fix(image): surface Gemini safety blocks instead of 'no image data'

apps/daemon/src/image-generation/provider.ts

@@ -374,9 +374,10 @@ async function generateGeminiImages(
         failure.publicFacts
       );
     }
-    const part = findGeminiImagePart(await response.json() as unknown);
+    const payload = await response.json() as unknown;
+    const part = findGeminiImagePart(payload);
     if (!part) {
-      throw new ImageGenerationProviderError('upstream_error', 'Gemini returned no image data');
+      throw new ImageGenerationProviderError('upstream_error', geminiNoImageMessage(payload));
     }
     const content = Buffer.from(part.data, 'base64');
     validateImageContent(content);
@@ -577,6 +578,28 @@ function manualImageParameters(request: CreateImageGenerationRequest, provider:
   };
 }
 
+function geminiNoImageMessage(payload: unknown): string {
+  if (!isRecord(payload)) return 'Gemini returned no image data';
+  const blockReason = readNestedString(payload, ['promptFeedback', 'blockReason']);
+  if (blockReason) {
+    const detail = readNestedString(payload, ['promptFeedback', 'blockReasonMessage']);
+    return `Gemini blocked the prompt (${blockReason})${detail ? `: ${detail}` : ''}`;
+  }
+  const candidates = Array.isArray(payload.candidates) ? payload.candidates : [];
+  for (const candidate of candidates) {
+    if (!isRecord(candidate)) continue;
+    const finishReason = typeof candidate.finishReason === 'string' ? candidate.finishReason : undefined;
+    if (!finishReason || finishReason === 'STOP') continue;
+    const parts = isRecord(candidate.content) && Array.isArray(candidate.content.parts) ? candidate.content.parts : [];
+    const text = parts
+      .map(part => (isRecord(part) && typeof part.text === 'string' ? part.text.trim() : ''))
+      .filter(Boolean)
+      .join(' ');
+    return `Gemini blocked the image (${finishReason})${text ? `: ${text}` : ''}`;
+  }
+  return 'Gemini returned no image data';
+}
+
 function findGeminiImagePart(payload: unknown): { data: string; mime: string | null } | undefined {
   if (!isRecord(payload) || !Array.isArray(payload.candidates)) return undefined;
   for (const candidate of payload.candidates) {

apps/daemon/test/integration/image-generation-api.test.ts

@@ -74,6 +74,17 @@ describe('image generation API', () => {
     expect(fetchImpl).not.toHaveBeenCalled();
   });
 
+  it.each([
+    ['prompt blocked', { promptFeedback: { blockReason: 'PROHIBITED_CONTENT' } }, 'PROHIBITED_CONTENT'],
+    ['image safety finish', { candidates: [{ finishReason: 'IMAGE_SAFETY', content: { parts: [{ text: 'I cannot create that image.' }] } }] }, 'IMAGE_SAFETY']
+  ])('surfaces Gemini safety blocks instead of a generic no-image error (%s)', async (_name, payload, reason) => {
+    const config = createDefaultCreatorServicesConfig();
+    config.image.gemini.apiKey = 'test-key';
+    const fetchImpl = vi.fn(async () => Response.json(payload));
+    await expect(generateImageContents({ prompt: 'A city', provider: 'gemini', size: '1024x1024', quality: 'medium', count: 1 }, config, { fetchImpl }))
+      .rejects.toThrow(new RegExp(`blocked.*${reason}`));
+  });
+
   it('generates and serves native ChatGPT artifacts through the existing image API without HTTP fallback', async () => {
     const home = join(dataDir, 'codex');
     await mkdir(home);