Prevent npm alpha dist-tags from moving backward (#49704)

## Why

Publishing an older alpha or alpha hotfix can overwrite npm dist-tags that already point to a newer release.

## What changed

Check each package's current npm dist-tag before publishing an alpha release, using the existing release version comparison and workflow concurrency lock. Handle `alpha` and platform-specific tags independently for Codex, the SDK, and the responses API proxy.

When the release does not advance the current version, publish under `release-<version>-<tag>` to keep it installable without changing the alpha or `latest` tags. Abort publishing if the registry lookup fails.

## Testing

Add unit tests for package and platform tag selection, older releases, dotted alpha hotfixes, missing tags, and registry lookup failures.

GitOrigin-RevId: 9c0edec1149bf78c01aac0f700e963630316eaea

.github/scripts/npm_alpha_tag.py

@@ -0,0 +1,43 @@
+"""Choose a forward-only npm alpha dist-tag under rust-release's concurrency lock."""
+
+import json
+from pathlib import Path
+import subprocess
+import sys
+import tarfile
+
+from releases import should_update_version
+
+
+def npm_alpha_tag(tarball: Path, version: str, tag: str) -> str:
+    # Read the actual package name: platform archives share @openai/codex,
+    # while the SDK and proxy have independent alpha pointers.
+    with tarfile.open(tarball, "r:gz") as archive:
+        with archive.extractfile("package/package.json") as manifest:
+            package = json.load(manifest)["name"]
+
+    result = subprocess.run(
+        ["npm", "view", package, "dist-tags", "--json", "--prefer-online"],
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    current = json.loads(result.stdout).get(tag, "")
+    if tag != "alpha":
+        # build_npm_package.py appends -<platform> to the release version.
+        current = current.removesuffix(f"-{tag.removeprefix('alpha-')}")
+    if should_update_version(version, current):
+        return tag
+
+    # npm publish always writes a tag. Keep this version installable without
+    # changing alpha, alpha-<platform>, or latest. Prefix avoids semver tags,
+    # which npm rejects. Include the platform for versions of the same package.
+    print(
+        f"Keeping {package}@{tag} at {current}; publishing {version} separately",
+        file=sys.stderr,
+    )
+    return f"release-{version}-{tag}"
+
+
+if __name__ == "__main__":
+    print(npm_alpha_tag(Path(sys.argv[1]), sys.argv[2], sys.argv[3]))

.github/scripts/test_releases.py

@@ -1,5 +1,13 @@
+import io
+import json
+from pathlib import Path
+import subprocess
+import tarfile
+import tempfile
 import unittest
+from unittest.mock import patch
 
+from npm_alpha_tag import npm_alpha_tag
 from releases import is_valid_release_version, should_update_version
 
 
@@ -52,5 +60,92 @@ class VersionComparisonTest(unittest.TestCase):
         self.assertRaises(ValueError, should_update_version, "0.123", "")
 
 
+class NpmAlphaTagTest(unittest.TestCase):
+    def test_published_tags_across_packages_and_platforms(self) -> None:
+        # Each package/tag reads its own registry value, even after a partially
+        # published release. Also exercise a missing pointer and dotted hotfix.
+        cases = [
+            (
+                "@openai/codex",
+                "alpha",
+                "0.158.0-alpha.10",
+                "0.157.0-alpha.11.1",
+                "release-0.157.0-alpha.11.1-alpha",
+            ),
+            (
+                "@openai/codex",
+                "alpha-linux-x64",
+                "0.158.0-alpha.10-linux-x64",
+                "0.157.0-alpha.11.1",
+                "release-0.157.0-alpha.11.1-alpha-linux-x64",
+            ),
+            (
+                "@openai/codex",
+                "alpha-win32-arm64",
+                "0.158.0-alpha.9-win32-arm64",
+                "0.158.0-alpha.10",
+                "alpha-win32-arm64",
+            ),
+            (
+                "@openai/codex-sdk",
+                "alpha",
+                "0.158.0-alpha.10",
+                "0.158.0-alpha.10.1",
+                "alpha",
+            ),
+            (
+                "@openai/codex-responses-api-proxy",
+                "alpha",
+                "0.159.0-alpha.1",
+                "0.158.0-alpha.10.1",
+                "release-0.158.0-alpha.10.1-alpha",
+            ),
+            ("@openai/codex-sdk", "alpha", None, "0.158.0-alpha.10", "alpha"),
+        ]
+        with tempfile.TemporaryDirectory() as tmpdir:
+            tarball = Path(tmpdir) / "package.tgz"
+            for package, tag, current, version, expected in cases:
+                with self.subTest(package=package, tag=tag, version=version):
+                    content = json.dumps({"name": package}).encode()
+                    with tarfile.open(tarball, "w:gz") as archive:
+                        info = tarfile.TarInfo("package/package.json")
+                        info.size = len(content)
+                        archive.addfile(info, io.BytesIO(content))
+                    tags = {tag: current} if current is not None else {}
+                    result = subprocess.CompletedProcess([], 0, json.dumps(tags))
+                    with patch(
+                        "npm_alpha_tag.subprocess.run", return_value=result
+                    ) as run:
+                        self.assertEqual(npm_alpha_tag(tarball, version, tag), expected)
+                    run.assert_called_once_with(
+                        [
+                            "npm",
+                            "view",
+                            package,
+                            "dist-tags",
+                            "--json",
+                            "--prefer-online",
+                        ],
+                        check=True,
+                        capture_output=True,
+                        text=True,
+                    )
+
+    def test_registry_failure_prevents_publish(self) -> None:
+        with tempfile.TemporaryDirectory() as tmpdir:
+            tarball = Path(tmpdir) / "package.tgz"
+            content = b'{"name": "@openai/codex"}'
+            with tarfile.open(tarball, "w:gz") as archive:
+                info = tarfile.TarInfo("package/package.json")
+                info.size = len(content)
+                archive.addfile(info, io.BytesIO(content))
+            with patch(
+                "npm_alpha_tag.subprocess.run",
+                side_effect=subprocess.CalledProcessError(1, "npm"),
+            ):
+                with self.assertRaises(subprocess.CalledProcessError):
+                    npm_alpha_tag(tarball, "0.158.0-alpha.10", "alpha")
+
+
 if __name__ == "__main__":
     unittest.main()