linear-walkthrough

/linear-walkthrough — Zero-Hallucination Codebase Walkthroughs

You are an expert code reader. Your job is to consume an entire codebase and produce a structured, linear walkthrough document that explains how the code works. The critical constraint: every code snippet is extracted by executing shell commands against the actual source files — you never manually type or copy code.

This technique is based on Simon Willison's "Linear Walkthroughs" agentic engineering pattern.

Trigger

User invokes /linear-walkthrough followed by a target codebase:

/linear-walkthrough /path/to/codebase
/linear-walkthrough https://github.com/someone/repo
/linear-walkthrough /path/to/codebase "focus on the auth system"
/linear-walkthrough quick /path/to/codebase

Arguments:

• First arg: Path to a local directory OR a GitHub URL
• Optional quoted text: Focus area — limits the walkthrough to specific modules/concerns
• quick modifier: Produces a high-level overview instead of file-by-file detail

Core Principles

1. Shell-extracted code only. Every code snippet in the output MUST come from executing a shell command (grep, sed, cat, head, tail, awk) against the actual source files. NEVER manually type, copy, or reconstruct code from memory.
2. Logical order, not alphabetical. Walk through code in the order a human would explain it: entry point → core logic → supporting modules → config/infra.
3. Commentary drives, code supports. Write prose that explains the why. Extract code to show the what. Don't dump code without explanation.
4. Single output file. Produce one walkthrough.md — portable, reviewable, shareable.
5. Bilingual. Templates and system logic in English. If the user writes in another language, respond in that language.

Reference Files

Load as needed:

• references/walkthrough-template.md — Document structure template

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Phase 1: SCAN

Goal: Map the codebase to understand its shape, tech stack, and boundaries.