chore: changeset validating github action

.github/workflows/validate-pr-base.yml

@@ -0,0 +1,20 @@
+name: Validate PRs
+
+on:
+  pull_request:
+    types:
+      - opened
+      - reopened
+      - synchronize
+      - edited
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/github-script@v7
+        with:
+          script: |
+            const { validate } = await import('${{ github.workspace }}/scripts/validate-prs.js');
+            await validate({ context });

scripts/validate-prs.js

@@ -0,0 +1,43 @@
+/* eslint-env node */
+import read from '@changesets/read';
+import conventionalCommitsParser from 'conventional-commits-parser';
+
+export async function validate({ context }) {
+  const { base, title, auto_merge: autoMerge } = context.payload.pull_request;
+
+  if (base.startsWith('staging/')) {
+    return true;
+  }
+
+  const { type } = conventionalCommitsParser.sync(title);
+
+  console.log({ type });
+
+  if (autoMerge?.merge_method === 'rebase') {
+    throw new Error('Validating auto-rebase PRs is not yet implemented');
+    // one approach could be to use `@commitlint/load` to read { from: baseBranch }
+    // then pipe that array as a stream to conventionalcommitsparser's transform stream
+  }
+
+  const sets = await read(process.cwd());
+
+  const release = sets.reduce((greatest, type) => {
+    switch (greatest) {
+      case null:
+      case 'major':
+        return greatest;
+      case 'minor':
+        return type === 'major' ? type : greatest;
+      case 'patch':
+        return (type === 'major' || type === 'minor') ? type : greatest;
+    }
+  }, null);
+
+  if (!release && type) {
+    throw new Error(`PR conventional commit title has type (${type}) but no changesets were detected.`);
+  }
+
+  if (type !== release) {
+    throw new Error(`PR conventional commit title type (${type}) does not match release type (${release}).`);
+  }
+}