codebase-understanding

codebase-understanding is a skill for Claude Code, Codex from OneDro1d/dark-factory. It costs 73 tokens per session (435 once invoked), scanned A, original, Apache-2.0.

A skill for finding the right service and files in a codebase by reading its existing maps, findings, decisions, and service notes before searching source code.

In plain words
What is it for?
Use it when you need to find where something lives, understand how a feature works, locate an owner service, or identify the files involved in a flow.
Why use it?
It avoids repeatedly scanning the whole repository to rediscover information that is already documented. This makes investigations and reviews more focused and less time-consuming.

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/onedro1d/dark-factory/codebase-understanding
Any agent
npx skills add OneDro1d/dark-factory --skill codebase-understanding
Clone the repo
git clone --depth 1 https://github.com/OneDro1d/dark-factory

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for codebase-understanding

README.md
[![agentmods](https://agentmods.dev/badge/skills/onedro1d/dark-factory/codebase-understanding.svg)](https://agentmods.dev/skills/onedro1d/dark-factory/codebase-understanding)
Your own site
<a href="https://agentmods.dev/skills/onedro1d/dark-factory/codebase-understanding"><img src="https://agentmods.dev/badge/skills/onedro1d/dark-factory/codebase-understanding.svg" alt="Measured on agentmods" height="20"></a>
Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 435 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 $0.00073 $0.00435
Opus 5 $0.00036 $0.00217
Sonnet 5 $0.00015 $0.00087
Haiku 4.5 $0.00007 $0.00044

Measured 2d ago against content hash abca92f2cda4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-understanding 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/df-context-store/substrate-template/dotclaude/skills/codebase-understanding/SKILL.md · 30 lines

What it actually says

Codebase Understanding (read-first, low-token)

Goal: locate the relevant code in the fewest tokens. NEVER scan the whole repo to answer a question the context store already answers.

Order of reading (stop as soon as you have what you need)

  1. .claude/context/SERVICE-MAP.md — which service/db/queue/API owns this area.
  2. .claude/context/FINDINGS.md — is this already known/solved?
  3. .claude/context/DECISIONS.md — is the current behavior intentional?
  4. The ONE relevant <service>/CLAUDE.md — contracts, key files, gotchas.
  5. The shared-models CLAUDE.md — only when tracing a routing key / RPC across services.
  6. Source — targeted, by file:line from the above, via Grep/Read. Not whole-file dumps unless necessary.

Cheap search patterns

  • Routing key / RPC: grep -rn "<routing.key>" <service>/ then open the dispatcher.
  • A symbol: grep -rn "MethodName\|TypeName" <service>/ --exclude-dir={obj,bin}.
  • A flow: start at the SERVICE-MAP "In → Out" column, follow the routing key to the next consumer.

Output

A short "where it lives" answer: service, file:line, and the one-line role. Do not paste large code blocks — cite locations.

Don't

  • Don't re-derive the architecture; it's in SERVICE-MAP/CLAUDE.md.
  • Don't read every service. Read the one(s) the map points to.
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 · 30 lines · 73 tokens per session scan A abca92f2cda4

Subscribe to this mod's changes

codebase-understanding is a skill published in the GitHub repository OneDro1d/dark-factory (0 stars, last pushed today), licensed Apache-2.0. It adds 73 tokens to every session and 435 once invoked, about $0.0004 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 2026-09-01.

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