fix(pr): make review claim step required

scripts/pr

@@ -20,6 +20,7 @@ Usage:
   scripts/pr review-init <PR>
   scripts/pr review-checkout-main <PR>
   scripts/pr review-checkout-pr <PR>
+  scripts/pr review-claim <PR>
   scripts/pr review-guard <PR>
   scripts/pr review-artifacts-init <PR>
   scripts/pr review-validate-artifacts <PR>
@@ -396,6 +397,60 @@ REVIEW_MODE_SET_AT=$(date -u +%Y-%m-%dT%H:%M:%SZ)
 EOF_ENV
 }
 
+review_claim() {
+  local pr="$1"
+  local root
+  root=$(repo_root)
+  cd "$root"
+  mkdir -p .local
+
+  local reviewer=""
+  local max_attempts=3
+  local attempt
+
+  for attempt in $(seq 1 "$max_attempts"); do
+    local user_log
+    user_log=".local/review-claim-user-attempt-$attempt.log"
+
+    if reviewer=$(gh api user --jq .login 2>"$user_log"); then
+      printf "%s\n" "$reviewer" >"$user_log"
+      break
+    fi
+
+    echo "Claim reviewer lookup failed (attempt $attempt/$max_attempts)."
+    print_relevant_log_excerpt "$user_log"
+
+    if [ "$attempt" -lt "$max_attempts" ]; then
+      sleep 2
+    fi
+  done
+
+  if [ -z "$reviewer" ]; then
+    echo "Failed to resolve reviewer login after $max_attempts attempts."
+    return 1
+  fi
+
+  for attempt in $(seq 1 "$max_attempts"); do
+    local claim_log
+    claim_log=".local/review-claim-assignee-attempt-$attempt.log"
+
+    if gh pr edit "$pr" --add-assignee "$reviewer" >"$claim_log" 2>&1; then
+      echo "review claim succeeded: @$reviewer assigned to PR #$pr"
+      return 0
+    fi
+
+    echo "Claim assignee update failed (attempt $attempt/$max_attempts)."
+    print_relevant_log_excerpt "$claim_log"
+
+    if [ "$attempt" -lt "$max_attempts" ]; then
+      sleep 2
+    fi
+  done
+
+  echo "Failed to assign @$reviewer to PR #$pr after $max_attempts attempts."
+  return 1
+}
+
 review_checkout_main() {
   local pr="$1"
   enter_worktree "$pr" false
@@ -1766,6 +1821,9 @@ main() {
     review-checkout-pr)
       review_checkout_pr "$pr"
       ;;
+    review-claim)
+      review_claim "$pr"
+      ;;
     review-guard)
       review_guard "$pr"
       ;;