Add Gemini CLI support

js/src/tools/gemini.mjs

@@ -0,0 +1,317 @@
+/**
+ * Gemini CLI tool configuration
+ * Based on Google's official gemini-cli: https://github.com/google-gemini/gemini-cli
+ */
+
+/**
+ * Available Gemini model configurations
+ * Maps aliases to full model IDs
+ */
+export const modelMap = {
+  // Gemini 2.5 models (current stable)
+  flash: 'gemini-2.5-flash',
+  '2.5-flash': 'gemini-2.5-flash',
+  pro: 'gemini-2.5-pro',
+  '2.5-pro': 'gemini-2.5-pro',
+  lite: 'gemini-2.5-flash-lite',
+  '2.5-lite': 'gemini-2.5-flash-lite',
+  // Gemini 3 models (latest generation)
+  '3-flash': 'gemini-3-flash-preview',
+  '3-pro': 'gemini-3-pro-preview',
+  // Legacy aliases
+  'gemini-flash': 'gemini-2.5-flash',
+  'gemini-pro': 'gemini-2.5-pro',
+};
+
+/**
+ * Map model alias to full model ID
+ * @param {Object} options - Options
+ * @param {string} options.model - Model alias or full ID
+ * @returns {string} Full model ID
+ */
+export function mapModelToId(options) {
+  const { model } = options;
+  return modelMap[model] || model;
+}
+
+/**
+ * Build command line arguments for Gemini CLI
+ * @param {Object} options - Options
+ * @param {string} [options.prompt] - User prompt (for non-interactive mode)
+ * @param {string} [options.systemPrompt] - System prompt (combined with user prompt)
+ * @param {string} [options.model] - Model to use
+ * @param {boolean} [options.json] - JSON output mode (stream-json format)
+ * @param {boolean} [options.yolo] - Auto-approve all tool calls (autonomous mode)
+ * @param {boolean} [options.sandbox] - Run tools in secure sandbox
+ * @param {boolean} [options.debug] - Enable debug output
+ * @param {boolean} [options.checkpointing] - Save project snapshot before file modifications
+ * @param {boolean} [options.interactive] - Start interactive session with initial prompt
+ * @returns {string[]} Array of CLI arguments
+ */
+export function buildArgs(options) {
+  const {
+    prompt,
+    model,
+    json = false,
+    yolo = true, // Enable autonomous mode by default for agent use
+    sandbox = false,
+    debug = false,
+    checkpointing = false,
+    interactive = false,
+  } = options;
+
+  const args = [];
+
+  if (model) {
+    const mappedModel = mapModelToId({ model });
+    args.push('-m', mappedModel);
+  }
+
+  // Enable yolo mode for autonomous execution (auto-approve all tool calls)
+  if (yolo) {
+    args.push('--yolo');
+  }
+
+  // Sandbox mode for secure execution
+  if (sandbox) {
+    args.push('--sandbox');
+  }
+
+  // Debug output
+  if (debug) {
+    args.push('-d');
+  }
+
+  // Checkpointing for file modifications
+  if (checkpointing) {
+    args.push('--checkpointing');
+  }
+
+  // JSON output mode - use stream-json for streaming events
+  if (json) {
+    args.push('--output-format', 'stream-json');
+  }
+
+  // Add prompt for non-interactive mode
+  if (prompt) {
+    if (interactive) {
+      args.push('-i', prompt);
+    } else {
+      args.push('-p', prompt);
+    }
+  }
+
+  return args;
+}
+
+/**
+ * Build complete command string for Gemini CLI
+ * @param {Object} options - Options
+ * @param {string} options.workingDirectory - Working directory
+ * @param {string} [options.prompt] - User prompt
+ * @param {string} [options.systemPrompt] - System prompt
+ * @param {string} [options.model] - Model to use
+ * @param {boolean} [options.json] - JSON output mode
+ * @param {boolean} [options.yolo] - Auto-approve all tool calls
+ * @param {boolean} [options.sandbox] - Run tools in secure sandbox
+ * @param {boolean} [options.debug] - Enable debug output
+ * @param {boolean} [options.checkpointing] - Save project snapshot
+ * @param {boolean} [options.interactive] - Start interactive session
+ * @returns {string} Complete command string
+ */
+export function buildCommand(options) {
+  // eslint-disable-next-line no-unused-vars
+  const { workingDirectory, systemPrompt, prompt, ...argOptions } = options;
+
+  // Gemini CLI supports system prompt via GEMINI_SYSTEM_PROMPT env var
+  // or via .gemini/system.md file. For now, combine with user prompt.
+  const combinedPrompt = systemPrompt
+    ? `${systemPrompt}\n\n${prompt || ''}`
+    : prompt || '';
+
+  const args = buildArgs({ ...argOptions, prompt: combinedPrompt });
+  return `gemini ${args.map(escapeArg).join(' ')}`.trim();
+}
+
+/**
+ * Escape an argument for shell usage
+ * @param {string} arg - Argument to escape
+ * @returns {string} Escaped argument
+ */
+function escapeArg(arg) {
+  // If argument contains spaces, quotes, or special chars, wrap in quotes
+  if (/["\s$`\\]/.test(arg)) {
+    return `"${arg.replace(/"/g, '\\"').replace(/\$/g, '\\$').replace(/`/g, '\\`').replace(/\\/g, '\\\\')}"`;
+  }
+  return arg;
+}
+
+/**
+ * Parse JSON messages from Gemini CLI output
+ * Gemini CLI outputs NDJSON (newline-delimited JSON) in stream-json mode
+ * @param {Object} options - Options
+ * @param {string} options.output - Raw output string
+ * @returns {Object[]} Array of parsed JSON messages
+ */
+export function parseOutput(options) {
+  const { output } = options;
+  const messages = [];
+  const lines = output.split('\n');
+
+  for (const line of lines) {
+    const trimmed = line.trim();
+    if (!trimmed || !trimmed.startsWith('{')) {
+      continue;
+    }
+
+    try {
+      const parsed = JSON.parse(trimmed);
+      messages.push(parsed);
+    } catch {
+      // Skip lines that aren't valid JSON
+    }
+  }
+
+  return messages;
+}
+
+/**
+ * Extract session ID from Gemini CLI output
+ * Gemini CLI may include session information in its output
+ * @param {Object} options - Options
+ * @param {string} options.output - Raw output string
+ * @returns {string|null} Session ID or null
+ */
+export function extractSessionId(options) {
+  const { output } = options;
+  const messages = parseOutput({ output });
+
+  for (const msg of messages) {
+    if (msg.session_id) {
+      return msg.session_id;
+    }
+    // Gemini might use different session identifier
+    if (msg.conversation_id) {
+      return msg.conversation_id;
+    }
+  }
+
+  return null;
+}
+
+/**
+ * Extract usage statistics from Gemini CLI output
+ * @param {Object} options - Options
+ * @param {string} options.output - Raw output string
+ * @returns {Object} Usage statistics
+ */
+export function extractUsage(options) {
+  const { output } = options;
+  const messages = parseOutput({ output });
+
+  const usage = {
+    inputTokens: 0,
+    outputTokens: 0,
+    totalTokens: 0,
+  };
+
+  for (const msg of messages) {
+    // Check for usage metadata in different possible formats
+    if (msg.usage) {
+      const u = msg.usage;
+      if (u.input_tokens !== undefined) {
+        usage.inputTokens += u.input_tokens;
+      }
+      if (u.output_tokens !== undefined) {
+        usage.outputTokens += u.output_tokens;
+      }
+      if (u.total_tokens !== undefined) {
+        usage.totalTokens += u.total_tokens;
+      }
+      // Also check camelCase variants
+      if (u.inputTokens !== undefined) {
+        usage.inputTokens += u.inputTokens;
+      }
+      if (u.outputTokens !== undefined) {
+        usage.outputTokens += u.outputTokens;
+      }
+      if (u.totalTokens !== undefined) {
+        usage.totalTokens += u.totalTokens;
+      }
+    }
+
+    // Also check for Gemini-specific token metrics
+    if (msg.usageMetadata) {
+      const u = msg.usageMetadata;
+      if (u.promptTokenCount !== undefined) {
+        usage.inputTokens += u.promptTokenCount;
+      }
+      if (u.candidatesTokenCount !== undefined) {
+        usage.outputTokens += u.candidatesTokenCount;
+      }
+      if (u.totalTokenCount !== undefined) {
+        usage.totalTokens += u.totalTokenCount;
+      }
+    }
+  }
+
+  // Calculate total if not provided
+  if (
+    usage.totalTokens === 0 &&
+    (usage.inputTokens > 0 || usage.outputTokens > 0)
+  ) {
+    usage.totalTokens = usage.inputTokens + usage.outputTokens;
+  }
+
+  return usage;
+}
+
+/**
+ * Detect errors in Gemini CLI output
+ * @param {Object} options - Options
+ * @param {string} options.output - Raw output string
+ * @returns {Object} Error detection result
+ */
+export function detectErrors(options) {
+  const { output } = options;
+  const messages = parseOutput({ output });
+
+  for (const msg of messages) {
+    // Check for explicit error message types
+    if (msg.type === 'error' || msg.error) {
+      return {
+        hasError: true,
+        errorType: msg.type || 'error',
+        message: msg.message || msg.error || 'Unknown error',
+      };
+    }
+  }
+
+  return { hasError: false };
+}
+
+/**
+ * Gemini CLI tool configuration
+ */
+export const geminiTool = {
+  name: 'gemini',
+  displayName: 'Gemini CLI',
+  executable: 'gemini',
+  supportsJsonOutput: true,
+  supportsJsonInput: false, // Gemini CLI uses -p flag for prompts, not stdin JSON
+  supportsSystemPrompt: false, // System prompt via env var or file, combined with user prompt
+  supportsResume: true, // Via /chat resume command in interactive mode
+  supportsYolo: true, // Supports --yolo for autonomous execution
+  supportsSandbox: true, // Supports --sandbox for secure execution
+  supportsCheckpointing: true, // Supports --checkpointing
+  supportsDebug: true, // Supports -d for debug output
+  defaultModel: 'gemini-2.5-flash',
+  modelMap,
+  mapModelToId,
+  buildArgs,
+  buildCommand,
+  parseOutput,
+  extractSessionId,
+  extractUsage,
+  detectErrors,
+};

js/src/tools/index.mjs

@@ -1,12 +1,13 @@
 /**
  * Tool configurations and utilities
- * Provides configuration for different CLI agents: claude, codex, opencode, agent
+ * Provides configuration for different CLI agents: claude, codex, opencode, agent, gemini
  */
 
 import { claudeTool } from './claude.mjs';
 import { codexTool } from './codex.mjs';
 import { opencodeTool } from './opencode.mjs';
 import { agentTool } from './agent.mjs';
+import { geminiTool } from './gemini.mjs';
 
 /**
  * Available tool configurations
@@ -16,6 +17,7 @@ export const tools = {
   codex: codexTool,
   opencode: opencodeTool,
   agent: agentTool,
+  gemini: geminiTool,
 };
 
 /**
@@ -54,4 +56,4 @@ export function isToolSupported(options) {
   return toolName in tools;
 }
 
-export { claudeTool, codexTool, opencodeTool, agentTool };
+export { claudeTool, codexTool, opencodeTool, agentTool, geminiTool };