ADR-028's remote_safe/trusted_peer was a parallel, weaker authorization system
that duplicated the existing AccessControl/Identity machinery and couldn't
express the head→N-workers pattern (the primary use case). The flat-namespace
single-peer overlay model (one connection layer in CompositeOperationEnv)
structurally breaks the moment a head has two workers both exposing
/container/exec.
ADR-029 replaces it with:
- Peer-keyed overlays: PeerCompositeEnv { connections: HashMap<PeerId, ...> }
replaces CompositeOperationEnv's singular connection layer. A head node
routes invoke_peer() to the right peer via PeerRef::Specific / PeerRef::Any.
- AccessControl-based peer authorization: the existing AccessControl::check
(peer_identity) gates peer calls — the same mechanism that gates every other
call. remote_safe/trusted_peer/RemoteFilter/list_operations_peer_scoped/
services_list_handler_peer_scoped are retired. The op's AccessControl IS the
peer-authorization policy; no parallel system.
- ScopedPeerEnv: peer-qualified reachability (peer-pinned allowlist) replaces
from_call's namespace_prefix as the disambiguation mechanism. Cross-peer
collision dissolves (separate sub-overlays); same-peer collision stays error.
- services/list-peers opt-in for peer-attributed re-export listing.
POC-validated against real types (scratch module written, type-checked,
removed; build clean, 207 tests pass). Petgraph not needed for v1 (one-hop,
shallow); nested HashMap suffices; extends to multi-hop without redesign (OQ-32).
OQ impact: OQ-25 dissolved (no marking); OQ-28 cross-peer dissolved / same-peer
stays; OQ-26/27/29 stay; new OQ-30 (Any routing policy), OQ-31 (list-peers
semantics), OQ-32 (multi-hop federation).
Research: docs/research/alknet-call-peer-routing/findings.md (POC shapes,
prior art — Ray.io actors, Dapr service invocation, full ADR draft).
ADR-028 marked Superseded; ADR-017 DC-1 amendment updated to point at ADR-029.
