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.
npx agentmods add skills/anilburcu/claude-code-react-native/monorepo-metronpx skills add AnilBurcu/claude-code-react-native --skill monorepo-metrogit clone --depth 1 https://github.com/AnilBurcu/claude-code-react-nativeWrote 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/skills/anilburcu/claude-code-react-native/monorepo-metro)<a href="https://agentmods.dev/skills/anilburcu/claude-code-react-native/monorepo-metro"><img src="https://agentmods.dev/badge/skills/anilburcu/claude-code-react-native/monorepo-metro.svg" alt="Measured on agentmods" 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 | $0.00063 | $0.00855 |
| Opus 5 | $0.00032 | $0.00428 |
| Sonnet 5 | $0.00013 | $0.00171 |
| Haiku 4.5 | $0.00006 | $0.00085 |
Grade A, and why
monorepo-metro 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 6d 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 — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.
React Native in a monorepo
First, delete the folklore
Modern expo/metro-config configures Metro for monorepos automatically. If the repo carries a hand-written metro.config.js full of watchFolders, nodeModulesPaths, extraNodeModules or disableHierarchicalLookup copied from an old blog post, that config is now the most likely cause of the problem, not the fix. Strip it down to the default Expo config, run npx expo start --clear once, and re-test before debugging anything else.
The problems that remain after that are real, and they are all below.
Singletons, the actual monorepo disease
react, react-native and the native-module packages must resolve to exactly one copy for the app. Two copies produce the classic signatures:
- "Invalid hook call" with a perfectly valid component
- "Tried to register two views with the same name"
- A native module that works in one workspace app and crashes in another
Diagnose with the package manager, not by staring at code: npm ls react-native (or yarn why react-native, pnpm why react-native) from the repo root. More than one resolved version, or the same version in two physical locations, confirms it.
Fix at the root: pin the singletons with the root manifest's override mechanism (overrides for npm, resolutions for yarn, pnpm's overrides). Then reinstall from the root and re-run the check. If the lockfile seems to hold onto stale resolutions after the override, a full reinstall of node_modules is legitimate here; this is the deliberate-upgrade case, not build-error cache thrashing.
Hoisting strategies decide your failure mode
- npm and yarn hoist: a package you forgot to declare still resolves because a sibling declared it. Everything works locally and then fails on EAS or on a colleague's machine with a different install order. The bug is the undeclared dependency, not the machine.
- pnpm and bun isolate: undeclared dependencies fail immediately and loudly. More friction on day one, dramatically fewer ghosts later.
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.
- 6d ago First seen · 47 lines · 63 tokens per session scan A 08e0ffc6d2ba
monorepo-metro is a skill published in the GitHub repository AnilBurcu/claude-code-react-native (3 stars, last pushed 1mo ago), licensed MIT. It adds 63 tokens to every session and 855 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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