Route Browserbase session traffic through built-in managed proxies with country, state or city geolocation targeting

Documented steps

1. Authenticate with header X-BB-API-Key: <api-key> on POST https://api.browserbase.com/v1/sessions. Reference: https://docs.browserbase.com/platform/identity/proxies
2. For the simplest case set the top-level body field proxies: true (Node: bb.sessions.create({ proxies: true }); Python: bb.sessions.create(proxies=True)).
3. Understand the default: with proxies: true Browserbase makes a best-effort attempt to use a US-based proxy, and may route through a nearby country such as Canada if no US proxy is available.
4. For geolocation targeting, pass an array instead of a boolean: proxies: [{ type: "browserbase", geolocation: { country: "US", state: "NY", city: "NEW_YORK" } }].
5. Set geolocation.country to an ISO 3166-1 alpha-2 code - it is the only required geolocation field.
6. Optionally set geolocation.state (US locations only, e.g. NY) and geolocation.city (metro area, e.g. NEW_YORK or LONDON). Both are case-insensitive.
7. If no proxy exists at the exact requested location, Browserbase falls back to the closest available location rather than erroring - verify the observed egress IP in-session if the exact geo matters.
8. Confirm the account is on the Developer plan or higher; built-in and custom proxies are both gated at that tier.
9. Track consumption via the proxyBytes field on the session object, since proxy usage is billed on data transferred.