WebSockets & Realtime State Synchronization

What it does

WebSockets & Realtime State Synchronization is a Cursor skill: a SKILL.md playbook that AgenticKit installs at .cursor/skills/realtime-websockets. Cursor's agent loads it when the task matches the skill description, instead of stuffing the same rules into every chat.

Realtime communication standards for WebSockets and SSE, handling disconnections, state resync, channel subscription, and heartbeat pings.

Socket.io, Server-Sent Events, connection heartbeat, and reconnection logic. The file is domain knowledge, not a slash macro. You do not type it. The agent reads it when the job is realtime websockets.

Why it exists

Default Cursor has no memory of how your team ships code, schema, and tests. Founders paste the same conventions into chat, then watch the model drift on the next turn. This skill exists so those conventions live on disk and load only when relevant.

It ships in the Engineering Kit. It is wired to the Realtime Systems Lead (realtime-engineer) and Senior Backend Architect (backend-architect) agents. It is wired to the /realtime-feature: WebSockets & Realtime State Synchronizer and /llm-chat: Streaming AI Chat Assistant Interface commands. That graph is the point: the skill is the standard, the agent is the role, the command is the trigger.

When to use it

• Use WebSockets & Realtime State Synchronization when the work is specifically about socket.io, server-sent events, connection heartbeat, and reconnection logic.
• Load it before a long session that will touch this surface more than once. A one-line edit does not need the full playbook.
• Use it on production SaaS work (multi-tenant apps, paid features, anything that will be reviewed) rather than a throwaway prototype.

When not to use it

• Do not treat the skill as a replacement for a slash command. Skills teach. Commands run a pipeline.
• Do not paste the whole SKILL.md into chat. If Cursor is not loading it, fix the description or invoke the matching command.
• Do not use it as a generic 'write better code' rule. Scope is this domain only.

Example workflow

1. Install the Engineering Kit so .cursor/skills/realtime-websockets lands in the repo.
2. Open a new Cursor agent chat pointed at the files this skill governs.
3. Ask the Realtime Systems Lead (realtime-engineer) to read the skill, or run /realtime-feature: WebSockets & Realtime State Synchronizer.
4. Review the first artifact against the practices below. If it violates one, stop and correct the file. Do not prompt 'just finish it'.
5. Commit the skill-guided files with the rest of the slice so the next session inherits the same standard.

Example usage

Example prompt: "Read .cursor/skills/realtime-websockets and apply it to this change. Do not invent extra conventions."

Or trigger the pipeline: /realtime-feature: WebSockets & Realtime State Synchronizer. That command is written to load this skill.

Check the output against: Use Server-Sent Events (SSE) for one-way streaming (like LLM outputs) to reduce overhead

Example output

• The skill itself does not write a single output file. It changes what the agent is allowed to produce in code, schema, and tests.
• When you run /realtime-feature: WebSockets & Realtime State Synchronizer, expect repo files plus notes under docs/, not a chat-only answer.

Best practices

• Use Server-Sent Events (SSE) for one-way streaming (like LLM outputs) to reduce overhead
• Implement exponential backoff reconnect strategies for client WebSocket connections
• Authenticate WebSocket handshakes via short-lived auth tokens
• Broadcast channel messages efficiently through Redis Pub/Sub backplanes

Common mistakes

• Ignoring "Use Server-Sent Events (SSE) for one-way streaming (like LLM outputs) to reduce overhead" and hoping a later prompt will clean it up.
• Copying the skill into .cursor/rules as always-on. That burns context and fights Cursor's load-on-match design.
• Running two overlapping skills that contradict each other in the same turn.
• Letting the agent skip tests or types because 'the skill is about architecture'.