# S02 Post-Slice Assessment

**Verdict:** Roadmap unchanged. S03 and S04 proceed as planned.

## Risk Retirement

S02 retired the "file watcher + single-threaded architecture" risk. The drain-at-dispatch pattern with separate RefCells (D091) works — two-phase borrowing avoids conflicts, proven by modify-then-query and remove-then-query integration tests with zero RefCell panics.

## Success Criterion Coverage

All 6 milestone success criteria have remaining owners:

- `aft_call_tree` cross-file → S01 ✓ (done)
- `aft_callers` modify-then-query → S02 ✓ (done)
- `aft_trace_to` entry point paths → S03
- `aft_impact` 5+ callers → S04
- `aft_trace_data` value tracking → S04
- Worktree boundaries → S01 infrastructure, inherited by S03/S04

## Boundary Map Accuracy

S02→S03 boundary holds. S03 consumes:
- `callers_of(file, symbol, depth)` for backward traversal — available and proven
- Forward graph from S01 — available
- `invalidate_file()` ensures fresh data — available

No boundary contracts need updating.

## Requirement Coverage

- R023 (trace_to) → S03 — active, mapped
- R024 (trace_data) → S04 — active, mapped
- R025 (impact) → S04 — active, mapped
- R026 (entry point detection) → S03 — active, mapped

No requirements invalidated, deferred, or newly surfaced by S02.

## New Risks

None. S02 completed without deviations.
