After merging develop, git-sync's markdown converter still predated two
editor features and silently dropped them on every sync:
- Spoiler mark (#259): had no schema entry, so `<span data-spoiler>` from
the canonical lossless form re-parsed as plain text and the mark was
lost. Register a Spoiler mark mirroring @docmost/editor-ext + the MCP
schema, and emit `<span data-spoiler="true">…</span>` on PM->MD.
- Image caption (#221): the converter assumed no caption attribute existed
(the branch was dead). The image schema now carries a plain-text caption
(data-caption); register it and route a captioned image through the raw
<img> form (same lossless convention as the other Docmost image attrs).
Caption-less images keep the lighter `` form.
Both survive PM->MD->PM unchanged; raw `<span data-spoiler>` / `<img
data-caption>` in incoming markdown parse back. New round-trip tests in
markdown-roundtrip-spoiler-caption.test.ts; schema-surface snapshot updated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
claude code agent 227