Invalid API key error in Claude Code (Ark Coding Plan) after login

[MK-D-Luffy]

Description

Using Claude Code with Coding Plan API key on Linux: I get "Invalid API key · Please run /login" error even after successful login.

Steps to Reproduce

1. Login to Claude Code with Ark Coding Plan API key (Linux)
2. Confirm login success
3. Run any command requiring API auth
4. Get "Invalid API key · Please run /login" error

Environment

• OS: Linux
• Tool: Claude Code
• API Type: Ark Coding Plan

Additional Context

• API key is correct (no typos/expiry)
• Re-logged multiple times, issue persists