C3: State Surface Declared¶

Enforces P2: Each harness is stateful.

BlockContract.state_surface is required. A StateSurface declares:

• persistence — none, run, session, project, or global
• queryable_via — e.g. scorecard, ledger, or snapshot_export
• retention — how long the state is kept

persistence: none is legal, but it must be declared rather than left implicit.

Enforced at: tests/contract/test_state_surface_declared.py.