Skip to content
Get packs

API Breaking Change Detector

Checks C# API changes against TypeScript/JavaScript frontend code to catch broken contracts

Source Download skill
Repository
github/awesome-copilot
Stars
40,703
Licence
MIT
Files
1 file

What it does

When you change a C# Web API controller or data transfer object, this skill makes the AI agent read the matching frontend or client code (React, Angular, Vue, Svelte, Node.js, Fetch, Axios, NSwag-generated clients) and look for mismatches in both directions. It flags backend changes that would break the app, such as renamed or removed JSON fields, new required parameters, or status codes the client does not handle, and it also flags frontend code that sends fields the backend ignores or reads fields the backend no longer returns. It reports findings without changing any code.

Great for

  • Backend developers on ASP.NET Core teams who want to check a DTO or controller change before merging
  • Full-stack teams that keep a C# API and a TypeScript frontend in the same codebase
  • Engineers preparing a release who want an audit of the API surface against its consumers

Skip it if

  • Projects without C# Web API backends, since the skill is written specifically for C# controllers and DTOs (wrong stack, no useful output)
  • Comparing two exported OpenAPI spec files, which the skill explicitly does not do (use a spec diff tool instead)
  • Generating or scaffolding new API code, which is covered by other skills; this one only audits existing code

Try asking

  • “Check whether my change to the UserDto in UsersController will break the React client in the web folder”
  • “Audit the orders endpoints against their Angular consumers before I merge this pull request”
  • “Verify that our NSwag generated client is still in sync with the backend controllers”
  • “Find frontend code that reads response fields the backend no longer returns”
Step-by-step guide: how to use API Breaking Change DetectorInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 1 original files, the MIT licence and an attribution note.

    api-breaking-change-detector.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip api-breaking-change-detector.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip api-breaking-change-detector.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Name the specific controller or DTO you changed so the agent audits a focused scope instead of the whole API
  • Make sure Program.cs is in the repository so the agent can detect global camelCase JSON settings, which affect how field names are matched
  • Treat the 'No consumer located' section as a to-do list for manual review, since static search can miss dynamically built URLs

What's inside

  • SKILL.md

Redistributed unmodified from github/awesome-copilot under the MIT licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.