Collaboration and channels

Four collaboration objects

Object	Use it for	Lifetime and authority
Role	Reusable responsibility, model, and instructions	Definition, not an execution identity
Session	Continuing conversation, execution identity, and mailbox	Durable and daemon-owned
Side Thread	Read-only tangent attached to one parent session	Child session with explicit handoff
Channel	Feishu, Infoflow, or QQ Bot conversation	Adapter bound to a daemon session

Choose a Role when the responsibility should be reusable. Choose a Session when work needs an independent history, queue, or durable identity. Use a Side Thread for a bounded read-only tangent.

Session requests and notifications

Sessions can send another local session:

• a request, which queues the exact body as work; or
• a notification, which records information without starting work.

The default accepted wait confirms admission, not completion. A completed wait can return a bounded terminal result. Timeouts stop the sender’s wait, not the target execution. Completion summaries return to the originating session so it can continue without polling.

The session agent tool, TUI /inbox, and spark daemon session inbox perform list/read/ack through daemon RPCs. Frontends and extension hosts do not open another session’s mailbox files directly.

Message-platform channels

Channel adapters normalize an inbound platform message, bind it to a workspace session, and submit it through the daemon. They do not own task, session, or execution truth. Outbound delivery fails closed when a provider response is ambiguous, avoiding an automatic duplicate send.

For a smaller remote attack surface, a channel-bound agent receives only four canonical tools:

• session sends requests or notifications to another session.
• ask pauses for structured user input.
• context previews bounded registered context providers.
• todo tracks the current session’s checklist.

Shell execution, role fan-out, assignment, and workflow execution remain disabled on that surface.

ACP clients

spark acp is a stdio adapter for compatible editor clients. It uses canonical daemon sessions for text prompts, cancellation, streamed updates, and tool permission. It is an adapter, not another session store or executor.