fix: isolate codex stdio turn routing

internal/cloud/code-agent-chat.ts

@@ -214,6 +214,7 @@ export async function handleCodeAgentChat(params = {}, options = {}) {
         toolName: error.toolName
       })
     };
+    if (payload.error?.diagnosis) payload.diagnosis = payload.error.diagnosis;
     if (payload.error?.blocker) payload.blocker = payload.error.blocker;
     if (payload.error?.blockers) payload.blockers = payload.error.blockers;
     if (error.provider) payload.provider = error.provider;
@@ -924,6 +925,7 @@ async function callCodexStdioRunner({ message, conversationId, sessionId, thread
       idleMs: error.idleMs,
       lastActivityAt: error.lastActivityAt,
       waitingFor: error.waitingFor,
+      diagnosis: error.diagnosis,
       providerTrace: error.providerTrace,
       stage: error.stage,
       missingTools: error.missingTools,
@@ -1185,6 +1187,7 @@ function normalizeChatError(error, context = {}) {
   const idleMs = numberErrorField(error.idleMs ?? context.idleMs);
   const lastActivityAt = safeIsoLike(error.lastActivityAt ?? context.lastActivityAt);
   const waitingFor = redactText(error.waitingFor ?? context.waitingFor ?? "");
+  const diagnosis = normalizeDiagnosis(error.diagnosis ?? context.diagnosis ?? error.blocker?.diagnosis ?? null);
   const blocker = structuredBlocker({
     code,
     layer: taxonomy.layer,
@@ -1209,7 +1212,8 @@ function normalizeChatError(error, context = {}) {
     hardTimeoutMs,
     idleMs,
     lastActivityAt,
-    waitingFor
+    waitingFor,
+    diagnosis
   });
   const normalized = {
     code,
@@ -1233,6 +1237,7 @@ function normalizeChatError(error, context = {}) {
     idleMs,
     lastActivityAt,
     waitingFor,
+    diagnosis,
     missingConfig: safeMissingConfig(error),
     blockers
   };
@@ -1429,7 +1434,7 @@ function errorTaxonomy(code, error = {}) {
   };
 }
 
-function structuredBlocker({ code, layer, message, userMessage, retryable, traceId, provider, backend, runner, capabilityLevel, route, toolName, category, blockers, sessionId = null, conversationId = null, stage = null, lastEvent = null, elapsedMs = null, timeoutMs = null, hardTimeoutMs = null, idleMs = null, lastActivityAt = null, waitingFor = null }) {
+function structuredBlocker({ code, layer, message, userMessage, retryable, traceId, provider, backend, runner, capabilityLevel, route, toolName, category, blockers, sessionId = null, conversationId = null, stage = null, lastEvent = null, elapsedMs = null, timeoutMs = null, hardTimeoutMs = null, idleMs = null, lastActivityAt = null, waitingFor = null, diagnosis = null }) {
   return {
     code,
     layer,
@@ -1454,6 +1459,7 @@ function structuredBlocker({ code, layer, message, userMessage, retryable, trace
     idleMs,
     lastActivityAt,
     waitingFor,
+    diagnosis,
     blockerCodes: Array.isArray(blockers) ? blockers.map((blocker) => blocker.code).filter(Boolean) : []
   };
 }
@@ -1485,7 +1491,8 @@ function normalizeBlockers(blockers, fallback) {
       hardTimeoutMs: numberErrorField(blocker.hardTimeoutMs),
       idleMs: numberErrorField(blocker.idleMs),
       lastActivityAt: safeIsoLike(blocker.lastActivityAt),
-      waitingFor: blocker.waitingFor ? redactText(blocker.waitingFor) : null
+      waitingFor: blocker.waitingFor ? redactText(blocker.waitingFor) : null,
+      diagnosis: normalizeDiagnosis(blocker.diagnosis ?? null)
     }));
   if (normalized.length > 0) return normalized;
   return [{
@@ -1498,6 +1505,32 @@ function normalizeBlockers(blockers, fallback) {
   }];
 }
 
+function normalizeDiagnosis(value) {
+  if (!value || typeof value !== "object" || Array.isArray(value)) return null;
+  return {
+    code: value.code ? redactText(value.code) : null,
+    layer: value.layer ? redactText(value.layer) : null,
+    kind: value.kind ? redactText(value.kind) : null,
+    summary: value.summary ? redactText(value.summary) : null,
+    waitingFor: value.waitingFor ? redactText(value.waitingFor) : null,
+    lastActivityAt: safeIsoLike(value.lastActivityAt),
+    idleMs: numberErrorField(value.idleMs),
+    threadId: value.threadId ? redactText(value.threadId) : null,
+    turnId: value.turnId ? redactText(value.turnId) : null,
+    lastRoutedEvent: value.lastRoutedEvent && typeof value.lastRoutedEvent === "object" ? {
+      type: value.lastRoutedEvent.type ?? null,
+      status: value.lastRoutedEvent.status ?? null,
+      label: value.lastRoutedEvent.label ?? null,
+      stage: value.lastRoutedEvent.stage ?? null,
+      toolName: value.lastRoutedEvent.toolName ?? null,
+      itemId: value.lastRoutedEvent.itemId ?? null,
+      waitingFor: value.lastRoutedEvent.waitingFor ?? null,
+      exitCode: numberErrorField(value.lastRoutedEvent.exitCode),
+      durationMs: numberErrorField(value.lastRoutedEvent.durationMs)
+    } : null
+  };
+}
+
 function safeMissingConfig(error) {
   return [
     ...(Array.isArray(error.missingEnv) ? error.missingEnv : []),