Limits

Normative for every host: dispatch time, guest memory, and payload sizes are bounded, and crossing a bound is an error the caller sees — never a truncation, never a hang. The concrete values are host operations, not something a realm can declare or rely on. The reference host’s defaults:

Setting	Default	Behaviour at the limit
assistant.wasm.enabled	true	false rejects every dispatch with a clear error — the kill switch. Declarative content is unaffected.
assistant.wasm.dispatch-timeout	30s	The dispatch is interrupted and returns an error. Work longer than the budget cannot run on this host.
assistant.wasm.max-memory-pages	1024 (64 MiB)	A module declaring more is rejected with a clear message.
guest I/O	1 MiB per payload	Each of the function’s args, its result, and every host-call request/response is bounded — at 1 MiB or the module’s memory cap, whichever is smaller. Oversized payloads error rather than truncate.

In the reference host, every dispatch is observable: it records the bundle, function, elapsed time, error if any, and how many gateway calls the guest made.