What problem does it solve? Adding a new issue-thread interaction kind to Paperclip touches four layers (shared contract, server service, UI card, and CLI/MCP/plugin SDK helpers), and missing any one of them causes broken agent flows or drifting behavior. This Skill gives contributors a proven order of operations, invariants, and checklists so a new interaction kind lands correctly the first time. ## Core Features & Use Cases - Layered implementation plan: Walks through the shared contract (constants, types, Zod validators), server service and routes, UI card and issue-thread wiring, and CLI/MCP/plugin SDK helpers in the correct order. - Canonical prior art: Points to the checkbox confirmation rollout (commit 4d5322c82, PR #7649) and the four existing kinds as reference implementations to copy rather than reinvent. - Invariants and anti-patterns: Codifies board-only resolution, company scoping, stale-target expiration, supersede-on-user-comment, idempotency keys, and continuation wake policies, plus review-observed mistakes to avoid. - Use Case: A contributor needs to add a structured rating card to issue threads. Following this Skill, they add the kind to the shared validators first, extend the server service with stale/supersede handling, wire the UI card with fixtures and Storybook entries, then ship CLI, MCP, and plugin SDK support with a focused vitest run. ## Quick Start Ask the agent to walk you through adding a new issue-thread interaction kind to the Paperclip repo, starting from the shared contract in packages/shared.