Type inconsistency in EventMetadataFilter TypedDict

[jariy17]

Description

In src/bedrock_agentcore/memory/models/filters.py, the EventMetadataFilter TypedDict defines operator: OperatorType (an enum), but the actual value stored is a string.

class EventMetadataFilter(TypedDict):
    left: LeftExpression
    operator: OperatorType  # Type says enum
    right: Optional[RightExpression]

The build_expression method correctly converts the enum to a string:

filter = {"operator": operator.value}  # Stores string, not enum

Ramifications

1. Type hint is misleading - The TypedDict suggests operator holds an OperatorType enum, but it actually holds a string like "EQUALS_TO"

2. Potential runtime error - If a user follows the type hint and passes an enum directly (without using build_expression), boto3 will fail to serialize it since enums are not JSON serializable

3. Type checker inconsistency - Static type checkers like mypy may produce warnings or miss actual type errors due to this mismatch