V2 specs tour

The upstream OpenCode contracts underneath doc.haus: who owns what, how sessions admit and execute prompts, how tools are built and bounded, and the two accepted decisions on events and provider policy.

Laws

Single execution: Tool.make(config) can execute only config.execute.
Codec boundary: a tool observes decoded input; Code Mode observes the validated encoded output; model content and metadata come from the tool response.
Canonical representation: a completed call has exactly one stored model representation; a failed call has exactly one stored error plus at most one final partial snapshot. Every other view is derived at a named boundary.
Metadata opt-in: absent response metadata produces absent metadata, never a copied output.
Durable identity: invocation-owned records use the exact Session, agent, assistant message, and call IDs supplied by the runner.
Scoped registration: closing a Scope removes exactly its registration and reveals any prior active overlay.
Captured execution: a call executes the registered tool advertised in its model request.
Per-call rejection: rejecting one unavailable call cannot fail another call.
Storage encapsulation: domain output does not change according to model-output bounding or retention policy.