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Tools: I Made Claude Code Auto-Fix Breaking API Changes in CI How

2026-03-27 0 views admin
Tools: I Made Claude Code Auto-Fix Breaking API Changes in CI How

The Problem

The Solution: Delimit GitHub Action

The Auto-Fix Loop

The Loop in Practice

CLI for Local Development

Custom Policies

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MIT licensed. No API keys or external services required. AI coding assistants are great at generating code. But what happens when the code they generate breaks your API contract? I built a workflow where Claude Code reads structured CI output, understands the breaking change, and fixes it — automatically. If you have an OpenAPI spec checked into your repo, there's a good chance nobody is actually reviewing it on pull requests. Linters like Spectral validate the spec in isolation, but they don't compare old vs. new. They'll catch a missing description, but not the fact that you just changed a response field from string to integer — the kind of change that breaks every downstream consumer. I needed something that would: I built Delimit, a GitHub Action that does all of this deterministically. No LLM in the loop, no external API calls — just a diff engine that understands 27 types of OpenAPI contract changes (17 breaking, 10 non-breaking). Add one workflow file to your repo: That's it. Delimit auto-fetches the base branch version of your spec and diffs it against the PR changes. It runs in advisory mode by default — posts a PR comment but never fails your build. Here's where it gets interesting. Claude Code can read CI output. So when Delimit flags a breaking change, Claude sees: That structured output is enough for Claude to submit a fix. You can see this working end-to-end on PR #11: The reason this converges (instead of looping forever) is that the diff engine is deterministic. Same input, same output. Templates let you quickly answer FAQs or store snippets for re-use. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse

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name: API Contract Check on: pull_request jobs: delimit: runs-on: ubuntu-latest permissions: pull-requests: write steps: - uses: actions/checkout@v4 - uses: delimit-ai/delimit-action@v1 with: spec: api/openapi.yaml name: API Contract Check on: pull_request jobs: delimit: runs-on: ubuntu-latest permissions: pull-requests: write steps: - uses: actions/checkout@v4 - uses: delimit-ai/delimit-action@v1 with: spec: api/openapi.yaml name: API Contract Check on: pull_request jobs: delimit: runs-on: ubuntu-latest permissions: pull-requests: write steps: - uses: actions/checkout@v4 - uses: delimit-ai/delimit-action@v1 with: spec: api/openapi.yaml npx delimit-cli lint api/openapi.yaml npx delimit-cli diff api/openapi.yaml --base main npx delimit-cli lint api/openapi.yaml npx delimit-cli diff api/openapi.yaml --base main npx delimit-cli lint api/openapi.yaml npx delimit-cli diff api/openapi.yaml --base main # .delimit/policies.yml rules: - id: no-v2-removals change_type: endpoint_removed path_pattern: "/v2/*" severity: error message: "v2 endpoints cannot be removed without a deprecation period" # .delimit/policies.yml rules: - id: no-v2-removals change_type: endpoint_removed path_pattern: "/v2/*" severity: error message: "v2 endpoints cannot be removed without a deprecation period" # .delimit/policies.yml rules: - id: no-v2-removals change_type: endpoint_removed path_pattern: "/v2/*" severity: error message: "v2 endpoints cannot be removed without a deprecation period" npx delimit-cli setup npx delimit-cli setup npx delimit-cli setup - Diff the spec against the base branch on every PR - Classify each change as breaking or non-breaking - Tell me the exact semver impact - Give me a migration guide so I could fix it fast - What changed (endpoint removed, type changed, enum value removed) - Where it changed (exact path in the spec) - Why it's breaking (severity classification) - How to fix it (migration guide) - Claude Code makes changes that modify the OpenAPI spec - Delimit runs and flags the breaking changes in a PR comment - Claude reads the comment, understands the issue, and pushes a fix - Delimit re-runs — all checks pass - GitHub Action: marketplace/actions/delimit-api-governance - Live PR demo: delimit-ai/delimit-mcp-server/pull/11 - Source: github.com/delimit-ai/delimit-mcp-server

🏷️ Tags

toolsutilitiessecurity toolsclaudebreakingchangesproblemsolution

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