[BUG] Plugin install fails with EXDEV when /tmp is tmpfs

[discreteds]

Description

Plugin installation fails with EXDEV: cross-device link not permitted when /tmp is mounted as tmpfs (common default on modern Linux distros like Ubuntu, Fedora, Arch).

Steps to Reproduce

1. Have /tmp mounted as tmpfs (default on Ubuntu 25.10, many other distros)
2. Have ~/.claude on a different filesystem (ext4, btrfs, etc.)
3. Attempt to install any plugin via /plugins UI

Error Message

Error: Failed to install: EXDEV: cross-device link not permitted, 
rename '/home/user/.claude/plugins/cache/hiivmind-corpus-github' -> '/tmp/claude-plugin-temp-1766187024245'

Environment

• OS: Ubuntu 25.10 (Questing Quetzal)
• Kernel: 6.17.0-8-generic
• /tmp: tmpfs mount (tmpfs on /tmp type tmpfs)
• ~/.claude: ext4 on nvme (/dev/nvme0n1p2)
• Claude Code Version: Latest (1.0.40)

Root Cause

Node.js fs.rename() cannot move files across filesystem boundaries. The plugin installer uses rename() to move between ~/.claude/plugins/cache/ and /tmp/, which fails with EXDEV when these are on different mount points.

This is increasingly common as:

• Ubuntu 21.04+ defaults to tmpfs for /tmp
• Fedora, Arch, and others also use tmpfs /tmp by default
• Many users have /home on a separate partition

Workaround

Set TMPDIR to a location on the same filesystem as ~/.claude:

mkdir -p ~/.claude/tmp
TMPDIR=~/.claude/tmp claude

Or permanently in shell profile:

echo 'export TMPDIR="$HOME/.claude/tmp"' >> ~/.bashrc

Suggested Fix

Catch EXDEV error and fall back to copy+unlink pattern:

try {
  fs.renameSync(src, dest);
} catch (err) {
  if (err.code === 'EXDEV') {
    fs.cpSync(src, dest, { recursive: true });
    fs.rmSync(src, { recursive: true, force: true });
  } else {
    throw err;
  }
}

This is the standard pattern for handling cross-device moves in Node.js.

Related

• [BUG] Plugin install fails with EINVAL: invalid argument, rename - directory moved into itself #13503 - Similar rename issue (EINVAL, different root cause)

[rjmurillo]

Found the specific trigger. The error only happens with plugins using "source": "./.claude-plugin" in marketplace.json.

Tested on Ubuntu with tmpfs /tmp and ext4 /home:

• worktrunk@worktrunk - FAILS - uses "source": "./.claude-plugin"
• perplexity@perplexity-mcp-server - WORKS - uses "source": "./"
• claude-mem@thedotmack - WORKS - no source field
• all official plugins - WORK - no source field

So the bug is in the code path that handles subdirectory sources, not the root-level source path.

[discreteds]

Additional findings:

1. The source field is required - it cannot be removed as a workaround.

Per the official documentation, source is a required field for plugin entries:

Field	Type	Description
name	string	Plugin identifier
source	string|object	Where to fetch the plugin from

Removing it results in:

Failed to load marketplace: Invalid schema: plugins.0.source: Invalid input

2. "source": "./" also triggers the bug - not just "./.claude-plugin" as originally reported.

3. Observation: On my system, /tmp is tmpfs (RAM) while ~/.claude is on disk (different filesystems). Setting TMPDIR to a path on the same filesystem as ~/.claude allowed installation to succeed.

[SvenMeyer]

+1 - just happened to me as I have the same setup (/tmp) is tmpfs (RAM)