OpenCode 2.0 ships: one background service for TUI, web and desktop, Code Mode for all MCP servers, background subagents, and @opencode/sdk

OpenCode 2.0, the open-source coding agent from Anomaly (anomalyco/opencode), is a major overhaul. A single local background service now runs automatically and is shared by the terminal UI, web interface, desktop app and scripts built on the new @opencode/client package; opencode pair exposes it to other hosts. The server API was rewritten from scratch, and OpenCode can call its own API, for example to move a session into a git worktree. The new @opencode/codemode package is a minimal JavaScript interpreter that turns MCP servers and OpenAPI endpoints into functions, so the model can call a tool, map over results and call another in one round trip; all MCP servers default to Code Mode, which the team says lets you add many servers with minimal context bloat. Background subagents and background shell commands let the primary agent keep working while long tasks run, and Ctrl+B moves foreground work to the background. More than 80 features are now internal plugins, TUI plugins are stable, and everything is hot-reloadable. @opencode/sdk exposes the same engine as a library. The launch note publishes no benchmarks. Breaking changes: V1 plugins do not run, the server API is different, and tui.json moves to cli.json. Upgrade from the latest 1.x with opencode upgrade --major.