[Fix] Slack block context appears in task messages

[roomote-roomote]

​Opened on behalf of @daniel-lxs. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

Inbound Slack messages now keep their existing attachment and structured-block enrichment separate from authored text. Prompt assembly injects that extra information in a dedicated <slack_message_context> sibling while <slack_message> keeps the normal user turn.

Standard and Fast Slack entry paths both pass the same enrichment through the agent-only context boundary. Transcript parsing recognizes the explicit wrapper grammar, renders only the authored message in the task UI, and leaves malformed input untouched.

Why this change was made

Slack can provide useful information outside its top-level text. Appending that enrichment directly to the message preserved context for the agent but exposed internal labels such as Slack block text: in the user-visible transcript.

Impact

Roomote handles Slack enrichment like other injected context: the agent receives it, but task message bubbles show only the authored Slack text. Existing stored transcripts remain unchanged.

Screenshots

[roomote-community]

No new code issues found. See task

• Bare block links with targets that differ from fallback links are preserved.
• Markdown-linked fallback URLs containing parentheses are parsed correctly (packages/slack/src/forwarded-message-context.ts:50).
• Fast-mode parsing uses authored text for command/question handling and keeps Slack block/attachment context in the agent-only prompt (apps/api/src/handlers/slack/events/fast-agent.ts:98).

_{Reviewed 0296005}

[roomote-roomote]

Fixed the failing Test check in c458aab. Ordinary SlackNotifier.getMessage() results retain their legacy object shape, while authoredText and agentContext are emitted when structured Slack context actually exists. The exact failing test file passes all 88 tests, the full Slack package passes all 403 tests, and the replacement GitHub Test check is now passing.