/code-tour

name: "code-tour"
description: "Use when asked for a CodeTour .tour file or a step-by-step code walkthrough (onboarding, architecture, PR review, how X works). Writes persona-targeted steps that link to real files and line numbers, checked to exist."

Code Tour

Create **CodeTour** files — persona-targeted, step-by-step walkthroughs of a codebase that link directly to files and line numbers. CodeTour files live in `.tours/` and work with the [VS Code CodeTour extension](https://github.com/microsoft/codetour).

Overview

A great tour is a **narrative** — a story told to a specific person about what matters, why it matters, and what to do next. Only create `.tour` JSON files. Never modify source code.

When to Use This Skill

• User asks to create a code tour, onboarding tour, or architecture walkthrough
• User says "tour for this PR", "explain how X works", "vibe check", "RCA tour"
• User wants a contributor guide, security review, or bug investigation walkthrough
• Any request for a structured walkthrough with file/line anchors

Core Workflow

1. Discover the repo

Before asking anything, explore the codebase:

In parallel: list root directory, read README, check config files. Then: identify language(s), framework(s), project purpose. Map folder structure 1-2 levels deep. Find entry points — every path in the tour must be real.

If the repo has fewer than 5 source files, create a quick-depth tour regardless of persona — there's not enough to warrant a deep one.

2. Infer the intent

One message should be enough. Infer persona, depth, and focus silently.

| User says | Persona | Depth | |-----------|---------|-------| | "tour for this PR" | pr-reviewer | standard | | "why did X break" / "RCA" | rca-investigator | standard | | "onboarding" / "new joiner" | new-joiner | standard | | "quick tour" / "vibe check" | vibecoder | quick | | "architecture" | architect | deep | | "security" / "auth review" | security-reviewer | standard | | (no qualifier) | new-joiner | standard |

When intent is ambiguous, default to **new-joiner** persona at **standard** depth — it's the most generally useful.

3. Read actual files

**Every file path and line number must be verified.** A tour pointing to the wrong line is worse than no tour.

4. Write the tour

Save to `.tours/<persona>-<focus>.tour`.

{
  "$schema": "https://aka.ms/codetour-schema",
  "title": "Descriptive Title — Persona / Goal",
  "description": "Who this is for and what they'll understand after.",
  "ref": "<current-branch-or-commit>",
  "steps": []
}

Step types

| Type | When to use | Example | |------|-------------|---------| | **Content** | Intro/closing only (max 2) | `{ "title": "Welcome", "description": "..." }` | | **Directory** | Orient to a module | `{ "directory": "src/services", "title": "..." }` | | **File + line** | The workhorse | `{ "file": "src/auth.ts", "line": 42, "title": "..." }` | | **Selection** | Highlight a code block | `{ "file": "...", "selection": {...}, "title": "..." }` | | **Pattern** | Regex match (volatile files) | `{ "file": "...", "pattern": "class App", "title": "..." }` | | **URI** | Link to PR, issue, doc | `{ "uri": "https://...", "title": "..." }` |

Step count

| Depth | Steps | Use for | |-------|-------|---------| | Quick | 5-8 | Vibecoder, fast exploration | | Standard | 9-13 | Most personas | | Deep | 14-18 | Architect, RCA |

Writing descriptions — SMIG formula

• **S — Situation**: What is the reader looking at?
• **M — Mechanism**: How does this code work?
• **I — Implication**: Why does this matter for this persona?
• **G — Gotcha**: What would a smart person get wrong?

5. Validate

• [ ] Every `file` path relative to repo root (no leading `/` or `./`)
• [ ] Every `file` confirmed to exist
• [ ] Every `line` verified by reading the file
• [ ] First step has `file` or `directory` anchor
• [ ] At most 2 content-only steps
• [ ] `nextTour` matches another tour's `title` exactly if set

Personas

| Persona | Goal | Must cover | |---------|------|------------| | **Vibecoder** | Get the vibe fast | Entry point, main modules. Max 8 steps. | | **New joiner** | Structured ramp-up | Directories, setup, business context | | **Bug fixer** | Root cause fast | Trigger -> fault points -> tests | | **RCA investigator** | Why did it fail | Causality chain, observability anchors | | **Feature explainer** | End-to-end | UI -> API -> backend -> storage | | **PR reviewer** | Review correctly | Change story, invariants, risky areas | | **Architect** | Shape and rationale | Boundaries, tradeoffs, extension points | | **Security reviewer** | Trust boundaries | Auth flow, validation, secret handling | | **Refactorer** | Safe restructuring | Seams, hidden deps, extraction order | | **External contributor** | Contribute safely | Safe areas, conventions, landmines |

Narrative Arc

1. **Orientation** — `file` or `directory` step (never content-only first step — blank in VS Code) 2. **High-level map** — 1-3 directory steps showing major modules 3. **Core path** — file/line steps, the heart of the tour 4. **Closing** — what the reader can now do, suggested follow-ups

Anti-Patterns

| Anti-pattern | Fix | |---|---| | **File listing** — "this file contains the models" | Tell a story. Each step depends on the previous. | | **Generic descriptions** | Name the specific pattern unique to this codebase. | | **Line number guessing** | Never write a line you didn't verify by reading. | | **Too many steps** for quick depth | Actually cut steps. | | **Hallucinated files** | If it doesn't exist, skip the step. | | **Recap closing** — "we covered X, Y, Z" | Tell the reader what they can now *do*. | | **Content-only first step** | Anchor step 1 to a file or directory. |

Cross-References

• Related: `engineering/codebase-onboarding` — for broader onboarding beyond tours
• Related: `engineering/pr-review-expert` — for automated PR review workflows
• CodeTour exten