@google/gemini-cli-sdk

TypeScript SDK for Google Gemini CLI - spawn and interact with Gemini CLI as a subprocess.

Features

- 🚀 Simple API: Easy-to-use client for Gemini CLI
- 📡 Streaming Support: Real-time event streaming
- 🔧 TypeScript: Full type safety with TypeScript
- 🎯 Tool Calling: Automatic tool execution handling
- 📦 Lightweight: Minimal dependencies
- 🔄 Session Management: Resume previous sessions
- ⚡ Async Generators: Modern async/await patterns

Installation

``bash
npm install @google/gemini-cli-sdk @google/gemini-cli
`

Or with pnpm:

`bash
pnpm add @google/gemini-cli-sdk @google/gemini-cli
`

Prerequisites

- Node.js >= 18.0.0
- @google/gemini-cli installed (peer dependency)
- Google AI API Key

Quick Start

$3

`typescript
import { GeminiClient } from '@google/gemini-cli-sdk';

const client = new GeminiClient({
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
model: 'gemini-2.0-flash-exp',
});

// Get complete response
const result = await client.query('Explain TypeScript generics');
console.log(result.response);
console.log('Tokens used:', result.stats?.total_tokens);
`

$3

`typescript
import { GeminiClient } from '@google/gemini-cli-sdk';

const client = new GeminiClient({
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
});

// Stream events in real-time
for await (const event of client.stream('Write a hello world program')) {
if (event.type === 'message' && event.role === 'assistant' && event.delta) {
process.stdout.write(event.content);
}
}
`

$3

`typescript
import { query } from '@google/gemini-cli-sdk';

const stream = query('Hello, Gemini!', {
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
});

for await (const event of stream) {
console.log(event);
}
`

API Reference

$3

High-level client for interacting with Gemini CLI.

#### Constructor

`typescript
new GeminiClient(options: GeminiOptions)
`

#### Methods

##### query(prompt: string): Promise

Send a query and get the complete result.

`typescript
const result = await client.query('Explain async/await');
console.log(result.response);
console.log(result.stats);
`

##### stream(prompt: string): AsyncGenerator

Stream events from Gemini CLI.

`typescript
for await (const event of client.stream('Hello')) {
if (event.type === 'message') {
console.log(event.content);
}
}
`

##### getStatus(): ProcessStatus

Get current process status.

`typescript
const status = client.getStatus();
// 'idle' | 'running' | 'completed' | 'cancelled' | 'error'
`

##### getSessionId(): string | null

Get current session ID.

`typescript
const sessionId = client.getSessionId();
`

$3

Low-level function to query Gemini CLI.

`typescript
import { query } from '@google/gemini-cli-sdk';

for await (const event of query('Hello', options)) {
console.log(event);
}
`

Configuration Options

`typescript
interface GeminiOptions {
// Required
pathToGeminiCLI: string;

// Optional
apiKey?: string; // Or set GOOGLE_API_KEY env var
model?: string; // Default: 'gemini-2.0-flash-exp'
cwd?: string; // Working directory
approvalMode?: 'default' | 'auto_edit' | 'yolo';
allowedTools?: string[]; // e.g., ['read', 'write', 'bash']
allowedMcpServerNames?: string[];
debug?: boolean;
resumeSessionId?: string; // Resume previous session
sandbox?: boolean;
includeDirectories?: string[];
env?: Record; // Custom env vars
timeout?: number; // Timeout in milliseconds
}
`

Event Types

$3

Session initialization event.

`typescript
{
type: 'init',
timestamp: '2025-12-08T10:30:00.123Z',
session_id: 'abc123',
model: 'gemini-2.0-flash-exp'
}
`

$3

Message content from user or assistant.

`typescript
{
type: 'message',
timestamp: '2025-12-08T10:30:01.000Z',
role: 'assistant',
content: 'Hello! How can I help you?',
delta: true // Incremental content
}
`

$3

Tool call request.

`typescript
{
type: 'tool_use',
timestamp: '2025-12-08T10:30:02.000Z',
tool_name: 'read',
tool_id: 'tool_123',
parameters: { path: 'package.json' }
}
`

$3

Tool execution result.

`typescript
{
type: 'tool_result',
timestamp: '2025-12-08T10:30:03.000Z',
tool_id: 'tool_123',
status: 'success',
output: '{"name": "my-app"}'
}
`

$3

Error or warning event.

`typescript
{
type: 'error',
timestamp: '2025-12-08T10:30:04.000Z',
severity: 'warning',
message: 'Loop detected'
}
`

$3

Final result with statistics.

`typescript
{
type: 'result',
timestamp: '2025-12-08T10:30:05.000Z',
status: 'success',
stats: {
total_tokens: 1500,
input_tokens: 500,
output_tokens: 1000,
duration_ms: 5000,
tool_calls: 3
}
}
`

Advanced Examples

$3

`typescript
const client = new GeminiClient({
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
approvalMode: 'auto_edit', // Auto-approve edit tools
allowedTools: ['read', 'write'], // Allow these tools without confirmation
});

const result = await client.query('Read package.json and update version');
`

$3

`typescript
const client = new GeminiClient({
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
resumeSessionId: 'latest', // Or specific session ID
});

const result = await client.query('Continue from where we left off');
`

$3

`typescript
const client = new GeminiClient(options);

client.on('event', (event) => {
console.log('Event:', event.type);
});

client.on('status', (status) => {
console.log('Status:', status);
});

client.on('session', (sessionId) => {
console.log('Session ID:', sessionId);
});

client.on('error', (error) => {
console.error('Error:', error);
});

await client.query('Hello');
`

$3

`typescript
const client = new GeminiClient({
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
cwd: '/path/to/project',
includeDirectories: ['./src', './docs'],
});
`

$3

`typescript
const client = new GeminiClient({
pathToGeminiCLI: './node_modules/@google/gemini-cli/bundle/gemini.js',
apiKey: process.env.GOOGLE_API_KEY,
timeout: 30000, // 30 seconds
});

try {
const result = await client.query('Long running task');
} catch (error) {
if (error.code === 130) {
console.log('Query timed out');
}
}
`

Utilities

$3

Automatically find Gemini CLI executable.

`typescript
import { findGeminiCLI } from '@google/gemini-cli-sdk';

const cliPath = findGeminiCLI();
console.log('Found Gemini CLI at:', cliPath);
`

$3

Get API key from options or environment.

`typescript
import { getApiKey } from '@google/gemini-cli-sdk';

const apiKey = getApiKey(); // Reads from GOOGLE_API_KEY env var
`

$3

Format duration in milliseconds.

`typescript
import { formatDuration } from '@google/gemini-cli-sdk';

console.log(formatDuration(5432)); // "5.43s"
console.log(formatDuration(125000)); // "2m 5s"
`

$3

Format token count with commas.

`typescript
import { formatTokens } from '@google/gemini-cli-sdk';

console.log(formatTokens(1234567)); // "1,234,567"
`

Error Handling

`typescript
import { GeminiSDKError, ExitCode } from '@google/gemini-cli-sdk';

try {
const result = await client.query('Hello');
} catch (error) {
if (error instanceof GeminiSDKError) {
console.error('SDK Error:', error.message);
console.error('Exit Code:', error.code);
console.error('Details:', error.details);

if (error.code === ExitCode.USER_INTERRUPTED) {
console.log('User cancelled the query');
}
}
}
`

Environment Variables

- GOOGLE_API_KEY: Google AI API Key (required if not provided in options)
- GEMINI_CLI_PATH: Custom path to Gemini CLI executable
- DEBUG: Enable debug logging

Architecture

This SDK follows the same architecture as @anthropic-ai/claude-agent-sdk:

1. Subprocess Spawning: Gemini CLI runs as a separate Node.js process
2. stdio Communication: JSON-Lines format over stdin/stdout
3. Event Streaming: Real-time event streaming via AsyncGenerator
4. Process Isolation: Clean separation between SDK and CLI

Comparison with Claude Code SDK

| Feature | Gemini CLI SDK | Claude Code SDK |
|---------|---------------|-----------------|
| Output Format | --output-format stream-json | JSON-Lines |
| Tool Calling | CLI handles automatically | SDK handles |
| Session Management | CLI built-in | SDK manages |
| Approval Mode | --approval-mode flag | SDK config |
| API Key | GOOGLE_API_KEY | ANTHROPIC_API_KEY |

Development

`bash


Install dependencies

pnpm install

Build

pnpm build

Watch mode

pnpm dev

Run tests

pnpm test

Lint

pnpm lint

Format

pnpm format
``

License

MIT

Contributing

Contributions are welcome! Please open an issue or submit a pull request.

Related Projects

- @google/gemini-cli - Official Gemini CLI
- @anthropic-ai/claude-agent-sdk - Claude Agent SDK (inspiration)

Support

For issues and questions:
- GitHub Issues: github.com/yourusername/gemini-cli-sdk/issues
- Gemini CLI Docs: github.com/google-gemini/gemini-cli