Prism MCP

Instructions

Implementation Reference

• src/tools/sessionMemoryHandlers.ts:909-960 (handler)

  The memoryHistoryHandler function implements the logic for the memory_history tool, fetching and formatting the project's memory timeline from storage.

  export async function memoryHistoryHandler(args: unknown) {
    if (!isMemoryHistoryArgs(args)) {
      throw new Error("Invalid arguments for memory_history");
    }
  
    const { project, limit = 10 } = args;
    const storage = await getStorage();
  
    console.error(`[memory_history] Fetching history for project="${project}" (limit=${limit})`);
  
    const history = await storage.getHistory(project, PRISM_USER_ID, Math.min(limit, 50));
  
    if (history.length === 0) {
      return {
        content: [{
          type: "text",
          text: `No memory history found for project "${project}".\n\n` +
            `History is automatically created each time you save a handoff.\n` +
            `Use session_save_handoff first, then check history again.`,
        }],
        isError: false,
      };
    }
  
    // Format timeline for LLM readability
    const timeline = history.map(h => {
      const summary = h.snapshot.last_summary || "(no summary)";
      const todos = h.snapshot.pending_todo?.length || 0;
      const branch = h.branch !== "main" ? ` [branch: ${h.branch}]` : "";
      return `  v${h.version} [${h.created_at}]${branch}\n    Summary: ${summary}\n    TODOs: ${todos} items`;
    }).join("\n\n");
  
    return {
      content: [{
        type: "text",
        text: `🕰️ Memory History for "${project}" (${history.length} snapshots):\n\n${timeline}\n\n` +
          `To revert to any version, use: memory_checkout with project="${project}" and target_version=<version number>.`,
      }],
      isError: false,
    };
  }
  
  // ─── Memory Checkout Handler (v2.0 — Time Travel) ────────────
  
  /**
   * Reverts a project's memory to a historical version — like Git revert.
   * The version number moves FORWARD (no data is lost), and the revert itself
   * is recorded in history so you can undo an undo.
   */
  export async function memoryCheckoutHandler(args: unknown) {
    if (!isMemoryCheckoutArgs(args)) {
      throw new Error("Invalid arguments for memory_checkout");

• src/tools/sessionMemoryDefinitions.ts:441-462 (schema)

  The MEMORY_HISTORY_TOOL object defines the schema, name, and description for the memory_history MCP tool.

  export const MEMORY_HISTORY_TOOL: Tool = {
    name: "memory_history",
    description:
      "View the timeline of past memory states for this project. " +
      "Use this BEFORE memory_checkout to find the correct version to revert to. " +
      "Shows version numbers, timestamps, and summaries of each saved state.",
    inputSchema: {
      type: "object",
      properties: {
        project: {
          type: "string",
          description: "Project identifier to view history for.",
        },
        limit: {
          type: "number",
          description: "Maximum number of history entries to return (default: 10, max: 50).",
          default: 10,
        },
      },
      required: ["project"],
    },
  };