Effects and idempotency

AGL 0.4 makes operational capabilities visible to the compiler. Types describe data; effects describe what executing a task may do.

language "0.4";

task publish(id: String, article: String) -> String
  effects [network, external_write]
  idempotency keyed_by id {}

pipeline release(id: String, article: String) -> String
  effects [network, external_write] {
  let publication = publish(id, article) retries 2;
  return publication;
}

Built-in effects

Effect	Meaning
model	Calls a generative model
network	Uses the network
filesystem	Reads or writes host files
external_read	Reads external state
external_write	Mutates external state
secret	Reads secret material
human	Suspends for human input or approval

Applications may introduce capability names for deployment policy. Custom names do not weaken built-in rules.

Pipeline effects are transitive through task, agent-tool, and pipeline calls. An omitted pipeline clause is inferred. When a pipeline declares effects [...], the list is an allowed ceiling and missing capabilities are a static error.

Retry safety

pure, idempotent, keyed_by, and non_idempotent document whether repeated execution is safe. A retried external write must be idempotent or keyed. The key parameter must be a String.

retry_on remains orthogonal: it selects which typed domain errors cause another attempt, while idempotency determines whether another attempt is safe at all.

See Retries, invocation identity, and budgets for backoff, stable keys, usage accounting, and scoped limits.