hakorune/docs/development/current/main/PHASE_57_SUMMARY.md

# Phase 57: OWNERSHIP-ANALYZER-DEV - Summary

## Status: ✅ COMPLETED

**Date**: 2025-12-12
**Duration**: Single session implementation
**Test Results**: All 946 tests passing (56 ignored)

## What Was Implemented

### 1. Naming SSOT Fix
- Unified naming: `owned_vars` (code) vs `owned_carriers` (docs)
- Decision: Keep `owned_vars` in code (more general - includes read-only owned)
- Updated all documentation to use `owned_vars` consistently

### 2. Core Analyzer Implementation
Created `/home/tomoaki/git/hakorune-selfhost/src/mir/join_ir/ownership/analyzer.rs`:
- **OwnershipAnalyzer**: Main analysis engine (420+ lines)
- **ScopeKind**: Function/Loop/Block/If scope types
- **ScopeInfo**: Internal scope representation with defined/reads/writes/condition_reads

### 3. Analysis Algorithm

#### Scope Tree Construction
- Function/Loop/Block/If each get unique ScopeId
- Parent-child relationships tracked via scope hierarchy
- Body-local ownership rule: `local` in if/block → enclosing Loop/Function owns it

#### Variable Collection (per scope)
- `defined`: Variables declared with `local` in this scope
- `reads`: All variable reads (including nested scopes)
- `writes`: All variable writes (including nested scopes)
- `condition_reads`: Variables read in loop/if conditions

#### Ownership Assignment
- `owned_vars` = variables defined in Loop/Function scopes
- Carriers = `owned_vars.filter(is_written == true)`
- Read-only owned variables are NOT carriers

#### Plan Generation
- `relay_writes` = writes - owned (find owner in ancestors)
- `captures` = reads - owned - writes (read-only captures)
- `condition_captures` = captures ∩ condition_reads

### 4. Key Implementation Decisions

#### Smart Propagation
Fixed issue where parent scopes were trying to relay variables owned by child Loop/Function scopes:
```rust
// Only propagate writes that are NOT locally owned by Loop/Function children
if child_kind == ScopeKind::Loop || child_kind == ScopeKind::Function {
    // Don't propagate writes for variables defined in this Loop/Function
    for write in writes {
        if !child_defined.contains(&write) {
            parent.writes.insert(write);
        }
    }
} else {
    // For If/Block, propagate all writes
    parent.writes.extend(writes);
}
```

#### Relay Path Construction
- Walk up ancestor chain to find owner
- Collect only Loop scopes in relay_path (skip If/Block)
- Inner loop → Outer loop → Function (relay chain)

#### Invariant Verification (debug builds only)
- No variable appears in multiple categories (owned/relay/capture)
- All relay_writes have valid owners
- condition_captures ⊆ captures

### 5. Comprehensive Test Suite
Implemented 4 test cases covering all major scenarios:

1. **test_simple_loop_ownership**: Basic loop with relay writes to function
2. **test_loop_local_carrier**: Loop-local variable (owned AND written)
3. **test_capture_read_only**: Read-only capture in loop condition
4. **test_nested_loop_relay**: Nested loops with relay chain

All tests pass ✅

### 6. Documentation Updates
- Updated `phase56-ownership-relay-design.md` with Phase 57 algorithm section
- Updated `mod.rs` to reflect Phase 57 completion status
- Clear separation: analyzer = dev-only, not connected to lowering yet

## Architecture Highlights

### Responsibility Boundary
**This module does**:
- ✅ Collect reads/writes from AST/ProgramJSON
- ✅ Determine variable ownership (owned/relay/capture)
- ✅ Produce OwnershipPlan for downstream lowering

**This module does NOT**:
- ❌ Generate MIR instructions
- ❌ Modify JoinIR structures
- ❌ Perform lowering transformations

### Core Invariants Enforced
1. **Ownership Uniqueness**: Each variable has exactly one owner scope
2. **Carrier Locality**: carriers = writes ∩ owned
3. **Relay Propagation**: writes to ancestor-owned → relay up
4. **Capture Read-Only**: captures have no PHI at this scope

## Files Changed

### New Files
- `/home/tomoaki/git/hakorune-selfhost/src/mir/join_ir/ownership/analyzer.rs` (420+ lines)

### Modified Files
- `/home/tomoaki/git/hakorune-selfhost/src/mir/join_ir/ownership/mod.rs` (export analyzer)
- `/home/tomoaki/git/hakorune-selfhost/docs/development/current/main/phase56-ownership-relay-design.md` (algorithm section)

## Test Results

```
running 7 tests
test mir::join_ir::ownership::analyzer::tests::test_capture_read_only ... ok
test mir::join_ir::ownership::types::tests::test_carriers_filter ... ok
test mir::join_ir::ownership::analyzer::tests::test_nested_loop_relay ... ok
test mir::join_ir::ownership::types::tests::test_invariant_verification ... ok
test mir::join_ir::ownership::analyzer::tests::test_loop_local_carrier ... ok
test mir::join_ir::ownership::analyzer::tests::test_simple_loop_ownership ... ok
test mir::join_ir::ownership::types::tests::test_empty_plan ... ok

test result: ok. 7 passed; 0 failed; 0 ignored
```

Full test suite: **946 tests passed, 0 failed, 56 ignored** ✅

## Next Steps (Phase 58+)

### Phase 58: P2 Plumbing (dev-only)
- Connect analyzer to Pattern 2 lowering
- Generate PHI instructions based on OwnershipPlan
- Test with P2 loops

### Phase 59: P3 Plumbing (dev-only)
- Connect analyzer to Pattern 3 lowering
- Handle relay chains in nested loops
- Test with P3 loops

### Phase 60: Cleanup Dev Heuristics
- Remove old carrier detection logic
- Switch to OwnershipPlan throughout

### Phase 61: Canonical Promotion Decision
- Finalize promotion strategy
- Production rollout

## Design Philosophy

### "読むのは自由、管理は直下だけ" (Read Freely, Manage Directly)
- Variables can be READ from anywhere (capture)
- Variables can only be WRITTEN by their owner or via relay
- Ownership is determined by definition scope (body-local rule)
- No shadowing complexity - clear ownership hierarchy

### Dev-First Approach
- Implemented as pure analysis module first
- Not yet connected to lowering (no behavioral changes)
- Can be tested independently with JSON input
- Safe to merge without affecting existing code paths

## References
- **Phase 56 Design**: [phase56-ownership-relay-design.md](phase56-ownership-relay-design.md)
- **JoinIR Architecture**: [joinir-architecture-overview.md](joinir-architecture-overview.md)
- **Phase 43/245B**: Normalized JoinIR completion
- **ChatGPT Discussion**: 「読むのは自由、管理は直下だけ」設計

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**Implementation Status**: ✅ Phase 57 Complete - Ready for Phase 58 plumbing