Agent execution substrate

Definition

The isolated, stateful environment in which agents observe and act, including compute, filesystem, browser, network, credentials, resource limits, and session lifecycle. The workspace, browser, shell, network, and identity are part of the agent—not background infrastructure.

Sandboxing is established; agent-specific substrates are still taking shape.

Why it matters

The workspace, browser, shell, network, and identity are part of the agent—not background infrastructure.

The operating shift is from “Run the model somewhere” to “Engineer the place where action occurs.”

System anatomy

Practice 1

Isolate work by task and identity

Practice 2

Constrain network, secrets, and resource use

Practice 3

Capture environment transitions as evidence

Important distinctions

Run the model somewhere

This concept moves the engineering system toward engineer the place where action occurs.

Implementation signals

• Isolate work by task and identity
• Constrain network, secrets, and resource use
• Capture environment transitions as evidence

Failure modes

• Hidden environmental side effects
• Shared credentials and unbounded egress

Sources and further study

1. Google Cloud — Agent Sandbox on GKE and Agent Substrate

   An agent-specific execution architecture emphasizing isolation, state, scheduling, and environment control.

   Use in this library: First-party case study. This first-party account documents one organization, product, or implementation context and should not be generalized without local evidence.

   engineering · engineering · Published 2026-05-20
2. OpenAI — Harness engineering: leveraging Codex in an agent-first world

   A production case study in designing repositories, tools, feedback loops, and environments for agent-first delivery.

   Use in this library: First-party case study. This first-party account documents one organization, product, or implementation context and should not be generalized without local evidence.

   engineering · engineering · Published 2026-02-11
3. OWASP GenAI Security Project — OWASP Top 10 for Agentic Applications 2026

   A threat-oriented reference for goal hijacking, tool misuse, identity abuse, memory poisoning, and cascading agent failures.

   Use in this library: Official guidance. Guidance describes recommended practice; citation does not prove that a control is implemented or effective in a particular environment.

   guidance · guidance · Published 2025-12