feat: add packages/mex-mcp — MCP server for mex-agent

packages/mex-mcp/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "mex-mcp",
+  "version": "0.1.0",
+  "description": "MCP server for mex-agent — exposes check/log/timeline/heartbeat/read-file as native MCP tools",
+  "type": "module",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "bin": {
+    "mex-mcp": "./dist/index.js"
+  },
+  "scripts": {
+    "build": "tsup",
+    "dev": "tsup --watch",
+    "start": "node dist/index.js"
+  },
+  "dependencies": {
+    "@modelcontextprotocol/sdk": "^1.12.0",
+    "mex-agent": "workspace:*",
+    "zod": "^3.23.0"
+  },
+  "devDependencies": {
+    "@types/node": "^22.0.0",
+    "tsup": "^8.4.0",
+    "typescript": "^5.7.0"
+  }
+}

packages/mex-mcp/src/index.ts

@@ -0,0 +1,21 @@
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+import { registerCheckTool } from "./tools/check.js";
+import { registerLogTool } from "./tools/log.js";
+import { registerTimelineTool } from "./tools/timeline.js";
+import { registerHeartbeatTool } from "./tools/heartbeat.js";
+import { registerReadFileTool } from "./tools/read-file.js";
+
+const server = new McpServer({
+  name: "mex-mcp",
+  version: "0.1.0",
+});
+
+registerCheckTool(server);
+registerLogTool(server);
+registerTimelineTool(server);
+registerHeartbeatTool(server);
+registerReadFileTool(server);
+
+const transport = new StdioServerTransport();
+await server.connect(transport);

packages/mex-mcp/src/tools/check.ts

@@ -0,0 +1,32 @@
+import { z } from "zod";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { findConfig, runDriftCheck } from "mex-agent";
+
+export function registerCheckTool(server: McpServer) {
+  server.tool(
+    "mex_check",
+    "Run a drift check on the mex scaffold. Returns a DriftReport with a numeric score, issues list, and file count.",
+    {
+      projectRoot: z
+        .string()
+        .optional()
+        .describe("Absolute path to the project root. Defaults to cwd."),
+    },
+    async ({ projectRoot }) => {
+      const root = projectRoot ?? process.cwd();
+      const config = await findConfig(root);
+      if (!config) {
+        return {
+          content: [
+            {
+              type: "text",
+              text: JSON.stringify({ error: "No mex config found", projectRoot: root }),
+            },
+          ],
+        };
+      }
+      const report = await runDriftCheck(config);
+      return { content: [{ type: "text", text: JSON.stringify(report, null, 2) }] };
+    }
+  );
+}

packages/mex-mcp/src/tools/heartbeat.ts

@@ -0,0 +1,32 @@
+import { z } from "zod";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { findConfig, checkHeartbeat } from "mex-agent";
+
+export function registerHeartbeatTool(server: McpServer) {
+  server.tool(
+    "mex_heartbeat",
+    "Check the mex scaffold heartbeat. Returns ok status, stale files with age in days, and memory cleanup status.",
+    {
+      projectRoot: z
+        .string()
+        .optional()
+        .describe("Absolute path to the project root. Defaults to cwd."),
+    },
+    async ({ projectRoot }) => {
+      const root = projectRoot ?? process.cwd();
+      const config = await findConfig(root);
+      if (!config) {
+        return {
+          content: [
+            {
+              type: "text",
+              text: JSON.stringify({ error: "No mex config found", projectRoot: root }),
+            },
+          ],
+        };
+      }
+      const result = checkHeartbeat(config, new Date());
+      return { content: [{ type: "text", text: JSON.stringify(result, null, 2) }] };
+    }
+  );
+}

packages/mex-mcp/src/tools/log.ts

@@ -0,0 +1,51 @@
+import { z } from "zod";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { findConfig, appendEvent, readEvents, EVENT_KINDS } from "mex-agent";
+import type { EventKind } from "mex-agent";
+
+export function registerLogTool(server: McpServer) {
+  server.tool(
+    "mex_log",
+    `Append an agent event to the mex log, or read recent events. Valid kinds: ${EVENT_KINDS.join(", ")}.`,
+    {
+      projectRoot: z
+        .string()
+        .optional()
+        .describe("Absolute path to the project root. Defaults to cwd."),
+      action: z.enum(["read", "write"]).default("read"),
+      kind: z
+        .string()
+        .optional()
+        .describe(`Event kind for write (one of: ${EVENT_KINDS.join(", ")}).`),
+      summary: z.string().optional().describe("Human-readable event summary for write."),
+      limit: z.number().int().positive().optional().default(20),
+    },
+    async ({ projectRoot, action, kind, summary, limit }) => {
+      const root = projectRoot ?? process.cwd();
+      const config = await findConfig(root);
+      if (!config) {
+        return {
+          content: [
+            {
+              type: "text",
+              text: JSON.stringify({ error: "No mex config found", projectRoot: root }),
+            },
+          ],
+        };
+      }
+      if (action === "write") {
+        if (!kind || !summary) {
+          return {
+            content: [
+              { type: "text", text: JSON.stringify({ error: "kind and summary are required for write" }) },
+            ],
+          };
+        }
+        await appendEvent(config, { kind: kind as EventKind, summary });
+        return { content: [{ type: "text", text: JSON.stringify({ ok: true, kind, summary }) }] };
+      }
+      const events = await readEvents(config, { limit });
+      return { content: [{ type: "text", text: JSON.stringify(events, null, 2) }] };
+    }
+  );
+}

packages/mex-mcp/src/tools/read-file.ts

@@ -0,0 +1,51 @@
+import { z } from "zod";
+import { existsSync, readFileSync } from "node:fs";
+import { join } from "node:path";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { findConfig } from "mex-agent";
+
+export function registerReadFileTool(server: McpServer) {
+  server.tool(
+    "mex_read_file",
+    "Read a file from the mex scaffold directory (.mex/). Path is relative to .mex/ (e.g. 'AGENTS.md', 'context/stack.md').",
+    {
+      projectRoot: z
+        .string()
+        .optional()
+        .describe("Absolute path to the project root. Defaults to cwd."),
+      file: z
+        .string()
+        .describe("Path to the scaffold file relative to .mex/ (e.g. 'AGENTS.md', 'context/stack.md')."),
+    },
+    async ({ projectRoot, file }) => {
+      const root = projectRoot ?? process.cwd();
+      const config = await findConfig(root);
+      if (!config) {
+        return {
+          content: [
+            {
+              type: "text",
+              text: JSON.stringify({ error: "No mex config found", projectRoot: root }),
+            },
+          ],
+        };
+      }
+      const fullPath = join(config.scaffoldRoot, file);
+      if (!existsSync(fullPath)) {
+        return {
+          content: [
+            {
+              type: "text",
+              text: JSON.stringify({
+                error: `File not found: ${file}`,
+                scaffoldRoot: config.scaffoldRoot,
+              }),
+            },
+          ],
+        };
+      }
+      const content = readFileSync(fullPath, "utf-8");
+      return { content: [{ type: "text", text: content }] };
+    }
+  );
+}

packages/mex-mcp/src/tools/timeline.ts

@@ -0,0 +1,49 @@
+import { z } from "zod";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { findConfig, readEvents } from "mex-agent";
+
+export function registerTimelineTool(server: McpServer) {
+  server.tool(
+    "mex_timeline",
+    "Read the mex event timeline, optionally filtered by kind or date range. Good for understanding what an agent did and when.",
+    {
+      projectRoot: z
+        .string()
+        .optional()
+        .describe("Absolute path to the project root. Defaults to cwd."),
+      kind: z
+        .string()
+        .optional()
+        .describe("Filter by event kind (e.g. 'session_start', 'checkpoint', 'note')."),
+      since: z
+        .string()
+        .optional()
+        .describe("ISO 8601 timestamp — return only events at or after this time."),
+      limit: z.number().int().positive().optional().default(50),
+    },
+    async ({ projectRoot, kind, since, limit }) => {
+      const root = projectRoot ?? process.cwd();
+      const config = await findConfig(root);
+      if (!config) {
+        return {
+          content: [
+            {
+              type: "text",
+              text: JSON.stringify({ error: "No mex config found", projectRoot: root }),
+            },
+          ],
+        };
+      }
+      // over-fetch to allow client-side filtering without multiple round-trips
+      let events = await readEvents(config, { limit: limit * 4 });
+      if (kind) events = events.filter((e) => e.kind === kind);
+      if (since) {
+        const sinceMs = new Date(since).getTime();
+        events = events.filter((e) => new Date(e.timestamp).getTime() >= sinceMs);
+      }
+      return {
+        content: [{ type: "text", text: JSON.stringify(events.slice(0, limit), null, 2) }],
+      };
+    }
+  );
+}

packages/mex-mcp/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "dist"
+  },
+  "include": ["src"],
+  "exclude": ["node_modules", "dist"]
+}

packages/mex-mcp/tsup.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from "tsup";
+
+export default defineConfig({
+  entry: { index: "src/index.ts" },
+  format: ["esm"],
+  target: "node20",
+  outDir: "dist",
+  clean: true,
+  splitting: false,
+  sourcemap: true,
+  dts: true,
+  banner: { js: "#!/usr/bin/env node" },
+});