# Phase 82: C2 Local Cache — Hot Path Exclusion (Hardening)

## Goal

Keep the Phase 79-1 C2 local cache as a research box, but **guarantee it is not evaluated on hot paths** (alloc/free), so it cannot accidentally affect SSOT performance while remaining available for future research.

This matches the repo’s layout-tax learnings:
- Avoid physical deletion/link-out for “unused” features (can regress via layout changes).
- Prefer **default OFF + not-referenced-on-hot-path** for frozen research boxes.

## What changed

Removed any alloc/free hot-path attempts to use C2 local cache.

- Alloc hot path: `core/box/tiny_front_hot_box.h`
  - C2 local cache probe blocks removed.
- Free legacy fallback: `core/box/tiny_legacy_fallback_box.h`
  - C2 local cache probe blocks removed.

Includes and implementation files remain in the tree (research box preserved):
- `core/box/tiny_c2_local_cache_env_box.h`
- `core/box/tiny_c2_local_cache_tls_box.h`
- `core/front/tiny_c2_local_cache.h`
- `core/tiny_c2_local_cache.c`

## Behavior

- `HAKMEM_TINY_C2_LOCAL_CACHE=1` does **not** change the Mixed SSOT behavior because no hot-path code checks it.
- Research work can reintroduce it behind a separate, explicit boundary when needed.