refactor(joinir): Phase 286C-2.1 - 3-stage pipeline scaffolding (Scan/Plan/Apply)
- Create 3-stage pipeline architecture to solve borrow checker conflicts
- Stage 1 (ScanBox): Read-only scanning, identify rewrites (170 lines)
- Stage 2 (PlanBox): Pure transformation, generate new blocks (85 lines)
- Stage 3 (ApplyBox): Builder mutation only (75 lines)
New Files:
- scan_box.rs: Stage 1 - Read-only scan for RewritePlan
- plan_box.rs: Stage 2 - Transform RewritePlan → RewrittenBlocks
- apply_box.rs: Stage 3 - Apply RewrittenBlocks to MirBuilder
- C-2.1-pipeline-refactoring.md: Implementation guide
Data Structures:
- RewritePlan: Describes WHAT to rewrite (tail calls, returns, PHI, params)
- RewrittenBlocks: Contains HOW to rewrite (new blocks, replacements, inputs)
Benefits:
- Borrow checker safety: No overlapping mutable/immutable borrows
- Single responsibility: Each stage has one clear purpose
- Testability: Each stage can be unit tested independently
- Maintainability: Clear data flow, isolated changes
Status:
- Scaffolding: ✅ Complete (structure defined, stub implementations)
- Integration: ⏳ Next step (refactor merge_and_rewrite to use 3 stages)
Build: cargo build --release ✅
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
tomoaki
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