fix(integration-tests): honor stdinDoesNotEnd option

[chinesepowered]

Fix stdinDoesNotEnd test option being completely non-functional.

TLDR

integration-tests/test-helper.ts had a conditional child.stdin.end() scoped to object-type promptOrOptions, followed immediately by an unconditional child.stdin.end(). The unconditional call always ran, so { stdinDoesNotEnd: true } had no effect — any integration test that tried to keep stdin open for streaming input had it closed anyway. This PR restructures the check so stdin stays open exactly when stdinDoesNotEnd: true was explicitly requested.

Screenshots / Video Demo

N/A — test-infrastructure fix, no user-visible UI.

Dive Deeper

TestRig.run() accepts promptOrOptions: string | { prompt?; stdin?; stdinDoesNotEnd? }. The broken code was:

// Before
if (
  typeof promptOrOptions === 'object' &&
  !promptOrOptions.stdinDoesNotEnd
) {
  child.stdin!.end();   // conditional — honored the flag
}
child.stdin!.end();     // unconditional — defeated the flag

Simply deleting the unconditional line would have broken the string-prompt path — when the caller passes rig.run('say hi') the typeof 'object' guard is false, the conditional skips, and the stray unconditional call was actually the catch-all that closed stdin for string callers. Removing it without restructuring the guard would cause every string-prompt test to hang waiting for EOF.

The correct fix inverts the logic: default to closing stdin, and only keep it open when stdinDoesNotEnd: true is explicitly passed on an options object.

// After
const keepStdinOpen =
  typeof promptOrOptions === 'object' &&
  promptOrOptions !== null &&
  promptOrOptions.stdinDoesNotEnd === true;
if (!keepStdinOpen) {
  child.stdin!.end();
}

Coverage of all call patterns:

Call	keepStdinOpen	stdin.end() called?
run('say hi') (string)	false	✅
run({ prompt: 'hi' })	false	✅
run({ stdinDoesNotEnd: true })	true	❌ (as intended)
run({ stdinDoesNotEnd: false })	false	✅
run(null) (null is typeof 'object')	false	✅

The explicit !== null guard covers the JavaScript quirk that typeof null === 'object' — otherwise the first clause would pass and we'd dereference .stdinDoesNotEnd on null.

Modified file:

• integration-tests/test-helper.ts — restructured stdin-close logic

Reviewer Test Plan

1. Existing string-prompt tests (the most common case) should still close stdin normally — no regressions
2. Existing object-prompt tests without stdinDoesNotEnd should still close stdin normally
3. Any test passing stdinDoesNotEnd: true should now actually keep stdin open — this path was previously dead code
4. grep -n "stdin!.end" integration-tests/test-helper.ts — should show a single call inside the if (!keepStdinOpen) block

Testing Matrix

	macOS	Windows	Linux
npm run	?	pass	?
npx	?	?	?
Docker	?	?	?
Podman	?	-	-
Seatbelt	?	-	-