refactor(media-understanding): share gemini output extract

src/media-understanding/runner.ts

@@ -32,6 +32,7 @@ import {
   DEFAULT_IMAGE_MODELS,
 } from "./defaults.js";
 import { isMediaUnderstandingSkipError } from "./errors.js";
+import { extractGeminiResponse } from "./output-extract.js";
 import {
   buildMediaUnderstandingRegistry,
   getMediaUnderstandingProvider,
@@ -186,33 +187,6 @@ async function fileExists(filePath?: string | null): Promise<boolean> {
   }
 }
 
-function extractLastJsonObject(raw: string): unknown {
-  const trimmed = raw.trim();
-  const start = trimmed.lastIndexOf("{");
-  if (start === -1) {
-    return null;
-  }
-  const slice = trimmed.slice(start);
-  try {
-    return JSON.parse(slice);
-  } catch {
-    return null;
-  }
-}
-
-function extractGeminiResponse(raw: string): string | null {
-  const payload = extractLastJsonObject(raw);
-  if (!payload || typeof payload !== "object") {
-    return null;
-  }
-  const response = (payload as { response?: unknown }).response;
-  if (typeof response !== "string") {
-    return null;
-  }
-  const trimmed = response.trim();
-  return trimmed || null;
-}
-
 async function probeGeminiCli(): Promise<boolean> {
   const cached = geminiProbeCache.get("gemini");
   if (cached) {