Hierarchical Effects

Planned: io.fs.read, io.fs.write, net.http, net.ws — fine-grained sub-effects that compose hierarchically. Currently all sub-effects collapse to the parent effect token.

These sub-effects are refinements within the canonical six (io, net, clock, gpu, model, rand) — io.fs refines io (io.fs ⊑ io), not a new top-level effect. The taxonomy stays locked at six atoms (compiler/src/effect_taxonomy.sfn); declaring the bare atom ![io] keeps the broadest grant and subsumes every io.* requirement, so existing annotations stay valid unchanged.

The owner-approved model — dotted-name representation, the subsumption rule (io.fs ⊑ io), capsule-manifest interaction, and the G6/G7 implementation gating — is specified in the RFC: docs/proposals/0017-hierarchical-effects.md.