Disable auto-merge for unsafe scheduler states

scripts/ci/pr_review_merge_scheduler.py

@@ -119,7 +119,7 @@ def decision_payload(
 ) -> dict[str, Any]:
     """Return the machine-readable scheduler decision contract."""
     return {
-        "schema_version": "pr-review-merge-scheduler/v1",
+        "schema_version": "pr-review-merge-scheduler/v2",
         "base_branch": base_branch,
         "dry_run": dry_run,
         "inspected": len(decisions),
@@ -197,9 +197,10 @@ def decision_guidance(decision: Decision) -> dict[str, Any] | None:
         }
     if decision.action == "disable_auto_merge":
         return {
-            "type": "fresh_head_review_required",
-            "summary": "Auto-merge was disabled because the PR needs fresh same-head review evidence before it can be merged.",
+            "type": "unsafe_auto_merge_disabled",
+            "summary": "Auto-merge was disabled because the current PR state is not safe to merge automatically.",
             "next_required_evidence": [
+                "the unsafe condition described in reason is repaired",
                 "OpenCode approval submitted after the current head commit was created",
                 "required GitHub Checks success on the current head",
                 "same-head Strix evidence",
@@ -496,6 +497,18 @@ def disable_auto_merge(repo: str, pr: dict[str, Any], *, dry_run: bool) -> None:
     run(["gh", "pr", "merge", number, "--repo", repo, "--disable-auto"])
 
 
+def disable_auto_merge_decision(
+    repo: str,
+    pr: dict[str, Any],
+    *,
+    dry_run: bool,
+    reason: str,
+) -> Decision:
+    """Disable auto-merge and return a WAIT decision with the concrete unsafe reason."""
+    disable_auto_merge(repo, pr, dry_run=dry_run)
+    return Decision(pr["number"], "disable_auto_merge", f"auto-merge disabled; {reason}")
+
+
 def update_branch(repo: str, pr: dict[str, Any], *, dry_run: bool) -> None:
     """Ask GitHub to update a PR branch, guarded by the observed head SHA."""
     number = str(pr["number"])
@@ -609,13 +622,34 @@ def inspect_pr(
 
     merge_state = (pr.get("mergeStateStatus") or "").upper()
     if merge_state in {"DIRTY", "CONFLICTING"}:
+        if pr.get("autoMergeRequest"):
+            return disable_auto_merge_decision(
+                repo,
+                pr,
+                dry_run=dry_run,
+                reason=f"{merge_conflict_guidance(pr, merge_state)}; repair the conflict before re-enabling auto-merge",
+            )
         return Decision(number, "block", merge_conflict_guidance(pr, merge_state))
 
     unresolved = unresolved_thread_count(pr)
     if unresolved:
+        if pr.get("autoMergeRequest"):
+            return disable_auto_merge_decision(
+                repo,
+                pr,
+                dry_run=dry_run,
+                reason=f"{unresolved} unresolved review thread(s); resolve the active thread(s) before re-enabling auto-merge",
+            )
         return Decision(number, "block", f"{unresolved} unresolved review thread(s)")
 
     if has_current_head_changes_requested(pr):
+        if pr.get("autoMergeRequest"):
+            return disable_auto_merge_decision(
+                repo,
+                pr,
+                dry_run=dry_run,
+                reason="current-head OpenCode review requested changes; address the review before re-enabling auto-merge",
+            )
         return Decision(number, "block", "current-head OpenCode review requested changes")
 
     current_head_approved = has_current_head_approval(pr)
@@ -630,16 +664,27 @@ def inspect_pr(
     if current_head_approved:
         failed_checks = failed_status_checks(pr)
         if failed_checks:
+            if pr.get("autoMergeRequest"):
+                return disable_auto_merge_decision(
+                    repo,
+                    pr,
+                    dry_run=dry_run,
+                    reason=f"failed check(s): {', '.join(failed_checks[:5])}; fix or rerun checks before re-enabling auto-merge",
+                )
             return Decision(number, "block", f"failed check(s): {', '.join(failed_checks[:5])}")
 
     if merge_state == "BEHIND" and current_head_approved:
         if not update_branches:
             return Decision(number, "wait", "current-head OpenCode review approved; branch update disabled")
+        had_auto_merge = bool(pr.get("autoMergeRequest"))
+        if had_auto_merge:
+            disable_auto_merge(repo, pr, dry_run=dry_run)
         update_branch(repo, pr, dry_run=dry_run)
+        prefix = "auto-merge disabled before branch update; " if had_auto_merge else ""
         return Decision(
             number,
             "update_branch",
-            "current-head OpenCode review approved; branch update requested with workflow GH_TOKEN (github-actions[bot] in GitHub Actions)",
+            f"{prefix}current-head OpenCode review approved; branch update requested with workflow GH_TOKEN (github-actions[bot] in GitHub Actions)",
         )
 
     if current_head_approved:
@@ -687,6 +732,14 @@ def inspect_pr(
             "current head has completed Strix evidence; same-head OpenCode dispatched",
         )
 
+    if pr.get("autoMergeRequest"):
+        return disable_auto_merge_decision(
+            repo,
+            pr,
+            dry_run=dry_run,
+            reason="current head has no OpenCode approval; wait for fresh same-head approval before re-enabling auto-merge",
+        )
+
     return Decision(number, "block", "current head has no OpenCode approval")
 
 
@@ -769,12 +822,14 @@ def write_actions_summary(
 def parse_conflict_reason(reason: str) -> tuple[str, str, str] | None:
     """Extract merge state, base branch, and head branch from conflict guidance."""
     prefix = "merge conflict: "
-    if not reason.startswith(prefix):
+    conflict_start = reason.find(prefix)
+    if conflict_start < 0:
         return None
-    state = reason[len(prefix) :].split(";", 1)[0].strip() or "UNKNOWN"
+    conflict_reason = reason[conflict_start:]
+    state = conflict_reason[len(prefix) :].split(";", 1)[0].strip() or "UNKNOWN"
     base_ref = "base"
     head_ref = "head"
-    for segment in reason.split(";"):
+    for segment in conflict_reason.split(";"):
         segment = segment.strip()
         if not segment.startswith("base="):
             continue
@@ -938,6 +993,7 @@ def self_test() -> None:
         base_branch="main",
     )
     assert decision.action == "auto_merge"
+    sample["autoMergeRequest"] = {"enabledAt": "2026-01-01T00:02:00Z"}
     sample["statusCheckRollup"]["contexts"]["nodes"] = [
         {"__typename": "CheckRun", "name": "strix", "status": "COMPLETED", "conclusion": "FAILURE"}
     ]
@@ -952,6 +1008,20 @@ def self_test() -> None:
         security_workflow="Strix Security Scan",
         base_branch="main",
     )
+    assert decision.action == "disable_auto_merge"
+    assert "failed check(s): strix" in decision.reason
+    sample["autoMergeRequest"] = None
+    decision = inspect_pr(
+        "owner/repo",
+        sample,
+        dry_run=True,
+        trigger_reviews=True,
+        enable_auto_merge_flag=True,
+        update_branches=True,
+        workflow="OpenCode Review",
+        security_workflow="Strix Security Scan",
+        base_branch="main",
+    )
     assert decision.action == "block"
     assert "strix" in decision.reason
     sample["statusCheckRollup"]["contexts"]["nodes"] = []
@@ -974,6 +1044,29 @@ def self_test() -> None:
         }
     )
     assert not has_current_head_changes_requested(sample)
+    sample["reviews"]["nodes"] = [
+        {
+            "state": "CHANGES_REQUESTED",
+            "author": {"login": "opencode-agent"},
+            "commit": {"oid": "abc"},
+        }
+    ]
+    sample["autoMergeRequest"] = {"enabledAt": "2026-01-01T00:02:00Z"}
+    assert has_current_head_changes_requested(sample)
+    decision = inspect_pr(
+        "owner/repo",
+        sample,
+        dry_run=True,
+        trigger_reviews=True,
+        enable_auto_merge_flag=True,
+        update_branches=True,
+        workflow="OpenCode Review",
+        security_workflow="Strix Security Scan",
+        base_branch="main",
+    )
+    assert decision.action == "disable_auto_merge"
+    assert "current-head OpenCode review requested changes" in decision.reason
+    sample["autoMergeRequest"] = None
     sample["statusCheckRollup"]["contexts"]["nodes"].append(
         {"__typename": "CheckRun", "name": "opencode-review", "status": "IN_PROGRESS"}
     )
@@ -1033,6 +1126,21 @@ def self_test() -> None:
         base_branch="main",
     )
     assert decision.action == "update_branch"
+    sample["autoMergeRequest"] = {"enabledAt": "2026-01-01T00:02:00Z"}
+    decision = inspect_pr(
+        "owner/repo",
+        sample,
+        dry_run=True,
+        trigger_reviews=True,
+        enable_auto_merge_flag=True,
+        update_branches=True,
+        workflow="OpenCode Review",
+        security_workflow="Strix Security Scan",
+        base_branch="main",
+    )
+    assert decision.action == "update_branch"
+    assert "auto-merge disabled before branch update" in decision.reason
+    sample["autoMergeRequest"] = None
     sample["statusCheckRollup"]["contexts"]["nodes"] = [
         {"__typename": "CheckRun", "name": "strix", "status": "COMPLETED", "conclusion": "FAILURE"}
     ]
@@ -1051,6 +1159,24 @@ def self_test() -> None:
     assert decision.reason == "failed check(s): strix"
     sample["statusCheckRollup"]["contexts"]["nodes"] = []
     sample["mergeStateStatus"] = "DIRTY"
+    sample["autoMergeRequest"] = {"enabledAt": "2026-01-01T00:02:00Z"}
+    decision = inspect_pr(
+        "owner/repo",
+        sample,
+        dry_run=True,
+        trigger_reviews=True,
+        enable_auto_merge_flag=True,
+        update_branches=True,
+        workflow="OpenCode Review",
+        security_workflow="Strix Security Scan",
+        base_branch="main",
+    )
+    assert decision.action == "disable_auto_merge"
+    assert "merge conflict: DIRTY" in decision.reason
+    conflict_guidance = decision_guidance(decision)
+    assert conflict_guidance
+    assert conflict_guidance["type"] == "merge_conflict_repair"
+    sample["autoMergeRequest"] = None
     decision = inspect_pr(
         "owner/repo",
         sample,
@@ -1078,6 +1204,7 @@ def self_test() -> None:
     assert contract_decision(Decision(1, "update_branch", "ok")) == "UPDATE_BRANCH"
     assert contract_decision(Decision(1, "wait", "ok")) == "WAIT"
     assert contract_decision(Decision(1, "action_error", "ok")) == "WAIT"
+    assert contract_decision(Decision(1, "disable_auto_merge", "ok")) == "WAIT"
     assert contract_decision(Decision(1, "auto_merge", "ok")) == "NO_ACTION"
     assert contract_decision(Decision(1, "skip", "ok")) == "NO_ACTION"
     assert (
@@ -1089,6 +1216,9 @@ def self_test() -> None:
     assert update_guidance
     assert update_guidance["actor"] == "github-actions[bot]"
     assert update_guidance["head_guard"] == "expected_head_sha"
+    disable_guidance = decision_guidance(Decision(1, "disable_auto_merge", "ok"))
+    assert disable_guidance
+    assert disable_guidance["type"] == "unsafe_auto_merge_disabled"
     assert decision_guidance(Decision(1, "wait", "ok")) is None
     payload = decision_payload(
         [Decision(1, "update_branch", "ok")],
@@ -1097,7 +1227,7 @@ def self_test() -> None:
         base_branch="main",
         project_flow="github-flow",
     )
-    assert payload["schema_version"] == "pr-review-merge-scheduler/v1"
+    assert payload["schema_version"] == "pr-review-merge-scheduler/v2"
     assert payload["decisions"][0]["contract_decision"] == "UPDATE_BRANCH"
     assert payload["decisions"][0]["guidance"]["actor"] == "github-actions[bot]"
     print("self-test passed")

tests/test_pr_review_merge_scheduler.py

@@ -426,7 +426,7 @@ def test_print_summary_writes_github_step_summary(monkeypatch, tmp_path, capsys)
     output = capsys.readouterr().out
     assert "PR #7: block: merge conflict: DIRTY" in output
     payload = json.loads(output.splitlines()[-1])
-    assert payload["schema_version"] == "pr-review-merge-scheduler/v1"
+    assert payload["schema_version"] == "pr-review-merge-scheduler/v2"
     assert payload["base_branch"] == "main"
     assert payload["counts"] == {"block": 1, "disable_auto_merge": 1, "update_branch": 1}
     assert payload["dry_run"] is True
@@ -447,7 +447,7 @@ def test_print_summary_writes_github_step_summary(monkeypatch, tmp_path, capsys)
     assert payload["decisions"][1]["guidance"]["token"] == "workflow GITHUB_TOKEN"
     assert payload["decisions"][1]["guidance"]["required_permission"] == "pull-requests: write"
     assert payload["decisions"][1]["guidance"]["head_guard"] == "expected_head_sha"
-    assert payload["decisions"][2]["guidance"]["type"] == "fresh_head_review_required"
+    assert payload["decisions"][2]["guidance"]["type"] == "unsafe_auto_merge_disabled"
     summary = summary_path.read_text(encoding="utf-8")
     assert "## PR review merge scheduler" in summary
     assert "| #7 | block | merge conflict: DIRTY; base=main, head=feature\\|x; run" in summary
@@ -519,6 +519,14 @@ def test_inspect_pr_blocks_and_waits_for_policy_states(monkeypatch):
     assert conflicting.action == "block"
     assert "merge conflict: CONFLICTING" in conflicting.reason
     assert inspect(make_pr(reviewThreads={"nodes": [{"isResolved": False}]})).reason == "1 unresolved review thread(s)"
+    unresolved_auto = inspect(
+        make_pr(
+            reviewThreads={"nodes": [{"isResolved": False}]},
+            autoMergeRequest={"enabledAt": "now"},
+        )
+    )
+    assert unresolved_auto.action == "disable_auto_merge"
+    assert "unresolved review thread" in unresolved_auto.reason
     assert inspect(make_pr(reviews={"nodes": [opencode_review("CHANGES_REQUESTED", "head")]})).reason == (
         "current-head OpenCode review requested changes"
     )
@@ -619,6 +627,9 @@ def test_inspect_pr_handles_approved_reviews_and_dispatch(monkeypatch):
     assert stale_wait.action == "wait"
     assert "review dispatch disabled" in stale_wait.reason
     assert inspect(make_pr(), trigger_reviews=False).reason == "current head has no OpenCode approval"
+    missing_approval_auto = inspect(make_pr(autoMergeRequest={"enabledAt": "now"}), trigger_reviews=False)
+    assert missing_approval_auto.action == "disable_auto_merge"
+    assert "no OpenCode approval" in missing_approval_auto.reason
 
 
 def test_print_summary_self_test_parse_args_and_main(monkeypatch, capsys):
@@ -631,7 +642,7 @@ def test_print_summary_self_test_parse_args_and_main(monkeypatch, capsys):
     output = capsys.readouterr().out
     assert "PR #1: wait: ready" in output
     payload = json.loads(output.strip().splitlines()[-1])
-    assert payload["schema_version"] == "pr-review-merge-scheduler/v1"
+    assert payload["schema_version"] == "pr-review-merge-scheduler/v2"
     assert payload["counts"] == {"wait": 2}
     assert [decision["contract_decision"] for decision in payload["decisions"]] == ["WAIT", "WAIT"]