feat: add gemini adapter (#26)

Author: tsuno08

README.md

@@ -322,7 +322,7 @@ gtr.editor.default = cursor
 ### AI Tool Settings
 
 ```bash
-# Default AI tool: none (or aider, claude, codex, cursor, continue, opencode)
+# Default AI tool: none (or aider, claude, codex, continue, cursor, gemini, opencode)
 gtr.ai.default = none
 ```
 
@@ -333,8 +333,9 @@ gtr.ai.default = none
 | **[Aider](https://aider.chat)**                   | `pip install aider-chat`                          | Pair programming, edit files with AI | `git gtr config set gtr.ai.default aider`    |
 | **[Claude Code](https://claude.com/claude-code)** | Install from claude.com                           | Terminal-native coding agent         | `git gtr config set gtr.ai.default claude`   |
 | **[Codex CLI](https://github.com/openai/codex)**  | `npm install -g @openai/codex`                    | OpenAI coding assistant              | `git gtr config set gtr.ai.default codex`    |
-| **[Cursor](https://cursor.com)**                  | Install from cursor.com                           | AI-powered editor with CLI agent     | `git gtr config set gtr.ai.default cursor`   |
 | **[Continue](https://continue.dev)**              | See [docs](https://docs.continue.dev/cli/install) | Open-source coding agent             | `git gtr config set gtr.ai.default continue` |
+| **[Cursor](https://cursor.com)**                  | Install from cursor.com                           | AI-powered editor with CLI agent     | `git gtr config set gtr.ai.default cursor`   |
+| **[Gemini](https://github.com/google-gemini/gemini-cli)** | `npm install -g @google/gemini-cli`                                | Open-source AI coding assistant powered by Google Gemini         | `git gtr config set gtr.ai.default gemini`   |
 | **[OpenCode](https://opencode.ai)**               | Install from opencode.ai                          | AI coding assistant                  | `git gtr config set gtr.ai.default opencode` |
 
 **Examples:**

adapters/ai/gemini.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Gemini CLI adapter
+
+# Check if Gemini is available
+ai_can_start() {
+  command -v gemini >/dev/null 2>&1
+}
+
+# Start Gemini in a directory
+# Usage: ai_start path [args...]
+ai_start() {
+  local path="$1"
+  shift
+
+  if ! ai_can_start; then
+    log_error "Gemini CLI not found. Install with: npm install -g @google/gemini-cli"
+    log_info "Or: brew install gemini-cli"
+    log_info "See https://github.com/google-gemini/gemini-cli for more info"
+    return 1
+  fi
+
+  if [ ! -d "$path" ]; then
+    log_error "Directory not found: $path"
+    return 1
+  fi
+
+  # Change to the directory and run gemini with any additional arguments
+  (cd "$path" && gemini "$@")
+}

bin/gtr

@@ -965,7 +965,7 @@ load_ai_adapter() {
 
   if ! command -v "$cmd_name" >/dev/null 2>&1; then
     log_error "AI tool '$ai_tool' not found"
-    log_info "Built-in adapters: aider, claude, codex, cursor, continue, opencode"
+    log_info "Built-in adapters: aider, claude, codex, continue, cursor, gemini, opencode"
     log_info "Or use any AI tool command available in your PATH (e.g., bunx, gpt)"
     exit 1
   fi
@@ -1124,8 +1124,8 @@ CONFIGURATION OPTIONS:
                            webstorm, vim, nvim, emacs, sublime, nano,
                            atom, none
   gtr.ai.default           Default AI tool
-                           Options: aider, claude, codex, cursor,
-                           continue, opencode, none
+                           Options: aider, claude, codex, continue,
+                           cursor, gemini, opencode, none
   gtr.copy.include         Files to copy (multi-valued)
   gtr.copy.exclude         Files to exclude (multi-valued)
   gtr.copy.includeDirs     Directories to copy (multi-valued)

completions/_git-gtr

@@ -85,7 +85,7 @@ _git-gtr() {
         _arguments '--editor[Editor to use]:editor:(cursor vscode zed idea pycharm webstorm vim nvim emacs sublime nano atom none)'
         ;;
       ai)
-        _arguments '--ai[AI tool to use]:tool:(aider claude codex cursor continue opencode none)'
+        _arguments '--ai[AI tool to use]:tool:(aider claude codex continue cursor gemini opencode none)'
         ;;
       rm)
         _arguments \