feat(views): saved-views store and API

Add a saved_views table (page images|library, trimmed 1-100 character
name, whitelisted JSON state of at most 4 KB, position, timestamps)
installed through the same validated-savepoint migration as image
favorites. It is optional in old backups and required in a migrated
restore stage; restore rejects a tampered definition, extra indexes and
any row that would fail write validation.

Routes under /prompt_manager/saved-views: GET lists views by position,
POST {page,name,state} returns 201 {success, view}, PATCH /{id} {name}
renames and DELETE /{id} removes, both 404 for an unknown id. The state
must hold exactly the page's toolbar and Refine-this-view keys (Images:
q, category, sort, source, folder, media, tags; Library: q, category,
sort, tags) with their types and sort/media values; anything else is a
400.

Refs #249

py/api/__init__.py

@@ -25,6 +25,7 @@ from .prompts import PromptRoutesMixin
 from .pairs import PairRoutesMixin
 from .library import LibraryRoutesMixin
 from .vocabulary import VocabularyRoutesMixin
+from .saved_views import SavedViewRoutesMixin
 from .history import HistoryRoutesMixin
 from .images import ImageRoutesMixin
 from .admin import AdminRoutesMixin
@@ -248,6 +249,7 @@ class PromptManagerAPI(
     PairRoutesMixin,
     LibraryRoutesMixin,
     VocabularyRoutesMixin,
+    SavedViewRoutesMixin,
     HistoryRoutesMixin,
     PromptRoutesMixin,
     ImageRoutesMixin,
@@ -432,6 +434,7 @@ class PromptManagerAPI(
         self._register_pair_routes(routes)
         self._register_library_routes(routes)
         self._register_vocabulary_routes(routes)
+        self._register_saved_view_routes(routes)
         self._register_history_routes(routes)
         self._register_prompt_routes(routes)
         self._register_image_routes(routes)

py/api/saved_views.py

@@ -0,0 +1,107 @@
+"""Saved views (D16): list, create, rename and delete named toolbar states.
+
+The page, the name and the whitelisted per-page state are validated here
+(through ``database/saved_views.py``) before anything is written.
+"""
+
+from functools import wraps
+from typing import Callable
+
+from aiohttp import web
+
+try:
+    from ...database.saved_views import encode_state, validate_name
+except ImportError:
+    from database.saved_views import encode_state, validate_name
+
+_CREATE_FIELDS = frozenset({"page", "name", "state"})
+_RENAME_FIELDS = frozenset({"name"})
+_MAX_ID = 2**63 - 1
+
+
+class SavedViewNotFound(LookupError):
+    pass
+
+
+def saved_view_response(handler: Callable) -> Callable:
+    """``{success:false,error}`` with 400, 404 or 500 on every failure."""
+
+    @wraps(handler)
+    async def wrapped(self, request: web.Request) -> web.Response:
+        try:
+            return await handler(self, request)
+        except SavedViewNotFound:
+            return web.json_response(
+                {"success": False, "error": "Saved view not found"}, status=404
+            )
+        except (ValueError, TypeError) as exc:
+            return web.json_response({"success": False, "error": str(exc)}, status=400)
+        except Exception:
+            self.logger.exception("Saved view operation failed")
+            return web.json_response(
+                {"success": False, "error": "Saved view operation failed"}, status=500
+            )
+
+    return wrapped
+
+
+async def _body(request: web.Request, fields: frozenset) -> dict:
+    """A JSON object whose keys are exactly ``fields``."""
+    body = await request.json()
+    if not isinstance(body, dict):
+        raise ValueError("Expected a JSON object")
+    if set(body) != fields:
+        raise ValueError("Request must contain exactly " + ", ".join(sorted(fields)))
+    return body
+
+
+def _view_id(request: web.Request) -> int:
+    raw = request.match_info["view_id"]
+    if not raw.isascii() or not raw.isdigit():
+        raise ValueError("Invalid saved view ID")
+    value = int(raw)
+    if not 1 <= value <= _MAX_ID:
+        raise ValueError("Invalid saved view ID")
+    return value
+
+
+class SavedViewRoutesMixin:
+    def _register_saved_view_routes(self, routes: web.RouteTableDef) -> None:
+        routes.get("/prompt_manager/saved-views")(self.list_saved_views)
+        routes.post("/prompt_manager/saved-views")(self.create_saved_view)
+        routes.patch("/prompt_manager/saved-views/{view_id}")(self.rename_saved_view)
+        routes.delete("/prompt_manager/saved-views/{view_id}")(self.delete_saved_view)
+
+    @saved_view_response
+    async def list_saved_views(self, request: web.Request) -> web.Response:
+        views = await self._run_in_executor(self.db.list_saved_views)
+        return web.json_response({"success": True, "views": views})
+
+    @saved_view_response
+    async def create_saved_view(self, request: web.Request) -> web.Response:
+        body = await _body(request, _CREATE_FIELDS)
+        encode_state(body["page"], body["state"])
+        validate_name(body["name"])
+        view = await self._run_in_executor(
+            self.db.create_saved_view, body["page"], body["name"], body["state"]
+        )
+        return web.json_response({"success": True, "view": view}, status=201)
+
+    @saved_view_response
+    async def rename_saved_view(self, request: web.Request) -> web.Response:
+        view_id = _view_id(request)
+        body = await _body(request, _RENAME_FIELDS)
+        validate_name(body["name"])
+        view = await self._run_in_executor(
+            self.db.rename_saved_view, view_id, body["name"]
+        )
+        if view is None:
+            raise SavedViewNotFound
+        return web.json_response({"success": True, "view": view})
+
+    @saved_view_response
+    async def delete_saved_view(self, request: web.Request) -> web.Response:
+        view_id = _view_id(request)
+        if not await self._run_in_executor(self.db.delete_saved_view, view_id):
+            raise SavedViewNotFound
+        return web.json_response({"success": True, "id": view_id})