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.