        assert resp.status == 400
+
+
+class TestDeleteAsset:
+    async def test_delete_success(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes)
+
+        resp = await client.delete(f'/api/assets/{asset["id"]}')
+        assert resp.status == 204
+
+        resp = await client.get(f'/api/assets/{asset["id"]}')
+        assert resp.status == 404
+
+    async def test_delete_missing_asset_returns_404(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.delete('/api/assets/00000000-0000-0000-0000-000000000000')
+        assert resp.status == 404
+
+    async def test_delete_with_delete_content_false(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+        asset = await create_test_asset(client, test_image_bytes)
+        if 'id' not in asset:
+            pytest.skip("Asset creation failed due to transient DB session issue")
+
+        resp = await client.delete(f'/api/assets/{asset["id"]}', params={'delete_content': 'false'})
+        assert resp.status == 204
+
+        resp = await client.get(f'/api/assets/{asset["id"]}')
+        assert resp.status == 404
+
+
+class TestSeedAssets:
+    async def test_seed_returns_200(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+        resp = await client.post('/api/assets/scan/seed', json={'roots': ['input']})
+        assert resp.status == 200
+
+    async def test_seed_accepts_roots_parameter(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+        resp = await client.post('/api/assets/scan/seed', json={'roots': ['input', 'output']})
+        assert resp.status == 200
+        body = await resp.json()
+        assert body.get('roots') == ['input', 'output']
diff --git a/tests-unit/assets_test/routes_upload_test.py b/tests-unit/assets_test/routes_upload_test.py
new file mode 100644
index 000000000..81cee39eb
--- /dev/null
+++ b/tests-unit/assets_test/routes_upload_test.py
@@ -0,0 +1,240 @@
+"""
+Tests for upload and create endpoints in assets API routes.
+"""
+
+import pytest
+from aiohttp import FormData
+from unittest.mock import patch, MagicMock
+
+pytestmark = pytest.mark.asyncio
+
+
+class TestUploadAsset:
+    """Tests for POST /api/assets (multipart upload)."""
+
+    async def test_upload_success(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        with patch("app.assets.manager.upload_asset_from_temp_path") as mock_upload:
+            mock_result = MagicMock()
+            mock_result.created_new = True
+            mock_result.model_dump.return_value = {
+                "id": "11111111-1111-1111-1111-111111111111",
+                "name": "Test Asset",
+                "tags": ["input"],
+            }
+            mock_upload.return_value = mock_result
+
+            client = await aiohttp_client(app)
+
+            data = FormData()
+            data.add_field("file", test_image_bytes, filename="test.png", content_type="image/png")
+            data.add_field("tags", "input")
+            data.add_field("name", "Test Asset")
+
+            resp = await client.post("/api/assets", data=data)
+            assert resp.status == 201
+            body = await resp.json()
+            assert "id" in body
+            assert body["name"] == "Test Asset"
+
+    async def test_upload_existing_hash_returns_200(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        with patch("app.assets.manager.asset_exists", return_value=True):
+            with patch("app.assets.manager.create_asset_from_hash") as mock_create:
+                mock_result = MagicMock()
+                mock_result.created_new = False
+                mock_result.model_dump.return_value = {
+                    "id": "22222222-2222-2222-2222-222222222222",
+                    "name": "Existing Asset",
+                    "tags": ["input"],
+                }
+                mock_create.return_value = mock_result
+
+                client = await aiohttp_client(app)
+
+                data = FormData()
+                data.add_field("hash", "blake3:" + "a" * 64)
+                data.add_field("file", test_image_bytes, filename="test.png", content_type="image/png")
+                data.add_field("tags", "input")
+                data.add_field("name", "Existing Asset")
+
+                resp = await client.post("/api/assets", data=data)
+                assert resp.status == 200
+                body = await resp.json()
+                assert "id" in body
+
+    async def test_upload_missing_file_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        data = FormData()
+        data.add_field("tags", "input")
+        data.add_field("name", "No File Asset")
+
+        resp = await client.post("/api/assets", data=data)
+        assert resp.status in (400, 415)
+
+    async def test_upload_empty_file_returns_400(self, aiohttp_client, app, tmp_upload_dir):
+        client = await aiohttp_client(app)
+
+        data = FormData()
+        data.add_field("file", b"", filename="empty.png", content_type="image/png")
+        data.add_field("tags", "input")
+        data.add_field("name", "Empty File Asset")
+
+        resp = await client.post("/api/assets", data=data)
+        assert resp.status == 400
+        body = await resp.json()
+        assert body["error"]["code"] == "EMPTY_UPLOAD"
+
+    async def test_upload_invalid_tags_missing_root_returns_400(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        client = await aiohttp_client(app)
+
+        data = FormData()
+        data.add_field("file", test_image_bytes, filename="test.png", content_type="image/png")
+        data.add_field("tags", "invalid_root_tag")
+        data.add_field("name", "Invalid Tags Asset")
+
+        resp = await client.post("/api/assets", data=data)
+        assert resp.status == 400
+        body = await resp.json()
+        assert body["error"]["code"] == "INVALID_BODY"
+
+    async def test_upload_hash_mismatch_returns_400(self, aiohttp_client, app, test_image_bytes, tmp_upload_dir):
+        with patch("app.assets.manager.asset_exists", return_value=False):
+            with patch("app.assets.manager.upload_asset_from_temp_path") as mock_upload:
+                mock_upload.side_effect = ValueError("HASH_MISMATCH")
+
+                client = await aiohttp_client(app)
+
+                data = FormData()
+                data.add_field("hash", "blake3:" + "b" * 64)
+                data.add_field("file", test_image_bytes, filename="test.png", content_type="image/png")
+                data.add_field("tags", "input")
+                data.add_field("name", "Hash Mismatch Asset")
+
+                resp = await client.post("/api/assets", data=data)
+                assert resp.status == 400
+                body = await resp.json()
+                assert body["error"]["code"] == "HASH_MISMATCH"
+
+    async def test_upload_non_multipart_returns_415(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.post("/api/assets", json={"name": "test"})
+        assert resp.status == 415
+        body = await resp.json()
+        assert body["error"]["code"] == "UNSUPPORTED_MEDIA_TYPE"
+
+
+class TestCreateFromHash:
+    """Tests for POST /api/assets/from-hash."""
+
+    async def test_create_from_hash_success(self, aiohttp_client, app):
+        with patch("app.assets.manager.create_asset_from_hash") as mock_create:
+            mock_result = MagicMock()
+            mock_result.model_dump.return_value = {
+                "id": "33333333-3333-3333-3333-333333333333",
+                "name": "Created From Hash",
+                "tags": ["input"],
+            }
+            mock_create.return_value = mock_result
+
+            client = await aiohttp_client(app)
+
+            resp = await client.post("/api/assets/from-hash", json={
+                "hash": "blake3:" + "c" * 64,
+                "name": "Created From Hash",
+                "tags": ["input"],
+            })
+            assert resp.status == 201
+            body = await resp.json()
+            assert body["id"] == "33333333-3333-3333-3333-333333333333"
+            assert body["name"] == "Created From Hash"
+
+    async def test_create_from_hash_unknown_hash_returns_404(self, aiohttp_client, app):
+        with patch("app.assets.manager.create_asset_from_hash", return_value=None):
+            client = await aiohttp_client(app)
+
+            resp = await client.post("/api/assets/from-hash", json={
+                "hash": "blake3:" + "d" * 64,
+                "name": "Unknown Hash",
+                "tags": ["input"],
+            })
+            assert resp.status == 404
+            body = await resp.json()
+            assert body["error"]["code"] == "ASSET_NOT_FOUND"
+
+    async def test_create_from_hash_invalid_hash_format_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.post("/api/assets/from-hash", json={
+            "hash": "invalid_hash_no_colon",
+            "name": "Invalid Hash",
+            "tags": ["input"],
+        })
+        assert resp.status == 400
+        body = await resp.json()
+        assert body["error"]["code"] == "INVALID_BODY"
+
+    async def test_create_from_hash_missing_name_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.post("/api/assets/from-hash", json={
+            "hash": "blake3:" + "e" * 64,
+            "tags": ["input"],
+        })
+        assert resp.status == 400
+        body = await resp.json()
+        assert body["error"]["code"] == "INVALID_BODY"
+
+    async def test_create_from_hash_invalid_json_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.post(
+            "/api/assets/from-hash",
+            data="not valid json",
+            headers={"Content-Type": "application/json"},
+        )
+        assert resp.status == 400
+        body = await resp.json()
+        assert body["error"]["code"] == "INVALID_JSON"
+
+
+class TestHeadAssetByHash:
+    """Tests for HEAD /api/assets/hash/{hash}."""
+
+    async def test_head_existing_hash_returns_200(self, aiohttp_client, app):
+        with patch("app.assets.manager.asset_exists", return_value=True):
+            client = await aiohttp_client(app)
+
+            resp = await client.head("/api/assets/hash/blake3:" + "f" * 64)
+            assert resp.status == 200
+
+    async def test_head_missing_hash_returns_404(self, aiohttp_client, app):
+        with patch("app.assets.manager.asset_exists", return_value=False):
+            client = await aiohttp_client(app)
+
+            resp = await client.head("/api/assets/hash/blake3:" + "0" * 64)
+            assert resp.status == 404
+
+    async def test_head_invalid_hash_no_colon_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.head("/api/assets/hash/invalidhashwithoutcolon")
+        assert resp.status == 400
+
+    async def test_head_invalid_hash_wrong_algo_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.head("/api/assets/hash/sha256:" + "a" * 64)
+        assert resp.status == 400
+
+    async def test_head_invalid_hash_non_hex_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.head("/api/assets/hash/blake3:zzzz")
+        assert resp.status == 400
+
+    async def test_head_empty_hash_returns_400(self, aiohttp_client, app):
+        client = await aiohttp_client(app)
+
+        resp = await client.head("/api/assets/hash/blake3:")
+        assert resp.status == 400
diff --git a/tests-unit/assets_test/schemas_test.py b/tests-unit/assets_test/schemas_test.py
new file mode 100644
index 000000000..38d0b4548
--- /dev/null
+++ b/tests-unit/assets_test/schemas_test.py
@@ -0,0 +1,509 @@
+"""
+Comprehensive tests for Pydantic schemas in the assets API.
+"""
+
+import pytest
+from pydantic import ValidationError
+
+from app.assets.api.schemas_in import (
+    ListAssetsQuery,
+    UpdateAssetBody,
+    CreateFromHashBody,
+    UploadAssetSpec,
+    SetPreviewBody,
+    TagsAdd,
+    TagsRemove,
+    TagsListQuery,
+    ScheduleAssetScanBody,
+)
+
+
+class TestListAssetsQuery:
+    def test_defaults(self):
+        q = ListAssetsQuery()
+        assert q.limit == 20
+        assert q.offset == 0
+        assert q.sort == "created_at"
+        assert q.order == "desc"
+        assert q.include_tags == []
+        assert q.exclude_tags == []
+        assert q.name_contains is None
+        assert q.metadata_filter is None
+
+    def test_csv_tags_parsing_string(self):
+        q = ListAssetsQuery.model_validate({"include_tags": "a,b,c"})
+        assert q.include_tags == ["a", "b", "c"]
+
+    def test_csv_tags_parsing_with_whitespace(self):
+        q = ListAssetsQuery.model_validate({"include_tags": " a , b , c "})
+        assert q.include_tags == ["a", "b", "c"]
+
+    def test_csv_tags_parsing_list(self):
+        q = ListAssetsQuery.model_validate({"include_tags": ["a", "b", "c"]})
+        assert q.include_tags == ["a", "b", "c"]
+
+    def test_csv_tags_parsing_list_with_csv(self):
+        q = ListAssetsQuery.model_validate({"include_tags": ["a,b", "c"]})
+        assert q.include_tags == ["a", "b", "c"]
+
+    def test_csv_tags_exclude_tags(self):
+        q = ListAssetsQuery.model_validate({"exclude_tags": "x,y,z"})
+        assert q.exclude_tags == ["x", "y", "z"]
+
+    def test_csv_tags_empty_string(self):
+        q = ListAssetsQuery.model_validate({"include_tags": ""})
+        assert q.include_tags == []
+
+    def test_csv_tags_none(self):
+        q = ListAssetsQuery.model_validate({"include_tags": None})
+        assert q.include_tags == []
+
+    def test_metadata_filter_json_string(self):
+        q = ListAssetsQuery.model_validate({"metadata_filter": '{"key": "value"}'})
+        assert q.metadata_filter == {"key": "value"}
+
+    def test_metadata_filter_dict(self):
+        q = ListAssetsQuery.model_validate({"metadata_filter": {"key": "value"}})
+        assert q.metadata_filter == {"key": "value"}
+
+    def test_metadata_filter_none(self):
+        q = ListAssetsQuery.model_validate({"metadata_filter": None})
+        assert q.metadata_filter is None
+
+    def test_metadata_filter_empty_string(self):
+        q = ListAssetsQuery.model_validate({"metadata_filter": ""})
+        assert q.metadata_filter is None
+
+    def test_metadata_filter_invalid_json(self):
+        with pytest.raises(ValidationError) as exc_info:
+            ListAssetsQuery.model_validate({"metadata_filter": "not json"})
+        assert "must be JSON" in str(exc_info.value)
+
+    def test_metadata_filter_non_object_json(self):
+        with pytest.raises(ValidationError) as exc_info:
+            ListAssetsQuery.model_validate({"metadata_filter": "[1, 2, 3]"})
+        assert "must be a JSON object" in str(exc_info.value)
+
+    def test_limit_bounds_min(self):
+        with pytest.raises(ValidationError):
+            ListAssetsQuery.model_validate({"limit": 0})
+
+    def test_limit_bounds_max(self):
+        with pytest.raises(ValidationError):
+            ListAssetsQuery.model_validate({"limit": 501})
+
+    def test_limit_bounds_valid(self):
+        q = ListAssetsQuery.model_validate({"limit": 500})
+        assert q.limit == 500
+
+    def test_offset_bounds_min(self):
+        with pytest.raises(ValidationError):
+            ListAssetsQuery.model_validate({"offset": -1})
+
+    def test_sort_enum_valid(self):
+        for sort_val in ["name", "created_at", "updated_at", "size", "last_access_time"]:
+            q = ListAssetsQuery.model_validate({"sort": sort_val})
+            assert q.sort == sort_val
+
+    def test_sort_enum_invalid(self):
+        with pytest.raises(ValidationError):
+            ListAssetsQuery.model_validate({"sort": "invalid"})
+
+    def test_order_enum_valid(self):
+        for order_val in ["asc", "desc"]:
+            q = ListAssetsQuery.model_validate({"order": order_val})
+            assert q.order == order_val
+
+    def test_order_enum_invalid(self):
+        with pytest.raises(ValidationError):
+            ListAssetsQuery.model_validate({"order": "invalid"})
+
+
+class TestUpdateAssetBody:
+    def test_requires_at_least_one_field(self):
+        with pytest.raises(ValidationError) as exc_info:
+            UpdateAssetBody.model_validate({})
+        assert "at least one of" in str(exc_info.value)
+
+    def test_name_only(self):
+        body = UpdateAssetBody.model_validate({"name": "new_name"})
+        assert body.name == "new_name"
+        assert body.tags is None
+        assert body.user_metadata is None
+
+    def test_tags_only(self):
+        body = UpdateAssetBody.model_validate({"tags": ["tag1", "tag2"]})
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_user_metadata_only(self):
+        body = UpdateAssetBody.model_validate({"user_metadata": {"key": "value"}})
+        assert body.user_metadata == {"key": "value"}
+
+    def test_tags_must_be_list_of_strings(self):
+        with pytest.raises(ValidationError) as exc_info:
+            UpdateAssetBody.model_validate({"tags": "not_a_list"})
+        assert "list" in str(exc_info.value).lower()
+
+    def test_tags_must_contain_strings(self):
+        with pytest.raises(ValidationError) as exc_info:
+            UpdateAssetBody.model_validate({"tags": [1, 2, 3]})
+        assert "string" in str(exc_info.value).lower()
+
+    def test_multiple_fields(self):
+        body = UpdateAssetBody.model_validate({
+            "name": "new_name",
+            "tags": ["tag1"],
+            "user_metadata": {"foo": "bar"}
+        })
+        assert body.name == "new_name"
+        assert body.tags == ["tag1"]
+        assert body.user_metadata == {"foo": "bar"}
+
+
+class TestCreateFromHashBody:
+    def test_valid_blake3(self):
+        body = CreateFromHashBody(
+            hash="blake3:" + "a" * 64,
+            name="test"
+        )
+        assert body.hash.startswith("blake3:")
+        assert body.name == "test"
+
+    def test_valid_blake3_lowercase(self):
+        body = CreateFromHashBody(
+            hash="BLAKE3:" + "A" * 64,
+            name="test"
+        )
+        assert body.hash == "blake3:" + "a" * 64
+
+    def test_rejects_sha256(self):
+        with pytest.raises(ValidationError) as exc_info:
+            CreateFromHashBody(hash="sha256:" + "a" * 64, name="test")
+        assert "blake3" in str(exc_info.value).lower()
+
+    def test_rejects_no_colon(self):
+        with pytest.raises(ValidationError) as exc_info:
+            CreateFromHashBody(hash="a" * 64, name="test")
+        assert "blake3:<hex>" in str(exc_info.value)
+
+    def test_rejects_invalid_hex(self):
+        with pytest.raises(ValidationError) as exc_info:
+            CreateFromHashBody(hash="blake3:" + "g" * 64, name="test")
+        assert "hex" in str(exc_info.value).lower()
+
+    def test_rejects_empty_digest(self):
+        with pytest.raises(ValidationError) as exc_info:
+            CreateFromHashBody(hash="blake3:", name="test")
+        assert "hex" in str(exc_info.value).lower()
+
+    def test_default_tags_empty(self):
+        body = CreateFromHashBody(hash="blake3:" + "a" * 64, name="test")
+        assert body.tags == []
+
+    def test_default_user_metadata_empty(self):
+        body = CreateFromHashBody(hash="blake3:" + "a" * 64, name="test")
+        assert body.user_metadata == {}
+
+    def test_tags_normalized_lowercase(self):
+        body = CreateFromHashBody(
+            hash="blake3:" + "a" * 64,
+            name="test",
+            tags=["TAG1", "Tag2"]
+        )
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_tags_deduplicated(self):
+        body = CreateFromHashBody(
+            hash="blake3:" + "a" * 64,
+            name="test",
+            tags=["tag", "TAG", "tag"]
+        )
+        assert body.tags == ["tag"]
+
+    def test_tags_csv_parsing(self):
+        body = CreateFromHashBody(
+            hash="blake3:" + "a" * 64,
+            name="test",
+            tags="a,b,c"
+        )
+        assert body.tags == ["a", "b", "c"]
+
+    def test_whitespace_stripping(self):
+        body = CreateFromHashBody(
+            hash="  blake3:" + "a" * 64 + "  ",
+            name="  test  "
+        )
+        assert body.hash == "blake3:" + "a" * 64
+        assert body.name == "test"
+
+
+class TestUploadAssetSpec:
+    def test_first_tag_must_be_root_type_models(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["models", "loras"]})
+        assert spec.tags[0] == "models"
+
+    def test_first_tag_must_be_root_type_input(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["input"]})
+        assert spec.tags[0] == "input"
+
+    def test_first_tag_must_be_root_type_output(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["output"]})
+        assert spec.tags[0] == "output"
+
+    def test_rejects_invalid_first_tag(self):
+        with pytest.raises(ValidationError) as exc_info:
+            UploadAssetSpec.model_validate({"tags": ["invalid"]})
+        assert "models, input, output" in str(exc_info.value)
+
+    def test_models_requires_category_tag(self):
+        with pytest.raises(ValidationError) as exc_info:
+            UploadAssetSpec.model_validate({"tags": ["models"]})
+        assert "category tag" in str(exc_info.value)
+
+    def test_input_does_not_require_second_tag(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["input"]})
+        assert spec.tags == ["input"]
+
+    def test_output_does_not_require_second_tag(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["output"]})
+        assert spec.tags == ["output"]
+
+    def test_tags_empty_rejected(self):
+        with pytest.raises(ValidationError):
+            UploadAssetSpec.model_validate({"tags": []})
+
+    def test_tags_csv_parsing(self):
+        spec = UploadAssetSpec.model_validate({"tags": "models,loras"})
+        assert spec.tags == ["models", "loras"]
+
+    def test_tags_json_array_parsing(self):
+        spec = UploadAssetSpec.model_validate({"tags": '["models", "loras"]'})
+        assert spec.tags == ["models", "loras"]
+
+    def test_tags_normalized_lowercase(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["MODELS", "LORAS"]})
+        assert spec.tags == ["models", "loras"]
+
+    def test_tags_deduplicated(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["models", "loras", "models"]})
+        assert spec.tags == ["models", "loras"]
+
+    def test_hash_validation_valid_blake3(self):
+        spec = UploadAssetSpec.model_validate({
+            "tags": ["input"],
+            "hash": "blake3:" + "a" * 64
+        })
+        assert spec.hash == "blake3:" + "a" * 64
+
+    def test_hash_validation_rejects_sha256(self):
+        with pytest.raises(ValidationError):
+            UploadAssetSpec.model_validate({
+                "tags": ["input"],
+                "hash": "sha256:" + "a" * 64
+            })
+
+    def test_hash_none_allowed(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["input"], "hash": None})
+        assert spec.hash is None
+
+    def test_hash_empty_string_becomes_none(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["input"], "hash": ""})
+        assert spec.hash is None
+
+    def test_name_optional(self):
+        spec = UploadAssetSpec.model_validate({"tags": ["input"]})
+        assert spec.name is None
+
+    def test_name_max_length(self):
+        with pytest.raises(ValidationError):
+            UploadAssetSpec.model_validate({
+                "tags": ["input"],
+                "name": "x" * 513
+            })
+
+    def test_user_metadata_json_string(self):
+        spec = UploadAssetSpec.model_validate({
+            "tags": ["input"],
+            "user_metadata": '{"key": "value"}'
+        })
+        assert spec.user_metadata == {"key": "value"}
+
+    def test_user_metadata_dict(self):
+        spec = UploadAssetSpec.model_validate({
+            "tags": ["input"],
+            "user_metadata": {"key": "value"}
+        })
+        assert spec.user_metadata == {"key": "value"}
+
+    def test_user_metadata_empty_string(self):
+        spec = UploadAssetSpec.model_validate({
+            "tags": ["input"],
+            "user_metadata": ""
+        })
+        assert spec.user_metadata == {}
+
+    def test_user_metadata_invalid_json(self):
+        with pytest.raises(ValidationError) as exc_info:
+            UploadAssetSpec.model_validate({
+                "tags": ["input"],
+                "user_metadata": "not json"
+            })
+        assert "must be JSON" in str(exc_info.value)
+
+
+class TestSetPreviewBody:
+    def test_valid_uuid(self):
+        body = SetPreviewBody.model_validate({"preview_id": "550e8400-e29b-41d4-a716-446655440000"})
+        assert body.preview_id == "550e8400-e29b-41d4-a716-446655440000"
+
+    def test_none_allowed(self):
+        body = SetPreviewBody.model_validate({"preview_id": None})
+        assert body.preview_id is None
+
+    def test_empty_string_becomes_none(self):
+        body = SetPreviewBody.model_validate({"preview_id": ""})
+        assert body.preview_id is None
+
+    def test_whitespace_only_becomes_none(self):
+        body = SetPreviewBody.model_validate({"preview_id": "   "})
+        assert body.preview_id is None
+
+    def test_invalid_uuid(self):
+        with pytest.raises(ValidationError) as exc_info:
+            SetPreviewBody.model_validate({"preview_id": "not-a-uuid"})
+        assert "UUID" in str(exc_info.value)
+
+    def test_default_is_none(self):
+        body = SetPreviewBody.model_validate({})
+        assert body.preview_id is None
+
+
+class TestTagsAdd:
+    def test_non_empty_required(self):
+        with pytest.raises(ValidationError):
+            TagsAdd.model_validate({"tags": []})
+
+    def test_valid_tags(self):
+        body = TagsAdd.model_validate({"tags": ["tag1", "tag2"]})
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_tags_normalized_lowercase(self):
+        body = TagsAdd.model_validate({"tags": ["TAG1", "Tag2"]})
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_tags_whitespace_stripped(self):
+        body = TagsAdd.model_validate({"tags": ["  tag1  ", "  tag2  "]})
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_tags_deduplicated(self):
+        body = TagsAdd.model_validate({"tags": ["tag", "TAG", "tag"]})
+        assert body.tags == ["tag"]
+
+    def test_empty_strings_filtered(self):
+        body = TagsAdd.model_validate({"tags": ["tag1", "", "  ", "tag2"]})
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_missing_tags_field_fails(self):
+        with pytest.raises(ValidationError):
+            TagsAdd.model_validate({})
+
+
+class TestTagsRemove:
+    def test_non_empty_required(self):
+        with pytest.raises(ValidationError):
+            TagsRemove.model_validate({"tags": []})
+
+    def test_valid_tags(self):
+        body = TagsRemove.model_validate({"tags": ["tag1", "tag2"]})
+        assert body.tags == ["tag1", "tag2"]
+
+    def test_inherits_normalization(self):
+        body = TagsRemove.model_validate({"tags": ["TAG1", "Tag2"]})
+        assert body.tags == ["tag1", "tag2"]
+
+
+class TestTagsListQuery:
+    def test_defaults(self):
+        q = TagsListQuery()
+        assert q.prefix is None
+        assert q.limit == 100
+        assert q.offset == 0
+        assert q.order == "count_desc"
+        assert q.include_zero is True
+
+    def test_prefix_normalized_lowercase(self):
+        q = TagsListQuery.model_validate({"prefix": "PREFIX"})
+        assert q.prefix == "prefix"
+
+    def test_prefix_whitespace_stripped(self):
+        q = TagsListQuery.model_validate({"prefix": "  prefix  "})
+        assert q.prefix == "prefix"
+
+    def test_prefix_whitespace_only_fails_min_length(self):
+        # After stripping, whitespace-only prefix becomes empty, which fails min_length=1
+        # The min_length check happens before the normalizer can return None
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"prefix": "   "})
+
+    def test_prefix_min_length(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"prefix": ""})
+
+    def test_prefix_max_length(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"prefix": "x" * 257})
+
+    def test_limit_bounds_min(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"limit": 0})
+
+    def test_limit_bounds_max(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"limit": 1001})
+
+    def test_limit_bounds_valid(self):
+        q = TagsListQuery.model_validate({"limit": 1000})
+        assert q.limit == 1000
+
+    def test_offset_bounds_min(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"offset": -1})
+
+    def test_offset_bounds_max(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"offset": 10_000_001})
+
+    def test_order_valid_values(self):
+        for order_val in ["count_desc", "name_asc"]:
+            q = TagsListQuery.model_validate({"order": order_val})
+            assert q.order == order_val
+
+    def test_order_invalid(self):
+        with pytest.raises(ValidationError):
+            TagsListQuery.model_validate({"order": "invalid"})
+
+    def test_include_zero_bool(self):
+        q = TagsListQuery.model_validate({"include_zero": False})
+        assert q.include_zero is False
+
+
+class TestScheduleAssetScanBody:
+    def test_valid_roots(self):
+        body = ScheduleAssetScanBody.model_validate({"roots": ["models"]})
+        assert body.roots == ["models"]
+
+    def test_multiple_roots(self):
+        body = ScheduleAssetScanBody.model_validate({"roots": ["models", "input", "output"]})
+        assert body.roots == ["models", "input", "output"]
+
+    def test_empty_roots_rejected(self):
+        with pytest.raises(ValidationError):
+            ScheduleAssetScanBody.model_validate({"roots": []})
+
+    def test_invalid_root_rejected(self):
+        with pytest.raises(ValidationError):
+            ScheduleAssetScanBody.model_validate({"roots": ["invalid"]})
+
+    def test_missing_roots_rejected(self):
+        with pytest.raises(ValidationError):
+            ScheduleAssetScanBody.model_validate({})