## Why
Clients need to refresh section membership and ordering when another client moves a thread.
## What changed
Broadcast `thread/section/changed` after a successful `thread/section/move`, including moves within the same section. Send the response before the notification, and include `threadId` and the destination `sectionId`, using `null` for removal. Failed moves do not emit the notification.
Add the notification to the protocol schemas, TypeScript exports, and Python SDK models and registry, and document its behavior.
## Testing
Add a WebSocket integration test with separate writer and observer clients covering section insertion, reordering, removal, and a failed move.
GitOrigin-RevId: 128ba7eddc9aae8e3bac766f47e4a2c55c64a6a5
## What changed
- Add optional `icon` and `color` appearance fields to custom thread sections and expose them through the app-server protocol.
- Persist appearance metadata in SQLite and include it when listing sections or returning threads.
- Let `threadSection/update` preserve an omitted appearance, clear it with `null`, or replace it with a new value.
- Reject appearance fields larger than 64 bytes.
## Testing
- Cover protocol compatibility, persistence across restart, update and clear behavior, and field-length validation.
GitOrigin-RevId: 8f55ce4f42f8bd17aa5416848a85845f681953df
## What changed
- Add `threadSection/create`, `threadSection/update`, and `threadSection/delete` app-server methods, with generated protocol schemas and TypeScript bindings.
- Persist custom sections in SQLite with stable UUIDv7 identities, trim and validate display names, and prevent renaming or deleting the built-in pinned section.
- Delete sections transactionally and return their active and archived threads to the unsectioned list.
- Serialize section mutations with section listing so concurrent requests observe ordered updates.
## Testing
- Cover section persistence across restarts, ordered renames, member cleanup on deletion, invalid requests, unsupported stores, and thread-store/state-runtime behavior.
GitOrigin-RevId: dc9a4be283c21dbc93ab1829eafc4825d8df6575
Charlie Marsh