fetch_thread_from_url now passes -o conversations=true (full threads, not single tweets), sorts posts chronologically, and sets root_post_id to the URL's target tweet. render_markdown builds front-matter from the target (root_post_id) post, not the earliest conversation tweet (fixes wrong @handle). Added dedupe_corpus.py: keeps deepest thread per conversation, deletes duplicates, keeps+marks unique branches (branch_of) + writes threads_index.json. 33 tests pass.
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).
Added standalone Result[T] (frozen+slots, ok/err classmethods, is_ok) to error_types.py per canonical AND-over-OR error_handling.md (not the video_analysis _Ok|_Err sum type). render_markdown renders YAML front-matter from root post, per-post ## sections with reply markers, quote blockquotes, and ./media/<name> links; media_names mapping keeps render decoupled from download_media. TDD: red (no Result) -> green (7 render + 9 types passed).