fix(codex): preserve final_answer responses replay (#1965)

Integrated into release/v3.7.9

open-sse/services/responsesInputSanitizer.ts

@@ -1,4 +1,5 @@
 type JsonRecord = Record<string, unknown>;
+const INTERNAL_ASSISTANT_PHASES = new Set(["commentary"]);
 
 function toRecord(value: unknown): JsonRecord | null {
   return value && typeof value === "object" && !Array.isArray(value) ? (value as JsonRecord) : null;
@@ -15,9 +16,9 @@ export function isInternalAssistantMessage(record: JsonRecord): boolean {
   const phase = typeof record.phase === "string" ? record.phase.trim().toLowerCase() : "";
   if (!phase) return false;
 
-  // OpenCode can send assistant-side commentary/analysis frames in Responses
-  // shape. Those frames are local runtime state, not durable conversation turns.
-  return phase !== "final";
+  // Drop only known internal runtime frames. Visible assistant turns such as
+  // `final` and `final_answer` must survive replay for Codex/OpenCode follow-ups.
+  return INTERNAL_ASSISTANT_PHASES.has(phase);
 }
 
 export function sanitizeResponsesInputItems(items: readonly unknown[], clone = true): unknown[] {

tests/unit/executor-codex.test.ts

@@ -468,6 +468,57 @@ test("CodexExecutor.transformRequest does not replay internal assistant commenta
   assert.equal(result.input[3].type, "function_call_output");
 });
 
+test("CodexExecutor.transformRequest preserves replayed assistant final_answer messages", () => {
+  const executor = new CodexExecutor();
+  rememberResponseConversationState(
+    "resp_prev_final_answer_123",
+    [
+      {
+        type: "message",
+        role: "user",
+        content: [{ type: "input_text", text: "9+10?" }],
+      },
+      {
+        type: "message",
+        role: "assistant",
+        phase: "final_answer",
+        content: [{ type: "output_text", text: "19" }],
+      },
+    ],
+    []
+  );
+
+  const result = executor.transformRequest(
+    "gpt-5.5-low",
+    {
+      _nativeCodexPassthrough: true,
+      previous_response_id: "resp_prev_final_answer_123",
+      input: [
+        {
+          type: "message",
+          role: "user",
+          content: [{ type: "input_text", text: "did you answered?" }],
+        },
+      ],
+      stream: false,
+    },
+    false,
+    { requestEndpointPath: "/responses" }
+  );
+
+  assert.equal(
+    result.input.some((item) => JSON.stringify(item).includes('"text":"19"')),
+    true
+  );
+  assert.equal(
+    result.input.some((item) => {
+      if (!item || typeof item !== "object" || Array.isArray(item)) return false;
+      return item.role === "assistant" && item.phase === "final_answer";
+    }),
+    true
+  );
+});
+
 test("CodexExecutor.transformRequest strips raw internal assistant commentary without dropping useful Responses items", () => {
   const executor = new CodexExecutor();
   const body = {
@@ -490,6 +541,12 @@ test("CodexExecutor.transformRequest strips raw internal assistant commentary wi
         phase: "final",
         content: [{ type: "output_text", text: "Visible final assistant answer." }],
       },
+      {
+        type: "message",
+        role: "assistant",
+        phase: "final_answer",
+        content: [{ type: "output_text", text: "Visible final_answer assistant answer." }],
+      },
       {
         type: "message",
         role: "assistant",
@@ -526,6 +583,12 @@ test("CodexExecutor.transformRequest strips raw internal assistant commentary wi
     result.input.some((item) => JSON.stringify(item).includes("Visible final assistant answer")),
     true
   );
+  assert.equal(
+    result.input.some((item) =>
+      JSON.stringify(item).includes("Visible final_answer assistant answer")
+    ),
+    true
+  );
   assert.equal(
     result.input.some((item) =>
       JSON.stringify(item).includes("Visible assistant history without phase")