diff --git a/test/helpers.ts b/test/helpers.ts
index 90d6898b..57600802 100644
--- a/test/helpers.ts
+++ b/test/helpers.ts
@@ -238,6 +238,24 @@ export function createSession(
   return envelope.result.sessionId;
 }
 
+// An interactive bash for a test. `--norc --noprofile` keep it from reading
+// ~/.bashrc and ~/.profile: a startup file that prompts, prints or ends the
+// shell breaks the commands that the test types (a mise "Trust them?" prompt
+// swallowed one).
+export const HERMETIC_BASH = ['/bin/bash', '--norc', '--noprofile', '-i'];
+
+// Like createSession with HERMETIC_BASH. HISTFILE=/dev/null keeps the shell
+// from reading or writing ~/.bash_history.
+export function createBashSession(
+  testHome: string,
+  options: CreateSessionOptions = {},
+): string {
+  return createSession(testHome, HERMETIC_BASH, {
+    ...options,
+    env: { HISTFILE: '/dev/null', ...options.env },
+  });
+}
+
 export function destroySession(testHome: string, sessionId: string): void {
   if (sessionId.length === 0) {
     return;
diff --git a/test/integration/batch.test.ts b/test/integration/batch.test.ts
index 33a7bc9a..00075822 100644
--- a/test/integration/batch.test.ts
+++ b/test/integration/batch.test.ts
@@ -11,6 +11,7 @@ import type { CommandErrorEnvelope } from '../../src/protocol/envelope.js';
 
 import {
   cleanupHome,
+  createBashSession,
   createSession,
   destroySession,
   runCli,
@@ -170,7 +171,7 @@ describe('batch command integration', { timeout: 45_000 }, () => {
   });
 
   it('reads the step array from --file', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(500);
 
     const stepsPath = join(testHome, 'plan.json');
diff --git a/test/integration/run.test.ts b/test/integration/run.test.ts
index 2193c31a..f827c723 100644
--- a/test/integration/run.test.ts
+++ b/test/integration/run.test.ts
@@ -13,6 +13,7 @@ import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 
 import {
   cleanupHome,
+  createBashSession,
   createSession,
   destroySession,
   readEvents,
@@ -122,7 +123,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('returns immediately with --no-wait', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(500);
 
     const result = runCli(
@@ -148,7 +149,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('reads command from --file', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(500);
 
     const scriptPath = join(testHome, 'test-script.sh');
@@ -171,7 +172,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('handles multiline command input', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(1000);
 
     const result = runCli(
@@ -198,7 +199,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('waits for the command to complete before reporting success', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(1000);
 
     const start = Date.now();
@@ -247,7 +248,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('records input_run event in the event log', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(500);
 
     const result = runCli(
@@ -329,7 +330,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('returns timedOut when run completion is not observed within timeout', async () => {
-    sessionId = createSession(testHome, ['/bin/bash']);
+    sessionId = createBashSession(testHome);
     await sleep(500);
 
     const result = runCli(
@@ -506,13 +507,9 @@ describe('run command integration', { timeout: 45_000 }, () => {
   );
 
   it('does not log postamble cursor controls when shell echo is disabled', async () => {
-    sessionId = createSession(
-      testHome,
-      ['/bin/bash', '--noprofile', '--norc'],
-      {
-        cols: WIDE_ARTIFACT_PROOF_COLS,
-      },
-    );
+    sessionId = createBashSession(testHome, {
+      cols: WIDE_ARTIFACT_PROOF_COLS,
+    });
     await sleep(1000);
 
     const disableEchoResult = runCli(
@@ -590,7 +587,7 @@ describe('run command integration', { timeout: 45_000 }, () => {
   });
 
   it('records structured run completion without leaking sentinel text to artifacts', async () => {
-    sessionId = createSession(testHome, ['/bin/bash'], {
+    sessionId = createBashSession(testHome, {
       cols: WIDE_ARTIFACT_PROOF_COLS,
     });
     await sleep(1000);
diff --git a/test/integration/slow-replay.test.ts b/test/integration/slow-replay.test.ts
index f7717fc3..65be9c82 100644
--- a/test/integration/slow-replay.test.ts
+++ b/test/integration/slow-replay.test.ts
@@ -11,6 +11,7 @@ import {
   cleanupHome,
   createSession,
   destroySession,
+  HERMETIC_BASH,
   readEvents,
   sleep,
 } from '../helpers.js';
@@ -209,7 +210,7 @@ describe(
       // The host default renderer is ghostty-web, so that the catch-up replay
       // after the run uses the slow backend.
       await createSlowSession(
-        ['/bin/bash'],
+        HERMETIC_BASH,
         {
           AGENT_TTY_RENDERER: 'ghostty-web',
           AGENT_TTY_TEST_REPLAY_MS_PER_EVENT: '100',