fix: carry reply tags across streamed chunks

src/auto-reply/reply/streaming-directives.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it } from "vitest";
+import { createStreamingDirectiveAccumulator } from "./streaming-directives.js";
+
+describe("createStreamingDirectiveAccumulator", () => {
+  it("stashes reply_to_current until a renderable chunk arrives", () => {
+    const accumulator = createStreamingDirectiveAccumulator();
+
+    expect(accumulator.consume("[[reply_to_current]]")).toBeNull();
+
+    const result = accumulator.consume("Hello");
+    expect(result?.text).toBe("Hello");
+    expect(result?.replyToCurrent).toBe(true);
+    expect(result?.replyToTag).toBe(true);
+  });
+
+  it("handles reply tags split across chunks", () => {
+    const accumulator = createStreamingDirectiveAccumulator();
+
+    expect(accumulator.consume("[[reply_to_")).toBeNull();
+
+    const result = accumulator.consume("current]] Yo");
+    expect(result?.text).toBe("Yo");
+    expect(result?.replyToCurrent).toBe(true);
+    expect(result?.replyToTag).toBe(true);
+  });
+
+  it("propagates explicit reply ids across chunks", () => {
+    const accumulator = createStreamingDirectiveAccumulator();
+
+    expect(accumulator.consume("[[reply_to: abc-123]]")).toBeNull();
+
+    const result = accumulator.consume("Hi");
+    expect(result?.text).toBe("Hi");
+    expect(result?.replyToId).toBe("abc-123");
+    expect(result?.replyToTag).toBe(true);
+  });
+});