fix: handle empty and non-JSON SSE chunks safely

internal/runtime/executor/antigravity_executor.go

@@ -172,7 +172,12 @@ func (e *AntigravityExecutor) ExecuteStream(ctx context.Context, auth *cliproxya
 			// Only retain usage statistics in the terminal chunk
 			line = FilterSSEUsageMetadata(line)
 
-			chunks := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, bytes.Clone(line), &param)
+			payload := jsonPayload(line)
+			if payload == nil {
+				continue
+			}
+
+			chunks := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, bytes.Clone(payload), &param)
 			for i := range chunks {
 				out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunks[i])}
 			}

internal/translator/antigravity/openai/chat-completions/antigravity_openai_response.go

@@ -45,10 +45,6 @@ func ConvertAntigravityResponseToOpenAI(_ context.Context, _ string, originalReq
 		}
 	}
 
-	if len(bytes.TrimSpace(rawJSON)) == 0 {
-		return []string{}
-	}
-
 	if bytes.Equal(rawJSON, []byte("[DONE]")) {
 		return []string{}
 	}

internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go

@@ -45,10 +45,6 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 		}
 	}
 
-	if len(bytes.TrimSpace(rawJSON)) == 0 {
-		return []string{}
-	}
-
 	if bytes.Equal(rawJSON, []byte("[DONE]")) {
 		return []string{}
 	}