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The Constal model

Understand the small Agent language and strict runtime model that make long-running Agent systems durable, governable, and inspectable.

An Agent should be a small durable program, not a framework-shaped process. Constal gives that program seven compositional primitives and places execution, authority, effects, recovery, and durable truth outside the disposable process that happens to be running it.

Five laws

  1. Durable records are truth. An execution is an attempt. The journal, ledger, Handles, and recorded effects determine what happened and what may happen next.
  2. Agents use seven words. turn, ledger, commit, await, and spawn govern judgment over time. map and reduce govern volume.
  3. The world is made of Resources. Models, APIs, databases, memory, browsers, sandboxes, and storage are authorized and journaled Resource operations with explicit effect and recovery semantics.
  4. Authority is explicit and immutable. Identity, Policy, Resources, Tools, and executable revisions are pinned. Changes occur at defined safe points or through explicit immediate controls.
  5. History is append-only; observation is downstream. Branching, truncation, compensation, steering, and controls append events. Analytics observes orchestration but never becomes orchestration authority.

One coherent system

text
canonical event → Agent language → journaled Resource effects → durable facts
                         ↓                         ↓
                   pinned Policy           declared recovery
                         ↓                         ↓
                    active Run  ← authoritative ledger and workflow state

This separation is the point. Agent code expresses judgment and composition. Resources express capabilities. Policy expresses authority. The runtime owns durability and recovery. The ledger records truth. Channels translate communication, while Credentials remain opaque to Agent code.

Continue with The seven Agent primitives, then see From primitives to production for complete Agent architectures built from them.