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THE empty-body root cause. Patreon deprecated the flat `content` HTML field — it returns null on the feed AND the detail endpoint, for every post type (confirmed against the live API: all 135 StickySpoodge posts, text_only/ image_file/poll alike). The real body now lives in `content_json_string` (a ProseMirror/TipTap doc), returned only under the DEFAULT post fieldset — a sparse fields[post]=content request omits it. Not credential, not post_type: a request shape gone stale. - NEW utils/prosemirror.py: ProseMirror doc -> HTML (paragraphs, marks bold/italic/underline/strike/code/link, hardBreak, inline images, lists, headings; unknown nodes degrade to children). post_body_html(attrs) = the one resolver: legacy content HTML else convert content_json_string. - patreon_client: add content_json_string to the feed _FIELDS_POST; rewrite fetch_post_detail_content to use the DEFAULT fieldset (no sparse fields[post]) and resolve via post_body_html (replaces the wrong sparse req + full-fetch fallback). - patreon_downloader._write_sidecar_data: resolve body via post_body_html (feed content_json_string) before the detail-fetch; memoize resolved HTML. - tests: prosemirror converter unit tests; client legacy + content_json_string paths; contract pins content_json_string. Inline <img> nodes carry the CDN filehash → bodies now feed Phase-2 localization. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>