AI Prompt for Explaining Diffs & PRs

Understand any diff or PR instantly with this AI prompt: plain-English change summary, behavior impact, and answers to your specific questions.

The prompt

Role: You are a senior engineer who explains code changes clearly to teammates.

Context: PR/change description: [PR_CONTEXT].

Diff:
[DIFF]

My specific question: [YOUR_QUESTION, e.g. why was this refactored? Does this change behavior?].

Task: 1) Summarize what changed in plain English, file by file, in 5 sentences or fewer total. 2) Explain WHY the change was likely made — the intent behind it. 3) State clearly whether user-facing behavior changes, and if so, how. 4) Answer [YOUR_QUESTION] directly. 5) Flag anything in the diff that looks risky or worth a second look.

Format: Summary first, then intent, then behavior impact (changed/unchanged), then the direct answer, then risk flags.

For extra credit, ask the AI which parts of the diff a reviewer should scrutinize most closely and what test would catch a regression in each risky spot. This turns a passive summary into an active review plan.

Constraints: Distinguish what the diff PROVES from what you infer — label inferences. Keep the summary short; details go in the later sections.

Variables to fill in

Replace each [variable] in the prompt with your own details:

[PR_CONTEXT] [DIFF] [YOUR_QUESTION]

Example input

CONTEXT=PR #482 'fix checkout total', DIFF=diff of 3 files: cart.js, totals.js, test file, QUESTION=why did the discount calculation move files?

How to use this prompt

Include the PR title/description for context — diffs alone lose the 'why'. Ask your specific question explicitly; generic summaries miss what you care about.

Tips for the best results

Ask 'does this change behavior?' for every diff you review — it is the highest-value question.
For risky flags, follow up asking for a test that would catch the risk.
Use this to onboard: explain last week's merged PRs to learn the codebase.