Add PUT /sessions/{session_id}/messages/{index} to edit a user message and prune all subsequent messages.
Add POST /sessions/{session_id}/regenerate to regenerate an assistant response from a given index (supports optional streaming).
Introduce EditMessageRequest and RegenerateRequest schemas.
Update the frontend to: • allow in‑place editing of user messages with an auto‑focusing textarea; • copy messages to clipboard; • regenerate assistant responses via a button.
Add new CSS rules for message options bars and the editing textarea.
Victor Giers
08d27f0007