Browser Screenshot Diff
Visual + DOM diff between two recorded sessions at matching trajectory step ids; used for visual regression and replay verification
Install
$ agentstack add skill-kunanonj-ai-skills-hub-browser-screenshot-diff ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-kunanonj-ai-skills-hub-browser-screenshot-diff) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
We're building live execution health for every listing: tool-call success rate, median latency, uptime, and last-checked timestamps, measured, not self-reported. It isn't live yet, so we don't show numbers we can't stand behind.
How agent discovery & health will work →About
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:
``bash npx -y ruvector@0.2.25 rvf status .rvf npx -y ruvector@0.2.25 rvf status .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.
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: KunanonJ
- Source: KunanonJ/ai-skills-hub
- License: MIT
Install and usage instructions live in the source repository linked above.
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Versions
- v0.1.0 Imported from the upstream source.