NA: Carve movement / zoned / compaction monoliths by interface

[arniber21]

Parent

#201

Context

Domain algorithms are deep; modules are monoliths:

File	~LOC	Clusters
movement.rs	1797	params, plan_aod_movement, duals/pack, geometry R1–R3, banks, legality
compaction.rs	1124	deps/ASAP, merge classes, geometry verify, force_merge
zoned.rs	1049	ZoneSpec/arch, cost, schedule_zoned, placer modes

Helpers like layer_has_entangle / geometry predicates are copy-pasted across files. Goal is navigability and locality, not algorithm rewrites.

What to build

Split by interface without changing planner behavior:

• geometry / R1–R3 checkers (shared)
• conflict / bank packing
• placer search vs cost evaluation
• compaction merge policy vs verify

Share layer predicates. Keep public entrypoints (plan_aod_movement, schedule_zoned, compact_schedule) stable.

Acceptance criteria

• Geometry / legality predicates have one module; movement and compaction both call it
• No intentional schedule changes (existing NA tests / snapshots gold)
• Largest file size drops materially (target: no single planner file ≫ ~800 LOC without a documented reason)
• Module headers describe each interface’s invariants

Blocked by

Prefer landing ZoneKind (#212) first if zone types move. Not blocked on #211 unless files are rewritten there.

Related

#201, #212, ADR-0008