Every step, logged. Every step, attributed.
Observability is not a plugin you add after your agents start failing in production. It is the default behaviour from the first run.
Four primitives, all on by default.
A full record of every state transition in every agent run. Each entry includes the agent identity, step index, input state, output state, timestamp, and the policy evaluation that permitted the transition. Immutable. Replayable.
Subscribe to any agent event without modifying agent code. Hooks attach at the SDK layer — you can stream events to a log aggregator, trigger alerts, or feed a metrics sink without touching the agent implementation.
Every prompt is a versioned artefact. When a prompt changes, a new version is created. Every agent run records which prompt version it used. Diff two versions and see exactly how behaviour changed.
Token usage tracked per step, per agent, per run. Not just the total — each step records its own input and output token counts. You can attribute cost to the exact step, not just the endpoint call.
Three things you can do that you cannot do with logging middleware.
Middleware can tell you something happened. Agiorcx can tell you what state the agent was in before it happened, what decision permitted it, which prompt version produced the output, and what it cost — at the step level, not the run level.
Replay any run exactly
Because every state transition is logged before it executes — including the prompt version, the input, and the policy decision — any run can be replayed deterministically. You are not reconstructing what happened from scattered logs. You are replaying a recorded sequence.
Diff prompt versions and see behaviour changes
When a prompt changes and behaviour changes with it, you need to know which change caused which effect. PromptLayer ties every run to a prompt version. Run the same input against v3 and v4 of a prompt and compare step-by-step outputs. Not a guess. A diff.
Attribute token cost to the exact step
Most logging middleware can tell you that a run cost 12,000 tokens. Agiorcx can tell you that step 3 of 7 — the synthesis step — accounted for 8,400 of them. That is the difference between a cost report and a cost optimisation signal.
You opt out of observability. Not into it.
Every agent built on the SDK emits StepAuditLog entries from the first run. There is no configuration step, no SDK wrapper to add, no logging provider to set up. Observability is the default. If you want to disable it for a specific run, you explicitly opt out.