PR Review Canvas
Build a canvas that presents a PR diff reorganized for reviewer comprehension — not in file-tree order.
Prerequisites
Read ~/.cursor/skills-cursor/canvas/SKILL.md first. It contains the generation policy, design guidance, slop rules, self-check, and file-path conventions you must follow. The full component and hook surface is declared in ~/.cursor/skills-cursor/canvas/sdk/index.d.ts and its sibling .d.ts files — read them to discover exact exports and prop shapes rather than guessing.
Gather the diff
Expect a GitHub PR link (a full URL like https://github.com/<owner>/<repo>/pull/<n>, or an equivalent gh-resolvable reference). Use gh pr diff <pr> to collect every file's path, additions, deletions, and hunks.
If the user didn't provide a PR link, stop and ask. Do not guess at the current branch, infer from recent history, or fall back to a local git diff. Ask the user which diff they want to review — a specific PR URL or number — and wait for their reply before continuing.
Group changes for comprehension
Do not present files in alphabetical or tree order. Reorganize into sections ordered by reviewer value:
- Core logic — New behavior, algorithm changes, state transitions, API surface changes. Show full diffs with surrounding context.
- Wiring & integration — Route registration, dependency injection, config plumbing that connects the core logic. Condensed — enough to confirm correctness.
- Boilerplate & mechanical — Import reordering, renames, generated code, formatting, type re-exports. Summarize as a list of file names and stats. No inline diffs unless specifically relevant.
Lead with core logic. The reviewer's attention is freshest at the top.
Distill complex logic into pseudocode
When a core change involves dense or intricate logic — deeply nested conditions, state machines, retry/backoff flows, multi-step transformations — add a short pseudocode summary next to the diff. The pseudocode should strip away language syntax, error handling, and boilerplate to expose the essential algorithm or control flow in a few lines. This lets the reviewer confirm intent before reading the real code.
Only do this when the actual diff is hard to scan. Straightforward changes don't need a pseudocode mirror.
Trace tricky logic on a concrete example
Pseudocode shows the shape of the change; an example trace shows it executing. When a hunk changes behavior in a way that's hard to predict from reading it — reordered effects, new short-circuits, altered edge cases — pick a concrete input and walk it through both the old and new code paths side-by-side, highlighting the step where they diverge and what the observable outcome is. Keep the input small and realistic.
Use this for genuinely surprising behavior changes, not every core hunk.
Call attention to tricky things
When a hunk contains something surprising, risky, or easy to miss, visually separate it from the surrounding diff and pair it with a short tag (e.g. "Subtle", "Breaking", "Race condition", "Perf") and a one-sentence explanation so the reviewer sees the concern and the code together.
Reserve these callouts for genuinely tricky items — overuse destroys signal.
Tone and content
Write reviewer-facing commentary, not a changelog. Focus on:
- Why something changed, not just what changed.
- Interactions between files — e.g. "The new validator in
core.tsis invoked by the route added inroutes.ts." - Anything the diff alone doesn't make obvious.
Keep commentary terse. One or two sentences per note.
Be creative
The sections above are a floor, not a ceiling. The goal is the fastest possible path for the reviewer to understand this specific change — so look at the diff in front of you and ask what representation would actually help. A tiny state diagram, a before/after call graph, a table of input→output pairs, a timeline of commits, a confidence annotation per file, a single large callout with everything else collapsed — whatever fits the change.
The canvas SDK has charts, tables, diff views, DAG layout, cards, stats, interactive state, and more. Reach for whichever components best serve the change at hand. A review of a refactor looks different from a review of a bug fix looks different from a review of a new feature — let the canvas reflect that.
