hakorune/docs/private/roadmap/phases/phase-20.10/PLAN.md

Phase 20.10 — Migration Plan (Script‑First Runner)

Phases

1. Runner Facade in Script (lang)

• Provide a thin Script Runner that orchestrates entry selection and delegates execution to current backends.
• Keep VM/LLVM selection in Rust; the script facade focuses on entry/args and pre/post hooks.
• Default: ON（opt‑out via HAKO_SCRIPT_RUNNER=0|off|false）。
• Pre‑invoke emits stable short lines（stdout）: invoke / invoke: FAIL。
• UsingResolver probes: HAKO_USING_RESOLVER_FRONT|COMPARE|SHADOW（挙動不変）。

2. Extern/Effects SSOT（spec + generator; STRICT checks）

• specs/externs.toml を SSOT とし、dev ツールで Python/Rust に生成・同期。
• Drift チェックは STRICT（ズレは FAIL）。
• Effects の取り込みは env ゲート（HAKO_EXTERN_EFFECTS_SSOT=1 → Io を反映）。

3. CLI/ENV Harmonize

• Add CLI flags (done in 20.9) and align HAKO_* first; ENV remains helper overrides.
• Document precedence: CLI > ENV > TOML. Provide quickref in docs/guides/env-variables.md.

4. Extern via C‑ABI (policy flip under gate)

• Ensure all script‑visible externs lower to hako_* (AOT) and forbid dotted C symbols in STRICT.
• Gate: CI_STRICT=1 for dotted symbol check.

5. Smokes & Parity

• Add representative integration-core parities (done: env.local.get exists/missing, console.warn/error).
• Add failure diagnostics (done: mir_emit_failed; have symbol_missing already).
• Add runner representative smokes（invoke/trace/workspace-only; quick + integration-core）。

6. Rollback & Safety

• All new pieces are opt‑in by flags. Removing gates reverts to current behavior.

7. Selfhost Launcher (AOT)

• Produce lang/bin/hakorune via lang/build/build_runner.sh（LLVM18 dev）。
• Quick smoke builds and runs the launcher (exit code=0)。

8. Final Goal（配布イメージ）

• git/hakorune-selfhost/lang/bin/hakorune を自己ホストバイナリとして常備。
• CI（将来）で lang/build/build_runner.sh を build-only に組み込み、canary 実行で健康診断。

Notes

• Python backend remains as-is. This phase focuses on boundaries, contracts, and runner facade.
• Ref‑VM continues as a reference for semantics; production runs are Rust VM/LLVM.