Tools: Verification Layer For Browser Agents: Amazon Case Study 2026

How structured snapshots + Jest-style assertions make small local models reliable.

This post is a technical report on four runs of the same Amazon shopping flow. The purpose is to isolate one claim: reliability comes from verification, not from giving the model more pixels or more parameters.

Sentience is used here as a verification layer: each step is gated by explicit assertions over structured snapshots. This makes it feasible to use small local models as executors, while reserving larger models for planning (reasoning) when needed. No vision models are required for the core loop in the local runs discussed below.

Task (constant across runs): Amazon → Search “thinkpad” → Click first product → Add to cart → Proceed to checkout

Screenshot-based agents use pixels as the control plane. That often fails in predictable ways: ambiguous click targets, undetected navigation failures, and “progress” without state change.

The alternative is to treat the page as a structured snapshot (roles, text, geometry, and a small amount of salience) and then require explicit pass/fail verification after each action. This is the “Jest for agents” idea: a step does not succeed because the model says it did; it succeeds because an assertion over browser state passes.

The target configuration is a strong planner paired with a small, local executor, still achieving reliable end-to-end behavior. Concretely: DeepSeek-R1 (planner) + a ~3B-class local executor, with Sentience providing verification gates between steps.

Note on attribution: the run logs included in this post report outcomes (duration/tokens/steps) but do not consistently print model identifiers. Where specific model names are mentioned below, they are explicitly labeled as run configuration.

In other words, the point is not that small models are magically capable; it’s that verification makes capability usable.

These demos use the Sentience Python SDK, Playwright for browser control, and local LLMs for planning/execution. The minimal install sequence is straight from the SDK README:

Source: HackerNews