serverless-patterns

serverless-patterns is a skill for Claude Code, Codex from cosmicstack-labs/mercury-agent-skills. It costs 21 tokens per session (515 once invoked), scanned A, original, MIT.

A guide to building applications from small cloud functions that run in response to requests or events, without managing servers directly. It covers AWS Lambda, API Gateway, queues, retries, and cold starts—the delay before an unused function starts running.

In plain words
What is it for?
Use it to design event-driven functions, queued background processing, request validation, caching, rate limiting, and functions that can safely run more than once.
Why use it?
It helps separate services, handle bursts of work, retry failures, and reduce delays or unnecessary cost in serverless applications.

Skill for Claude CodeCodex

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 skills/cosmicstack-labs/mercury-agent-skills/serverless-patterns
Any agent
npx skills add cosmicstack-labs/mercury-agent-skills --skill serverless-patterns
Clone the repo
git clone --depth 1 https://github.com/cosmicstack-labs/mercury-agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for serverless-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/cosmicstack-labs/mercury-agent-skills/serverless-patterns.svg)](https://agentmods.dev/skills/cosmicstack-labs/mercury-agent-skills/serverless-patterns)
Your own site
<a href="https://agentmods.dev/skills/cosmicstack-labs/mercury-agent-skills/serverless-patterns"><img src="https://agentmods.dev/badge/skills/cosmicstack-labs/mercury-agent-skills/serverless-patterns.svg" alt="Measured on agentmods" height="20"></a>
Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 515 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 5.1 $0.00021 $0.00515
Opus 5 $0.00010 $0.00258
Sonnet 5 $0.00004 $0.00103
Haiku 4.5 $0.00002 $0.00052

Measured 6d ago against content hash 0dd40598e1c1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

serverless-patterns 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 6d 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.

categories/backend/serverless-patterns/SKILL.md · 69 lines

What it actually says

Serverless Patterns

Build scalable serverless applications.

Core Patterns

Function Design

  • Single responsibility per function
  • Stateless (use external storage for state)
  • Idempotent handlers (retry-safe)
  • Receive event, process, return/forward

Cold Start Mitigation

Strategy Effect Tradeoff
Provisioned Concurrency Zero cold starts Cost
Smaller runtime (Node/Python) Faster start Language choice
Keep-alive ping Reduce frequency Extra cost
Lambda SnapStart (Java) Fast restore State constraints
Lambda@Edge Regional distribution 1MB response limit

Event-Driven Design

Event Types

Events:
  - UserRegistered { userId, email, timestamp }
  - OrderPlaced { orderId, items, total }
  - PaymentProcessed { orderId, amount, status }
  - EmailSent { to, template, variables }

SQS + Lambda Pattern

API Gateway → Lambda (producer) → SQS → Lambda (consumer) → DynamoDB

Benefits: decoupling, buffering, retry, dead-letter queue.

API Gateway Patterns

  • Request validation at gateway level
  • Caching for GET endpoints (TTL per route)
  • WAF for rate limiting and IP blocks
  • Custom domain with ACM certificate
  • Usage plans for API keys

Frameworks

  • SAM (AWS) — YAML/YML, local testing
  • Serverless Framework — Multi-cloud, plugins
  • CDK (AWS) — Full programming languages
  • Terraform — If already using for other infra
  • Chalice (Python) — Flask-like, AWS only

Best Practices

  • Function timeout: max 30s for APIs, 15min for background
  • Memory: allocate more = more CPU (for compute-heavy, use 1.7GB+)
  • Monitor: Duration, Invocations, Error count, Throttles
  • Logs: structured JSON to CloudWatch
  • Security: least-privilege IAM roles per function
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. 6d ago First seen · 69 lines · 21 tokens per session scan A 0dd40598e1c1

Subscribe to this mod's changes

serverless-patterns is a skill published in the GitHub repository cosmicstack-labs/mercury-agent-skills (471 stars, last pushed 11d ago), licensed MIT. It adds 21 tokens to every session and 515 once invoked, about $0.0001 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.

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