feat(kafka): add message display ordering

apps/desktop/src/lib/mq/__tests__/kafkaMessageSort.spec.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from "vitest";
+import type { PeekedMessage } from "@/types/mq";
+import { sortKafkaMessagesByPublishTime } from "@/lib/mq/kafkaMessageSort";
+
+function message(position: number, publishTime?: string): PeekedMessage {
+  return {
+    position,
+    messageId: String(position),
+    publishTime,
+    payloadBase64: "",
+    payloadText: `message ${position}`,
+    properties: {},
+    headers: {},
+  };
+}
+
+describe("Kafka message display sorting", () => {
+  it("sorts valid timestamps in either direction without mutating the input", () => {
+    const messages = [message(1, "1000"), message(2, "3000"), message(3, "2000")];
+
+    expect(sortKafkaMessagesByPublishTime(messages, "newest").map(({ position }) => position)).toEqual([2, 3, 1]);
+    expect(sortKafkaMessagesByPublishTime(messages, "oldest").map(({ position }) => position)).toEqual([1, 3, 2]);
+    expect(messages.map(({ position }) => position)).toEqual([1, 2, 3]);
+  });
+
+  it("keeps equal and unavailable timestamps stable after valid timestamps", () => {
+    const messages = [message(1), message(2, "2000"), message(3, "invalid"), message(4, "2000"), message(5, "")];
+
+    expect(sortKafkaMessagesByPublishTime(messages, "newest").map(({ position }) => position)).toEqual([2, 4, 1, 3, 5]);
+    expect(sortKafkaMessagesByPublishTime(messages, "oldest").map(({ position }) => position)).toEqual([2, 4, 1, 3, 5]);
+  });
+});

apps/desktop/src/lib/mq/kafkaMessageSort.ts

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+import type { PeekedMessage } from "@/types/mq";
+
+export type KafkaMessageDisplayOrder = "newest" | "oldest";
+
+function parsePublishTime(value?: string): number | null {
+  if (value == null || value.trim() === "") return null;
+  const timestamp = Number(value);
+  return Number.isFinite(timestamp) ? timestamp : null;
+}
+
+export function sortKafkaMessagesByPublishTime(messages: readonly PeekedMessage[], order: KafkaMessageDisplayOrder): PeekedMessage[] {
+  return messages
+    .map((message, index) => ({ message, index, timestamp: parsePublishTime(message.publishTime) }))
+    .sort((left, right) => {
+      if (left.timestamp == null && right.timestamp != null) return 1;
+      if (left.timestamp != null && right.timestamp == null) return -1;
+      if (left.timestamp != null && right.timestamp != null && left.timestamp !== right.timestamp) {
+        return order === "newest" ? right.timestamp - left.timestamp : left.timestamp - right.timestamp;
+      }
+      return left.index - right.index;
+    })
+    .map(({ message }) => message);
+}