Initial commit: smartrun MVP

Garmin run classification and progression tracker. Go backend (MCP
client to mcp-garmin, SQLite store, deterministic rule engine, REST
API) and React/TS frontend (Dashboard, Review Queue, Workout Kinds).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/internal/classify/engine.go

@@ -0,0 +1,63 @@
+package classify
+
+import "sort"
+
+const (
+	StatusAssigned    = "assigned"
+	StatusNeedsReview = "needs_review"
+
+	// DefaultMinConfidence is the score below which even a single matching
+	// kind is sent to manual review rather than auto-assigned.
+	DefaultMinConfidence = 0.6
+)
+
+// RuleKind is one active workout kind's rule, as loaded from the store.
+type RuleKind struct {
+	WorkoutKindID int64
+	Name          string
+	Rule          Node
+}
+
+// ScoredKind is one kind that matched an activity's metrics, with its
+// confidence score.
+type ScoredKind struct {
+	WorkoutKindID int64   `json:"workout_kind_id"`
+	Name          string  `json:"name"`
+	Score         float64 `json:"score"`
+}
+
+// Result is the outcome of classifying one activity.
+type Result struct {
+	Status        string
+	WorkoutKindID *int64
+	Confidence    *float64
+	Candidates    []ScoredKind // every kind that matched, sorted by score descending
+}
+
+// Classify evaluates every active kind's rule against ctx and decides
+// whether the activity is cleanly assignable, or needs manual review
+// because zero kinds matched, multiple kinds matched, or the single match's
+// confidence fell below minConfidence.
+func Classify(ctx MetricContext, kinds []RuleKind, minConfidence float64) Result {
+	candidates := []ScoredKind{}
+	for _, k := range kinds {
+		matched, score := k.Rule.Evaluate(ctx)
+		if matched {
+			candidates = append(candidates, ScoredKind{WorkoutKindID: k.WorkoutKindID, Name: k.Name, Score: score})
+		}
+	}
+	sort.Slice(candidates, func(i, j int) bool { return candidates[i].Score > candidates[j].Score })
+
+	if len(candidates) != 1 {
+		return Result{Status: StatusNeedsReview, Candidates: candidates}
+	}
+
+	only := candidates[0]
+	if only.Score < minConfidence {
+		return Result{Status: StatusNeedsReview, Candidates: candidates}
+	}
+
+	id := only.WorkoutKindID
+	score := only.Score
+	return Result{Status: StatusAssigned, WorkoutKindID: &id, Confidence: &score, Candidates: candidates}
+}