chore(rivetkit): clean up metrics naming and dead collectors

- Rename rivetkit_core::metrics_endpoint to rivetkit_core::metrics; the
  module only renders the registry and records rivetkit_info now.
- Start the tokio runtime sampler explicitly at the three startup call
  sites instead of as a side effect of record_rivetkit_info().
- Delete registry/process-metrics.ts, which had no importers and no
  NAPI counterparts.
- Drop the unused --metrics-token flag and _RIVET_METRICS_TOKEN env
  passthrough from the kitchen-sink soak and mock-agentic scripts.

Amp-Thread-ID: https://ampcode.com/threads/T-e7d8deec-a004-4884-a5b2-8d5c9064977c
Co-authored-by: Amp <amp@ampcode.com>

Author: ampagent

docs-internal/engine/rivetkit-core-internals.md

@@ -67,7 +67,7 @@ Legacy traces under `[7, 1, ...]` are intentionally skipped and are not copied t
 
 - Registry startup builds configured `ActorContext`s with `ActorContext::build(...)` so state, queue, and connection managers inherit the actor config before lifecycle startup runs. `ActorContext::build(...)` must seed owned queue, connection, and sleep config storage from its `ActorConfig`; do not initialize those fields with `ActorConfig::default()`.
 - Registry actor task handles live in one `actor_instances: SccHashMap<String, ActorInstanceState>`. Use `entry_async` for Active/Stopping transitions.
-- `RegistryDispatcher::handle_fetch` owns framework HTTP routes `/metadata`, `/health`, `/inspector/*`, `/action/*`, and `/queue/*`. Prometheus metrics are process-wide and are never served by core itself; `metrics_endpoint::render_prometheus_metrics()` only backs the NAPI `metrics()` binding and `Registry::prometheus_metrics()` so hosts can mount the rendered response on their own router. TypeScript NAPI callbacks keep action/queue schema validation and queue `canPublish`.
+- `RegistryDispatcher::handle_fetch` owns framework HTTP routes `/metadata`, `/health`, `/inspector/*`, `/action/*`, and `/queue/*`. Prometheus metrics are process-wide and are never served by core itself; `metrics::render_prometheus_metrics()` only backs the NAPI `metrics()` binding and `Registry::prometheus_metrics()` so hosts can mount the rendered response on their own router. TypeScript NAPI callbacks keep action/queue schema validation and queue `canPublish`.
 - Raw `onRequest` HTTP fetches bypass `maxIncomingMessageSize` / `maxOutgoingMessageSize`. Those message-size guards apply only to `/action/*` and `/queue/*` framework routes, not unmatched user `onRequest` paths.
 - Framework HTTP error payloads omit absent `metadata` for JSON/CBOR responses so missing metadata stays `undefined`. Only explicit metadata `null` serializes as `null`.
 

examples/kitchen-sink/scripts/mock-agentic-loop.ts

@@ -11,7 +11,7 @@ pub mod engine_process;
 pub mod error;
 pub mod inspector;
 pub mod inspector_bundle;
-pub mod metrics_endpoint;
+pub mod metrics;
 pub mod registry;
 pub mod runtime;
 pub(crate) mod serde_metrics;

examples/kitchen-sink/scripts/sqlite-memory-soak.ts

@@ -113,11 +113,6 @@ fn ensure_rivetkit_info_recorded() {
 }
 
 fn record_rivetkit_info_inner(info: RivetKitInfo) {
-	// Startup paths reach this from inside the runtime, which is the only place
-	// a handle to sample can be taken.
-	#[cfg(not(target_arch = "wasm32"))]
-	crate::tokio_runtime_metrics::ensure_sampler_started();
-
 	let mut current = CURRENT_RIVETKIT_INFO.lock();
 	if let Some(previous) = current.as_ref()
 		&& previous != &info

rivetkit-rust/packages/rivetkit-core/src/lib.rs

@@ -504,7 +504,7 @@ fn handle_metadata_fetch(
 		&serde_json::json!({
 			"runtime": "rivetkit",
 			"version": env!("CARGO_PKG_VERSION"),
-			"type": crate::metrics_endpoint::runtime_type(),
+			"type": crate::metrics::runtime_type(),
 		}),
 	)
 }

…es/rivetkit-core/src/metrics_endpoint.rs …st/packages/rivetkit-core/src/metrics.rsrivetkit-rust/packages/rivetkit-core/src/metrics_endpoint.rs renamed to rivetkit-rust/packages/rivetkit-core/src/metrics.rs rivetkit-rust/packages/rivetkit-core/src/metrics_endpoint.rs renamed to rivetkit-rust/packages/rivetkit-core/src/metrics.rs

@@ -618,12 +618,14 @@ impl CoreRegistry {
 		shutdown: CancellationToken,
 		on_handle: impl FnOnce(CoreEnvoyHandle) + Send + 'static,
 	) -> Result<()> {
-		crate::metrics_endpoint::record_rivetkit_info(
+		crate::metrics::record_rivetkit_info(
 			config.serverless_package_version.clone(),
 			config.version,
 			"serverful",
 			config.pool_name.clone(),
 		);
+		#[cfg(not(target_arch = "wasm32"))]
+		crate::tokio_runtime_metrics::ensure_sampler_started();
 
 		let dispatcher = self.into_dispatcher(&config);
 		let manage_engine = should_manage_engine(&config.endpoint, config.engine_spawn)?;

rivetkit-rust/packages/rivetkit-core/src/registry/http.rs

@@ -173,12 +173,14 @@ impl CoreServerlessRuntime {
 			config.handle_inspector_http_in_runtime,
 		));
 		let base_path = normalize_base_path(config.serverless_base_path.as_deref());
-		crate::metrics_endpoint::record_rivetkit_info(
+		crate::metrics::record_rivetkit_info(
 			config.serverless_package_version.clone(),
 			config.version,
 			"serverless",
 			config.pool_name.clone(),
 		);
+		#[cfg(not(target_arch = "wasm32"))]
+		crate::tokio_runtime_metrics::ensure_sampler_started();
 
 		Ok(Self {
 			settings: Arc::new(ServerlessSettings {
@@ -374,12 +376,14 @@ impl CoreServerlessRuntime {
 	async fn start_response(&self, req: ServerlessRequest) -> Result<ServerlessResponse> {
 		let headers = parse_start_headers(&req.headers)?;
 		self.validate_start_headers(&headers)?;
-		crate::metrics_endpoint::record_rivetkit_info(
+		crate::metrics::record_rivetkit_info(
 			self.settings.package_version.clone(),
 			self.settings.version,
 			"serverless",
 			headers.pool_name.clone(),
 		);
+		#[cfg(not(target_arch = "wasm32"))]
+		crate::tokio_runtime_metrics::ensure_sampler_started();
 		if req.body.len() > self.settings.max_start_payload_bytes {
 			return Err(IncomingMessageTooLong {
 				limit: self.settings.max_start_payload_bytes,

rivetkit-rust/packages/rivetkit-core/src/registry/mod.rs

@@ -4,8 +4,8 @@ mod common;
 #[path = "integration/counter.rs"]
 mod counter;
 
-#[path = "integration/metrics_endpoint.rs"]
-mod metrics_endpoint;
+#[path = "integration/metrics.rs"]
+mod metrics;
 
 #[path = "integration/sqlite_corruption_fuzz.rs"]
 mod sqlite_corruption_fuzz;

rivetkit-rust/packages/rivetkit-core/src/serverless.rs

@@ -1,14 +1,13 @@
 #[test]
 fn render_prometheus_metrics_includes_rivetkit_info() {
-	rivetkit_core::metrics_endpoint::record_rivetkit_info(
+	rivetkit_core::metrics::record_rivetkit_info(
 		env!("CARGO_PKG_VERSION"),
 		42,
 		"serverful",
 		"metrics-test-pool",
 	);
 
-	let metrics =
-		rivetkit_core::metrics_endpoint::render_prometheus_metrics().expect("render metrics");
+	let metrics = rivetkit_core::metrics::render_prometheus_metrics().expect("render metrics");
 	let body = String::from_utf8(metrics.body).expect("metrics should be utf-8");
 	let expected = format!(
 		"rivet_rivetkit_info{{envoy_kind=\"serverful\",envoy_version=\"42\",pool_name=\"metrics-test-pool\",runtime=\"rivetkit\",type=\"local\",version=\"{}\"}} 1",