Pure tree-walker that converts CustomModifierDescriptor (or just an
EffectPrimitiveNode array) to a human-readable English narrative.
- Static KIND_NARRATORS map covers all 21 primitives (14 existing + 7
T1-extension trigger kinds: on-move, on-turn-end, on-promotion,
on-check-received, on-check-delivered, on-moved-onto-square,
on-captured) — no PRIMITIVE_REGISTRY lookup so the module stays free
of engine/Session/Rete imports.
- Cycle guard via WeakSet on node identity outputs '…' on revisit;
length cap 4000 chars truncates with ' … and N more primitives'.
- Performance: 0.091ms avg on 50-node descriptor (11x under the 1ms
budget for live preview).
- 34 tests cover every kind, nested combinations, cycle handling,
truncation, and perf microbenchmark.
Used by the live-preview pane (T17) added later in this epic.
Joey Yakimowich-Payne
d44b433889