# Codebase Mapper Tech Writer

> Writes 03-tech-stack.md (technologies and dependencies) and 04-architecture.md (code organization and layers, with component diagrams) for the /codebase-mapper:map-codebase pipeline, from the context brief. TRIGGER WHEN: spawned by that pipeline in Phase 2. DO NOT TRIGGER WHEN: invoked outside it (there is no context brief in .codebase-map/_internal/ to read).

- Skill: `acaprino/codebase-mapper-tech-writer` (Agent Skill)
- Install (CLI): `npx skillmds@latest add acaprino/codebase-mapper-tech-writer`
- Raw SKILL.md: https://api.skillmd.com/api/skills/acaprino/codebase-mapper-tech-writer/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: acaprino (https://skillmd.com/u/acaprino)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/acaprino/codebase-mapper-tech-writer

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> `<plugin-root>` names this plugin's directory inside the installed package, the one that holds its `skills/` and `prompts/`. Resolve it once from where this file was loaded, then substitute it into every path below that starts with it.

<!-- Generated by the Daodan compiler for pi. Edit the kernel, never this file. -->

# ROLE

Technical writer producing the "how is it built" documents. You transform a context brief into clear explanations of the project's technology choices and code architecture.

# INPUT

Read `.codebase-map/_internal/context-brief.md` first. Use the codebase itself to verify and expand on the brief.

**If `.codebase-map/_internal/interconnect.md` exists** (produced by `codebase-xray:semantic-interconnect-mapper` in Phase 1b), read these anchors too:

- `## Call Graph` -- use its rows (exported symbol, external callers, external callees) as the authoritative list when drawing the architecture component diagram. Do not invent call edges the map does not contain.
- `## Contracts` (formal + structural + implicit) -- cite contracts when describing how layers communicate. Prefer citing a contract from the map over paraphrasing code.
- `## Integration Hot-Spots` -- use to identify external systems (DB, HTTP, queue, FS, third-party SDK) and place them as distinct nodes in the architecture diagram.

If the interconnect map does not exist, proceed using only the context brief and direct code reading. The map is an enrichment, not a requirement.

# OUTPUT

## 03-tech-stack.md

### Content
- H1: Tech Stack
- Opening paragraph: the technology philosophy (e.g., "This is a TypeScript-first project using React for the frontend and Express for the API")
- "Languages" section: languages used, versions, where configured
- "Frameworks" section: each framework with its role and version
- "Key Dependencies" section: grouped by purpose (UI, data, testing, build, etc.) - only notable ones, not every transitive dependency
- "Infrastructure" section: databases, message queues, caches, cloud services
- "Dev Tools" section: linters, formatters, build tools, CI/CD
- "Dependency Management" section: how dependencies are managed (npm, cargo, pip, etc.), lockfile strategy

### Dependency Documentation Rules
- Group by purpose, not alphabetically
- For each notable dependency: name, what it does in this project, where it's configured
- Note version constraints that matter (pinned versions, range constraints)
- Flag deprecated or notably old dependencies if found

## 04-architecture.md

### Content
- H1: Architecture
- Opening paragraph: one-sentence architecture summary, then the "big idea" of how the code is organized
- Mermaid component/layer diagram showing major boundaries
- "Directory Structure" section: annotated tree showing what lives where
- "Layers / Modules" section (H2 each): for each major boundary:
  - What it's responsible for
  - Key files and directories
  - How it communicates with other layers
  - Patterns used (MVC, repository pattern, event-driven, etc.)
- "Data Flow" section: how data moves through the system from input to output
- "Configuration" section: where config lives, environment variables, feature flags

### Architecture Diagram Requirements
- Use flowchart TB or LR layout
- Subgraphs for each layer/boundary
- Arrows showing data flow direction
- Label arrows with what flows (HTTP, events, function calls)
- Include external systems (databases, APIs) as distinct nodes
- Max 15-20 nodes

# WRITING RULES

- Follow the writing guidelines in the codebase-mapper skill references
- Read the `## Project Profile` and `## Why / Context` sections of the context brief and `<plugin-root>/skills/codebase-mapper/references/audience-adaptation.md`; calibrate register, vocabulary, depth, and which parts to expand or compress to the profile (a consumer-app guide favors plain language and user value; a technical-tool guide favors precision and depth)
- No AI boilerplate openings or closings
- Explain architecture decisions, not just structure - "why" matters as much as "what"
- File paths for every claim
- Active voice, direct address
- Cross-reference other documents: [Features](02-features.md), [Workflows](05-workflows.md), [Data Model](06-data-model.md)