Files
alkcall/docs/architecture/open-questions.md
T
glm-5.2 bfb265e31b fix: Unit 6 — convention + doc cleanup (C-09, C-20-rem, C-22-rem, C-24, P-10, P-11)
Conventions satisfied, `cargo doc` clean, no actively-wrong comments,
producer/consumer naming consistent in the call/registry docs.

P-10 — `pump_sink` matched the string literals "call.published",
"call.completed", "call.aborted" (dispatch.rs) instead of the
EVENT_PUBLISHED / EVENT_COMPLETED / EVENT_ABORTED constants the rest
of the file imports. Replaced with the constants — pure refactor
hazard, no behavior change.

C-20 remainder — the wrong "SAFETY:" comment at from_call.rs:271
marked no `unsafe` block and was factually wrong (described a `'static`
return that isn't what `derive_alpn_from_op_name` does — it returns
`Option<String>`; the leak happens in `leak_alpn`). Reworded to a
plain note about the `'static` lifetime requirement. Also reworded
the abort-cancels claims in the `pump_sink` and `pump_stream` doc
comments (dispatch.rs): both claimed `call.aborted` "cancels the task
and drops the handler future" — the handler is actually `join!`-ed to
completion and not yet cancelled (the abort-cancels-Pub mechanism is
review 001 Unit 9). Trimmed step-numbered narration comments in
adapter.rs / client.rs that restated what the code does, keeping the
ordering-constraint and REQ-CH comments. The big reassembly.rs
deliberation landed with Unit 4; this finishes the remainder.

C-09 — fixed the 2 remaining `cargo doc` warnings (was 4; the
register_openable links were fixed in Unit 3):
- `unresolved link to default_policy` (operations.rs:50) — the
  [`default_policy`] intra-doc link resolves to
  super::policy::default_policy; used the full path.
- `env is both a module and a macro` (channels/mod.rs:30) — the
  [`env`] link collided with the std `env!` macro; qualified as
  [`self::env`].
`cargo doc --no-deps` now emits 0 warnings.

C-22 remainder — removed the filler `PhantomData` test at client.rs
(`let _ = std::marker::PhantomData::<ChannelClient>;` — asserts
nothing). The env.rs tautology was already removed in Unit 3.

C-24 — replaced "client→server streaming" with "producer→consumer
streaming" in call-protocol.md, operation-registry.md, README.md, and
open-questions.md (4 occurrences). Per AGENTS.md §8 the convention is
producer/consumer, not server/client. The remaining "client→server"
references in channels ADRs 034/037 are in stream_type table contexts
that Unit 10 (C-26) will handle as part of the spec-doc renumbering.

P-11 — amended ADR-046 §3's SinkHandler type so the stream item type
matches §6. §3 declared `Pin<Box<dyn Stream<Item = Value> + Send>>`;
§6 declared `Pin<Box<dyn Stream<Item = Result<Value, CallError>> +
Send>>`. The code uses §6's shape uniformly (registration.rs:32-40,
aliased as PublishStream). §3's text and the Door-type section are
amended to match §6; the Door-type section already marked the concrete
stream item type a two-way-door detail, so this is a text correction,
not a design change. Added an amendment note dated 2026-08-13.

Verification:
- cargo test --lib         → 449 passed, 0 failed (was 450; -1 removed filler test)
- cargo clippy --all-targets -- -D warnings → clean
- cargo fmt --check        → clean
- cargo doc --no-deps      → 0 warnings (was 2)
2026-08-13 08:47:20 +00:00

95 lines
7.3 KiB
Markdown

---
status: draft
last_updated: 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, `Pub`↔`Sub` 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 `alknet/` prefix; ALPNs without that prefix use the full ALPN string (rare, two-way-door) |
## 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 — alknet/ 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 |