diff --git a/internal/runtime/executor/codex_executor.go b/internal/runtime/executor/codex_executor.go
index a0cbc0d5..30092ec7 100644
--- a/internal/runtime/executor/codex_executor.go
+++ b/internal/runtime/executor/codex_executor.go
@@ -616,6 +616,10 @@ func (e *CodexExecutor) cacheHelper(ctx context.Context, from sdktranslator.Form
 		if promptCacheKey.Exists() {
 			cache.ID = promptCacheKey.String()
 		}
+	} else if from == "openai" {
+		if apiKey := strings.TrimSpace(apiKeyFromContext(ctx)); apiKey != "" {
+			cache.ID = uuid.NewSHA1(uuid.NameSpaceOID, []byte("cli-proxy-api:codex:prompt-cache:"+apiKey)).String()
+		}
 	}
 
 	if cache.ID != "" {
diff --git a/internal/runtime/executor/codex_executor_cache_test.go b/internal/runtime/executor/codex_executor_cache_test.go
new file mode 100644
index 00000000..d6dca031
--- /dev/null
+++ b/internal/runtime/executor/codex_executor_cache_test.go
@@ -0,0 +1,64 @@
+package executor
+
+import (
+	"context"
+	"io"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+	"github.com/tidwall/gjson"
+)
+
+func TestCodexExecutorCacheHelper_OpenAIChatCompletions_StablePromptCacheKeyFromAPIKey(t *testing.T) {
+	recorder := httptest.NewRecorder()
+	ginCtx, _ := gin.CreateTestContext(recorder)
+	ginCtx.Set("apiKey", "test-api-key")
+
+	ctx := context.WithValue(context.Background(), "gin", ginCtx)
+	executor := &CodexExecutor{}
+	rawJSON := []byte(`{"model":"gpt-5.3-codex","stream":true}`)
+	req := cliproxyexecutor.Request{
+		Model:   "gpt-5.3-codex",
+		Payload: []byte(`{"model":"gpt-5.3-codex"}`),
+	}
+	url := "https://example.com/responses"
+
+	httpReq, err := executor.cacheHelper(ctx, sdktranslator.FromString("openai"), url, req, rawJSON)
+	if err != nil {
+		t.Fatalf("cacheHelper error: %v", err)
+	}
+
+	body, errRead := io.ReadAll(httpReq.Body)
+	if errRead != nil {
+		t.Fatalf("read request body: %v", errRead)
+	}
+
+	expectedKey := uuid.NewSHA1(uuid.NameSpaceOID, []byte("cli-proxy-api:codex:prompt-cache:test-api-key")).String()
+	gotKey := gjson.GetBytes(body, "prompt_cache_key").String()
+	if gotKey != expectedKey {
+		t.Fatalf("prompt_cache_key = %q, want %q", gotKey, expectedKey)
+	}
+	if gotConversation := httpReq.Header.Get("Conversation_id"); gotConversation != expectedKey {
+		t.Fatalf("Conversation_id = %q, want %q", gotConversation, expectedKey)
+	}
+	if gotSession := httpReq.Header.Get("Session_id"); gotSession != expectedKey {
+		t.Fatalf("Session_id = %q, want %q", gotSession, expectedKey)
+	}
+
+	httpReq2, err := executor.cacheHelper(ctx, sdktranslator.FromString("openai"), url, req, rawJSON)
+	if err != nil {
+		t.Fatalf("cacheHelper error (second call): %v", err)
+	}
+	body2, errRead2 := io.ReadAll(httpReq2.Body)
+	if errRead2 != nil {
+		t.Fatalf("read request body (second call): %v", errRead2)
+	}
+	gotKey2 := gjson.GetBytes(body2, "prompt_cache_key").String()
+	if gotKey2 != expectedKey {
+		t.Fatalf("prompt_cache_key (second call) = %q, want %q", gotKey2, expectedKey)
+	}
+}