📝 Update Skill for Server Sent Events

fastapi/.agents/skills/fastapi/SKILL.md

@@ -521,6 +521,56 @@ async def stream_items() -> AsyncIterable[Item]:
         yield item
 ```
 
+## Server-Sent Events (SSE)
+
+To stream Server-Sent Events, use `response_class=EventSourceResponse` and `yield` items from the endpoint.
+
+Plain objects are automatically JSON-serialized as `data:` fields, declare the return type so the serialization is done by Pydantic:
+
+```python
+from collections.abc import AsyncIterable
+
+from fastapi import FastAPI
+from fastapi.sse import EventSourceResponse
+from pydantic import BaseModel
+
+app = FastAPI()
+
+
+class Item(BaseModel):
+    name: str
+    price: float
+
+
+@app.get("/items/stream", response_class=EventSourceResponse)
+async def stream_items() -> AsyncIterable[Item]:
+    yield Item(name="Plumbus", price=32.99)
+    yield Item(name="Portal Gun", price=999.99)
+```
+
+For full control over SSE fields (`event`, `id`, `retry`, `comment`), yield `ServerSentEvent` instances:
+
+```python
+from collections.abc import AsyncIterable
+
+from fastapi import FastAPI
+from fastapi.sse import EventSourceResponse, ServerSentEvent
+
+app = FastAPI()
+
+
+@app.get("/events", response_class=EventSourceResponse)
+async def stream_events() -> AsyncIterable[ServerSentEvent]:
+    yield ServerSentEvent(data={"status": "started"}, event="status", id="1")
+    yield ServerSentEvent(data={"progress": 50}, event="progress", id="2")
+```
+
+Use `raw_data` instead of `data` to send pre-formatted strings without JSON encoding:
+
+```python
+yield ServerSentEvent(raw_data="plain text line", event="log")
+```
+
 ## Stream bytes
 
 To stream bytes, declare a `response_class=` of `StreamingResponse` or a sub-class, and use `yield` to return the data.