fix: prevent duplicate agent event emission

src/gateway/openai-http.e2e.test.ts

@@ -462,6 +462,39 @@ describe("OpenAI-compatible HTTP API (e2e)", () => {
     }
   });
 
+  it("preserves repeated identical deltas when streaming SSE", async () => {
+    agentCommand.mockImplementationOnce(async (opts: unknown) => {
+      const runId = (opts as { runId?: string } | undefined)?.runId ?? "";
+      emitAgentEvent({ runId, stream: "assistant", data: { delta: "hi" } });
+      emitAgentEvent({ runId, stream: "assistant", data: { delta: "hi" } });
+      return { payloads: [{ text: "hihi" }] } as never;
+    });
+
+    const port = await getFreePort();
+    const server = await startServer(port);
+    try {
+      const res = await postChatCompletions(port, {
+        stream: true,
+        model: "clawdbot",
+        messages: [{ role: "user", content: "hi" }],
+      });
+      expect(res.status).toBe(200);
+      const text = await res.text();
+      const data = parseSseDataLines(text);
+      const jsonChunks = data
+        .filter((d) => d !== "[DONE]")
+        .map((d) => JSON.parse(d) as Record<string, unknown>);
+      const allContent = jsonChunks
+        .flatMap((c) => (c.choices as Array<Record<string, unknown>> | undefined) ?? [])
+        .map((choice) => (choice.delta as Record<string, unknown> | undefined)?.content)
+        .filter((v): v is string => typeof v === "string")
+        .join("");
+      expect(allContent).toBe("hihi");
+    } finally {
+      await server.close({ reason: "test done" });
+    }
+  });
+
   it("streams SSE chunks when stream=true (fallback when no deltas)", async () => {
     agentCommand.mockResolvedValueOnce({
       payloads: [{ text: "hello" }],