scorer

Scorer

Vendor-agnostic interface for computing success probability scores for code changes.

Interface

Scorer

Computes a success probability for a given change.

type Scorer interface {
    Score(ctx context.Context, change entity.Change) (float64, error)
}

• change: A entity.Change identifying the code change to score.
• Score: Returns a probability between 0.0 and 1.0 indicating the likelihood of a successful land. Returns an error if scoring fails.

Implementations

Heuristic

Scores a change by extracting a numeric value via a ValueFunc and matching it against ordered buckets. Each bucket maps a [Min, Max] range to a probability.

s := heuristic.New(
    []heuristic.Bucket{
        {Min: 0, Max: 5, Score: 0.95},
        {Min: 6, Max: 20, Score: 0.75},
        {Min: 21, Max: 100, Score: 0.5},
    },
    func(ctx context.Context, change entity.Change) (int, error) {
        // resolve the change into a numeric metric
        return filesChanged, nil
    },
)

score, err := s.Score(ctx, change)

Composite

Combines multiple named scorers into a single score using a reduce function. The reduce function receives a map[string]float64 mapping scorer names to their scores, enabling domain-aware aggregation.

Built-in reduce functions: Min, Max, Avg.

s := composite.New(
    map[string]scorer.Scorer{
        "files": fileScorer,
        "deps":  depScorer,
    },
    composite.Min,
)

score, err := s.Score(ctx, change)

Implementing a Backend

1. Create extension/scorer/{backend}/ directory
2. Implement the Scorer interface
3. Accept entity.Change and resolve it into whatever data the implementation needs