# Sprint 47 Plan: Rust Semantic Lowering to Core IR

## Context

Sprint 47 makes Rust the first full-fidelity source language for the new semantic
core. This sprint focuses on lowering correctness: ownership/borrowing, traits,
error semantics, async semantics, and macro boundary behavior.

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## Goals

1. Lower real Rust constructs into `SemanticCoreIR`
2. Build ownership and borrow-region graph extraction
3. Capture trait and generics semantics in IR
4. Emit review packets for unsupported/unsafe regions

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## Steps

### Step 699: Rust ownership/borrow graph extractor (12 tests)
### Step 700: Lifetime region lowering (10 tests)
### Step 701: Trait + impl lowering (10 tests)
### Step 702: Generic/monomorphization intent model (10 tests)
### Step 703: Error model lowering (`Result`, `Option`, panic) (10 tests)
### Step 704: Async/await state intent lowering (10 tests)
### Step 705: Macro boundary capture + fallback policy (8 tests)
### Step 706: Unsafe block risk packet generator (8 tests)
### Step 707: `whetstone_analyze_rust_semantics` MCP tool (8 tests)
### Step 708: Sprint 47 integration summary + regression (8 tests)

For each step above:
- Create/extend modules under `editor/src/rust_ir/`
- Add deterministic JSON packets for downstream C++ raising
- Attach confidence + review-required tags at lowering time

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## Verification Focus

- Rust sample corpus must cover: ownership transfer, borrowing, lifetimes,
  traits, generics, async, unsafe, macro usage
- Unsupported features must fail closed with actionable diagnostics
- No silent semantic drop allowed