# Complexity Review Report

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

## Issues in Your Changes (BLOCKING)

No blocking complexity issues found.

## Issues in Code You Touched (Should Fix)

No should-fix complexity issues found.

## Pre-existing Issues (Not Blocking)

No pre-existing complexity issues found.

## Suggestions (Lower Confidence)

No suggestions.

## Summary

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

**Complexity Score**: 10
**Recommendation**: APPROVED

## Rationale

The `QueryEngine` implementation is exemplary in its simplicity and clarity:

**Production code (`query.rs` -- 76 lines):**
- The `search()` method has a cyclomatic complexity of 4 (three guard clauses plus the delegation call), well within the "good" threshold of < 5.
- Maximum nesting depth is 2 (inside `if let Some(ref cfg)` block), well within bounds.
- The struct has a single field (`inner`), and the constructor is a one-liner.
- The `name()` method is a trivial string literal return.
- No magic values -- `MAX_QUERY_BYTES` is a named constant with documentation explaining the 4 KiB choice.
- Linear control flow with early returns -- each validation step short-circuits independently. No complex boolean expressions.
- Function length: `search()` is 17 lines, `new()` is 3 lines, `name()` is 3 lines. All well under the 30-line "good" threshold.
- The file totals 76 lines including module docs and test module reference. Well under the 300-line "good" threshold.
- Zero parameters beyond `&self` and the single `&SearchQuery` reference -- clean API surface.

**Test code (`query_tests.rs` -- 282 lines):**
- Tests are organized in three clear phases (Validation, Integration, Edge cases) with section headers.
- The `build_query_engine` helper eliminates boilerplate across 16 tests.
- Each test follows a single-assertion, single-behavior pattern with descriptive names.
- The `test_search_delegates_to_inner_layer` test at 35 lines is the longest, but its length is driven by building two independent indexes for comparison -- a reasonable structural requirement, not unnecessary complexity.
- The `test_pagination_passes_through` test uses an early return guard (`if all_results.len() < 2`) rather than deep nesting -- good pattern.

This is a textbook decorator implementation: minimal surface area, single responsibility, validate-then-delegate with no hidden control flow. No complexity improvements needed.
