# Core (/docs/api-reference/core)



The `@vlandoss/env` entrypoint is the only one you always import — it contains the runtime-agnostic core. Adapter entrypoints (`/node`, `/vite`, `/react`, `/zod`) build on top of it.

## Exports [#exports]

| Export      | Kind     | Summary                                                                                                                                                                                               |
| ----------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `schema`    | Function | Declare the contract — branches and Standard Schema leaves.                                                                                                                                           |
| `defineEnv` | Function | Merge config + environment variables, validate, and return a typed `env` object.                                                                                                                      |
| `envName`   | Function | Detect the current environment name across runtimes — `development`, `production`, …                                                                                                                  |
| `readEnv`   | Function | Read raw values from the active source (`process.env` on the server, `window.__env` in the browser). Returns `{}` on runtimes without `process` (Workers) — pass `runtimeEnv` to `defineEnv` instead. |
| `Config`    | Type     | The input shape of per-environment config files for a given schema.                                                                                                                                   |
| `Env`       | Type     | The output shape of the resolved `env` object for a given schema.                                                                                                                                     |

<Callout type="info">
  Full signatures and option tables are coming soon. Until then, see
  [Concepts → Overview](/docs/concepts/overview) for the mental model and
  [Quickstart](/docs/getting-started/quickstart) for a runnable example.
</Callout>

## See also [#see-also]

* [Concepts → Resolution order](/docs/concepts/resolution) — how `defineEnv` merges sources.
* [Concepts → Env-var naming](/docs/concepts/env-var-naming) — how schema paths map to env-var names.
* [Concepts → `envName()`](/docs/concepts/env-name) — precedence and the Vite gotcha.