Allow txt export with timestampts

tests/export.test.ts

@@ -1,8 +1,10 @@
 import { describe, expect, test } from "bun:test";
 import {
   exportFilename,
+  formatClockTimestamp,
   formatSrtTimestamp,
   transcriptToSrt,
+  transcriptToTimestampedTxt,
   transcriptToTxt,
 } from "../src/lib/export";
 import type { TranscriptChunk } from "../src/worker/protocol";
@@ -100,6 +102,64 @@ describe("transcriptToSrt", () => {
   });
 });
 
+describe("formatClockTimestamp", () => {
+  test("zero", () => {
+    expect(formatClockTimestamp(0)).toBe("00:00.0");
+  });
+
+  test("pads minutes and seconds", () => {
+    expect(formatClockTimestamp(3.21)).toBe("00:03.2");
+    expect(formatClockTimestamp(65.4)).toBe("01:05.4");
+  });
+
+  test("rounding to tenths carries into the minutes", () => {
+    expect(formatClockTimestamp(59.96)).toBe("01:00.0");
+  });
+
+  test("minutes keep growing past an hour", () => {
+    expect(formatClockTimestamp(3661.5)).toBe("61:01.5");
+  });
+
+  test("clamps negatives to zero", () => {
+    expect(formatClockTimestamp(-1)).toBe("00:00.0");
+  });
+});
+
+describe("transcriptToTimestampedTxt", () => {
+  const chunk = (
+    text: string,
+    start: number,
+    end: number | null,
+  ): TranscriptChunk => ({ text, timestamp: [start, end] });
+
+  test("one bracketed range per line, trailing newline", () => {
+    const txt = transcriptToTimestampedTxt([
+      chunk(" Hello.", 3.21, 7.9),
+      chunk(" World.", 7.9, 12),
+    ]);
+    expect(txt).toBe("[00:03.2 – 00:07.9] Hello.\n[00:07.9 – 00:12.0] World.\n");
+  });
+
+  test("null end omits the range end", () => {
+    expect(transcriptToTimestampedTxt([chunk("Tail", 10, null)])).toBe(
+      "[00:10.0] Tail\n",
+    );
+  });
+
+  test("skips empty and whitespace-only chunks", () => {
+    const txt = transcriptToTimestampedTxt([
+      chunk("  ", 0, 1),
+      chunk("Kept", 1, 2),
+    ]);
+    expect(txt).toBe("[00:01.0 – 00:02.0] Kept\n");
+  });
+
+  test("no captioned chunks yields an empty string", () => {
+    expect(transcriptToTimestampedTxt([])).toBe("");
+    expect(transcriptToTimestampedTxt([chunk(" ", 0, 1)])).toBe("");
+  });
+});
+
 describe("exportFilename", () => {
   test("swaps the extension", () => {
     expect(exportFilename("talk.m4a", "srt")).toBe("talk.srt");
@@ -120,6 +180,15 @@ describe("exportFilename", () => {
     expect(exportFilename(".bashrc", "txt")).toBe(".bashrc.txt");
   });
 
+  test("compound extension keeps timestamped exports distinct", () => {
+    expect(exportFilename("talk.m4a", "timestamps.txt")).toBe(
+      "talk.timestamps.txt",
+    );
+    expect(exportFilename(null, "timestamps.txt")).toBe(
+      "transcript.timestamps.txt",
+    );
+  });
+
   test("null, undefined, and blank fall back to transcript.*", () => {
     expect(exportFilename(null, "srt")).toBe("transcript.srt");
     expect(exportFilename(undefined, "txt")).toBe("transcript.txt");