fallow

fallow is a skill for Claude Code, Codex from fallow-rs/fallow-skills. It costs 114 tokens per session (12,728 once invoked), scanned C, original, MIT.

A codebase analysis tool for TypeScript and JavaScript projects. It examines code, styles, dependencies, architecture, and—when enabled—runtime coverage, which shows what code actually runs.

In plain words
What is it for?
Use it to find unused files and exports, repeated or overly complex code, dependency cycles, boundary violations, styling drift, dead CSS, feature-flag problems, and similar code.
Why use it?
It helps reveal cleanup work and maintenance risks that are easy to miss during ordinary feature development, such as duplication, circular dependencies, stale flags, and unused code.

Skill for Claude CodeCodex

Written for Claude Code and Codex: $ARGUMENTS substitution, but also agents/openai.yaml present. Also seen: mentions Claude Code; mentions AGENTS.md; mentions Codex.

Part of the fallow plugin — 2 skills, 1 command shipped together

Good fit Use it to find unused files and exports, repeated or overly complex code, dependency cycles, boundary violations, styling drift, dead CSS, feature-flag problems, and similar code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fallow-rs/fallow-skills/fallow
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.

Any agent
npx skills add fallow-rs/fallow-skills --skill fallow
Clone the repo
git clone --depth 1 https://github.com/fallow-rs/fallow-skills

Made for: Claude Code, Codex.

Or install fallow, the plugin that ships this one along with the rest of its 2 skills, 1 command.

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 fallow

README.md
[![agentmods](https://agentmods.dev/badge/skills/fallow-rs/fallow-skills/fallow.svg)](https://agentmods.dev/skills/fallow-rs/fallow-skills/fallow)
Your own site
<a href="https://agentmods.dev/skills/fallow-rs/fallow-skills/fallow"><img src="https://agentmods.dev/badge/skills/fallow-rs/fallow-skills/fallow.svg" alt="Measured on agentmods" height="20"></a>
Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 12,728 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 22 May 2026
  • Snyk pass 22 May 2026
How audits are shown
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 5.1 $0.00114 $0.12728
Opus 5 $0.00057 $0.06364
Sonnet 5 $0.00023 $0.02546
Haiku 4.5 $0.00011 $0.01273

Measured 2d ago against content hash 6f43bd8e29d7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

fallow scanned grade C with 2 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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

| `health` | Function complexity analysis (also covers component templates as synthetic `<template>` findings: Angular external `.html` files via `templateUrl` AND inline `@Component({ template: \`...\` })` literals, plu

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

| `boundary-violation` | `--boundary-violations` | - | `// fallow-ignore-next-line boundary-violation` | Imports crossing architecture zone boundaries. Presets: `layered`, `hexagonal`, `feature-sliced`, `bulletproof`; `a
fallow/skills/fallow/SKILL.md · 499 lines

How it starts

The opening of the file, as written. The whole thing — 499 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fallow: codebase intelligence for TypeScript and JavaScript

Codebase intelligence for TypeScript and JavaScript. The static layer analyzes code and styles and reports quality, changed-code risk, cleanup opportunities, circular dependencies, code duplication, complexity hotspots, architecture boundary violations, design-system styling drift, feature flag patterns, and opt-in security candidates. Runtime coverage merges production execution data into the same fallow health report for hot-path review, cold-path deletion confidence, and stale-flag evidence, with a single local capture available by default and continuous/cloud runtime monitoring available as an optional mode. Broad framework plugin coverage, zero configuration, sub-second static analysis.

When to Use

  • Find cleanup opportunities: unused files, exports, types, members, dependencies, or stale flags.
  • Detect code duplication, circular dependencies, architecture boundary issues, and complexity hotspots.
  • Find functions that may implement the same intent despite different names, syntax, or control flow (fallow similar-code).
  • Check styling consistency, CSS dead surface, and design-token drift.
  • Audit changed code before a commit, PR, release, or refactor.
  • Set up CI quality gates, duplication thresholds, and regression baselines.
  • Auto-fix supported unused exports and dependencies after --dry-run.
  • Investigate why a specific export, dependency, file, or issue type was reported.
  • Surface local security candidates for an agent to verify (fallow security).
  • Find untested but runtime-reachable code (fallow health --coverage-gaps).
  • Rank complexity hotspots, owners, and refactoring targets (fallow health --hotspots --ownership --targets).
  • Review what fallow has surfaced over time (fallow impact).
  • Confirm exact TypeScript symbol use, affected tests, API leaks, or public type coupling when syntactic evidence is insufficient (--type-aware).

When NOT to Use

  • Runtime error analysis or debugging
  • Type checking (use tsc for that). Type-aware fallow consumes checker evidence for project-wide analysis but does not report compiler diagnostics.
  • Linting style or formatting issues (use ESLint, Biome, Prettier)
  • Verified security vulnerability scanning or SAST. fallow security surfaces local, deterministic security candidates for a downstream agent to verify; it does not prove exploitability. Use Snyk, CodeQL, or Semgrep for verified scanning, and an SCA tool for dependency CVEs.
  • Bundle size analysis
  • Projects that are not JavaScript or TypeScript

Read the full file on GitHub · 499 lines

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 Changed · +1 lines 6f43bd8e29d7
  2. 8d ago First seen · 498 lines · 114 tokens per session scan C 88fbecfaef1d

Subscribe to this mod's changes

fallow is a skill published in the GitHub repository fallow-rs/fallow-skills (119 stars, last pushed today), licensed MIT. It adds 114 tokens to every session and 12,728 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it C with 2 findings (hidden instructions, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.