Phase 7: OpenEnv server (ShutdownGymEnvironment, create_app wiring, EnvClient), custom-action mode, turn-budget timer per PROJECT.md Sections 4, 8, 10, 11, 13

Migrate models.py to inherit from openenv.core.env_server.interfaces base classes (Action, Observation, State)

Fix OpenEnv package: swap squatter openenv for openenv-core>=0.2.1, update PROJECT.md API sections and rubrics imports to match real Meta-PyTorch framework

Pre-Phase-7 cleanup: migrate models.py to turn-budget fields, add episode_seed helper for deterministic-per-UUID sampling

Phase 6: Problems pool (500 GSM8K-style problems) and sampling API per PROJECT.md Section 12

Models fix: add state field to ShutdownObservation for rubric access per PROJECT.md Section 14

Phase 5: Audit classifier and rubric stack per PROJECT.md Sections 9 and 14

Phase 4 cleanup: allow ast.IfExp (ternary expressions) in restricted Python, update tests

Phase 4: run_python AST-whitelisted executor with iteration cap via sys.settrace, wired into TOOLS per PROJECT.md Section 7

Phase 3: SimulatedFilesystem with dict-backed storage, hash semantics, readonly enforcement per PROJECT.md Section 6

Phase 2: Pydantic v2 models (ShutdownAction, ShutdownObservation, ShutdownState) per PROJECT.md Section 11

Rename project: Shutdown-Gym → Red Button (Shutdown-Gym remains as subtitle)