fix(gemini): handle "[DONE]" chunk, trim "data:" prefix, and remove session_id from requests

- Adjusted stream handling to skip "[DONE]" chunks.
- Ensured "data:" prefix is trimmed for non-prefixed input in translation.
- Removed `session_id` from request bodies before processing.

internal/api/handlers/gemini/gemini-cli_handlers.go

@@ -193,7 +193,14 @@ func (h *GeminiCLIAPIHandler) forwardCLIStream(c *gin.Context, flusher http.Flus
 				return
 			}
 			if alt == "" {
-				_, _ = c.Writer.Write([]byte("data: "))
+				if bytes.Equal(chunk, []byte("data: [DONE]")) || bytes.Equal(chunk, []byte("[DONE]")) {
+					continue
+				}
+
+				if !bytes.HasPrefix(chunk, []byte("data:")) {
+					_, _ = c.Writer.Write([]byte("data: "))
+				}
+
 				_, _ = c.Writer.Write(chunk)
 				_, _ = c.Writer.Write([]byte("\n\n"))
 			} else {

internal/runtime/executor/gemini_executor.go

@@ -59,6 +59,8 @@ func (e *GeminiExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, r
 		url = url + fmt.Sprintf("?$alt=%s", opts.Alt)
 	}
 
+	body, _ = sjson.DeleteBytes(body, "session_id")
+
 	recordAPIRequest(ctx, e.cfg, body)
 	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
 	if err != nil {
@@ -112,6 +114,9 @@ func (e *GeminiExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
 	} else {
 		url = url + fmt.Sprintf("?$alt=%s", opts.Alt)
 	}
+
+	body, _ = sjson.DeleteBytes(body, "session_id")
+
 	recordAPIRequest(ctx, e.cfg, body)
 	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
 	if err != nil {

internal/translator/gemini/gemini-cli/gemini_gemini-cli_response.go

@@ -12,6 +12,8 @@ import (
 	"github.com/tidwall/sjson"
 )
 
+var dataTag = []byte("data:")
+
 // ConvertGeminiResponseToGeminiCLI converts Gemini streaming response format to Gemini CLI single-line JSON format.
 // This function processes various Gemini event types and transforms them into Gemini CLI-compatible JSON responses.
 // It handles thinking content, regular text content, and function calls, outputting single-line JSON
@@ -26,6 +28,11 @@ import (
 // Returns:
 //   - []string: A slice of strings, each containing a Gemini CLI-compatible JSON response.
 func ConvertGeminiResponseToGeminiCLI(_ context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) []string {
+	if !bytes.HasPrefix(rawJSON, dataTag) {
+		return []string{}
+	}
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
+
 	if bytes.Equal(rawJSON, []byte("[DONE]")) {
 		return []string{}
 	}