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

hive-c0re/src/meta.rs

@@ -668,6 +668,7 @@ struct OtelConfig {
     protocol: String,
     extra_resource_attributes: Option<String>,
     headers_credential: Option<String>,
+    metric_interval_ms: Option<u64>,
 }
 
 /// Read the hive-wide OTEL config from env, or `None` when OTEL is off.
@@ -690,11 +691,16 @@ fn otel_config() -> Option<OtelConfig> {
     let headers_credential = std::env::var("HYPERHIVE_OTEL_HEADERS_CREDENTIAL")
         .ok()
         .filter(|v| !v.is_empty());
+    let metric_interval_ms = std::env::var("HYPERHIVE_OTEL_METRIC_INTERVAL_MS")
+        .ok()
+        .and_then(|v| v.parse::<u64>().ok())
+        .filter(|v| *v > 0);
     Some(OtelConfig {
         endpoint,
         protocol,
         extra_resource_attributes,
         headers_credential,
+        metric_interval_ms,
     })
 }
 
@@ -982,6 +988,11 @@ where
                 esc(cred)
             );
         }
+        if let Some(ms) = otel.metric_interval_ms {
+            // Int option — emit a bare numeric literal (no quotes). `ms` is a
+            // parsed u64, so it can't inject anything into the rendered nix.
+            let _ = writeln!(out, "              hyperhive.otel.metricIntervalMs = {ms};");
+        }
     }
     out.push_str(
         r#"              # The harness service inside the container runs as a

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

nix/templates/harness-base.nix

@@ -250,6 +250,17 @@ in
         Host-driven via `services.hyperhive.otel.extraResourceAttributes`.
       '';
     };
+
+    metricIntervalMs = lib.mkOption {
+      type = lib.types.nullOr lib.types.ints.positive;
+      default = null;
+      internal = true;
+      description = ''
+        Metric export interval in milliseconds, set as
+        `OTEL_METRIC_EXPORT_INTERVAL`. Null leaves Claude Code's 60s
+        default. Host-driven via `services.hyperhive.otel.metricIntervalMs`.
+      '';
+    };
   };
 
   options.hyperhive.allowedRecipients = lib.mkOption {
@@ -1735,16 +1746,28 @@ in
         # Claude Code's native OpenTelemetry is env-driven; the harness
         # spawns `claude` as a child which inherits this unit's env, so
         # setting these here is all it takes to export per-agent stats.
-        otelEnv = lib.optionalAttrs otel.enable {
-          CLAUDE_CODE_ENABLE_TELEMETRY = "1";
-          OTEL_METRICS_EXPORTER = "otlp";
-          OTEL_LOGS_EXPORTER = "otlp";
-          # Route traces to OTLP too so any spans Claude Code emits land
-          # at the configured collector rather than a default exporter.
-          OTEL_TRACES_EXPORTER = "otlp";
-          OTEL_EXPORTER_OTLP_PROTOCOL = otel.protocol;
-          OTEL_EXPORTER_OTLP_ENDPOINT = otel.endpoint;
-        };
+        otelEnv = lib.optionalAttrs otel.enable (
+          {
+            CLAUDE_CODE_ENABLE_TELEMETRY = "1";
+            OTEL_METRICS_EXPORTER = "otlp";
+            OTEL_LOGS_EXPORTER = "otlp";
+            # Route traces to OTLP too so any spans Claude Code emits land
+            # at the configured collector rather than a default exporter.
+            OTEL_TRACES_EXPORTER = "otlp";
+            OTEL_EXPORTER_OTLP_PROTOCOL = otel.protocol;
+            OTEL_EXPORTER_OTLP_ENDPOINT = otel.endpoint;
+            # Force CUMULATIVE metric temporality. Claude Code defaults to
+            # DELTA, which Prometheus/Mimir-family backends (the common case,
+            # incl. grafana-lgtm) silently drop unless a deltatocumulative
+            # processor is wired — so delta = "logs arrive, metrics vanish".
+            # Cumulative is what those backends ingest natively. Verified:
+            # a delta export never registers the metric name; cumulative does.
+            OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE = "cumulative";
+          }
+          // lib.optionalAttrs (otel.metricIntervalMs != null) {
+            OTEL_METRIC_EXPORT_INTERVAL = toString otel.metricIntervalMs;
+          }
+        );
         # When OTEL is on, wrap the harness launch so (1) the bearer-token
         # header is read from the systemd credential at start (never in the
         # nix store or argv) and (2) the resource attributes are assembled