feat(http-specs): add SSE protocol Spector scenarios

.chronus/changes/iscai-msft-add-sse-spector-scenarios-2026-7-10-14-23-58.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@typespec/http-specs"
+---
+
+Add SSE protocol coverage for event IDs, retry fields, and reconnection

packages/http-specs/spec-summary.md

@@ -5356,6 +5356,88 @@ data: [DONE]
 
 ```
 
+### Streaming_Sse_Protocol_id
+
+- Endpoint: `get /streaming/sse/protocol/id`
+
+An SSE event with an `id` field. The event ID is envelope metadata and is
+not part of the typed event data.
+
+Expected response body (content type `text/event-stream`):
+
+```
+id: event-1
+data: {"message": "hello"}
+
+```
+
+### Streaming_Sse_Protocol_invalidId
+
+- Endpoint: `get /streaming/sse/protocol/invalid-id`
+
+An SSE event with an `id` field containing U+0000 NULL. The field is
+ignored according to the SSE parsing rules.
+
+Expected response body (content type `text/event-stream`):
+
+```
+id: invalid<U+0000 NULL>id
+data: {"message": "hello"}
+
+```
+
+### Streaming_Sse_Protocol_invalidRetry
+
+- Endpoint: `get /streaming/sse/protocol/invalid-retry`
+
+An SSE event with an invalid `retry` field. Since the value contains
+non-ASCII-digit characters, the field is ignored.
+
+Expected response body (content type `text/event-stream`):
+
+```
+retry: not-a-number
+data: {"message": "hello"}
+
+```
+
+### Streaming_Sse_Protocol_reconnect
+
+- Endpoint: `get /streaming/sse/protocol/reconnect`
+
+An SSE stream that resumes after a reconnect. The client sends the most
+recently received event ID in the `Last-Event-ID` request header.
+
+Expected request header:
+
+```
+Last-Event-ID: event-1
+```
+
+Expected response body (content type `text/event-stream`):
+
+```
+id: event-2
+data: {"message": "world"}
+
+```
+
+### Streaming_Sse_Protocol_retry
+
+- Endpoint: `get /streaming/sse/protocol/retry`
+
+An SSE event with a valid `retry` field containing only ASCII digits. The
+field sets the client's reconnection delay and is not part of the typed
+event data.
+
+Expected response body (content type `text/event-stream`):
+
+```
+retry: 1000
+data: {"message": "hello"}
+
+```
+
 ### Streaming_Sse_Retrieve_stream
 
 - Endpoint: `post /streaming/sse/retrieve/stream`

packages/http-specs/specs/streaming/sse/main.tsp

@@ -151,3 +151,97 @@ namespace Retrieve {
   @route("stream")
   op stream(@body request: RetrievalRequest): SSEStream<RetrievalEvents>;
 }
+
+@route("protocol")
+namespace Protocol {
+  model Info {
+    message: string;
+  }
+
+  @events
+  union ProtocolEvents {
+    @Events.contentType("application/json")
+    Info,
+  }
+
+  @scenario
+  @scenarioDoc("""
+    An SSE event with an `id` field. The event ID is envelope metadata and is
+    not part of the typed event data.
+
+    Expected response body (content type `text/event-stream`):
+    ```
+    id: event-1
+    data: {"message": "hello"}
+
+    ```
+    """)
+  @route("id")
+  op id(): SSEStream<ProtocolEvents>;
+
+  @scenario
+  @scenarioDoc("""
+    An SSE event with an `id` field containing U+0000 NULL. The field is
+    ignored according to the SSE parsing rules.
+
+    Expected response body (content type `text/event-stream`):
+    ```
+    id: invalid<U+0000 NULL>id
+    data: {"message": "hello"}
+
+    ```
+    """)
+  @route("invalid-id")
+  op invalidId(): SSEStream<ProtocolEvents>;
+
+  @scenario
+  @scenarioDoc("""
+    An SSE event with a valid `retry` field containing only ASCII digits. The
+    field sets the client's reconnection delay and is not part of the typed
+    event data.
+
+    Expected response body (content type `text/event-stream`):
+    ```
+    retry: 1000
+    data: {"message": "hello"}
+
+    ```
+    """)
+  @route("retry")
+  op retry(): SSEStream<ProtocolEvents>;
+
+  @scenario
+  @scenarioDoc("""
+    An SSE event with an invalid `retry` field. Since the value contains
+    non-ASCII-digit characters, the field is ignored.
+
+    Expected response body (content type `text/event-stream`):
+    ```
+    retry: not-a-number
+    data: {"message": "hello"}
+
+    ```
+    """)
+  @route("invalid-retry")
+  op invalidRetry(): SSEStream<ProtocolEvents>;
+
+  @scenario
+  @scenarioDoc("""
+    An SSE stream that resumes after a reconnect. The client sends the most
+    recently received event ID in the `Last-Event-ID` request header.
+
+    Expected request header:
+    ```
+    Last-Event-ID: event-1
+    ```
+
+    Expected response body (content type `text/event-stream`):
+    ```
+    id: event-2
+    data: {"message": "world"}
+
+    ```
+    """)
+  @route("reconnect")
+  op reconnect(): SSEStream<ProtocolEvents>;
+}

packages/http-specs/specs/streaming/sse/mockapi.ts

@@ -70,3 +70,79 @@ Scenarios.Streaming_Sse_Retrieve_stream = passOnSuccess({
   },
   kind: "MockApiDefinition",
 });
+
+const protocolEvent = (fields: string[]) => Buffer.from(`${fields.join("\n")}\n\n`);
+
+Scenarios.Streaming_Sse_Protocol_id = passOnSuccess({
+  uri: "/streaming/sse/protocol/id",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      rawContent: protocolEvent(["id: event-1", 'data: {"message": "hello"}']),
+      contentType: "text/event-stream",
+    },
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Streaming_Sse_Protocol_invalidId = passOnSuccess({
+  uri: "/streaming/sse/protocol/invalid-id",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      rawContent: protocolEvent(["id: invalid\u0000id", 'data: {"message": "hello"}']),
+      contentType: "text/event-stream",
+    },
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Streaming_Sse_Protocol_retry = passOnSuccess({
+  uri: "/streaming/sse/protocol/retry",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      rawContent: protocolEvent(["retry: 1000", 'data: {"message": "hello"}']),
+      contentType: "text/event-stream",
+    },
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Streaming_Sse_Protocol_invalidRetry = passOnSuccess({
+  uri: "/streaming/sse/protocol/invalid-retry",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      rawContent: protocolEvent(["retry: not-a-number", 'data: {"message": "hello"}']),
+      contentType: "text/event-stream",
+    },
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Streaming_Sse_Protocol_reconnect = passOnSuccess({
+  uri: "/streaming/sse/protocol/reconnect",
+  method: "get",
+  request: {
+    headers: {
+      "last-event-id": "event-1",
+    },
+  },
+  response: {
+    status: 200,
+    body: {
+      rawContent: protocolEvent(["id: event-2", 'data: {"message": "world"}']),
+      contentType: "text/event-stream",
+    },
+  },
+  kind: "MockApiDefinition",
+});