feat(release): auto-add RC tasks to checklist in create-rc

- Add `add_rc_task_to_body` to `release_issue.py` to dynamically insert new `Tag RC<N>` tasks into the checklist before `Tag Final`.
- Modify `create_rc.py` to detect if the next RC task is missing from the checklist, and if so, auto-add it and update the tracking issue body before proceeding.
- Add `test_create_rc_auto_add_task` to `create_rc_test.py` to verify this behavior.

Author: rickeylev

tests/tools/private/release/create_rc_test.py

@@ -1,3 +1,4 @@
+import argparse
 import os
 import pathlib
 import tempfile
@@ -212,6 +213,46 @@ def test_create_rc_with_finished_backports(self):
         self.mock_git.tag.assert_called_once_with("2.0.0-rc0", "my-remote/release/2.0")
         self.mock_git.push.assert_called_once_with("my-remote", "2.0.0-rc0")
 
+    def test_create_rc_auto_add_task(self):
+        # Arrange
+        args = argparse.Namespace(issue=123, remote="my-remote")
+        self.mock_gh.get_issue_title.return_value = "Release 2.0.0"
+        self.mock_gh.get_issue_body.return_value = """
+## Checklist
+- [x] Prepare Release | status=done pr=#122 commit=abcdef12
+- [x] Create Release branch | status=done branch=release/2.0 commit=abcdef12
+- [x] Tag RC0 | status=done tag=2.0.0-rc0 commit=abcdef12
+- [ ] Tag Final
+"""
+        self.mock_git.get_remote_tags.return_value = ["2.0.0-rc0"]
+        self.mock_git.get_commit_sha.return_value = "1234567890"
+
+        # Act
+        result = CreateRc(args, self.mock_git, self.mock_gh).run()
+
+        # Assert
+        self.assertEqual(result, 0)
+        self.mock_git.tag.assert_called_once_with("2.0.0-rc1", "my-remote/release/2.0")
+        self.mock_git.push.assert_called_once_with("my-remote", "2.0.0-rc1")
+
+        self.assertEqual(self.mock_gh.update_issue_body.call_count, 2)
+        call1_args = self.mock_gh.update_issue_body.call_args_list[0][0]
+        call2_args = self.mock_gh.update_issue_body.call_args_list[1][0]
+
+        self.assertEqual(call1_args[0], 123)
+        self.assertIn("- [ ] Tag RC1", call1_args[1])
+        self.assertIn(
+            "- [x] Tag RC0 | status=done tag=2.0.0-rc0 commit=abcdef12\n- [ ]"
+            " Tag RC1\n- [ ] Tag Final",
+            call1_args[1].strip(),
+        )
+
+        self.assertEqual(call2_args[0], 123)
+        self.assertIn(
+            "- [x] Tag RC1 | status=done tag=2.0.0-rc1 commit= 12345678",
+            call2_args[1],
+        )
+
 
 if __name__ == "__main__":
     unittest.main()

tools/private/release/create_rc.py

@@ -4,6 +4,7 @@
 from tools.private.release.git import Git
 from tools.private.release.release_issue import (
     RELEASE_TITLE_RE,
+    add_rc_task_to_body,
     parse_backports,
     parse_checklist_state,
     update_task_in_body,
@@ -77,19 +78,17 @@ def run(self) -> int:
         # Precheck: next RC number must exist and be unchecked in the checklist
         rc_tags = state.get("rc_tags", {})
         if next_rc_num not in rc_tags:
-            print(
-                f"Error: Checklist is missing required task 'Tag RC{next_rc_num}'"
-                f" to cut {version}-rc{next_rc_num}."
-            )
-            return 1
-
-        target_rc_task = rc_tags[next_rc_num]
-        if target_rc_task.checked or target_rc_task.status == "done":
-            print(
-                f"Error: Task 'Tag RC{next_rc_num}' is already marked done in"
-                " the checklist."
-            )
-            return 1
+            print(f"Task 'Tag RC{next_rc_num}' not found in checklist. Adding it...")
+            body = add_rc_task_to_body(body, next_rc_num)
+            self.gh.update_issue_body(args.issue, body)
+        else:
+            target_rc_task = rc_tags[next_rc_num]
+            if target_rc_task.checked or target_rc_task.status == "done":
+                print(
+                    f"Error: Task 'Tag RC{next_rc_num}' is already marked done in"
+                    " the checklist."
+                )
+                return 1
 
         target_ref = f"{args.remote}/{branch_name}"
         commit_sha = self.git.get_commit_sha(target_ref)

tools/private/release/release_issue.py

@@ -284,3 +284,32 @@ def add_backports_to_body(body: str, prs: list[int]) -> str:
     # Replace the old section with the updated one
     start, end = match.span(2)
     return body[:start] + updated_section + body[end:]
+
+
+def add_rc_task_to_body(body: str, rc_num: int) -> str:
+    """Adds a new 'Tag RC<rc_num>' task to the checklist in the issue body."""
+    body = body.replace("\r\n", "\n")
+    lines = body.splitlines()
+
+    # Find the index of the last "Tag RC<M>" line
+    last_rc_idx = -1
+    for i, line in enumerate(lines):
+        parsed = parse_metadata_line(line)
+        if parsed and re.match(r"Tag RC\d+", parsed["name"], re.IGNORECASE):
+            last_rc_idx = i
+
+    if last_rc_idx == -1:
+        # If no RC task found (unexpected, but fallback to before "Tag Final")
+        for i, line in enumerate(lines):
+            parsed = parse_metadata_line(line)
+            if parsed and parsed["name"].lower() == "tag final":
+                last_rc_idx = i - 1
+                break
+
+    if last_rc_idx == -1:
+        raise ValueError("Could not find a place to insert the new RC task.")
+
+    new_task_line = f"- [ ] Tag RC{rc_num}"
+    lines.insert(last_rc_idx + 1, new_task_line)
+
+    return "\n".join(lines)