feat(codex): pass base model to enable conditional image_generation tool injection

- Modified `ensureImageGenerationTool` to accept `baseModel` for conditional logic.
- Ensured `gpt-5.3-codex-spark` models bypass image_generation tool injection.
- Updated relevant tests and executor logic to reflect changes.

internal/runtime/executor/codex_executor.go

@@ -180,7 +180,7 @@ func (e *CodexExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, re
 	body, _ = sjson.DeleteBytes(body, "safety_identifier")
 	body, _ = sjson.DeleteBytes(body, "stream_options")
 	body = normalizeCodexInstructions(body)
-	body = ensureImageGenerationTool(body)
+	body = ensureImageGenerationTool(body, baseModel)
 
 	url := strings.TrimSuffix(baseURL, "/") + "/responses"
 	httpReq, err := e.cacheHelper(ctx, from, url, req, body)
@@ -327,7 +327,7 @@ func (e *CodexExecutor) executeCompact(ctx context.Context, auth *cliproxyauth.A
 	body, _ = sjson.SetBytes(body, "model", baseModel)
 	body, _ = sjson.DeleteBytes(body, "stream")
 	body = normalizeCodexInstructions(body)
-	body = ensureImageGenerationTool(body)
+	body = ensureImageGenerationTool(body, baseModel)
 
 	url := strings.TrimSuffix(baseURL, "/") + "/responses/compact"
 	httpReq, err := e.cacheHelper(ctx, from, url, req, body)
@@ -422,7 +422,7 @@ func (e *CodexExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Au
 	body, _ = sjson.DeleteBytes(body, "stream_options")
 	body, _ = sjson.SetBytes(body, "model", baseModel)
 	body = normalizeCodexInstructions(body)
-	body = ensureImageGenerationTool(body)
+	body = ensureImageGenerationTool(body, baseModel)
 
 	url := strings.TrimSuffix(baseURL, "/") + "/responses"
 	httpReq, err := e.cacheHelper(ctx, from, url, req, body)
@@ -827,7 +827,11 @@ func normalizeCodexInstructions(body []byte) []byte {
 var imageGenToolJSON = []byte(`{"type":"image_generation","output_format":"png"}`)
 var imageGenToolArrayJSON = []byte(`[{"type":"image_generation","output_format":"png"}]`)
 
-func ensureImageGenerationTool(body []byte) []byte {
+func ensureImageGenerationTool(body []byte, baseModel string) []byte {
+	if strings.HasSuffix(baseModel, "spark") {
+		return body
+	}
+
 	tools := gjson.GetBytes(body, "tools")
 	if !tools.Exists() || !tools.IsArray() {
 		body, _ = sjson.SetRawBytes(body, "tools", imageGenToolArrayJSON)

internal/runtime/executor/codex_executor_imagegen_test.go

@@ -8,7 +8,7 @@ import (
 
 func TestEnsureImageGenerationTool_NoTools(t *testing.T) {
 	body := []byte(`{"model":"gpt-5.4","input":"draw a cat"}`)
-	result := ensureImageGenerationTool(body)
+	result := ensureImageGenerationTool(body, "gpt-5.4")
 
 	tools := gjson.GetBytes(result, "tools")
 	if !tools.IsArray() {
@@ -28,7 +28,7 @@ func TestEnsureImageGenerationTool_NoTools(t *testing.T) {
 
 func TestEnsureImageGenerationTool_ExistingToolsWithoutImageGen(t *testing.T) {
 	body := []byte(`{"model":"gpt-5.4","tools":[{"type":"function","name":"get_weather","parameters":{}}]}`)
-	result := ensureImageGenerationTool(body)
+	result := ensureImageGenerationTool(body, "gpt-5.4")
 
 	tools := gjson.GetBytes(result, "tools")
 	arr := tools.Array()
@@ -45,7 +45,7 @@ func TestEnsureImageGenerationTool_ExistingToolsWithoutImageGen(t *testing.T) {
 
 func TestEnsureImageGenerationTool_AlreadyPresent(t *testing.T) {
 	body := []byte(`{"model":"gpt-5.4","tools":[{"type":"image_generation","output_format":"webp"},{"type":"function","name":"f1"}]}`)
-	result := ensureImageGenerationTool(body)
+	result := ensureImageGenerationTool(body, "gpt-5.4")
 
 	tools := gjson.GetBytes(result, "tools")
 	arr := tools.Array()
@@ -59,7 +59,7 @@ func TestEnsureImageGenerationTool_AlreadyPresent(t *testing.T) {
 
 func TestEnsureImageGenerationTool_EmptyToolsArray(t *testing.T) {
 	body := []byte(`{"model":"gpt-5.4","tools":[]}`)
-	result := ensureImageGenerationTool(body)
+	result := ensureImageGenerationTool(body, "gpt-5.4")
 
 	tools := gjson.GetBytes(result, "tools")
 	arr := tools.Array()
@@ -73,7 +73,7 @@ func TestEnsureImageGenerationTool_EmptyToolsArray(t *testing.T) {
 
 func TestEnsureImageGenerationTool_WebSearchAndImageGen(t *testing.T) {
 	body := []byte(`{"model":"gpt-5.4","tools":[{"type":"web_search"}]}`)
-	result := ensureImageGenerationTool(body)
+	result := ensureImageGenerationTool(body, "gpt-5.4")
 
 	tools := gjson.GetBytes(result, "tools")
 	arr := tools.Array()
@@ -87,3 +87,15 @@ func TestEnsureImageGenerationTool_WebSearchAndImageGen(t *testing.T) {
 		t.Fatalf("expected second tool type=image_generation, got %s", arr[1].Get("type").String())
 	}
 }
+
+func TestEnsureImageGenerationTool_GPT53CodexSparkDoesNotInjectTool(t *testing.T) {
+	body := []byte(`{"model":"gpt-5.3-codex-spark","input":"draw a cat"}`)
+	result := ensureImageGenerationTool(body, "gpt-5.3-codex-spark")
+
+	if string(result) != string(body) {
+		t.Fatalf("expected body to be unchanged, got %s", string(result))
+	}
+	if gjson.GetBytes(result, "tools").Exists() {
+		t.Fatalf("expected no tools for gpt-5.3-codex-spark, got %s", gjson.GetBytes(result, "tools").Raw)
+	}
+}