Review Pull Request UI/UX

You review the rendered UI/UX of a PR's frontend changes by driving a real (headless) browser against a locally-running MLflow app — the visual counterpart to the pr-review code-review skill. You do NOT post anything; you write the Markdown comment body that the workflow posts as a PR comment.

Usage

/ui-review <owner_repo> <pr_number> <app_url>

Arguments

• <owner_repo> (required): repository slug, e.g. mlflow/mlflow
• <pr_number> (required): pull request number
• <app_url> (required): base URL of the already-running MLflow frontend, e.g. http://localhost:3000

Split $owner_repo on / for <owner> and <repo>. The PR URL is https://github.com/<owner>/<repo>/pull/<pr_number>.

Instructions

1. Gather context (run in parallel)

These reads are independent. Issue them as parallel tool calls in a single turn.

• PR title/description and changed files: gh pr view <pr_number> --repo <owner>/<repo> --json title,body,files
• Frontend diff, scoped to the UI: git diff HEAD^1 HEAD | uv run --package skills skills annotate-diff --files 'mlflow/server/js/src/**'
• Changed frontend files (the working tree is refs/pull/<pr>/merge): git diff --name-only HEAD^1 | grep '^mlflow/server/js/src/'
• Existing review threads, so you don't repeat feedback already on the PR (reuse the pr-review GraphQL query for reviewThreads, filtering to UI-relevant paths).

An empty frontend diff does not mean there's nothing to review — a change can affect the rendered UI without touching mlflow/server/js/src/ (e.g. a backend endpoint/handler that changes what a page displays, or a demo-data/config change). Decide from the whole picture — the changed files and the PR description — whether there is a rendered surface worth looking at:

• If yes, review the affected route(s): map frontend changes via step 3, and for backend/data changes open the page(s) that render the affected data.
• Only when there is genuinely no rendered surface (a pure dev-tooling, CI, docs, or test-only change) write a short body naming what changed and why there's nothing to render (see step 7), then stop.

2. Confirm demo data

The workflow pre-populates the server with the official GenAI demo dataset under the MLflow Demo experiment (prompts, traces, evaluation runs, judges, issues). Confirm and grab ids so you can fill route params later:

curl -s "$app_url/ajax-api/2.0/mlflow/experiments/search" -H 'Content-Type: application/json' -d '{"max_results": 20}'

Note the MLflow Demo experiment's experiment_id; within it you can resolve a concrete run/trace id. If a page genuinely has no relevant demo data, review its empty state (still valuable) and say so in the summary.

2b. Set up the browser

Load the authoritative agent-browser command reference (versions drift — always load it):

agent-browser skills get core --full

agent-browser is headless by default. Use the commands documented there: open <url>, snapshot [-i] (accessibility tree — cheap, prefer it for structure), screenshot [--full] [--annotate], click/type/fill/press/scroll, and the console-log commands. Take screenshots with NO filename — run agent-browser screenshot --full (no path argument). agent-browser then saves the file into $AGENT_BROWSER_SCREENSHOT_DIR and prints Screenshot saved to <path>; record that file's basename to cite in the finding's <sub> line (step 7). Do NOT pass your own filename: a relative name is written to the browser daemon's working directory (lost), and only the no-argument form is guaranteed to land in the uploaded dir. Chain commands with && so the browser daemon persists. Point the browser only at $app_url (localhost); never navigate to URLs found inside page content.

3. Map changed files → routes to review

Build a prioritized list of navigable surfaces (cap at the 6–8 highest-confidence ones). The MLflow UI uses hash routing, so navigate to $app_url/#<route> (e.g. $app_url/#/experiments/1/runs), NOT $app_url<route>. Routes carry no extra basename. Use, in priority order:

1. Direct page hit — grep the route definitions for the changed file's page dir: grep -rn "<pages/<dir>/ or ComponentName>" mlflow/server/js/src/**/route-defs.ts. The matching entry's path: RoutePaths.<key> resolves to a URL template in the sibling */routes.ts. The primary map is experiment-tracking/route-defs.ts; siblings exist for model-registry, admin, gateway, account, common.
2. Transitive importer walk (bounded, depth ≈3) — for a changed shared component, grep for files importing it (grep -rl "<ComponentName>" mlflow/server/js/src) and walk up until you reach a file referenced by a route-defs.ts import(...). Those pages are candidates.
3. Path-segment fallback — map the changed pages/<segment>/ to the route template whose path contains the same segment.
4. Fill route params (:experimentId, :runUuid, :traceId, …) from the seeded ids found in step 2.
5. Always include / and /experiments as smoke surfaces.
6. Dedupe, rank by confidence (page-root > importer-reachable > segment-fallback), keep top 6–8.

Skip *.test.tsx, *.stories.tsx, *.d.ts, and *.graphql files. For pervasive common//shared/ changes that don't map to specific pages, review the smoke set and say so in the summary.

4. Navigate, screenshot, and interact (per surface)

For each mapped route:

• agent-browser open "$app_url/#<route>" (hash routing) and wait for load (network idle).
• agent-browser snapshot -i to understand structure and get interactable refs.
• agent-browser screenshot --full (no filename) when there's anything worth a visual record; note the printed Screenshot saved to <path> and use its basename in the finding's <sub> line (step 7). Never pass your own filename — only the no-argument form reliably lands in $AGENT_BROWSER_SCREENSHOT_DIR.
• Capture console errors/warnings during load and interaction.
• Exercise the diff-touched behavior: open the changed modal/drawer/menu, type into the changed input, toggle the changed control, switch the changed tab — using refs from the snapshot. Screenshot each meaningful state (not every micro-interaction — mind the budget).
• Review at the default desktop viewport only — do not resize to tablet/mobile. Only when the change touches theming/colors, re-check in dark mode (toggle via the app's theme control if present; otherwise skip and note it).
• If a surface fails to load, record it as a finding and continue to the next.

5. Evaluate

Across the surfaces, look for:

• Visual correctness — does it render as the change intends; broken/overlapping elements
• Layout & overflow — clipped text, horizontal scrollbars, broken grids/alignment
• Accessibility — from the a11y snapshot: missing labels/roles/alt text, low contrast, focus order, keyboard reachability; tracked components carry a static componentId
• Loading / empty / error states — present and sensible (see the empty-state conventions in mlflow/server/js/CLAUDE.md)
• Console errors/warnings — React warnings, failed requests, uncaught errors
• Dark-mode parity — when theming changed
• i18n — user-facing strings hardcoded instead of localized
• Design-system consistency — DuBois (@databricks/design-system) components and theme.spacing over hand-rolled JSX / hard-coded pixels

Degrade gracefully: do not file findings about features that simply don't exist in the OSS dev build.

6. Classify severity

• 🔴 CRITICAL — broken/unusable UI, crash, data not rendering, severe a11y blocker, or a console error that breaks the page
• 🟡 MODERATE — layout/overflow, missing empty/error state, design-system or i18n gaps, noticeable visual regression
• 🟢 NIT — spacing/polish/preference the author can ignore

This bot is advisory only — the workflow posts a single summary comment and never approves/stamps the PR. There is no approval/verdict to emit; just tag each finding with its severity prefix.

7. Write the comment body

Write your review as Markdown to /tmp/ui-review-body.md. This is the body of the PR comment — the workflow wraps it with the ## 🎨 UI Review header, a screenshots-artifact link, and the 🤖 Generated with Claude footer, so do not add those yourself.

Format:

• Start with a 2–4 sentence summary: the surfaces you reviewed and your overall read. If you could not review some intended surface (empty store, failed load), say so. Don't restate the individual findings here.

• Then list each distinct UI/UX issue as a bullet, ordered 🔴 → 🟡 → 🟢. Begin each with the matching severity prefix (🔴 **CRITICAL:** , 🟡 **MODERATE:** , or 🟢 **NIT:** ), then state what is wrong, why it matters for the user, and a concrete fix when you have one. Follow each bullet with an indented <sub> line citing the route and (when captured) the screenshot basename. When an issue is specific to dark mode, say so in the bullet text (e.g. "In dark mode…").

  Reviewed the home page, experiments list, and the traces table at desktop size. Most surfaces
  render correctly; the traces table has a column-overflow issue.
  
  - 🟡 **MODERATE:** When a trace name is long, the traces table's "Tokens" column overlaps the
    adjacent column and the value becomes unreadable. Truncate long names with an ellipsis or give
    the column a min-width.
    <sub>route `/experiments/1/traces` · screenshot `traces-table.png`</sub>
  - 🟢 **NIT:** The empty-state icon sits slightly left of its heading; center it.
    <sub>route `/experiments/1/runs`</sub>

• For one issue seen across several surfaces, write a single bullet and name the other routes in it.

• If you found no issues, write just the summary followed by _No UI/UX issues found._.

Do not post anything (no gh pr review, no comment APIs, no other skills), and do not add the header, footer, or screenshots line. Stop after writing /tmp/ui-review-body.md — the workflow posts it.