Follow-up to #30511 — the after_tool_call hook context was passing
`agentId: undefined` because SubscribeEmbeddedPiSessionParams did not
carry the agent identity. This threads sessionAgentId (resolved in
attempt.ts) through the session params into the tool handler context,
giving plugins accurate agent-scoped context for both before_tool_call
and after_tool_call hooks.
Changes:
- Add `agentId?: string` to SubscribeEmbeddedPiSessionParams
- Add "agentId" to ToolHandlerParams Pick type
- Pass `agentId: sessionAgentId` at the subscribeEmbeddedPiSession()
call site in attempt.ts
- Wire ctx.params.agentId into the after_tool_call hook context
- Update tests to assert agentId propagation
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>