restore(lang): full lang tree from ff3ef452 (306 files) — compiler, vm, shared, runner, c-abi, etc.\n\n- Restores lang/ directory (files≈306, dirs≈64) as per historical branch with selfhost sources\n- Keeps our recent parser index changes in compiler/* (merged clean by checkout)\n- Unblocks selfhost development and documentation references

lang/src/tools/loader_front/LAYER_GUARD.hako

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+#![doc = "Phase 20.13 loader_front guard — define layer responsibilities."]
+
+static box LOADER_FRONT_GUARD {
+  name() { return "loader_front" }
+  allowed_imports() { return ["json", "env"] }
+  forbidden_imports() { return ["vm_core", "plugins", "ffi"] }
+}
+

lang/src/tools/loader_front/README.md

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+# loader_front — Loader Front EXE (Phase 20.13)
+
+Purpose
+- Decide high-level loading (policy/allowlist/resolution) ahead of kernel loader.
+- Output a short, stable verdict; kernel honors it strictly (no fallback).
+
+Responsibilities
+- Evaluate env/policy and candidate modules.
+- Emit: OK/NOOP/FAIL (tagged), exit code semantics same as runner_front.
+
+Inputs/Outputs
+- Input: JSON/CLI with policy keys and candidates
+- Output: one-line verdict (short) + exit code
+
+ENV (planned; default OFF)
+- HAKO_LOADER_USE_SCRIPT_EXE=1 (alias NYASH_*) — enable loader front EXE
+- HAKO_QUIET=1 — quiet mode adherence
+
+Non‑Goals
+- No filesystem/ABI side-effects beyond read-only inspection.
+
+TTL
+- Diagnostics/formatting migrates from Rust boundary to this front EXE when stable.
+
+Notes (AOT / Single‑EXE)
+- 将来的に単一exeに内蔵（AOT）され、ENV反映→通常ロード継続を同一プロセスで行います。
+- 開発時は tools/front_exe/loader_front.sh をゲートONで差し替え可能です。