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A session is the record of one run of an agent or harness. A trace is the step-by-step evidence of what happened in that run: model calls, tool calls, tokens, cost, latency, and errors. Together they let you answer what an agent did, not only that it ran.

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Sessions

A session links one run to its subject, the agent or harness that ran it. It holds the run’s outcome and timestamps, its events, and its turns when a transcript was uploaded. A session is a record, not a command. Creating one does not start a run, and an uploaded session is final once created: it cannot be edited or deleted.

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Traces

Traces are OpenTelemetry data. They reach Agent Registry from three sources:
  • Trace plugin for Claude Code: turns each coding session into traces without code changes.
  • atlanai SDK: traces your own agents and their model and tool calls.
  • OTLP exporter: sends traces from any OpenTelemetry setup.
Every trace is stored in your organization, and is accepted only for a workspace your credentials can reach.

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Attribution

Attribution connects a trace to agents, sessions, skills, and versions. What it can connect depends on the identifiers the source sent. Explicit identifiers are evidence. Missing identifiers mean the link is unknown. For skills, the registry matches the skills recorded in a trace to the skill version with the same content. Each match is an exact match, a SKILL.md match, or a name match, from strongest to weakest.

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Where to read them

  • Agent page → Sessions: the recorded runs for one agent.
  • Agent page → Usage → Recent runs: open a run, start with Highlights, then select Full trace for each recorded step.
  • Skill page → Usage: runs attributed to one skill, with their match confidence.

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Example

An engineer installs the trace plugin for Claude Code and fixes a bug with it. The session reaches Agent Registry with its trace. The engineer opens the run from Recent runs and reads Highlights: the prompt, key decisions, errors, and response. Full trace shows each tool call in order.

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What sessions and traces do not prove

  • An accepted request is not a stored result. A successful exporter or API response confirms one step. Find the matching trace in Agent Registry and compare its identifiers and timestamps.
  • Missing fields are unavailable, not empty. A trace without a field is not proof that nothing happened.
  • A name is not a version. Do not infer a skill version from its display name.

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See also