docs: restore docs/private/roadmap from 7b4908f9 (Phase 20.31)

2025-10-31 18:00:10 +09:00
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--- a/docs/private/roadmap/phases/phase-20.26/CHECKLIST.md
+++ b/docs/private/roadmap/phases/phase-20.26/CHECKLIST.md
@ -0,0 +1,37 @@
+# Phase 20.26 — Checklist
+
+Status legend: [ ] pending, [~] in-progress, [x] done
+
+Phase A — Deprecation + Docs (safe, no behavior change)
+- [x] Deprecate banner when `llvm-inkwell-legacy` path executes (runner/modes/llvm)
+- [ ] One-time compile-time banner when feature is built (optional)
+- [x] Docs scaffold (README/PLAN/CHECKLIST) present
+- [x] CURRENT_TASK updated to Phase 20.26 focus
+
+Phase B — Archive + Feature Gates
+- [x] Move `src/backend/llvm/compiler/**` → `archive/legacy/llvm-inkwell/**`
+- [x] Keep feature wiring via shim (build stays green; feature off by default)
+- [x] Add opt-in smoke to assert deprecate banner
+
+Phase C — Runner Plan (opt-in)
+- [x] Add lang `RunnerPlanBuilder` skeleton (decision only)
+- [x] Add thin adapter in Rust runner (apply plan)
+- [x] Toggle `HAKO_RUNNER_PLAN=1` guarded; defaults unchanged
+  - v0: action ExecuteCore/ExecuteVM を適用（Gate‑C/VM）。既定不変。
+
+Phase D — hakmem (gate only)
+- [x] CLI `--mem {libc|hakmem}` to ENV (`HAKO_C_ABI_ALLOC`)
+- [x] Keep default libc; docs updated; no behavior change（introspection: `hako_allocator_name()` 追加）
+
+Status (2025-10-30)
+- quick: PASS 56 / SKIP 16 / FAIL 0
+- integration-core: PASS 26 / SKIP 0 / FAIL 0
+- Gate‑C/Core: Early routing (JSON→Interpreter) in place; no boot-plan/ny-compiler noise.
+
+Docs/Comms
+- [x] env-variables: reference `--vm-backend`, `HAKO_LLVM_USE_HARNESS`, `HAKO_C_ABI_ALLOC`
+- [ ] migration notes: prefer harness; inkwell legacy; rollback path
+
+Tests/Smokes
+- [ ] quick stays green (default). No noise banners unless path used.
+- [ ] opt-in smoke: inkwell banner visible when feature path chosen
--- a/docs/private/roadmap/phases/phase-20.26/PLAN.md
+++ b/docs/private/roadmap/phases/phase-20.26/PLAN.md
@ -0,0 +1,54 @@
+# Phase 20.26 — Final Rust Consolidation + hakmem (Plan)
+
+Purpose
+- Consolidate remaining Rust lines to Floor-only responsibilities and move legacy backends to archive with deprecations.
+- Keep day-to-day defaults unchanged and green; all flips are opt-in and guarded.
+
+Scope (Phase 20.26)
+- Deprecate and archive legacy Rust LLVM (inkwell) backend; prefer ny-llvmc (llvmlite harness).
+- Keep Rust as Floor (CLI, I/O, process, FFI) and shift decision/normalization to Hakorune boxes where feasible.
+- Add small helper gates for memory (hakmem) without changing defaults.
+
+Non-Goals
+- No default behavior changes for users. No removal of legacy code without a full deprecation window (1 release).
+- No broad refactor of working paths outside agreed guardrails.
+
+Workstreams
+1) Deprecation warnings (inkwell)
+   - Print a one-time deprecate banner when feature `llvm-inkwell-legacy` path executes.
+   - Docs: mark inkwell as legacy and point to ny-llvmc.
+
+2) Archive and gate (inkwell)
+   - Move `src/backend/llvm/compiler/**` → `archive/legacy/llvm-inkwell/**` (paths preserved via `#[path]` when feature active).
+   - Keep feature gates and tests green; no behavior change.
+
+3) Runner plan adoption (thin)
+   - Introduce `RunnerPlanBuilder` in lang: build a plan (decision only). Rust applies the plan.
+   - Start as opt-in (`HAKO_RUNNER_PLAN=1`), no behavior change by default.
+   - v0: action ExecuteCore/ExecuteVM を適用（Gate‑C/VM）。ExecuteNyLlvmc/Boxes は advisory（将来拡張）。
+
+4) hakmem integration (gate only)
+   - Keep libc as default allocator. Provide `--mem hakmem`/`HAKO_C_ABI_ALLOC=hakmem` placeholder route.
+   - No functional switch yet; only routing and docs.
+
+Milestones
+- M1 (A): Deprecation banner + docs scaffold + CURRENT_TASK updated
+- M2 (B): Archive move, feature-gated paths compile; quick stays green
+- M3 (C): RunnerPlan opt-in wiring; no default change
+- M4 (D): hakmem gate documented and observed (no default flip)
+
+Risks & Mitigations
+- Risk: Path drift between archived code and callers → Mitigate with `#[path]` glue and feature tests.
+- Risk: Surprise behavior changes → Keep all flips opt-in; add stable tags; Fail-Fast on ambiguity.
+
+Toggles (ENV/CLI)
+- `--vm-backend llvm|vm|mir` (ENV: `HAKO_VM_BACKEND`) — unchanged
+- `HAKO_LLVM_USE_HARNESS=1` — prefer ny-llvmc harness path
+- `HAKO_C_ABI_ALLOC={libc|hakmem}` — allocator gate (default: libc)
+- `HAKO_RUNNER_PLAN=1` — opt-in RunnerPlan path (decision in lang; v0 は ExecuteCore/ExecuteVM のみ適用)
+
+Acceptance (Phase 20.26 complete)
+- quick/integration green with defaults unchanged
+- inkwell path prints deprecate banner when used; harness path preferred in docs
+- legacy LLVM code archived and feature-gated; build remains green
+- docs updated (README/PLAN/CHECKLIST, env toggles, migration notes)
--- a/docs/private/roadmap/phases/phase-20.26/README.md
+++ b/docs/private/roadmap/phases/phase-20.26/README.md
@ -0,0 +1,656 @@
+# Phase 20.26 — Final Rust Consolidation + hakmem Integration
+
+**期間**: 2-3ヶ月
+**ステータス**: 計画更新（Rust Floor方針に整合）
+**前提条件**: Phase 20.25（Box System + MIR Builder削除）完了
+
+---
+
+## 🎯 Executive Summary
+
+**Purpose**: Rust 層を最終整理し、hakmem アロケータ統合で完全セルフホスト達成。
+
+**Final Goal**: **Rust = Floor, Hakorune = House** 完全実現
+
+### Target State
+
+```
+┌────────────────────────────────────────────────┐
+│ Rust Layer (≤5,000 lines - absolute minimum)   │
+│                                                 │
+│ ┌─────────────────────────────────────┐        │
+│ │ HostBridge API (~500 lines)         │        │
+│ │ - Hako_RunScriptUtf8                │        │
+│ │ - Hako_Retain / Hako_Release        │        │
+│ │ - Hako_ToUtf8 / Hako_LastError      │        │
+│ └─────────────────────────────────────┘        │
+│                                                 │
+│ ┌─────────────────────────────────────┐        │
+│ │ CLI Minimal (~1,000 lines)          │        │
+│ │ - Argument parsing                  │        │
+│ │ - Backend selection                 │        │
+│ │ - Environment setup                 │        │
+│ └─────────────────────────────────────┘        │
+│                                                 │
+│ ┌─────────────────────────────────────┐        │
+│ │ hakmem C-ABI Binding (~500 lines)   │        │
+│ │ - LD_PRELOAD integration            │        │
+│ │ - Memory allocator interface        │        │
+│ └─────────────────────────────────────┘        │
+│                                                 │
+│ ┌─────────────────────────────────────┐        │
+│ │ Essential Data Structures           │        │
+│ │ (~3,000 lines - MIR types only)     │        │
+│ └─────────────────────────────────────┘        │
+└────────────────────────────────────────────────┘
+```
+
+### Targets（-61,713行、段階的アーカイブ後の削減）
+
+```
+From Phase 20.25 end state:  66,713 lines
+
+Delete:
+├── src/mir/ (except essential)  -6,835 lines  ← Keep only core types
+├── src/backend/llvm/            -6,551 lines  ← Experimental, remove
+├── src/backend/wasm/              -200 lines  ← Experimental, remove
+├── src/cli/ (minimize)          -4,000 lines  ← Keep minimal (~1,000)
+├── src/runner/ (minimize)       -2,500 lines  ← Keep minimal (~500)
+├── src/plugin_system/          -10,000 lines  ← Hakorune plugin system
+├── src/kernel/                  -8,000 lines  ← Hakorune kernel
+├── src/other/ (cleanup)        -23,627 lines  ← Various dead code
+────────────────────────────────────────────────
+Total deleted:                  -61,713 lines
+
+Final Rust layer:                ~5,000 lines ✅
+```
+
+**Cumulative Progress**:
+- Phase 20.24: -10,500 lines（-9.0%）
+- Phase 20.25: -22,193 lines（-19.0%）
+- Phase 20.26: -61,713 lines（-52.8%）
+- **Total**: **-94,406 lines（-80.8%）** 🔥
+
+**Final State**: **Rust (Floor): ≤5,000 / Hakorune (House): 50,000+** = **True Self‑Hosting**
+
+---
+
+## 🏗️ Implementation Roadmap
+
+### Month 1: Rust Layer Audit & Consolidation
+
+#### Week 1: Comprehensive Audit
+
+**Goal**: 全 Rust ファイルを分類（Keep / Delete / Minimize）
+
+**Audit Categories**:
+
+```
+Category 1: KEEP (Essential - ~3,000 lines)
+├── src/mir/types.rs             ~600 lines  ← MirType, ConstValue
+├── src/mir/instruction.rs       ~800 lines  ← MirInstruction enum
+├── src/mir/basic_block.rs       ~470 lines  ← BasicBlock
+├── src/mir/function.rs          ~564 lines  ← MirModule, MirFunction
+└── src/mir/value.rs             ~400 lines  ← Register, Value types
+
+Category 2: MINIMIZE (Reduce to ~2,000 lines)
+├── src/cli/                   5,000 → 1,000  ← -4,000
+├── src/runner/                3,000 →   500  ← -2,500
+├── src/c_abi/                 2,000 → 500    ← -1,500 (consolidate)
+
+Category 3: DELETE (Experimental/Dead - ~56,713 lines)
+├── src/backend/llvm/          -6,551 lines  ← Python llvmlite primary
+├── src/backend/wasm/            -200 lines  ← Python llvmlite WASM
+├── src/plugin_system/        -10,000 lines  ← Hakorune plugin system
+├── src/kernel/                -8,000 lines  ← Hakorune kernel
+├── src/verification/          -2,000 lines  ← Hakorune verifier
+├── src/json/                  -1,500 lines  ← serde_json sufficient
+├── src/error/                 -1,200 lines  ← Minimal error handling
+├── src/debug/                 -1,800 lines  ← Hakorune debug tools
+├── src/config/                -1,000 lines  ← Env vars sufficient
+├── src/metrics/               -1,500 lines  ← Hakorune metrics
+├── src/testing/               -2,000 lines  ← Smoke tests external
+├── src/utils/                 -1,500 lines  ← Minimal utils
+├── src/macros/                  -800 lines  ← No longer needed
+└── src/other/                -18,662 lines  ← Various dead code
+```
+
+**Tasks**:
+- [ ] Audit ALL files in `src/`（108 files from comprehensive roadmap）
+- [ ] Classify each file: Keep / Delete / Minimize
+- [ ] Identify dependencies: What depends on what?
+- [ ] Create deletion plan with safe order
+
+**Deliverable**: `RUST_LAYER_AUDIT.md` - 完全なファイルリスト＋分類
+
+#### Week 2: Dependency Graph Analysis
+
+**Goal**: 安全な削除順序を決定
+
+**Dependency Analysis**:
+```bash
+# Tool: cargo-tree, cargo-geiger, etc.
+cargo tree --all-features --depth 3 > dependency_tree.txt
+
+# Custom analysis
+rg "use crate::" src/ | sort | uniq > internal_dependencies.txt
+
+# Identify circular dependencies
+# Identify orphaned files (no incoming edges)
+```
+
+**Output**: Dependency graph（Graphviz DOT format）
+
+```dot
+digraph RustDependencies {
+  // Essential (keep)
+  MirTypes [color=green];
+  MirInstruction [color=green];
+
+  // Minimize
+  CLI [color=yellow];
+  Runner [color=yellow];
+
+  // Delete
+  LLVM [color=red];
+  PluginSystem [color=red];
+
+  // Dependencies
+  CLI -> MirTypes;
+  Runner -> MirTypes;
+  LLVM -> MirTypes;  // Can delete, MirTypes stays
+}
+```
+
+**Tasks**:
+- [ ] Generate full dependency graph
+- [ ] Identify deletion candidates（no internal dependencies）
+- [ ] Plan deletion wave order（Wave 1, 2, 3...）
+
+#### Week 3-4: Wave 1 Deletion（Experimental Backends）
+
+**Target**: `src/backend/llvm/`, `src/backend/wasm/`
+
+**Rationale**:
+- Python llvmlite is primary LLVM backend（218,056 lines, proven）
+- Rust inkwell is experimental（6,551 lines, incomplete）
+- WASM via llvmlite works（Phase 15.8 complete）
+
+**Deletion**:
+```bash
+# Safety first
+git tag phase-20.26-wave1-pre
+git branch backup/rust-llvm-backend
+
+# Delete
+rm -rf src/backend/llvm/   # -6,551 lines
+rm -rf src/backend/wasm/   # -200 lines
+```
+
+**Impact Analysis**:
+- CLI: `--backend llvm` flag → `--backend llvm-py`（Python llvmlite）
+- Tests: Update smoke tests to use Python backend
+- Docs: Update backend documentation
+
+**Tasks**:
+- [ ] Update CLI backend selection
+- [ ] Remove `--backend llvm` flag（Rust inkwell）
+- [ ] Update all smoke tests
+- [ ] Full regression testing
+
+**Acceptance**:
+- [ ] All smoke tests PASS（296/296）
+- [ ] LLVM backend via Python works
+- [ ] No references to deleted code
+
+---
+
+### Month 2: Plugin System & Kernel Deletion
+
+#### Week 1-2: Plugin System Migration
+
+**Current Rust Plugin System**（~10,000 lines）:
+```
+src/plugin_system/
+├── registry.rs          ~1,500 lines  ← Plugin discovery
+├── loader.rs            ~2,000 lines  ← Dynamic loading
+├── handle.rs            ~1,200 lines  ← Handle management
+├── abi.rs               ~1,800 lines  ← C-ABI bridge
+├── lifecycle.rs         ~1,000 lines  ← Init/shutdown
+└── ... (other)          ~2,500 lines
+```
+
+**Hakorune Plugin System**（完全実装済み）:
+```
+lang/src/runtime/plugin/
+├── plugin_registry_box.hako
+├── plugin_loader_box.hako
+├── handle_registry_box.hako
+└── ...
+```
+
+**Migration Strategy**:
+```rust
+// Minimal Rust wrapper for Hakorune plugin system
+
+pub struct PluginSystemShim {
+    hakorune_registry: HakoHandle,  // Points to Hakorune PluginRegistryBox
+}
+
+impl PluginSystemShim {
+    pub fn load_plugin(&self, path: &str) -> Result<()> {
+        // Call Hakorune plugin system
+        let result = call_hakorune(
+            "PluginRegistryBox.load_plugin",
+            &[path.into()]
+        )?;
+        Ok(())
+    }
+}
+```
+
+**Tasks**:
+- [ ] Implement PluginSystemShim（~200 lines）
+- [ ] Replace all calls: `plugin_system::load()` → `PluginSystemShim::load_plugin()`
+- [ ] Test with existing plugins（StringBox, ArrayBox, etc.）
+- [ ] Delete `src/plugin_system/`（-10,000 lines）
+
+#### Week 3-4: Kernel Deletion
+
+**Current Rust Kernel**（~8,000 lines）:
+```
+src/kernel/
+├── runtime.rs           ~2,000 lines  ← Runtime initialization
+├── scheduler.rs         ~1,500 lines  ← Task scheduling
+├── memory.rs            ~1,200 lines  ← Memory management
+├── io.rs                ~1,000 lines  ← I/O subsystem
+└── ... (other)          ~2,300 lines
+```
+
+**Hakorune Kernel**（完全実装済み）:
+```
+lang/src/runtime/kernel/
+├── runtime_box.hako
+├── scheduler_box.hako
+├── memory_manager_box.hako
+└── ...
+```
+
+**Migration Strategy**: Same as Plugin System（Minimal shim）
+
+**Tasks**:
+- [ ] Implement KernelShim（~300 lines）
+- [ ] Replace kernel calls
+- [ ] Test runtime initialization
+- [ ] Delete `src/kernel/`（-8,000 lines）
+
+---
+
+### Month 3: hakmem Integration + Final Cleanup
+
+#### Week 1-2: hakmem Allocator Integration
+
+**Goal**: Hakorune uses hakmem as default allocator（no libc malloc）
+
+**Current State**（Phase 6.14 完了）:
+- ✅ hakmem PoC complete（6,541 lines C）
+- ✅ mimalloc parity achieved（json: +36.4%, mir: -18.8%）
+- ✅ Call-site profiling working
+- ✅ UCB1 evolution ready
+
+**Integration Strategy**:
+
+```c
+// src/c_abi/hakmem_binding.c (NEW - ~200 lines)
+
+#include "hakmem.h"  // From apps/experiments/hakmem-poc/
+
+// Override libc malloc/free
+void* malloc(size_t size) {
+    return hak_alloc_cs(size);
+}
+
+void free(void* ptr) {
+    hak_free_cs(ptr, 0);  // Size unknown, hakmem infers from header
+}
+
+void* realloc(void* ptr, size_t new_size) {
+    void* new_ptr = malloc(new_size);
+    if (ptr) {
+        memcpy(new_ptr, ptr, /* old_size */);
+        free(ptr);
+    }
+    return new_ptr;
+}
+```
+
+**Build Integration**:
+```bash
+# Cargo.toml
+[dependencies]
+hakmem = { path = "apps/experiments/hakmem-poc" }
+
+[profile.release]
+# Use hakmem instead of system allocator
+```
+
+**Tasks**:
+- [ ] Create `src/c_abi/hakmem_binding.c`
+- [ ] Integrate hakmem into Cargo build
+- [ ] Test with `LD_PRELOAD=libhakmem.so`
+- [ ] Benchmark: Before vs After（memory usage, performance）
+
+**Acceptance**:
+- [ ] All allocations go through hakmem（verify with profiling）
+- [ ] No libc malloc calls（verify with `nm` or `ldd`）
+- [ ] Performance: ±10% of libc malloc
+- [ ] Memory usage: ±10% of libc malloc
+
+#### Week 3: Final Cleanup
+
+**Target**: Delete all remaining dead code（~23,627 lines）
+
+**Cleanup Categories**:
+```
+1. Dead imports (no longer used)
+2. Dead functions (no callers)
+3. Dead tests (functionality moved to Hakorune)
+4. Dead docs (outdated architecture)
+5. Dead examples (superseded)
+```
+
+**Tools**:
+```bash
+# Find unused functions
+cargo +nightly rustc -- -Z print=dead-code
+
+# Find unused dependencies
+cargo machete
+
+# Find orphaned files
+find src/ -name "*.rs" | while read f; do
+  grep -r "$(basename $f .rs)" src/ | grep -v "^$f:" || echo "Orphaned: $f"
+done
+```
+
+**Tasks**:
+- [ ] Run dead code analysis
+- [ ] Delete identified dead code
+- [ ] Clean imports（remove unused `use` statements）
+- [ ] Update Cargo.toml（remove unused dependencies）
+
+#### Week 4: Final Verification & Documentation
+
+**Verification**:
+```bash
+# Clean build
+cargo clean
+cargo build --release
+
+# Size check
+ls -lh target/release/hakorune
+# Expected: ~5MB（was ~15MB before cleanup）
+
+# Line count
+cloc src/
+# Expected: ~5,000 lines Rust
+
+# Full test suite
+tools/smokes/v2/run.sh --profile all
+# Expected: 296/296 PASS
+
+# Performance benchmark
+tools/bench_unified.sh --backend all --warmup 10 --repeat 50
+# Expected: No regression（±5%）
+```
+
+**Documentation**:
+- [ ] Architecture diagram（Final state）
+- [ ] Rust layer API reference（minimal surface）
+- [ ] hakmem integration guide
+- [ ] Migration complete announcement
+
+---
+
+## ✅ 受け入れ基準（Acceptance Criteria）
+
+### Quantitative Goals
+
+- [ ] **Rust layer**: ≤5,000 lines（目標達成: 99.5% → 実際: 80.8% 削減）
+- [ ] **Hakorune layer**: 50,000+ lines（Compiler + VM + Boxes + Plugin System）
+- [ ] **Binary size**: ≤5MB（15MB → 5MB, -67%）
+- [ ] **Build time**: ≤30秒（Clean build, release mode）
+
+### Functional Requirements
+
+- [ ] **All smoke tests PASS**: 296/296
+- [ ] **Self-compilation works**: Hako₁ → Hako₂ → Hako₃（bit-identical）
+- [ ] **hakmem default**: No libc malloc usage
+- [ ] **Performance parity**: ±10% vs Phase 20.25 end state
+
+### Quality Requirements
+
+- [ ] **No dead code**: `cargo +nightly rustc -Z print=dead-code` clean
+- [ ] **No unused dependencies**: `cargo machete` clean
+- [ ] **Documentation complete**: Architecture, API, Migration guide
+- [ ] **CI passing**: All checks green
+
+### Safety Requirements
+
+- [ ] **Rollback tested**: Each month has checkpoint（tag + branch）
+- [ ] **Memory safety**: valgrind clean with hakmem
+- [ ] **Thread safety**: TSan clean（if applicable）
+
+---
+
+## 🚨 Risk Analysis
+
+### Critical Risks
+
+| リスク | 確率 | 影響 | 軽減策 |
+|--------|------|------|--------|
+| **hakmem stability** | 中 | 高 | Extensive testing, fallback to libc |
+| **Dependency hell** | 中 | 中 | Wave-based deletion, dependency graph |
+| **Dead code resurgence** | 低 | 低 | CI checks for unused code |
+| **Performance regression** | 低 | 中 | Continuous benchmarking |
+| **Rollback complexity** | 中 | 高 | Monthly checkpoints, granular commits |
+
+### hakmem Integration Risks（Most Critical）
+
+**Risk**: hakmem has bugs or performance issues in production
+
+**Impact**: High（all allocations affected）
+
+**Mitigation**:
+1. **Extensive testing**: Run all smoke tests with hakmem
+2. **Benchmarking**: Compare vs libc malloc（should be ±10%）
+3. **Fallback mechanism**:
+   ```rust
+   pub fn get_allocator() -> Allocator {
+       match env::var("HAKO_USE_HAKMEM") {
+           Ok(val) if val == "0" => Allocator::Libc,
+           _ => Allocator::Hakmem,  // Default
+       }
+   }
+   ```
+4. **Memory profiling**: valgrind, ASan validation
+5. **Production rollout**: Gradual（dev → staging → prod）
+
+---
+
+## 📈 Timeline Visualization
+
+```
+Month 1: Rust Layer Audit & Wave 1 Deletion
+├─ Week 1:   Comprehensive audit         [████░░░░] File classification
+├─ Week 2:   Dependency graph            [████░░░░] Safe deletion order
+├─ Week 3-4: Wave 1（LLVM/WASM backend） [████████] -6,751 lines
+└─ Checkpoint: Experimental backends removed
+
+Month 2: Plugin System & Kernel Deletion
+├─ Week 1-2: Plugin System migration     [████████] -10,000 lines
+├─ Week 3-4: Kernel migration            [████████] -8,000 lines
+└─ Checkpoint: Core systems on Hakorune
+
+Month 3: hakmem Integration + Final Cleanup
+├─ Week 1-2: hakmem integration          [████░░░░] Default allocator
+├─ Week 3:   Final cleanup               [████████] -23,627 lines
+├─ Week 4:   Verification & docs         [████░░░░] ✅ Complete
+└─ Completion: Phase 20.26 done
+
+Total: 2-3 months, -61,713 lines (-52.8%)
+Cumulative: -94,406 lines (-80.8%) from Phase 20.24 start
+```
+
+---
+
+## 💡 Strategic Insights
+
+### Achievement Summary
+
+**Before Phase 20.24**（Starting point）:
+```
+Total codebase:     116,841 lines
+Rust layer (src/):   99,406 lines (85.1%)
+Hakorune layer:      17,435 lines (14.9%)
+```
+
+**After Phase 20.26**（Final state）:
+```
+Total codebase:      ~60,000 lines
+Rust layer (src/):   ~5,000 lines (8.3%) ✅
+Hakorune layer:     ~55,000 lines (91.7%) ✅
+
+Rust reduction: -94,406 lines (-95.0%) 🔥
+Ratio flip: 85% Rust → 8% Rust ⚡
+```
+
+### Key Milestones
+
+| Phase | Duration | Lines Deleted | Cumulative | Key Achievement |
+|-------|----------|---------------|------------|-----------------|
+| **20.23** | 2-3 weeks | -0 | -0 | Arc/RefCell foundation（Hakorune実装） |
+| **20.24** | 1-2 months | -10,500 | -10,500 | Parser 完全削除 |
+| **20.25** | 2-3 months | -22,193 | -32,693 | MIR Builder + VM + Box System 削除 |
+| **20.26** | 2-3 months | -61,713 | -94,406 | **Final consolidation** ✅ |
+| **Total** | **6-9 months** | **-94,406** | **-94,406** | **95% Rust reduction** 🔥 |
+
+### Comparison with Original Estimates
+
+**Original Plan**（from comprehensive roadmap）:
+- Bridge-B Path: 14.3% reduction（-16,693 lines）in 7-14 months
+- C ABI Path: 86-93% reduction（-50,000+ lines）in 12-18 months
+
+**This Plan（Hakorune Implementation）**:
+- **95.0% reduction**（-94,406 lines）in **6-9 months** ✅
+- **10% faster** than C ABI path
+- **Lower risk**（Hakorune > C for logic）
+
+**Why This Plan Succeeds**:
+1. **Hakorune for logic**（Arc/RefCell, Box System）
+2. **C for data operations**（hakmem, atomic ops）
+3. **Proven pattern**（GcBox precedent）
+4. **Incremental approach**（4 phases, monthly checkpoints）
+
+---
+
+## 🔗 関連ドキュメント
+
+- **Phase 20.23**: [Arc/RefCell in Hakorune](../phase-20.23/README.md)
+- **Phase 20.24**: [Parser削除](../phase-20.24/README.md)
+- **Phase 20.25**: [Box System + MIR Builder削除](../phase-20.25/README.md)
+- **hakmem**: [apps/experiments/hakmem-poc/](../../../../apps/experiments/hakmem-poc/)
+- **Rust Removal Roadmap**: [rust-removal-comprehensive-roadmap.md](../../../development/analysis/rust-removal-comprehensive-roadmap.md)
+
+---
+
+## 🎉 Final Outcome
+
+### Before (Phase 20.23 start)
+
+```
+┌────────────────────────────────────────────────┐
+│ Rust Layer: 99,406 lines (85.1%)               │
+│ ├── Parser/AST (10,500)                        │
+│ ├── MIR Builder/Optimizer (3,800)              │
+│ ├── Rust VM (2,393)                            │
+│ ├── Box System (16,000)                        │
+│ ├── LLVM/WASM backends (6,751)                 │
+│ ├── Plugin System (10,000)                     │
+│ ├── Kernel (8,000)                             │
+│ └── Other (41,962)                             │
+└────────────────────────────────────────────────┘
+
+Hakorune Layer: 17,435 lines (14.9%)
+```
+
+### After (Phase 20.26 complete)
+
+```
+┌────────────────────────────────────────────────┐
+│ Rust Layer: ~5,000 lines (8.3%) ✅             │
+│ ├── HostBridge API (~500)                      │
+│ ├── CLI Minimal (~1,000)                       │
+│ ├── hakmem Binding (~500)                      │
+│ └── Essential MIR Types (~3,000)               │
+└────────────────────────────────────────────────┘
+
+┌────────────────────────────────────────────────┐
+│ Hakorune Layer: ~55,000 lines (91.7%) ✅       │
+│ ├── Compiler (Parser + MIR Builder) (~12,000)  │
+│ ├── VM (MiniVmBox) (~5,000)                    │
+│ ├── Box System (All boxes) (~15,000)           │
+│ ├── Plugin System (~5,000)                     │
+│ ├── Kernel (~5,000)                            │
+│ ├── Standard Library (~10,000)                 │
+│ └── Other (~3,000)                             │
+└────────────────────────────────────────────────┘
+
+hakmem (C): 6,541 lines (Memory allocator)
+```
+
+**Key Metrics**:
+- **Rust**: 99,406 → 5,000 lines（**-95.0%** 🔥）
+- **Hakorune**: 17,435 → 55,000 lines（**+215.4%** ⚡）
+- **Total**: 116,841 → 66,541 lines（-43.0%）
+- **Ratio**: 85% Rust → **8% Rust**（**Rust = Floor** ✅）
+
+---
+
+## 🏆 Final Achievement
+
+**True Self-Hosting Realized**:
+
+```
+✅ Rust = Floor（~5,000 lines - minimal foundation）
+✅ Hakorune = House（~55,000 lines - everything）
+✅ hakmem = Plumbing（~6,500 lines C - memory）
+
+Ratio: 1 : 11 : 1.3 (Rust : Hakorune : C)
+```
+
+**What Rust Does**（Floor responsibilities）:
+1. HostBridge API（C-ABI entry points）
+2. CLI Minimal（Argument parsing）
+3. hakmem Binding（Allocator integration）
+4. Essential Types（MIR data structures - shared by all backends）
+
+**What Hakorune Does**（House - everything else）:
+1. Compiler（Parser + MIR Builder + Optimizer）
+2. VM（MiniVmBox - interpreter）
+3. Box System（StringBox, ArrayBox, MapBox, etc.）
+4. Plugin System（Dynamic loading）
+5. Kernel（Runtime, Scheduler, Memory Manager）
+6. Standard Library（All builtins）
+
+**What C Does**（Plumbing）:
+1. hakmem（Memory allocator with call-site profiling）
+2. Arc/RefCell atomic operations（Data plane）
+3. System calls（mmap, munmap, etc.）
+
+---
+
+**ステータス**: 未開始
+**開始可能条件**: Phase 20.25（Box System + MIR Builder削除）完了
+**期間**: 2-3ヶ月（8-12週間）
+**Complete**: ✅ **True Self-Hosting Achieved** - Rust = Floor, Hakorune = House