store: scope kind assignments, laps, and samples via activity ownership

None of these three tables gained their own user_id column -- they're
always accessed through a specific activity, so ownership is checked via a
join/subquery against activities.user_id instead.

backend/internal/store/assignments.go

@@ -28,8 +28,18 @@ type KindAssignment struct {
 	CreatedAt          string
 }
 
-// InsertKindAssignment appends a new assignment row for an activity.
+// InsertKindAssignment appends a new assignment row for an activity owned
-func (db *DB) InsertKindAssignment(ctx context.Context, a KindAssignment) (int64, error) {
+// by userID.
+func (db *DB) InsertKindAssignment(ctx context.Context, userID int64, a KindAssignment) (int64, error) {
+	var exists int
+	err := db.QueryRowContext(ctx, `SELECT 1 FROM activities WHERE id = ? AND user_id = ?`, a.ActivityID, userID).Scan(&exists)
+	if err == sql.ErrNoRows {
+		return 0, fmt.Errorf("insert kind assignment: activity %d not found for user %d", a.ActivityID, userID)
+	}
+	if err != nil {
+		return 0, fmt.Errorf("insert kind assignment for activity %d (user %d): %w", a.ActivityID, userID, err)
+	}
+
 	res, err := db.ExecContext(ctx, `
 		INSERT INTO kind_assignments (activity_id, workout_kind_id, assignment_source, status, confidence, candidate_kinds_json)
 		VALUES (?,?,?,?,?,?)`,
@@ -46,29 +56,37 @@ func scanKindAssignment(row interface{ Scan(...any) error }) (KindAssignment, er
 	return a, err
 }
 
-const kindAssignmentColumns = `id, activity_id, workout_kind_id, assignment_source, status, confidence, candidate_kinds_json, created_at`
+const kindAssignmentColumns = `a.id, a.activity_id, a.workout_kind_id, a.assignment_source, a.status, a.confidence, a.candidate_kinds_json, a.created_at`
 
-// CurrentAssignment returns the latest assignment for an activity, if any.
+// CurrentAssignment returns the latest assignment for an activity owned by
-func (db *DB) CurrentAssignment(ctx context.Context, activityID int64) (KindAssignment, bool, error) {
+// userID, if any.
-	row := db.QueryRowContext(ctx, `SELECT `+kindAssignmentColumns+` FROM current_kind_assignment WHERE activity_id = ?`, activityID)
+func (db *DB) CurrentAssignment(ctx context.Context, userID, activityID int64) (KindAssignment, bool, error) {
+	row := db.QueryRowContext(ctx, `
+		SELECT `+kindAssignmentColumns+`
+		FROM current_kind_assignment a
+		JOIN activities ON activities.id = a.activity_id
+		WHERE a.activity_id = ? AND activities.user_id = ?`, activityID, userID)
 	a, err := scanKindAssignment(row)
 	if err == sql.ErrNoRows {
 		return KindAssignment{}, false, nil
 	}
 	if err != nil {
-		return KindAssignment{}, false, fmt.Errorf("current assignment for activity %d: %w", activityID, err)
+		return KindAssignment{}, false, fmt.Errorf("current assignment for activity %d (user %d): %w", activityID, userID, err)
 	}
 	return a, true, nil
 }
 
-// ReviewQueue returns activities whose current assignment status is
+// ReviewQueue returns userID's activities whose current assignment status
-// needs_review, newest first.
+// is needs_review, newest first.
-func (db *DB) ReviewQueue(ctx context.Context) ([]KindAssignment, error) {
+func (db *DB) ReviewQueue(ctx context.Context, userID int64) ([]KindAssignment, error) {
 	rows, err := db.QueryContext(ctx, `
-		SELECT `+kindAssignmentColumns+` FROM current_kind_assignment
+		SELECT `+kindAssignmentColumns+`
-		WHERE status = ? ORDER BY created_at DESC`, AssignmentStatusNeedsReview)
+		FROM current_kind_assignment a
+		JOIN activities ON activities.id = a.activity_id
+		WHERE activities.user_id = ? AND a.status = ?
+		ORDER BY a.created_at DESC`, userID, AssignmentStatusNeedsReview)
 	if err != nil {
-		return nil, fmt.Errorf("review queue: %w", err)
+		return nil, fmt.Errorf("review queue for user %d: %w", userID, err)
 	}
 	defer rows.Close()
 
@@ -83,37 +101,44 @@ func (db *DB) ReviewQueue(ctx context.Context) ([]KindAssignment, error) {
 	return assignments, rows.Err()
 }
 
-// AllCurrentAssignments returns the latest assignment for every activity
+// AllCurrentAssignments returns the latest assignment for every one of
-// that has one, regardless of status or source -- the basis for deciding
+// userID's activities that has one, regardless of status or source -- the
-// which activities a global reclassify pass is allowed to touch.
+// basis for deciding which activities a global reclassify pass may touch.
-func (db *DB) AllCurrentAssignments(ctx context.Context) ([]KindAssignment, error) {
+func (db *DB) AllCurrentAssignments(ctx context.Context, userID int64) ([]KindAssignment, error) {
-	rows, err := db.QueryContext(ctx, `SELECT `+kindAssignmentColumns+` FROM current_kind_assignment`)
-	if err != nil {
-		return nil, fmt.Errorf("all current assignments: %w", err)
-	}
-	defer rows.Close()
-
-	assignments := []KindAssignment{}
-	for rows.Next() {
-		a, err := scanKindAssignment(rows)
-		if err != nil {
-			return nil, fmt.Errorf("scan kind assignment row: %w", err)
-		}
-		assignments = append(assignments, a)
-	}
-	return assignments, rows.Err()
-}
-
-// AssignmentsForKind returns every historical assignment where the given
-// workout kind was the resolved kind (regardless of source), oldest first --
-// the basis for progression-over-time charts.
-func (db *DB) AssignmentsForKind(ctx context.Context, workoutKindID int64) ([]KindAssignment, error) {
 	rows, err := db.QueryContext(ctx, `
-		SELECT `+kindAssignmentColumns+` FROM current_kind_assignment
+		SELECT `+kindAssignmentColumns+`
-		WHERE workout_kind_id = ? AND status = ? ORDER BY created_at ASC`,
+		FROM current_kind_assignment a
-		workoutKindID, AssignmentStatusAssigned)
+		JOIN activities ON activities.id = a.activity_id
+		WHERE activities.user_id = ?`, userID)
 	if err != nil {
-		return nil, fmt.Errorf("assignments for kind %d: %w", workoutKindID, err)
+		return nil, fmt.Errorf("all current assignments for user %d: %w", userID, err)
+	}
+	defer rows.Close()
+
+	assignments := []KindAssignment{}
+	for rows.Next() {
+		a, err := scanKindAssignment(rows)
+		if err != nil {
+			return nil, fmt.Errorf("scan kind assignment row: %w", err)
+		}
+		assignments = append(assignments, a)
+	}
+	return assignments, rows.Err()
+}
+
+// AssignmentsForKind returns every historical assignment (for userID's
+// activities) where the given workout kind was the resolved kind (regardless
+// of source), oldest first -- the basis for progression-over-time charts.
+func (db *DB) AssignmentsForKind(ctx context.Context, userID, workoutKindID int64) ([]KindAssignment, error) {
+	rows, err := db.QueryContext(ctx, `
+		SELECT `+kindAssignmentColumns+`
+		FROM current_kind_assignment a
+		JOIN activities ON activities.id = a.activity_id
+		WHERE activities.user_id = ? AND a.workout_kind_id = ? AND a.status = ?
+		ORDER BY a.created_at ASC`,
+		userID, workoutKindID, AssignmentStatusAssigned)
+	if err != nil {
+		return nil, fmt.Errorf("assignments for kind %d (user %d): %w", workoutKindID, userID, err)
 	}
 	defer rows.Close()
 

backend/internal/store/laps.go

@@ -2,6 +2,7 @@ package store
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 )
 
@@ -35,9 +36,19 @@ type Lap struct {
 	RawJSON           string
 }
 
-// ReplaceLaps deletes any existing laps for activityID and inserts the given
+// ReplaceLaps deletes any existing laps for activityID (owned by userID)
-// set, so re-syncing an activity's splits is idempotent.
+// and inserts the given set, so re-syncing an activity's splits is
-func (db *DB) ReplaceLaps(ctx context.Context, activityID int64, laps []Lap) error {
+// idempotent.
+func (db *DB) ReplaceLaps(ctx context.Context, userID, activityID int64, laps []Lap) error {
+	var exists int
+	err := db.QueryRowContext(ctx, `SELECT 1 FROM activities WHERE id = ? AND user_id = ?`, activityID, userID).Scan(&exists)
+	if err == sql.ErrNoRows {
+		return fmt.Errorf("replace laps: activity %d not found for user %d", activityID, userID)
+	}
+	if err != nil {
+		return fmt.Errorf("replace laps for activity %d (user %d): %w", activityID, userID, err)
+	}
+
 	tx, err := db.BeginTx(ctx, nil)
 	if err != nil {
 		return fmt.Errorf("begin replace laps tx: %w", err)
@@ -66,15 +77,19 @@ func (db *DB) ReplaceLaps(ctx context.Context, activityID int64, laps []Lap) err
 	return tx.Commit()
 }
 
-// LapsForActivity returns all laps for an activity, ordered by lap_index.
+// LapsForActivity returns all laps for an activity owned by userID,
-func (db *DB) LapsForActivity(ctx context.Context, activityID int64) ([]Lap, error) {
+// ordered by lap_index.
+func (db *DB) LapsForActivity(ctx context.Context, userID, activityID int64) ([]Lap, error) {
 	rows, err := db.QueryContext(ctx, `
-		SELECT id, activity_id, lap_index, avg_speed_mps,
+		SELECT laps.id, laps.activity_id, laps.lap_index, laps.avg_speed_mps,
-			intensity_type, hr_drift_bpm_per_min, hr_recovery_bpm_per_min,
+			laps.intensity_type, laps.hr_drift_bpm_per_min, laps.hr_recovery_bpm_per_min,
-			target_pace_low_mps, target_pace_high_mps, target_hr_low_bpm, target_hr_high_bpm, raw_json
+			laps.target_pace_low_mps, laps.target_pace_high_mps, laps.target_hr_low_bpm, laps.target_hr_high_bpm, laps.raw_json
-		FROM laps WHERE activity_id = ? ORDER BY lap_index`, activityID)
+		FROM laps
+		JOIN activities ON activities.id = laps.activity_id
+		WHERE laps.activity_id = ? AND activities.user_id = ?
+		ORDER BY laps.lap_index`, activityID, userID)
 	if err != nil {
-		return nil, fmt.Errorf("laps for activity %d: %w", activityID, err)
+		return nil, fmt.Errorf("laps for activity %d (user %d): %w", activityID, userID, err)
 	}
 	defer rows.Close()
 

backend/internal/store/reset_test.go

@@ -21,10 +21,10 @@ func TestResetAllSyncedData_DeletesActivitiesCascadesAndRewindsWatermark(t *test
 	if err != nil {
 		t.Fatalf("CreateWorkoutKind: %v", err)
 	}
-	if err := db.ReplaceLaps(ctx, activityID, []Lap{{LapIndex: 1}}); err != nil {
+	if err := db.ReplaceLaps(ctx, userID, activityID, []Lap{{LapIndex: 1}}); err != nil {
 		t.Fatalf("ReplaceLaps: %v", err)
 	}
-	if _, err := db.InsertKindAssignment(ctx, KindAssignment{
+	if _, err := db.InsertKindAssignment(ctx, userID, KindAssignment{
 		ActivityID: activityID, WorkoutKindID: &kindID, AssignmentSource: AssignmentSourceRuleEngine,
 		Status: AssignmentStatusAssigned, CandidateKindsJSON: "[]",
 	}); err != nil {
@@ -45,14 +45,14 @@ func TestResetAllSyncedData_DeletesActivitiesCascadesAndRewindsWatermark(t *test
 	if len(activities) != 0 {
 		t.Errorf("expected 0 activities after reset, got %d", len(activities))
 	}
-	laps, err := db.LapsForActivity(ctx, activityID)
+	laps, err := db.LapsForActivity(ctx, userID, activityID)
 	if err != nil {
 		t.Fatalf("LapsForActivity: %v", err)
 	}
 	if len(laps) != 0 {
 		t.Errorf("expected laps to cascade-delete, got %d", len(laps))
 	}
-	if _, ok, err := db.CurrentAssignment(ctx, activityID); err != nil || ok {
+	if _, ok, err := db.CurrentAssignment(ctx, userID, activityID); err != nil || ok {
 		t.Errorf("expected kind assignment to cascade-delete, ok=%v err=%v", ok, err)
 	}
 

backend/internal/store/samples.go

@@ -2,6 +2,7 @@ package store
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 )
 
@@ -15,9 +16,19 @@ type Sample struct {
 	ElevationM     *float64
 }
 
-// ReplaceActivitySamples deletes any existing samples for activityID and
+// ReplaceActivitySamples deletes any existing samples for activityID (owned
-// bulk-inserts the given set, so re-syncing an activity's details is idempotent.
+// by userID) and bulk-inserts the given set, so re-syncing an activity's
-func (db *DB) ReplaceActivitySamples(ctx context.Context, activityID int64, samples []Sample) error {
+// details is idempotent.
+func (db *DB) ReplaceActivitySamples(ctx context.Context, userID, activityID int64, samples []Sample) error {
+	var exists int
+	err := db.QueryRowContext(ctx, `SELECT 1 FROM activities WHERE id = ? AND user_id = ?`, activityID, userID).Scan(&exists)
+	if err == sql.ErrNoRows {
+		return fmt.Errorf("replace activity samples: activity %d not found for user %d", activityID, userID)
+	}
+	if err != nil {
+		return fmt.Errorf("replace activity samples for activity %d (user %d): %w", activityID, userID, err)
+	}
+
 	tx, err := db.BeginTx(ctx, nil)
 	if err != nil {
 		return fmt.Errorf("begin replace samples tx: %w", err)
@@ -44,13 +55,18 @@ func (db *DB) ReplaceActivitySamples(ctx context.Context, activityID int64, samp
 	return tx.Commit()
 }
 
-// SamplesForActivity returns all samples for an activity, ordered by elapsed_seconds.
+// SamplesForActivity returns all samples for an activity owned by userID,
-func (db *DB) SamplesForActivity(ctx context.Context, activityID int64) ([]Sample, error) {
+// ordered by elapsed_seconds.
+func (db *DB) SamplesForActivity(ctx context.Context, userID, activityID int64) ([]Sample, error) {
 	rows, err := db.QueryContext(ctx, `
-		SELECT elapsed_seconds, timestamp_ms, heart_rate, speed_mps, distance_m, elevation_m
+		SELECT activity_samples.elapsed_seconds, activity_samples.timestamp_ms, activity_samples.heart_rate,
-		FROM activity_samples WHERE activity_id = ? ORDER BY elapsed_seconds`, activityID)
+			activity_samples.speed_mps, activity_samples.distance_m, activity_samples.elevation_m
+		FROM activity_samples
+		JOIN activities ON activities.id = activity_samples.activity_id
+		WHERE activity_samples.activity_id = ? AND activities.user_id = ?
+		ORDER BY activity_samples.elapsed_seconds`, activityID, userID)
 	if err != nil {
-		return nil, fmt.Errorf("samples for activity %d: %w", activityID, err)
+		return nil, fmt.Errorf("samples for activity %d (user %d): %w", activityID, userID, err)
 	}
 	defer rows.Close()
 

backend/internal/store/store_test.go

@@ -143,7 +143,7 @@ func TestKindAssignment_AppendOnlyHistoryAndCurrentView(t *testing.T) {
 	}
 
 	// First: rule engine says needs_review (ambiguous).
-	if _, err := db.InsertKindAssignment(ctx, KindAssignment{
+	if _, err := db.InsertKindAssignment(ctx, userID, KindAssignment{
 		ActivityID:         activityID,
 		AssignmentSource:   AssignmentSourceRuleEngine,
 		Status:             AssignmentStatusNeedsReview,
@@ -152,7 +152,7 @@ func TestKindAssignment_AppendOnlyHistoryAndCurrentView(t *testing.T) {
 		t.Fatalf("InsertKindAssignment (rule engine): %v", err)
 	}
 
-	queue, err := db.ReviewQueue(ctx)
+	queue, err := db.ReviewQueue(ctx, userID)
 	if err != nil {
 		t.Fatalf("ReviewQueue: %v", err)
 	}
@@ -161,7 +161,7 @@ func TestKindAssignment_AppendOnlyHistoryAndCurrentView(t *testing.T) {
 	}
 
 	// Then: user manually resolves it.
-	if _, err := db.InsertKindAssignment(ctx, KindAssignment{
+	if _, err := db.InsertKindAssignment(ctx, userID, KindAssignment{
 		ActivityID:       activityID,
 		WorkoutKindID:    &kindID,
 		AssignmentSource: AssignmentSourceManual,
@@ -170,7 +170,7 @@ func TestKindAssignment_AppendOnlyHistoryAndCurrentView(t *testing.T) {
 		t.Fatalf("InsertKindAssignment (manual): %v", err)
 	}
 
-	queue, err = db.ReviewQueue(ctx)
+	queue, err = db.ReviewQueue(ctx, userID)
 	if err != nil {
 		t.Fatalf("ReviewQueue after resolve: %v", err)
 	}
@@ -178,7 +178,7 @@ func TestKindAssignment_AppendOnlyHistoryAndCurrentView(t *testing.T) {
 		t.Fatalf("expected 0 items in review queue after manual resolve, got %d", len(queue))
 	}
 
-	current, ok, err := db.CurrentAssignment(ctx, activityID)
+	current, ok, err := db.CurrentAssignment(ctx, userID, activityID)
 	if err != nil || !ok {
 		t.Fatalf("CurrentAssignment: ok=%v err=%v", ok, err)
 	}
@@ -195,7 +195,7 @@ func TestKindAssignment_AppendOnlyHistoryAndCurrentView(t *testing.T) {
 		t.Errorf("expected 2 historical assignment rows (rule engine + manual), got %d", historyCount)
 	}
 
-	forKind, err := db.AssignmentsForKind(ctx, kindID)
+	forKind, err := db.AssignmentsForKind(ctx, userID, kindID)
 	if err != nil {
 		t.Fatalf("AssignmentsForKind: %v", err)
 	}
@@ -225,15 +225,15 @@ func TestReplaceLapsIsIdempotent(t *testing.T) {
 		{LapIndex: 1, RawJSON: "{}"},
 		{LapIndex: 2, RawJSON: "{}"},
 	}
-	if err := db.ReplaceLaps(ctx, activityID, laps); err != nil {
+	if err := db.ReplaceLaps(ctx, userID, activityID, laps); err != nil {
 		t.Fatalf("ReplaceLaps (first): %v", err)
 	}
 	// Re-sync with a different set (e.g. corrected data) should fully replace, not append.
-	if err := db.ReplaceLaps(ctx, activityID, laps[:1]); err != nil {
+	if err := db.ReplaceLaps(ctx, userID, activityID, laps[:1]); err != nil {
 		t.Fatalf("ReplaceLaps (second): %v", err)
 	}
 
-	got, err := db.LapsForActivity(ctx, activityID)
+	got, err := db.LapsForActivity(ctx, userID, activityID)
 	if err != nil {
 		t.Fatalf("LapsForActivity: %v", err)
 	}
@@ -309,7 +309,7 @@ func TestForeignKeyEnforcementPostMigration(t *testing.T) {
 	}
 
 	// Inserting a kind_assignment with a valid FK reference should succeed.
-	assignmentID, err := db.InsertKindAssignment(ctx, KindAssignment{
+	assignmentID, err := db.InsertKindAssignment(ctx, userID, KindAssignment{
 		ActivityID:       activityID,
 		WorkoutKindID:    &seedKindID,
 		AssignmentSource: AssignmentSourceManual,
@@ -325,7 +325,7 @@ func TestForeignKeyEnforcementPostMigration(t *testing.T) {
 	// Inserting a kind_assignment with a nonexistent workout_kind_id should
 	// be rejected by the FK constraint, proving FK enforcement is ON.
 	nonexistentKindID := int64(999999)
-	_, err = db.InsertKindAssignment(ctx, KindAssignment{
+	_, err = db.InsertKindAssignment(ctx, userID, KindAssignment{
 		ActivityID:       activityID,
 		WorkoutKindID:    &nonexistentKindID,
 		AssignmentSource: AssignmentSourceManual,
@@ -568,6 +568,38 @@ func TestRebuildMigrationsPreserveForeignKeyReferences(t *testing.T) {
 	}
 }
 
+func TestCurrentAssignment_ScopedToOwningUser(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+	userA, err := db.ProvisionUser(ctx, "sub-a", "A")
+	if err != nil {
+		t.Fatalf("ProvisionUser(a): %v", err)
+	}
+	userB, err := db.ProvisionUser(ctx, "sub-b", "B")
+	if err != nil {
+		t.Fatalf("ProvisionUser(b): %v", err)
+	}
+
+	activityID, err := db.UpsertActivity(ctx, userA, Activity{GarminActivityID: 1, StartTimeUTC: "2026-07-11 05:00:00", RawJSON: "{}"})
+	if err != nil {
+		t.Fatalf("UpsertActivity: %v", err)
+	}
+	if _, err := db.InsertKindAssignment(ctx, userA, KindAssignment{
+		ActivityID: activityID, AssignmentSource: AssignmentSourceRuleEngine, Status: AssignmentStatusNeedsReview, CandidateKindsJSON: "[]",
+	}); err != nil {
+		t.Fatalf("InsertKindAssignment: %v", err)
+	}
+
+	if _, found, err := db.CurrentAssignment(ctx, userB, activityID); err != nil || found {
+		t.Fatalf("expected userB to not see userA's activity assignment, found=%v err=%v", found, err)
+	}
+	if _, err := db.InsertKindAssignment(ctx, userB, KindAssignment{
+		ActivityID: activityID, AssignmentSource: AssignmentSourceManual, Status: AssignmentStatusAssigned, CandidateKindsJSON: "[]",
+	}); err == nil {
+		t.Fatal("expected InsertKindAssignment to reject an activity that doesn't belong to userB")
+	}
+}
+
 func contains(s string, substrs ...string) bool {
 	lower := strings.ToLower(s)
 	for _, substr := range substrs {