# OpenCode Features and Practical Usage 🤖 Turn OpenCode from "a tool you chat with in the terminal" into "a dev server you drive from code." The SDK plus a headless server let you embed AI coding into CI and custom UIs. 🏷️ Title: Type-safe JS client and headless server 🔗 URL: 📘 Overview OpenCode can run not only as a TUI but as a headless server you control over HTTP. The type-safe `@opencode-ai/sdk` JavaScript/TypeScript client connects to that server to create sessions, send prompts, and subscribe to events. All types are generated from the server's OpenAPI spec, so completion and type-checking work out of the box. ⚙️ How It Works ・Start the server: `opencode serve` launches a headless server, defaulting to `127.0.0.1:4096`. The SDK's `createOpencode()` can both start the server and hand you a client in one call. ・Connect a client: For an existing server, use `createOpencodeClient({ baseUrl: "http://localhost:4096" })`. ・Core APIs: Create/list/get/update/delete sessions, share/unshare, abort, and revert/unrevert messages. Send prompts with `client.session.prompt()`. ・Structured output: Pass `format: { type: "json_schema", schema: {...} }` to receive validated JSON matching your schema, ideal for downstream machine processing. ・Event stream: `client.event.subscribe()` gives you server-sent events as a stream to monitor long-running operations. 🛠️ Practical Usage Starting the server from code is a few calls: `createOpencode()` returns both a `client` and `server`, then `client.session.create()` opens a session and `client.session.prompt()` sends a prompt (passing a `format` of `json_schema` for structured output), and `server.close()` shuts it down. For CI, `noReply: true` is handy when you want to inject context without triggering an AI response. 💡 Use Cases ・A review bot fetches a structured findings JSON via the SDK (instead of `opencode run`) and posts a formatted GitHub PR comment. ・A custom web UI or editor extension uses the `tui` APIs to append/submit prompts and show toasts, building a bespoke frontend. ・A nightly batch sends the same analysis prompt across many repos and stores the resulting JSON in a data platform. ⚠️ Caveats ・SDK config overrides and merges with `opencode.json` rather than replacing it entirely, so watch for lingering unintended settings. ・Structured output retries on validation failure (default 2). If it still fails, ` holds a `StructuredOutputError`. Keep schemas small and focused for reliability. ・Calls like `client.session.get()` throw on an invalid ID, so wrap them in try-catch. #OpenCode# #AIAgents#