Work/Slack Preview
Post in #launch that the demo moved to 3pm, but let me see it first.
Claude · Slack Previewpreview_slack_message
Reply to Claude…
+Claude Fable 5
MCP app · No. 002
Slack Preview
Draft a Slack message, see it in channel context, and post it only after a human clicks Send.
About this appDeliberately narrowed to one widget: a send-message preview that shows the draft inside real channel context. Preview state persists in Convex, so the card survives remounts; Slack tokens stay in WorkOS Vault.
0.1.0app · MCP SDK 1.29.0
OriginRailway · production
FrameworkTypeScript · MCP SDK 1.29.0 · Express
TransportStreamable HTTP
AuthWorkOS AuthKit + Vault (Slack OAuth)
StateConvex (persistent previews)
Endpointslack-preview-message-mcp-app-production.up.railway.app/mcp
Tools (3)
preview_slack_messagerenders the preview; autoAccept sends immediately
refresh_slack_preview_statereloads a persisted preview and channel context
send_slack_preview_messageposts after the user clicks Send
Widgets (1)
slack-preview-widgetchannel-context preview with confirmation flow