Run diagnostics

Collect the smallest evidence set that identifies the failing layer. Never print credentials or raw context files.

The shell cannot find xcsh

Run command -v xcsh and xcsh --version. If the path belongs to an old installation channel, remove that channel and reinstall once through the intended channel.

A model is unavailable or authentication fails

Run xcsh --list-models <PROVIDER>. If no models appear, verify the relevant credential is present without echoing it. Retry with a provider-qualified --model name.

For Fable, credits_required means the authenticated Anthropic account is not entitled or funded for that model; xcsh reports it once without retrying. Check Claude subscription access or API billing for the credential in use. An obsolete-client error also does not retry: upgrade xcsh so its Claude Code compatibility header matches the current client, then try again.

A context or resource command fails

Confirm /context status and the explicit namespace. Run validate to separate local manifest errors from live application programming interface (API) errors, then retry a read-only get or diff.

A tool or extension fails during startup

Start from the smallest surface, then widen it:

1. Run with --no-mcp --no-extensions --no-rules, adding --no-pty if the terminal itself is suspect.
2. Re-enable one subsystem, then repeat the failing command.
3. Check optional dependencies with xcsh setup <COMPONENT> --check --json.
4. Check plugins with xcsh plugin doctor.