PR b8972cceb696: desktop sign-in created real callback listener 127.0.0.1:49867
after Cancel: desktop callback listener count=0
exact callback port 49867 successfully rebound after cancellation
retry through UI created real desktop callback listener 127.0.0.1:53410
after second Cancel: desktop callback listener count=0
Pending browser-launch race NOT reproduced: on Linux Electron openExternal resolves before the OS browser processes the request.

baseline github/main 61c3794c32b0eeebfac09add43e403618c65d2d7:
real Linux desktop Codex sign-in created callback listener 127.0.0.1:60553.
cancel through onboarding closed that listener.
with an owned system Chrome process suspended, ElectronShell.openExternal still completed in 2.8513 ms; the pending-launch precondition was not established.

PR web client, real Codex gpt-6.1-sol through local proxy:
app-created project: /home/user/callback-verification (real git repository).
first turn response: CALLBACK_BASELINE_OK.
Stop generation interrupted a real sleep 90 tool call; client displayed Run interrupted / Stopped by user.
next turn response: CALLBACK_RECOVERY_OK.

Blacksmith commands reproduced this turn:
vp run build:desktop: 5/5 tasks passed on main and PR (libsecret-1-dev installed on workers).
vp test run apps/desktop/src/app/CodexAuthCallback.test.ts: 1 file passed, 4 tests passed on PR.
existing callback tests use browser mocks and do not establish real pending-browser-launch verification.
no source changes, commits, or pushes.