fix(mcp): cross-platform launcher for Windows/macOS/Linux

plugins/weixin/.mcp.json

@@ -1,8 +1,8 @@
 {
   "mcpServers": {
     "weixin": {
-      "command": "/bin/sh",
-      "args": ["-c", "PATH=\"$HOME/.bun/bin:$HOME/.volta/bin:$PATH\" bun run --cwd \"${CLAUDE_PLUGIN_ROOT}\" --shell=bun --silent start"]
+      "command": "node",
+      "args": ["${CLAUDE_PLUGIN_ROOT}/mcp-launch.cjs"]
     }
   }
 }

plugins/weixin/mcp-launch.cjs

@@ -0,0 +1,91 @@
+#!/usr/bin/env node
+/**
+ * Cross-platform launcher for the WeChat MCP server.
+ *
+ * Why this file exists:
+ *   Claude Code spawns MCP servers with a minimal environment. The previous
+ *   `.mcp.json` used a `bash -c "..."` wrapper to prepend `~/.bun/bin` and
+ *   `~/.volta/bin` to PATH (PR #14, then extended), which fixed macOS GUI
+ *   launches where the user's shell profile is not sourced. Windows, however,
+ *   typically has no POSIX shell on PATH, so that wrapper makes the plugin
+ *   fail to start on Windows entirely.
+ *
+ *   `.mcp.json` cannot conditionally branch on OS, so we centralize the
+ *   "find bun and start the server" logic here. Node.js is used as the
+ *   launcher runtime because it is the most widely available stable runtime
+ *   on developer machines across all three OSes.
+ */
+
+"use strict";
+
+const { spawn, spawnSync } = require("node:child_process");
+const { existsSync } = require("node:fs");
+const { constants, homedir, platform } = require("node:os");
+const { join } = require("node:path");
+
+const isWindows = platform() === "win32";
+const bunExe = isWindows ? "bun.exe" : "bun";
+
+/** Locate the bun executable across PATH and common install locations. */
+function findBun() {
+  const home = homedir();
+  const candidates = [
+    join(home, ".bun", "bin", bunExe),
+    join(home, ".volta", "bin", bunExe),
+  ];
+  for (const c of candidates) {
+    if (existsSync(c)) return c;
+  }
+  // Fall through to PATH lookup; spawn will report ENOENT if it is missing.
+  return bunExe;
+}
+
+const bun = findBun();
+const root = __dirname;
+
+// Step 1: install dependencies (idempotent, near-instant on no-op).
+//
+// stdout is redirected to our stderr (fd 2): MCP speaks JSON-RPC over the
+// launcher's stdout, and bun may print non-protocol lines like "Saved lockfile"
+// even with --no-summary, which would corrupt the stream.
+const install = spawnSync(bun, ["install", "--no-summary"], {
+  cwd: root,
+  stdio: ["ignore", 2, "inherit"],
+});
+if (install.error || install.status !== 0) {
+  const detail = install.error ? `: ${install.error.message}` : "";
+  process.stderr.write(
+    `[weixin] bun install failed (exit ${install.status ?? "?"})${detail}\n`,
+  );
+  process.exit(install.status ?? 1);
+}
+
+// Step 2: launch the MCP server with stdio inherited so the host can speak
+// MCP over stdin/stdout.
+const child = spawn(bun, ["server.ts"], {
+  cwd: root,
+  stdio: "inherit",
+});
+
+const forward = (sig) => {
+  if (!child.killed) child.kill(sig);
+};
+process.on("SIGINT", () => forward("SIGINT"));
+process.on("SIGTERM", () => forward("SIGTERM"));
+process.on("SIGHUP", () => forward("SIGHUP"));
+
+child.on("exit", (code, signal) => {
+  if (signal) {
+    // Don't re-raise the signal: we have SIGINT/SIGTERM/SIGHUP listeners
+    // installed, which override Node's default exit behavior and would leave
+    // the launcher hanging. Convey cause via the conventional 128+signum code.
+    const signum = constants.signals[signal] ?? 0;
+    process.exit(128 + signum);
+  }
+  process.exit(code ?? 0);
+});
+
+child.on("error", (err) => {
+  process.stderr.write(`[weixin] failed to spawn bun: ${err.message}\n`);
+  process.exit(1);
+});