[bug]: skill update fails with EPERM rename on Windows when the skill dir is locked (agent junction target)

The issue is in the skill update logic, likely in a file handling the rename operation for skill directories. Look for the code that performs the rename (e.g., in a skill manager or updater module) and the error handling for EPERM on Windows. The fix involves changing the update strategy to avoid renaming a locked directory, perhaps by replacing contents in place or using a copy+delete fallback. Test the fix on Windows with an agent holding a directory handle to ensure the update succeeds.

CLI version

2.0.1

Skill version (optional)

1.28.0

Node version

v24.18.0

OS

Windows 10.0.26200 (x64), PowerShell 5.1

Region

cn

Command to reproduce

bl skill update

Expected behavior

All installed skills are updated to the latest registry version, keeping the CLI and its skills version-aligned.

Actual behavior

bl skill update renames each installed skill directory to <name>.old-<timestamp> before writing the new version. On Windows, when another process (the agent host) holds a directory handle on the skill dir, that rename fails with EPERM. 7 of 10 installed skills were left at 1.28.0 while the CLI had already been auto-upgraded to 2.0.1, and the command exited with code 1.

Full output

Error:       7 skill(s) failed to update
Hint:        Check the reason for failed skills in the output; network failures can be retried with bl skill update
Exit code:   1

{
  "registry": "https://bailian-wiki.oss-cn-hangzhou.aliyuncs.com/skills",
  "skills": [
    {
      "name": "bailian-cli",
      "status": "failed",
      "reason": "EPERM: operation not permitted, rename 'C:\\Users\\<user>\\.bailian\\skills\\bailian-cli' -> 'C:\\Users\\<user>\\.bailian\\skills\\bailian-cli.old-1790157014446'"
    },
    {
      "name": "bailian-gen",
      "status": "failed",
      "reason": "EPERM: operation not permitted, rename 'C:\\Users\\<user>\\.bailian\\skills\\bailian-gen' -> 'C:\\Users\\<user>\\.bailian\\skills\\bailian-gen.old-1790157014456'"
    },
    {
      "name": "bailian-protocol",
      "status": "failed",
      "reason": "EPERM: operation not permitted, rename 'C:\\Users\\<user>\\.bailian\\skills\\bailian-protocol' -> '...old-1790157015136'"
    },
    ... (same EPERM rename failure for bailian-finetune, bailian-managed-agent, bailian-sandbox, bailian-docs-llm-wiki)
  ]
}

JSON error (optional)

Already tried

• bl update and skill version aligned with CLI
• bl auth status OK for this command
• Different network / region — still reproduces

How often does this happen?

Always

How was bl invoked?

Agent (Cursor, Claude, etc.)

Notes (optional)

Isolation performed on the same machine (all reproduced, 2/2 runs):

• ACLs are fine (FullControl); renaming a brand-new dir in the same parent -> OK
• Copying a skill dir and renaming the copy -> OK
• Creating a new junction to a fresh dir and renaming its target -> OK (the junction itself does not block)
• Renaming the pre-existing skill dirs -> Access denied (reproducible)
• Creating/deleting files inside the locked dir -> OK
• Windows Restart Manager reports no open FILE handles (directory handles are not visible to it)
  => consistent with a directory handle held by another process.

Workaround that works: release the handles (restart the agent host) and run bl skill update inside that window -> all 7 skills updated successfully (exit 0).

Suggested fix:

• Do not rely on renaming the target directory: replace contents in place, or fall back to copy+delete with retry on EPERM/EBUSY.
• Or detach the agent-dir junction/link before the swap, then re-link after.
• On failure, emit an actionable hint (e.g. close agent hosts holding the skill dirs).

Repro details: skills are stored once at C:\Users<user>.bailian\skills<name> and junctioned into the agent skill root C:\Users<user>.openclaw\skills<name>.

Related: #200 (opt-out of silent auto-update + automatic skill sync) - same code path.
Redaction: API keys/tokens removed; username replaced with .