Files
hakorune/docs/development/current/main/phase81-pattern2-exitline-contract.md
nyash-codex 9e32807a96 refactor(joinir): Phase 82-83 - Debug flag SSOT + Fallback verification
Phase 82: Centralized JoinIR debug flag reading
- Added is_joinir_debug() SSOT function in joinir_flags.rs
- Replaced 16 direct env::var() calls across 8 files
- Updated docs to recommend HAKO_JOINIR_DEBUG (NYASH_ deprecated)
- Backward compat: Both env vars work

Phase 83: Verified promoted carrier fallback behavior
- Confirmed NO fallback to name-based lookup for DigitPos/Trim
- Documented fallback expectations in Phase 80/81 docs
- Added verification commands and expected output

Changes:
- src/config/env/joinir_flags.rs: +187 lines (new SSOT module)
- 8 files: env var reads → is_joinir_debug() calls
- 3 docs: HAKO_JOINIR_DEBUG examples + fallback sections
- 1 summary doc: phase82-83-debug-flag-ssot-summary.md

Tests: 970/970 lib PASS, 58/58 normalized_dev PASS
Impact: Dev-only (zero production changes)
2025-12-13 19:01:14 +09:00

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# Phase 81: Pattern2 ExitLine Contract Stabilization
**Status**: Design Phase
**Created**: 2025-12-13
**Priority**: P1 (Blocking Phase 82+)
---
## Goal
Pattern2DigitPos/Trimの promoted carriers を含む ExitLine 接続契約を堅牢化し、E2E テストで安定性を固定する。
---
## Background
### Current Issue
Phase 74-80 で BindingId migration が完了し、Pattern2/3/4 で BindingId lookup が operational になった。しかし、Pattern2 の promoted carriersDigitPos/Trim パターンで生成される `is_digit_pos`, `is_ch_match` 等)の ExitLine 接続には以下の問題がある:
1. **ExitLine 接続タイミングの不確実性**:
- Promoted carriers は promoter が生成するが、ExitLine reconnection が適切に行われているか検証不足
- Exit PHI での promoted carriers の接続契約が明示されていない
2. **E2E テスト不足**:
- DigitPos パターン(`indexOf()` 使用)の E2E テストが不足
- Trim パターン(`skip_whitespace` 等)の E2E テストが不足
- 既存の `tests/phase246_json_atoi.rs` が Phase 80 完了後も安定していない可能性
3. **Contract 不明確**:
- Promoted carriers が ExitLine reconnection でどのように扱われるべきか不明確
- CarrierRole (LoopState vs ConditionOnly) による処理の違いが文書化されていない
### Symptoms
以下の症状が観測される可能性があるPhase 80 完了時点では未検証):
- `tests/phase246_json_atoi.rs` テスト失敗DigitPos pattern 使用)
- Exit PHI で promoted carriers が正しく接続されない
- ExitLine reconnection で ValueId が undefined になる
- ConditionOnly carriers が Exit PHI に含まれて不整合が起こる
---
## Reproduction
### Minimal Test Case
```rust
// DigitPos pattern with promoted carrier
local p = 0
local s = "123"
local sum = 0
loop(p < s.length()) {
local digit_pos = s.indexOf("0", p) // Promoted to is_digit_pos (ConditionOnly)
if digit_pos >= 0 { // Break condition uses promoted carrier
sum = sum + 1
}
p = p + 1
}
return sum
```
**Expected behavior**:
- `digit_pos``is_digit_pos` promotion succeeds
- `is_digit_pos` is ConditionOnly (not in exit_bindings)
- Exit PHI correctly includes `sum`, `p` (LoopState carriers)
- Exit PHI does NOT include `is_digit_pos` (ConditionOnly)
- Final result is correct
**Failure mode** (if contract violated):
- Exit PHI includes `is_digit_pos` → type mismatch or ValueId undefined
- Exit PHI missing `sum` or `p` → incorrect final result
- ExitLine reconnection fails → compilation error
---
## Invariants
### ExitLine Contract for Promoted Carriers
1. **CarrierRole Discrimination**:
- `LoopState` carriers: MUST be in exit_bindings, MUST have Exit PHI
- `ConditionOnly` carriers: MUST NOT be in exit_bindings, MUST NOT have Exit PHI
2. **Promoted Carrier Handling**:
- All promoted carriers have `CarrierVar.binding_id` set by CarrierBindingAssigner
- Promoted carriers follow same CarrierRole rules as non-promoted
- ExitMetaCollector includes all carriers (LoopState + ConditionOnly) for latch incoming
- ExitLineReconnector only processes LoopState carriers (skip ConditionOnly)
3. **ExitLine Reconnection Timing**:
- Promoted carriers are in CarrierInfo BEFORE ExitLine reconnection
- CarrierRole is determined BEFORE reconnection (via promoter)
- Reconnection uses CarrierRole to filter carriers
4. **BindingId Registration Completeness**:
- All LoopState carriers have BindingId registered in ConditionEnv
- ConditionOnly carriers may have BindingId registered (for condition lowering)
- Registration happens AFTER ValueId allocation, BEFORE condition lowering
---
## Design
### Verification Strategy
**Phase 81 focuses on verification, NOT new features.**
1. **Audit ExitLine Reconnection**:
- Verify `ExitLineReconnector` correctly skips ConditionOnly carriers
- Verify `ExitMetaCollector` includes all carriers for latch
- Verify exit_bindings filter is correct
2. **Add E2E Tests**:
- DigitPos pattern test (`indexOf()` with promoted `is_digit_pos`)
- Trim pattern test (`skip_whitespace` with promoted `is_ch_match`)
- Verify Exit PHI structure matches contract
3. **Document Contract**:
- Create SSOT for ExitLine + promoted carriers interaction
- Document CarrierRole-based filtering rules
- Link to existing Phase 78-80 BindingId docs
### Implementation Tasks
**Task 81-A: ExitLine Audit** (analysis only)
- Read `ExitLineReconnector` code
- Read `ExitMetaCollector` code
- Verify CarrierRole filtering is correct
- Document findings
**Task 81-B: E2E Tests** (high priority)
- Add DigitPos E2E test to `tests/normalized_joinir_min.rs`
- Add Trim E2E test to `tests/normalized_joinir_min.rs`
- Verify `tests/phase246_json_atoi.rs` passes (existing test)
- All tests dev-only (`#[cfg(feature = "normalized_dev")]`)
**Task 81-C: Contract Documentation** (medium priority)
- Update this doc with audit findings
- Create exit_line_promoted_carriers.md if needed
- Link from phase80-bindingid-p3p4-plan.md
**Task 81-D: Smoke Tests** (verification)
- Run `tools/smokes/v2/run.sh --profile quick`
- Verify no regressions in existing tests
- Document any failures
---
## Acceptance Criteria
### Minimum Requirements
1.**E2E Tests Pass**:
- `cargo test --release` includes DigitPos E2E test (PASS)
- `cargo test --release` includes Trim E2E test (PASS)
- `tests/phase246_json_atoi.rs` PASS
2.**Smoke Tests Pass**:
- `tools/smokes/v2/run.sh --profile quick` no regressions
- Existing Pattern2 tests continue to PASS
3.**Contract Documented**:
- ExitLine + promoted carriers contract documented
- CarrierRole filtering rules documented
- Audit findings recorded
### Success Metrics
- All lib tests PASS (970/970 baseline, +2 new E2E tests = 972/972)
- All smoke tests PASS (existing baseline)
- Zero production impact (dev-only tests)
- Contract clarity increased (documentation)
---
## Out of Scope
### Phase 81 does NOT include:
1. **New Features**:
- No new BindingId registration
- No new promoted carriers
- No changes to promotion logic
2. **Architecture Changes**:
- No ExitLine reconnection refactoring
- No CarrierRole enum changes
- No ConditionEnv API changes
3. **Pattern3/4 Work**:
- Phase 81 focuses on Pattern2 only
- Pattern3/4 ExitLine is out of scope
---
## Risk Assessment
### Low Risk:
- All changes are verification (tests + docs)
- No production code changes expected
- Audit is analysis-only
### Potential Issues:
1. **Existing Contract Violation**:
- If audit finds ExitLine currently violates contract → need fix
- Mitigation: Fix is localized, well-documented
2. **Test Failures**:
- If E2E tests fail → indicates real bug
- Mitigation: Fix bug, document root cause
3. **Smoke Test Regressions**:
- If quick smoke tests fail → need investigation
- Mitigation: Classify as Phase 81 target or out-of-scope
---
## References
### Related Documentation
- **Phase 80**: `phase80-bindingid-p3p4-plan.md` - BindingId P3/P4 expansion
- **Phase 78**: `phase78-bindingid-promoted-carriers.md` - CarrierBindingAssigner
- **Phase 77**: Implementation guide - DigitPos/Trim promoters
- **JoinIR Architecture**: `joinir-architecture-overview.md` - ExitLine/Boundary overview
### Key Code Files
- `src/mir/builder/control_flow/joinir/merge/exit_line_reconnector.rs` - ExitLine reconnection
- `src/mir/builder/control_flow/joinir/merge/exit_meta_collector.rs` - Exit metadata collection
- `src/mir/join_ir/lowering/carrier_info.rs` - CarrierVar, CarrierRole
- `src/mir/loop_pattern_detection/digitpos_detector.rs` - DigitPos detection
- `src/mir/loop_pattern_detection/trim_detector.rs` - Trim detection
### Test Files
- `tests/normalized_joinir_min.rs` - Add Phase 81 E2E tests here
- `tests/phase246_json_atoi.rs` - Existing DigitPos test (verify PASS)
---
## Next Steps
**After Phase 81 Complete**:
1. **Phase 82 (optional)**: Pattern3/4 carrier BindingId registration in後段
- Extend BindingId registration to carrier join_id determination points
- Reduce fallback usage further
2. **Phase 83 (optional)**: Debug flag cleanup
- Deprecate `NYASH_JOINIR_DEBUG` in favor of new naming
- Migrate tests to recommended env var
---
## Implementation Notes
### Task Ordering
Execute in this order:
1. Task 81-A (Audit) - Understand current state
2. Task 81-B (E2E Tests) - Verify contract
3. Task 81-D (Smoke Tests) - Regression check
4. Task 81-C (Documentation) - Record findings
### Commit Strategy
**Single commit** for Phase 81:
```
feat(joinir): Phase 81 - Pattern2 ExitLine contract verification (dev-only)
Task 81-A: ExitLine audit findings
- ExitLineReconnector correctly skips ConditionOnly carriers
- ExitMetaCollector includes all carriers for latch
- CarrierRole filtering verified correct
Task 81-B: E2E tests for promoted carriers
- test_phase81_digitpos_exitline_contract(): DigitPos pattern
- test_phase81_trim_exitline_contract(): Trim pattern
- Verified Exit PHI excludes ConditionOnly carriers
Task 81-D: Smoke test verification
- tools/smokes/v2/run.sh --profile quick PASS
- No regressions in existing tests
Task 81-C: Contract documentation
- ExitLine + promoted carriers contract documented
- CarrierRole filtering rules clarified
Tests: 972/972 PASS (970 baseline + 2 new E2E)
Smoke: quick profile PASS (no regressions)
Design: Verification-only, zero production impact
```
---
## Status Tracking
- [x] Task 81-A: ExitLine Audit (analysis) - **COMPLETE**
- [x] Task 81-B: E2E Tests (DigitPos + Trim) - **COMPLETE**
- [x] Task 81-C: Contract Documentation - **COMPLETE**
- [x] Task 81-D: Smoke Tests Verification - **COMPLETE**
**Current Phase**: Phase 81 Complete
**Next Action**: Commit Phase 81
---
## Task 81-A: Audit Findings
**Audit Date**: 2025-12-13
**Auditor**: Claude (AI Assistant)
**Status**: ✅ CONTRACT VERIFIED CORRECT
### Executive Summary
All ExitLine components correctly implement the CarrierRole contract:
-**ExitMetaCollector**: Includes ALL carriers (LoopState + ConditionOnly) in exit_bindings for latch incoming
-**ExitLineReconnector**: Skips ConditionOnly carriers for variable_map updates (only updates LoopState)
-**CarrierRole Filtering**: Implemented correctly in both components
-**Contract Compliance**: Full compliance with Phase 227-228 design
### Detailed Findings
#### 1. ExitMetaCollector Analysis
**File**: `src/mir/builder/control_flow/joinir/merge/exit_line/meta_collector.rs`
**Key Behavior** (lines 96-217):
```rust
// For each carrier in exit_meta.exit_values:
// 1. If in variable_map → create LoopExitBinding with LoopState role (default)
// 2. If NOT in variable_map:
// - If CarrierRole::ConditionOnly → Include in exit_bindings (host_slot=ValueId(0))
// - If CarrierRole::LoopState + FromHost → Include in exit_bindings (host_slot=ValueId(0))
// - If CarrierRole::LoopState + LoopLocalZero → Include in exit_bindings (host_slot=ValueId(0))
// - Otherwise → Skip (panic in strict mode)
```
**CarrierRole Handling** (lines 108-117):
```rust
let role = if let Some(ci) = carrier_info {
ci.carriers
.iter()
.find(|c| c.name == *carrier_name)
.map(|c| c.role)
.unwrap_or(CarrierRole::LoopState)
} else {
CarrierRole::LoopState
};
```
**ConditionOnly Inclusion** (lines 148-166):
```rust
Some((CarrierRole::ConditionOnly, _)) => {
// Phase 228-8: Include ConditionOnly carrier in exit_bindings
// (needed for latch incoming, not for exit PHI)
let binding = LoopExitBinding {
carrier_name: carrier_name.clone(),
join_exit_value: *join_exit_value,
host_slot: ValueId(0), // Placeholder - not used for ConditionOnly
role: CarrierRole::ConditionOnly,
};
bindings.push(binding);
}
```
**✅ Verdict**: ExitMetaCollector correctly includes ALL carriers (ConditionOnly + LoopState) in exit_bindings. This is correct behavior for latch incoming values.
#### 2. ExitLineReconnector Analysis
**File**: `src/mir/builder/control_flow/joinir/merge/exit_line/reconnector.rs`
**Key Behavior** (lines 121-132):
```rust
for binding in &boundary.exit_bindings {
// Phase 228-8: Skip ConditionOnly carriers (no variable_map update needed)
use crate::mir::join_ir::lowering::carrier_info::CarrierRole;
if binding.role == CarrierRole::ConditionOnly {
if verbose {
eprintln!(
"[joinir/exit-line] skip ConditionOnly carrier '{}' (no variable_map update)",
binding.carrier_name
);
}
continue; // ← CRITICAL: Skip ConditionOnly carriers
}
// ... process LoopState carriers ...
}
```
**Variable Map Update** (lines 145-154):
```rust
// Only reached for LoopState carriers (ConditionOnly skipped above)
if let Some(&phi_value) = phi_dst {
if let Some(var_vid) = builder.variable_map.get_mut(&binding.carrier_name) {
if verbose {
eprintln!(
"[joinir/exit-line] variable_map['{}'] {:?}{:?}",
binding.carrier_name, *var_vid, phi_value
);
}
*var_vid = phi_value; // ← Only LoopState carriers reach this line
}
}
```
**Contract Verification** (lines 213-262):
```rust
#[cfg(debug_assertions)]
fn verify_exit_line_contract(
boundary: &JoinInlineBoundary,
carrier_phis: &BTreeMap<String, ValueId>,
variable_map: &BTreeMap<String, ValueId>,
) {
for binding in &boundary.exit_bindings {
// Phase 228-8: Skip ConditionOnly carriers (not in variable_map by design)
if binding.role == CarrierRole::ConditionOnly {
eprintln!(
"[JoinIR/ExitLine/Contract] Phase 228-8: Skipping ConditionOnly carrier '{}' (not in variable_map)",
binding.carrier_name
);
continue; // ← Contract verification also skips ConditionOnly
}
// ... verify LoopState carriers only ...
}
}
```
**✅ Verdict**: ExitLineReconnector correctly skips ConditionOnly carriers for variable_map updates. Only LoopState carriers are reconnected.
#### 3. CarrierRole Filtering Summary
| Component | ConditionOnly Carriers | LoopState Carriers |
|-----------|------------------------|-------------------|
| **ExitMetaCollector** | ✅ Included in exit_bindings (for latch) | ✅ Included in exit_bindings |
| **ExitLineReconnector** | ✅ Skipped (no variable_map update) | ✅ Updated (variable_map reconnection) |
| **Contract Verification** | ✅ Skipped (not in variable_map) | ✅ Verified (PHI dst match) |
#### 4. Contract Compliance Verification
**Expected Contract** (from design doc):
1.**CarrierRole Discrimination**: LoopState carriers in exit PHI, ConditionOnly excluded
2.**ExitMetaCollector Inclusion**: All carriers included for latch incoming
3.**ExitLineReconnector Filtering**: Only LoopState carriers update variable_map
4.**BindingId Independence**: No BindingId-specific filtering (role-based only)
**Actual Implementation**:
1. ✅ ExitMetaCollector includes ALL carriers (lines 148-215)
2. ✅ ExitLineReconnector skips ConditionOnly (lines 124-132)
3. ✅ Contract verification enforces rules (lines 222-261)
4. ✅ CarrierRole lookup uses carrier_info (lines 109-117)
**✅ Verdict**: Full compliance with Phase 227-228 design contract.
#### 5. Code Quality Observations
**Strengths**:
- Clear separation of concerns (MetaCollector vs Reconnector)
- Explicit CarrierRole filtering (no implicit assumptions)
- Debug logging at key decision points
- Contract verification in debug builds
**Minor Issues** (non-blocking):
- ExitMetaCollector has 3-way match on `(role, init)` (lines 147-215) - slightly complex
- Reconnector has nested if-else for PHI lookup (lines 145-179) - could be flattened
**Recommendations for Future**:
- Consider extracting `should_update_variable_map(role)` helper
- Consider extracting `should_include_in_exit_bindings(role, init)` helper
#### 6. Edge Cases Verified
| Edge Case | Handling | Verdict |
|-----------|----------|---------|
| ConditionOnly carrier not in variable_map | ExitMetaCollector includes (host_slot=0) | ✅ Correct |
| LoopState carrier not in variable_map | Panic (strict) or warn (non-strict) | ✅ Correct |
| ConditionOnly carrier in exit_bindings | ExitLineReconnector skips | ✅ Correct |
| Missing PHI for ConditionOnly carrier | Allowed (expected) | ✅ Correct |
| Missing PHI for LoopState carrier | Error (strict) or warn | ✅ Correct |
#### 7. Promoted Carrier Handling
**DigitPos Example**: `digit_pos``is_digit_pos` (ConditionOnly)
1. ExitMetaCollector includes `is_digit_pos` in exit_bindings (for latch)
2. ExitLineReconnector skips `is_digit_pos` (no variable_map update)
3. Exit PHI does NOT include `is_digit_pos` (correct!)
**Trim Example**: `ch``is_ch_match` (ConditionOnly)
1. ExitMetaCollector includes `is_ch_match` in exit_bindings (for latch)
2. ExitLineReconnector skips `is_ch_match` (no variable_map update)
3. Exit PHI does NOT include `is_ch_match` (correct!)
**✅ Verdict**: Promoted carriers handled correctly per contract.
### Conclusion
**Contract Status**: ✅ **VERIFIED CORRECT**
All ExitLine components implement the CarrierRole contract as designed in Phase 227-228:
- ExitMetaCollector: Includes all carriers for latch (correct)
- ExitLineReconnector: Filters ConditionOnly carriers (correct)
- Contract verification: Enforces rules in debug builds (correct)
**No fixes required**. The implementation is correct and ready for E2E testing.
### Evidence Links
- **ExitMetaCollector**: `src/mir/builder/control_flow/joinir/merge/exit_line/meta_collector.rs` (lines 96-217)
- **ExitLineReconnector**: `src/mir/builder/control_flow/joinir/merge/exit_line/reconnector.rs` (lines 121-196)
- **CarrierRole Definition**: `src/mir/join_ir/lowering/carrier_info.rs` (lines 30-64)
- **Phase 227 Design**: Phase 227 introduced CarrierRole enum
- **Phase 228 Design**: Phase 228 added ConditionOnly filtering in ExitLine
---
## Task 81-B: E2E Test Results
**Test Date**: 2025-12-13
**Status**: ✅ **BOTH TESTS PASS**
### Test Summary
Two E2E tests added to `tests/normalized_joinir_min.rs`:
1. **test_phase81_digitpos_exitline_contract()** (DigitPos pattern)
- Uses `build_jsonparser_atoi_structured_for_normalized_dev()` fixture
- Verifies DigitPos pattern compilation succeeds
- Verifies promoted `is_digit_pos` carrier (ConditionOnly) handling
- Executes successfully: "123" → 123 ✅
2. **test_phase81_trim_exitline_contract()** (Trim pattern)
- Uses `build_jsonparser_skip_ws_structured_for_normalized_dev()` fixture
- Verifies Trim pattern compilation succeeds
- Verifies promoted `is_ch_match` carrier (ConditionOnly) handling
- Executes successfully: skip_ws(5) → 5 ✅
### Test Execution
```bash
$ cargo test --features normalized_dev --test normalized_joinir_min test_phase81
running 2 tests
test test_phase81_digitpos_exitline_contract ... ok
test test_phase81_trim_exitline_contract ... ok
test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 56 filtered out
```
### Manual Verification Commands
For detailed ExitLine logging:
```bash
# DigitPos pattern verification
HAKO_JOINIR_DEBUG=1 cargo test --features normalized_dev \
test_phase81_digitpos_exitline_contract -- --nocapture 2>&1 | grep exit-line
# Expected: [joinir/exit-line] skip ConditionOnly carrier 'is_digit_pos'
# Legacy: NYASH_JOINIR_DEBUG=1 also works (deprecated)
# Trim pattern verification
HAKO_JOINIR_DEBUG=1 cargo test --features normalized_dev \
test_phase81_trim_exitline_contract -- --nocapture 2>&1 | grep exit-line
# Expected: [joinir/exit-line] skip ConditionOnly carrier 'is_ch_match'
# Legacy: NYASH_JOINIR_DEBUG=1 also works (deprecated)
```
### Test Files Modified
- **tests/normalized_joinir_min.rs**: Added 2 new tests (lines 2227-2323)
- Phase 81-B section clearly marked
- Dev-only tests (gated by `#[cfg(all(feature = "normalized_dev", debug_assertions))]`)
- Zero production impact
### Verification Results
| Aspect | DigitPos Test | Trim Test |
|--------|---------------|-----------|
| Compilation | ✅ Pass | ✅ Pass |
| Module Structure | ✅ 3 functions | ✅ ≥3 functions |
| Entry Function | ✅ Exists | ✅ Exists |
| Execution | ✅ 123 (correct) | ✅ 5 (correct) |
| ExitLine Contract | ✅ Verified | ✅ Verified |
### Contract Compliance
Both tests confirm the ExitLine contract:
- **ConditionOnly carriers** (`is_digit_pos`, `is_ch_match`): Included in exit_bindings for latch, excluded from Exit PHI
- **LoopState carriers** (result, i, etc.): Included in both exit_bindings and Exit PHI
- **Compilation succeeds**: No ExitLine reconnection errors
- **Execution succeeds**: Correct output values
---
## Task 81-D: Smoke Test Results
**Test Date**: 2025-12-13
**Status**: ✅ **NO NEW REGRESSIONS**
### Smoke Test Execution
```bash
$ tools/smokes/v2/run.sh --profile quick
Test Results Summary
Profile: quick
Total: 2
Passed: 1
Failed: 1
Duration: .062845590s
```
### Classification
**Failed Test**: `json_lint_vm`
- **Classification**: Pre-existing failure (out of scope)
- **Root Cause**:
1. Plugin loading error: `libnyash_map_plugin.so` missing
2. JoinIR pattern error: `StringUtils.index_of/2` not supported
- **Phase 81 Impact**: None (failure existed before Phase 81)
- **Verdict**: NOT a regression
**Passed Test**: Other quick smoke tests
- **Verdict**: Baseline maintained
### Baseline Comparison
| Metric | Before Phase 81 | After Phase 81 | Change |
|--------|----------------|----------------|--------|
| Lib Tests | 970/970 PASS | 970/970 PASS | ✅ No change |
| Integration Tests | 56 tests | 58 tests (+2 Phase 81) | ✅ +2 E2E tests |
| Smoke Tests (quick) | 1/2 PASS | 1/2 PASS | ✅ No change |
### Regression Assessment
**No new regressions introduced by Phase 81**:
- All 970 lib tests pass (baseline maintained)
- 2 new integration tests pass (Phase 81 E2E)
- Smoke test baseline unchanged (1/2 PASS, same as before)
- Pre-existing failure is unrelated to ExitLine contract
---
## Phase 82/83 Addendum: Debug Flag SSOT & Fallback Verification
### Debug Flag Unification (Phase 82)
**Changes**:
- Centralized JoinIR debug flag reading to `is_joinir_debug()` function
- Replaced 16 direct `std::env::var("NYASH_JOINIR_DEBUG")` calls
- Updated documentation to recommend `HAKO_JOINIR_DEBUG=1`
**Backward Compatibility**:
- Both `HAKO_JOINIR_DEBUG` and `NYASH_JOINIR_DEBUG` work
- Recommended: Use `HAKO_JOINIR_DEBUG=1` (NYASH_ variant deprecated)
### Fallback Behavior (Phase 83)
**Expected**: Promoted carriers (DigitPos/Trim) should NEVER fallback to name-based lookup
**Verification**:
```bash
# DigitPos pattern - promoted carrier 'is_digit_pos'
HAKO_JOINIR_DEBUG=1 cargo test --features normalized_dev \
test_phase81_digitpos_exitline_contract -- --nocapture 2>&1 | grep "\[binding_pilot"
# Trim pattern - promoted carrier 'is_ch_match'
HAKO_JOINIR_DEBUG=1 cargo test --features normalized_dev \
test_phase81_trim_exitline_contract -- --nocapture 2>&1 | grep "\[binding_pilot"
```
**Expected Output**:
- `[binding_pilot/hit]` tags ✅ (BindingId path success)
- NO `[binding_pilot/fallback]` tags ❌ (name fallback should NOT occur)
**Status (Phase 83)**:
- All Phase 81 tests PASS
- No fallback to name-based lookup detected
- Promoted carriers correctly resolved via BindingId path
---