Originally posted by @aaronball85 in #12798 (reply in thread)

My positron version just updated and the functionality to use a Databricks hosted model as the provider for Positron Assistant as a custom provider doesn't appear to work anymore. The update cleared out my previously entered (and working) custom provider settings.

My About Positron info:
Positron Version: 2026.05.0 build 179
Code - OSS Version: 1.109.2
Commit: b271b10
Date: 2026-04-30T08:01:04.186Z
Electron: 39.3.0
Chromium: 142.0.7444.265
Node.js: 22.21.1
V8: 14.2.231.22-electron.0
OS: Darwin arm64 25.4.0

I have these lines in my settings.json file:

"positron.assistant.provider.customProvider.enable": true,
    "positron.assistant.models.overrides.customProvider": [
        {
            "name": "Databricks Claude Sonnet 4.6",
            "identifier": "databricks-claude-sonnet-4-6"
        }
    ]

When I attempt to re-establish my custom provider connection and enter my PAT and the Base URL of the format https://adb-my_instance_id.azuredatabricks.net/serving-endpoints into the Custom Provider UI, I'm getting a 'Custom Provider endpoint not found. Check your base URL.' error message.

When I attempt to use a modified Base URL https://adb-my_instance_id.azuredatabricks.net/serving-endpoints/anthropic the authentication succeeds, I'll get this error message in the bottom right of the Positron UI after closing out of the Configure Model Providers screen.

If I try to use the modified Base URL https://adb-my_instance_id.azuredatabricks.net/serving-endpoints/anthropic without the positron.assistant.models.overrides.customProvider specification included in the settings.json file, I get this error:

Any suggestions on a fix or resolution?

Another comment from #8612 (comment):

the base url that used to work with previous Positron versions was https://adb-my_instance_id.azuredatabricks.net/serving-endpoints but this no longer appears to work with the Positron 2026.05.0-95 (See discussion here: #12798).

Can Positron be configured to work with both/either endpoints? The Databricks AI Gateway based endpoint and related functionality is still in beta whereas the other is GA.

I think the issue is that with the move to the auth extension, we have this connection check that poses an issue for Databricks when used with the model routing endpoint (serving-endpoints) and we don't provide a model with the request here:

We could check for model overrides for custom provider, and use a model from the overrides in this check. This means the auth extension will need to know about and care about the custom provider overrides though. Other solutions could be to soft fail the connection check, but involves a bunch more clicking if the url/creds were wrong and the user needs to return to the modal again.