Introduce `ServerSentEvent[Data]` so endpoints that yield typed SSE
events get a `contentSchema` in the OpenAPI spec reflecting the data
payload type, while retaining full control over SSE fields (`event`,
`id`, `retry`, `comment`).
- `ServerSentEvent` now inherits from `Generic[Data]` with `data: Data`
- `validate_default=True` ensures `ServerSentEvent[Item]()` raises a
ValidationError (data is effectively required when Data is concrete)
- `ServerSentEvent[Item | None]` allows optional data; bare
`ServerSentEvent` is fully backward compatible (`Data=Any`)
- Added `get_sse_data_type()` helper (uses Pydantic's
`__pydantic_generic_metadata__`) to extract `Data` from a
parameterized `ServerSentEvent[Data]` annotation
- Routing layer now extracts `Data` from `ServerSentEvent[Data]` and
uses it as `stream_item_type`, feeding it into the existing OpenAPI
`contentSchema` pipeline
- Added tutorial006 and corresponding snapshot test
- Extended test_sse.py with generic SSE unit and app-level tests
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
Ben Mosher
e9212d8483