Metrics / Success Criteria

• Image descriptions appear within 15 seconds of message arrival
• Cached descriptions appear instantly (no perceptible delay)
• No duplicate API calls for the same image (verified in logs)
• Failed descriptions show a clear placeholder, not an empty bubble or crash
• Chat list preview shows image descriptions, not empty text
• Multi-image messages are visually grouped and readable
• Privacy consent is shown before first API call
• User can toggle descriptions on/off without restarting the app
• Image EXIF metadata is stripped before API upload
• Cost per image is ≤ 1 API call (no retries except on transient failure)