Troubleshooting on KnightLi Blog

Why Does a Codex Skill Exist in the Directory but Still Not Show Up?

Wed, 29 Apr 2026 11:18:00 +0800

This problem was easy to miss: several skills were already placed under ~/.codex/skills, but after opening a new Codex thread, the sidebar still showed only a small subset of them.

At first, it looked like a cache or indexing issue. The real cause was more specific: several SKILL.md files started with a UTF-8 BOM. Codex 0.111.0’s skill loader did not skip that byte sequence, so it misjudged the files as having no valid YAML front matter.

Symptom

The local directory contained these skills:

~/.codex/skills/git-commit-push/SKILL.md
~/.codex/skills/hugo-rsync-deploy/SKILL.md
~/.codex/skills/bilibili-speech-transcriber/SKILL.md
~/.codex/skills/product-cutout-normalize/SKILL.md

But after opening a new thread, the actually exposed skills were only:

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bilibili-speech-transcriber
product-cutout-normalize

In other words, a file existing on disk does not mean the current session can load it successfully. Codex parses the front matter of each SKILL.md first. If parsing fails, that skill is excluded directly.

Investigation

Starting a fresh session with codex exec showed a more direct error. In VS Code or other IDEs, these logs may not be visible:

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failed to load skill C:\Users\knightli\.codex\skills\git-commit-push\SKILL.md: missing YAML frontmatter delimited by ---
failed to load skill C:\Users\knightli\.codex\skills\hugo-rsync-deploy\SKILL.md: missing YAML frontmatter delimited by ---

Visually, these files seemed to have a normal header:

---
name: post-rewrite
description: ...
---

The real problem was at the byte level.

The beginning of a failing file was:

`1`	`EF-BB-BF-2D-2D-2D`

The beginning of a file that loaded correctly was:

`1`	`2D-2D-2D`

2D-2D-2D is ---. The preceding EF-BB-BF is the UTF-8 BOM.

Cause

In Codex 0.111.0, the skill loader expects the first byte of SKILL.md to be the first - in ---.

If the file starts with a UTF-8 BOM, the actual beginning becomes:

`1`	`BOM + ---`

So the loader thinks the file does not start with the front matter delimiter and reports:

`1`	`missing YAML frontmatter delimited by ---`

The skill content was not wrong, and the directory was not wrong either. A small encoding detail prevented the parser from recognizing the file.

Fix

Convert the affected SKILL.md files to UTF-8 without BOM.

In PowerShell, this can be done like this:

$paths = @(
  'C:\Users\knightli\.codex\skills\git-commit-push\SKILL.md',
  'C:\Users\knightli\.codex\skills\hugo-rsync-deploy\SKILL.md',
)

$utf8NoBom = New-Object System.Text.UTF8Encoding($false)

foreach ($p in $paths) {
  $text = [IO.File]::ReadAllText($p, [Text.Encoding]::UTF8)
  [IO.File]::WriteAllText($p, $text, $utf8NoBom)
}

After processing, the file header should change from:

`1`	`EF-BB-BF-2D-2D-2D`

to:

`1`	`2D-2D-2D`

Verification

After restarting a Codex session, the visible skills were restored to:

git-commit-push-zh
hugo-rsync-deploy
bilibili-speech-transcriber
product-cutout-normalize

If the sidebar still shows the old list, close the current Codex sidebar or window and reopen the project. The skill list is usually loaded when the session starts, so changes made in the middle of a session may not refresh immediately.

One Last Line

This kind of issue is easy to mistake for “Codex did not re-index” or “the skill was not installed correctly.”

When troubleshooting, check these three things first:

whether SKILL.md is really in the correct directory
whether the file has valid --- front matter at the top
whether the file is UTF-8 without BOM

The key in this case was the third point: the file looked fine, but its first byte was not -, so Codex did not treat it as a valid skill.

How to Check Whether a Tesla V100 Has ECC Errors

Thu, 23 Apr 2026 11:50:21 +0800

If you have a Tesla V100 on hand and want to do a basic health check first, ECC status is one of the most useful things to look at.

The most direct method is to inspect the card’s detailed information with nvidia-smi.

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nvidia-smi -q
# 查询第 0 块 GPU
nvidia-smi -q -i 0

Focus on the ECC Errors section.

On a card in normal condition, the four common groups of counters under ECC Errors should all be 0 or N/A. If any of them already show a non-zero value, it means the card has seen that type of ECC anomaly before, and you should further evaluate whether it is still suitable for continued use.

Reference output:

nvidia-smi -q
    ECC Mode
        Current                          : Enabled
        Pending                          : Enabled
    ECC Errors
        Volatile
            Single Bit
                Device Memory            : 0
                Register File            : 0
                L1 Cache                 : 0
                L2 Cache                 : 0
                Texture Memory           : N/A
                Texture Shared           : N/A
                CBU                      : N/A
                Total                    : 0
            Double Bit
                Device Memory            : 0
                Register File            : 0
                L1 Cache                 : 0
                L2 Cache                 : 0
                Texture Memory           : N/A
                Texture Shared           : N/A
                CBU                      : 0
                Total                    : 0
        Aggregate
            Single Bit
                Device Memory            : 0
                Register File            : 0
                L1 Cache                 : 0
                L2 Cache                 : 0
                Texture Memory           : N/A
                Texture Shared           : N/A
                CBU                      : N/A
                Total                    : 0
            Double Bit
                Device Memory            : 0
                Register File            : 0
                L1 Cache                 : 0
                L2 Cache                 : 0
                Texture Memory           : N/A
                Texture Shared           : N/A
                CBU                      : 0
                Total                    : 0
    Retired Pages

You can think of it like this:

Volatile is the error count for the current power cycle
Aggregate is the lifetime accumulated error count
Single Bit means correctable errors
Double Bit means uncorrectable errors, which are more serious

If you only want a quick screening rule, remember this:

Most items should be 0
N/A is normal for some not-applicable entries
If Double Bit or the total count is not 0, do not rely only on a seller’s verbal description; it is better to continue with fuller stress testing and stability checks

This does not replace a complete inspection, but it is enough for a first round of checks after a V100 arrives.

Windows Task Manager data stops updating: the refresh speed is usually set to Paused

Thu, 09 Apr 2026 18:15:53 +0800

Sometimes when you open Windows Task Manager, the data on the Processes or Performance tab appears frozen. CPU, memory, disk, or network values may stay unchanged for a long time. At first glance this can look like a system problem, but in reality running programs, network traffic, and resource usage are still changing normally.

In most cases, the system is not actually stuck. The more likely reason is that Task Manager’s refresh speed has been changed to Paused.

Symptoms

Common signs include:

CPU, memory, and other values on the Processes tab stop changing
Graphs on the Performance tab no longer update
Programs are clearly still running, but Task Manager looks frozen

Here is an example of what the issue looks like:

Cause

Task Manager lets you adjust the Update speed, with options such as High, Normal, Low, or Paused.

If this setting is changed to Paused, the statistics shown in the interface stop refreshing. That is why CPU, memory, or network information can appear to be completely frozen.

As shown below, this option is usually available from the View menu in Task Manager:

Fix

Check the following:

Open Task Manager
Click the View menu
Find Update speed
Check whether it is currently set to Paused
Change it back to Normal or High

After that, watch the Processes or Performance tab again. In most cases, the data will start updating normally right away.

Additional notes

If the data still does not refresh after switching back to Normal, check a few other possibilities:

Whether you are using system-tuning tools or third-party performance monitoring software
Whether you are connected through a remote session and the interface is not refreshing correctly
Whether Task Manager itself is stuck, in which case you can close it and open it again

That said, in most cases this issue is simply caused by Update speed being accidentally set to Paused, so checking that first is usually the fastest fix.