Docs: Link harness trust guidance

Point installer readers to the harness-specific approval and verification steps on impeccable.style.\n\nAI-assisted: Codex prepared and verified this documentation update under direct maintainer instruction.

.agents/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.agents/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.claude/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.claude/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.cursor/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.cursor/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.gemini/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.gemini/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.github/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.github/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.grok/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.grok/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.hermes/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.hermes/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.kiro/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.kiro/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.opencode/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.opencode/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.pi/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.pi/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.qoder/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.qoder/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.rovodev/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.rovodev/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.trae-cn/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.trae-cn/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.trae/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.trae/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

.vibe/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

.vibe/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.

README.md

@@ -113,6 +113,8 @@ npx impeccable update
 
 Codex users should open `/hooks` after install or update and approve the project hook when prompted. Codex tracks trust by hook definition, so updates that change `.codex/hooks.json` can require approval again. Grok Build users need project folder trust (`/hooks-trust` or launch with `--trust`) before `.grok/hooks/` scripts run.
 
+See [Allow the hook in your harness](https://impeccable.style/docs/hooks#allow-the-hook-in-your-harness) for harness-specific trust and verification steps.
+
 ### Option 2: Git Submodule
 
 For teams that want to keep Impeccable vendored and updated through Git, add this repo as a submodule and link the compiled provider build into your harness folders:

plugin/skills/impeccable/scripts/hook-lib.mjs

@@ -1252,7 +1252,8 @@ export function resolveHarness(env = {}, event = null) {
   if (explicit === 'cursor') return 'cursor';
   if (explicit === 'github') return 'github';
   if (explicit === 'grok') return 'grok';
-  if (explicit === 'claude' || explicit === 'codex') return 'claude';
+  if (explicit === 'claude') return 'claude';
+  if (explicit === 'codex') return 'codex';
   // Grok Build sends camelCase `toolName`/`toolInput`/`hookEventName` and no
   // snake_case pair. GitHub Copilot sends camelCase `toolName`/`toolArgs`.
   // Check Grok first: the old GitHub heuristic (`toolName` and no
@@ -1265,6 +1266,11 @@ export function resolveHarness(env = {}, event = null) {
     return 'github';
   }
   if (typeof event?.conversation_id === 'string' && event.conversation_id) return 'cursor';
+  // Codex turn-scoped events carry `turn_id`. Claude Code does not. Detecting
+  // it here means an already-installed Codex hook emits the Codex Stop
+  // contract without rewriting the hook command to set IMPECCABLE_HOOK_HARNESS.
+  // https://developers.openai.com/codex/hooks#stop
+  if (typeof event?.turn_id === 'string' && event.turn_id) return 'codex';
   return 'claude';
 }
 
@@ -2224,8 +2230,11 @@ export const STOP_MAX_FILES = 20;
  *   { exitCode, stdout, audit, emission? }
  *
  * Never throws; exits silent (and fast) when the session touched no UI
- * files. Output uses the Stop hookSpecificOutput channel: additionalContext
- * is delivered to the model and the conversation continues so it can act.
+ * files. Output goes out on the harness's Stop continuation channel: Claude
+ * Code and Grok Build read hookSpecificOutput.additionalContext, Codex takes
+ * a decision: "block" whose reason becomes the continuation prompt. Either
+ * way the findings reach the model and the conversation continues so it
+ * can act.
  */
 export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), now = Date.now, detector } = {}) {
   const audit = { ts: new Date(now()).toISOString(), event: 'Stop' };
@@ -2256,17 +2265,21 @@ export async function runStopHook({ stdinJson, env = {}, cwd = process.cwd(), no
     audit.harness = harness;
     event = normalizeHookEvent(event, cwd, harness);
 
-    // Claude Code's Stop-hook contract: `stop_hook_active` is true when this
-    // hook is being re-invoked only because a prior invocation kept the turn
-    // alive (here, via hookSpecificOutput.additionalContext). Re-scanning and
-    // re-blocking now would loop until Claude Code's consecutive-block cap
-    // force-ends the turn (issue #400). The prior fire already surfaced the
-    // findings; whether to act on them is the agent's call. Exit fast with no
-    // output before any scan. Claude sends `stop_hook_active`; Grok sends
-    // `stopHookActive`, copied onto the snake_case field above. The strict
-    // `=== true` is a no-op when the field is absent. This guard makes the
-    // loop impossible regardless of the finding cache key's line-number
-    // sensitivity (out of scope here; see findingCacheKey).
+    // Stop-hook re-entry guard: `stop_hook_active` is true when this hook is
+    // being re-invoked only because a prior invocation kept the turn alive
+    // (Claude Code via hookSpecificOutput.additionalContext, Codex via a
+    // decision: "block" continuation). Re-scanning and re-blocking now could
+    // loop (issue #400). The prior fire already surfaced the findings;
+    // whether to act on them is the agent's call. Exit fast with no output
+    // before any scan. Claude Code and Codex both send this field: Codex
+    // mirrors the Claude contract (StopCommandInput in
+    // codex-rs/hooks/src/schema.rs) and latches it true for the rest of the
+    // turn once a block is honored (codex-rs/core/src/session/turn.rs). Grok
+    // sends `stopHookActive`, copied onto the snake_case field above. Cursor
+    // and GitHub Copilot omit the field, so the strict `=== true` is a no-op
+    // for them. The guard makes the loop impossible regardless of the finding
+    // cache key's line-number sensitivity (out of scope here; see
+    // findingCacheKey).
     if (event.stop_hook_active === true) {
       return result({ skipped: 'stop-hook-active', durationMs: Date.now() - started });
     }
@@ -2419,6 +2432,15 @@ export function payload(text, eventName = 'PostToolUse', harness = 'claude') {
   if (harness === 'github') {
     return JSON.stringify({ additionalContext: text });
   }
+  // Codex shares Claude Code's PostToolUse additional-context shape, but its
+  // Stop schema rejects unknown fields. Findings that should continue the
+  // turn must be a top-level blocking decision.
+  // https://developers.openai.com/codex/hooks#stop (schema of record:
+  // codex-rs/hooks/src/schema.rs, StopCommandOutputWire)
+  if (harness === 'codex' && eventName === 'Stop') {
+    if (!String(text ?? '').trim()) return '';
+    return JSON.stringify({ decision: 'block', reason: text });
+  }
   return JSON.stringify({
     hookSpecificOutput: { hookEventName: eventName, additionalContext: text },
   });

plugin/skills/impeccable/scripts/hook.mjs

@@ -12,7 +12,7 @@
  *     discards that stdout; the scan still warms the session cache for Stop.
  *   - Stop: runs the FULL detector rule set over every UI file touched this
  *     session (the deep pass), deduped against what the per-edit pass already
- *     surfaced, and emits once via the Stop additionalContext channel.
+ *     surfaced, and emits once via the harness-specific continuation channel.
  *
  * Contract: never break a turn. Always exit 0. Clean files emit a small ack
  * unless quiet mode is enabled; a clean Stop pass is silent.