add-vendor-adapterlisted

# Add a New Vendor Adapter Use this skill when ynh needs to support a **new** AI coding CLI that has no `internal/vendor/<name>.go` yet — e.g. adding GitHub Copilot CLI, Gemini CLI, or any future vendor. If the vendor already has an adapter and you're just reacting to a spec change, use the `vendor-adapters` skill instead — it owns the per-vendor documentation links and format-mapping tables that this skill depends on. ## Before writing code: research 1. Research the vendor CLI's actual behavior — install method, config file layout (project-level and user-level), plugin/extension system (if any), skills/agents/rules/commands support, MCP support, hooks, instructions file, and CLI flags for interactive/non-interactive/initial-prompt launch. Cite official docs, not blog posts, wherever possible — vendor CLIs change fast and secondary sources go stale. 2. Add a new section to `.claude/skills/vendor-adapters/SKILL.md`'s documentation-links table and format-mapping tables for the new vendor. That skill is the single source of truth for vendor doc links — do not duplicate them here. 3. Decide the vendor's **launch strategy** up front — this drives most other decisions: - **Native plugin loading** (like Claude's `--plugin-dir`): `syscall.Exec`, no symlinks, `NeedsSymlinks() == false`. - **No native plugin loading** (like Codex, Cursor): symlink install into the project's vendor config dir + managed child process with signal forwardi