`list_projects` MCP tool fails with `EBADF: bad file descriptor, lstat '/dev/fd/12'` when MCP roots include `/dev/fd/*`

[midthun]

Command

other

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

The list_projects MCP tool can fail immediately with:

EBADF: bad file descriptor, lstat '/dev/fd/12'

This appears to happen when the MCP host provides a root path backed by a file descriptor such as /dev/fd/12. For me specifically this happens in Codex Mac app.

From reading the tool source, createListProjectsHandler() collects roots from MCP listRoots() and then passes them into findAngularJsonFiles(). The implementation assumes those roots are normal filesystem directories and performs operations such as stat(rootDir), realpathSync(root), and directory traversal. When the root is a descriptor-backed path like /dev/fd/12, those calls can fail with EBADF.

The tool currently ignores some filesystem errors (EACCES, EPERM, ENOENT, EBUSY) but not EBADF, so the tool aborts instead of skipping the invalid root or falling back gracefully.

This looks like a robustness issue in the tool: even if an MCP client provides an unusual root, the tool should not hard-fail during workspace discovery.

Minimal Reproduction

Minimal Reproduction

1. Run the Angular CLI MCP tool list_projects in an environment where the MCP host exposes roots that resolve to /dev/fd/<n> rather than stable directory paths. I use Codex mac app.
2. Invoke the tool without arguments.
3. Observe that it fails with: EBADF: bad file descriptor, lstat '/dev/fd/12'

Relevant code path from the tool source:

• createListProjectsHandler() obtains searchRoots from MCP listRoots()
• roots are normalized with fileURLToPath(...)
• roots are passed to findAngularJsonFiles(root, realAllowedRoots)
• findAngularJsonFiles() calls stat(rootDir)
• root resolution also uses ealpathSync(r) for allowed roots

Because the root is not a stable directory path, traversal fails before any Angular workspace parsing happens.

Exception or Error

`EBADF: bad file descriptor, lstat '/dev/fd/12'`

Your Environment

_                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/
    

Angular CLI       : 21.2.3
Angular           : 21.2.5
Node.js           : 24.10.0
Package Manager   : npm 11.12.1
Operating System  : darwin arm64

┌───────────────────────────────────┬───────────────────┬───────────────────┐
│ Package                           │ Installed Version │ Requested Version │
├───────────────────────────────────┼───────────────────┼───────────────────┤
│ @angular/animations               │ 21.2.5            │ ^21.2.0           │
│ @angular/build                    │ 21.2.3            │ ^21.2.0           │
│ @angular/cdk                      │ 21.2.3            │ ^21.2.0           │
│ @angular/cli                      │ 21.2.3            │ ^21.2.0           │
│ @angular/common                   │ 21.2.5            │ ^21.2.0           │
│ @angular/compiler                 │ 21.2.5            │ ^21.2.0           │
│ @angular/compiler-cli             │ 21.2.5            │ ^21.2.0           │
│ @angular/core                     │ 21.2.5            │ ^21.2.0           │
│ @angular/forms                    │ 21.2.5            │ ^21.2.0           │
│ @angular/material                 │ 21.2.3            │ ^21.2.0           │
│ @angular/platform-browser         │ 21.2.5            │ ^21.2.0           │
│ @angular/platform-browser-dynamic │ 21.2.5            │ ^21.2.0           │
│ @angular/router                   │ 21.2.5            │ ^21.2.0           │
│ @angular/service-worker           │ 21.2.5            │ ^21.2.0           │
│ ng-packagr                        │ 21.2.1            │ ^21.2.0           │
│ rxjs                              │ 7.8.2             │ ^7.8.2            │
│ typescript                        │ 5.9.3             │ ~5.9.3            │
│ vitest                            │ 4.1.0             │ ^4.0.18           │
└───────────────────────────────────┴───────────────────┴───────────────────┘

Anything else relevant?

No response