monorepo-detection

name	monorepo-detection
description	Canonical rules for detecting monorepo/workspace structure (Turborepo, pnpm workspaces, npm/yarn/bun workspaces) and locating the target app or package directory. Reference-only skill preloaded by other skills/subagents.
when_to_use	When any skill or agent needs to determine whether a project is a monorepo and, if so, pick the correct sub-package directory for further operations.
user-invocable	false

Monorepo Detection

Single source of truth for monorepo detection. Any skill or agent that previously inlined monorepo checks (prd, design-system, code-reviewer) must defer here.

Detection order

Inspect the repository root (the directory containing .git/) in this order:

Signal	Monorepo tool
turbo.json present at root	Turborepo
pnpm-workspace.yaml present at root	pnpm workspaces
Root package.json contains a workspaces array or object	npm / yarn / bun workspaces
nx.json present at root	Nx
lerna.json present at root	Lerna

If none match, the project is a single-package repo. Return monorepo: false and set targetDir to the repo root.

Locating the target sub-package

When a monorepo is detected and the task scope implies a specific app or package, pick the target directory by the work context:

Work context	How to pick
Web / frontend work	Find the directory containing react-router.config.ts, next.config.*, or vite.config.*
Mobile work	Find the directory containing Expo config (app.config.ts / app.config.js / app.json with an expo key) AND expo in its package.json dependencies
Backend / API work	Find the directory containing nest-cli.json or an equivalent backend framework config
Shared package (types, utils, etc.)	The directory under packages/ most commonly referenced by app directories

If multiple directories match the same work context (e.g., two Expo apps), do not guess — ask the user.

Fall back to the repo root only for shared tooling (root package.json scripts, CI config).

Output contract

type MonorepoDetectionResult = {
  monorepo: boolean;
  tool: 'turbo' | 'pnpm-workspaces' | 'workspaces' | 'nx' | 'lerna' | null;
  repoRoot: string; // absolute path containing .git/
  targetDir: string; // absolute path of the sub-package chosen, or equal to repoRoot when not a monorepo
};

Coordination with framework-detection

framework-detection must run inside targetDir, not at repoRoot. Running it at the wrong level gives wrong results for monorepos (e.g., root package.json may list only devDeps).