[Bug]: Grok chat shows Claude could not finish the response

[iuri1911]

What happened?

Using the installed Grok CLI as the chat model shows Claude could not finish the response. The turn never reached Claude. Grok failed, and Tinycast reported Claude's missing-result fallback.

Expected: the Grok CLI's own error, and a signed-out CLI shown as sign-in required rather than ready.

Steps to reproduce

1. Install Grok CLI 1.0.40 (~/.grok/bin/grok) and leave it signed out. grok models still exits 0 and prints the catalog under You are not authenticated.
2. In Tinycast, enable Grok. Discovery treats that catalog as a login, so the model is offered.
3. Send a chat message on the Grok route.
4. The CLI prints an error result and exits 1:

{"type":"result","subtype":"error_during_execution","is_error":true,"errors":["Not signed in. …"],"session_id":""}

There is no result string. InstalledAIStreamDecoder reuses the Claude decoder, which falls back to Claude could not finish the response.

The same fallback fires for any Grok execution error that puts the cause in errors and omits result (error_during_execution, error_max_turns, error_max_structured_output_retries).

Environment

• Tinycast: current main (9c4755f)
• macOS 26.7 (25G229), Intel x86_64
• Grok CLI 1.0.40 (eb1a2256660d)
• Claude CLI is not installed on this machine, which makes the Claude sentence obviously wrong

Fix

Already written, waiting on approved: #1043

• Read errors (then result) and name Grok if both are empty.
• Ignore an empty session_id.
• Treat the signed-out banner on grok models as sign-in required. The catalog is still parsed; it is not offered until the CLI is signed in.

I'm willing to implement this myself once this issue is labelled approved. The patch is the PR above.

[github-actions]

Thanks for opening this.

A few things worth knowing up front:

Tinycast aims to stay small and focused, so it is extremely selective about new
features. Every request is read, and the ideas that truly matter are the ones taken on.
Smaller conveniences are usually closed.

Warning

Don't write code for this yet. This issue has to be labelled approved first.

1. Wait for a maintainer to add the approved label. That label is the only green light —
   a reply, a reaction or silence is not one.
2. Once it's there, open your pull request with Closes #1044 in the description.
3. A pull request whose linked issue isn't approved is closed automatically, unreviewed.

Docs-only changes (*.md, docs/, website/) skip this and need no approval.

Thanks for opening this! A maintainer will take a look soon.