Run-record observability outputs

Harn persists the projections it computes while an agent runs. Observability consumers should read these fields instead of parsing assistant text or reconstructing spans from cumulative usage totals.

Span tree

Workflow run records expose completed spans in trace_spans. Each span has a stable span_id and optional parent_span_id; joining those fields produces the authoritative tree. LLM spans also expose ttft_ms when Harn observed a first response token.

{
  "trace_spans": [
    {
      "trace_id": "trace_...",
      "span_id": 8,
      "parent_span_id": 3,
      "kind": "llm_call",
      "name": "llm_call",
      "start_ms": 120,
      "duration_ms": 900,
      "ttft_ms": 125,
      "metadata": {}
    }
  ]
}

start_ms is relative to the run's tracing epoch. duration_ms and ttft_ms are monotonic durations. Root spans set parent_span_id to null; spans without an observed first token omit ttft_ms.

Run records written before this schema used parent_id. Harn still accepts that name when loading historical records, while newly persisted records use parent_span_id.

Per-turn parsed output

Every model response is appended as a provider_call_response event on the agent.transcript.llm topic in .harn/events.sqlite. In addition to the raw response text, the event includes:

parsed_tool_calls: Harn's normalized tool-call parse. Provider-native calls take precedence; otherwise this contains calls parsed from Harn's text tool protocol, including the legacy name({...}) form.
loop_state: a decoded object when the response contains a complete ## LOOP_STATE / ## END_LOOP_STATE block. Booleans, numbers, null, and nil become JSON primitives; other values remain strings. The field is null when no complete block exists.
tool_calls: the provider-native receipt only. It can be empty even when parsed_tool_calls contains text-protocol calls.

These projections are redacted by the same transcript policy as text before they reach SQLite. Correlate a response with its request and related records by call_id; iteration identifies its agent-loop turn and span_id links it to the run-record span tree.

Consumers that need the whole timeline should read the event-log topic in event order. They do not need the optional llm_transcript.jsonl debug sidecar.