A manual re-post of a release announcement works

.github/workflows/announce.yml

@@ -32,16 +32,17 @@ jobs:
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
-      # Both triggers end up with the same file, so the manual run and the automatic one cannot drift apart.
+      # Both triggers end up with the same file, so the manual run and the automatic one cannot drift apart. A step cannot
+      # change GITHUB_EVENT_PATH, which is why a manual run used to fail with "The event carries no release"; the script
+      # reads this file by its own name instead.
       - name: Gather the release
         env:
           GH_TOKEN: ${{ github.token }}
           TAG: ${{ github.event.release.tag_name || inputs.tag }}
         run: |
           set -euo pipefail
           gh api "repos/${GITHUB_REPOSITORY}/releases/tags/${TAG}" > release.json
-          jq '{release: .}' release.json > event.json
-          echo "GITHUB_EVENT_PATH=$PWD/event.json" >> "$GITHUB_ENV"
+          echo "RELEASE_FILE=$PWD/release.json" >> "$GITHUB_ENV"
 
       - name: Post it
         env:

tools/announce-release.mjs

@@ -220,9 +220,13 @@ async function post(webhook, message, loaded) {
 
 async function main() {
   const dryRun = process.argv.includes('--dry-run')
+  // A manual run has no release in GitHub's own event file, and a step cannot change GITHUB_EVENT_PATH, so the
+  // workflow fetches the release itself and names the file in RELEASE_FILE. An automatic run reads the event.
+  const releaseFile = process.env.RELEASE_FILE
   const eventPath = process.env.GITHUB_EVENT_PATH
-  if (!eventPath) throw new Error('No GITHUB_EVENT_PATH; run this from the workflow, which writes one either way')
-  const { release } = JSON.parse(readFileSync(eventPath, 'utf8'))
+  if (!releaseFile && !eventPath) throw new Error('No RELEASE_FILE or GITHUB_EVENT_PATH; run this from the workflow')
+  const parsed = JSON.parse(readFileSync(releaseFile || eventPath, 'utf8'))
+  const release = releaseFile ? parsed : parsed.release
   if (!release) throw new Error('The event carries no release')
 
   if (release.draft) return console.log('Draft release, nothing posted.')

tools/announce-release.test.mjs

@@ -198,3 +198,25 @@ test('two servers each receive their own ping, and the wall is downloaded once',
   assert.doesNotMatch(mmd.message.content, /1553093586705449062/)
   assert.ok(mmd.hasFile)
 })
+
+test('a manual re-post reads the release from RELEASE_FILE, which is the release itself and not an event around it', async () => {
+  const { spawn } = await import('node:child_process')
+  const { mkdtempSync, writeFileSync } = await import('node:fs')
+  const { tmpdir } = await import('node:os')
+  const { join } = await import('node:path')
+  const dir = mkdtempSync(join(tmpdir(), 'announce-'))
+  const file = join(dir, 'release.json')
+  writeFileSync(file, JSON.stringify(release))
+  const out = await new Promise((resolve) => {
+    let text = ''
+    const child = spawn(process.execPath, [new URL('./announce-release.mjs', import.meta.url).pathname, '--dry-run'], {
+      // GITHUB_EVENT_PATH points at an event with no release, as GitHub's own file does for a manual run.
+      env: { ...process.env, RELEASE_FILE: file, GITHUB_EVENT_PATH: join(dir, 'missing.json') },
+    })
+    child.stdout.on('data', (d) => (text += d))
+    child.on('exit', (code) => resolve({ code, text }))
+  })
+  assert.equal(out.code, 0)
+  assert.match(out.text, /Dry run\. This is the message:/)
+  assert.match(out.text, /v0\.6\.6|0\.6\.6/)
+})