✅ Belphegor exhausts after fusion as top

Category	Ability
Status	Passing
Test	tests/test_abilities_complex.py::TestBelphegorTriggers::test_belphegor_exhausts_after_fusion_as_top

When Belphegor is the TOP card in a fusion, the result must be EXHAUSTED.

Preconditions

• Belphegor (#051) is the top card, now fused (is_fused=True), currently READIED

• (fusion normally readies the demon, but Belphegor's passive overrides this)

Action

• Fire FUSION_PERFORMED event with source = fused Belphegor

result = fire_event(state, event)
belphegor_after = next(d for d in result.demons if d.unit_id == "051")

Expected Postconditions

• Fused Belphegor: EXHAUSTED

Assertions

assert belphegor_after.state == DemonState.EXHAUSTED, (
    f"Belphegor (top of fusion) must be EXHAUSTED. Got {belphegor_after.state}."
)