The Control Plane is what an operator sees and touches: a live canvas of the running workflow, a signal channel back to the engine, and per-step inspection with the evidence attached. It is a view, deliberately — the Evidence Ledger is the source of truth, and the canvas renders the event stream as it happens.
The canvas
| Property | Semantics |
|---|---|
| Source | The ledger's event stream — not a parallel state store |
| Rendering | Live: each event updates the step's node on the canvas |
| Content | Per step: state, attempts, escalations, verdicts, critique, artifact refs |
| Degradation | A canvas outage stops nothing; gates stay parked until signals return |
The canvas shows what the ledger says, when the ledger says it. There is no operator action that mutates workflow state directly — the only path back into the engine is the signal channel.
The signal channel
Evidence Ledger ──events──▶ Control Plane ──renders──▶ canvas
Operator ──signal──▶ Control Plane ──forwards──▶ engine
│
└─ every signal lands in the ledger| Direction | Carries |
|---|---|
| Inbound | Telemetry: every event, as it happens |
| Outbound | HITL signals: response classes defined in HITL gates |
Every outbound signal lands in the ledger as an event. An operator's decision is evidence, same as a policy evaluation — the audit trail includes the humans.
Per-step inspection
| Field | Available to the operator |
|---|---|
| Identity | step_id, action type, dependencies |
| Progress | State, attempt count, iteration count |
| Governance | Policy decisions with context, verification verdicts with critique |
| Budget | Escalations issued, regeneration count, budget remaining |
| Evidence | Artifact refs — resolvable to content by checksum |
| Diagnosis | On failure or park: the signature and the consumed-inputs digest |
What operators can and cannot do
| Operators can | Operators cannot |
|---|---|
| Resolve parks through response classes | Force a step to commit past a failed verdict |
| Provide data, instructions, or gap acceptance | Override a Cedar DENY |
| Reject a step's goal — routing to compensation | Edit ledger history or sealed artifacts |
| Inspect any step's full evidence | Restart outside the checkpoint discipline |
The two columns are the same property stated twice: the operator participates through the defined signal classes, and every signal is subject to the same gates as everything else. Governance applies to the humans, not just the agents.