OpenTelemetry Event Sink

This is the shared mapping for a native OpenTelemetry event sink. It is an optional adapter contract, not a new Core wire state machine, sampler, collector, or delivery guarantee.

Boundary

• Each Core event maps to one OTLP span named praxo.<event.type>.
• The sink may use an OpenTelemetry SDK or emit OTLP/HTTP JSON through a caller-supplied transport. The Core does not require the OpenTelemetry SDK.
• Event data is excluded by default. A caller may allowlist individual keys.
• Session and run identifiers are exported when present; use opaque identifiers and restrict access to the telemetry backend.

OTLP/HTTP JSON

POST {endpoint} with content-type: application/json. A typical endpoint is http://127.0.0.1:4318/v1/traces.

{
  "resourceSpans": [
    {
      "resource": {
        "attributes": [
          {"key": "service.name", "value": {"stringValue": "praxo-core"}}
        ]
      },
      "scopeSpans": [
        {
          "scope": {"name": "praxo-core"},
          "spans": [
            {
              "traceId": "0123456789abcdef0123456789abcdef",
              "spanId": "0123456789abcdef",
              "name": "praxo.tool.call",
              "kind": 1,
              "startTimeUnixNano": "1794294000000000000",
              "endTimeUnixNano": "1794294000000000000",
              "attributes": [
                {"key": "praxo.event.type", "value": {"stringValue": "tool.call"}},
                {"key": "praxo.session.id", "value": {"stringValue": "s1"}},
                {"key": "praxo.run.id", "value": {"stringValue": "run-123"}},
                {"key": "praxo.event.at", "value": {"stringValue": "2026-11-10T07:00:00Z"}}
              ]
            }
          ]
        }
      ]
    }
  ]
}

• Identifiers are hexadecimal strings: 16 bytes for traceId, 8 bytes for spanId.
• startTimeUnixNano and endTimeUnixNano are Unix nanoseconds. One span represents one event, not the duration of a complete run.
• Empty session/run identifiers and zero timestamps are omitted.
• Allowed data keys become praxo.event.data.<key> string attributes. Selecting a key does not redact its value.

Transport Seam

Implementations without the OpenTelemetry SDK may accept a caller-supplied transport with the HTTP request method, URL, headers, and body. The transport returns a status code and a bounded response body. A 2xx status is success; any other status is an error containing the status and a bounded body.

Baseline Status

The canonical per-language list is the adapter status table. Go maps events through adapters/otel and a trace.Tracer. Python, TypeScript, Java, Rust, R, C#, Ruby, PHP, Elixir, Lua, C, C++, Fortran, Haskell, OCaml, Swift, Dart, Perl, D, Delphi/Free Pascal, Objective-C, Nim, V, Zig, Julia, MATLAB/Octave, Erlang, and COBOL provide transport-seam sinks over a caller-supplied OTLP/HTTP transport. Other implementations do not have an in-tree OTel sink yet. All current implementations use deterministic fixtures or an in-memory exporter in tests; no live collector, sampling policy, or vendor backend is claimed.

Testing

Use an in-memory exporter or an injected transport. Required assertions: span name, trace/span identifier shape, start and end timestamps, session/run attributes, default data exclusion, explicit allowlist behavior, 2xx success, and non-2xx error.