feat(joinir): Phase 171-C-2 Trim pattern detection in LoopBodyCarrierPromoter

Implements the Trim pattern detection logic for carrier promotion:

- find_definition_in_body(): Iterative AST traversal to locate variable definitions
- is_substring_method_call(): Detects substring() method calls
- extract_equality_literals(): Extracts string literals from OR chains (ch == " " || ch == "\t")
- TrimPatternInfo: Captures detected pattern details for carrier promotion

This enables Pattern 5 to detect trim-style loops:
```hako
loop(start < end) {
    local ch = s.substring(start, start+1)
    if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" {
        start = start + 1
    } else {
        break
    }
}
```

Unit tests cover:
- Simple and nested definition detection
- substring method call detection
- Single and chained equality literal extraction
- Full Trim pattern detection with 2-4 whitespace characters

Next: Phase 171-C-3 integration with Pattern 2/4 routing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/development/current/main/phase170-completion-report.md

@@ -1,8 +1,8 @@
 # Phase 170: JsonParserBox JoinIR Preparation & Re-validation - Completion Report
 
 **Date**: 2025-12-07
-**Duration**: 1 session (autonomous work)
-**Status**: ✅ **Complete** - Environment prepared, blockers identified, next phase planned
+**Duration**: 2 sessions (autonomous work + bug fix verification)
+**Status**: ✅ **Complete** - Environment prepared, bug fix verified, next phase planned
 
 ---
 
@@ -374,5 +374,77 @@ match update.kind {
 - 代表的な ループスモーク 16 本のうち 15 本が PASS（1 本は既知の別問題）で、  
   既存パターンへの回帰は維持されている。
 
-この状態を起点に、今後 Phase 170‑C‑3 以降で `LoopUpdateSummary` の中身（AST/MIR ベースの解析）だけを差し替えることで、  
+この状態を起点に、今後 Phase 170‑C‑3 以降で `LoopUpdateSummary` の中身（AST/MIR ベースの解析）だけを差し替えることで、
 段階的に carrier 名ヒューリスティックを薄めていく計画。
+
+---
+
+## Phase 170-D: Loop Condition Scope Analysis - Bug Fix Verification ✅
+
+**Date**: 2025-12-07 (Session 2)
+**Status**: ✅ **Bug Fix Complete and Verified**
+
+### Bug Fix: Function Parameter Misclassification
+
+**Issue**: Function parameters (`s`, `pos` in JsonParser methods) were incorrectly classified as **LoopBodyLocal** when used in loop conditions.
+
+**Root Cause**: `is_outer_scope_variable()` in `condition_var_analyzer.rs` defaulted unknown variables (not in `variable_definitions`) to LoopBodyLocal.
+
+**Fix** (User Implemented):
+```rust
+// File: src/mir/loop_pattern_detection/condition_var_analyzer.rs (lines 175-184)
+
+// At this point:
+// - Variable is NOT in body_locals
+// - No explicit definition info
+// This typically means "function parameter" or "outer local"
+true  // ✅ Default to OuterLocal for function parameters
+```
+
+### Verification Results
+
+**Test 1: Function Parameter Loop** ✅
+- **File**: `/tmp/test_jsonparser_simple.hako`
+- **Result**: `Phase 170-D: Condition variables verified: {"pos", "s", "len"}`
+- **Analysis**: Function parameters correctly classified as OuterLocal
+- **New blocker**: Method calls (Pattern 5+ feature, not a bug)
+
+**Test 2: LoopBodyLocal Correct Rejection** ✅
+- **File**: `local_tests/test_trim_main_pattern.hako`
+- **Result**: `Phase 170-D: Condition variables verified: {"ch", "end", "start"}`
+- **Error**: "Variable 'ch' not bound in ConditionEnv" (correct rejection)
+- **Analysis**: `ch` is defined inside loop, correctly rejected by Pattern 2
+
+**Test 3: JsonParser Full File** ✅
+- **File**: `tools/hako_shared/json_parser.hako`
+- **Result**: Error about MethodCall, not variable classification
+- **Analysis**: Variable scope classification now correct, remaining errors are legitimate feature gaps
+
+### Impact
+
+**What the Fix Achieves**:
+- ✅ Function parameters work correctly: `s`, `pos` in JsonParser
+- ✅ Carrier variables work correctly: `start`, `end` in trim loops
+- ✅ Outer locals work correctly: `len`, `maxLen` from outer scope
+- ✅ Correct rejection: LoopBodyLocal `ch` properly rejected (not a bug)
+
+**Remaining Blockers** (Pattern 5+ features, not bugs):
+- ⚠️ Method calls in conditions: `loop(pos < s.length())`
+- ⚠️ Method calls in loop body: `s.substring(pos, pos+1)`
+- ⚠️ LoopBodyLocal in break conditions: `if ch == " " { break }`
+
+### Documentation
+
+**Created**:
+1. ✅ `phase170-d-fix-verification.md` - Comprehensive verification report
+2. ✅ `phase170-d-fix-summary.md` - Executive summary
+3. ✅ Updated `CURRENT_TASK.md` - Bug fix section added
+4. ✅ Updated `phase170-d-impl-design.md` - Bug fix notes
+
+### Next Steps
+
+**Priority 1**: Pattern 5+ implementation for LoopBodyLocal in break conditions
+**Priority 2**: .hako rewrite strategy for complex method calls
+**Priority 3**: Coverage metrics for JsonParser loop support
+
+**Build Status**: ✅ `cargo build --release` successful (0 errors, 50 warnings)