The endpoint answers a probe that exceeds HEALTH_CHECK_TIMEOUT_SECONDS with
HTTP 200 and an in-body "Timeout exceeded", which the harness's status-code
rerun policy cannot see. The suite's parallel Bedrock load can push a Mantle
probe past that cap transiently, so only that exact error is retried, three
bounded attempts with visible prints; any other error verdict still fails
immediately.
Adds live e2e coverage for the Bedrock combinations behind recent customer
incidents: llm_provider-* response-header forwarding on /chat/completions
(nonstream and stream), regional us.anthropic.* inference-profile ids over
the invoke route, and the Admin UI Test Connection probe for a
responses-mode Bedrock Mantle deployment. Registers the matching cells in
the coverage registry and publishes the provider x feature matrix table in
its README.
