fix(pr-review): treat LOW-only findings as ready to merge (#455)

LOW severity findings are explicitly non-blocking suggestions, but the
verdict logic was returning MERGE_WITH_CHANGES instead of READY_TO_MERGE.
This was inconsistent with the documented behavior and the rationale
text which stated these items were "safe to merge" and "non-blocking".

Updated verdict determination in followup_reviewer, orchestrator, and
parallel_orchestrator_reviewer to return READY_TO_MERGE when only LOW
severity findings remain.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

apps/backend/runners/github/orchestrator.py

@@ -799,9 +799,11 @@ class GitHubOrchestrator:
             if low:
                 reasoning += f", {len(low)} suggestions"
         elif low:
-            # Only Low severity suggestions - can merge but consider addressing
-            verdict = MergeVerdict.MERGE_WITH_CHANGES
-            reasoning = f"{len(low)} suggestion(s) to consider"
+            # Only Low severity suggestions - safe to merge (non-blocking)
+            verdict = MergeVerdict.READY_TO_MERGE
+            reasoning = (
+                f"No blocking issues. {len(low)} non-blocking suggestion(s) to consider"
+            )
         else:
             verdict = MergeVerdict.READY_TO_MERGE
             reasoning = "No blocking issues found"

apps/backend/runners/github/services/followup_reviewer.py

@@ -485,11 +485,11 @@ class FollowupReviewer:
                 f"({high_unresolved + medium_unresolved} unresolved, {high_new + medium_new} new)"
             )
         elif low_unresolved > 0 or low_new > 0:
-            # Only Low severity suggestions remaining - can merge but consider addressing
-            verdict = MergeVerdict.MERGE_WITH_CHANGES
+            # Only Low severity suggestions remaining - safe to merge (non-blocking)
+            verdict = MergeVerdict.READY_TO_MERGE
             reasoning = (
                 f"{resolved_count} issues resolved. "
-                f"{low_unresolved + low_new} suggestion(s) to consider."
+                f"{low_unresolved + low_new} non-blocking suggestion(s) to consider."
             )
         else:
             verdict = MergeVerdict.READY_TO_MERGE

apps/backend/runners/github/services/parallel_orchestrator_reviewer.py

@@ -743,9 +743,11 @@ The SDK will run invoked agents in parallel automatically.
             if low:
                 reasoning += f", {len(low)} suggestions"
         elif low:
-            # Only Low severity suggestions - can merge but consider addressing
-            verdict = MergeVerdict.MERGE_WITH_CHANGES
-            reasoning = f"{len(low)} suggestion(s) to consider"
+            # Only Low severity suggestions - safe to merge (non-blocking)
+            verdict = MergeVerdict.READY_TO_MERGE
+            reasoning = (
+                f"No blocking issues. {len(low)} non-blocking suggestion(s) to consider"
+            )
         else:
             verdict = MergeVerdict.READY_TO_MERGE
             reasoning = "No blocking issues found"