DeepSeek TUI Docs Add Nix and Auth Diagnostics

What changed upstream

The newest official README and install docs now close several gaps that older setup posts still leave fuzzy:

• Credential-source diagnosis is now documented: the README now tells users to run deepseek auth status to see whether the active key is coming from saved config, keyring, or DEEPSEEK_API_KEY.
• Credential cleanup is explicit: the same README now documents deepseek auth clear --provider deepseek as the supported way to remove or rotate a saved key.
• Credential precedence is clearer: upstream now says saved config keys take precedence over keyring and environment variables, which matters when a machine keeps using the wrong DeepSeek account.
• Nix is now a documented install path: the official install docs now include nix run github:Hmbown/DeepSeek-TUI plus flake examples, so Nix and NixOS users no longer need to rely on an inferred community-only path.
• Auto-mode billing is easier to explain correctly: the README now says the route that actually ran is what cost tracking is charged against, even though auto mode begins with a small Flash routing call.

Practical setup guidance

This is not just documentation polish. It changes what a technically trustworthy DeepSeek TUI setup guide should tell readers:

1. Wrong-key debugging should start with a documented source check, not guesswork.
2. Teams rotating credentials need an official cleanup command, not just shell-export advice.
3. Nix users now have a first-party install surface worth indexing directly.
4. Auto mode can be recommended more confidently when cost attribution is tied to the real routed model.

Sources

• DeepSeek TUI GitHub repository README
• DeepSeek TUI install docs
• DeepSeek TUI runtime API docs
• DeepSeek official Claude Code integration guide
• DeepSeek API quick-start
• DeepSeek V4 Flash model card