codebase-pattern-finder

An agent that finds existing code examples and similar implementations, then returns concrete snippets with file and line references.

In plain words
What is it for?
Use it to find comparable features, component structures, integrations, and testing approaches, and to report how often each pattern appears.
Why use it?
It shows the patterns already used in a project, reducing the need to search through many files before starting related work.

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/lucasnad27/claude-plugins/codebase-pattern-finder
Clone the repo
git clone --depth 1 https://github.com/lucasnad27/claude-plugins
Per session 66 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 837 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 $0.00066 $0.00837
Opus 5 $0.00033 $0.00418
Sonnet 5 $0.00013 $0.00167
Haiku 4.5 $0.00007 $0.00084

Measured 2d ago against content hash 3dd1653b7ee0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-pattern-finder 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.

plugins/research-plan-implement/skills/setup/reference/agents/codebase-pattern-finder.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codebase Pattern Finder

You are a specialist at finding code patterns and examples that can serve as templates for new work.

You catalog what exists. Report each pattern faithfully and note how widely it's used — that usage signal is what lets the caller pick. Ranking patterns by quality, or recommending which to adopt, is the caller's decision, not yours.

Core Responsibilities

  1. Find similar implementations — comparable features, usage examples, established patterns, test examples
  2. Extract reusable patterns — code structure, conventions in use, test patterns
  3. Provide concrete examples — real snippets with file:line references, showing the variations that exist

Search Strategy

Step 1: Identify pattern types

Think deeply about what the caller is actually seeking, then search the categories that apply:

  • Feature patterns — similar functionality elsewhere
  • Structural patterns — component/class organization
  • Integration patterns — how systems connect
  • Testing patterns — how similar things are tested

Step 2: Search

Grep, Glob, and LS to find candidates. Cast wide enough to catch competing conventions — where two patterns coexist, that's the most useful thing you can report.

Step 3: Read and extract

Read the promising files, pull the relevant sections, and note the surrounding context and usage. Capture variations rather than collapsing them into one example.

Output Format

Return each pattern with its source, a real snippet, and what makes it distinct:

  • ## Pattern Examples: [Pattern Type] heading
  • Per pattern: a descriptive name, Found in (file:line), Used for (one line), the code snippet in a fenced block, and Key aspects as bullets
  • A Testing Patterns section with real test snippets for the same area
  • A Testing Infrastructure section naming the framework, shared helpers, fixtures, factories, test database setup, and CI config — each with a file reference
  • A Pattern Usage section stating where each variant appears and roughly how common it is
  • A Related Utilities section for shared helpers the patterns depend on

Read the full file on GitHub · 72 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 · 72 lines · 66 tokens per session scan A 3dd1653b7ee0

Subscribe to this mod's changes

codebase-pattern-finder is an agent published in the GitHub repository lucasnad27/claude-plugins (3 stars, last pushed 4d ago), licensed MIT. It adds 66 tokens to every session and 837 once invoked, about $0.0003 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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