[arandito]

Description

Adds support for the @endpoint trait's hostPrefix and @hostLabel members across all protocols.

Added

• The request pipeline expands the operation's host prefix once per call and prepends it to each attempt's resolved endpoint host before signing. The prefix also applies to a configured endpoint_uri.
• HOST_PREFIX context property in smithy_core.endpoints, holding the expanded prefix.
• An invalid or missing host label raises EndpointResolutionError before the request is sent.
• disable_host_prefix_injection config field, generated only for services with @endpoint operations.
• Codegen strips S3 Control's {AccountId}. host prefix, since its endpoint rules already place the account ID.

Removed (breaking, smithy-http)

• HostPrefixSerializer and Binding.HOST. @hostLabel no longer changes where a member is serialized.
• HTTPOperationSchemaMetadata.host_prefix and the endpoint_trait parameters on the HTTP serializers.
• Reasoning: Host prefixes were previously only handled in the REST serializers and set_service_endpoint overwrote the host they built. The pipeline now handles host prefixes for every protocol. Additionally, the Smithy spec states that hostLabel must not affect a member's serialization.

Testing

• Host prefix protocol tests and endpoint tests pass. They were xfailed before support was added.
• Added unit test coverage for the new behavior.
• Regenerated the existing clients plus S3 and S3 Control with this change. Their endpoint tests pass, including the previously xfailed S3 WriteGetObjectResponse and S3 Control {AccountId}. endpoint cases.

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[kuhe]

AWS_EC2 is not defined or imported in ec2query._private.schemas

what's this warning about? isn't this the service schema, which should exist?

[arandito]

Looks like a false positive that's already on develop. AWS_EC2 lives in a lazily loaded schema partition, which the static canonical-imports check doesn't check.