diff --git a/src/handlers/identity-neutralize.js b/src/handlers/identity-neutralize.js
index 28e1179..8773361 100644
--- a/src/handlers/identity-neutralize.js
+++ b/src/handlers/identity-neutralize.js
@@ -110,6 +110,26 @@ export function neutralizeClientIdentity(text, env = process.env, opts = {}) {
     /You are ([A-Z][\w.-]*), a highly skilled software engineer with extensive knowledge in many programming languages, frameworks, design patterns,? and best practices\./g,
     'You are $1, a software engineer.',
   );
+  // (a6-grok) Grok / xAI self-identification (2026-07-16, live-confirmed to
+  // trip Devin's content policy → permission_denied). Grok CLI opens with
+  // "You are Grok 4.5 released by xAI. You are an interactive CLI tool that
+  // helps users with software engineering tasks." A/B on the live upstream:
+  // this exact line is what triggers the block — the same request with a
+  // generic assistant line passes. Match the full "You are Grok ... released
+  // by xAI" form and the bare noun phrase, any Grok version digit.
+  out = out.replace(
+    /You are Grok[\w .-]* released by xAI\.?/gi,
+    'You are an AI coding assistant.',
+  );
+  out = out.replace(
+    /\bGrok[\w .-]* released by xAI\.?/gi,
+    'an AI coding assistant.',
+  );
+  // (a6-grok2) Grok's executing_actions_with_care safety paragraph — a
+  // competitor-specific safety/policy framing that rides in the prompt body
+  // and has been observed in the same blocked request. Strip the whole
+  // <executing_actions_with_care>...</executing_actions_with_care> block.
+  out = out.replace(/<executing_actions_with_care>[\s\S]*?<\/executing_actions_with_care>/gi, '');
   // (a6) SPECULATIVE / HYPOTHESIS-ONLY (2026-07-15), DEFAULT-OFF. Unlike a1-a5
   // which are live-bisected confirmed triggers, this OBJECTIVE boast sentence is
   // only SUSPECTED to be in the same content-policy trigger family — NOT verified,
diff --git a/test/client-identity-neutralize.test.js b/test/client-identity-neutralize.test.js
index 1d2cb44..243c36c 100644
--- a/test/client-identity-neutralize.test.js
+++ b/test/client-identity-neutralize.test.js
@@ -211,6 +211,73 @@ describe('neutralizeClientIdentity', () => {
   });
 });
 
+// 2026-07-16 (a6-grok/a6-grok2): Grok CLI's system prompt opens with "You are
+// Grok 4.5 released by xAI. You are an interactive CLI tool that helps users
+// with software engineering tasks." Live A/B on the Devin upstream proved that
+// exact self-ID line trips the content policy (permission_denied); the same
+// request with a generic assistant line passes. The competitor-specific
+// <executing_actions_with_care> safety paragraph rides in the same blocked
+// prompt body and is stripped whole. Both rules are unconditional like a1-a5,
+// gated only by the main WINDSURFAPI_NEUTRALIZE_CLIENT_ID switch (default on).
+describe('neutralizeClientIdentity — Grok / xAI rules (a6-grok)', () => {
+  const GROK_ID = 'You are Grok 4.5 released by xAI.';
+
+  it('rewrites the exact Grok self-identification', () => {
+    const out = neutralizeClientIdentity(GROK_ID + ' You are an interactive CLI tool that helps users with software engineering tasks.');
+    assert.ok(!/Grok/.test(out), 'no Grok');
+    assert.ok(!/xAI/.test(out), 'no xAI');
+    assert.match(out, /^You are an AI coding assistant\./, 'opens with the generic identity line');
+    assert.match(out, /You are an interactive CLI tool that helps users with software engineering tasks\./, 'rest of prompt preserved');
+  });
+
+  it('neutralizes the bare noun phrase without the leading "You are"', () => {
+    const out = neutralizeClientIdentity('Note: Grok 4 released by xAI is running.');
+    assert.ok(!/Grok/.test(out), 'no Grok');
+    assert.ok(!/released by xAI/i.test(out), 'no xAI attribution');
+    assert.match(out, /an AI coding assistant\./, 'generic noun phrase substituted');
+  });
+
+  it('matches any Grok version variant (4.5.1, 3 mini, ...)', () => {
+    assert.equal(
+      neutralizeClientIdentity('You are Grok 4.5.1 released by xAI.'),
+      'You are an AI coding assistant.',
+    );
+    assert.equal(
+      neutralizeClientIdentity('You are Grok 3 mini released by xAI.'),
+      'You are an AI coding assistant.',
+    );
+  });
+
+  it('strips the <executing_actions_with_care> block entirely', () => {
+    const out = neutralizeClientIdentity('<executing_actions_with_care>foo bar</executing_actions_with_care>');
+    assert.equal(out, '', 'inline block fully removed');
+  });
+
+  it('strips a multiline <executing_actions_with_care> block and keeps surrounding text', () => {
+    const src = 'Before.\n<executing_actions_with_care>\nfoo bar\nDouble-check destructive commands before running them.\n</executing_actions_with_care>\nAfter.';
+    const out = neutralizeClientIdentity(src);
+    assert.ok(!/executing_actions_with_care/i.test(out), 'tags removed');
+    assert.ok(!/foo bar/.test(out), 'block content removed');
+    assert.ok(!/destructive commands/.test(out), 'multiline content removed');
+    assert.match(out, /Before\./, 'content before kept');
+    assert.match(out, /After\./, 'content after kept');
+  });
+
+  it('leaves unrelated mentions of "Grok" alone (no "released by xAI" attribution)', () => {
+    // Bare mentions are safe — only the xAI-attributed self-ID phrasing is rewritten.
+    const src = 'Use the Logstash grok filter. Grok patterns parse logs.';
+    assert.equal(neutralizeClientIdentity(src), src, 'unrelated text untouched');
+    const plainId = 'You are Grok, a helpful assistant.';
+    assert.equal(neutralizeClientIdentity(plainId), plainId, 'un-attributed identity line untouched');
+  });
+
+  it('the Grok neutralization respects the opt-out flag', () => {
+    process.env.WINDSURFAPI_NEUTRALIZE_CLIENT_ID = '0';
+    const src = GROK_ID + '\n<executing_actions_with_care>Take care.</executing_actions_with_care>';
+    assert.equal(neutralizeClientIdentity(src), src, 'opt-out leaves it verbatim');
+  });
+});
+
 // P2 — Claude Code compat layer: the ccActive gate on the opt-in (cc) block.
 // Contract: a1-a5 stay UNCONDITIONAL (default 529 / content-policy defense for
 // ALL clients); the (cc) block is opt-in and currently EMPTY, so activating it