diff --git a/apps/web/src/lib/fmt.test.ts b/apps/web/src/lib/fmt.test.ts
new file mode 100644
index 0000000..014d8d5
--- /dev/null
+++ b/apps/web/src/lib/fmt.test.ts
@@ -0,0 +1,83 @@
+import { describe, expect, it } from "vitest";
+import {
+  daysUntil,
+  dueLabel,
+  initials,
+  snoozePreset,
+  snoozeUntilLabel,
+  visibleTags,
+} from "./fmt.js";
+
+describe("initials", () => {
+  it.each([
+    ["Ada Lovelace", "AL"],
+    ["ada", "AD"],
+    ["  ada   byron lovelace  ", "AL"],
+    ["", "?"],
+    ["   ", "?"],
+  ])("formats %j as %s", (name, expected) => {
+    expect(initials(name)).toBe(expected);
+  });
+});
+
+describe("visibleTags", () => {
+  it("drops ext: tags and preserves the remaining tags in order", () => {
+    const tags = ["ext:clickup:123", "bug", "external", "ext:", "team:design"];
+    expect(visibleTags(tags)).toEqual(["bug", "external", "team:design"]);
+  });
+});
+
+describe("daysUntil and dueLabel", () => {
+  const now = new Date(2026, 0, 7, 15).getTime();
+
+  it.each([
+    [new Date(2026, 0, 6, 9), -1, "Yesterday"],
+    [new Date(2026, 0, 7, 9), 0, "Today"],
+    [new Date(2026, 0, 8, 9), 1, "Tomorrow"],
+    [new Date(2026, 0, 9, 9), 2, "Fri"],
+    [new Date(2026, 0, 10, 9), 3, "Sat"],
+    [new Date(2026, 0, 11, 9), 4, "Sun"],
+    [new Date(2026, 0, 12, 9), 5, "Mon"],
+    [new Date(2026, 0, 13, 9), 6, "Tue"],
+    [new Date(2026, 0, 14, 9), 7, "14 Jan"],
+    [new Date(2026, 2, 12, 9), 64, "12 Mar"],
+    [new Date(2027, 0, 7, 9), 365, "7 Jan 27"],
+  ])("formats %s (%i days away) as %s", (date, days, label) => {
+    expect(daysUntil(date.getTime(), now)).toBe(days);
+    expect(dueLabel(date.getTime(), now)).toBe(label);
+  });
+});
+
+describe("snoozePreset", () => {
+  it.each([
+    {
+      day: "Wednesday",
+      now: new Date(2026, 0, 7, 15, 30, 45, 123),
+      tomorrow: new Date(2026, 0, 8, 9),
+      week: new Date(2026, 0, 12, 9),
+    },
+    {
+      day: "Monday before 9am",
+      now: new Date(2026, 0, 5, 7, 30, 45, 123),
+      tomorrow: new Date(2026, 0, 6, 9),
+      week: new Date(2026, 0, 12, 9),
+    },
+  ])("returns tomorrow and next Monday at 9am from $day", ({ now, tomorrow, week }) => {
+    expect(snoozePreset("tomorrow", now.getTime())).toBe(tomorrow.getTime());
+    expect(snoozePreset("week", now.getTime())).toBe(week.getTime());
+  });
+});
+
+describe("snoozeUntilLabel", () => {
+  const now = new Date(2026, 0, 7, 15).getTime();
+
+  it.each([
+    [new Date(2026, 0, 6, 9), "Snoozed until yesterday"],
+    [new Date(2026, 0, 7, 9), "Snoozed until today"],
+    [new Date(2026, 0, 8, 9), "Snoozed until tomorrow"],
+    [new Date(2026, 0, 9, 9), "Snoozed until Fri"],
+    [new Date(2026, 2, 12, 9), "Snoozed until 12 Mar"],
+  ])("formats %s as %s", (date, expected) => {
+    expect(snoozeUntilLabel(date.getTime(), now)).toBe(expected);
+  });
+});