tomsej PR Explain
Generate an accurate English explanation of one PR. Read the repository; never modify it.
Read the PR
Input: PR number or URL.
- Metadata:
gh pr view <n> --json title,body,baseRefName,headRefOid,url. - Changes and evidence:
gh pr diff <n>andgh pr checks <n>. - Fetch without checkout:
git fetch origin pull/<n>/head; inspect files withgit show FETCH_HEAD:<path>. - Read callers and surrounding code, not only the diff.
- Treat PR claims as claims: confirm each with code, tests, or CI; mark unsupported claims ⚠️.
Write the explanation
Save ~/Workspace/specs/<project>/pr-<n>-<slug>/explanation.md; derive project, number, and slug—never guess them.
Use these sections in order:
- Background — optional newcomer context, then the specific problem.
- Intuition — the core idea with small example data.
- Change top to bottom — one causal architecture/code walkthrough.
- Claims and evidence — claim, user-visible result, exact test/check evidence.
- Try it yourself — disposable setup and observable checklist items
- [ ]. - Quiz — five useful multiple-choice questions.
Change map
Use closed <details> blocks: <code>PRINCIPLE</code> → <code>FLOW</code> → <code>STEP</code> → <code>KEPT</code> → <code>VERIFY</code>.
Each <summary> must stand alone: label, short title, one-sentence conclusion.
Inside STEP, include only important files: 🟡 <a href="<diff-url>"><code>MODIFIED</code></a> or 🟢 <a href="<diff-url>"><code>NEW</code></a>.
Make the file name a permalink to exact HEAD lines: .../blob/<sha>/<path>#Lx-Ly.
Show a short final-code snippet fenced with the language of the source file; link to the diff instead of pasting raw diff headers.
Skip lockfiles, generated files, mechanical edits, and repeated prose.
Format
Write Markdown only. Use small mermaid diagrams with example data; no ASCII diagrams.
Use exact symbol, test, and file names. Unknown facts are — or ⚠️, never inventions.
Quiz answers must render inside raw HTML: <details><summary>Answer</summary><p><strong>B.</strong> Why it is right and the others are wrong.</p></details>.
Print the absolute output path.
Share
Create and print the Plannotator URL; do not start a local server:
SHARE_URL="$(node -e 'const fs=require("node:fs"),z=require("node:zlib");const p=fs.readFileSync(process.argv[1],"utf8");console.log("https://share.plannotator.ai/#"+z.deflateRawSync(JSON.stringify({p,a:[]})).toString("base64url"))' "$EXPLANATION_PATH")"; printf 'Plannotator: %s\n' "$SHARE_URL"
The hash contains compressed, unencrypted content. Do not create it for sensitive PRs.