- LLMPolicy is now Callable[[Observation], tuple[Action, ...]]: the snapshot
is the policy's sole information source; the live CombatantState is no
longer passed to new-style policies.
- CombatEngine._llm_adapter keeps a compatibility path for pre-D1
two-argument callables: the signature is inspected ONCE at wrap time
(_accepts_state) and legacy policies still receive (observation, state).
- Observation.to_dict() carries schema_version (OBSERVATION_SCHEMA_VERSION=1)
as its first pinned key; bump only on removal/meaning change.
- Pinned keyset tests updated (test_observation, test_observation_enriched);
new tests: observation-only e2e, legacy 2-arg e2e through the adapter,
schema_version pin + JSON-serializability.
- README: documents the new entry signature and the schema_version key.
ctan