fix(typing): annotate the __init_subclass__ hooks, which strict type checkers refuse to call untyped

[earakely-scale]

Every __init_subclass__ hook in agent_env is now fully annotated, so a downstream package that type-checks strictly can subclass agent_env's classes again.

Why

agent_env ships py.typed, so a consumer's type checker checks its subclasses of agent_env's classes, and defining a subclass calls the base's __init_subclass__. Under mypy --strict (disallow_untyped_calls), calling a function with no annotations from typed code is an error, so every subclass of SandboxProvider has failed with Call to untyped function "__init_subclass__" in typed context [no-untyped-call] since 0.9.1312 (#159) added that hook. Universe's hook has the same problem.

What

• SandboxProvider.__init_subclass__ and Universe.__init_subclass__ are now (cls, **kwargs: Any) -> None. TaskStep's already annotated its return, and gets **kwargs: Any for the same shape.
• A unit test walks src/agent_env and fails on any __init_subclass__ that leaves a parameter or the return unannotated, since a subclass can't avoid calling one.

Tests

Unit tier: 7,415 passed. A strict-mypy downstream package that subclasses ModalSandboxProvider fails with the error above on 0.9.1313 and type-checks clean on this branch.

🤖 Generated with Claude Code

Confidence Score: 5/5

The PR appears safe to merge; the previous test issue is fixed and no new actionable issues remain.

Summary

Adds type annotations to __init_subclass__ hooks so strict type checkers accept downstream subclasses.

• Strict type checkers can follow agent_env subclass hooks.

_{Reviews (2) · Last reviewed commit: "test(typing): the hook test skips cls wh..." · Reviewed by Greptile}