Web lookup failures now stop with actionable errors

What changed

Web lookup failures caused by permanent configuration problems now stop the assistant's tool loop immediately instead of being retried. If an assistant reaches its configured tool-call step limit while still requesting tools, the turn now ends with an explicit error instead of an empty successful response.

Why this matters to the user

Users may now see an actionable Web Search or network error earlier in a turn. Missing API keys, missing API hosts, and invalid API hosts are reported separately, while long-running tool loops report that their configured limit was reached rather than appearing to finish without an answer.

What the user should do

Follow the error guidance to configure a compatible Web Search provider, add any required API key, enter a valid HTTP(S) API host, or check the network connection and try again. Valid localhost HTTP endpoints remain supported. For legitimate long-running tasks, increase the assistant's tool-call limit or reduce the task scope.

Notes for release manager

The SSRF guard remains unchanged; Clash Fake-IP addresses are still rejected.