Claude Code: serve and delegate A2A tasks

[dimavrem22]

Decisions

• Live protocol coverage: Exercise inbound and outbound behavior at both single-turn and multi-turn lengths. Serialize the four cases because they share live identities and one tunnel endpoint.
• Durability: Write receiver deliveries before acknowledgement and reconcile registry state before paging every submitted task on restart.
• Session isolation: Serialize inbound work in a2a:{identity}:{context} sessions and expose complete, ask-caller, and fail only through verified turn context.
• Delegation continuity: Persist outbound message and retry data before SendMessage, promote it to (identity, RPC origin, context) after submission, and inject later task updates into the originating Claude session.
• Compatibility: Keep the base SDK range for non-A2A users, while requiring Inkbox SDK 0.5.6 or newer for A2A.

Changes

• Add a published-SDK live A2A workflow that boots the real host and verifies all four protocol legs.
• Add A2A call, check/wait, reply, and explicit inbound outcome tools.
• Subscribe and serve inbound A2A tasks with durable deduplication, context sessions, cancellation, restart recovery, and guarded default completion.
• Persist caller-side delegation routing and return a2a.sent_task.updated events to the delegating session.
• Bump the plugin to 0.1.4.

Related pull requests

• SDK: Inkbox PR #123
• Hosts: Hermes PR #75, Codex PR #26, OpenCode PR #9, OpenClaw PR #43

Verification

• Tests: Python 3.11 and 3.12 unit suites and the Claude Code host contract passed.
• Full stack e2e: mock and real channel suites, inbound and outbound A2A at single-turn and multi-turn lengths, both voice scenarios, external events, and the aggregate gate passed.
• uv run --with pytest python -m pytest -q: 303 passed, 22 skipped.