Sessions.Start ignores BrowserbaseSessionCreateParams.Region in remote mode

[moskvinspace]

Environment

stagehand-go v3.21.0, default remote mode.

Repro

client := stagehand.NewClient()
resp, _ := client.Sessions.Start(ctx, stagehand.SessionStartParams{
    ModelName: "openai/gpt-4o-mini",
    Browser:   stagehand.SessionStartParamsBrowser{Type: "browserbase"},
    BrowserbaseSessionCreateParams: stagehand.SessionStartParamsBrowserbaseSessionCreateParams{
        Region: "eu-central-1",
    },
})

Expected

Session created in eu-central-1.

Actual

Session created in us-west-2 (GET /v1/sessions/{id} → "region": "us-west-2").
No error or warning — the Region field has no effect in remote mode.

Workaround

The hosted Stagehand API is regional and the default host serves us-west-2. Pointing the
client at the region-matched host makes the session start in the requested region:

client := stagehand.NewClient(
    option.WithBaseURL("https://api.euc1.stagehand.browserbase.com"), // eu-central-1
)

Region → host: us-east-1 → api.use1.…, eu-central-1 → api.euc1.…,
ap-southeast-1 → api.apse1.stagehand.browserbase.com.