PR 18385 runtime verification, Linux Boat VM
main: 575579d68a (github/main)
PR original head: 91f9d97ff0b75534380bcbe6aaa7004a075844b3
fix: ce5c2c1d5f

Setup: timeout 600 vp i; background vp run dev with isolated task state.
One dev server at a time: main server=16733 web=8693, stopped before PR server=13773 web=5733.
Chrome: /usr/bin/google-chrome; Playwright 1.60.0 from repository dependencies.
Created real project /home/user/t3code and two threads through web UI.
Both threads completed Codex gpt-6.1-sol turns (RECEIPT-A-OK / RECEIPT-B-OK), without mocks.

Authenticated WebSocket /ws?orchestrationProtocol=2, public orchestration.dispatchCommand.
Two concurrent thread.model-selection.set requests: unique RPC ids, same commandId, distinct threadIds, low -> high reasoning.
main: Success(sequence=86) / Success(sequence=86)
main persisted options: high / low
PR with fix: Success(sequence=121) / Failure(OrchestratorCommandIdConflictError)
PR persisted options: high / low

Two concurrent thread.guest-share.close requests, no share exists:
Original PR: Success(sequence=113) / Success(sequence=114)
Fixed PR: Success(sequence=121) / Failure(OrchestratorCommandIdConflictError)

Nearby behavior:
Winning model command same-thread replay: Success, original sequence 121; entire projection unchanged=true.
Cross-thread sequential replay: Failure, command-id conflict.
No-op same-thread replay: Success, original sequence 121.
Distinct command ids, model-selection writes: Success / Success.
Distinct command ids, no-share closes: Success / Success.
UI changed reasoning to High and real Codex follow-up returned RECEIPT-FOLLOWUP-OK; persisted after browser reload.

Checks on Blacksmith: focused receipt/intake/guest-share tests 13 passed.
vp run check:changed e5909e53c32a9d5b51caf6352d1f17fd73e86db7: format, lint, both knip passes, graphql, affected typechecks, 17 tests passed.
The explicit base ref was needed because the worker snapshot has shallow history.

Not exercised: native desktop/mobile clients, other providers, relay/tunnel, queue-resume collision side effects.