---

name: benchmark-advisor description: Suggests which benchmarks to run based on code changes

Benchmark Advisor Skill

This skill analyzes your code changes and recommends specific Criterion benchmarks to run.

When to Use

This skill automatically activates when:

• You've made changes to performance-critical code
• You're preparing to commit performance-related work
• You want to verify your changes don't introduce regressions

How It Works

1. Detects Changed Files: Analyzes git diff to see which files you've modified
2. Maps to Benchmarks: Uses pattern matching to identify relevant benchmarks
3. Provides Recommendations: Suggests specific cargo bench commands with explanations

Usage

Simply ask:

• "What benchmarks should I run?"
• "Which benchmarks are affected by my changes?"
• "Suggest benchmarks for my current work"

Skill Logic

Copy# 1. Detect changed files
CHANGED_FILES=$(git diff --name-only HEAD)

# 2. Load mapping configuration
# See mapping.toml for file-to-benchmark mappings

# 3. Match changed files to benchmarks
# Example mappings:
#   src/cache/**/*.rs → cargo bench --bench cache
#   src/config/**/*.rs → cargo bench --bench config
#   src/main.rs → cargo bench (full suite - affects startup time)

# 4. Generate recommendation with explanation

Example Interaction

User: "What benchmarks should I run?"

Claude: "I analyzed your changes and found modifications to:

• src/cache/manifest.rs
• src/cache/lru.rs

Recommended benchmarks:

Copycargo bench --bench cache

Why: Changes to cache implementation files can affect cache operation performance (get_model, add_model, remove_model, lru_eviction).

You can also run the full suite if you want comprehensive validation:

Copycargo bench
```"

## Mapping Configuration

The skill uses `mapping.toml` to define file patterns and their corresponding benchmarks:

```toml
# Cache-related files
[[mapping]]
pattern = "src/cache/**/*.rs"
benchmark = "cargo bench --bench cache"
reason = "Cache implementation changes can affect cache operation performance"

# Config-related files
[[mapping]]
pattern = "src/config/**/*.rs"
benchmark = "cargo bench --bench config"
reason = "Config loading and merging performance may be impacted"

# Main entry point
[[mapping]]
pattern = "src/main.rs"
benchmark = "cargo bench"
reason = "Main entry point affects startup time - run full suite"

Output Format

Concise: Lists changed files, recommended command, and brief explanation

No false positives: Only suggests benchmarks for performance-critical changes

Actionable: Provides exact commands to copy/paste