fix(codex): normalize null instructions across responses paths

internal/runtime/executor/codex_executor.go

@@ -114,10 +114,7 @@ func (e *CodexExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, re
 	body, _ = sjson.DeleteBytes(body, "prompt_cache_retention")
 	body, _ = sjson.DeleteBytes(body, "safety_identifier")
 	body, _ = sjson.DeleteBytes(body, "stream_options")
-	instructions := gjson.GetBytes(body, "instructions")
+	body = normalizeCodexInstructions(body)
-	if !instructions.Exists() || instructions.Type == gjson.Null {
-		body, _ = sjson.SetBytes(body, "instructions", "")
-	}
 
 	url := strings.TrimSuffix(baseURL, "/") + "/responses"
 	httpReq, err := e.cacheHelper(ctx, from, url, req, body)
@@ -315,9 +312,7 @@ func (e *CodexExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Au
 	body, _ = sjson.DeleteBytes(body, "safety_identifier")
 	body, _ = sjson.DeleteBytes(body, "stream_options")
 	body, _ = sjson.SetBytes(body, "model", baseModel)
-	if !gjson.GetBytes(body, "instructions").Exists() {
+	body = normalizeCodexInstructions(body)
-		body, _ = sjson.SetBytes(body, "instructions", "")
-	}
 
 	url := strings.TrimSuffix(baseURL, "/") + "/responses"
 	httpReq, err := e.cacheHelper(ctx, from, url, req, body)
@@ -420,9 +415,7 @@ func (e *CodexExecutor) CountTokens(ctx context.Context, auth *cliproxyauth.Auth
 	body, _ = sjson.DeleteBytes(body, "safety_identifier")
 	body, _ = sjson.DeleteBytes(body, "stream_options")
 	body, _ = sjson.SetBytes(body, "stream", false)
-	if !gjson.GetBytes(body, "instructions").Exists() {
+	body = normalizeCodexInstructions(body)
-		body, _ = sjson.SetBytes(body, "instructions", "")
-	}
 
 	enc, err := tokenizerForCodexModel(baseModel)
 	if err != nil {
@@ -700,6 +693,14 @@ func newCodexStatusErr(statusCode int, body []byte) statusErr {
 	return err
 }
 
+func normalizeCodexInstructions(body []byte) []byte {
+	instructions := gjson.GetBytes(body, "instructions")
+	if !instructions.Exists() || instructions.Type == gjson.Null {
+		body, _ = sjson.SetBytes(body, "instructions", "")
+	}
+	return body
+}
+
 func isCodexModelCapacityError(errorBody []byte) bool {
 	if len(errorBody) == 0 {
 		return false

internal/runtime/executor/codex_executor_instructions_test.go

@@ -52,3 +52,72 @@ func TestCodexExecutorExecuteNormalizesNullInstructions(t *testing.T) {
 		t.Fatalf("instructions = %q, want empty string", gjson.GetBytes(gotBody, "instructions").String())
 	}
 }
+
+func TestCodexExecutorExecuteStreamNormalizesNullInstructions(t *testing.T) {
+	var gotPath string
+	var gotBody []byte
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotPath = r.URL.Path
+		body, _ := io.ReadAll(r.Body)
+		gotBody = body
+		w.Header().Set("Content-Type", "text/event-stream")
+		_, _ = w.Write([]byte("data: {\"type\":\"response.completed\",\"response\":{\"id\":\"resp_1\",\"object\":\"response\",\"created_at\":0,\"status\":\"completed\",\"background\":false,\"error\":null}}\n\n"))
+	}))
+	defer server.Close()
+
+	executor := NewCodexExecutor(&config.Config{})
+	auth := &cliproxyauth.Auth{Attributes: map[string]string{
+		"base_url": server.URL,
+		"api_key":  "test",
+	}}
+
+	result, err := executor.ExecuteStream(context.Background(), auth, cliproxyexecutor.Request{
+		Model:   "gpt-5.4",
+		Payload: []byte(`{"model":"gpt-5.4","instructions":null,"input":"hello"}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FromString("openai-response"),
+		Stream:       true,
+	})
+	if err != nil {
+		t.Fatalf("ExecuteStream error: %v", err)
+	}
+	for range result.Chunks {
+	}
+	if gotPath != "/responses" {
+		t.Fatalf("path = %q, want %q", gotPath, "/responses")
+	}
+	if gjson.GetBytes(gotBody, "instructions").Type != gjson.String {
+		t.Fatalf("instructions type = %v, want string", gjson.GetBytes(gotBody, "instructions").Type)
+	}
+	if gjson.GetBytes(gotBody, "instructions").String() != "" {
+		t.Fatalf("instructions = %q, want empty string", gjson.GetBytes(gotBody, "instructions").String())
+	}
+}
+
+func TestCodexExecutorCountTokensTreatsNullInstructionsAsEmpty(t *testing.T) {
+	executor := NewCodexExecutor(&config.Config{})
+
+	nullResp, err := executor.CountTokens(context.Background(), nil, cliproxyexecutor.Request{
+		Model:   "gpt-5.4",
+		Payload: []byte(`{"model":"gpt-5.4","instructions":null,"input":"hello"}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FromString("openai-response"),
+	})
+	if err != nil {
+		t.Fatalf("CountTokens(null) error: %v", err)
+	}
+
+	emptyResp, err := executor.CountTokens(context.Background(), nil, cliproxyexecutor.Request{
+		Model:   "gpt-5.4",
+		Payload: []byte(`{"model":"gpt-5.4","instructions":"","input":"hello"}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FromString("openai-response"),
+	})
+	if err != nil {
+		t.Fatalf("CountTokens(empty) error: %v", err)
+	}
+
+	if string(nullResp.Payload) != string(emptyResp.Payload) {
+		t.Fatalf("token count payload mismatch:\nnull=%s\nempty=%s", string(nullResp.Payload), string(emptyResp.Payload))
+	}
+}