## Why
Guardian's retrieval, channel selection, and evidence delivery depend on concrete local message-board types. Expose the required operations through shared interfaces so these consumers can use trait-based board handles.
## What changed
- Introduce `BoardReadView` for captured catalogs and post boundaries, with read operations and JSON search configuration but no mutation methods.
- Extend `AgentMessageBoard` with namespace identification, read-view capture, and channel subscription operations, and implement them for the local board.
- Add `message_board_read_tools` to bind the five read-only tools to a captured view.
- Migrate Guardian consumers to `AgentMessageBoard` and `BoardReadView`, retaining Guardian namespace checks and captured read boundaries.
## Testing
Adapt read-view and Guardian retrieval tests to the trait interfaces. Add assertions for the five retrieval tools and rejection of ordinary boards by retrieval binding, subscription capture, and delivery planning.
GitOrigin-RevId: f8c5bc65d8297f6df6e3b02d6c09006bcaea4b1a
Document that `AgentMessageBoard` notification delivery follows the host's
scheduling and wake policy and may buffer notifications for idle recipients.
Link to `MessageBoardHost` for the delivery contract.
GitOrigin-RevId: fb085fe2c43c74b85b4e6fe471e7d4ae216bf3db
## What changed
Add an `upsert_channel` API and selectable tool to create a channel or replace only its description. Local and in-memory boards preserve existing posts, authorship, creation time, and subscriptions without sending notifications. Updating an existing channel does not require the host clock.
Require write access for local boards and reject upserts on remote boards, whose service lacks description updates.
## Testing
Add coverage for both local and in-memory upserts, argument validation, mutation budgets, metadata preservation, and clock failures. Verify read-only local boards reject updates and remote boards reject upserts without sending requests.
GitOrigin-RevId: e667375a62784f2fbeeff72359b5b0fa476e061e
## Why
Recording evidence on a message board needs a write operation that does not automatically subscribe the author or notify existing subscribers.
## What changed
- Add `AppendRequest` and `AgentMessageBoard::append` for local and in-memory boards, supporting new channels, existing channels, and thread replies without subscription or notification side effects.
- Expose an explicitly selected `append` tool that accepts a destination and text, with no notification recipients.
- Share caller-scoped request IDs with `post`: identical retries return the original metadata, while changes to the payload or operation are rejected. Local appends retain write permission checks and durable storage.
- Reject remote appends as unsupported without issuing an HTTP request.
## Testing
Add coverage for silent writes on both supported backends, tool argument validation and retry conflicts, local read-only access and retries after reopening storage, and remote rejection without network requests.
GitOrigin-RevId: 01fb9d3e2cfcb3de362b28f2bf2ee83bafada80d
## What changed
Move the message-board API, types, permissions, storage backends, and tool implementations into the new `codex-message-board` crate. Keep extension registration in `codex-agent-message-board-extension`, and update core and the remote client to use the shared crate directly.
Move the existing board tests with the implementation and add the crate to the Cargo workspace and Bazel build.
GitOrigin-RevId: 33ce527c2bef7f862eba55cb9b32222902ccf4ad
felixxia-oai