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

## Applicable ADRs

### Core (vendored types) — ADR-001..012

| ADR | Title | Relevance |
|-----|-------|-----------|
| [001](decisions/001-alpn-protocol-dispatch.md) | ALPN-Based Protocol Dispatch | HandlerRegistry, ALPN routing |
| [002](decisions/002-protocol-handler-trait.md) | ProtocolHandler Trait | The trait every handler implements |
| [003](decisions/003-auth-as-shared-core.md) | Auth as Shared Core | IdentityProvider, Identity, AuthToken |
| [004](decisions/004-alpn-convention-and-connection-model.md) | ALPN String Convention | `alknet/` prefix, one ALPN per connection |
| [005](decisions/005-bistream-type-definition.md) | BiStream Type Definition | BiStream, handlers receive Connection |
| [006](decisions/006-authcontext-structure.md) | AuthContext Structure | AuthContext fields, hybrid resolution |
| [007](decisions/007-connection-from-stream-generic-single-stream.md) | Connection::from_stream | Generic single-stream connections |
| [008](decisions/008-bidistreamsource-trait.md) | BidiStreamSource Trait | Connection extension point |
| [009](decisions/009-bistream-as-the-handler-leaf.md) | BiStream as the Handler Leaf | accept_bi returns BiStream (concrete) |
| [010](decisions/010-secret-material-flow-and-capability-injection.md) | Secret Material Flow | No secrets on wire; Capabilities |
| [011](decisions/011-dynamic-resource-ownership-for-runtime-spawned-resources.md) | Dynamic Resource Ownership | OwnershipProvider, resource_id_path |
| [012](decisions/012-connectioncredentials-decouple-dial-from-call.md) | ConnectionCredentials | Transport-level credentials, auth_token is per-request |

### Call protocol — ADR-013..030

| ADR | Title | Relevance |
|-----|-------|-----------|
| [013](decisions/013-irpc-as-call-protocol-foundation.md) | ~~irpc as Call Protocol Foundation~~ | **Superseded** by ADR-014 |
| [014](decisions/014-irpc-never-integrated-hand-rolled-framing.md) | Hand-Rolled EventEnvelope Framing | The call wire format ADR; supersedes ADR-013 |
| [015](decisions/015-call-protocol-stream-model.md) | Call Protocol Stream Model | Bidi streams, EventEnvelope, ID correlation |
| [016](decisions/016-operation-error-schemas.md) | Operation Error Schemas | call.error with typed details |
| [017](decisions/017-privilege-model-and-authority-context.md) | Privilege Model | internal = authority switch; Visibility |
| [018](decisions/018-handler-registration-provenance-and-composition-authority.md) | Handler Registration | Registration bundle, provenance, composition authority |
| [019](decisions/019-operation-registry-layering.md) | Operation Registry Layering | Curated + session + connection overlays; OperationEnv trait |
| [020](decisions/020-abort-cascade-for-nested-calls.md) | Abort Cascade | call.aborted cascades; abort-dependents default |
| [021](decisions/021-streaming-handler-for-subscriptions.md) | Streaming Handler | StreamingHandler, invoke_streaming() |
| [022](decisions/022-call-protocol-client-and-adapter-contract.md) | Client and Adapter Contract | CallClient, from_call, OperationAdapter |
| [023](decisions/023-callclient-peer-scoped-registry-filtering.md) | ~~Peer-Scoped Registry Filtering~~ | **Superseded** by ADR-024 |
| [024](decisions/024-peer-graph-routing-model.md) | Peer-Graph Routing Model | PeerCompositeEnv, PeerRef, AccessControl peer auth |
| [025](decisions/025-peerentry-and-identity-id-decoupling.md) | PeerEntry and Identity.id Decoupling | PeerId = Identity.id (stable) |
| [026](decisions/026-forwarded-for-identity.md) | Forwarded-For Identity | Metadata only, never used by ACL |
| [027](decisions/027-from-jsonschema-as-http-adapter.md) | from_jsonschema as HTTP Adapter | FromJsonSchema provenance stays; impl in alknet-http |
| [028](decisions/028-from-call-manual-free-function.md) | from_call Is a Manual Free Function | Assembly layer calls it after dial |
| [029](decisions/029-aggregated-peer-env-wiring.md) | Aggregated Peer-Environment Wiring | Dispatcher hub wiring |
| [030](decisions/030-peer-composite-env-peer-operations.md) | PeerCompositeEnv::peer_operations | OperationEnv::peer_operations override |

### Shared — ADR-031..033

| ADR | Title | Relevance |
|-----|-------|-----------|
| [031](decisions/031-crate-decomposition.md) | Crate Decomposition | alkcall unifies core+call+channels |
| [032](decisions/032-one-way-door-decision-framework.md) | One-Way Door Decision Framework | Reversal cost classification |
| [033](decisions/033-rust-canonical-implementation.md) | Rust as Canonical Implementation Language | Rust canonical, TS reference |

### Channels — ADR-034..045

| ADR | Title | Relevance |
|-----|-------|-----------|
| [034](decisions/034-channels-wire-format.md) | Channels Wire Format | 8-byte chunk header; one-way door |
| [035](decisions/035-channels-pure-channel-multiplexing.md) | Pure Channel Multiplexing | No stream_type; BiStream-only; handler owns sub-mux |
| [036](decisions/036-channel-0-pre-negotiated-call.md) | Channel 0 Pre-Negotiated | Channel 0 = alknet/call |
| [037](decisions/037-channel-lifecycle-operations.md) | Channel Lifecycle Operations | channel/open, close, control, resources/subscribe |
| [038](decisions/038-channelconnection-bidistreamsource.md) | ChannelConnection | Per-channel BidiStreamSource; yield-once accept_bi |
| [039](decisions/039-channelsadapter-and-channelmanager.md) | ChannelsAdapter and ChannelManager | Demux/mux; ALPN-blind, auth-blind |
| [040](decisions/040-backpressure-channel-limits-id-reuse.md) | Backpressure, Limits, ID Reuse | Bounded-buffer; 256-channel memory bound |
| [041](decisions/041-per-identity-channel-cap.md) | Per-Identity Channel Cap | ChannelLifecyclePolicy; 256 per PeerId |
| [042](decisions/042-hub-relay-translate-not-forward.md) | Hub Relay | Translate channel 0, byte-forward data channels |
| [043](decisions/043-channelclient.md) | ChannelClient | Transport-agnostic from_connection |
| [044](decisions/044-channels-subcrate-decomposition.md) | Channels Sub-Crate Decomposition | channels-core / channels-call (modules in alkcall) |
| [045](decisions/045-alknetclient-native-dial-seam.md) | AlknetClient Dial Seam | spawn_dispatch / from_connection take-over; dial in consumer |
| [046](decisions/046-publish-operation-type-and-handler-kind-sink.md) | 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` |

## Relevant Open Questions

See [open-questions.md](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.
- **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/`.