# Phase 20.9 Plan — Rust‑less Kernel (Script→C ABI)

Milestones
1) C‑ABI Surface (read‑only first)
- Add/confirm header declarations:
  - `hako_gc_stats() -> char*` (caller frees with free())
  - `hako_gc_roots_snapshot() -> int64_t`
  - (Future/gated) `hako_gc_collect/start/stop -> void`
- Notes: Prototypes exist for GC; extend for console/time/string as needed.

2) LLVM Lowering (llvmlite)
- Lower `env.gc.stats/0` → `hako_gc_stats` (bridge i8* → handle via boxer)
- Lower `env.gc.roots_snapshot/0` → `hako_gc_roots_snapshot`
- Keep control hooks for later (gated, no‑op/Fail‑Fast).

3) GcBox Policy (Hakorune)
- Wrap read‑only calls; add lightweight cadence/log formatting (dev gate).
- Provide sample `policy_tick()` usage in docs.

4) Canary Smokes (gated)
- LLVM canaries (read‑only): `SMOKES_GC_ENV_LLVM=1`
  - stats expects JSON with keys, roots_snapshot expects integer
- VM parity exists via adapter; LLVM confirms script→C ABI path.

5) Diagnostics Parity
- Maintain short lines for NOT_FOUND/UNSUPPORTED/VALIDATION on both VM and LLVM.
- Ensure canaries fail with short lines when symbols missing (gate remains OFF by default).

Acceptance Checklist
- [x] stats/roots_snapshot canaries PASS under LLVM with provided symbols
- [x] GcBox.stats()/roots_snapshot() return same shapes across VM/LLVM
- [x] collect/start/stop are defined, gated, and do not silently succeed
- [x] Docs updated (bridge plan/roadmap/usage) and gates documented

Rollback
- Remove/disable C shims; LLVM canaries remain gated OFF; VM path unaffected.

Links
- ./CHECKLIST.md, ./README.md
- ../../../development/architecture/abi/hakorune-c-abi-bridge.md
- ../../../development/architecture/gc/llvm-extern-plan.md