feat(release): don't warn when devstack main is ahead only by the VERSION strip

The stable branch's stripped-VERSION commit exists on main by design until
dev advances — status now shows it as expected instead of a problem.

Author: localpibox

scripts/localpibox/stack/release.py

@@ -242,6 +242,14 @@ def _repo_action(st: dict, rebase: bool) -> tuple[str, str | None]:
     return st["feasibility"], None  # ff | merge
 
 
+def _main_unique_is_version_only(path: Path, dev_b: str, main_b: str) -> bool:
+    """True when main's tree differs from dev only in VERSION (the expected
+    stable-branch strip after a promotion, until dev advances again)."""
+    out, _err, code = git(path, "diff", "--name-only",
+                          f"origin/{dev_b}", f"origin/{main_b}")
+    return code == 0 and all(f == "VERSION" for f in out.splitlines() if f)
+
+
 def _set_commit_author() -> None:
     """Force LocalPibox author identity for git commits made by this process."""
     os.environ["GIT_AUTHOR_NAME"] = "localpibox"
@@ -270,8 +278,13 @@ def cmd_release_status(cons: Console) -> int:
         elif feas == "aligned":
             mark, note = "✅", "aligned"
         elif feas == "ahead":
-            mark, note = "⚠️", f"{main_b} is AHEAD of dev — check its unique commits"
-            problems += 1
+            if label == "devstack" and _main_unique_is_version_only(path, dev_b, main_b):
+                mark, note = "✅", (f"{main_b} ahead only by the stable VERSION "
+                                    f"strip (expected after a release, until "
+                                    f"dev advances)")
+            else:
+                mark, note = "⚠️", f"{main_b} is AHEAD of dev — check its unique commits"
+                problems += 1
         elif feas == "ff":
             mark, note = "✅", f"{main_b} {st['main_behind_by']} behind → fast-forward"
         elif feas == "merge":

scripts/test_localpibox_release.py

@@ -214,6 +214,22 @@ def test_release_state_real_conflict(tmpdir):
     assert st["feasibility"] == "conflict"
 
 
+def test_main_unique_version_only(tmpdir):
+    """After a promotion, main is ahead of dev only by the VERSION strip —
+    status must not warn about it."""
+    clone = _fake_release_repo(tmpdir)
+    p1, p2 = _patch_release(clone, tmpdir)
+    with p1, p2:
+        # main (0.0.8-lpb) vs dev (0.0.9-lpb-dev): main's unique change is VERSION
+        assert rel._main_unique_is_version_only(clone, "dev", "main") is False
+        # simulate the post-release state: main == merge(dev) + VERSION strip
+        _g(clone, "checkout", "-q", "-B", "main", "origin/dev")
+        (clone / "VERSION").write_text("0.0.9-lpb\n")
+        _g(clone, "commit", "-qam", "strip")
+        _g(clone, "push", "-q", "origin", "main")
+        assert rel._main_unique_is_version_only(clone, "dev", "main") is True
+
+
 # ─── docs-ready command end-to-end ────────────────────────────────────────
 
 def test_docs_ready_flags_and_pushes(tmpdir):