# Regression Review Report

**Branch**: feat/186-query-engine -> main
**Date**: 2026-05-18T14:50

## Issues in Your Changes (BLOCKING)

### CRITICAL

(none)

### HIGH

(none)

## Issues in Code You Touched (Should Fix)

(none)

## Pre-existing Issues (Not Blocking)

(none)

## Suggestions (Lower Confidence)

(none)

## Summary

| Category | CRITICAL | HIGH | MEDIUM | LOW |
|----------|----------|------|--------|-----|
| Blocking | 0 | 0 | 0 | - |
| Should Fix | - | 0 | 0 | - |
| Pre-existing | - | - | 0 | 0 |

**Regression Score**: 10/10
**Recommendation**: APPROVED

## Analysis Notes

### Lost Functionality: None detected

- No exports were removed. The `lib.rs` re-export line was extended from 5 items to 7 items (`MAX_QUERY_BYTES` and `QueryEngine` added); all 5 original exports (`BM25FConfig`, `FIELD_COUNT`, `bm25f_score`, `classify_source`, `dominant_field`) are preserved verbatim.
- No files were deleted.
- No CLI options were changed.
- `lexical/mod.rs` gained two new lines (`pub mod query` and `pub use query::{...}`) while all three original module declarations and re-exports remain unchanged.

### Broken Behavior: None detected

- No existing function signatures were modified.
- No return types were changed.
- No default values were altered.
- The `SearchLayer` trait contract is unchanged (same `search` and `name` methods with identical signatures).
- `QueryEngine` is a pure additive decorator: it wraps an inner `Box<dyn SearchLayer>` and either short-circuits with validation errors or delegates unchanged to the inner layer. The inner layer receives the exact same `&SearchQuery` reference, unmodified.

### Intent vs Reality: Aligned

- PR description states "Option B (stateless decorator with inline validation)" -- the implementation matches: `QueryEngine` holds only `inner: Box<dyn SearchLayer>` (stateless), performs inline validation in `search()`, and delegates everything else.
- The four validation rules described in the PR body are implemented in exactly the order stated: (1) empty text -> `Ok(vec![])`, (2) oversized text -> `Err(InvalidQuery)`, (3) invalid BM25F -> `Err(InvalidQuery)`, (4) delegate to inner.
- Commit messages accurately describe what each commit does: initial feature, re-export consolidation, style simplification.

### Incomplete Migrations: Not applicable

- `QueryEngine` and `MAX_QUERY_BYTES` are new symbols with zero existing consumers outside the new files. No migration is needed. They are exported at both the `lexical` module level and the crate root, providing a clean public API surface for future consumers.

### Test Suite Verification

- Full `rskim-search` test suite: 240 pass, 0 fail, 2 skip.
- All 16 new `QueryEngine` tests pass (plus 14 pre-existing `query`-matching tests).
- Full workspace compiles cleanly with `cargo check --workspace`.

### Regression Checklist

- [x] No exports removed without deprecation
- [x] Return types backward compatible
- [x] Default values unchanged
- [x] Side effects preserved
- [x] All consumers of changed code updated (no existing consumers affected)
- [x] No migration required (purely additive)
- [x] CLI options preserved
- [x] API endpoints preserved
- [x] Commit messages match implementation
- [x] No breaking changes
