Files
alkcall/docs/architecture/open-questions.md
T
glm-5.3-flash f8dad9dbc8 feat(review 006 Unit 2): additive OperationSpec.description disclosed via discovery (E-02)
- OperationSpec gains description: Option<String> (builder
  with_description, defaults None; no struct-literal construction
  sites exist, so additive by construction)
- spec_to_json_pub emits description when set; rebuild_spec_for
  parses it back — the field survives from_call discovery and
  op/register announcement (same round-trip pattern as
  resource_id_path / publish_schema)
- services/list and the local-ops half of services/list-peers emit
  description when set; output-schema docs on both listing specs and
  operation_spec_schema advertise the field
- Tests: builder/default, emit/omit, listing emission, schema
  disclosure, schema-doc presence, round-trip + absent-stays-absent
  (8 new; 616 total)
- Docs: review 006 Unit 2 marked IMPLEMENTED; ADR-047 §6 amendment
  records the E-02 discovery decision (listing enrichment lands, the
  channel/resources/subscribe half stays deferred); OQ-40 gains the
  load-bearing note; operation-registry.md struct + listing docs;
  CHANGELOG

Verification: cargo test (616 pass), clippy -D warnings (host +
wasm32), fmt --check, cargo doc --no-deps, wasm32 check — all clean
2026-09-06 19:26:51 +00:00

9.3 KiB

status, last_updated
status last_updated
draft 2026-08-12

Open Questions

Open questions are tracked here, organized by theme. Each question has a status, priority, and (when resolved) a resolution citing the ADR.

Status values: open, resolved, deferred(scope), deferred(unclear), partially resolved, dissolved.

Call Protocol

OQ Title Status Priority Resolution
OQ-01 Call protocol scope within a connection resolved medium ADR-015 — stream model, multiplexing
OQ-02 Operation path format and routing scope resolved medium /{service}/{op} is the correct design
OQ-03 Batch operation semantics resolved low Correlated call.requested events
OQ-04 Session-scoped operation registries resolved medium ADR-019 — OperationEnv trait layering
OQ-05 Abort cascade semantics for nested calls resolved high ADR-020
OQ-06 Privilege model and authority context resolved high ADR-017
OQ-07 Handler identity registration path and composition authority resolved high ADR-018
OQ-08 Operation error schemas resolved high ADR-016
OQ-09 Safe vault operations for call protocol exposure resolved high ADR-010 — none exposed
OQ-10 Remote-safe marking shape dissolved medium ADR-024 — remote_safe/trusted_peer retired
OQ-11 OperationAdapter error type (AdapterError variants) resolved medium DiscoveryFailed, SchemaParse, Transport, Unauthorized, SamePeerCollision
OQ-12 from_call re-import trigger resolved low ADR-028 — manual free function
OQ-13 from_call namespace collision resolved low Same-peer = error; cross-peer dissolved (ADR-024)
OQ-14 CallClient TLS client-auth resolved high quinn client-auth; key-type-aware verification
OQ-15 PeerRef::Any routing policy resolved low Insertion-order first-match
OQ-16 services/list-peers re-export semantics resolved low Opt-in; services/list is own-ops-only
OQ-17 Multi-hop federation deferred(scope) low One-hop model is the commitment; multi-hop is a feature extension
OQ-18 PeerId — crypto identity vs stable logical id resolved high ADR-025 — PeerId = Identity.id (stable)
OQ-19 Persistent peer registry resolved medium ADR-025 — core trait + in-memory default; persistence adapters separate
OQ-20 API key asymmetry dissolved medium PeerEntry supports multiple credential paths
OQ-21 X.509 outgoing-only case resolved medium Three remote roles; PeerEntry asymmetry correct

Call Protocol — Pub/Sub

OQ Title Status Priority Resolution
OQ-22 Call protocol pub/sub primitive — pub to go with sub partially resolved high ADR-046 resolves the primitive: OperationType::Pub + HandlerKind::Sink + call.published wire event + invoke_sink() dispatch path. The fan-out/broker mechanism (one producer, N consumers, topic matching) is deferred to the channels session — the call protocol is point-to-point; the broker is a routing concern that sits above it. ADR-047 §1 names the broker (Gap B) as out-of-scope for alkcall; the hub composes it on top of the Pub/Sub primitives. See §"Pub/Sub Gap" below.

Pub/Sub Gap

The call protocol's StreamingHandler / invoke_streaming() path (ADR-021) is point-to-point: a call.requested arrives, the handler produces a stream of call.responded events back to that one caller. There was no mechanism for a producer to stream data to a responder (producer→consumer streaming), and no fan-out (one producer, N consumers).

ADR-046 resolves the directional gap: OperationType::Pub is the producer→consumer streaming complement to Sub (was Subscription, renamed for symmetry). HandlerKind::Sink is the consuming handler type. call.published is the wire event carrying stream chunks. invoke_sink() is the dispatch path. CallConnection::publish() is the client method. The Subscription variant is renamed to Sub (wire string "sub").

Fan-out deferred. The broker (topic registry, PubSub matching, N-consumer fan-out) is deferred to the channels session. The call protocol is point-to-point (one initiator, one responder, a stream between them); a topic registry that outlives individual calls is a different lifecycle and a different concern. The broker's first consumer is the channels channel/resources/subscribe operation (ADR-037) and the hub-as-broker pattern (ADR-042). The Pub primitive is the load-bearing piece the broker composes on.

Channels

OQ Title Status Priority Resolution
OQ-23 Full channel-level flow-control windowing deferred(scope) low Bounded-buffer decided (ADR-040); full windowing blocked on HOL-blocking deployment observation
OQ-24 Channels add/strip API shape open low Whether the 8-byte header add/strip is built into the read/write path or a standalone utility. The contract (ADR-035) is decided; the function surface is not
OQ-31 channel/open ACL granularity resolved high ADR-047 — channel/open dissolves into per-ALPN ops; each op has its own access_control
OQ-32 Quota lifecycle (opener vs closer, transport drop) resolved high ADR-047 §7 — the per-connection opener ledger; decrement on every teardown path, keyed by opener
OQ-33 Per-identity connection cap (endpoint layer) deferred(scope) low Named as a separate layer (ADR-047 §"ALPN category reframe" references the findings); belongs at alknet-endpoint, not channels. Named to stop the re-tangle
OQ-34 channel_open marker wire format resolved medium ADR-047 §2 — boolean "channel_open": true in services/schema; ALPN derivable from op name
OQ-35 OperationEnv::channel_manager() coupling resolved high ADR-047 §4 — extension trait ChannelOperationEnv in channels-call; call crate stays free of channels types
OQ-36 channel_id allocation in Pub case resolved medium ADR-047 §5 — "connection owner allocates" (the side that holds the ChannelManager); amends "responder allocates"
OQ-37 from_call relay wrapper for marked ops open medium ADR-047 §1 names it as a consumer (hub) concern; alkcall's from_call reconstructs the marker (Gap F resolved) so the consumer can branch on it
OQ-38 ALPN→path-segment mapping resolved low ADR-047 §"Negative" — strip the alk/ prefix; ALPNs without that prefix use the full ALPN string (rare, two-way-door)
OQ-39 channel/control control-handle surface open medium The channel/control handler currently returns channel:control_not_implemented. The control-handle surface (per-channel control callbacks registered by ALPN crates, routing message to the handler's control handle for channel_id) is real design work — each ALPN crate needs a way to register a control callback, and the channels layer needs a control-handle registry keyed by channel_id. Deferred until an ALPN crate (TTY, tunnel) needs out-of-band control.
OQ-40 channel/resources/subscribe live subscription open medium The channel/resources/subscribe handler currently returns channel:resources_not_implemented. The live subscription aggregated from ALPN-crate resource enumerators (ADR-047 §6) requires each ALPN crate to provide a resource enumerator, and the channels layer to aggregate them into a live Stream that emits on any change. The current stub is a one-shot error; the real implementation is deferred until a consumer (hub, dashboard) needs live resource discovery. Load-bearing for alktunnels' discovery UI (review 006 E-02): a consumer cannot distinguish produced tunnel resources by op name alone. The static half is covered (0.5.0: OperationSpec.description on services/list — describes the op, not the live resource set); the dynamic half stays deferred — alktunnels v1 uses config-known op names.
OQ-41 QUIC-native multi-stream substrate open medium Only the in-line substrate mode is implemented (single bidi stream, header-demuxed N channels). The QUIC-native multi-stream substrate (accept remaining bidi streams, read headers off each — ADR-034 §substrate modes) is deferred to the downstream alknet crate. The wire format and demux loop are correct for both substrates; only the outer accept_bi() loop is missing. The alknet crate owns the QUIC dial/accept loop and is the natural place for the multi-stream accept loop. This crate stays transport-agnostic (no QUIC dependency, WASM-compatible).

Core Types

OQ Title Status Priority Resolution
OQ-25 BiStream type definition resolved high ADR-005 — trait, Connection parameter
OQ-26 AuthContext resolution timing resolved high ADR-003 — hybrid resolution
OQ-27 ALPN string naming convention resolved medium ADR-004 — alk/ prefix
OQ-28 Dynamic handler registration resolved low ADR-019 — curated static, overlays dynamic
OQ-29 Handler-level auth resolution observability resolved medium set_identity() on Connection for observability
OQ-30 Dynamic resource ownership resolved high ADR-011 — OwnershipProvider, resource_id_path