[Pepps233]

Summary

Mixed tool batches containing update_plan or another sequential tool currently serialize every call.

Execute consecutive parallel-capable calls concurrently while keeping sequential tools as exclusive barriers in assistant source order.

For example, read A, read B, update_plan, read C, read D runs as [A + B], then update_plan, then [C + D].

Reasoning

Reuse the existing executors and executionMode metadata to preserve tool lifecycle behavior without introducing another scheduling mode or configuration flag.

Each phase settles execution, result hooks, completion events, and ordered result-message events before the next phase starts preflight.

The model selects independent calls; file dependencies and shell side effects are not inferred.

Changes

• Partition globally parallel batches into consecutive parallel groups and individual sequential barriers.
• Preserve global sequential execution, source-ordered transcript results, batch-wide termination, cancellation, and batch-boundary steering delivery.
• Add promise-gated agent tests and a faux-provider session reproduction using the real persisted update_plan tool.
• Document barrier behavior, event ordering, and hook visibility in API comments, the agent README, and extension documentation.
• Correct two stale summary expectations from main to include persisted plan context, in a separate test-only commit.

Testing

• Reproduced the original serialization failure through the session harness before implementation.
• Package-scoped Vitest: 97 agent tests and 70 session, plan, event-settlement, compaction, and user-input tests passed.
• npm run check passed.
• ./test.sh passed with credentials isolated; localhost fixture servers required running outside the filesystem/network sandbox.