perf(images): cache the removal marks so a listing page reads no extra table (#480)

The marks reload only when this process writes or clears one, or a restore
replaces the database. The route snapshot gains the preview route.

database/image_removal_schema.py

@@ -140,6 +140,21 @@ BUMP_MARKS_SQL = (
 )
 
 
+# Bumped whenever this process writes or clears a mark (even in a transaction
+# that later rolls back): readers that cache the marks reload when it moves.
+_generation = 0
+
+
+def generation() -> int:
+    """The marks generation of this process (see ``_generation``)."""
+    return _generation
+
+
+def _bump() -> None:
+    global _generation
+    _generation += 1
+
+
 def has_marks_table(conn: sqlite3.Connection) -> bool:
     return (
         conn.execute(
@@ -167,6 +182,7 @@ def write_mark(
 ):
     conn.execute(_MARK_SQL, (locator, int(size), int(mtime_ns), now))
     conn.execute(BUMP_MARKS_SQL)
+    _bump()
 
 
 def clear_marks(conn: sqlite3.Connection, locators) -> int:
@@ -183,6 +199,7 @@ def clear_marks(conn: sqlite3.Connection, locators) -> int:
         removed += conn.execute(_UNMARK_SQL, (locator,)).rowcount
     if removed:
         conn.execute(BUMP_MARKS_SQL)
+        _bump()
     return removed
 
 

py/api/__init__.py

@@ -425,6 +425,12 @@ class PromptManagerAPI(
         # Reviewed maintenance plans under single-use tokens; a restart
         # forgets them (py/api/maintenance.py).
         self._maintenance_plans = PlanStore()
+        # #480: the removal marks the workspace listing hides, read once now so
+        # a listing page reads no table until a mark or the database changes.
+        try:
+            self._removal_marks()
+        except Exception:
+            self.logger.warning("Removal marks could not be read", exc_info=True)
 
         # A safety backup interrupted by a crash leaves its temp copy behind.
         try:

py/api/admin.py

@@ -884,7 +884,7 @@ class AdminRoutesMixin:
         media_files = []
         seen = set()
         # #480: a file removed from the library is never a copy or a keeper.
-        marks = self.db.removal_marks()
+        marks = self._removal_marks()
         for slot, root in enumerate(roots):
             for path in _collect_media_files([root], extensions):
                 try:

py/api/image_delete.py

@@ -46,9 +46,11 @@ from .job_routes import busy_response
 from .maintenance import MAINTENANCE_PREVIEW_LEASE, _fail_job, _failure, backup_note
 
 try:
+    from ...database import image_removal_schema
     from ...database.annotation_schema import MAX_LOCATOR_LENGTH
     from ...utils import trash
 except ImportError:
+    from database import image_removal_schema
     from database.annotation_schema import MAX_LOCATOR_LENGTH
     from utils import trash
 
@@ -417,6 +419,19 @@ class ImageDeleteMixin:
 
     # ── the workspace listing ─────────────────────────────────────────
 
+    def _removal_marks(self) -> dict:
+        """The removal marks, cached until a mark changes or the database does.
+
+        A listing page reads no table while nothing changed: the cache follows
+        this process's marks generation and the database identity (a restore).
+        """
+        key = (self._database_identity(self.db), image_removal_schema.generation())
+        cached = getattr(self, "_marks_cache", None)
+        if cached is None or cached[0] != key:
+            cached = (key, self.db.removal_marks())
+            self._marks_cache = cached
+        return cached[1]
+
     def _hidden_entries(self, listings) -> set:
         """Normalized paths of listed files a removal mark hides (blocking).
 
@@ -424,7 +439,7 @@ class ImageDeleteMixin:
         ``lstat``'ed: a mark hides a file while its size and ``mtime_ns`` are
         still the ones it was removed with.
         """
-        marks = self.db.removal_marks()
+        marks = self._removal_marks()
         if not marks:
             return set()
         located = self._workspace_locators(listings)
@@ -443,7 +458,7 @@ class ImageDeleteMixin:
 
     def _removed_paths(self, paths) -> set:
         """The absolute paths among *paths* a removal mark hides (blocking)."""
-        marks = self.db.removal_marks()
+        marks = self._removal_marks()
         if not marks:
             return set()
         hidden = set()

tests/fixtures/legacy_contract_snapshot.json

@@ -118,6 +118,7 @@
     "POST /prompt_manager/image-annotations/observe",
     "POST /prompt_manager/image-annotations/suggest",
     "POST /prompt_manager/images/clear-thumbnails",
+    "POST /prompt_manager/images/delete/preview",
     "POST /prompt_manager/images/generate-thumbnails",
     "POST /prompt_manager/images/generate-thumbnails/progress",
     "POST /prompt_manager/images/link",