feat(library): add tags to many selected prompts and select every loaded prompt (#442)

The Library selection bar (D148) gets Add tags and select-all of the loaded
shelf, the legacy admin page's bulk Add Tags and select-all checkbox.

Add tags posts {prompt_ids, tags, expected_epoch} to
POST /prompt_manager/bulk/tags: in one BEGIN IMMEDIATE transaction the server
checks the storage epoch, normalizes the names as image tags are, gives each
Library parent only the names it lacks (casefold), finds or inserts tag rows
by exact name only when some prompt gets them, and skips prompts that would
pass 20 tags. Prompt tags only. Both bulk/tags forms refuse a non-object body
with 400.

Ctrl/Cmd+A in the grid and "Select all N loaded" in the bar select every
loaded prompt; the offer follows each loaded batch.

Closes #442

py/api/prompts.py

@@ -1130,7 +1130,14 @@ class PromptRoutesMixin:
     async def bulk_add_tags(self, request):
         """Bulk add tags to prompts."""
         try:
-            data = await request.json()
+            try:
+                data = await request.json()
+            except ValueError:
+                return bad_request("Invalid JSON body")
+            if not isinstance(data, dict):
+                return bad_request("Expected a JSON object")
+            if "expected_epoch" in data:
+                return await self._bulk_library_tags(data)
             prompt_ids = data.get("prompt_ids", [])
             new_tags = data.get("tags", [])
 
@@ -1220,14 +1227,20 @@ class PromptRoutesMixin:
                 status=500,
             )
 
-    async def _bulk_library_category(self, data: dict) -> web.Response:
-        """The workspace Library's fenced form (#437).
+    async def _bulk_library_tags(self, data: dict) -> web.Response:
+        """The workspace Library's fenced form (#442).
 
-        ``{prompt_ids, category, expected_epoch}``: a non-blank category on
-        the selected Library parents, refused with 409 ``storage-changed``
-        when prompt storage was restored since the page read its epoch.
+        ``{prompt_ids, tags, expected_epoch}``: prompt tags only, never image tags.
         """
-        fields = {"prompt_ids", "category", "expected_epoch"}
+        return await self._fenced_library_write(
+            data, "tags", self.db.bulk_add_library_tags
+        )
+
+    async def _fenced_library_write(
+        self, data: dict, field: str, write
+    ) -> web.Response:
+        """One fenced Library bulk write: exact keys, checked ids, 409 on a restore."""
+        fields = {"prompt_ids", field, "expected_epoch"}
         if set(data) != fields:
             return bad_request(
                 "Request must contain exactly " + ", ".join(sorted(fields))
@@ -1235,10 +1248,7 @@ class PromptRoutesMixin:
         try:
             prompt_ids = parse_bulk_prompt_ids(data["prompt_ids"])
             result = await self._run_in_executor(
-                self.db.bulk_set_library_category,
-                prompt_ids,
-                data["category"],
-                expected_epoch=data["expected_epoch"],
+                write, prompt_ids, data[field], expected_epoch=data["expected_epoch"]
             )
         except LibraryCommandError as exc:
             return web.json_response(
@@ -1254,6 +1264,17 @@ class PromptRoutesMixin:
             return bad_request(str(exc))
         return web.json_response({"success": True, **result})
 
+    async def _bulk_library_category(self, data: dict) -> web.Response:
+        """The workspace Library's fenced form (#437).
+
+        ``{prompt_ids, category, expected_epoch}``: a non-blank category on
+        the selected Library parents, refused with 409 ``storage-changed``
+        when prompt storage was restored since the page read its epoch.
+        """
+        return await self._fenced_library_write(
+            data, "category", self.db.bulk_set_library_category
+        )
+
     async def _bulk_category_by_filter(self, data: dict) -> web.Response:
         """Set the category on every linked positive a listing filter admits.