Harden Responses SSE framing against partial chunk boundaries

Follow-up review found two real framing hazards in the handler-layer framer: it could flush a partial `data:` payload before the JSON was complete, and it could inject an extra newline before chunks that already began with `\n`/`\r\n`. This commit tightens the framer so it only emits undelimited events when the buffered `data:` payload is already valid JSON (or `[DONE]`), skips newline injection for chunks that already start with a line break, and avoids the heavier `bytes.Split` path while scanning SSE fields. The regression suite now covers split `data:` payload chunks, newline-prefixed chunks, and dropping incomplete trailing data on flush, so the original Responses fix remains intact while the review concerns are explicitly locked down. Constraint: Keep the follow-up limited to handler-layer framing and tests Rejected: Ignore the review and rely on current executor chunk shapes | leaves partial data payload corruption possible Rejected: Build a fully generic SSE parser | wider change than needed for the identified risks Confidence: high Scope-risk: narrow Reversibility: clean Directive: Do not emit undelimited Responses SSE events unless buffered `data:` content is already complete and valid Tested: /tmp/go1.26.1/go/bin/go test ./sdk/api/handlers/openai -count=1 Tested: /tmp/go1.26.1/go/bin/go test ./sdk/api/handlers -count=1 Tested: /tmp/go1.26.1/go/bin/go vet ./sdk/api/handlers/... Not-tested: Full repository test suite outside sdk/api/handlers packages
2026-04-02 20:39:49 +08:00
parent abc293c642
commit 108895fc04
2 changed files with 94 additions and 5 deletions
@@ -96,3 +96,47 @@ func TestForwardResponsesStreamPreservesValidFullSSEEventChunks(t *testing.T) {
 		t.Fatalf("unexpected full-event framing.\nGot:  %q\nWant: %q", got, string(chunk))
 	}
 }
+
+func TestForwardResponsesStreamBuffersSplitDataPayloadChunks(t *testing.T) {
+	h, recorder, c, flusher := newResponsesStreamTestHandler(t)
+
+	data := make(chan []byte, 2)
+	errs := make(chan *interfaces.ErrorMessage)
+	data <- []byte("data: {\"type\":\"response.created\"")
+	data <- []byte(",\"response\":{\"id\":\"resp-1\"}}")
+	close(data)
+	close(errs)
+
+	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)
+
+	got := recorder.Body.String()
+	want := "data: {\"type\":\"response.created\",\"response\":{\"id\":\"resp-1\"}}\n\n\n"
+	if got != want {
+		t.Fatalf("unexpected split-data framing.\nGot:  %q\nWant: %q", got, want)
+	}
+}
+
+func TestResponsesSSENeedsLineBreakSkipsChunksThatAlreadyStartWithNewline(t *testing.T) {
+	if responsesSSENeedsLineBreak([]byte("event: response.created"), []byte("\n")) {
+		t.Fatal("expected no injected newline before newline-only chunk")
+	}
+	if responsesSSENeedsLineBreak([]byte("event: response.created"), []byte("\r\n")) {
+		t.Fatal("expected no injected newline before CRLF chunk")
+	}
+}
+
+func TestForwardResponsesStreamDropsIncompleteTrailingDataChunkOnFlush(t *testing.T) {
+	h, recorder, c, flusher := newResponsesStreamTestHandler(t)
+
+	data := make(chan []byte, 1)
+	errs := make(chan *interfaces.ErrorMessage)
+	data <- []byte("data: {\"type\":\"response.created\"")
+	close(data)
+	close(errs)
+
+	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)
+
+	if got := recorder.Body.String(); got != "\n" {
+		t.Fatalf("expected incomplete trailing data to be dropped on flush.\nGot: %q", got)
+	}
+}