Files
alkcall/docs/architecture/README.md
glm-5.2 f305f8c0a5 feat: implement channels protocol + ADR-047 (openable ALPNs are operations)
ADR-047: the unifying decision that  dissolves into
per-ALPN ops (, ) with a
 marker on . Each openable ALPN registers
its own ops with their own , ,
, and the marker. The  field is replaced
by  (Sub/Pub). The generic ops (channel/close,
channel/control, channel/resources/subscribe) stay, keyed by
channel_id. Resolves Gaps A-G from the research findings (Gap B broker
named out-of-scope for alkcall; Gap C relay wrapper is consumer
concern; Gap D connection-owner allocates; Gap E extension trait;
Gap F boolean marker on wire; Gap G ACL/ownership complementary).

ADR-037 amended:  dissolves;  removed; generic
ops stay;  preview dropped from resources/subscribe.

Spec docs updated: channel-operations.md (unified model, opener ledger,
ACL flow), operation-registry.md (channel_open marker, ChannelOpenSpec),
README.md (ADR-047), open-questions.md (OQ-31..38 resolved).

Source changes:
- spec.rs: ChannelOpenSpec struct, channel_open field on OperationSpec,
  with_channel_open builder, 3 tests
- discovery.rs: spec_to_json emits channel_open boolean,
  operation_spec_schema includes channel_open, 2 tests
- from_call.rs: rebuild_spec_for parses channel_open marker,
  derive_alpn_from_op_name helper, 6 tests

Channels module (src/channels/, 10 files, ~2400 lines):
- wire.rs: 8-byte chunk header (ChunkHeader, parse/write_header,
  read_header/write_chunk/write_eof async helpers), 12 tests
- reassembly.rs: MpscRecvStream (tokio::mpsc::Receiver<Bytes> →
  AsyncRead), MpscSendStream (AsyncWrite → tokio::mpsc::Sender<Bytes>),
  REQ-CH-01 shutdown sentinel, REQ-CH-02 sender-drop EOF, 10 tests
- mux.rs: MuxHandle (clone-able, register(channel_id)),
  MuxRunner (per-channel pump tasks, exits when handles drop),
  OpenerLedger (ADR-047 §7), 4 tests
- manager.rs: ChannelManager (channel map, open_channel,
  install_channel_zero, route_payload, teardown_channel, clear_all),
  11 tests
- source.rs: ChannelBidiStreamSource (yield-once accept_bi),
  channel_source helper, 4 tests
- adapter.rs: ChannelsAdapter (ProtocolHandler for alknet/channels,
  demux loop, install_channel_zero hook), 1 test
- operations.rs: ChannelOperations (registers channel/close,
  channel/control, channel/resources/subscribe), ChannelCore
  (check_open/on_close wrappers), 4 tests
- policy.rs: ChannelLifecyclePolicy trait, NoCap, PerIdentityChannelPolicy
  (default 256, per_identity_caps override), default_policy, 8 tests
- env.rs: ChannelOperationEnv extension trait (ADR-047 §4),
  ChannelsSessionEnv impl, 2 tests
- client.rs: ChannelClient (from_connection, call_open_op,
  take_call_connection), 1 test

Verification: 432 tests pass (66 new channels + 10 marker + 356
existing), clippy clean, fmt clean, cargo doc generates.

Cargo.toml: +bytes dependency.
2026-08-12 12:13:53 +00:00

12 KiB

status, last_updated
status last_updated
draft 2026-08-12

alkcall

The call + channels RPC crate. Structured JSON RPC (operations, streaming subscriptions, service discovery) and N-channel multiplexing over one transport stream (channel 0 pre-negotiated as alknet/call).

This crate unifies alknet-call and alknet-channels from the alknet mono-repo, plus the vendored core types formerly in alknet-core. The source architecture docs were ported from /workspace/@alkdev/alknet/docs/architecture/ and renumbered as alkcall ADRs (ADR-001..045). The ALPN strings (alknet/call, alknet/channels) are wire-stable and unchanged — see ADR-004.

Documents

Document Status Description
call-README.md draft Call protocol index — adapter, stream model, registry, client (ported from alknet call/README.md)
call-protocol.md draft CallAdapter, hand-rolled EventEnvelope framing (ADR-014), stream model, PendingRequestMap, bidirectional calls
operation-registry.md draft OperationSpec, Handler, OperationRegistry, AccessControl, service discovery
client-and-adapters.md draft CallClient (transport-agnostic spawn_dispatch), from_call, OperationAdapter trait, no-env-vars invariant
channels-README.md draft Channels protocol index — wire format, adapter, lifecycle, client (ported from alknet channels/README.md)
channels-overview.md draft The multiplexing collapse, crate dependencies, transport agnosticism, WASM
channels-wire.md draft The 8-byte chunk format, sentinels, wire-level invariants (REQ-CH-01..05)
channels-connection.md draft ChannelBidiStreamSource, accept_bi yields one BiStream per channel
channels-adapter.md draft ChannelsAdapter, ChannelManager, demux/mux contracts
channel-operations.md draft channel/open, channel/close, channel/control, channel/resources/subscribe
channel-client.md draft ChannelClient — transport-agnostic from_connection primary

Applicable ADRs

Core (vendored types) — ADR-001..012

ADR Title Relevance
001 ALPN-Based Protocol Dispatch HandlerRegistry, ALPN routing
002 ProtocolHandler Trait The trait every handler implements
003 Auth as Shared Core IdentityProvider, Identity, AuthToken
004 ALPN String Convention alknet/ prefix, one ALPN per connection
005 BiStream Type Definition BiStream, handlers receive Connection
006 AuthContext Structure AuthContext fields, hybrid resolution
007 Connection::from_stream Generic single-stream connections
008 BidiStreamSource Trait Connection extension point
009 BiStream as the Handler Leaf accept_bi returns BiStream (concrete)
010 Secret Material Flow No secrets on wire; Capabilities
011 Dynamic Resource Ownership OwnershipProvider, resource_id_path
012 ConnectionCredentials Transport-level credentials, auth_token is per-request

Call protocol — ADR-013..030

ADR Title Relevance
013 irpc as Call Protocol Foundation Superseded by ADR-014
014 Hand-Rolled EventEnvelope Framing The call wire format ADR; supersedes ADR-013
015 Call Protocol Stream Model Bidi streams, EventEnvelope, ID correlation
016 Operation Error Schemas call.error with typed details
017 Privilege Model internal = authority switch; Visibility
018 Handler Registration Registration bundle, provenance, composition authority
019 Operation Registry Layering Curated + session + connection overlays; OperationEnv trait
020 Abort Cascade call.aborted cascades; abort-dependents default
021 Streaming Handler StreamingHandler, invoke_streaming()
022 Client and Adapter Contract CallClient, from_call, OperationAdapter
023 Peer-Scoped Registry Filtering Superseded by ADR-024
024 Peer-Graph Routing Model PeerCompositeEnv, PeerRef, AccessControl peer auth
025 PeerEntry and Identity.id Decoupling PeerId = Identity.id (stable)
026 Forwarded-For Identity Metadata only, never used by ACL
027 from_jsonschema as HTTP Adapter FromJsonSchema provenance stays; impl in alknet-http
028 from_call Is a Manual Free Function Assembly layer calls it after dial
029 Aggregated Peer-Environment Wiring Dispatcher hub wiring
030 PeerCompositeEnv::peer_operations OperationEnv::peer_operations override

Shared — ADR-031..033

ADR Title Relevance
031 Crate Decomposition alkcall unifies core+call+channels
032 One-Way Door Decision Framework Reversal cost classification
033 Rust as Canonical Implementation Language Rust canonical, TS reference

Channels — ADR-034..045

ADR Title Relevance
034 Channels Wire Format 8-byte chunk header; one-way door
035 Pure Channel Multiplexing No stream_type; BiStream-only; handler owns sub-mux
036 Channel 0 Pre-Negotiated Channel 0 = alknet/call
037 Channel Lifecycle Operations channel/open, close, control, resources/subscribe
038 ChannelConnection Per-channel BidiStreamSource; yield-once accept_bi
039 ChannelsAdapter and ChannelManager Demux/mux; ALPN-blind, auth-blind
040 Backpressure, Limits, ID Reuse Bounded-buffer; 256-channel memory bound
041 Per-Identity Channel Cap ChannelLifecyclePolicy; 256 per PeerId
042 Hub Relay Translate channel 0, byte-forward data channels
043 ChannelClient Transport-agnostic from_connection
044 Channels Sub-Crate Decomposition channels-core / channels-call (modules in alkcall)
045 AlknetClient Dial Seam spawn_dispatch / from_connection take-over; dial in consumer
046 Publish Operation Type and HandlerKind::Sink OperationType::Pub (client→server streaming); SinkHandler + HandlerKind::Sink; call.published wire event; invoke_sink() dispatch; Subscription renamed to Sub
047 Openable ALPNs Are Operations channel/open dissolves into per-ALPN ops channels/<alpn>/sub/pub; channel_open marker on OperationSpec; ChannelCore wrapper; extension-trait ChannelOperationEnv; connection-owner allocates channel_id; opener ledger (Gap 2 fix); ALPNs are call apps

Relevant Open Questions

See open-questions.md for the full tracker. Key questions affecting this crate:

  • OQ-01: Call protocol pub/sub primitive (partially resolved) — ADR-046 adds the Pub primitive (client→server streaming). The fan-out/broker is deferred to channels (Gap B in ADR-047 is named out-of-scope for alkcall; the hub composes the broker on top).
  • OQ-02: Full channel-level flow-control windowing (deferred(scope)) — bounded-buffer is decided (ADR-040); full windowing blocked on a real HOL-blocking deployment observation.
  • OQ-03: Channels add/strip API shape (open) — whether the 8-byte header add/strip is built into the read/write path or a standalone utility.

Key Design Principles

  1. One connection, full access: An alknet/call connection gives access to the entire operation registry.
  2. Protocol is symmetric: Both sides can initiate calls. Producer/ consumer, not server/client.
  3. Hand-rolled framing (no irpc): EventEnvelope is hand-rolled length-prefixed JSON. See ADR-014.
  4. Operation registry is layered: Curated (static) + session + connection overlays. OperationEnv is a trait. See ADR-019.
  5. No secret material on the wire: Capabilities injected at assembly layer. See ADR-010.
  6. Abort cascades to descendants: Default abort-dependents. See ADR-020.
  7. Peer authorization via AccessControl: No remote_safe flag. See ADR-024.
  8. Streams are streams: Every channel is a BiStream. The handler owns its sub-stream multiplexing. See ADR-035.
  9. Channel 0 is alknet/call: Channel lifecycle is call operations on channel 0. See ADR-036, ADR-037.
  10. Wire formats are stable: EventEnvelope shape and the 8-byte chunk header are one-way doors. See ADR-014, ADR-034.

References

  • @alkdev/alknet: docs/architecture/ — the source architecture docs these were ported from (renumbered from alknet ADR-001..094 to alkcall ADR-001..045)
  • @alkdev/alktype — the binary struct engine, used for channels chunk header layout and JSON payload schema validation
  • @alkdev/pubsub — the TypeScript EventEnvelope prior art the call wire format was derived from

Note

: The source ADRs and spec docs were ported from the parent @alkdev/alknet workspace where this crate originated. They are preserved here as the authoritative spec for alkcall; the alknet mono-repo will consume alkcall's versions when it is reworked.

Cross-references to non-ported ADRs: Some spec docs and ADRs reference alknet ADRs by their original numbers (e.g., ADR-052 for TTY's wire format, ADR-082 for alknet-tls, ADR-086 for endpoint types). These are ADRs for sibling crates that are not part of alkcall. They retain their alknet numbering (052, 082, 086, etc.) — any ADR number outside the alkcall range 001..045 is an alknet source ADR, found at /workspace/@alkdev/alknet/docs/architecture/decisions/.