Visually compare two web pages to detect differences. Use this to verify that a code change didn't break the UI, compare staging vs production, or check if a page changed. Captures both pages as screenshots, runs pixel-level comparison, and returns a diff percentage plus a highlighted diff image showing exactly what changed. This is the primary tool — use it whenever you need to verify visual output.

Two modes:

1. Ad-hoc compare: pass before + after URLs.

2. Baseline compare: pass after URL + project (slug or ID) + page_name. Compares against the last-accepted baseline for that page on the project's default branch. Use this when the user has set up a SnapDiff project and you want to verify a page still matches its approved state.

Take a screenshot of a web page. Use this when you need to see what a webpage looks like right now — to inspect layout, verify rendering, or capture a baseline for later comparison.

Capture the current state of a page as the visual baseline for a SnapDiff project. Call this once per page before using snapdiff_verify_ui_change — the baseline is the reference screenshot that all future verifications diff against.

For localhost URLs, the page is captured locally with a headless browser (no tunnel needed). For public URLs, the SnapDiff backend captures it. Returns when the baseline is confirmed in place.

Capture every page in the list and diff them all against their baselines in one build. Use this after editing a shared component or design token to check whether the change affected pages you did not directly modify.

Returns a per-page summary of changed vs unchanged. If any page changed, a review URL is included so a human can approve or reject before the baseline moves.

Verify a UI change you just made matches what you intended. Use this whenever you modify a route, page, or component and need to confirm the visual result.

Returns a verdict (pass, expected_change_detected, unexpected_regression, no_change_detected, or needs_human_review), a next_action, and a review_url. Always surface review_url to the user — it is the human-reviewable dashboard page showing the before/after/diff. Do not share raw image URLs (diff_url, before_url, after_url) — those are internal references.

Requires a SnapDiff project + page baseline. Pass intent to describe in one sentence what you meant to change. For sharper verdicts, pass intent_regions with either a CSS selector (recommended for code-editing agents — SnapDiff resolves it to a bbox during capture) or a bbox directly (when your agent drives a browser and already knows pixel coordinates).

Render HTML/CSS directly to an image. Use this to generate social cards, OG images, email headers, or any visual from code without needing a hosted URL.