feat(twitter_threads): thread_from_dict + download_media/render_markdown CLIs (end-to-end -m pipeline)

thread_from_dict (JSON wire boundary) round-trips thread_data.json; download_media/render_markdown gain argparse main() + __main__ so the plan Task 5.3 pipeline runs via -m; dual-import added so all modules run standalone or via -m (G5). Pipeline integration test (html->names->render) + CLI tests cover the glue without network. TDD: red -> green (4 pipeline + 29 regression = 33 passed).

scripts/twitter_threads/download_media.py

@@ -1,10 +1,16 @@
 """Download media URLs from ThreadData via stdlib urllib into a local directory."""
 from __future__ import annotations
+import argparse
+import json
+import sys
 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
+try:
+ from scripts.twitter_threads.error_types import ErrorInfo, make_error, Result, PostData, ThreadData, thread_from_dict
+except ImportError:
+ from error_types import ErrorInfo, make_error, Result, PostData, ThreadData, thread_from_dict
 
 def _classify(url: str) -> tuple[str, str]:
  parsed = urlparse(url)
@@ -54,3 +60,30 @@ def download_media(thread: ThreadData, output_dir: Path) -> Result[list[Path]]:
     return Result.err(make_error("WriteError", "download_media", str(e)))
    paths.append(target)
  return Result.ok(paths)
+
+def main(argv: list[str] | None = None) -> int:
+ parser = argparse.ArgumentParser(description="Download media for a Twitter/X thread_data.json.")
+ parser.add_argument("--input", type=Path, required=True, help="thread_data.json path")
+ parser.add_argument("--output", type=Path, required=True, help="media output directory")
+ args = parser.parse_args(argv)
+ try:
+  raw = args.input.read_text(encoding="utf-8")
+ except OSError as e:
+  sys.stderr.write(f"error: ReadError: {e}\n")
+  return 1
+ try:
+  data = json.loads(raw)
+ except json.JSONDecodeError as e:
+  sys.stderr.write(f"error: JsonParseError: {e}\n")
+  return 1
+ thread = thread_from_dict(data)
+ result = download_media(thread, args.output)
+ if not result.is_ok:
+  sys.stderr.write(f"error: {result.error.kind}: {result.error.detail}\n")
+  return 1
+ print(f"downloaded {len(result.data)} file(s) to {args.output}")
+ return 0
+
+
+if __name__ == "__main__":
+ sys.exit(main())