minimal working version of backend and cli

backend/internal/db/repo.go

@@ -86,3 +86,29 @@ func (r *Repo) LatestParent(ctx context.Context, childID int64) (models.Node, bo
 	}
 	return n, true, nil
 }
+
+func (r *Repo) DeleteBranch(ctx context.Context, convID int64, name string) error {
+    _, err := r.db.ExecContext(ctx, `DELETE FROM branches WHERE conversation_id=? AND name=?`, convID, name)
+    return err
+}
+
+// ListBranches returns all branches for a conversation, newest first.
+func (r *Repo) ListBranches(ctx context.Context, convID int64) ([]models.Branch, error) {
+	rows, err := r.db.QueryContext(ctx, `
+		SELECT id, conversation_id, name, head_node_id
+		FROM branches
+		WHERE conversation_id=?
+		ORDER BY id DESC`, convID)
+	if err != nil { return nil, err }
+	defer rows.Close()
+
+	var out []models.Branch
+	for rows.Next() {
+		var b models.Branch
+		if err := rows.Scan(&b.ID, &b.ConversationID, &b.Name, &b.HeadNodeID); err != nil {
+			return nil, err
+		}
+		out = append(out, b)
+	}
+	return out, nil
+}