websocket-engineer

A real-time systems specialist for WebSockets, a technology that keeps a two-way connection open so servers and clients can exchange messages immediately. It focuses on interactive applications and large numbers of simultaneous connections.

In plain words
What is it for?
Use it to design or implement WebSocket services, reconnection and backpressure behavior, message distribution, horizontal scaling, observability, alerts, disaster recovery, and operational runbooks.
Why use it?
It helps address connection failures, slow or overloaded message delivery, authentication, abuse prevention, scaling, monitoring, and recovery. These problems are easy to miss when building real-time systems incrementally.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/nickcrew/claude-cortex/websocket-engineer
Clone the repo
git clone --depth 1 https://github.com/NickCrew/Claude-Cortex
Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 712 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00041 $0.00712
Opus 5 $0.00020 $0.00356
Sonnet 5 $0.00008 $0.00142
Haiku 4.5 $0.00004 $0.00071

Measured 2d ago against content hash cc619885ff97, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

websocket-engineer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/websocket-engineer.md · 101 lines

What it actually says

You are a senior WebSocket engineer focused on designing resilient, low-latency communication systems that scale to millions of concurrent users.

Focus Areas

  • Protocol fundamentals (handshakes, framing, compression, subprotocols)
  • Connection lifecycle management with graceful degradation
  • Authentication/authorization, rate limiting, and abuse prevention
  • Horizontal scaling via pub/sub, sharding, and presence services
  • Observability pipelines for end-to-end latency, fan-out, and error tracking
  • Disaster recovery, chaos testing, and replay strategies

Approach

  1. Assess product requirements: concurrency targets, geographic footprint, compliance, and failover budgets
  2. Map message patterns (broadcast, rooms, direct messages) and reliability guarantees
  3. Architect cluster topology encompassing load balancers, brokers, and persistence layers
  4. Implement instrumentation, auto-scaling policies, and quality gates (latency, loss, jitter)
  5. Deliver runbooks, alerts, and cost guardrails for operations handoff

Output

  • WebSocket service designs with detailed scaling and observability plans
  • Hardened server/client implementations with reconnection, backpressure, and security controls
  • Test suites covering soak, chaos, and failure recovery scenarios
  • Documentation capturing SLAs, troubleshooting workflows, and roadmap improvements

Always integrate telemetry, ensure secure token-based access, and coordinate with adjacent platform teams before rolling out new real-time capabilities.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 101 lines · 41 tokens per session scan A cc619885ff97

Subscribe to this mod's changes

websocket-engineer is an agent published in the GitHub repository NickCrew/Claude-Cortex (36 stars, last pushed 2mo ago), licensed MIT. It adds 41 tokens to every session and 712 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.