fix(filesystem): preserve CLI directories when MCP roots are available

src/filesystem/__tests__/cli-directories-precedence.test.ts

@@ -0,0 +1,271 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { spawn, ChildProcess } from 'child_process';
+import * as path from 'path';
+import * as fs from 'fs/promises';
+import * as os from 'os';
+
+const SERVER_PATH = path.join(__dirname, '..', 'dist', 'index.js');
+
+/**
+ * Sends a JSON-RPC message to the server via stdin (newline-delimited JSON).
+ */
+function sendMessage(proc: ChildProcess, message: object): void {
+  proc.stdin!.write(JSON.stringify(message) + '\n');
+}
+
+/**
+ * Reads newline-delimited JSON-RPC messages from the server stdout,
+ * collecting them until a message matching the predicate arrives or timeout is reached.
+ */
+function waitForMessage(
+  proc: ChildProcess,
+  predicate: (msg: any) => boolean,
+  timeoutMs = 5000
+): Promise<any> {
+  return new Promise((resolve, reject) => {
+    let buffer = '';
+    const timeout = setTimeout(() => {
+      cleanup();
+      reject(new Error('Timed out waiting for message'));
+    }, timeoutMs);
+
+    function cleanup() {
+      clearTimeout(timeout);
+      proc.stdout!.removeListener('data', onData);
+    }
+
+    function onData(chunk: Buffer) {
+      buffer += chunk.toString();
+      const lines = buffer.split('\n');
+      // Keep the last (possibly incomplete) line in the buffer
+      buffer = lines.pop() ?? '';
+      for (const line of lines) {
+        const trimmed = line.trim();
+        if (!trimmed) continue;
+        try {
+          const msg = JSON.parse(trimmed);
+          if (predicate(msg)) {
+            cleanup();
+            resolve(msg);
+            return;
+          }
+        } catch {
+          // skip malformed JSON
+        }
+      }
+    }
+
+    proc.stdout!.on('data', onData);
+  });
+}
+
+/**
+ * Spawns the filesystem server as a child process with the given CLI args,
+ * performs the MCP initialize handshake, and returns the process.
+ */
+async function startServer(
+  cliArgs: string[],
+  clientCapabilities: Record<string, any> = {}
+): Promise<{ proc: ChildProcess; stderr: string[] }> {
+  const stderrLines: string[] = [];
+  const proc = spawn('node', [SERVER_PATH, ...cliArgs], {
+    stdio: ['pipe', 'pipe', 'pipe'],
+  });
+
+  proc.stderr!.on('data', (data) => {
+    stderrLines.push(data.toString());
+  });
+
+  // Send initialize request
+  sendMessage(proc, {
+    jsonrpc: '2.0',
+    id: 1,
+    method: 'initialize',
+    params: {
+      protocolVersion: '2024-11-05',
+      capabilities: clientCapabilities,
+      clientInfo: { name: 'test-client', version: '1.0.0' },
+    },
+  });
+
+  // Wait for initialize response
+  await waitForMessage(proc, (msg) => msg.id === 1);
+
+  // Send initialized notification
+  sendMessage(proc, {
+    jsonrpc: '2.0',
+    method: 'notifications/initialized',
+  });
+
+  // Give the server a moment to process oninitialized
+  await new Promise((resolve) => setTimeout(resolve, 300));
+
+  return { proc, stderr: stderrLines };
+}
+
+function killProc(proc: ChildProcess): void {
+  proc.stdin!.end();
+  proc.kill('SIGTERM');
+}
+
+describe('CLI directories precedence over MCP roots', () => {
+  let testDir: string;
+  let cliDir: string;
+  let cliDir2: string;
+
+  beforeEach(async () => {
+    testDir = await fs.mkdtemp(path.join(os.tmpdir(), 'fs-cli-prec-test-'));
+    cliDir = path.join(testDir, 'cli-dir');
+    cliDir2 = path.join(testDir, 'cli-dir-2');
+    await fs.mkdir(cliDir, { recursive: true });
+    await fs.mkdir(cliDir2, { recursive: true });
+  });
+
+  afterEach(async () => {
+    await fs.rm(testDir, { recursive: true, force: true });
+  });
+
+  it('should ignore MCP roots on initialization when CLI directories are provided', async () => {
+    const { proc, stderr } = await startServer([cliDir], {
+      roots: { listChanged: true },
+    });
+
+    try {
+      const stderrText = stderr.join('');
+      expect(stderrText).toContain('CLI directories provided, ignoring MCP roots');
+
+      // Verify allowed directories are still the CLI-provided ones
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        id: 10,
+        method: 'tools/call',
+        params: {
+          name: 'list_allowed_directories',
+          arguments: {},
+        },
+      });
+
+      const response = await waitForMessage(proc, (msg) => msg.id === 10);
+      const text = response.result?.content?.[0]?.text ?? '';
+      const resolvedCliDir = await fs.realpath(cliDir);
+      expect(text).toContain(resolvedCliDir);
+    } finally {
+      killProc(proc);
+    }
+  });
+
+  it('should ignore roots/list_changed notifications when CLI directories are provided', async () => {
+    const { proc, stderr } = await startServer([cliDir], {
+      roots: { listChanged: true },
+    });
+
+    try {
+      // Send a roots/list_changed notification
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        method: 'notifications/roots/list_changed',
+      });
+
+      // Give the server time to process the notification
+      await new Promise((resolve) => setTimeout(resolve, 300));
+
+      const stderrText = stderr.join('');
+      expect(stderrText).toContain('Ignoring roots update: CLI directories take precedence');
+
+      // Verify allowed directories are still the CLI-provided ones
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        id: 20,
+        method: 'tools/call',
+        params: {
+          name: 'list_allowed_directories',
+          arguments: {},
+        },
+      });
+
+      const response = await waitForMessage(proc, (msg) => msg.id === 20);
+      const text = response.result?.content?.[0]?.text ?? '';
+      const resolvedCliDir = await fs.realpath(cliDir);
+      expect(text).toContain(resolvedCliDir);
+    } finally {
+      killProc(proc);
+    }
+  });
+
+  it('should use MCP roots when no CLI directories are provided (backward compat)', async () => {
+    const stderrLines: string[] = [];
+    const proc = spawn('node', [SERVER_PATH], {
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+
+    proc.stderr!.on('data', (data) => {
+      stderrLines.push(data.toString());
+    });
+
+    try {
+      // Send initialize with roots capability
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        id: 1,
+        method: 'initialize',
+        params: {
+          protocolVersion: '2024-11-05',
+          capabilities: { roots: { listChanged: true } },
+          clientInfo: { name: 'test-client', version: '1.0.0' },
+        },
+      });
+
+      await waitForMessage(proc, (msg) => msg.id === 1);
+
+      // Send initialized notification -- this triggers oninitialized which
+      // calls roots/list since the client advertised roots capability
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        method: 'notifications/initialized',
+      });
+
+      // The server will send a roots/list request; respond to it
+      const rootsRequest = await waitForMessage(
+        proc,
+        (msg) => msg.method === 'roots/list',
+        3000
+      );
+
+      const resolvedCliDir = await fs.realpath(cliDir);
+
+      // Respond with roots pointing to our test directory
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        id: rootsRequest.id,
+        result: {
+          roots: [{ uri: `file://${resolvedCliDir}`, name: 'Test Root' }],
+        },
+      });
+
+      // Wait for server to process roots
+      await new Promise((resolve) => setTimeout(resolve, 500));
+
+      const stderrText = stderrLines.join('');
+      expect(stderrText).toContain('Updated allowed directories from MCP roots');
+      expect(stderrText).not.toContain('CLI directories provided');
+
+      // Verify allowed directories now include the MCP root
+      sendMessage(proc, {
+        jsonrpc: '2.0',
+        id: 30,
+        method: 'tools/call',
+        params: {
+          name: 'list_allowed_directories',
+          arguments: {},
+        },
+      });
+
+      const response = await waitForMessage(proc, (msg) => msg.id === 30);
+      const text = response.result?.content?.[0]?.text ?? '';
+      expect(text).toContain(resolvedCliDir);
+    } finally {
+      proc.stdin!.end();
+      proc.kill('SIGTERM');
+    }
+  });
+});

src/filesystem/index.ts

@@ -89,6 +89,11 @@ if (accessibleDirectories.length === 0 && allowedDirectories.length > 0) {
 
 allowedDirectories = accessibleDirectories;
 
+// Track whether directories were explicitly provided via CLI arguments.
+// When CLI directories are provided, they take precedence over MCP roots
+// to prevent clients from overriding the user's explicit configuration.
+const cliDirectoriesProvided = args.length > 0 && allowedDirectories.length > 0;
+
 // Initialize the global allowedDirectories in lib.ts
 setAllowedDirectories(allowedDirectories);
 
@@ -715,7 +720,12 @@ async function updateAllowedDirectoriesFromRoots(requestedRoots: Root[]) {
 }
 
 // Handles dynamic roots updates during runtime, when client sends "roots/list_changed" notification, server fetches the updated roots and replaces all allowed directories with the new roots.
+// When CLI directories were provided, roots updates are ignored to preserve the explicit configuration.
 server.server.setNotificationHandler(RootsListChangedNotificationSchema, async () => {
+  if (cliDirectoriesProvided) {
+    console.error("Ignoring roots update: CLI directories take precedence");
+    return;
+  }
   try {
     // Request the updated roots list from the client
     const response = await server.server.listRoots();
@@ -728,10 +738,14 @@ server.server.setNotificationHandler(RootsListChangedNotificationSchema, async (
 });
 
 // Handles post-initialization setup, specifically checking for and fetching MCP roots.
+// CLI-provided directories take precedence over MCP roots to ensure explicit
+// user configuration is not overridden by the client's project roots.
 server.server.oninitialized = async () => {
   const clientCapabilities = server.server.getClientCapabilities();
 
-  if (clientCapabilities?.roots) {
+  if (cliDirectoriesProvided) {
+    console.error("CLI directories provided, ignoring MCP roots. Allowed directories:", allowedDirectories);
+  } else if (clientCapabilities?.roots) {
     try {
       const response = await server.server.listRoots();
       if (response && 'roots' in response) {