api-no-breaking-changes

**Impact: CRITICAL**

calcom@calcom

GitHub

From plugin

caldiy

47k95 skills95 agents

Install

$ npx -y skills add calcom/cal.com --agent claude-code

How it fires

How this agent gets triggered: by you, by Claude, or both.

Fires itselfAuto-invocation. Claude auto-loads it when your prompt matches the work.
You can call itInvoke it directly when you want it.

Context preview

The summary Claude sees to decide when to auto-load this agent.

**Impact: CRITICAL**

Agent definition

api-no-breaking-changes.md

title: Never Introduce Breaking API Changes
impact: CRITICAL
impactDescription: Maintains developer trust and prevents integration nightmares
tags: api, stability, versioning, backwards-compatibility

Never Introduce Breaking API Changes

**Impact: CRITICAL**

Once an API endpoint is public, it must remain stable. Breaking changes destroy developer trust and create integration nightmares for our users.

**Strategies for avoiding breaking changes:**

Always add new fields as optional
Use API versioning when you must change existing behavior
Deprecate old endpoints gracefully with clear migration paths
Maintain backward compatibility for at least two major versions

**Incorrect (breaking change):**

// v1 - Original response
interface BookingResponse {
  id: number;
  startTime: string; // ISO string
}

// v1 - Breaking change: renamed field
interface BookingResponse {
  id: number;
  start: string; // Renamed from startTime - BREAKS CLIENTS
}

**Correct (non-breaking evolution):**

// v1 - Original response
interface BookingResponse {
  id: number;
  startTime: string;
}

// v1 - Non-breaking: add new field, keep old one
interface BookingResponse {
  id: number;
  startTime: string; // Keep for backwards compatibility
  start: string; // New preferred field
}

**When you must make breaking changes:**