# Phase 74: BindingId Infrastructure - Completion Checklist

## Implementation Checklist ✅

### Core Files
- [x] **`src/mir/binding_id.rs`** created
  - [x] `BindingId(u32)` struct with overflow protection
  - [x] `new()`, `next()`, `raw()` methods
  - [x] `Display` trait implementation
  - [x] 5 unit tests (creation, next, display, ordering, overflow)

- [x] **`src/mir/mod.rs`** updated
  - [x] Added `pub mod binding_id;`
  - [x] Re-exported `pub use binding_id::BindingId;`

- [x] **`src/mir/builder.rs`** extended
  - [x] `next_binding_id: u32` field added
  - [x] `binding_map: BTreeMap<String, BindingId>` field added
  - [x] `allocate_binding_id()` method implemented
  - [x] Initialization in `MirBuilder::new()`
  - [x] 4 unit tests added (initialization, sequential, shadowing, parallel)

- [x] **`src/mir/builder/vars/lexical_scope.rs`** updated
  - [x] `restore_binding: BTreeMap<String, Option<BindingId>>` field added to `LexicalScopeFrame`
  - [x] `pop_lexical_scope()` restores binding_map
  - [x] `declare_local_in_current_scope()` allocates BindingIds

### Documentation
- [x] **`docs/development/current/main/phase74-bindingid-infrastructure.md`**
  - [x] Architecture (ValueId vs BindingId)
  - [x] Implementation details
  - [x] Test strategy
  - [x] Next steps (Phase 75-77)

- [x] **`docs/development/current/main/PHASE_74_SUMMARY.md`**
  - [x] Implementation summary
  - [x] Test results
  - [x] Key design decisions

- [x] **`docs/development/current/main/phase74-checklist.md`** (this file)

---

## Test Results ✅

### Unit Tests (9 total)
```bash
$ cargo test --lib binding_id
test mir::binding_id::tests::test_binding_id_creation ... ok
test mir::binding_id::tests::test_binding_id_next ... ok
test mir::binding_id::tests::test_binding_id_display ... ok
test mir::binding_id::tests::test_binding_id_ordering ... ok
test mir::binding_id::tests::test_binding_id_overflow - should panic ... ok
test mir::builder::binding_id_tests::test_binding_map_initialization ... ok
test mir::builder::binding_id_tests::test_binding_allocation_sequential ... ok
test mir::builder::binding_id_tests::test_shadowing_binding_restore ... ok
test mir::builder::binding_id_tests::test_valueid_binding_parallel_allocation ... ok

test result: ok. 9 passed; 0 failed; 0 ignored
```

### Regression Tests
```bash
$ cargo test --release --lib
test result: ok. 958 passed; 0 failed; 56 ignored

$ cargo test --features normalized_dev --test normalized_joinir_min
test result: ok. 54 passed; 0 failed; 0 ignored
```

### Build Success
```bash
$ cargo build --lib
Finished `dev` profile [unoptimized + debuginfo] target(s) in 12.76s
```

---

## Acceptance Criteria ✅

| Criterion | Status | Evidence |
|-----------|--------|----------|
| `cargo build --lib` succeeds | ✅ | Compiled without errors |
| `cargo test --release --lib` passes | ✅ | 958 tests passed |
| `cargo test --features normalized_dev --test normalized_joinir_min` passes | ✅ | 54 tests passed |
| New tests all pass | ✅ | 9/9 BindingId tests passed |
| No production impact | ✅ | Infrastructure-only, no behavior changes |
| Phase 73 PoC structure replicated | ✅ | Same design as PoC, integrated into main |

---

## Design Validation ✅

### Architecture Principles
- [x] **Parallel Allocation**: ValueId and BindingId independent
- [x] **Determinism**: BTreeMap used (Phase 25.1 consistency)
- [x] **Symmetric Restoration**: Both maps restored on scope exit
- [x] **Overflow Protection**: debug_assert! checks in critical paths

### Phase 73 Compatibility
- [x] BindingId type matches PoC design
- [x] `allocate_binding_id()` API matches PoC
- [x] Lexical scope integration matches PoC
- [x] Test strategy follows PoC validation

---

## Code Quality ✅

### Documentation
- [x] All public APIs documented
- [x] Architecture overview written
- [x] Examples provided
- [x] Migration roadmap defined

### Testing
- [x] Unit tests for BindingId type
- [x] Integration tests for MirBuilder
- [x] Shadowing edge cases tested
- [x] Parallel allocation verified

### Code Style
- [x] Follows existing MirBuilder patterns
- [x] Consistent with Phase 25.1 BTreeMap usage
- [x] Clear variable names
- [x] Proper error messages

---

## Next Steps (Phase 75)

### Pilot Integration Planning
- [ ] Identify 1-2 candidate files for pilot usage
- [ ] Design logging strategy (e.g., `NYASH_BINDING_TRACE=1`)
- [ ] Create pilot smoke tests
- [ ] Document pilot integration approach

### Suggested Pilot Components
1. **`src/mir/builder/vars/`** - Local variable tracking (high shadowing frequency)
2. **`src/mir/builder/stmts.rs`** - Statement lowering (control flow + shadowing)

### Pilot Success Criteria
- [ ] BindingId used in 1-2 isolated components
- [ ] Logging shows correct BindingId allocation/restoration
- [ ] Smoke tests pass with pilot integration
- [ ] No behavior changes observed

---

## Commit Message Template

```
feat(mir): Phase 74 - BindingId infrastructure

Establish parallel BindingId allocation system alongside ValueId to support
future ScopeManager migration (Phase 75+).

Changes:
- Add src/mir/binding_id.rs (BindingId type + 5 tests)
- Extend MirBuilder with binding_map and allocate_binding_id()
- Update lexical_scope.rs for parallel restoration
- Add 4 integration tests in builder.rs
- Document architecture and migration roadmap

Test results:
- 9 new unit tests (all pass)
- 958 lib tests (no regressions)
- 54 normalized JoinIR tests (no regressions)

Phase 74 complete ✅ - Ready for Phase 75 pilot integration
```

---

## Sign-off

**Phase 74 Implementation**: ✅ Complete
**Test Coverage**: ✅ Full (9 unit + existing smoke)
**Documentation**: ✅ Comprehensive (~500 lines)
**Production Impact**: ✅ Zero (infrastructure-only)
**Ready for Phase 75**: ✅ Yes

---

**Date**: 2025-12-13
**Reviewer**: (awaiting review)
**Status**: Ready for integration
