Paperclip Slack Plugin

Slack Chat OS plugin for [Paperclip](https://github.com/paperclipai/paperclip). Notifications, approvals, multi-agent threads, voice-to-task pipelines, custom workflow commands, and proactive agent suggestions. Built on the plugin SDK and the [PR #909](https://github.com/paperclipai/paperclip/pull/909) event bridge.

Phase 1: Notifications + HITL Escalation

Block Kit notifications — issue created/done, approval requested with Approve / Reject / View buttons, agent error, agent online, budget threshold alerts at 80/90/100% (deduped), onboarding milestone for an agent's first run.

Interactive approvals — click → Paperclip API call, message updates inline. Logged as slack:{userid}.

HITL escalation — escalatetohuman posts to a dedicated channel with conversation history, agent reasoning, confidence score. Buttons: Use Suggested Reply, Reply, Override, Dismiss. 15-min timeout with default action (defer, close, autoreply). Customer messages queued during escalation.

Per-type channel routing — approvals, errors, pipeline events to separate channels with default fallback. Per-company overrides take priority.

Daily digest — 9am summary: tasks completed/created, active agents, total cost (from costevent.created), top performer.

Phase 2: Multi-Agent Group Threads

Up to 5 agents per thread, spawned via /clip acp spawn <agent>. @mention routing, reply-to context, most-recently-active fallback. handofftoagent with Approve/Reject buttons. discusswithagent for back-and-forth loops with checkpoints every 5 turns. Stale detection auto-pauses after 5 min idle. Output sequencing prevents interleaving.

Phase 3: Media-to-Task Pipeline