feat: add Gemini run mode

src/utils/gemini-cli-resolver.ts

@@ -0,0 +1,67 @@
+/**
+ * @fileoverview Resolve the Gemini CLI binary across common install paths.
+ *
+ * Mirrors codex-cli-resolver.ts and opencode-cli-resolver.ts. Finds the
+ * `gemini` binary and provides an augmented PATH directory for tmux sessions.
+ *
+ * @module utils/gemini-cli-resolver
+ */
+
+import { execSync } from 'node:child_process';
+import { existsSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { homedir } from 'node:os';
+import { EXEC_TIMEOUT_MS } from '../config/exec-timeout.js';
+
+/** Common directories where the Gemini CLI binary may be installed */
+const GEMINI_SEARCH_DIRS = [
+  join(homedir(), '.gemini', 'bin'),
+  join(homedir(), '.local', 'bin'),
+  '/usr/local/bin',
+  join(homedir(), '.bun', 'bin'),
+  join(homedir(), '.npm-global', 'bin'),
+  join(homedir(), 'bin'),
+];
+
+/** Cached directory containing the gemini binary (empty string = searched but not found) */
+let _geminiDir: string | null = null;
+
+/**
+ * Finds the directory containing the `gemini` binary.
+ * Checks `which gemini` first, then falls back to common install locations.
+ *
+ * @returns Directory path, or null if not found
+ */
+export function resolveGeminiDir(): string | null {
+  if (_geminiDir !== null) return _geminiDir || null;
+
+  try {
+    const result = execSync('which gemini', {
+      encoding: 'utf-8',
+      timeout: EXEC_TIMEOUT_MS,
+    }).trim();
+    if (result && existsSync(result)) {
+      _geminiDir = dirname(result);
+      return _geminiDir;
+    }
+  } catch {
+    // Gemini not in PATH, will check common locations
+  }
+
+  for (const dir of GEMINI_SEARCH_DIRS) {
+    if (existsSync(join(dir, 'gemini'))) {
+      _geminiDir = dir;
+      return _geminiDir;
+    }
+  }
+
+  _geminiDir = '';
+  return null;
+}
+
+/**
+ * Check if Gemini CLI is available on the system.
+ */
+export function isGeminiAvailable(): boolean {
+  return resolveGeminiDir() !== null;
+}

src/utils/index.ts

@@ -29,3 +29,4 @@ export { wrapWithNice } from './nice-wrapper.js';
 export { findClaudeDir, getAugmentedPath } from './claude-cli-resolver.js';
 export { resolveOpenCodeDir } from './opencode-cli-resolver.js';
 export { resolveCodexDir, isCodexAvailable } from './codex-cli-resolver.js';
+export { resolveGeminiDir } from './gemini-cli-resolver.js';