(feat): restrict release branches in automation

ci/scripts/towncrier_automation.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 import argparse
+import re
 import subprocess
 from typing import TYPE_CHECKING
 
@@ -16,6 +17,14 @@ class Args(argparse.Namespace):
     dry_run: bool
 
 
+class NoPatchReleaseOnMainError(Exception):
+    pass
+
+
+class NoMinorMajorReleaseOffMainError(Exception):
+    pass
+
+
 def parse_args(argv: Sequence[str] | None = None) -> Args:
     parser = argparse.ArgumentParser(
         prog="towncrier-automation",
@@ -62,6 +71,17 @@ def main(argv: Sequence[str] | None = None) -> None:
         text=True,
         check=True,
     ).stdout.strip()
+    patch_branch_pattern = r"\d+\.\d+\.x"
+    if Version(args.version).micro != 0 and not re.fullmatch(
+        patch_branch_pattern, base_branch
+    ):
+        msg = f"Version {args.version} is a patch release, but "
+        "you are trying to release from a non-patch release branch: {base_branch}."
+        raise NoPatchReleaseOnMainError(msg)
+    if Version(args.version).micro == 0 and base_branch != "main":
+        msg = f"Version {args.version} is a minor or major release, "
+        "but you are trying to release not from main: {base_branch}."
+        raise NoMinorMajorReleaseOffMainError(msg)
     pr_description = "" if base_branch == "main" else "@meeseeksdev backport to main"
     branch_name = f"release_notes_{args.version}"