codebase-mapping

A codebase documentation skill that maps how an unfamiliar software project is organised and works. It records the architecture, coding conventions, dependencies, files, and entry points in structured documents.

In plain words
What is it for?
Use it when joining a new codebase, before a feature that crosses several modules, or when the existing project map is missing or outdated.
Why use it?
It saves an agent from repeatedly scanning the whole repository before making changes. The resulting map gives future work a shared reference for how the project fits together.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/dvnghiem/flowdeck/codebase-mapping
Any agent
npx skills add DVNghiem/FlowDeck --skill codebase-mapping
Clone the repo
git clone --depth 1 https://github.com/DVNghiem/FlowDeck

Made for: Claude Code, Codex.

Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 677 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00036 $0.00677
Opus 5 $0.00018 $0.00338
Sonnet 5 $0.00007 $0.00135
Haiku 4.5 $0.00004 $0.00068

Measured 2d ago against content hash 704bac990f4a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-mapping scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

src/skills/codebase-mapping/SKILL.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codebase Mapping Skill

Produces structured documentation of a codebase that agents can read to answer "how does this project work?" without re-scanning every time.

When to Activate

  • Starting work on an unfamiliar codebase
  • Before a major feature that spans multiple modules
  • When /fd-task runs its init step for an unmapped project
  • When ~/.fd-plan/<slug>/.codebase/ is missing or stale

Output Files

All outputs go to ~/.fd-plan/<slug>/.codebase/:

File Contents
ARCHITECTURE.md System design: layers, modules, data flow
CONVENTIONS.md Naming, style, patterns specific to this project
DEPENDENCIES.md Key external packages and what they do
INDEX.md File-by-file inventory
ENTRY_POINTS.md How the application starts and key entry files

Mapping Sequence

Step 1: Start from the outside

Read in this order:

  1. package.json / pyproject.toml / Cargo.toml — dependencies, scripts, metadata
  2. README.md — stated purpose and architecture
  3. Entry point files (main, index, app, server)
  4. Configuration files (env examples, config schemas)

Step 2: Map the directory structure

Document each top-level directory's purpose:

src/
  api/          — HTTP route handlers
  services/     — Business logic
  models/       — Database schemas and queries
  utils/        — Shared helpers
tests/          — Test files (mirror of src/)
scripts/        — Build and deployment scripts

Do not guess. Read the files to confirm what each directory contains.

Step 3: Document key conventions

Find examples in the code:

  • How are errors handled? (throw? return Result? error callback?)
  • How are modules exported? (default export? named exports?)
  • What is the naming pattern for files? (UserService.ts? user-service.ts?)
  • Where do interfaces/types live?
  • How is dependency injection done?

Write 1-2 examples for each pattern, not a generic description.

Step 4: Document entry points

## Entry Points

- `src/index.ts` — Application bootstrap, registers routes and middleware
- `src/workers/queue.ts` — Background job processor, runs independently
- `scripts/migrate.ts` — Database migration runner

Read the full file on GitHub · 88 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 88 lines · 36 tokens per session scan A 704bac990f4a

Subscribe to this mod's changes

codebase-mapping is a skill published in the GitHub repository DVNghiem/FlowDeck (24 stars, last pushed 13d ago), licensed MIT. It adds 36 tokens to every session and 677 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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