Commitment Gate (Harness Engineering)
A commitment gate is a verification checkpoint between an agent producing a candidate output and that output being “locked in” — emitted as a final answer, written to disk, or used to call an irreversible tool. Instead of running skills along a fixed script and fusing results at the end (where errors propagate silently into late fusion), a harness with commitment gates pauses at each commit point, runs relative checks, and either lets the result through or triggers a targeted recovery loop.
Canonical formulation (Affordance Agent Harness)
A-Harness gates commitments with three relative checks:
- Cross-skill agreement — do independent skills/tools converge on the same answer? Disagreement signals underdetermined evidence, not noise to average away.
- Cross-scale stability — does the answer hold under perturbations of scale, framing, or granularity? Brittleness usually means the model latched onto a spurious feature.
- Evidence sufficiency — is there enough grounding to commit, or is the agent extrapolating?
A failed gate doesn’t kill the trajectory — it routes back to the planner/router to gather more evidence, retry a different skill, or escalate. Errors become control-flow signals at the gate, not silent corruption that a final judge has to untangle later.
Where it sits in the harness vocabulary
- Phase gates (e.g. in Plan-Execute-Verify loops) fire at workflow boundaries — coarse-grained.
- Commitment gates fire at every point where the agent would otherwise burn down optionality — fine-grained.
The two compose: PEV gives you outer phase structure, commitment gates enforce verification within a phase before any irreversible step.
Analogies for backend / infra mental model
- The agent equivalent of a CI check that blocks merge.
- A Temporal activity that won’t transition state until a precondition holds.
- A deterministic outer-harness constraint enforcing what the probabilistic inner model can’t guarantee on its own.
Why it matters
LLM compliance with instructions is probabilistic, not deterministic. Commitment gates are the deterministic outer layer that turns probabilistic reasoning into dependable action by refusing to commit on weak evidence and forcing targeted retries instead of silent failure propagation.
References
- Affordance Agent Harness: Verification-Gated Skill Orchestration (arXiv) — origin of the three-check formulation.
- Augment Code, Harness Engineering for AI Coding Agents — broader harness-engineering framing, deterministic outer constraints vs. probabilistic inner model.
- Adnan Masood, Agent Harness Engineering — The Rise of the AI Control Plane — PEV phase-gate context.