Speed up test suite across 4 packages (~15s → ~6s)

[cpcloud]

Summary

• Isolate agent, config, and review tests from global git config — extends Isolate tests from global git config to prevent gpg-agent/pinentry #531 to three more packages. Adds TestMain calling testenv.RunIsolatedMain() so git operations in tests never trigger the host's gpg-agent/pinentry (which can add 1-2s per invocation on machines with GPG signing configured).

• Make worker pool idle sleeps responsive to shutdown — replaces time.Sleep in the worker idle loop with a select on a shutdown channel, so tests that stop the daemon don't block waiting for the sleep to finish.

• Stub isPROpenFn in CI poller test harness — avoids shelling out to gh CLI during tests. Removes a source of ~0.5s latency and flaky failures when gh isn't authenticated.

• Parallelize daemon subtests — marks 21 independent daemon tests as t.Parallel(), including TestIsDaemonAliveLegacyStatusCodes subtests and the bulk of the worker/failover/cancellation tests. Drops internal/daemon from ~7.2s to ~4.2s.

• Tighten requireNever timeout — the invalid-config watcher test was waiting 500ms for a "never" assertion; 100ms is sufficient and shaves ~400ms.

• Fix configureSubprocess to always set Cancel on exec.Cmd — when called on a plain exec.Command (no context), cmd.Cancel is nil, so the wrapper's cancel() call panicked. Now sets a default Kill cancel before wrapping. This is a correctness fix surfaced by the timing changes below.

• Speed up agent subprocess tests (8s → 1s) — two changes:

  1. Override subprocessWaitDelay from 5s to 50ms in tests that don't need the production grace period.
  2. Add a Go 1.25 ETXTBSY probe guard (case "$1" in *etxtbsy*) exit 0;; esac) to shell-script test fixtures.

Go 1.25 ETXTBSY probe — why the guard is necessary

Go 1.25 added a built-in ETXTBSY probe to os/exec: every Cmd.Start() call forks a child that runs execve(path, [path, "--help-probe-etxtbsy"]). If execve succeeds (file isn't busy), the probe child actually executes the script — it isn't killed, and the parent waits for it to exit before proceeding.

For shell scripts, this means the script runs twice: once as the probe (with $1 = "--help-probe-etxtbsy"), and once as the real invocation. If the script ignores $1 and does something slow (like sleep 5), the probe child runs the full body, and Go waits for it — adding the script's entire runtime as invisible overhead to Cmd.Start().

This was confirmed via strace -f: two child PIDs ran the same clock_nanosleep(5s), one from the probe fork (CLONE_VFORK|CLONE_PIDFD) and one from the real execution. The probe child was waited on via waitid(P_PIDFD).

The guard pattern — case "$1" in *etxtbsy*) exit 0;; esac as the first line after the shebang — makes the probe child exit immediately. This is only needed in test fixtures; real agent binaries already handle unknown flags gracefully.

Further details are documented in internal/agent/agent_test_helpers.go on the writeTempCommand function.

🤖 Generated with Claude Code

[roborev-ci]

roborev: Combined Review (6661736)

Summary: This PR improves test isolation and runtime, optimizes subprocess cancellation logic, and makes worker idle sleeps responsive to shutdown.

All reviewers agree the code is clean with no issues of medium or
higher severity found.

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Synthesized from 3 reviews (agents: codex, gemini | types: default, security)

[cpcloud]

The fact that this exists is super weird to me. Many scripts ignore their arguments, so now it seems that in Go 1.25 those scripts always execute twice unless users explicitly handle this one weird, go-specific flag.

[wesm]

Good deal. thanks for doing this!