refactor: centralize slack threading helpers

src/slack/threading.test.ts

@@ -0,0 +1,48 @@
+import { describe, expect, it } from "vitest";
+
+import { resolveSlackThreadTargets } from "./threading.js";
+
+describe("resolveSlackThreadTargets", () => {
+  it("threads replies when message is already threaded", () => {
+    const { replyThreadTs, statusThreadTs } = resolveSlackThreadTargets({
+      replyToMode: "off",
+      message: {
+        type: "message",
+        channel: "C1",
+        ts: "123",
+        thread_ts: "456",
+      },
+    });
+
+    expect(replyThreadTs).toBe("456");
+    expect(statusThreadTs).toBe("456");
+  });
+
+  it("threads top-level replies when mode is all", () => {
+    const { replyThreadTs, statusThreadTs } = resolveSlackThreadTargets({
+      replyToMode: "all",
+      message: {
+        type: "message",
+        channel: "C1",
+        ts: "123",
+      },
+    });
+
+    expect(replyThreadTs).toBe("123");
+    expect(statusThreadTs).toBe("123");
+  });
+
+  it("keeps status threading even when reply threading is off", () => {
+    const { replyThreadTs, statusThreadTs } = resolveSlackThreadTargets({
+      replyToMode: "off",
+      message: {
+        type: "message",
+        channel: "C1",
+        ts: "123",
+      },
+    });
+
+    expect(replyThreadTs).toBeUndefined();
+    expect(statusThreadTs).toBe("123");
+  });
+});