Same root cause with GitHub Copilot CLI 1.0.105 (ACP Registry) on Windows, T3 Code desktop 0.1.4.
copilot --acp,session/new { cwd: <repo> }:available_commands_updatelists the repo skills from.github/skills,.claude/skillsand.agents/skills.- The same handshake with cwd = home lists none of them.
- Every
t3-code-provider-testsession in~/.copilot/session-staterecordscwd: <home>, so the composer list comes from the home-directory probe.
Two Copilot-specific details for the fix:
- Commands are stored per instance, not per project.
availableCommandsByInstanceis keyed byinstanceIdonly. When a live session publishesavailable_commands_update, that list replaces the one for every Copilot thread, so threads in different repos overwrite each other. Fixing the probe cwd alone leaves this open; the stored commands need a cwd or thread key as well. - Copilot advertises skills without
$. It sends skill names without a prefix (for examplemy-skill), sonormalizeAcpRegistryCommandsfiles them as slash commands. With Copilot the$list stays empty, even for user-level skills.