browser-screenshot-diff
Visual + DOM diff between two recorded sessions at matching trajectory step ids; used for visual regression and replay verification
How do I install this agent skill?
npx skills add https://github.com/ruvnet/ruflo --skill browser-screenshot-diffIs this agent skill safe to install?
- Gen Agent Trust Hubpass
The skill is functional and handles local browser session differentiation, but presents a low security risk due to an inherent surface for indirect prompt injection when parsing external webpage DOM content and trajectory files.
- Socketpass
No alerts
- Snykwarn
Risk: MEDIUM · 1 issue
What does this agent skill do?
Browser Screenshot Diff
Compare two recorded sessions step-by-step. Pairs each step in session A to the same step-id in session B, diffs the captured screenshot and accessibility snapshot, reports the first divergence and an aggregate similarity score.
When to use
- Visual regression after a UI change (record before, record after, diff).
- Verifying a
browser-replayrun matches the parent session within tolerance. - Comparing two A/B variants of the same form flow.
Steps
- Locate both RVF containers:
npx -y ruvector@0.2.25 rvf status <session-id-a>.rvf npx -y ruvector@0.2.25 rvf status <session-id-b>.rvf - Load both trajectories from
trajectory.ndjson. Build astep-id → (screenshot_path, snapshot_path)map for each. - Pair steps by
step-id. Steps that exist on only one side are flagged asunmatchedand contribute to the divergence score. - Pixel diff (
--mode pixel|both): compare the two PNGs at each step. Reportmse,psnr, and the bounding box of the largest diff cluster. Threshold default0.02(2% of pixels). - DOM diff (
--mode dom|both): compare the accessibility snapshots node-by-node. Report added / removed / changed nodes with their accessible names. - Aggregate similarity: weighted average across matched steps, weighted by step duration. Verdict goes into a new
findings.mdunder a fresh RVF container so the diff itself is replayable. - Persist the diff verdict in
browser-sessionsunder both source ids' tags so future searches surface "ran a diff against session X".
Caveats
- Pixel diff is sensitive to font hinting, antialiasing, and scrollbar position. Keep viewport pinned across both sessions.
- DOM diff over Playwright's accessibility tree is more stable than HTML diff. Prefer it.
- This skill does not handle dynamic content (clocks, ads); add ignore regions to the field map or pre-process snapshots before diffing.
- The
browser_screenshot_diffMCP tool is not planned (ADR-0001 §7); the skill operates against locally-saved RVF artifacts and usesbrowser_evalonly for live verification.
How can the creator link this skill?
Add the canonical catalog link to the repository README so users can inspect current installs and available audits. The publishing guide covers the complete discovery path.
<a href="https://skillzs.dev/skills/ruvnet/ruflo/browser-screenshot-diff">View browser-screenshot-diff on skillZs</a>