## Summary
Adds a new `screenshot-diff` tool for comparing mobile screenshots
during UI QA and visual regression checks. The tool can compare two
saved PNGs, or compare one saved PNG against one live full-resolution
device capture, then returns a compact text summary and generated diff
artifacts.
## Context
Mobile UI validation often needs more than a single screenshot: small
layout, color, typography,
copy, clipping, and regression changes are easy to miss manually. This
feature gives agents a
deterministic before/after comparison path while keeping
`screenshot-diff` as supporting evidence.
## What Changed
- Registered a new `screenshot-diff` tool in the tool server.
- Supports saved PNG comparisons and one-sided live capture via
`captureBaseline` or
`captureCurrent`.
- Adds PNG diffing with fixed internal defaults, changed-region
detection, status-bar-band
ignoring, full-size diff output, and downscaled context diff output.
- Adds optional OCR/text analysis for moved, appeared, disappeared,
changed, and restyled text.
- Updates MCP content rendering to attach the downscaled context diff
image plus the text summary.
1. Capture a stable full-resolution baseline.
2. Perform an interaction or apply a UI change.
3. Compare the current screen against the baseline.
4. Review a summarized diff plus generated artifacts.
Hubert Gancarczyk