local-environmentlisted

# Local environment — bring it up, seed it, drive it - **Can:** install, seed, bring up and drive the local environment, and stand in for external services. - **Must:** use the project's documented commands and keep every secret out of git. - **Cannot:** commit a filled-in `.env`, or point a local process at a production resource. This skill covers **getting it running**. Proving the change works is the `local-testing` skill. ## 1. Installation ```bash {{PKG_MANAGER}} install # dependencies cp .env.example .env # variables — NEVER commit a filled-in .env {{CMD_DEV}} # bring it up ``` Opens at `{{LOCAL_URL}}`. ### Dependencies that vary by platform Not every dependency exists on every system. When the project has one that only runs on some platforms, three things must be true — and all three get verified, not assumed: 1. installation is **conditional** (environment marker in the manifest), so the install does not break on the other platforms; 2. there is a documented **alternative backend** for the rest; 3. the choice is **automatic in the code**, in one place, and a missing engine raises a **readable** error — never an import stack trace. ⚠️ **Never import a platform-specific engine directly in feature code** — always through the layer that picks. That is the error that breaks the whole project on someone else's machine. ## 2. Stand-ins for external services If the project depends on a paid/production external service, exercising ag