[gwdp]

Why

A Stop request that arrives while an Argent session is still starting does not end startup. The worker goes on through Simulator preparation, the Argent setup commands and the tool-server start, and then reports the session as ready. #4666 fixes this for agent-device. This PR does the same for Argent.

How

• Use the shared startup Stop watch from [build-tools] Stop agent-device startup when the session is stopped #4666 (watchDeviceRunSessionStartup), with a createStartupTasks startup signal, like agent-device.
• Pass the startup signal to Simulator preparation, the host start, every Argent setup command, the tool-server state wait and the ready report. On Stop, the pending work is cancelled, and the step ends without a ready report.
• The prepared-iOS setup commands are now cancellable on all platforms, not only when this step boots the Simulator.
• End the watch after the ready report and before the lifetime wait, so only one status poll runs at a time.
• A Stop during startup ends the step without an error. Any other failure keeps its first error, and teardown errors stay visible.
• Artifact polling is unchanged.

Test Plan

• New controller tests: Stop during setup on macOS and Linux, a teardown failure after Stop that stays visible, and cancellable prepared setup commands.
• Claude Code ran the build-tools typecheck and the src/steps tests on this commit (1946 passed, 8 skipped), and the root build, typecheck, oxlint, oxfmt and Lerna tests on the top of the stack (2511 passed, 8 skipped).
• CI passes on 9a8519f. Codecov reports all changed lines covered.
• Planned: a hosted check that Stop during Argent startup ends the session without a ready report.

Authorship and LLM use

Gabe asked for Stop coverage for every Simulator session type, with one PR per type. Codex wrote the first version, which added the startup watch in this PR, and Devin found no issues in that version. Claude Code rebased it onto the current #4666. On Gabe's request, Claude Code moved the watch into #4666 and gave the three session types the same startup code. Gabe reviewed the final diffs and can answer questions.

Generated with T3 Code, using Claude Code.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.39%. Comparing base (bf60bca) to head (9a8519f).

Additional details and impacted files

@@                             Coverage Diff                             @@
##           gwdp/agent-device-startup-stop-20261016    #4667      +/-   ##
===========================================================================
+ Coverage                                    75.38%   75.39%   +0.01%     
===========================================================================
  Files                                         1055     1056       +1     
  Lines                                        52359    52370      +11     
  Branches                                     11390    11387       -3     
===========================================================================
+ Hits                                         39466    39477      +11     
  Misses                                       11904    11904              
  Partials                                       989      989              

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[github-actions]

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