Claude Auth

TL;DR

Claude Auth (community plugin by @griffinmartin) is a self-contained Anthropic auth provider for OpenCode that uses your existing Claude Code credentials — no separate login or API key. It reads OAuth tokens from the macOS Keychain (or ~/.claude/.credentials.json elsewhere), caches them with a 30-second TTL, refreshes near-expiry tokens via the Anthropic OAuth endpoint, and re-syncs in the background every 5 minutes. Add opencode-claude-auth@latest to the plugin array. Prerequisite: Claude Code installed and authenticated.

Claude Auth registers its own Anthropic auth provider with a custom fetch handler that intercepts all Anthropic API requests, using your Claude Code credentials.

Key features

Feature	Description
No separate API key	Reuses OAuth tokens from your Claude Code installation
Keychain-first	Reads from macOS Keychain; falls back to ~/.claude/.credentials.json ($CLAUDE_CONFIG_DIR respected) on other platforms
30-second TTL cache	Tokens cached in memory; near-expiry tokens refresh via the Anthropic OAuth endpoint (zero LLM tokens consumed)
Multi-account (macOS)	Multiple Claude Code accounts detected automatically; switch via opencode auth login
auth.json fallback	Syncs credentials to OpenCode auth.json; on Windows writes both known locations
Background re-sync	Every 5 minutes; falls back to the Claude CLI if direct refresh fails

Prerequisites

• Claude Code installed and authenticated (run claude at least once)
• OpenCode installed
• macOS preferred (Keychain); Linux and Windows work via the credentials file fallback

Installation

Add the plugin to ~/.config/opencode/opencode.json:

{
  "plugin": ["opencode-claude-auth@latest"]
}