OpenCode

Full deep dive: OpenCode Architecture Breakdown

OpenCode is an open-source (MIT) terminal-first AI coding agent built by the SST team, with 120K+ GitHub stars and 5M monthly users. It features a client/server architecture (Go + Bubble Tea TUI), native LSP error feedback loop, dual agents (Build/Plan), and support for 75+ LLM providers via Models.dev — making it the leading open-source alternative to Claude Code.

Architecture Overview

OpenCode uses a client/server design:

1. Agent Server — runs locally, handles all LLM interactions, file operations, and tool execution
2. TUI Client — Bubble Tea-based terminal UI that communicates with the server
3. LSP Bridge — automatically feeds language server diagnostics back into the agent loop

Key Design Decisions

Decision	Detail
Client/server split	TUI is just one client — architecture supports IDE extensions, web UI, programmatic access
LSP error feedback	Automatic error detection and self-correction — catches type errors, syntax errors without running compiler
Dual agents	Build (read/write) for development, Plan (read-only) for safe analysis
Models.dev integration	75+ providers via community registry — no vendor lock-in
Local-only execution	All code stays on your machine — no cloud execution, privacy by default

Why It's in Trial

OpenCode's LSP integration (the only terminal agent with native LSP error feedback) and its multi-provider model support are genuine architectural differentiators. The client/server design is forward-looking — it decouples the agent runtime from any single interface. For teams evaluating open-source alternatives to Claude Code, OpenCode is the most mature option. See the full deep dive for architecture diagrams and detailed comparisons.

Key Characteristics

Property	Value
Company	SST / opencode-ai (community)
Language	Go (Bubble Tea TUI)
Model support	75+ providers (Models.dev)
Key innovations	LSP error feedback loop, client/server architecture, dual agents
License	MIT (GitHub)
Sources	OpenCode Website, GitHub