[fnzko]

What does this PR do?

Part of #277.
Depends on #349 (until it merges, only the last commit is new here).

OpenCode got its per-skill copies in .agents/skills/, which Antigravity CLI, Codex CLI, the Copilot CLI and Goose read too, so those taking a use --global plugin also found OpenCode's copy of its skills: Antigravity and Codex listed each twice, Copilot and Goose loaded the copy instead of the plugin.

OpenCode's copies now go to .opencode/skills/, which only OpenCode reads. A skill authored in .agents/skills/ gets no copy there, since OpenCode reads it in place. The next sync removes the copies left in .agents/skills/.

Verified by upgrading a project with OpenCode 1.17.12 next to Antigravity CLI 1.2.14 and Goose 1.55.0, and next to Codex CLI 0.159.3 and Copilot CLI 1.0.89 on #334: every agent lists each skill once.

Take into account:

• Codex and Copilot only take plugins from feat(agent-plugins): install global plugins for Codex CLI #334 and feat(agent-plugins): install global plugins for Copilot CLI #346 on.
• OpenCode treats .opencode/ as a config folder: it writes a self-ignoring .gitignore there and installs @opencode-ai/plugin into it; git status stays clean.

Disclosure questions

AI disclosure.

• The AI tool authored large parts of the code

[fnzko]

Folded into #332.