Before signing in, merge this server entry into ~/.config/opencode/opencode.json (or your XDG config directory), preserving other settings. A fixed callback port avoids re-login redirect mismatches observed with OpenCode 2.0.29 and Keycloak:
Open OpenCode, run /mcps, select ArcMeld, and sign in. Confirm it shows connected. Local stdio servers do not use OAuth.
Keycloak says "Invalid parameter: redirect_uri"?
After pinning the callback port, clear only ArcMeld's saved credentials and client registration:
opencode mcp logout ArcMeld
Close the old error tab and start a fresh sign-in from /mcps. Do not refresh the old login URL. Port 19876 must be free; use another fixed port if needed.
Install the native OpenCode skill separately from MCP authentication:
curl -fsSL 'https://arcmeld.com/opencode-skill' | sh
Installs SKILL.md to ${XDG_CONFIG_HOME:-~/.config}/opencode/skills/arcmeld/. Mention @arcmeld to load it. MCP prompts are reference material, not an installed skill.
3 Quick Start
Open a Figma file, run the ArcMeld plugin, and sign in to Remote mode with the same account as your AI tool
Ask your AI tool: List open Figma documents
Choose a file, then describe what you want to inspect or design
Keep the plugin open in each file you want to access. The agent uses connect without a channel to discover files, then connects to each channel and reads doc_info for document names.