Overview

Add a MongoExtensionStreamType enum to the API header that identifies the two streams a multi-stream extension source can produce.

Background

The new $_documentResultsAndMetadata container routes documents from an extension source to two consumers via an Exchange keyed on a _streamType field. The enum defines the two stream type constants (\$kDocResult = 0, kMetaResult = 1) that extensions use when tagging documents and that the SDK's ExecAggStageResultsAndMetadataSource class exposes as a typed enum.

Scope of Work

• Add MongoExtensionStreamType enum with values:
  • kMongoExtensionStreamTypeDocResult = 0
  • kMongoExtensionStreamTypeMetaResult = 1

Acceptance Criteria

• Enum is present in api.h and usable from both host and extension code
• Values are stable (0 and 1) to match Exchange kKeyRange boundary configuration