fix: include saved image paths in CLI JSON output (#2070)

Fixes #1910

Summary:
- save image content before returning structured CLI JSON output
- include saved image metadata in `structuredContent.images`
- add coverage for JSON output with image content

Tests:
- `npm test -- tests/daemon/client.test.ts`
- `npx eslint src/daemon/client.ts tests/daemon/client.test.ts && npx
prettier --check src/daemon/client.ts tests/daemon/client.test.ts`

Co-authored-by: Nicholas Roscino <nroscino@google.com>

src/daemon/client.ts

@@ -154,13 +154,8 @@ export async function handleResponse(
   if (response.isError) {
     return JSON.stringify(response.content);
   }
-  if (format === 'json') {
-    if (response.structuredContent) {
-      return JSON.stringify(response.structuredContent);
-    }
-    // Fall-through to text for backward compatibility.
-  }
   const chunks = [];
+  const images: Array<{filePath: string; mimeType: string}> = [];
   for (const content of response.content) {
     if (content.type === 'text') {
       chunks.push(content.text);
@@ -181,10 +176,21 @@ export async function handleResponse(
       const name = crypto.randomUUID();
       const filepath = await getTempFilePath(`${name}${extension}`);
       fs.writeFileSync(filepath, data);
+      images.push({filePath: filepath, mimeType});
       chunks.push(`Saved to ${filepath}.`);
     } else {
       throw new Error('Not supported response content type');
     }
   }
+  if (format === 'json') {
+    if (response.structuredContent) {
+      const structuredContent = {
+        ...response.structuredContent,
+        ...(images.length ? {images} : {}),
+      };
+      return JSON.stringify(structuredContent);
+    }
+    // Fall-through to text for backward compatibility.
+  }
   return format === 'md' ? chunks.join(' ') : JSON.stringify(chunks);
 }

tests/daemon/client.test.ts

@@ -6,6 +6,8 @@
 
 import assert from 'node:assert';
 import crypto from 'node:crypto';
+import {existsSync, rmSync} from 'node:fs';
+import {dirname} from 'node:path';
 import {describe, it, afterEach, beforeEach} from 'node:test';
 
 import {
@@ -127,6 +129,43 @@ describe('daemon client', () => {
       assert.ok(response.includes('.png'));
     });
 
+    it('includes saved image file paths in structured JSON responses', async () => {
+      const imageContentResponse = {
+        content: [
+          {
+            type: 'text' as const,
+            text: 'Took a screenshot.',
+          },
+          {
+            type: 'image' as const,
+            data: Buffer.from('image data').toString('base64'),
+            mimeType: 'image/png',
+          },
+        ],
+        structuredContent: {
+          message: 'Took a screenshot.',
+        },
+      };
+      let filePath: string | undefined;
+      try {
+        const response = await handleResponse(imageContentResponse, 'json');
+        const parsed = JSON.parse(response) as {
+          message: string;
+          images: Array<{filePath: string; mimeType: string}>;
+        };
+        assert.strictEqual(parsed.message, 'Took a screenshot.');
+        assert.strictEqual(parsed.images.length, 1);
+        assert.strictEqual(parsed.images[0].mimeType, 'image/png');
+        filePath = parsed.images[0].filePath;
+        assert.ok(filePath.endsWith('.png'));
+        assert.ok(existsSync(filePath));
+      } finally {
+        if (filePath) {
+          rmSync(dirname(filePath), {recursive: true, force: true});
+        }
+      }
+    });
+
     it('uses the webp extension for WebP images', async () => {
       const webpContentResponse = {
         content: [