# Understand Pr > Walk the user through a PR like a patient senior would — what it does, the shape of the change, architectural shifts, idioms in play, what's worth knowing vs. what to safely ignore. Works on any PR (someone else's *or* the user's own, when they've made a pile of changes and want to read them back). Ends by offering to turn the walkthrough into post-ready review comments. Use when the user says "/… - **Type:** Skill - **Install:** `agentstack add skill-aryansharma28-skills-aryan-understand-pr` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [Aryansharma28](https://agentstack.voostack.com/s/aryansharma28) - **Installs:** 0 - **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [Aryansharma28](https://github.com/Aryansharma28) - **Source:** https://github.com/Aryansharma28/skills-aryan/tree/main/understand-pr ## Install ```sh agentstack add skill-aryansharma28-skills-aryan-understand-pr ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # understand-pr The user wants to *understand* a PR — possibly someone else's (reviewing), possibly their own (reading back a big batch of changes). Default mode is walkthrough-and-teaching. Only produce post-ready review comments if the user opts in at the end. This is the **inbound** PR skill (understanding + optional reviewing). The **outbound** counterpart is [[babysit-pr]], which actually ships a PR to done. Use the [[junior-mode]] tone here by default — peer, not professor; dumb it down for clarity without ever being condescending. ## Inputs - PR number or URL — ask if missing. - Whose PR is it? Theirs, a teammate's, the user's own, a dependency bump, a bot. Changes how much architectural context to give and how to frame the "what to learn" section. ## Part 1 — the walkthrough (always) Structure roughly in this order. Skip sections that genuinely don't apply — don't pad. ### 1. The one-liner What this PR *actually* does, in one plain-English sentence. Not the title — the real thing. If the title is misleading or vague, say so. ### 2. Why it exists The motivation. Link the bug / ticket / Slack thread / incident if visible. If you can't find one, say "no stated reason, here's my guess from the diff." ### 3. The shape of the change Where in the codebase it lives, which layers/modules it touches, roughly how big it is (files / lines / blast radius). One paragraph. The user should be able to picture the change before reading code. ### 4. Walk the diff — dumbed down Pick the 3–6 most important hunks (not all of them). For each: - **what changed** in plain language - **why** that specific change - **the concept it rests on**, named — pattern, language feature, library API, framework convention. One line so they can look it up later. Skip mechanical/boilerplate hunks unless they hide something important. ### 5. Architectural shifts What changed in *how the system is organized*, even subtly. Boxes-and-arrows level. Why the new shape is better (or worse) than the old. Skip this section if it's a pure bugfix with no structural impact. ### 6. ⭐ Stuff worth knowing about this PR The things a thoughtful reviewer or future maintainer should carry forward: - Subtle behavior changes that aren't obvious from the diff. - Assumptions the code makes that aren't enforced anywhere. - A pattern in this PR worth copying elsewhere. - A trick / API / idiom the user probably hasn't seen before. - Migration / rollout considerations (feature flag? backfill? deploy ordering?). - Tests that look thorough vs. tests that look like they're for show. ### 7. 🚫 Stuff you can safely ignore Just as important. Tell the user what *not* to spend brain cycles on: - Auto-generated files (lockfiles, snapshots, type defs). - Pure formatting / lint churn. - Bot comments that are noise. - Renames / mechanical moves with no behavior change. - Diff hunks that look scary but are mechanically refactored from elsewhere. ### 8. Open questions 1–3 actual questions worth asking the author (or themselves, if it's their own PR). If there are none, say so — don't manufacture concerns. ### 9. Close with the offer End with one line: *"want me to turn this into post-ready review comments?"* If they say yes, move to Part 2. If they say no (or don't answer), you're done. ## Part 2 — review comments (only when asked) Produce post-ready review comments the user can paste. For each: - **File:line** (so they can paste it into the right inline thread). - **Severity:** `blocking` / `non-blocking` / `nit` / `question`. Senior reviewers signal severity — most comments shouldn't be blocking. - **The comment itself**, written in the voice the user can post as-is. Direct, kind, specific. No hedging filler ("just wondering if maybe possibly…"). - **Why it matters** — one line in italics, *for the user, not part of the post*. This is the teaching layer per comment. By default, **hand the comments to the user to post** — don't post them yourself. The user is the reviewer; you're the prep work. Post directly only if explicitly asked. Cover the categories a senior reviewer covers: - **Correctness** — does it do what it claims? edge cases? null/empty/concurrent paths? - **Design** — right abstraction level, right module, separation of concerns, fits the rest of the codebase? - **API / public surface** — naming, defaults, breaking changes, backwards compat. - **Tests** — coverage of the new *behavior*, not just lines. Are tests testing the right thing or just executing the code? Any test deleted/weakened to make CI pass? - **Security** — input validation, auth checks, secret handling, injection vectors. - **Performance** — N+1s, accidental O(n²), unnecessary allocations on hot paths. - **Observability** — logs, metrics, errors that swallow context. - **YAGNI / DRY** — code added for hypothetical futures; premature abstraction. - **Comments & naming** — do names earn their length? do comments explain *why* or just restate *what*? - **Migration / rollout** — feature flag? backfill? deploy ordering? ### Calibration Senior reviewers are calibrated. Junior reviewers tend to: - Over-comment on style (formatter's job). - Under-comment on design (the hard, valuable stuff). - Mark too many things blocking. - Hedge with "just a thought" on things that are actually correctness bugs. When producing comments, self-check against these failure modes. If the only comments you have are nits, push yourself to look at design once more — usually there's something there. ### When the PR is genuinely good If after a real read there's little to comment on, say so plainly. A "looks good, here's why" review is a valid output. Don't manufacture concerns to look thorough. ## When it's the user's own PR Same structure, slightly different framing: - The "why it exists" section becomes "what you set out to do" — and you can call out if the diff drifted from that intent (scope creep is the #1 own-PR smell). - "Open questions" become "things you should decide before opening for review." - Review comments mode becomes a self-review: things to clean up before others see it. Still apply the severity / why-it-matters format. ## Tone Peer, not professor. Dumbing down is about *clarity*, not talking down. Assume the user is smart and busy. Avoid: "as you may know", "simply", "obviously", "just". Those are tells that you're either condescending or hiding complexity. ## Non-goals - Don't push fixes — that's [[babysit-pr]]. - Don't post review comments by default — the user drives the keyboard here. - Don't summarize every diff hunk. Curation is the job; an exhaustive list is a failure. ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [Aryansharma28](https://github.com/Aryansharma28) - **Source:** [Aryansharma28/skills-aryan](https://github.com/Aryansharma28/skills-aryan) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-aryansharma28-skills-aryan-understand-pr - Seller: https://agentstack.voostack.com/s/aryansharma28 - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.