feat: editor write path

docs/llm/gotchas.md

@@ -58,8 +58,8 @@ Sleep for `Retry-After` seconds, then retry once. Do not retry in a tight loop.
 
 ## Writes
 
-- A title cannot be changed after creation. Create a new article instead.
-- `PATCH /v1/article/{id}` accepts `body`, `site_id`, `author_ids` and the SEO fields only. `{}` and `null` values answer `400`, except `cover_image_id` and `social_image_id`, where `null` removes the image.
+- A title can be changed with `PATCH /v1/article/{id}` (3 to 200 characters); the slug is not regenerated. Send `if_revision` to refuse overwriting a newer save (`409 revision_conflict`).
+- `PATCH /v1/article/{id}` accepts `title`, `body`, `site_id`, `author_ids`, `if_revision` and the SEO fields only. `{}` and `null` values answer `400`, except `cover_image_id` and `social_image_id`, where `null` removes the image.
 - Request bodies are HTML even though responses default to markdown. Send `<p>` and `<h2>`, not markdown syntax, or it is stored literally.
 - Ids in paths are unsigned integers. Anything else answers `400`.