Ledger

The append-only record every other mechanism reads.

Each model call, tool call, decision, grant, rejection and failure is a TaskEvent with a name and its full body. Tool events follow tool.<name>.requested and tool.<name>.result; approvals use approval.pending_call and approval.executed. The completion gate and judge read the ledger, bench measures from it, --trace renders it, turnstream mirrors it, and a restart resumes from it. A task that waits days for an approval continues by re-driving a turn from what the ledger says.

Decision model

The port every closed question goes through.

Contract

The types a host fills in or implements. They live in agentcontract, toolcontract, model and taskstate, so a host can depend on them without depending on the…