resource_composition

Declarative resource composition contracts (oka ADR-0026): typed immutable component graphs, validated and explained before any side effect; first-class readiness declarations with budgets; typed output promises (OutputRef<T>) between components; lifecycle events with terminal causes; and a ResourceProvider seam with declared capabilities. Zero package dependencies, vendor-neutral by design (consumers must not import oka).

Design laws:

• Compose small const values by constructor injection; never mutate a graph by string key.
• validate() / explain() are pure — providers are never contacted.
• An unready component never satisfies a dependsOn edge; on readiness timeout the runner cancels the start and awaits it (never Future.timeout over a live child), then tears down in reverse order, never masking the original failure.
• Probe mechanics, protocol semantics, and stop ladders stay in providers; oka's oka_core process seam (tree-aware stop, bounded runs, identity) is the reference adapter.
• Death carries a terminal cause (exited, signaled, killedOnDeadline, providerFault, transportLost, unknown); unknown is never silently upgraded — report-never-guess.

See docs/decisions/0026-declarative-resource-composition-sdk.mdx, docs/guides/resource_composition_plan.mdx, and the R0 survey evidence in docs/evidence/process-lifecycle-r0-survey-2026-09-27.mdx.