TO2D

Architecture Lab

Reliable AI Systems

Engineering patterns for building reliable real-world software with probabilistic models.

Modern software is beginning to interact directly with real-world systems.

Examples include AI agents navigating websites, browser automation workflows, document processing pipelines, operational tooling that interacts with external APIs, and business systems driven by AI-assisted reasoning.

These systems differ from traditional software in one important way. They operate inside environments whose behavior changes independently of the code.

Websites update. Authentication flows evolve. APIs introduce edge cases. Business processes adapt.

As a result, reliability becomes a systems problem rather than a modeling problem. Improving prompts alone rarely solves it.

Instead, reliable systems separate responsibilities:

environment
↓
AI reasoning
↓
deterministic reliability boundaries
↓
software execution
↓
effects on the environment

This site explores engineering patterns for building systems that remain stable under those conditions.

The ideas here emerged while building automation systems interacting with dynamic environments, where reliability problems appear early and often.

The sections that follow explore the architectural pieces required to make these systems work.

Real-World Software Loop

Real-World Systemswebsites · APIs · documents · humansobserveSoftware Systemworkflows · automation · agentsdecideAI Modelprobabilistic reasoningactActions on External Systemsbrowser actions · API calls · updatesenvironment changes

Reliability Architecture

Real-World EnvironmentInput / TaskAI Model(probabilistic)probabilistic layerReliability Layercontracts · invariants · repair · retrydeterministic boundarySoftware System(deterministic)deterministic systemReal-World Effectsfeedback loopinformation flow ↓

Reliable AI systems are not just model integrations. They are software systems operating in dynamic real-world environments.

Framework