Carry the source transcript into forks and cross-link fork points

internal/store/store.go

@@ -360,7 +360,11 @@ func (s *Store) CreateTask(ctx context.Context, t api.Task, frozen *FrozenWorkfl
 		if err != nil {
 			return err
 		}
-		return emit(api.Event{Kind: "task.created", ProjectId: &t.ProjectId, TaskId: &t.Id, Actor: actor, Payload: ToPayload(t)})
+		err = emit(api.Event{Kind: "task.created", ProjectId: &t.ProjectId, TaskId: &t.Id, Actor: actor, Payload: ToPayload(t)})
+		if err != nil || forkedFrom == "" {
+			return err
+		}
+		return emit(api.Event{Kind: "task.forked", ProjectId: &t.ProjectId, TaskId: &forkedFrom, Actor: actor, Payload: map[string]any{"fork": t.Id, "forked_at": forkedAt}})
 	})
 }
 
@@ -958,6 +962,41 @@ func (s *Store) TaskEvents(ctx context.Context, taskID string, after int64, limi
 	return scanEvents(rows)
 }
 
+func (s *Store) TranscriptEvents(ctx context.Context, taskID string, after int64, limit int) ([]api.Event, error) {
+	where := "task_id = ?"
+	args := []any{taskID}
+	for id := taskID; ; {
+		from := ""
+		at := 0
+		err := s.db.QueryRowContext(ctx, `SELECT forked_from, forked_at FROM tasks WHERE id = ?`, id).Scan(&from, &at)
+		if err != nil {
+			return nil, err
+		}
+		if from == "" {
+			break
+		}
+		cut := int64(0)
+		err = s.db.QueryRowContext(ctx, `
+			SELECT coalesce(max(seq), 0) FROM events
+			WHERE task_id = ? AND kind = 'snapshot.created' AND json_extract(payload, '$.n') = ?
+		`, from, at).Scan(&cut)
+		if err != nil {
+			return nil, err
+		}
+		where += " OR (task_id = ? AND seq <= ?)"
+		args = append(args, from, cut)
+		id = from
+	}
+	rows, err := s.db.QueryContext(ctx, `
+		SELECT `+eventColumns+`
+		FROM events WHERE (`+where+`) AND seq > ? ORDER BY seq LIMIT ?
+	`, append(args, after, limit)...)
+	if err != nil {
+		return nil, err
+	}
+	return scanEvents(rows)
+}
+
 func (s *Store) FirstPrompt(ctx context.Context, taskID string) (string, error) {
 	text := ""
 	err := s.db.QueryRowContext(ctx, `