T18 review (Phase 1) noted the NICE-tier trim drops previous-scene
FIRST while §6.3 spec lists previous-scene LAST in the NICE tier
group. Decision: keep the existing greedy order (previous-scene
first), and document why.
Rationale (now in code at the trim ladder):
1. Cheapest-impact-first — a per-POV previous-scene summary loses
less narrative continuity than the older dialogue turns or
memory hits it competes with.
2. Greedy lookahead is more expensive than the marginal narrative
loss. Dropping previous-scene typically clears the soft-budget
slack in one step.
Test added: test_nice_trim_order_documented pins the observed order
(previous-scene -> memories -> dialogue) so a future refactor can't
silently invert it. Sized so that all-NICE config overflows soft but
dropping just previous-scene fits — proves memories and older
dialogue turns survive while previous-scene is the FIRST drop.
Joseph Doherty
73bb8c1f17