chore(release): try changesets instead of changelog (#10138)

The newish changelog workflow has personally saved me a lot of time and
is half the reason we were able to release so many times on a moment's
notice last week. But it's prone to merge conflicts, both in this repo
and in the release tooling (most cherry picks from the main branch to
the next branch had merge conflicts because of the changelog) so it's
not going to scale out much more. But it's proved it's usefulness.

I tried Changesets proper—seemed like the obvious choice and @ahaywood
even independently came up with the idea—but it's overkill. I don't want
to have to associate a semver with a PR (we use milestones for that). I
also don't want to have to pick which packages we're versioning. Right
now it's always all of them. And without the tooling or without using
git, there's no obvious way to tie a changeset back to the PR that made
it. (Maybe one of the changeset changelog packages do this, but config.)
All I really want is what we're doing right now without the merge
conflicts, so I spiked on a small script to generate a minimal
changeset:

```
yarn changesets 10116
yarn changesets #10116
```

The idea is that we'll do what we've been doing, but just via that
command. It'll write a file to `.changesets/three-random-words.md`, and
we'll put our release notes for the PR there. The release tooling can
aggregate them into release notes at the time of release.

The main con is that we can't see all the unreleased changes in linear
order in one file. But tradeoffs. It's definitely worth not having to
put up with merge conflicts.

.github/actions/check_changesets/action.yml

@@ -0,0 +1,10 @@
+name: Check changesets
+description: Checks if changeset was added to the PR
+
+runs:
+  using: node20
+  main: check_changesets.mjs
+
+inputs:
+  labels:
+    required: true

.github/actions/check_changesets/check_changesets.mjs

@@ -0,0 +1,47 @@
+import { getInput } from '@actions/core'
+import { exec, getExecOutput } from '@actions/exec'
+import github from '@actions/github'
+
+async function main() {
+  // If the PR has the "changesets-ok" label, just pass.
+  const { labels } = JSON.parse(getInput('labels'))
+  const hasChangesetsOkLabel = labels.some((label) => label.name === 'changesets-ok')
+  if (hasChangesetsOkLabel) {
+    console.log('Skipping check because of the "changesets-ok" label')
+    return
+  }
+
+  // Check if the PR adds a changeset.
+  await exec('git fetch origin main', [], { silent: true })
+  const { stdout } = await getExecOutput('git diff origin/main --name-only', [], { silent: true })
+  const changedFiles = stdout.toString().trim().split('\n').filter(Boolean)
+  const addedChangeset = changedFiles.some((file) => file.startsWith('.changesets/'))
+  if (addedChangeset) {
+    // Empty space here (and in subsequent `console.log`s) for formatting in the action.
+    console.log(
+      [
+        '',
+        "Added a changeset",
+      ].join('\n')
+    )
+
+    return
+  }
+
+  const pr = github.context.payload.pull_request
+  console.log(
+    [
+      '',
+      '📝 Consider adding a changeset',
+      '==============================',
+      '',
+      'If this is a user-facing PR (a feature or a fix), it should probably have a changeset.',
+      `Run \`yarn changesets ${pr.number}\` to create a changeset for this PR.`,
+      "If it doesn't need one (it's a chore), you can add the 'changesets-ok' label.",
+    ].join('\n')
+  )
+
+  process.exitCode = 1
+}
+
+main()

.github/actions/check_changelog/package.json → .github/actions/check_changesets/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "check_changelog",
+  "name": "check_changesets",
   "private": true,
   "dependencies": {
     "@actions/core": "1.10.1",

.github/actions/check_changelog/yarn.lock → .github/actions/check_changesets/yarn.lock

@@ -171,9 +171,9 @@ __metadata:
   languageName: node
   linkType: hard
 
-"check_changelog@workspace:.":
+"check_changesets@workspace:.":
   version: 0.0.0-use.local
-  resolution: "check_changelog@workspace:."
+  resolution: "check_changesets@workspace:."
   dependencies:
     "@actions/core": "npm:1.10.1"
     "@actions/exec": "npm:1.1.1"

.github/workflows/check-changelog.yml

@@ -1,4 +1,4 @@
-name: 📝 Check CHANGELOG.md
+name: 📝 Check changesets
 
 on:
   pull_request:
@@ -11,8 +11,8 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  check-changelog:
-    name: 📝 Check CHANGELOG.md
+  check-changesets:
+    name: 📝 Check changesets
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -25,9 +25,9 @@ jobs:
           node-version: 20
 
       - run: yarn install
-        working-directory: ./.github/actions/check_changelog
+        working-directory: ./.github/actions/check_changesets
 
-      - name: Check CHANGELOG.md
-        uses: ./.github/actions/check_changelog
+      - name: Check changesets
+        uses: ./.github/actions/check_changesets
         with:
           labels: '{ "labels": ${{ toJSON(github.event.pull_request.labels) }} }'

package.json

@@ -18,6 +18,7 @@
     "build:pack": "nx run-many -t build:pack",
     "build:test-project": "node ./tasks/test-project/test-project",
     "build:watch": "lerna run build:watch --parallel; tsc --build",
+    "changesets": "tsx ./tasks/changesets/changesets.mts",
     "check": "node ./tasks/check/check.mjs",
     "clean:prisma": "rimraf node_modules/.prisma/client && node node_modules/@prisma/client/scripts/postinstall.js",
     "e2e": "node ./tasks/run-e2e",
@@ -89,6 +90,7 @@
     "execa": "5.1.1",
     "fast-glob": "3.3.2",
     "fs-extra": "11.2.0",
+    "human-id": "^4.1.1",
     "jest": "29.7.0",
     "jscodeshift": "0.15.0",
     "lerna": "8.0.2",

tasks/changesets/changesets.mts

@@ -0,0 +1,50 @@
+import { chalk, fs } from 'zx'
+
+import {
+  getChangesetFilePath,
+  getPlaceholder,
+  resolveArgv,
+  shouldShowHelp,
+  showHelp,
+} from './changesetsHelpers.mjs'
+
+async function main() {
+  if (shouldShowHelp()) {
+    showHelp()
+    return
+  }
+
+  const { prNumber } = resolveArgv()
+
+  const changesetFilePath = getChangesetFilePath(prNumber)
+  const placeholder = await getPlaceholder(prNumber)
+  await fs.outputFile(changesetFilePath, placeholder)
+  console.log(
+    [
+      `📝 Created a changeset at ${chalk.magenta(changesetFilePath)}`,
+      "   Commit it when you're done and push your branch up to GitHub. Thank you! 🙏",
+    ].join('\n')
+  )
+}
+
+try {
+  await main()
+} catch (error) {
+  console.error(`${error.message}\n`)
+  showHelp()
+  process.exitCode = 1
+}
+
+// Test suite
+//
+// - should be the placeholder at ./placeholder.md
+//   - yarn changesets
+//
+// - should be the title and body of PR 10075
+//   - yarn changesets 10075
+//   - yarn changesets '#10075'
+//
+// - should throw and show help
+//   - yarn changesets abcd
+//   - yarn changesets 10075000
+//   - yarn changesets https://github.com/redwoodjs/redwood/pull/10075