fix(rate-limits): treat empty policies as unlimited

apps/api/internal/runner/limits.go

@@ -83,11 +83,18 @@ func (s *Service) rateLimitReservations(ctx context.Context, user *auth.User, ca
 
 func effectiveRateLimitPolicy(candidate store.RuntimeModelCandidate) map[string]any {
 	policy := candidate.PlatformRateLimitPolicy
-	if hasRules(candidate.RuntimeRateLimitPolicy) {
+	if strings.TrimSpace(candidate.RuntimePolicySetID) != "" {
+		policy = candidate.RuntimeRateLimitPolicy
+	} else if hasRules(candidate.RuntimeRateLimitPolicy) {
 		policy = mergeMap(policy, candidate.RuntimeRateLimitPolicy)
 	}
-	if nested, ok := candidate.RuntimePolicyOverride["rateLimitPolicy"].(map[string]any); ok && len(nested) > 0 {
-		policy = mergeMap(policy, nested)
+	if _, hasOverride := candidate.RuntimePolicyOverride["rateLimitPolicy"]; hasOverride {
+		nested, _ := candidate.RuntimePolicyOverride["rateLimitPolicy"].(map[string]any)
+		if len(nested) == 0 {
+			policy = nil
+		} else {
+			policy = mergeMap(policy, nested)
+		}
 	}
 	if hasRules(candidate.ModelRateLimitPolicy) {
 		policy = mergeMap(policy, candidate.ModelRateLimitPolicy)
@@ -123,6 +130,9 @@ func reservationsFromPolicy(scopeType string, scopeKey string, scopeName string,
 		rule, _ := rawRule.(map[string]any)
 		metric := strings.TrimSpace(stringFromMap(rule, "metric"))
 		limit := floatFromAny(rule["limit"])
+		if metric == "" || limit <= 0 {
+			continue
+		}
 		amount := 1.0
 		if strings.HasPrefix(metric, "tpm") {
 			amount = float64(estimatedTokens)