chore(maint): make the PR merge drift guard advisory by default (#100593)

steipete · web-flow · commit 785f197de600 · 2026-07-06T05:14:39.000+01:00
The relevant-mainline-drift check in scripts/pr merge-verify hard-failed
any landing whose prepared head predated a sibling merge, serializing all
agent landings behind a fresh CI cycle per merged PR. Required checks
still gate at the prepared head and GitHub mergeable state still blocks
real conflicts. OPENCLAW_PR_STRICT_DRIFT=1 restores the previous hard
gate for release-critical flows.
diff --git a/scripts/pr-lib/merge.sh b/scripts/pr-lib/merge.sh
@@ -164,10 +164,19 @@ merge_verify() {
       "${PREP_MAINLINE_BASE_SHA:-${LOCAL_PREP_HEAD_SHA:-$PREP_HEAD_SHA}}" \
       "$PREP_HEAD_SHA"
     then
-      echo "Merge verify failed: mainline drift is relevant to this PR; run scripts/pr prepare-sync-head $pr before merge."
-      exit 1
+      # Relevant drift is advisory by default: required checks are already
+      # green at the prepared head and GitHub's mergeable state still blocks
+      # true conflicts. The hard fail serialized every landing behind a full
+      # CI cycle per merged sibling, which collapses under multi-session
+      # traffic. Set OPENCLAW_PR_STRICT_DRIFT=1 to restore the hard gate.
+      if [ "${OPENCLAW_PR_STRICT_DRIFT:-}" = "1" ]; then
+        echo "Merge verify failed: mainline drift is relevant to this PR; run scripts/pr prepare-sync-head $pr before merge."
+        exit 1
+      fi
+      echo "Merge verify: WARNING — mainline drift is relevant to this PR; proceeding (OPENCLAW_PR_STRICT_DRIFT=1 restores the hard gate)."
+    else
+      echo "Merge verify: continuing without prep-head sync because behind-main drift is unrelated."
     fi
-    echo "Merge verify: continuing without prep-head sync because behind-main drift is unrelated."
   fi
 
   echo "merge-verify passed for PR #$pr"
