# Scanner Rust Analyzer Benchmarks (Sprint 130)

## Summary

- New fixtures under `src/Scanner/__Tests/StellaOps.Scanner.Analyzers.Lang.Tests/Fixtures/lang/rust/` capture heuristic and fallback behaviours.
- `RustLanguageAnalyzerBenchmark` (see `src/Scanner/__Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks`) exercises the new fixtures and emits heuristic coverage metrics.
- March 2025 snapshot: heuristic detection covers 3 crates (`reqwest`, `serde`, `tokio`) vs competitor baseline (1 crate), yielding 300% relative coverage.

## Running the benchmarks

```bash
# Build once in Release for accurate metrics
DOTNET_CLI_UI_LANGUAGE=en dotnet build src/Scanner/__Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks.csproj -c Release

# Dump heuristic output
DOTNET_CLI_UI_LANGUAGE=en dotnet run --no-build   --project src/Scanner/__Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks.csproj   -- --dump-heuristics

# Dump fallback binary output (bin provenance)
DOTNET_CLI_UI_LANGUAGE=en dotnet run --no-build   --project src/Scanner/__Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks.csproj   -- --dump-fallback

# Run benchmarks (optional)
DOTNET_CLI_UI_LANGUAGE=en dotnet run   --project src/Scanner/__Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks/StellaOps.Scanner.Analyzers.Lang.Rust.Benchmarks.csproj   -c Release
```

> BenchmarkDotNet emits warnings when running against Debug builds. Use `-c Release` or set `config.WithOptions(ConfigOptions.DisableOptimizationsValidator)` if you need debugging traces.

## Heuristic coverage comparison

| Fixture | Our detector | Competitor baseline | Relative gain |
|---------|--------------|---------------------|---------------|
| `lang/rust/heuristics` | `reqwest`, `serde`, `tokio` | `serde` | **+300%** (3/1)

Competitor baseline data lives in `competitor-baseline.json` alongside the heuristics fixture and is used by `RustHeuristicCoverageComparisonTests`.

## Fallback binary snapshot

```
componentKey: bin::sha256:10f3c03766e4403be40add0467a2b2d07fd7006e4b8515ab88740ffa327ea775
metadata:
  binary.path    -> usr/local/bin/opaque_bin
  binary.sha256  -> 10f3c03766e4403be40add0467a2b2d07fd7006e4b8515ab88740ffa327ea775
  provenance     -> binary
evidence:
  source=binary locator=usr/local/bin/opaque_bin sha256=10f3c03766e4403be40add0467a2b2d07fd7006e4b8515ab88740ffa327ea775
```

This snapshot is persisted in `expected.json` for repeatable regression tests.