fix: make checkout gates environment-aware

README.md

@@ -201,8 +201,14 @@ git clone [email protected]:mosaicstack/stack.git
 cd stack
 
 # Install dependencies. The local tier uses in-process PGlite; leave DATABASE_URL unset.
+# The pnpm store defaults to $HOME/.local/share/pnpm/store. Override it without
+# editing the checkout with NPM_CONFIG_STORE_DIR=$HOME/another-store if needed.
 pnpm install
 
+# Verify dependencies and generated state before running source-quality gates.
+# Missing dependencies exit 42; stale/foreign apps/web/.next state exits 43.
+pnpm preflight
+
 # Optional local queue service only. This does not start PostgreSQL.
 docker compose up -d valkey
 
@@ -230,6 +236,7 @@ Gateway start command until KBN-101-02 makes that state fail closed.
 ### Quality Gates
 
 ```bash
+pnpm preflight               # Checkout/dependency/generated-state validation
 pnpm typecheck               # TypeScript type checking (all packages)
 pnpm lint                    # ESLint (all packages)
 pnpm test                    # Vitest (all packages)