XDG_CONFIG_HOME support uses .copilot (dot-prefixed) subdirectory, violating XDG convention

[fuzzycode]

Describe the bug

When XDG_CONFIG_HOME is set, the CLI stores its config at $XDG_CONFIG_HOME/.copilot/ (e.g. ~/.config/.copilot/). Per the XDG Base
Directory Specification, directories under $XDG_CONFIG_HOME should not use a dot prefix — the dot is only needed under $HOME to
hide directories. The correct path should be $XDG_CONFIG_HOME/copilot/.

This also affects discoverability of skills and other config — the docs reference ~/.copilot/skills/ but don't mention that with
XDG_CONFIG_HOME set it becomes $XDG_CONFIG_HOME/.copilot/skills/, which is non-obvious and hard to debug (the directory is hidden
by default in file listings).

Affected version

v0.0.420

Steps to reproduce the behavior

Steps to reproduce:

1. Set XDG_CONFIG_HOME=~/.config
2. Create a skill at ~/.config/copilot/skills/my-skill/SKILL.md (correct XDG convention)
3. Run /skills list → 0 skills found
4. Move to ~/.config/.copilot/skills/ → skill is found

Expected behavior

CLI should use $XDG_CONFIG_HOME/copilot/ (no dot)

Additional context

Same issue applies to XDG_STATE_HOME — state is stored at $XDG_STATE_HOME/.copilot/ instead of $XDG_STATE_HOME/copilot/.

[WillEhrendreich]

I use XDG_CONFIG_HOME on windows, and it never sees my correct files until i tell it where to look, I had no idea what was going on, but that makes perfect sense.

[itaranto]

Even if the variables aren't defined, an XDG compliant application should default to ~/.config/, ~/.local/share/, ~/.cache/, etc.

[examon]

We addressed this starting in v1.0.1. The CLI no longer reads XDG_CONFIG_HOME or XDG_STATE_HOME for config and state directories. Instead, it uses a COPILOT_HOME environment variable (defaulting to ~/.copilot), and auto-migrates data from old XDG locations. Note that this took a different approach than requested - rather than fixing the dot-prefix under XDG dirs, XDG config/state support was replaced with COPILOT_HOME. The cache directory still respects XDG_CACHE_HOME and correctly uses copilot/ (no dot prefix). If you believe this isn't fully resolved, feel free to reopen this issue.

[oliv3r]

@examon as outlined in #1347 and #1954 the suggested fix is not a proper fix at all. Internally, you can check 'if COPILOT_HOME is set' use that, else 'if XDG_CONFIG_HOME is set' use that instead (XDG_CONFIG_HOME/copilot) and if none is set, use .copilot. Also note that the XDG_STATE_HOME (and XDG_DATA_HOME) dirs serve a different purpose! (config files vs state files vs data files, e.g. .local/share/copilot for skills/agents/etc vs .local/state/copilot for SQL stuff, etc etc., e.g. session files should be in state).

I bet copilot could solve this in 30 seconds :)