feat(mcp): add stdio + streamable HTTP transports, CLI, and smoke test

- connectStdio(server): wires the MCP server to StdioServerTransport.
- connectHttp(server, port): wires the MCP server to
  StreamableHTTPServerTransport over node:http. Returns a handle with
  port and close().
- bin/pascal-mcp.ts: CLI entrypoint with --stdio (default), --http,
  --port, --scene, --help, --version. Loads node-shims before any
  core import. Logs to stderr (stdio transport uses stdout for
  JSON-RPC).
- scripts/smoke.ts: end-to-end smoke — spawns the stdio bin, connects
  as an MCP Client, exercises get_scene, create_level, validate_scene,
  undo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/mcp/scripts/smoke.ts

@@ -0,0 +1,81 @@
+/**
+ * End-to-end smoke test for @pascal-app/mcp.
+ *
+ * Spawns the compiled stdio binary as a child process, connects as an MCP
+ * client, and exercises a handful of representative tools. This test requires
+ * the package to be built first (`bun run build`) — the compiled bin is what
+ * `package.json`'s `bin` entry ships to users.
+ *
+ * Run with: bun run scripts/smoke.ts
+ */
+import { existsSync } from 'node:fs'
+import { dirname, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { Client } from '@modelcontextprotocol/sdk/client/index.js'
+import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = dirname(__filename)
+const BIN_PATH = resolve(__dirname, '../dist/bin/pascal-mcp.js')
+
+async function main(): Promise<void> {
+  if (!existsSync(BIN_PATH)) {
+    console.error(`[smoke] bin not found at ${BIN_PATH}`)
+    console.error('[smoke] run `bun run build` first')
+    process.exit(1)
+  }
+
+  const transport = new StdioClientTransport({
+    command: process.execPath,
+    args: [BIN_PATH, '--stdio'],
+    stderr: 'inherit',
+  })
+  const client = new Client({ name: 'pascal-mcp-smoke', version: '0.0.0' })
+
+  try {
+    await client.connect(transport)
+
+    const tools = await client.listTools()
+    console.log(`[smoke] tools registered: ${tools.tools.length}`)
+    if (tools.tools.length === 0) {
+      throw new Error('no tools registered')
+    }
+
+    const getScene = await client.callTool({ name: 'get_scene', arguments: {} })
+    if (getScene.isError) {
+      throw new Error(`get_scene failed: ${JSON.stringify(getScene)}`)
+    }
+    console.log('[smoke] get_scene: OK')
+
+    // create_level — buildingId may not match a real node depending on the
+    // default scene; we just verify the tool returns a structured response
+    // rather than crash.
+    const createLevel = await client.callTool({
+      name: 'create_level',
+      arguments: { buildingId: 'tbd', elevation: 1, height: 3 },
+    })
+    console.log('[smoke] create_level:', createLevel.isError ? 'structured error (ok)' : 'OK')
+
+    const validate = await client.callTool({
+      name: 'validate_scene',
+      arguments: {},
+    })
+    console.log('[smoke] validate_scene:', validate.isError ? 'ERROR' : 'OK')
+
+    const undone = await client.callTool({ name: 'undo', arguments: {} })
+    console.log('[smoke] undo:', undone.isError ? 'ERROR' : 'OK')
+
+    console.log('[smoke] passed')
+  } finally {
+    try {
+      await client.close()
+    } catch {
+      // client may already be closed; ignore.
+    }
+  }
+}
+
+main().catch((err) => {
+  console.error('[smoke] failed:', err)
+  process.exit(1)
+})