fix: hide system-reminder blocks in backfill + literal tag rendering (#935)

src/tests/cli/userMessageRich.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, test } from "bun:test";
+import { splitSystemReminderBlocks } from "../../cli/components/UserMessageRich";
+
+describe("splitSystemReminderBlocks", () => {
+  test("treats unmatched system-reminder opener as literal user text", () => {
+    const text = "like the <system-reminder> etc included.";
+    const blocks = splitSystemReminderBlocks(text);
+
+    expect(blocks).toEqual([{ text, isSystemReminder: false }]);
+  });
+
+  test("still detects well-formed system-reminder blocks", () => {
+    const blocks = splitSystemReminderBlocks(
+      "before\n<system-reminder>\ncontext\n</system-reminder>\nafter",
+    );
+
+    expect(blocks.some((b) => b.isSystemReminder)).toBe(true);
+    expect(blocks.some((b) => b.text.includes("before"))).toBe(true);
+    expect(blocks.some((b) => b.text.includes("after"))).toBe(true);
+  });
+});