Expired enterprise auth token makes opencode unrecoverable (cryptic decode error + can't re-login) #31649

Description

We host our enterprise config behind Cloudflare Access, discovered via the wellknown
auth type (<origin>/.well-known/opencode → remote_config). When the stored token
expires, opencode gets stuck and can't recover on its own:

• Access answers the unauthenticated request with its HTML login page and HTTP 200.
  opencode's remote-config fetch accepts the 200, then fails to JSON-decode the HTML and
  dies, so startup aborts with failed to decode remote config ... Decode error (200)
  and a raw stack trace.
• opencode auth login <url> can't fix it either: it bootstraps the project first, which
  loads that same remote config with the expired token and crashes before the login flow
  runs. The only workaround is rm ~/.local/share/opencode/auth.json, then re-login.

Seen since ~1.14.40 (when enterprise config moved behind Access)

Plugins

No response

OpenCode version

1.16.2

Steps to reproduce

1. opencode auth login <enterprise-url> to set up wellknown auth.
2. Let the token expire (or put an invalid token in auth.json).
3. Run opencode → fatal Decode error (200) with a stack trace.
4. Run opencode auth login <enterprise-url> to recover → it also crashes; you have to
   delete auth.json first.

Screenshot and/or share link

No response

Operating System

macOS

Terminal

Ghostty