Gemini CLI

Gemini CLI has its own hook system, so it gets the full integration: hooks on session start, prompts, file writes and shell commands, the Comity MCP server, and a short instructions block in GEMINI.md.

Set up

cd your-repo
comity init --tools gemini
git add .gemini/settings.json GEMINI.md
git commit -m "Set up Comity for Gemini CLI"

Then trust the folder when Gemini CLI asks. Gemini fingerprints project hooks and warns before running new or changed ones: accept the comity hooks.

No token is written anywhere and none needs exporting: comity login on each machine is enough.

What init writes

.gemini/settings.json

Six hook events plus the MCP server. Your other settings, hooks and MCP servers are kept; rerunning init replaces only Comity's handlers. Shown for one event:

{
  "hooks": {
    "BeforeTool": [
      {
        "matcher": "write_file|replace|run_shell_command",
        "hooks": [
          {
            "name": "comity",
            "type": "command",
            "command": "node -e \"<launcher>\" hook --tool gemini --event BeforeTool",
            "timeout": 5000
          }
        ]
      }
    ]
  },
  "mcpServers": {
    "comity": { "command": "node", "args": ["-e", "<launcher>", "mcp"] }
  }
}

<launcher> is a one-line Node script that runs comity through the system shell, so the same file works on every OS and in every shell Gemini CLI uses (PowerShell on Windows, sh elsewhere). Node must be on PATH; the CLI needs it anyway. A hook exits quietly when comity isn't installed.

The MCP server is a local stdio process: comity mcp relays Gemini's MCP traffic to https://api.comity.so/mcp with the token from comity login (COMITY_TOKEN/COMITY_SERVER override it when set). The hooks use the same stored login.

GEMINI.md

A block between <!-- comity:start --> and <!-- comity:end --> with the agent instructions. The rest of the file is untouched; rerunning init updates only the block.

What your agent sees

• Session start and each prompt: the briefing as additionalContext.
• Before a write, replace or shell command: a block returns decision: "deny" with Comity's reason, which Gemini sends to the model as the tool error. Warnings are held and delivered with the next prompt or tool result (BeforeTool can't add context).
• After a write, replace or shell command: new conflicts, messages and answers appended to the tool result.

Verify

comity doctor

Expect gemini hooks all 6 events installed, gemini mcp configured in …/.gemini/settings.json and gemini rules GEMINI.md has the Comity block. In Gemini CLI, /hooks panel lists the comity hooks and /mcp lists comity.

Limits

• Gemini starts hooks and stdio MCP servers with a sanitized environment that can drop variables such as COMITY_TOKEN; both use your stored comity login, so log in on each machine.
• Only write_file, replace and run_shell_command are watched. Edits made by MCP tools or extensions aren't seen until Comity diffs the worktree on the next shell command or stop.
• Docs: Gemini CLI hooks, hooks reference, MCP servers.