fix(runtime): contain and clean temporary workspaces

scripts/run-tests.test.mjs

@@ -1,7 +1,16 @@
 import assert from 'node:assert/strict'
+import { existsSync, writeFileSync } from 'node:fs'
+import { spawnSync } from 'node:child_process'
 import test from 'node:test'
 
-import { buildNodeTestArgs, checkSupportedNodeVersion, filterDefaultTestFiles } from './run-tests.mjs'
+import {
+  buildNodeTestArgs,
+  buildTestEnvironment,
+  checkSupportedNodeVersion,
+  filterDefaultTestFiles,
+  withTestRunTempRoot,
+} from './run-tests.mjs'
+import { CHATLAB_TEMP_ROOT_ENV } from './chatlab-temp.mjs'
 
 test('default test collection excludes e2e, smoke, and real external tests', () => {
   const files = [
@@ -39,3 +48,65 @@ test('node version check rejects unsupported test runtimes before native modules
       'ChatLab tests require Node.js >=24 <25. Current Node.js is 22.20.0. Switch to Node 24 before running tests.',
   })
 })
+
+test('test run temp root is removed after success and exceptions', () => {
+  let successfulRoot = ''
+  withTestRunTempRoot((tempRoot) => {
+    successfulRoot = tempRoot
+    writeFileSync(`${tempRoot}/success.txt`, 'ok')
+    assert.equal(existsSync(tempRoot), true)
+  })
+  assert.equal(existsSync(successfulRoot), false)
+
+  let failedRoot = ''
+  assert.throws(
+    () =>
+      withTestRunTempRoot((tempRoot) => {
+        failedRoot = tempRoot
+        throw new Error('simulated test runner failure')
+      }),
+    /simulated test runner failure/
+  )
+  assert.equal(existsSync(failedRoot), false)
+})
+
+test('test subprocesses receive the owned run root as every temp environment entry', () => {
+  const env = buildTestEnvironment('/tmp/chatlab/tests/run-example', { KEEP_ME: 'yes' })
+  assert.equal(env.TMPDIR, '/tmp/chatlab/tests/run-example')
+  assert.equal(env.CHATLAB_TEST_TMPDIR, '/tmp/chatlab/tests/run-example')
+  assert.equal(env[CHATLAB_TEMP_ROOT_ENV], '/tmp/chatlab/tests/run-example')
+  assert.equal(env.KEEP_ME, 'yes')
+})
+
+test('interrupted child exits before its owned test run temp root is removed', () => {
+  let tempRoot = ''
+  const result = withTestRunTempRoot((root) => {
+    tempRoot = root
+    return spawnSync(process.execPath, ['-e', "process.kill(process.pid, 'SIGTERM')"], {
+      env: buildTestEnvironment(root),
+    })
+  })
+
+  assert.equal(result.signal, 'SIGTERM')
+  assert.equal(existsSync(tempRoot), false)
+})
+
+test('parallel test runs receive isolated temp roots and never remove each other', () => {
+  let firstRoot = ''
+  let secondRoot = ''
+
+  withTestRunTempRoot((rootA) => {
+    firstRoot = rootA
+    withTestRunTempRoot((rootB) => {
+      secondRoot = rootB
+      assert.notEqual(rootA, rootB)
+      assert.equal(existsSync(rootA), true)
+      assert.equal(existsSync(rootB), true)
+    })
+    assert.equal(existsSync(rootA), true)
+    assert.equal(existsSync(secondRoot), false)
+  })
+
+  assert.equal(existsSync(firstRoot), false)
+  assert.equal(existsSync(secondRoot), false)
+})