codebase-navigator

A guide for understanding large or unfamiliar code repositories by mapping packages, services, dependencies, and how functions call one another. It also covers monorepos, which are repositories containing multiple related projects.

In plain words
What is it for?
Use it to map a repository, trace a function’s callers and callees, inspect service boundaries, and investigate dependencies or circular relationships.
Why use it?
It reduces the time spent reading unrelated files and helps you find the parts of a large codebase that matter to a change.

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/saitarrun/devforge-ai/codebase-navigator
Any agent
npx skills add saitarrun/Devforge-ai --skill codebase-navigator
Clone the repo
git clone --depth 1 https://github.com/saitarrun/Devforge-ai

Made for: Claude Code, Codex.

Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 763 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 $0.00033 $0.00763
Opus 5 $0.00016 $0.00381
Sonnet 5 $0.00007 $0.00153
Haiku 4.5 $0.00003 $0.00076

Measured 2d ago against content hash 1759b696240a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-navigator 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.

skills/codebase-navigator/SKILL.md · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Large-Scale Codebase Navigation & Comprehension Skill

This skill defines standard methodology for navigating, mapping, and understanding massive enterprise repositories, microservices, and monorepos (e.g., Turborepo, Nx, Lerna, Go workspaces, multi-package repositories).


1. Multi-Tier Exploration Strategy

When exploring an unfamiliar or massive codebase, never blindly read random files. Follow this 4-tier navigation sequence:

[Tier 1: Architectural Topography]
  → Package manifests (package.json, go.mod, Cargo.toml, pyproject.toml)
  → Workspaces / Monorepo layout
  → Domain Context (CONTEXT.md, README.md, docs/adr/)
          ↓
[Tier 2: Structural Knowledge Graph (code-review-graph)]
  → Submodule / Service boundary dependency map
  → Module coupling & circular dependency detection
          ↓
[Tier 3: Symbol & Call-Graph Tracing]
  → Entrypoints (routes, CLI commands, queue consumers, gRPC handlers)
  → Caller / Callee hierarchy for critical abstractions
          ↓
[Tier 4: Precision Target Inspection]
  → Focused file/function reading with bounded context

2. Structural Querying Priority

Always query code semantics rather than relying on noisy keyword matching:

Priority Tool / Mechanism Best Used For
1. Primary code-review-graph / LSP AST Understanding symbol definitions, call hierarchies, cross-module couplings, and change impact
2. Secondary Ripgrep / Structural Grep Fast discovery of specific error strings, environment variables, config keys, or regex tokens
3. Fallback Glob / Directory Traversal Mapping tree hierarchy when building high-level system mental models

3. High-Leverage Navigation Patterns

Pattern A: Tracing Ingress-to-Egress Dataflows

When tracking an end-to-end user action in a complex repo:

  1. Locate Ingress: Identify API route handler or message queue listener (/api/v1/..., @Post(), def handle_event).
  2. Trace Service Layer: Inspect domain service orchestration logic and business validation rules.
  3. Trace Persistence Layer: Examine database repository, ORM queries, and transaction boundaries.
  4. Inspect Egress Side-Effects: Check emitted events (Kafka/RabbitMQ), outbound webhooks, or cache invalidation calls.

Read the full file on GitHub · 75 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 · 75 lines · 33 tokens per session scan A 1759b696240a

Subscribe to this mod's changes

codebase-navigator is a skill published in the GitHub repository saitarrun/Devforge-ai (5 stars, last pushed 19d ago), licensed Apache-2.0. It adds 33 tokens to every session and 763 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 2026-08-31.

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