fix: harden pr review artifact validation

scripts/pr

@@ -500,6 +500,17 @@ EOF_MD
 {
   "recommendation": "READY FOR /prepare-pr",
   "findings": [],
+  "nitSweep": {
+    "performed": true,
+    "status": "none",
+    "summary": "No optional nits identified."
+  },
+  "issueValidation": {
+    "performed": true,
+    "source": "pr_body",
+    "status": "valid",
+    "summary": "PR description clearly states a valid problem."
+  },
   "tests": {
     "ran": [],
     "gaps": [],
@@ -559,6 +570,85 @@ review_validate_artifacts() {
     exit 1
   fi
 
+  local nit_findings_count
+  nit_findings_count=$(jq '[.findings[]? | select((.severity // "") == "NIT")] | length' .local/review.json)
+
+  local nit_sweep_performed
+  nit_sweep_performed=$(jq -r '.nitSweep.performed // empty' .local/review.json)
+  if [ "$nit_sweep_performed" != "true" ]; then
+    echo "Invalid nit sweep in .local/review.json: nitSweep.performed must be true"
+    exit 1
+  fi
+
+  local nit_sweep_status
+  nit_sweep_status=$(jq -r '.nitSweep.status // ""' .local/review.json)
+  case "$nit_sweep_status" in
+    "none")
+      if [ "$nit_findings_count" -gt 0 ]; then
+        echo "Invalid nit sweep in .local/review.json: nitSweep.status is none but NIT findings exist"
+        exit 1
+      fi
+      ;;
+    "has_nits")
+      if [ "$nit_findings_count" -lt 1 ]; then
+        echo "Invalid nit sweep in .local/review.json: nitSweep.status is has_nits but no NIT findings exist"
+        exit 1
+      fi
+      ;;
+    *)
+      echo "Invalid nit sweep status in .local/review.json: $nit_sweep_status"
+      exit 1
+      ;;
+  esac
+
+  local invalid_nit_summary_count
+  invalid_nit_summary_count=$(jq '[.nitSweep.summary | select((type != "string") or (gsub("^\\s+|\\s+$";"") | length == 0))] | length' .local/review.json)
+  if [ "$invalid_nit_summary_count" -gt 0 ]; then
+    echo "Invalid nit sweep summary in .local/review.json: nitSweep.summary must be a non-empty string"
+    exit 1
+  fi
+
+  local issue_validation_performed
+  issue_validation_performed=$(jq -r '.issueValidation.performed // empty' .local/review.json)
+  if [ "$issue_validation_performed" != "true" ]; then
+    echo "Invalid issue validation in .local/review.json: issueValidation.performed must be true"
+    exit 1
+  fi
+
+  local issue_validation_source
+  issue_validation_source=$(jq -r '.issueValidation.source // ""' .local/review.json)
+  case "$issue_validation_source" in
+    "linked_issue"|"pr_body"|"both")
+      ;;
+    *)
+      echo "Invalid issue validation source in .local/review.json: $issue_validation_source"
+      exit 1
+      ;;
+  esac
+
+  local issue_validation_status
+  issue_validation_status=$(jq -r '.issueValidation.status // ""' .local/review.json)
+  case "$issue_validation_status" in
+    "valid"|"unclear"|"invalid"|"already_fixed_on_main")
+      ;;
+    *)
+      echo "Invalid issue validation status in .local/review.json: $issue_validation_status"
+      exit 1
+      ;;
+  esac
+
+  local invalid_issue_summary_count
+  invalid_issue_summary_count=$(jq '[.issueValidation.summary | select((type != "string") or (gsub("^\\s+|\\s+$";"") | length == 0))] | length' .local/review.json)
+  if [ "$invalid_issue_summary_count" -gt 0 ]; then
+    echo "Invalid issue validation summary in .local/review.json: issueValidation.summary must be a non-empty string"
+    exit 1
+  fi
+
+  if [ "$recommendation" = "READY FOR /prepare-pr" ] && [ "$issue_validation_status" != "valid" ]; then
+    echo "Invalid recommendation in .local/review.json: READY FOR /prepare-pr requires issueValidation.status=valid"
+    exit 1
+  fi
+
   local docs_status
   docs_status=$(jq -r '.docs // ""' .local/review.json)
   case "$docs_status" in