## Trigger
Wiring a skill / rule / MCP into Google Antigravity (`agy` CLI), or reviewing an
install/sync that claims "agy support" — especially when the target sits under
`~/.gemini`.

## Symptoms
- A sync script symlinks into `~/.gemini/config/` and labels it "Gemini CLI"
  (wrong: that dir is agy's global customization root).
- agy lacks skills/MCP that Claude/Codex have; `agy plugin list` = "No imported
  plugins"; `~/.gemini/config/mcp_config.json` is 0 bytes.

## Facts (verified 2026-07 on this WSL)
| Concern | Path / mechanism |
| :-- | :-- |
| CLI settings (model/permissions/trustedWorkspaces) | `~/.gemini/antigravity-cli/settings.json` |
| Global customization root | `~/.gemini/config/` (also holds agy `projects/` + `config.json`) |
| Global skills | `~/.gemini/config/skills/<name>/SKILL.md` |
| Global MCP servers | `~/.gemini/config/mcp_config.json` — standard `{"mcpServers":{...}}` |
| Per-workspace skills/rules/plugins | `<repo>/.agents/` (skills `.agents/skills/<name>/SKILL.md`, rules `.agents/AGENTS.md`) |
| Install plugin (skills+MCP+hooks) | `agy plugin install <path \| plugin@marketplace>` |
| `~/.gemini/settings.json` (sibling) | the deprecated standalone Gemini CLI — NOT agy |

## Fix
- **Skills**: symlink into `~/.gemini/config/skills/<name>/` (global) or
  `<repo>/.agents/skills/<name>/` (per-project). A superpowers/Claude-style
  plugin dir with a root `gemini-extension.json` installs via
  `agy plugin install <dir>` (→ processes skills + hooks + mcpServers).
- **MCP**: write `~/.gemini/config/mcp_config.json` as `{"mcpServers":{...}}`;
  keep secrets in an env file sourced by the server command, never inlined.
- **Do not** bake agy skills/MCP into a cross-device sync script — install them
  through agy's own `agy plugin` + `mcp_config.json` (same boundary Claude and
  Codex use for plugins/MCP).

## Reuse Rule
Before "fixing" a tool's install target, verify its real config-discovery root
empirically (`<tool> --help`, `<tool> plugin list/help`, `strings <binary>`, the
tool's shipped offline guide) — do not trust an agent's (or your own) asserted
"global root", especially when a config dir like `~/.gemini` is shared between a
live tool (Antigravity) and a deprecated one (Gemini CLI).