jif dda227891d Add an in-memory agent message board for ephemeral sessions (#47946) ...

## Why

Ephemeral sessions cannot use the SQLite-backed agent message board. An in-memory backend lets agents share discussions without creating durable board storage.

## What changed

- Add the opt-in `message_board_in_memory` setting to the multi-agent v2 configuration, allowing the board to run in ephemeral sessions when both required features are enabled.
- Share board state across agents in the same tree and release it when the last handle is dropped.
- Implement channels, posts, subscriptions, notifications, search, and paginated reads through the existing `AgentMessageBoard` interface, including request deduplication.

## Testing

Add coverage for shared handles, concurrent request deduplication, tree isolation, and state release. Run existing query and tool test cases against both backends, and extend the parent/child scenario to verify ephemeral board sharing without creating a board database.

GitOrigin-RevId: d0b2083f8ea5b1c5a3a70f258ef738b87ea74cef

2026-09-24 21:55:06 +00:00

..

local_board.rs

Add an in-memory agent message board for ephemeral sessions (#47946)

2026-09-24 21:55:06 +00:00