Probe types

`source_type`	Value reported	Status
`prometheus`	scalar from PromQL query	shipped
`http`	response_time_ms	shipped
`tcp`	connect_time_ms	shipped
`dns`	resolve_time_ms	shipped
`tls_cert`	days_until_expiry	shipped
`icmp`	n/a	stubbed
`grpc`	n/a	stubbed
`websocket`	n/a	stubbed
`mtls_http`	n/a	stubbed
`database`	n/a	stubbed

Shipped runtimes

Each shipped runtime has a dedicated guide:

Stubbed runtimes

The cloud accepts metric definitions for stubbed source types and stores their source_config. The agent recognises them but reports not_implemented in the reason field on every probe. The metric remains in no_data until the runtime ships.

Source type	Why stubbed
`icmp`	Most container runtimes need `CAP_NET_RAW` to open raw sockets. The TCP probe is a better proxy for "is this host reachable" in cloud-native environments.
`grpc`	Adds a `@grpc/grpc-js` dependency that is not yet justified by validated demand.
`websocket`	Same: adds the `ws` library for a probe with limited validated demand.
`mtls_http`	Requires a client-cert secret store. The auth model needs design work before runtime work.
`database`	Requires per-driver client libraries and a connection-string secret store.

Common contract

Every source's runtime exports the same interface:

interface ProbeSource<TConfig> {
  validateConfig(config: unknown): null | string;
  execute(config: TConfig, env?: AgentEnv): Promise<ProbeResult>;
}

interface ProbeResult {
  value: number | null;
  timestamp: string;
  status_hint?: "no_data";
  reason?: string;
  metadata?: Record<string, unknown>;
}

Sources never throw. Network errors, malformed config, missing fields all resolve to { value: null, status_hint: "no_data", reason: "<code>" }. The dispatcher applies the threshold rule only when status_hint is absent.