# Performance Review Report

**Branch**: feat/rskim-search-foundation -> main
**Date**: 2026-05-11

## 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)

- **SearchResult uses Vec<Range<usize>> for match_positions** - `crates/rskim-search/src/types.rs:167` (Confidence: 65%) — When a search returns many results (hundreds), each `SearchResult` allocates a separate heap Vec for `match_positions`. A `SmallVec<[Range<usize>; 4]>` would avoid heap allocation for the common case (1-4 match positions per result). This is a micro-optimization that only matters at scale and can be deferred to Wave 1+ when actual search is implemented.

- **SearchQuery::new allocates via Into<String>** - `crates/rskim-search/src/types.rs:138` (Confidence: 62%) — `SearchQuery::new(text: impl Into<String>)` always allocates for the query text. In hot-loop scenarios (batch queries), accepting `&str` with a lifetime or a `Cow<'_, str>` could avoid allocation. However, since queries are user-initiated (one at a time), this is unlikely to matter in practice.

## Summary

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

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

## Analysis Notes

This PR introduces a pure foundation crate (`rskim-search`) containing only type definitions, trait contracts, and a CLI stub. The performance implications are minimal because:

1. **No hot-path code**: The new crate defines traits and data types — no algorithmic logic, no I/O, no loops. Performance characteristics will be determined by implementations in later waves.

2. **Well-designed type choices**: `FileId(u32)` is Copy-friendly (4 bytes), `SearchField` is a Copy enum, `NodeInfo` uses `&'static str` for zero-allocation kind lookups, and `SearchField::name()` returns `&'static str` explicitly to avoid serde overhead in BM25F hot loops.

3. **Trait design supports parallelism**: `SearchLayer: Send + Sync` and `LayerBuilder: Send` ensure implementations can be shared across rayon worker threads without contention — consistent with the project's established parallel processing pattern.

4. **Edition 2024 if-let chaining**: The collapsible_if changes (`structure.rs:298-303`, `signatures.rs:155-161`, `pseudo.rs:580-588`) are semantically identical to the original nested-if pattern and compile to the same machine code. No performance delta.

5. **thiserror 1.0 -> 2.0 upgrade**: This is a proc-macro change that affects compile time only, not runtime. Error types remain zero-cost wrappers.

6. **No regression risk to existing hot paths**: The transform modules (`minimal.rs`, `pseudo.rs`, `structure.rs`, `signatures.rs`) received only syntactic changes (import reordering, if-let chaining, comment reformatting). No logic or algorithm changes.
