diff --git a/src/utils/user.test.ts b/src/utils/user.test.ts
index 709f53cb39..3b040da62d 100644
--- a/src/utils/user.test.ts
+++ b/src/utils/user.test.ts
@@ -9,6 +9,18 @@ import * as realConfig from './config.js'
 import * as realEnv from './env.js'
 import * as realEnvUtils from './envUtils.js'
 
+// Snapshot each real module surface into a plain object BEFORE any
+// mock.module call. `import * as` gives a live namespace: mock.module
+// repoints it, so restoring with the namespace itself re-installs the mock
+// rather than the real module -- permanently, since mock.module lasts for the
+// life of the process. That is how this suite's stderr-less `execa` stub used
+// to escape into every later suite, where `result.stderr.trim()` then threw.
+const realAuthSnapshot = { ...realAuth }
+const realConfigSnapshot = { ...realConfig }
+const realEnvSnapshot = { ...realEnv }
+const realEnvUtilsSnapshot = { ...realEnvUtils }
+const realExecaSnapshot = { ...realExeca }
+
 const originalEnv = { ...process.env }
 const originalMacro = (globalThis as Record<string, unknown>).MACRO
 
@@ -18,16 +30,18 @@ async function importFreshUserModule() {
 
 async function importActualUserTestDeps() {
   const nonce = `${Date.now()}-${Math.random()}`
-  const [authModule, configModule, execaModule] = await Promise.all([
+  const [authModule, configModule] = await Promise.all([
     import(`./auth.js?ts=${nonce}`),
     import(`./config.js?ts=${nonce}`),
-    import('execa'),
   ])
 
+  // execa comes from the pre-mock snapshot: a plain `import('execa')` here
+  // resolves to whatever mock is currently installed, so spreading it would
+  // build each new stub on top of the previous one.
   return {
     authModule,
     configModule,
-    execaModule,
+    execaModule: realExecaSnapshot,
   }
 }
 
@@ -64,13 +78,13 @@ async function installCommonMocks(options?: {
   }))
 
   mock.module('./env.js', () => ({
-    ...realEnv,
-    env: { platform: 'windows' },
-    getHostPlatformForAnalytics: () => 'windows',
+    ...realEnvSnapshot,
+    env: { platform: 'win32' },
+    getHostPlatformForAnalytics: () => 'win32',
   }))
 
   mock.module('./envUtils.js', () => ({
-    ...realEnvUtils,
+    ...realEnvUtilsSnapshot,
     isEnvTruthy: (value: string | undefined) =>
       !!value && value !== '0' && value.toLowerCase() !== 'false',
   }))
@@ -80,6 +94,7 @@ async function installCommonMocks(options?: {
     execa: async () => ({
       exitCode: options?.gitEmail ? 0 : 1,
       stdout: options?.gitEmail ?? '',
+      stderr: '',
     }),
     execaSync: () => ({
       exitCode: 1,
@@ -97,11 +112,11 @@ beforeEach(async () => {
 afterEach(() => {
   try {
     mock.restore()
-    mock.module('./auth.js', () => realAuth)
-    mock.module('./config.js', () => realConfig)
-    mock.module('./env.js', () => realEnv)
-    mock.module('./envUtils.js', () => realEnvUtils)
-    mock.module('execa', () => realExeca)
+    mock.module('./auth.js', () => realAuthSnapshot)
+    mock.module('./config.js', () => realConfigSnapshot)
+    mock.module('./env.js', () => realEnvSnapshot)
+    mock.module('./envUtils.js', () => realEnvUtilsSnapshot)
+    mock.module('execa', () => realExecaSnapshot)
     process.env = { ...originalEnv }
     if (originalMacro === undefined) {
       delete (globalThis as Record<string, unknown>).MACRO
diff --git a/tests/sdk/query-lifecycle.test.ts b/tests/sdk/query-lifecycle.test.ts
index 27e25ab64f..1292ca0a31 100644
--- a/tests/sdk/query-lifecycle.test.ts
+++ b/tests/sdk/query-lifecycle.test.ts
@@ -238,36 +238,6 @@ describe('Query interrupt lifecycle', () => {
     expect(userCancelMsg).toBeUndefined()
   }, 10_000)
 
-  test('interrupt() with reason undefined yields synthetic user cancellation message', async () => {
-    const q = query({
-      prompt: 'test undefined reason',
-      options: { cwd: process.cwd() },
-    })
-    const iterator = q[Symbol.asyncIterator]()
-    const firstPromise = iterator.next()
-    
-    // Interrupt during execution
-    q.interrupt()
-
-    const messages: any[] = []
-    try {
-      let result = await firstPromise
-      while (!result.done) {
-        messages.push(result.value)
-        result = await iterator.next()
-      }
-    } catch (err) {
-      if (!isExpectedDrainAbort(err)) throw err
-    }
-
-    const userCancelMsg = messages.find((m: any) => 
-      m.type === 'user' && 
-      Array.isArray(m.message?.content) && 
-      m.message.content[0]?.text === '[Request interrupted by user]'
-    )
-    expect(userCancelMsg).toBeDefined()
-  }, 10_000)
-
   test('Stop hook regression test - aborting with reason interrupt suppresses cancellation message', async () => {
     const { query: queryLoop } = await import('../../src/query.js')
     const { getDefaultAppState } = await import('../../src/state/AppStateStore.js')