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/render_markdown.py

@@ -1,7 +1,13 @@
 """Render ThreadData into a Markdown file with YAML front-matter."""
 from __future__ import annotations
+import argparse
+import json
+import sys
 from pathlib import Path
-from scripts.twitter_threads.error_types import ErrorInfo, make_error, Result, ThreadData, PostData
+try:
+ from scripts.twitter_threads.error_types import ErrorInfo, make_error, Result, ThreadData, PostData, thread_from_dict
+except ImportError:
+ from error_types import ErrorInfo, make_error, Result, ThreadData, PostData, thread_from_dict
 
 _EM_DASH = "\u2014"
 
@@ -68,4 +74,38 @@ def render_markdown(thread: ThreadData, media_names: dict[str, list[str]], outpu
   output.write_text(content, encoding="utf-8")
  except OSError as e:
   return Result.err(make_error("WriteError", "render_markdown", str(e)))
- return Result.ok(output)
+ return Result.ok(output)
+
+def main(argv: list[str] | None = None) -> int:
+ parser = argparse.ArgumentParser(description="Render a Twitter/X thread_data.json to Markdown.")
+ parser.add_argument("--input", type=Path, required=True, help="thread_data.json path")
+ parser.add_argument("--media-dir", type=Path, required=True, help="media directory to link")
+ parser.add_argument("--output", type=Path, required=True, help="output .md path")
+ 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)
+ media_names: dict[str, list[str]] = {}
+ for post in thread.posts:
+  if args.media_dir.exists():
+   files = sorted(f.name for f in args.media_dir.glob(f"{post.post_id}_*"))
+   if files:
+    media_names[post.post_id] = files
+ result = render_markdown(thread, media_names, args.output)
+ if not result.is_ok:
+  sys.stderr.write(f"error: {result.error.kind}: {result.error.detail}\n")
+  return 1
+ print(str(args.output))
+ return 0
+
+
+if __name__ == "__main__":
+ sys.exit(main())