Agent skill

Customerio Local Dev Loop

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

Configure Customer.io local development workflow. An agent skill from jeremylongshore/tons-of-skills-marketplace.

MITAuto-check: notesTesting & QA

Install Customerio Local Dev Loop

skills CLI
$ npx skills add jeremylongshore/tons-of-skills-marketplace --skill customerio-local-dev-loop -a claude-code

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

GitHub CLI
$ gh skill install jeremylongshore/tons-of-skills-marketplace customerio-local-dev-loop --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/customerio-local-dev-loop .claude/skills/customerio-local-dev-loop && 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
customerio-local-dev-loop
GitHub stars
2.8k
Token cost
~2.1k tokens
SKILL.md length
253 words
Files
2 (incl. references)
Skills in repo
3,342
Repo updated
First seen
Licence
MIT

At a glance

Configure Customer.io local development workflow. An agent skill from jeremylongshore/tons-of-skills-marketplace.

  • Works in 5 steps: Environment Configuration → Environment-Aware Client → Test Mocks for Unit Tests → …
  • Setting up local testing
  • SKILL.md covers Output, Examples, Overview and Prerequisites, plus 5 more sections
  • Calls npx; needs CUSTOMERIO_TRACK_API_KEY and CUSTOMERIO_APP_API_KEY

What it does

Customerio Local Dev Loop is an agent skill from jeremylongshore/tons-of-skills-marketplace. Configure Customer.io local development workflow. Use when setting up local testing, dev/staging isolation, or mocking Customer.io for unit tests. Trigger: "customer.io local dev", "test customer.io locally", "customer.io dev environment", "customer.io sandbox", "mock customer.io".

Its SKILL.md is about 2.1k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/implementation-guide.md`). Compatibility notes: Designed for Claude Code

It sits in Testing & QA, covering Unit testing. 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

  • Setting up local testing
  • Dev/staging isolation
  • Mocking Customer.io for unit tests

Example prompts

  • “customer.io local dev”
  • “test customer.io locally”
  • “customer.io dev environment”
  • “/customerio-local-dev-loop”

Requirements

  • Node.js
  • A credential in CUSTOMERIO_TRACK_API_KEY
  • A credential in CUSTOMERIO_APP_API_KEY
  • Compatibility (from SKILL.md): Designed for Claude Code
  • Pre-approved tools (allowed-tools): Read, Write, Edit, Bash(npm:*), Bash(npx:*), Glob, Grep

Workflow steps

5 steps, taken from the step headings in SKILL.md.

  1. Environment Configuration
  2. Environment-Aware Client
  3. Test Mocks for Unit Tests
  4. Integration Test with Real API
  5. Dev Scripts

What it can do on your machine

Read from SKILL.md and the folder at commit 80f86df. 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
    • Bash(npm:*)
    • Bash(npx:*)
    • Glob
    • Grep

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • npx

    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):

    • docs.customer.io
    • github.com

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

  • Credentials

    Names these keys or tokens, usually read from environment variables:

    • CUSTOMERIO_TRACK_API_KEY
    • CUSTOMERIO_APP_API_KEY

    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

Customerio Local Dev Loop loads about 2.1k tokens when it runs, and up to ~3.1k if it reads all its reference files. Until then it costs about 77 tokens; SKILL.md has 253 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~77
When it runs · the whole SKILL.md, loaded when a task matches
~2.1k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~3.1k

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: notes

The automated check noted patterns worth knowing about, such as sudo or a known installer.

  • NoteMentions a .env fileSKILL.md:52
    # .env.development
  • NoteMentions a .env fileSKILL.md:60
    # .env.test
  • NoteMentions a .env fileSKILL.md:232
    npx dotenv -e .env.development -- npx vitest run tests/customerio.integration.test.ts
  • NoteMentions a .env fileSKILL.md:241
    "cio:verify": "dotenv -e .env.development -- tsx scripts/verify-customerio.ts",
  • NoteMentions a .env fileSKILL.md:242
    "cio:test": "dotenv -e .env.development -- vitest run tests/customerio.integration.test.ts",
  • NoteMentions a .env fileSKILL.md:261
    | Dev events in production | Wrong `.env` file loaded | Verify `NODE_ENV` and env file path |

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 80f86df, republished under its MIT licence (© jeremylongshore). 253 words, ~2,065 tokens.

Download SKILL.mdSave it as .claude/skills/customerio-local-dev-loop/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
customerio-local-dev-loop
description
Configure Customer.io local development workflow. Use when setting up local testing, dev/staging isolation, or mocking Customer.io for unit tests. Trigger: "customer.io local dev", "test customer.io locally", "customer.io dev environment", "customer.io sandbox", "mock customer.io".
allowed-tools
Read, Write, Edit, Bash(npm:*), Bash(npx:*), Glob, Grep
compatibility
Designed for Claude Code
version
1.14.0
license
MIT
author
Jeremy Longshore <jeremy@intentsolutions.io>
tags
saas, customer-io, testing, development, workflow

Customer.io Local Dev Loop

Output

  • A small, test-backed local change using a non-production workspace and synthetic recipient data.
  • A reviewed deployment/revert path that preserves production campaigns, consent, and contact data.

Examples

Use a development workspace and a synthetic profile such as test-user-001; validate the event schema locally, run the focused test, and inspect the resulting campaign behavior before committing. Never point local experiments at production segments or use real recipient data to debug a template.

Overview

Set up an efficient local development workflow for Customer.io: environment isolation via separate workspaces, a dry-run client for safe development, test mocks for unit tests, and prefixed events that never pollute production data.

Prerequisites

  • customerio-node installed
  • Separate Customer.io workspace for development (recommended — free workspaces available)
  • dotenv or similar for environment variable loading

Instructions

Step 1: Environment Configuration
bash
# .env.development
CUSTOMERIO_SITE_ID=dev-site-id
CUSTOMERIO_TRACK_API_KEY=dev-track-key
CUSTOMERIO_APP_API_KEY=dev-app-key
CUSTOMERIO_REGION=us
CUSTOMERIO_DRY_RUN=false
CUSTOMERIO_EVENT_PREFIX=dev_

# .env.test
CUSTOMERIO_SITE_ID=not-needed
CUSTOMERIO_TRACK_API_KEY=not-needed
CUSTOMERIO_APP_API_KEY=not-needed
CUSTOMERIO_DRY_RUN=true
CUSTOMERIO_EVENT_PREFIX=test_
Step 2: Environment-Aware Client
typescript
// lib/customerio-dev.ts
import { TrackClient, APIClient, RegionUS, RegionEU } from "customerio-node";

interface CioConfig {
  siteId: string;
  trackApiKey: string;
  appApiKey: string;
  region: typeof RegionUS | typeof RegionEU;
  dryRun: boolean;
  eventPrefix: string;
}

function loadConfig(): CioConfig {
  return {
    siteId: process.env.CUSTOMERIO_SITE_ID ?? "",
    trackApiKey: process.env.CUSTOMERIO_TRACK_API_KEY ?? "",
    appApiKey: process.env.CUSTOMERIO_APP_API_KEY ?? "",
    region: process.env.CUSTOMERIO_REGION === "eu" ? RegionEU : RegionUS,
    dryRun: process.env.CUSTOMERIO_DRY_RUN === "true",
    eventPrefix: process.env.CUSTOMERIO_EVENT_PREFIX ?? "",
  };
}

export class DevTrackClient {
  private client: TrackClient | null = null;
  private config: CioConfig;
  private log: typeof console.log;

  constructor() {
    this.config = loadConfig();
    this.log = console.log.bind(console);
    if (!this.config.dryRun) {
      this.client = new TrackClient(
        this.config.siteId,
        this.config.trackApiKey,
        { region: this.config.region }
      );
    }
  }

  async identify(userId: string, attributes: Record<string, any>) {
    const prefixedId = `${this.config.eventPrefix}${userId}`;
    if (this.config.dryRun) {
      this.log("[DRY RUN] identify:", prefixedId, attributes);
      return;
    }
    return this.client!.identify(prefixedId, attributes);
  }

  async track(userId: string, eventName: string, data?: Record<string, any>) {
    const prefixedId = `${this.config.eventPrefix}${userId}`;
    const prefixedEvent = `${this.config.eventPrefix}${eventName}`;
    if (this.config.dryRun) {
      this.log("[DRY RUN] track:", prefixedId, prefixedEvent, data);
      return;
    }
    return this.client!.track(prefixedId, {
      name: prefixedEvent,
      data,
    });
  }

  async suppress(userId: string) {
    const prefixedId = `${this.config.eventPrefix}${userId}`;
    if (this.config.dryRun) {
      this.log("[DRY RUN] suppress:", prefixedId);
      return;
    }
    return this.client!.suppress(prefixedId);
  }
}
Step 3: Test Mocks for Unit Tests
typescript
// __mocks__/customerio-node.ts (for vitest/jest auto-mocking)
import { vi } from "vitest";

export const TrackClient = vi.fn().mockImplementation(() => ({
  identify: vi.fn().mockResolvedValue(undefined),
  track: vi.fn().mockResolvedValue(undefined),
  trackAnonymous: vi.fn().mockResolvedValue(undefined),
  suppress: vi.fn().mockResolvedValue(undefined),
  destroy: vi.fn().mockResolvedValue(undefined),
  mergeCustomers: vi.fn().mockResolvedValue(undefined),
}));

export const APIClient = vi.fn().mockImplementation(() => ({
  sendEmail: vi.fn().mockResolvedValue({ delivery_id: "mock-delivery-123" }),
  sendPush: vi.fn().mockResolvedValue({ delivery_id: "mock-push-456" }),
  triggerBroadcast: vi.fn().mockResolvedValue(undefined),
}));

export const RegionUS = "us";
export const RegionEU = "eu";
export const SendEmailRequest = vi.fn().mockImplementation((data) => data);
export const SendPushRequest = vi.fn().mockImplementation((data) => data);
Step 4: Integration Test with Real API
typescript
// tests/customerio.integration.test.ts
import { describe, it, expect, afterAll } from "vitest";
import { TrackClient, RegionUS } from "customerio-node";

const TEST_PREFIX = `test_${Date.now()}_`;
const testUserIds: string[] = [];

const cio = new TrackClient(
  process.env.CUSTOMERIO_SITE_ID!,
  process.env.CUSTOMERIO_TRACK_API_KEY!,
  { region: RegionUS }
);

function testUserId(label: string): string {
  const id = `${TEST_PREFIX}${label}`;
  testUserIds.push(id);
  return id;
}

describe("Customer.io Integration", () => {
  afterAll(async () => {
    // Clean up all test users
    for (const id of testUserIds) {
      await cio.suppress(id).catch(() => {});
      await cio.destroy(id).catch(() => {});
    }
  });

  it("should identify a user", async () => {
    const id = testUserId("identify");
    await expect(
      cio.identify(id, { email: `${id}@test.example.com` })
    ).resolves.not.toThrow();
  });

  it("should track an event", async () => {
    const id = testUserId("track");
    await cio.identify(id, { email: `${id}@test.example.com` });
    await expect(
      cio.track(id, { name: "test_event", data: { step: 1 } })
    ).resolves.not.toThrow();
  });

  it("should reject invalid credentials", async () => {
    const badClient = new TrackClient("bad-id", "bad-key", {
      region: RegionUS,
    });
    await expect(
      badClient.identify("x", { email: "x@test.com" })
    ).rejects.toThrow();
  });
});

Run integration tests only against your dev workspace:

bash
# Load dev env and run integration tests
npx dotenv -e .env.development -- npx vitest run tests/customerio.integration.test.ts
Step 5: Dev Scripts
json
// package.json scripts
{
  "scripts": {
    "cio:verify": "dotenv -e .env.development -- tsx scripts/verify-customerio.ts",
    "cio:test": "dotenv -e .env.development -- vitest run tests/customerio.integration.test.ts",
    "cio:test:dry": "CUSTOMERIO_DRY_RUN=true vitest run tests/customerio"
  }
}

Workspace Isolation Strategy

EnvironmentWorkspace NameEvent PrefixDry Run
Unit tests(mocked)test_true
Integration testsmyapp-devinttest_false
Stagingmyapp-staging(none)false
Productionmyapp-prod(none)false

Error Handling

ErrorCauseSolution
Dev events in productionWrong .env file loadedVerify NODE_ENV and env file path
Mock not interceptingImport order issueMock customerio-node before importing your client module
Test user pollutionNo cleanupAlways suppress + destroy test users in afterAll

Resources

Next Steps

After setting up local dev, proceed to customerio-sdk-patterns for production-ready patterns.

© 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 1 other file (references) in skills/.curated/customerio-local-dev-loop of jeremylongshore/tons-of-skills-marketplace.

  • SKILL.md
  • references/implementation-guide.md

Open the folder on GitHubat commit 80f86df

Compare with similar skills

Customerio Local Dev Loop next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Customerio Local Dev Loop compared with similar skills
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Testing OpenLogi UIAprilNEA/OpenLogi23k—~1.1kAutomated safety check: PassApache-2.0
Go Testingcxuu/golang-skills1721 repos~1.3kAutomated safety check: PassApache-2.0
Contractssamchon/nestia2.2k—~1.3kAutomated safety check: PassMIT
Cohesion Over TestabilityEpicenterHQ/epicenter4.8k—~2kAutomated safety check: PassCustom licence

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Categories

Questions about Customerio Local Dev Loop

What does Customerio Local Dev Loop do?

Configure Customer.io local development workflow. An agent skill from jeremylongshore/tons-of-skills-marketplace. Customerio Local Dev Loop is an agent skill from jeremylongshore/tons-of-skills-marketplace.io local development workflow.

When should I use Customerio Local Dev Loop?

Customerio Local Dev Loop fits situations like: setting up local testing; dev/staging isolation; mocking Customer.io for unit tests.

How do I install Customerio Local Dev Loop in Claude Code?

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

How do I install Customerio Local Dev Loop in Codex?

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

Can I use Customerio Local Dev Loop 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 customerio-local-dev-loop -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/customerio-local-dev-loop, .gemini/skills/customerio-local-dev-loop, .github/skills/customerio-local-dev-loop and .opencode/skills/customerio-local-dev-loop in your project.

What does Customerio Local Dev Loop need to run?

Going by SKILL.md and its folder, Customerio Local Dev Loop needs the command-line tools its instructions call (npx) and credentials named CUSTOMERIO_TRACK_API_KEY and CUSTOMERIO_APP_API_KEY. Our summary lists: Node.js; A credential in CUSTOMERIO_TRACK_API_KEY; A credential in CUSTOMERIO_APP_API_KEY. Its frontmatter pre-approves these tools: Read, Write, Edit, Bash(npm:*), Bash(npx:*), Glob, Grep. Compatibility (from SKILL.md): Designed for Claude Code.

Does Customerio Local Dev Loop access the network?

SKILL.md names 2 domains. As links in the text: docs.customer.io and github.com. This is read from the text; nothing was executed.

Is Customerio Local Dev Loop safe to install?

Our automated static check of SKILL.md found notes only (mentions a .env file), nothing it rates as a warning. It is not a guarantee. Review the folder before installing.

What licence does Customerio Local Dev Loop use?

Customerio Local Dev Loop 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 Customerio Local Dev Loop use?

About 2.1k tokens (SKILL.md is roughly 8.3k 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 991 tokens, read only when the agent opens those files.

What are the alternatives to Customerio Local Dev Loop?

Skills that share tags, products or a category with Customerio Local Dev Loop: TDD Workflow (hellangleZ/burn-in-cceverywhere-ralph, 112 stars), Testing OpenLogi UI (AprilNEA/OpenLogi, 23k stars), Go Testing (cxuu/golang-skills, 172 stars) and Contracts (samchon/nestia, 2.2k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Customerio Local Dev Loop?

jeremylongshore (a GitHub user) maintains it in jeremylongshore/tons-of-skills-marketplace, which has 2,825 GitHub stars. The repository holds 3,342 skills in this directory. The repository was last updated on October 9, 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.