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  1. Cloacina
  2. /
  3. Engine & Primitives
  4. /
  5. Constructors & Providers

Constructors & Providers

Constructors & Providers

A constructor is a reusable, parameterized factory for one of Cloacina’s primitives (task, trigger, accumulator, reactor). You author it once — a struct plus a body — and consumers instantiate it with their own configuration and capability grants. Constructors run WASM-sandboxed, so a consumer decides exactly what the sandbox may reach (files, network, environment) via default-closed grants.

A provider is a suite of constructors: one crate compiles to one WASM component that may expose N members, indexed by a provider.json. A consumer selects a member with constructor = "<name>" and references the provider with from = "<provider crate>".

How it flows

Providers ride Cargo’s dependency model — there is no separate provider registry to operate:

  1. Author a provider crate (cloacina-provider-<name>) with one or more #[constructor] members and one constructor_provider! declaration.
  2. Consume it from a workflow: add the crate as an ordinary Cargo dependency (Rust) or declare it in [metadata.providers] (Python), then reference a member with constructor!(from = "...", constructor = "...") / cloaca.constructor(...).
  3. Build: the compiler discovers the reference, resolves the provider from the dependency graph, builds it to a wasm32-wasip2 component, and bundles it into the workflow package — the deployed artifact is hermetic.
  4. Run: the server (or an execution agent — fleet dispatch is transparent) unpacks the bundled provider at load, resolves the member, binds the consumer’s config, and executes it inside a WASI sandbox scoped exactly to the consumer’s grants.
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