# Reliability Review Report

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

## 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 -- all aspects of the implementation meet reliability standards)

## Analysis Notes

The `QueryEngine` implementation was evaluated against all five reliability categories from the Power of Ten rules:

**1. Bounded Iteration**: No loops exist in `QueryEngine::search()`. The method is a straight-line validation pipeline (empty check, size bound, config validation, delegate). The only iteration in the changeset is a bounded `for _ in 0..10` loop in `test_deterministic_results`, which has an explicit upper bound. No unbounded retries, pagination loops, or recursive calls.

**2. Assertion Density**: Preconditions are validated explicitly at the trust boundary before any I/O:
- Empty query short-circuit (`query.text.is_empty()`)
- Byte-length upper bound (`query.text.len() > MAX_QUERY_BYTES`)
- BM25F config validation (`cfg.validate()`)

The `MAX_QUERY_BYTES = 4096` constant provides a well-documented, generous-but-finite bound. The byte-length check is consistent with the constant's name (Rust `String::len()` returns byte count). Validation order is correct: cheapest checks first, fail-fast before index I/O.

**3. Allocation Discipline**: `Vec::new()` on the empty-query path is zero-allocation. `format!()` allocations only occur on error paths, not in the hot path. No per-query heap allocation in the success path beyond what the inner layer performs.

**4. Indirection Limits**: Single-level `Box<dyn SearchLayer>` indirection. No nested boxing, no pointer-to-pointer patterns. The `SearchLayer` trait is `Send + Sync`, and `QueryEngine` auto-derives both bounds from its sole `Box<dyn SearchLayer>` field.

**5. Metaprogramming Restraint**: No macros, no recursive generics, no reflection. The implementation is straightforward imperative code.

## Summary

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

**Reliability Score**: 9/10
**Recommendation**: APPROVED

The implementation follows all five Power of Ten reliability principles. Every input has an explicit bound, validation order is cheapest-first, error paths use Result types (no panics), and indirection is minimal. The only reason this is not 10/10 is that the decorator does not assert its own invariant (e.g., that `inner` is non-null after construction), but in Rust this is guaranteed by the type system (`Box<dyn SearchLayer>` cannot be null), so no code-level assertion is needed.
