Band MCP Server

/** * Server-side pagination emulator * - Exposes `emulatePagination(items, cursor, limit, maxUpstream)` * - Cursor is an opaque base64(json) containing { offset: number, seed?: string } * - If cursor invalid -> fallback to offset=0 * - nextCursor is generated when there are remaining items */ export interface EmulatedPage<T> { pageItems: T[]; nextCursor?: string | null; } export function encodeCursor(obj: unknown): string { try { return Buffer.from(JSON.stringify(obj)).toString("base64"); } catch { return ""; } } export function decodeCursor(cursor?: string): Record<string, unknown> | null { if (!cursor) return null; try { const s = Buffer.from(cursor, "base64").toString("utf8"); return JSON.parse(s); } catch { return null; } } export function emulatePagination<T>( items: T[], cursor?: string, limit?: number, maxUpstream = 200 ): EmulatedPage<T> { // Enforce max upstream size if (items.length > maxUpstream) { throw new Error( `Upstream returned too many items (${items.length}) exceeding maxUpstream=${maxUpstream}` ); } const parsed = decodeCursor(cursor); let offset = 0; if (parsed && typeof parsed.offset === "number" && parsed.offset >= 0) { offset = parsed.offset; } const safeLimit = typeof limit === "number" && limit > 0 ? Math.min(limit, 100) : 20; const pageItems = items.slice(offset, offset + safeLimit); let nextCursor: string | null = null; if (offset + pageItems.length < items.length) { nextCursor = encodeCursor({ offset: offset + pageItems.length, seed: Date.now(), }); } return { pageItems, nextCursor }; }