diff --git a/scripts/twitter_threads/download_media.py b/scripts/twitter_threads/download_media.py
new file mode 100644
index 00000000..3a042951
--- /dev/null
+++ b/scripts/twitter_threads/download_media.py
@@ -0,0 +1,56 @@
+"""Download media URLs from ThreadData via stdlib urllib into a local directory."""
+from __future__ import annotations
+from pathlib import Path
+from urllib.request import urlopen
+from urllib.error import URLError
+from urllib.parse import urlparse, parse_qs
+from scripts.twitter_threads.error_types import ErrorInfo, make_error, Result, PostData, ThreadData
+
+def _classify(url: str) -> tuple[str, str]:
+ parsed = urlparse(url)
+ path = parsed.path
+ if "video.twimg.com" in parsed.netloc or path.endswith(".mp4"):
+  if "tweet_video" in path:
+   return ("gif", "mp4")
+  return ("vid", "mp4")
+ qs = parse_qs(parsed.query)
+ fmt = qs.get("format", [""])[0]
+ if fmt:
+  return ("img", fmt)
+ if "." in path:
+  return ("img", path.rsplit(".", 1)[-1])
+ return ("img", "jpg")
+
+def media_names_for_post(post: PostData) -> list[str]:
+ counters: dict[str, int] = {}
+ names: list[str] = []
+ for url in post.media_urls:
+  kind, ext = _classify(url)
+  counters[kind] = counters.get(kind, 0) + 1
+  names.append(f"{post.post_id}_{kind}{counters[kind]}.{ext}")
+ return names
+
+def download_media(thread: ThreadData, output_dir: Path) -> Result[list[Path]]:
+ try:
+  output_dir.mkdir(parents=True, exist_ok=True)
+ except OSError as e:
+  return Result.err(make_error("WriteError", "download_media", str(e)))
+ paths: list[Path] = []
+ for post in thread.posts:
+  names = media_names_for_post(post)
+  for url, name in zip(post.media_urls, names):
+   target = output_dir / name
+   if target.exists() and target.stat().st_size > 0:
+    paths.append(target)
+    continue
+   try:
+    with urlopen(url) as resp:
+     data = resp.read()
+   except URLError as e:
+    return Result.err(make_error("HttpError", "download_media", str(e)))
+   try:
+    target.write_bytes(data)
+   except OSError as e:
+    return Result.err(make_error("WriteError", "download_media", str(e)))
+   paths.append(target)
+ return Result.ok(paths)
diff --git a/tests/test_twitter_threads_media.py b/tests/test_twitter_threads_media.py
new file mode 100644
index 00000000..e5f4401a
--- /dev/null
+++ b/tests/test_twitter_threads_media.py
@@ -0,0 +1,82 @@
+"""Tests for scripts.twitter_threads.download_media: naming and HTTP download contract."""
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import patch, MagicMock
+from urllib.error import URLError
+
+import pytest
+
+from scripts.twitter_threads.error_types import PostMetrics, PostData, ThreadData
+from scripts.twitter_threads.download_media import media_names_for_post, download_media
+
+
+class _FakeResp:
+ def __init__(self, data: bytes) -> None:
+  self._data = data
+ def read(self) -> bytes:
+  return self._data
+ def __enter__(self) -> "_FakeResp":
+  return self
+ def __exit__(self, *a: object) -> bool:
+  return False
+
+
+def _post(post_id: str, media_urls: tuple[str, ...]) -> PostData:
+ metrics = PostMetrics(reply_count=0, repost_count=0, like_count=0, view_count=None)
+ return PostData(post_id=post_id, author="Tim", handle="NOTimothyLottes", text="t", timestamp="2024-02-01T00:00:00Z", media_urls=media_urls, reply_to_id=None, quote_of_id=None, metrics=metrics)
+
+
+def test_media_names_for_post() -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large", "https://pbs.twimg.com/media/B?format=png&name=large"))
+ assert media_names_for_post(post) == ["123_img1.jpg", "123_img2.png"]
+
+
+def test_media_names_video() -> None:
+ post = _post("123", ("https://video.twimg.com/ext_tw_video/1/pu/vid/1280x720/1234567890.mp4",))
+ assert media_names_for_post(post) == ["123_vid1.mp4"]
+
+
+def test_download_naming(tmp_path: Path) -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large", "https://pbs.twimg.com/media/B?format=png&name=large"))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ with patch("scripts.twitter_threads.download_media.urlopen", return_value=_FakeResp(b"bytes")):
+  result = download_media(thread, tmp_path)
+ assert result.is_ok
+ assert (tmp_path / "123_img1.jpg").exists()
+ assert (tmp_path / "123_img2.png").exists()
+ assert result.data is not None
+ names = [p.name for p in result.data]
+ assert "123_img1.jpg" in names
+ assert "123_img2.png" in names
+
+
+def test_download_video_naming(tmp_path: Path) -> None:
+ post = _post("123", ("https://video.twimg.com/ext_tw_video/1/pu/vid/1280x720/1234567890.mp4",))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ with patch("scripts.twitter_threads.download_media.urlopen", return_value=_FakeResp(b"vid")):
+  result = download_media(thread, tmp_path)
+ assert (tmp_path / "123_vid1.mp4").exists()
+
+
+def test_download_idempotent(tmp_path: Path) -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large",))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ name = media_names_for_post(post)[0]
+ (tmp_path / name).write_bytes(b"already")
+ mock_urlopen = MagicMock()
+ with patch("scripts.twitter_threads.download_media.urlopen", mock_urlopen):
+  result = download_media(thread, tmp_path)
+ assert result.is_ok
+ mock_urlopen.assert_not_called()
+ assert (tmp_path / name).read_bytes() == b"already"
+
+
+def test_download_http_error(tmp_path: Path) -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large",))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ with patch("scripts.twitter_threads.download_media.urlopen", side_effect=URLError("boom")):
+  result = download_media(thread, tmp_path)
+ assert result.is_ok is False
+ assert result.error is not None
+ assert result.error.kind == "HttpError"
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