PR: https://git.cafe/pingdotgg/t3code/pulls/33290
main: 61cb845d9699d0ecce5a9b660d3b32907914df8b
PR head: 65bc2580b7a709a1f8b14b18d4d8cb2d639fb355
Linux, Google Chrome, repo Playwright, real Codex v0.167.0, gpt-6.1-sol via local proxy.

Created startup-diagnostics git project through the web app. Sent actual provider turns.
Main: vp i; background vp run dev (isolated /home/user/main/.t3).
Ports read from dev-runner: server 16733, web 8693.
Stopped captured main process group before starting PR.
PR: exact detached head; vp i; background vp run dev --home-dir /home/user/t3code/.t3.
Ports read from dev-runner: server 13773, web 5733.

Failure launcher configured through Settings > Providers > Codex > Binary path:
#!/bin/sh
if [ "$1" = "app-server" ]; then
  sleep 1
  /usr/local/bin/codex "$@" -c =broken
  status=$?
  if [ "$status" -ne 0 ]; then
    printf 'Error: provider launcher exited with code %s.\n' "$status" >&2
  fi
  exit "$status"
fi
exec /usr/local/bin/codex "$@"

Actual child stderr:
Error: error parsing -c overrides: Empty key in override: =broken
Error: provider launcher exited with code 1.

Main Settings status / chat provider warning / server error:
Codex App Server process exited with code 1: Error: provider launcher exited with code 1.

PR Settings status / chat provider warning / server error:
Codex App Server process exited with code 1: Error: error parsing -c overrides: Empty key in override: =broken | Error: provider launcher exited with code 1.

Cold PR server startup + new thread: session fails, real error chain retains both lines.
Plain-error neighboring check: same actual Codex configuration failure, no appended summary.
UI preserves Error: error parsing -c overrides: Empty key in override: =broken.
Recovery: restored /usr/local/bin/codex through settings; refreshed status => Available.
New gpt-6.1-sol turn without restart => startup verification recovered.
Healthy gpt-6.1-sol turns also completed on main and PR before failure.

Blacksmith: vp test run packages/effect-codex-app-server/src/_internal/stdio.test.ts => 19 passed.
Blacksmith: vp run check:changed 402d0623d5f4160859607e9b7c11fc829fbe3e18 => all steps pass.
format, lint, knip 1/2 and 2/2, typecheck (4 packages), test (2 files / 21 tests).
Worker required explicit PR ancestry fetch because initial source snapshot is shallow.
Existing CI: 29 successful, 0 failing, 0 pending.

Limit: without the launcher startup delay an immediate exit can race the initialize write,
showing a generic transport write-output-stream error on main. This change does not address that race.
No synthetic diagnostics, mock provider, fixtures, replay turns, or repository source edits.
Native desktop/mobile, other operating systems, remote relay/tunnel, and actual gateway DNS/OAuth outages not exercised.