/v1/environments — reusable sandbox runtime, template, and dependency definitions
An environment is a named sandbox template. Multiple agents and sessions can reference the same one; edit it once and every referencing session picks it up on its next run.
Creating an environment provisions nothing. The sandbox is created when a session referencing it runs for the first time.
The environment is resolved before each run, and a session’s environment wins over the agent’s own sandbox config. You can iterate on dependencies without recreating the session.