fix(stack): normalize --branch by stripping prefix and change ID suffix

mergify_cli/stack/changes.py

@@ -29,7 +29,9 @@
     import httpx
 
 
-CHANGEID_RE = re.compile(r"Change-Id: (I[0-9a-z]{40})")
+_CHANGEID_PATTERN = r"I[0-9a-z]{40}"
+CHANGEID_RE = re.compile(rf"Change-Id: ({_CHANGEID_PATTERN})")
+CHANGEID_SUFFIX_RE = re.compile(rf"/{_CHANGEID_PATTERN}$")
 
 
 def is_change_id_prefix(prefix: str) -> bool:

mergify_cli/stack/checkout.py

@@ -39,6 +39,13 @@ async def stack_checkout(
     if branch_prefix is None:
         branch_prefix = await utils.get_default_branch_prefix(author)
 
+    # Strip change ID suffix if present (e.g. /Ibb431d523fb75f48f387a3964d2936ada933cffe)
+    branch = changes.CHANGEID_SUFFIX_RE.sub("", branch)
+
+    # Strip branch prefix from branch if already included
+    if branch_prefix and branch.startswith(f"{branch_prefix}/"):
+        branch = branch.removeprefix(f"{branch_prefix}/")
+
     stack_branch = f"{branch_prefix}/{branch}" if branch_prefix else branch
 
     async with utils.get_github_http_client(github_server, token) as client:

mergify_cli/stack/push.py

@@ -43,8 +43,7 @@ class LocalBranchInvalidError(Exception):
 
 
 def check_local_branch(branch_name: str, branch_prefix: str) -> None:
-    if branch_name.startswith(branch_prefix) and re.search(
-        r"I[0-9a-z]{40}$",
+    if branch_name.startswith(branch_prefix) and changes.CHANGEID_SUFFIX_RE.search(
         branch_name,
     ):
         msg = "Local branch is a branch generated by Mergify CLI"

mergify_cli/tests/stack/test_checkout.py

@@ -156,3 +156,74 @@ async def test_stack_checkout_repository_explicit(
         "--get",
         "remote.origin.url",
     )
+
+
+@pytest.mark.respx(base_url="https://api.github.com/")
+@pytest.mark.parametrize(
+    ("branch_input", "expected_branch"),
+    [
+        # Full head ref with prefix and change ID suffix → stripped to plain branch
+        (
+            "devs/JulianMaurin/MRGFY-6797/Ibb431d523fb75f48f387a3964d2936ada933cffe",
+            "MRGFY-6797",
+        ),
+        # Change ID suffix only → stripped
+        (
+            "MRGFY-6797/Ibb431d523fb75f48f387a3964d2936ada933cffe",
+            "MRGFY-6797",
+        ),
+        # Prefix only → stripped
+        (
+            "devs/JulianMaurin/MRGFY-6797",
+            "MRGFY-6797",
+        ),
+        # Already plain → unchanged
+        (
+            "MRGFY-6797",
+            "MRGFY-6797",
+        ),
+    ],
+    ids=[
+        "full-head-ref",
+        "with-suffix-no-prefix",
+        "with-prefix-no-suffix",
+        "plain-branch",
+    ],
+)
+async def test_stack_checkout_branch_normalization(
+    git_mock: test_utils.GitMock,
+    respx_mock: respx.MockRouter,
+    branch_input: str,
+    expected_branch: str,
+) -> None:
+    """Test that checkout normalizes --branch by stripping prefix and change ID suffix."""
+    git_mock.mock(
+        "config",
+        "--get",
+        "mergify-cli.stack-branch-prefix",
+        output="devs/JulianMaurin",
+    )
+
+    search_mock = respx_mock.get("/search/issues").respond(
+        200,
+        json={"items": []},
+    )
+
+    with pytest.raises(SystemExit, match="0"):
+        await stack_checkout_mod.stack_checkout(
+            github_server="https://api.github.com/",
+            token="",
+            user="user",
+            repo="repo",
+            branch_prefix=None,
+            branch=branch_input,
+            author="author",
+            trunk=("origin", "main"),
+            dry_run=True,
+        )
+
+    # Verify the search query: stack_branch = prefix/normalized_branch
+    expected_stack_branch = f"devs/JulianMaurin/{expected_branch}"
+    assert len(search_mock.calls) == 1
+    query = str(search_mock.calls[0].request.url)
+    assert f"head%3A{expected_stack_branch.replace('/', '%2F')}%2F" in query