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Agent skill

Emitting API Events

by jeremylongshore in jeremylongshore/tons-of-skills-marketplace

Build event-driven APIs with webhooks, Server-Sent Events, and real-time notifications.

MITAuto-check passedBackend & APIs

Install Emitting API Events

skills CLI
$ npx skills add jeremylongshore/tons-of-skills-marketplace --skill emitting-api-events -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install jeremylongshore/tons-of-skills-marketplace emitting-api-events --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/jeremylongshore/tons-of-skills-marketplace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/.curated/emitting-api-events .claude/skills/emitting-api-events && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
emitting-api-events
GitHub stars
2.8k
Token cost
~1.4k tokens
SKILL.md length
589 words
Files
4 (incl. references)
Skills in repo
3,342
Repo updated
First seen
Licence
MIT

At a glance

Build event-driven APIs with webhooks, Server-Sent Events, and real-time notifications.

  • Works in 8 steps: Identify event-producing operations… → Define event schemas for each event type… → Implement the event emitter service that… → …
  • Building event-driven API architectures
  • SKILL.md covers Overview, Prerequisites, Instructions and Output, plus 3 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Emitting API Events is an agent skill from jeremylongshore/tons-of-skills-marketplace. Build event-driven APIs with webhooks, Server-Sent Events, and real-time notifications. Use when building event-driven API architectures. Trigger with phrases like "add webhooks", "implement events", or "create event-driven API".

Its SKILL.md is about 1.4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files, including reference files (for example `references/errors.md`, `references/examples.md` and `references/implementation.md`). Compatibility notes: Designed for Claude Code

It sits in Backend & APIs, covering Event-driven systems, Webhooks and Realtime and WebSockets. The repository describes itself as: Model-agnostic agent-skills platform with a harness-free canonical layer, verified adapters, and the ccpi package manager. Explore at tonsofskills.com. The licence is MIT.

When your agent uses it

  • Building event-driven API architectures
  • With phrases like add webhooks
  • Implement events
  • Create event-driven API

Example prompts

  • “add webhooks”
  • “implement events”
  • “create event-driven API”
  • “/emitting-api-events”

Requirements

  • Compatibility (from SKILL.md): Designed for Claude Code
  • Pre-approved tools (allowed-tools): Read, Write, Edit, Grep, Glob, Bash(api:events-*)

Workflow steps

8 steps, taken from the first numbered list in SKILL.md.

  1. Identify event-producing operations using Grep and Read, cataloging every API mutation (POST, PUT, PATCH, DELETE) that should emit events…
  2. Define event schemas for each event type with versioning: include eventId (UUID), eventType, version, timestamp (ISO 8601), source…
  3. Implement the event emitter service that publishes events to the message broker after successful API mutations, using the transactional…
  4. Build a webhook subscription management API: POST /webhooks (subscribe), GET /webhooks (list), DELETE /webhooks/:id (unsubscribe), with…
  5. Implement webhook delivery with HMAC-SHA256 signed payloads, configurable retry policy (exponential backoff: 1min, 5min, 30min, 2hr…
  6. Add Server-Sent Events endpoint (GET /events/stream) for real-time event delivery to browser clients, with Last-Event-ID support for…
  7. Create a dead-letter queue for events that exhaust all delivery retry attempts, with alerting and manual replay capability.
  8. Write integration tests covering event emission, webhook delivery with signature verification, SSE stream connection with reconnection…

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Write
    • Edit
    • Grep
    • Glob
    • Bash(api:events-*)

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • cloudevents.io
    • developer.mozilla.org

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    Designed for Claude Code

    From compatibility in the SKILL.md frontmatter.

Context cost

Emitting API Events loads about 1.4k tokens when it runs, and up to ~3.5k if it reads all its reference files. Until then it costs about 62 tokens; SKILL.md has 589 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~62
When it runs · the whole SKILL.md, loaded when a task matches
~1.4k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~3.5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 589 words, ~1,441 tokens.

Download SKILL.mdSave it as .claude/skills/emitting-api-events/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.
name
emitting-api-events
description
Build event-driven APIs with webhooks, Server-Sent Events, and real-time notifications. Use when building event-driven API architectures. Trigger with phrases like "add webhooks", "implement events", or "create event-driven API".
allowed-tools
Read, Write, Edit, Grep, Glob, Bash(api:events-*)
compatibility
Designed for Claude Code
version
1.24.0
author
Jeremy Longshore <jeremy@intentsolutions.io>
license
MIT
tags
api, webhooks, emitting-api

Emitting API Events

Overview

Build event-driven API architectures using outbound webhooks, Server-Sent Events (SSE), and message broker integration. Implement event emission from API mutations, event schema registry, subscriber management, delivery guarantees with retry logic, and event sourcing patterns for maintaining a complete audit log of API state changes.

Prerequisites

  • Message broker: Redis Pub/Sub, RabbitMQ, Apache Kafka, or AWS SNS/SQS
  • Persistent storage for event log and subscriber registrations (PostgreSQL, MongoDB)
  • Webhook delivery infrastructure with retry queue (Bull, Celery, or managed service)
  • Event schema registry for versioned event type definitions
  • SSE-capable web framework for real-time event streaming to browser clients

Instructions

  1. Identify event-producing operations using Grep and Read, cataloging every API mutation (POST, PUT, PATCH, DELETE) that should emit events, with event type names following resource.action convention (e.g., order.created, user.updated).
  2. Define event schemas for each event type with versioning: include eventId (UUID), eventType, version, timestamp (ISO 8601), source (service identifier), and data (type-specific payload).
  3. Implement the event emitter service that publishes events to the message broker after successful API mutations, using the transactional outbox pattern to ensure events are not lost on application crash.
  4. Build a webhook subscription management API: POST /webhooks (subscribe), GET /webhooks (list), DELETE /webhooks/:id (unsubscribe), with URL validation, event type filtering, and signing secret generation.
  5. Implement webhook delivery with HMAC-SHA256 signed payloads, configurable retry policy (exponential backoff: 1min, 5min, 30min, 2hr, 24hr), and automatic subscription deactivation after consecutive failures.
  6. Add Server-Sent Events endpoint (GET /events/stream) for real-time event delivery to browser clients, with Last-Event-ID support for reconnection and missed event replay.
  7. Create a dead-letter queue for events that exhaust all delivery retry attempts, with alerting and manual replay capability.
  8. Write integration tests covering event emission, webhook delivery with signature verification, SSE stream connection with reconnection, and dead-letter queue behavior.

See ${CLAUDE_SKILL_DIR}/references/implementation.md for the full implementation guide.

Output

  • ${CLAUDE_SKILL_DIR}/src/events/emitter.js - Event emission service with outbox pattern
  • ${CLAUDE_SKILL_DIR}/src/events/schemas/ - Versioned event type schema definitions
  • ${CLAUDE_SKILL_DIR}/src/events/webhooks/ - Webhook delivery, signing, and retry logic
  • ${CLAUDE_SKILL_DIR}/src/events/sse.js - Server-Sent Events streaming endpoint
  • ${CLAUDE_SKILL_DIR}/src/routes/webhooks.js - Webhook subscription management API
  • ${CLAUDE_SKILL_DIR}/src/events/dead-letter.js - Dead-letter queue handler with replay
  • ${CLAUDE_SKILL_DIR}/tests/events/ - Event emission and delivery integration tests
Show full SKILL.md (239 more words)Show less

Error Handling

ErrorCauseSolution
Event lost on crashApplication crashes between database commit and event publishUse transactional outbox pattern: write event to outbox table in same transaction, poll and publish separately
Webhook delivery failureSubscriber endpoint unreachable or returns non-2xxRetry with exponential backoff; deactivate subscription after 5 consecutive failures; notify subscriber admin
Event ordering violationConcurrent mutations publish events out of orderUse partition keys (resource ID) for ordered delivery within a partition; accept out-of-order across partitions
SSE connection memory leakServer accumulates stale SSE connections without cleanupImplement heartbeat comments (:keepalive\n\n) every 15 seconds; detect and close dead connections
Schema version mismatchConsumer expects v1 event format but receives v2Include version field in event envelope; support simultaneous v1/v2 delivery; deprecate old versions with notice

Refer to ${CLAUDE_SKILL_DIR}/references/errors.md for comprehensive error patterns.

Examples

Order lifecycle events: Emit order.created, order.payment_received, order.shipped, and order.delivered events with order details, enabling downstream services (warehouse, email, analytics) to react asynchronously.

SSE live notifications: Browser client connects to GET /events/stream?types=message.received,order.updated and receives real-time event updates with automatic reconnection and Last-Event-ID replay on network interruption.

Transactional outbox: Write the event record to an outbox table within the same database transaction as the API mutation, then poll the outbox table every 100ms to publish events to Kafka, ensuring at-least-once delivery.

See ${CLAUDE_SKILL_DIR}/references/examples.md for additional examples.

Resources

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (references) in skills/.curated/emitting-api-events of jeremylongshore/tons-of-skills-marketplace.

  • SKILL.md
  • references/errors.md
  • references/examples.md
  • references/implementation.md

Open the folder on GitHubat commit cfae287

Compare with similar skills

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Categories

Questions about Emitting API Events

What does Emitting API Events do?

Build event-driven APIs with webhooks, Server-Sent Events, and real-time notifications. Emitting API Events is an agent skill from jeremylongshore/tons-of-skills-marketplace. Build event-driven APIs with webhooks, Server-Sent Events, and real-time notifications.

When should I use Emitting API Events?

Emitting API Events fits situations like: building event-driven API architectures; with phrases like add webhooks; implement events; create event-driven API.

How do I install Emitting API Events in Claude Code?

Run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill emitting-api-events -a claude-code`. Or copy the skill folder (skills/.curated/emitting-api-events in jeremylongshore/tons-of-skills-marketplace) into .claude/skills/emitting-api-events in your project. Claude Code loads it when a task matches its description.

How do I install Emitting API Events in Codex?

Run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill emitting-api-events -a codex`. Or copy the skill folder (skills/.curated/emitting-api-events in jeremylongshore/tons-of-skills-marketplace) into .agents/skills/emitting-api-events in your project. Codex loads it when a task matches its description.

Can I use Emitting API Events in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill emitting-api-events -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/emitting-api-events, .gemini/skills/emitting-api-events, .github/skills/emitting-api-events and .opencode/skills/emitting-api-events in your project.

What does Emitting API Events need to run?

SKILL.md names no scripts, command-line tools or credentials: Emitting API Events is instructions for the agent only. Its frontmatter pre-approves these tools: Read, Write, Edit, Grep, Glob, Bash(api:events-*). Compatibility (from SKILL.md): Designed for Claude Code.

Does Emitting API Events access the network?

SKILL.md names 2 domains. As links in the text: cloudevents.io and developer.mozilla.org. This is read from the text; nothing was executed.

Is Emitting API Events safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Emitting API Events use?

Emitting API Events is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Emitting API Events use?

About 1.4k tokens (SKILL.md is roughly 5.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 2.1k tokens, read only when the agent opens those files.

What are the alternatives to Emitting API Events?

Skills that share tags, products or a category with Emitting API Events: Cryptofeed (2025Emma/vibe-coding-cn, 23k stars), Cb Realtime API (BlkLeg/CircuitBreaker, 201 stars), Adobe App Builder Action Scaffolder (adobe/skills, 197 stars) and Sanity Best Practices (sanity-io/agent-toolkit, 188 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Emitting API Events?

jeremylongshore (a GitHub user) maintains it in jeremylongshore/tons-of-skills-marketplace, which has 2,827 GitHub stars. The repository holds 3,342 skills in this directory. The repository was last updated on October 10, 2026.

Source: jeremylongshore/tons-of-skills-marketplace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.