After removing the Typing reaction, add CheckMark on success or CrossMark
on failure so teachers can see completion on the source message without
opening the card.
- Create MessageBatcher: debounce 600ms, adaptive delay for long chunks,
max 8 messages/4000 chars before immediate flush, per (chatId, sender) key
- Integrate into trigger: text messages enqueued, slash commands and
file/image bypass batching, locked projects respond immediately
- Add unit tests (8) for batcher lifecycle and edge cases
- Add buildOutboundPayload: detect markdown format, isolate code blocks,
force plain text for tables, fallback from post to text on API rejection
- Add addReaction/removeReaction for processing status lifecycle
- Replace THUMBSUP with Typing→(remove on success | CrossMark on failure)
- Add unit tests for markdown rendering (15) and reactions (6)
hongjr03