Mcp Auto Reauth

An OpenCode plugin that refreshes expired MCP OAuth tokens at startup when a refresh token is available.

Why

Remote MCP servers that use OAuth can leave OpenCode with an expired access token. This plugin performs a safe startup refresh pass so OpenCode can reconnect without manually re-running authentication.

The plugin intentionally does not run opencode mcp auth <server> from inside OpenCode. Starting the OpenCode CLI while plugins are loading can recursively load the same plugin and crash the process. If a server has no refresh token or no stored OAuth client information, the plugin logs that manual authentication is required instead.

How it works

1. Reads mcp-auth.json from the OpenCode data directory.
2. Checks each stored MCP OAuth entry:
   • Token still valid — skips.
   • No expiry — skips, matching OpenCode's behavior.
   • Expired token with refreshToken and clientInfo.clientId — refreshes directly via OAuth metadata discovery.
   • Incomplete OAuth entry with a stored serverUrl but no access token — asks OpenCode's in-process MCP auth API to run the interactive browser flow.
   • Missing token, refresh token, client id, or server URL — logs that manual authentication is required.
3. Discovers the token endpoint using standard OAuth protected-resource / authorization-server metadata.
4. Writes refreshed tokens back to mcp-auth.json atomically with 0600 permissions where supported.

A 60-second buffer is applied before expiry to avoid racing with startup.

Install

Add it to your OpenCode config (opencode.json or opencode.jsonc):

{
  "plugin": [
    "@mathew-cf/opencode-mcp-auto-reauth"
  ]
}

Manual auth fallback

Some OAuth servers do not issue refresh tokens, and some missing-token states do not include enough server metadata for the plugin to start OpenCode's in-process browser flow. For those, run OpenCode's normal authentication command outside of plugin startup:

opencode mcp auth <server-name>

Disable temporarily

Set this environment variable before starting OpenCode:

OPENCODE_MCP_AUTO_REAUTH=0 opencode

Platform support

Platform	Data directory
Linux	$XDG_DATA_HOME/opencode or ~/.local/share/opencode
macOS	$XDG_DATA_HOME/opencode or ~/.local/share/opencode
Windows	%LOCALAPPDATA%\\opencode or ~/AppData/Local/opencode

The plugin also reads OpenCode config from the current project (opencode.json(c) and .opencode/opencode.json(c)) plus the global config directory to find a remote server URL if the auth entry does not already include serverUrl.

Known issue: stale /mcps status

After the plugin completes interactive auth, it connects the MCP server in the current OpenCode backend session and shows a success toast. The /mcps dialog can still show stale needs_auth / Disabled status until the TUI refreshes its MCP sync state.

This is a display issue: the tools can be available even while the dialog is stale. Pressing space on the stale row, reopening/restarting OpenCode, or any future OpenCode-side MCP status refresh event will update the dialog.

Logs

Activity is logged to mcp-auto-reauth.log in the same data directory:

2026-05-27T14:30:01.000Z [mcp-auto-reauth] checking 3 server(s)
2026-05-27T14:30:01.001Z [mcp-auto-reauth] my-server: skip — token still valid or has no expiry
2026-05-27T14:30:01.002Z [mcp-auto-reauth] other-server: refreshing expired OAuth token
2026-05-27T14:30:02.500Z [mcp-auto-reauth] other-server: refreshed successfully
2026-05-27T14:30:02.501Z [mcp-auto-reauth] done (auth file updated)

Logs include server names and status messages only. Tokens and client secrets are never logged.

Development

bun install
bun run build
bun run typecheck

License

Apache-2.0