Once a user creates a Pattern in the Canvas editor, there is no way to edit it. The library menu for a pattern offers only Insert and Delete — there is no "Edit", "Open", or "Rename". If a pattern was created with a mistake, or needs to evolve, the only option is to delete it and recreate it from scratch. This is surprising because the backend already fully supports updating a pattern — the gap is entirely on the client, plus one missing architectural piece (a round-trip to load a pattern back into the editor). - Backend UPDATE already works. Pattern is a config entity storing a component_tree snapshot (src/Entity/Pattern.php), and it implements updateFromClientSide() (Pattern.php:154). A working PATCH /canvas/api/v0/config/pattern/{id} endpoint exists (ApiConfigControllers.php:331; route canvas.api.config.patch explicitly allows pattern at canvas.routing.yml:211). - Frontend exposes create + delete only. ui/src/services/patterns.ts defines savePattern (POST) and deletePattern (DELETE) but no update mutation. PatternItem.tsx:40-55 shows only Insert/Delete. There is no edit dialog (PatternDialogs.tsx) and no edit/rename op in dialogSlice.ts. - No round-trip to edit a pattern in-canvas. The editor only ever edits a content entity (canvas_page) via the layout/model + auto-save machinery, and patterns are explicitly excluded from auto-save (canvas.routing.yml:57-59, 117-119). At insert time a pattern is deep-copied into the page with brand-new UUIDs (replaceUUIDsAndUpdateModel, ui/src/features/layout/layoutUtils.ts:477/493), so inserted instances hold no reference back to the source pattern.