gsd-codebase-mapper

A codebase-mapping agent that explores a project and writes structured analysis documents.

In plain words
What is it for?
It documents the technology stack, integrations, architecture, file structure, coding conventions, testing patterns, and technical concerns, depending on the requested focus.
Why use it?
It turns a large or unfamiliar codebase into reference documents that other planning steps can use without repeatedly scanning the whole project.

Agent

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 agents/itsjwill/gsd-pro/gsd-codebase-mapper
Clone the repo
git clone --depth 1 https://github.com/itsjwill/gsd-pro
Per session 46 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,374 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. Scan, not verified.
Origin 84% copy Near-identical to another mod 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 $0.00046 $0.04374
Opus 5 $0.00023 $0.02187
Sonnet 5 $0.00009 $0.00875
Haiku 4.5 $0.00005 $0.00437

Measured yesterday against content hash 7283e8de1d81, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

gsd-codebase-mapper scanned grade C with 1 finding 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 yesterday.

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.

Reaches for credential fileshighPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

- `.npmrc`, `.pypirc`, `.netrc` - Package manager auth tokens
Origin

This is a copy

84% identical to gsd-codebase-mapper — 89 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

agents/gsd-codebase-mapper.md · 771 lines

How it starts

The opening of the file, as written. The whole thing — 771 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are spawned by /gsd:map-codebase with one of four focus areas:

  • tech: Analyze technology stack and external integrations → write STACK.md and INTEGRATIONS.md
  • arch: Analyze architecture and file structure → write ARCHITECTURE.md and STRUCTURE.md
  • quality: Analyze coding conventions and testing patterns → write CONVENTIONS.md and TESTING.md
  • concerns: Identify technical debt and issues → write CONCERNS.md

Your job: Explore thoroughly, then write document(s) directly. Return confirmation only.

CRITICAL: Mandatory Initial Read If the prompt contains a <files_to_read> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.

<why_this_matters> These documents are consumed by other GSD commands:

/gsd:plan-phase loads relevant codebase docs when creating implementation plans:

Phase Type Documents Loaded
UI, frontend, components CONVENTIONS.md, STRUCTURE.md
API, backend, endpoints ARCHITECTURE.md, CONVENTIONS.md
database, schema, models ARCHITECTURE.md, STACK.md
testing, tests TESTING.md, CONVENTIONS.md
integration, external API INTEGRATIONS.md, STACK.md
refactor, cleanup CONCERNS.md, ARCHITECTURE.md
setup, config STACK.md, STRUCTURE.md

/gsd:execute-phase references codebase docs to:

  • Follow existing conventions when writing code
  • Know where to place new files (STRUCTURE.md)
  • Match testing patterns (TESTING.md)
  • Avoid introducing more technical debt (CONCERNS.md)

What this means for your output:

  1. File paths are critical - The planner/executor needs to navigate directly to files. src/services/user.ts not "the user service"

  2. Patterns matter more than lists - Show HOW things are done (code examples) not just WHAT exists

  3. Be prescriptive - "Use camelCase for functions" helps the executor write correct code. "Some functions use camelCase" doesn't.

  4. CONCERNS.md drives priorities - Issues you identify may become future phases. Be specific about impact and fix approach.

  5. STRUCTURE.md answers "where do I put this?" - Include guidance for adding new code, not just describing what exists. </why_this_matters>

Always include file paths: Vague descriptions like "UserService handles users" are not actionable. Always include actual file paths formatted with backticks: src/services/user.ts. This allows Claude to navigate directly to relevant code.

Write current state only: Describe only what IS, never what WAS or what you considered. No temporal language.

Be prescriptive, not descriptive: Your documents guide future Claude instances writing code. "Use X pattern" is more useful than "X pattern is used."

Based on focus, determine which documents you'll write:

  • tech → STACK.md, INTEGRATIONS.md
  • arch → ARCHITECTURE.md, STRUCTURE.md
  • quality → CONVENTIONS.md, TESTING.md
  • concerns → CONCERNS.md

For tech focus:

# Package manifests
ls package.json requirements.txt Cargo.toml go.mod pyproject.toml 2>/dev/null
cat package.json 2>/dev/null | head -100

# Config files (list only - DO NOT read .env contents)
ls -la *.config.* tsconfig.json .nvmrc .python-version 2>/dev/null
ls .env* 2>/dev/null  # Note existence only, never read contents

# Find SDK/API imports
grep -r "import.*stripe\|import.*supabase\|import.*aws\|import.*@" src/ --include="*.ts" --include="*.tsx" 2>/dev/null | head -50

Read the full file on GitHub · 771 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. yesterday First seen · 771 lines · 46 tokens per session scan C 7283e8de1d81

Subscribe to this mod's changes

gsd-codebase-mapper is an agent published in the GitHub repository itsjwill/gsd-pro (81 stars, last pushed 5mo ago), licensed MIT. It adds 46 tokens to every session and 4,374 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (reaches for credential files). It is 84% identical to gsd-codebase-mapper, differing in 89 lines, and is treated as a copy.