Fallow is a command-line static-analysis tool that builds a dependency graph of TypeScript and JavaScript code to identify unused code, duplication, circular dependencies, complexity hotspots, boundary violations, and styling drift. It is for developers reviewing codebases and verifying changes, with catalogue entries that add agent, editor, and workflow integrations.
Borrowing it
Nothing to install: this file belongs to fallow-rs/fallow. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/fallow-rs/fallow/main/AGENTS.mdgit clone --depth 1 https://github.com/fallow-rs/fallowWrote 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.
[](https://agentmods.dev/instructions/fallow-rs/fallow/agents-md)<a href="https://agentmods.dev/instructions/fallow-rs/fallow/agents-md"><img src="https://agentmods.dev/badge/instructions/fallow-rs/fallow/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/fallow-rs/fallow/agents-md"><img src="https://agentmods.dev/badge/instructions/fallow-rs/fallow/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01122 | $0.01122 |
| Opus 5.5 | $0.00449 | $0.00449 |
| Sonnet 5.5 | $0.00224 | $0.00224 |
| Haiku 4.5 | $0.00112 | $0.00112 |
Grade A, and why
fallow 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 17d 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.
How it starts
The opening of the file, as written. The whole thing — 129 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Fallow agent guide
This file is the tracked, always-loaded router for Codex. Keep it short. Durable
architecture, validation, and review knowledge belongs under docs/, while
repeatable workflows belong under .agents/skills/.
Start here
- Read
docs/README.mdfor the maintained documentation map. - Use
docs/development/task-context-map.mdto load only the references required for the task. - Load the matching workflow from
.agents/skills/<name>/SKILL.md. - Follow nested
AGENTS.mdfiles when working in a scoped subsystem.
The shared development references are:
docs/development/repo-map.mddocs/development/quality-gates.mddocs/development/review-routing.mddocs/development/ai-tooling.md
Do not rely on .codex/skills, sibling checkouts, private symlinks, or
machine-local files. A fresh clone must contain everything required by these
routes.
Workflow
Fallow's native lifecycle is authoritative:
implement -> panel-review -> review -> ship -> sweep
Use the corresponding tracked skills under .agents/skills/. Codex consumes
that canonical tree directly. Claude adapters under .claude/skills/ are
generated and must pass npm run check:agent-adapters.
Before editing, check the current branch and worktree. Other agents may be working in the same checkout. Re-read files immediately before editing, keep changes narrowly scoped, and never revert unrelated work.
Architecture
The analysis pipeline is:
config -> discovery -> extract -> resolve -> graph -> analyze -> output
Use docs/development/repo-map.md for crate
ownership and high-value paths. Important invariants:
- Fallow performs syntactic analysis with Oxc, without the TypeScript compiler.
- Use
FxHashMapandFxHashSetinstead of the standard hash collections. - Re-export chains and workspaces are first-class graph concerns.
- JSON, SARIF, CodeClimate, LSP, MCP, and editor output are public contracts.
- LSP and MCP should remain thin integration layers over shared analysis.
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.
- 17d ago Changed · -5 tokens per session 0b3fda10d126
- 1mo ago First seen · 129 lines · 1,127 tokens per session scan A b8ec81528bb6
fallow is an instructions file published in the GitHub repository fallow-rs/fallow (5,139 stars, last pushed today), licensed MIT. It adds 1,122 tokens to every session, about $0.0045 per session on Opus 5.5. 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 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).