feat(parser): Phase 285A1.4 & A1.5 - Weak field sugar + Parser hang fix

A1.4: Add sugar syntax `public weak parent` ≡ `public { weak parent }`
A1.5: Fix parser hang on unsupported `param: Type` syntax

Key changes:
- A1.4: Extend visibility parser to handle weak modifier (fields.rs)
- A1.5: Shared helper `parse_param_name_list()` with progress-zero detection
- A1.5: Fix 6 vulnerable parameter parsing loops (methods, constructors, functions)
- Tests: Sugar syntax (OK/NG), parser hang (timeout-based)
- Docs: lifecycle.md, EBNF.md, phase-285a1-boxification.md

Additional changes:
- weak() builtin implementation (handlers/weak.rs)
- Leak tracking improvements (leak_tracker.rs)
- Documentation updates (lifecycle, types, memory-finalization, etc.)

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

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

docs/development/current/main/investigations/loopbuilder-removal-quick-summary.md

@@ -0,0 +1,147 @@
+# LoopBuilder Removal - Quick Summary
+
+**Date**: 2025-12-24
+**Test Failure**: `core_direct_array_oob_set_rc_vm`
+**Error**: `[joinir/freeze] Loop lowering failed: JoinIR does not support this pattern, and LoopBuilder has been removed`
+
+---
+
+## TL;DR
+
+✅ **User hypothesis is CORRECT**: Old `.hako` code not compatible with new JoinIR patterns
+
+❌ **NOT a bug**: Expected feature gap (20% of patterns not yet covered)
+
+⭐ **Fix**: Rewrite BundleResolver loops to use supported Pattern 1 or Pattern 2
+
+---
+
+## What Happened?
+
+### Timeline
+
+1. **Dec 4, 2025 (Phase 186-187)**: LoopBuilder deleted (1,758 lines removed)
+2. **Dec 5-6, 2025 (Phase 188)**: JoinIR Patterns 1-3 implemented (80% coverage)
+3. **Dec 24, 2025 (Today)**: BundleResolver test fails (falls in 20% gap)
+
+### Why This Fails
+
+**BundleResolver.resolve/4** uses a complex loop pattern:
+- Multiple carriers (5+ variables: i, j, seg, pos, k)
+- Nested loops
+- Non-unit increment (`i = j + 3`)
+- Conditional assignments
+
+**Current JoinIR patterns** don't cover this:
+- ✅ Pattern 1: Simple While (single carrier, no breaks)
+- ✅ Pattern 2: Conditional Break (simple breaks only)
+- ✅ Pattern 3: If-Else PHI (arithmetic accumulation only)
+- ❌ **Pattern 6** (Complex Multi-Carrier): **Not implemented yet**
+
+---
+
+## What is LoopBuilder?
+
+**Before Phase 187**:
+- Legacy loop lowering system (8 files, 1,000+ lines)
+- Handled all loop patterns (but with bugs)
+- Silent fallback when JoinIR didn't match
+
+**After Phase 187**:
+- ❌ Completely deleted
+- ✅ Replaced by JoinIR Frontend (pattern-based)
+- ✅ Explicit failures (no silent fallbacks)
+
+**Why removed?**
+> "Explicit failures replace implicit fallbacks. Future JoinIR expansion is the only way forward."
+
+---
+
+## How to Fix
+
+### Option A: Rewrite BundleResolver Loops ⭐ **RECOMMENDED**
+
+**Before** (unsupported):
+```nyash
+local i = 0
+loop(i < table.length()) {
+    local j = table.indexOf("|||", i)
+    // ... complex processing
+    if j < 0 { break }
+    i = j + 3  // Non-unit increment
+}
+```
+
+**After** (Pattern 2 compatible):
+```nyash
+local i = 0
+local done = 0
+loop(i < table.length() and done == 0) {
+    local j = table.indexOf("|||", i)
+    // ... complex processing
+    if j < 0 {
+        done = 1
+    } else {
+        i = j + 3
+    }
+}
+```
+
+**Tips**:
+- Convert non-unit increments to unit increments if possible
+- Convert breaks to condition checks
+- Reduce carrier count (merge variables if possible)
+
+### Option B: Implement Pattern 6 ⏳ **FUTURE WORK**
+
+**Effort**: Large (Pattern 1-3 took 1,802 lines + design)
+**Timeline**: Phase 189+
+**Benefit**: Supports all complex loops
+
+---
+
+## Quick Reference
+
+### Supported Patterns (Phase 188)
+
+| Pattern | Example | Status |
+|---------|---------|--------|
+| **Pattern 1** | `loop(i < n) { i++ }` | ✅ Works |
+| **Pattern 2** | `loop(true) { if(...) break }` | ✅ Works |
+| **Pattern 3** | `loop(...) { if(...) sum += x else sum += 0 }` | ✅ Works |
+| **Complex Multi-Carrier** | BundleResolver loops | ❌ Not yet |
+
+### Where to Find More
+
+- **Full Analysis**: `loopbuilder-removal-compatibility-analysis.md` (this directory)
+- **Phase 188 Docs**: `docs/private/roadmap2/phases/phase-188-joinir-loop-pattern-expansion/`
+- **BundleResolver Source**: `lang/src/compiler/entry/bundle_resolver.hako`
+
+### Git History
+
+```bash
+# Find LoopBuilder removal
+git log --all --oneline --grep="Phase 187"
+# fa8a96a51 docs(joinir): Phase 187 LoopBuilder Physical Removal
+
+# See deleted files
+git show fa8a96a51 --stat
+# 13 files changed, 56 insertions(+), 1758 deletions(-)
+```
+
+---
+
+## Key Takeaways
+
+1. ✅ **This is NOT a bug**—it's an expected gap (20% of patterns)
+2. ✅ **LoopBuilder is gone forever**—no plans to restore
+3. ✅ **Fix: Rewrite loops**—use Pattern 1 or Pattern 2
+4. ✅ **Future: Implement Pattern 6**—if this becomes a blocker
+
+**Philosophy**:
+> Explicit failures drive architecture forward. No silent fallbacks!
+
+---
+
+**Last Updated**: 2025-12-24
+**Status**: Investigation complete, recommendations provided