fix(otel): cumulative metric temporality + metricIntervalMs knob (real metrics-export fix)

nix/modules/hive-c0re.nix

@@ -257,6 +257,23 @@ in
         `service.name` / `agent` / `hive` / `swarm` labels.
       '';
     };
+
+    metricIntervalMs = lib.mkOption {
+      type = lib.types.nullOr lib.types.ints.positive;
+      default = null;
+      example = 10000;
+      description = ''
+        Metric export interval in milliseconds, set as
+        `OTEL_METRIC_EXPORT_INTERVAL` for every agent. Claude Code's
+        default is 60000 (60s). Leave `null` to use that default.
+
+        Each agent runs claude as a short-lived per-turn process; claude
+        force-flushes metrics on shutdown, so this is not required for
+        metrics to be exported, but a lower value gives more frequent
+        intermediate flushes within long turns. Cosmetic, not a
+        correctness knob.
+      '';
+    };
   };
 
   # Peer hives in the same swarm. Each entry declares a remote hive
@@ -888,6 +905,9 @@ in
         // lib.optionalAttrs (otel.headersCredential != null) {
           HYPERHIVE_OTEL_HEADERS_CREDENTIAL = otel.headersCredential;
         }
+        // lib.optionalAttrs (otel.metricIntervalMs != null) {
+          HYPERHIVE_OTEL_METRIC_INTERVAL_MS = toString otel.metricIntervalMs;
+        }
       )
       // {
         # In-cluster forge URL — the gateway vhost (`forge.<domain>`), which