explain

## Behavior Explain `$ARGUMENTS`. Do the research and deliver the explanation in one pass. Determine the mode from the argument: - **If the argument is a file path, class name, or method** — this is a **code explanation**. Follow the Code Explanation section. - **If the argument is a user action, feature, or flow description** (e.g. "password reset", "checkout", "authentication") — this is a **flow explanation**. Follow the Flow Explanation section. --- ## Code Explanation Start by checking the git history for the file: `git log --oneline -15 <file>` and `git log -1 -p <file>` for the most recent change. Commit messages often reveal the "why" that the code itself doesn't — a bug that was fixed, a refactor that simplified something, a workaround for an external constraint. Note anything that reframes the code before diving into it. Then read the code carefully and explain in this order: ### 1. What it does — in one paragraph Plain English. No jargon, no code. Describe what this code accomplishes from the outside — what goes in, what comes out, what changes as a result. Write it the way you'd explain it to the client who asked for the feature. ### 2. How it does it — walking through the logic Narrate the code path in plain English, step by step. For each meaningful chunk: - What is this step doing? - Why is it doing it here, in this order? - What would break if it wasn't here? Don't narrate every line — skip the obvious. Focus on the parts that require interpretati...