Overview

A Hustle is an immutable, bounded auxiliary inference definition. Harness facilities use registered definitions for focused work such as transcript compaction or permission review. It is not a conversational Loop, a delegated agent, or a general task queue.

When to use

Application code configures a Hustle through the facility that needs it. There is no public generic execution method for an arbitrary definition. Register immutable definitions on the Rig, then invoke a supported operation such as Session.Compact.

Proof: Hustle definition boundary and session contract tests.

Configure a Hustle

compactor, err := hustle.Define(
	hustle.WithName("context.compact"),
	hustle.WithParticipation(hustle.ParticipationBlocking),
	hustle.WithTimeout(5*time.Second),
	hustle.WithLimits(hustle.Limits{
		InputBytes:  1024 * 1024,
		OutputBytes: 1024 * 1024,
	}),
	hustle.WithCurrentLoopModel(),
	hustle.WithSystemPrompt("Summarize the earlier conversation.", "v1"),
	hustle.WithPolicyRevision("v1"),
)
if err != nil {
	return fmt.Errorf("define compaction hustle: %w", err)
}

runtime, err := rig.Define(
	rig.WithLoops(assistant),
	rig.WithPrimers("assistant"),
	rig.WithSessionStore(sessions),
	rig.WithHustles(compactor),
	rig.WithHustleLimits(rig.HustleLimits{
		BlockingConcurrent: 1, BlockingQueued: 2,
		BackgroundConcurrent: 1, BackgroundQueued: 2,
		AuditTimeout: time.Second, FinalizationTimeout: time.Second,
		WorkerDrainTimeout: time.Second,
	}),
)
if err != nil {
	return fmt.Errorf("define rig: %w", err)
}

WithCurrentLoopModel resolves the originating Loop’s current model for each run. WithNamedInference instead freezes a dedicated client and model into the Hustle definition.

Proof: definition options and Rig Hustle registration.

Lifecycle

Blocking and background definitions use separate bounded lanes. A supported facility binds the definition, validates input, owns a RunID, persists an internal HustleStarted record, admits the run, resolves inference, validates bounded output, persists exactly one internal terminal event, and finalizes once. Session shutdown closes admission, cancels active work, drains owned invocations, and only then tears down loop runtimes and resources.

Proof: Hustle runtime ownership and lifecycle tests.

Restore and observation

HustleStarted, HustleCompleted, and HustleFailed are internal-visibility audit records. Correlate them by RunID through the internal audit path, not an ordinary public Session event stream. Restore folds those records but does not recreate an interrupted queue, worker, request, or finalizer. An unmatched start is retained as interruption evidence and the restored Session receives a fresh controller.

Proof: Hustle audit events, restore folding, and restore tests.

Source and proof

• Hustle public definitions
• Hustle Rig options
• Internal lifecycle audit
• Session Hustle binding