Gateway first-byte timeout now applies to every upstream type when set; upstreams accept a models list

What

The apps gateway sits between Claude Code and the model providers it forwards requests to, which are called upstreams. Its first-byte timeout setting, timeouts.upstream_ttfb_ms, controls how long the gateway waits for the first piece of a reply. It has been reworked, and upstreams gained new options.

• timeouts.upstream_ttfb_ms is now optional in the gateway config. The schema no longer fills in a default. A default of 120000 milliseconds is still applied, but the gateway now records whether the operator wrote the value themselves.
• The timeout, capped, is now passed on the upstream call for streaming requests and count_tokens requests. A request that times out returns an error message that names timeouts.upstream_ttfb_ms.
• When an operator has set the value, the gateway logs an info message at startup. The message says the setting now also applies to streaming and count_tokens requests on non-anthropic upstreams. Before, the timeout applied only to provider: anthropic upstreams.
• The anthropic, bedrock, anthropicAws, anthropicGoogleCloud, vertex and foundry upstreams now accept a models list.
• count_tokens (a request that asks how many tokens a prompt uses) on Bedrock upstreams is now handled. Before, it always returned a 501 "not supported" error.

Why

If you run the gateway with non-Anthropic upstreams and have set timeouts.upstream_ttfb_ms, the timeout now also applies to those upstreams. Slow first replies there can therefore fail where they did not before. Bedrock users can now get token counts through the gateway.