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docs(arch): call-completion — ADR-028 peer-scoped filtering + client-and-adapters spec + tasks

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Resolves the four gap-analysis decisions (DC-1..4) blocking the alknet-call
client/adapter surface specced in ADR-017:

- ADR-028 (new): locks the one-way door for DC-1 — CallClient registry is
  default-deny (remote_safe: bool on HandlerRegistration, default false across
  all provenance); share-global is an explicit trusted-peer opt-in; filtering
  is a dispatch-time read over the single Layer-0 registry, not a copy.
- client-and-adapters.md (new spec): operationally fills the gap ADR-017 left
  to implementation — CallClient, from_call, from_jsonschema, OperationAdapter
  trait, adapter location map, no-env-vars invariant, exchange-of-operations
  pattern. Keeps call-protocol.md and operation-registry.md under the
  700-line split threshold.
- ADR-017 amended: records DC-2/3/4 v1 defaults (auto-on-reconnect,
  error-on-collision, Result error type) and points DC-1 at ADR-028.
- OQ-25..28 (new): two-way-door remainders (remote_safe shape, AdapterError
  variants, re-import trigger, namespace collision) with v1 defaults recorded.
- Index/cross-ref updates across READMEs and the two existing call specs.

Tasks: 6 task files under tasks/call/ decomposing the completion work along
the gap-analysis priority order — remote-safe-marking (one-way door, first)
→ call-client (phase-risk) → from-call → operation-adapter-trait →
from-jsonschema (parallel with call-client) → review-completion. Graph
validated with taskgraph; parallelism designed in (from-jsonschema runs
concurrent with call-client/from-call once the trait lands).
This commit is contained in:
glm-5.2
2026-06-26 12:25:13 +00:00
parent 6940d9858d
commit 2649e068e5
14 changed files with 1817 additions and 11 deletions
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@@ -1,15 +1,17 @@
---
status: draft
last_updated: 2026-06-23
last_updated: 2026-06-26
---
# Alknet Architecture
## Current State
**Pre-implementation.** The project has completed a pivot from a three-layer model to an ALPN-as-service model. The greenfield workspace contains only `alknet-vault` (stable — implementation complete and verified, local-only by construction per ADR-025, HD-derivation key model per ADR-026) and research/reference material. Foundational ADRs (001–026) are in place. ADR-024 resolves the registry mutability question and the `OperationContext.env` type identity crisis by layering the registry by trust boundary. ADR-025 drops irpc from the vault, making it local-only by construction. ADR-026 records the HD-derivation key model as a foundational decision. Review #003 (type/API surface completeness) resolved: `DerivedKey` derive contradiction, `encrypt` prose, return-type divergence, RwLock contradiction, drift table gaps, ADR-022 stale sketches, `Capabilities`/`SessionOverlaySource`/`CallConnection`/`CachedKey` definitions, `CompositeOperationEnv` dispatch contract, `with_local` signature, payload schemas, timeout propagation, and request ID generation. The alknet-core and alknet-call crate specs are in draft; the alknet-vault crate specs are stable.
**Pre-implementation.** The project has completed a pivot from a three-layer model to an ALPN-as-service model. The greenfield workspace contains only `alknet-vault` (stable — implementation complete and verified, local-only by construction per ADR-025, HD-derivation key model per ADR-026) and research/reference material. Foundational ADRs (001–028) are in place. ADR-024 resolves the registry mutability question and the `OperationContext.env` type identity crisis by layering the registry by trust boundary. ADR-025 drops irpc from the vault, making it local-only by construction. ADR-026 records the HD-derivation key model as a foundational decision. Review #003 (type/API surface completeness) resolved: `DerivedKey` derive contradiction, `encrypt` prose, return-type divergence, RwLock contradiction, drift table gaps, ADR-022 stale sketches, `Capabilities`/`SessionOverlaySource`/`CallConnection`/`CachedKey` definitions, `CompositeOperationEnv` dispatch contract, `with_local` signature, payload schemas, timeout propagation, and request ID generation. The alknet-core and alknet-call crate specs are in draft; the alknet-vault crate specs are stable.
**Next step**: Implementation. All open questions are resolved. The specs have passed three review passes (#001 governance/security model, #002 cross-document consistency/two-way-door audit, #003 type/API surface completeness).
The alknet-call server-side core (`CallAdapter`, `CallConnection` dispatch loop, wire framing, pending map, abort cascade, operation registry, service discovery) is implemented and tested (159 tests passing). The call-completion gap analysis (`docs/research/alknet-call-completion/gap-analysis.md`) identified the missing client/adapter surface specced in ADR-017 — `CallClient`, `from_call`, `from_jsonschema`, the `OperationAdapter` trait — plus four decisions (DC-1..4) needed before implementation. DC-1 (the one-way door: peer-scoped registry filtering) is resolved by ADR-028; DC-2/3/4 are two-way-door defaults recorded in `client-and-adapters.md` and tracked as OQ-25..28. The client/adapter surface is specced (`crates/call/client-and-adapters.md`); implementation is pending.
**Next step**: Implementation of the alknet-call client/adapter surface (priority order in `client-and-adapters.md`): `CallClient` → `from_call` → `OperationAdapter` trait → `from_jsonschema`. All one-way doors are resolved; remaining open questions (OQ-25..28) are two-way-door shape/defaults decided during implementation.
## Architecture Documents
@@ -25,6 +27,7 @@ last_updated: 2026-06-23
| [crates/call/README.md](crates/call/README.md) | draft | alknet-call crate index |
| [crates/call/call-protocol.md](crates/call/call-protocol.md) | draft | CallAdapter, EventEnvelope framing, stream model, PendingRequestMap, bidirectional calls, streaming subscribe example |
| [crates/call/operation-registry.md](crates/call/operation-registry.md) | draft | OperationSpec, Handler, OperationRegistry, AccessControl, capability injection, service discovery, irpc integration |
| [crates/call/client-and-adapters.md](crates/call/client-and-adapters.md) | draft | CallClient (outbound connection opener), from_call / from_jsonschema, OperationAdapter trait, adapter location map, no-env-vars invariant, exchange-of-operations pattern |
| [crates/vault/README.md](crates/vault/README.md) | stable | alknet-vault crate index |
| [crates/vault/mnemonic-derivation.md](crates/vault/mnemonic-derivation.md) | stable | BIP39, SLIP-0010, BIP-0032, derivation paths, key types |
| [crates/vault/encryption.md](crates/vault/encryption.md) | stable | AES-256-GCM, EncryptedData, key versioning, salt (Phase B reserved) |
@@ -62,6 +65,7 @@ last_updated: 2026-06-23
| [025](decisions/025-vault-local-only-dispatch.md) | Vault Local-Only Dispatch | Accepted |
| [026](decisions/026-vault-key-model-hd-derivation.md) | Vault Key Model — HD Derivation | Accepted |
| [027](decisions/027-tls-identity-redesign-acme-rawkey-decoupling.md) | TLS Identity Redesign — ACME + RawKey Decoupling | Accepted |
| [028](decisions/028-callclient-peer-scoped-registry-filtering.md) | Peer-Scoped Registry Filtering for CallClient Inbound Dispatch | Accepted |
## Open Questions
@@ -93,6 +97,12 @@ See [open-questions.md](open-questions.md) for the full tracker.
- **OQ-23**: Handler identity registration path — registration bundle with provenance, composition authority, scoped env, capabilities (ADR-022)
- **OQ-24**: Operation error schemas — declared domain errors with typed `details` payload; adapter fidelity for `from_openapi`/`to_openapi` (ADR-023)
**Open (two-way-door remainders from alknet-call completion):**
- **OQ-25**: Remote-safe marking shape — existence of default-deny `CallClient` filtering locked by ADR-028; shape (`remote_safe: bool` v1 vs per-peer allowlist) open
- **OQ-26**: `OperationAdapter` error type — `import()` returns `Result<_, AdapterError>`; variants decided in implementation
- **OQ-27**: `from_call` re-import trigger — v1 default auto-on-reconnect; explicit `refresh()` additive
- **OQ-28**: `from_call` namespace collision — v1 default error-on-collision (no prefix by default)
**Deferred (not active):**
- **OQ-09**: WASM target boundaries — design constraint, not deliverable
- **OQ-10**: Git adapter scope — start with smart protocol, add ERC721 later

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@@ -1,7 +1,7 @@
---
status: draft
last_updated: 2026-06-23
review: call/review-call passed 2026-06-23 — registry, protocol, ADR (005/012/014/015/016/017/022/023/024), security, and pattern-consistency checks all conformant; 159 unit/integration tests green; `cargo build`, `cargo clippy -- -D warnings`, `cargo fmt --check`, `cargo test` clean.
last_updated: 2026-06-26
review: call/review-call passed 2026-06-23 — registry, protocol, ADR (005/012/014/015/016/017/022/023/024), security, and pattern-consistency checks all conformant; 159 unit/integration tests green; `cargo build`, `cargo clippy -- -D warnings`, `cargo fmt --check`, `cargo test` clean. Call-completion gap (ADR-017 client/adapter surface) addressed 2026-06-26 — ADR-028 + client-and-adapters.md added; implementation pending.
---
# alknet-call
@@ -14,6 +14,7 @@ Structured RPC over QUIC: operations, request/response, streaming subscriptions,
|----------|--------|-------------|
| [call-protocol.md](call-protocol.md) | draft | CallAdapter, EventEnvelope framing, stream model, PendingRequestMap, bidirectional calls |
| [operation-registry.md](operation-registry.md) | draft | OperationSpec, Handler, OperationRegistry, AccessControl, service discovery, irpc integration |
| [client-and-adapters.md](client-and-adapters.md) | draft | CallClient (outbound connection opener), from_call / from_jsonschema, OperationAdapter trait, adapter location map, no-env-vars invariant, exchange-of-operations pattern |
## Applicable ADRs
@@ -37,6 +38,7 @@ Structured RPC over QUIC: operations, request/response, streaming subscriptions,
| [022](../../decisions/022-handler-registration-provenance-and-composition-authority.md) | Handler Registration, Provenance, and Composition Authority | Registration bundle carries provenance, composition authority, scoped env, capabilities |
| [023](../../decisions/023-operation-error-schemas.md) | Operation Error Schemas | Operations declare domain errors; `call.error` carries typed `details`; adapter fidelity |
| [024](../../decisions/024-operation-registry-layering.md) | Operation Registry Layering | Curated (static) + session/connection overlays (dynamic); `OperationEnv` as trait-object integration point; `OperationContext.env` split into `scoped_env` (data) and `env` (dispatch trait) |
| [028](../../decisions/028-callclient-peer-scoped-registry-filtering.md) | Peer-Scoped Registry Filtering for CallClient Inbound Dispatch | Default-deny peer-scoped registry view; `remote_safe` marking on `HandlerRegistration`; trusted-peer opt-in; locks the ADR-017 §1 security-dimension one-way door |
## Relevant Open Questions
@@ -47,6 +49,10 @@ Structured RPC over QUIC: operations, request/response, streaming subscriptions,
| OQ-14 | Batch operation semantics | resolved | Correlated `call.requested` events is the correct protocol design |
| OQ-16 | Safe vault operations for call protocol exposure | resolved (ADR-014) | None exposed for now |
| OQ-19 | Session-scoped operation registries | resolved | Agent-written operations overlaid on curated registry via `OperationEnv` trait layering. Protocol doesn't need changes; `OperationEnv` must remain a trait. Generalized by ADR-024 to cover connection-scoped overlays. |
| OQ-25 | Remote-safe marking shape for CallClient peer-scoped filtering | open (two-way) | Existence of default-deny filtering locked by ADR-028; shape (`remote_safe: bool` v1 vs per-peer allowlist) is the two-way-door remainder |
| OQ-26 | OperationAdapter error type (AdapterError variants) | open (two-way) | `import()` returns `Result<_, AdapterError>`; variants decided in implementation |
| OQ-27 | from_call re-import trigger | open (two-way) | v1 default: auto-on-reconnect; explicit `refresh()` is additive |
| OQ-28 | from_call namespace collision behavior | open (two-way) | v1 default: error on collision (no prefix by default) |
## Key Design Principles
@@ -60,3 +66,7 @@ Structured RPC over QUIC: operations, request/response, streaming subscriptions,
8. **Abort cascades to descendants**: `call.aborted` for a parent request cascades to all non-terminal descendants. Default `abort-dependents`; `continue-running` opt-in. See ADR-016.
9. **Internal calls switch authority context, not skip ACL**: The `internal` flag marks composition-originated calls. ACL runs against the handler's composition authority, not the caller's and not as a blanket skip. Operations have External/Internal visibility. Scoped composition env bounds reachability. See ADR-015, ADR-022.
10. **Provenance determines composition capability**: Only `Local` and `Session` ops can compose. Leaves (`FromOpenAPI`, `FromMCP`, `FromCall`) are forwarding stubs — they don't get composition authority or a scoped env. The assembly layer is the sole grantor of composition authority. See ADR-022.
11. **Connection direction is independent of call direction**: Who opens the QUIC connection is a connection-layer concern, not a protocol-layer concern. Both sides can call each other once connected. The `CallAdapter` accepts connections; the `CallClient` opens them; both produce the same `CallConnection` and dispatch through the same loop. See ADR-017, [client-and-adapters.md](client-and-adapters.md).
12. **CallClient registry is default-deny**: A `CallClient` exposes no operations to the remote peer unless explicitly marked remote-safe. Sharing the global registry is an explicit trusted-peer opt-in, never the default. This prevents a remote peer's call from triggering dispatch that populates `OperationContext.capabilities` from the local node's registration bundle. See ADR-028.
13. **Adapter trait lives with the types; implementations live with their transport**: `OperationAdapter` is in `alknet-call`; `from_call`/`from_jsonschema` are in `alknet-call` (QUIC / pure parse); `from_openapi`/`from_mcp`/`to_openapi`/`to_mcp` are in `alknet-http` (reqwest / axum). `alknet-call` stays lean — no HTTP client, no HTTP server. See [client-and-adapters.md](client-and-adapters.md).
14. **No handler reads outbound credentials from any source other than `OperationContext.capabilities`** (no-env-vars invariant): the credential injection path is vault → assembly layer → `Capabilities` → `HandlerRegistration.capabilities` → `OperationContext.capabilities` → handler. Downstream consumers' `std::env::var` reads are unreachable because the assembly layer never calls `Default::default()`. See ADR-014, [client-and-adapters.md](client-and-adapters.md).

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@@ -524,8 +524,9 @@ Handlers clean up resources when their call is cancelled (in Rust, the future is
| Secret material flow | [ADR-014](../../decisions/014-secret-material-flow-and-capability-injection.md) | Call protocol carries no secret material; capabilities injected at assembly layer |
| Privilege model and authority context | [ADR-015](../../decisions/015-privilege-model-and-authority-context.md) | `internal` = authority switch not ACL skip; External/Internal visibility; handler identity + scoped env |
| Abort cascade for nested calls | [ADR-016](../../decisions/016-abort-cascade-for-nested-calls.md) | `call.aborted` cascades to descendants; default `abort-dependents`, `continue-running` opt-in |
| Call protocol client and adapter contract | [ADR-017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | `CallClient` opens connections; `from_call` imports remote ops; connection direction independent of call direction |
| Call protocol client and adapter contract | [ADR-017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | `CallClient` opens connections; `from_call` imports remote ops; connection direction independent of call direction. Client/adapter surface specced in [client-and-adapters.md](client-and-adapters.md) |
| Handler registration, provenance, and composition authority | [ADR-022](../../decisions/022-handler-registration-provenance-and-composition-authority.md) | Registration bundle carries provenance, composition authority, scoped env, capabilities; dispatch path reads from bundle |
| Peer-scoped registry filtering for CallClient | [ADR-028](../../decisions/028-callclient-peer-scoped-registry-filtering.md) | Default-deny `CallClient` registry view; `remote_safe` marking; trusted-peer opt-in |
| Operation error schemas | [ADR-023](../../decisions/023-operation-error-schemas.md) | Operations declare domain errors; `call.error` carries typed `details` |
## Open Questions
@@ -536,6 +537,7 @@ See [open-questions.md](../../open-questions.md) for full details.
- **OQ-14** (resolved): Batch is a client-side pattern of correlated `call.requested` events, not a protocol primitive.
- **OQ-16** (resolved by ADR-014): No vault operations are exposed over the call protocol for now.
- **OQ-19** (resolved): Session-scoped operation registries — agent-written operations overlaid on global registry via `OperationEnv` trait layering. Protocol doesn't need changes; `OperationEnv` must remain a trait.
- **OQ-25..28** (open, two-way): Call-completion remainders — `CallClient` remote-safe marking shape, `OperationAdapter` error type, `from_call` re-import trigger, `from_call` namespace collision. The `CallClient`/adapter surface itself is specced in [client-and-adapters.md](client-and-adapters.md); the one-way door among these (existence of default-deny filtering) is resolved by ADR-028.
## References

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@@ -0,0 +1,537 @@
---
status: draft
last_updated: 2026-06-26
---
# alknet-call — Client and Adapters
The outbound half of the call protocol: opening connections, importing remote
operations, and the adapter contract that ties import-style adapters together.
This document covers what ADR-017 specced but the server-side implementation
(`call-protocol.md`, `operation-registry.md`) did not include — the `CallClient`
that *opens* a connection, the `from_call`/`from_jsonschema` adapters, and the
`OperationAdapter` trait. The server-side `CallAdapter` and `CallConnection`
dispatch loop are covered in `call-protocol.md`; this document covers the
client-side connection-establishment half and the adapter surface.
## What
This document specifies four components, all in `alknet-call`:
1. **`CallClient`** — opens an outbound `alknet/call` QUIC connection and
produces a `CallConnection`. The dispatch loop is shared with the
server-side `CallAdapter` (ADR-017 §1); `CallClient` is the
connection-establishment + credential-handling half, not a parallel
protocol implementation.
2. **`from_call`** — discovers operations on a remote call-protocol endpoint
via `services/list` + `services/schema` (already implemented in
`registry/discovery.rs`) and registers them in the connection's Layer 2
overlay as `FromCall`-provenance leaves with forwarding handlers.
3. **`from_jsonschema`** — schema-only registration: produces
`HandlerRegistration` bundles with no handler, for validation, discovery,
and composition-graph construction without a runtime.
4. **`OperationAdapter` trait** — the async trait that `from_call`,
`from_openapi`, `from_mcp`, and `from_jsonschema` all implement.
It also records two cross-cutting architectural mechanisms that the adapter
surface rests on:
- The **adapter location map** — which adapters live in `alknet-call` vs
`alknet-http`, and why.
- The **no-env-vars invariant** — the architectural mechanism by which
downstream consumers' `std::env::var` credential reads are made unreachable.
And one downstream pattern this completion unblocks:
- The **exchange-of-operations pattern** (runner / container service) — the
canonical bilateral composition this client surface enables.
## Why
The server-side `CallAdapter` (accept path) and `CallConnection` (dispatch
loop) are implemented and tested. The client side is the #1 gap blocking every
downstream consumer: the runner pattern (a process that connects outward to a
hub and exposes local ops), the container-service rewrite, the bilateral
exchange, the NAPI projection, and the agent's cross-node tool dispatch all
require a `CallClient`. `from_call` is the #2 gap; the `OperationAdapter`
trait is the enabling gap for `alknet-http`'s `from_openapi`/`from_mcp`.
ADR-017 specced this surface. This document is the spec that operationally
fills the gap ADR-017 left to implementation: the `CallClient` API, the
`from_call`/`from_jsonschema` flows, the trait signature, the adapter
location, the credential invariant, and the bilateral pattern. The gap
analysis (`docs/research/alknet-call-completion/gap-analysis.md`) identified
four decisions (DC-1..4) needed before implementation; DC-1 is resolved by
ADR-028, and DC-2/3/4 are two-way-door defaults recorded here and tracked as
OQs (DC-2→OQ-27, DC-3→OQ-28, DC-4→OQ-26).
## Architecture
### CallClient
`CallClient` opens a QUIC connection to a remote node on ALPN `alknet/call`,
performs credential setup, and produces a `CallConnection`. The
`CallConnection` type is already implemented (`call-protocol.md` §"CallConnection")
— it wraps an established `Connection` and holds the Layer 2 imported-ops
overlay. `CallClient` is the producer on the outbound side; `CallAdapter`'s
accept path is the producer on the inbound side. Both produce the same
`CallConnection` and hand it to the same shared dispatch loop.
```rust
pub struct CallClient {
/// The operation registry. The peer-scoped view is a dispatch-time read
/// over this registry, not a copy (ADR-028 §5).
registry: Arc<OperationRegistry>,
identity_provider: Arc<dyn IdentityProvider>,
/// Trusted-peer mode (ADR-028 §3): when true, the dispatch path exposes
/// all External ops to the remote peer and `services/list` lists all
/// External ops, ignoring the `remote_safe` marking. When false
/// (default), only registrations with `remote_safe: true` dispatch, and
/// `services/list` hides non-remote-safe ops (ADR-028 Assumption 2).
trusted_peer: bool,
}
impl CallClient {
/// Open a QUIC connection to `addr` on ALPN `alknet/call`, perform
/// credential handshake, and return a CallConnection running the shared
/// dispatch loop. Credentials come from capabilities (ADR-014), not env
/// vars — see "No-Env-Vars Invariant" below.
pub async fn connect(
&self,
addr: SocketAddr,
credentials: CallCredentials,
) -> Result<CallConnection>;
/// Trusted-peer mode: construct a CallClient that exposes all External
/// ops from `registry` to the remote peer, ignoring the remote-safe
/// marking. Explicit opt-in per ADR-028 §3.
pub fn trusted_peer(
registry: Arc<OperationRegistry>,
identity_provider: Arc<dyn IdentityProvider>,
) -> Self;
}
```
The v1 mechanism is the `trusted_peer: bool` flag plus the `remote_safe: bool`
field on each `HandlerRegistration` (default `false` across all provenance,
ADR-028 §4). A richer per-peer filtering mechanism (per-peer allowlist,
capability-class tag) is the two-way-door remainder tracked as OQ-25; v1's
boolean limits exposure control to "remote-safe for any peer" vs "not," which
is acceptable for the runner/dispatch pattern (one remote peer per
`CallClient`).
The connection is symmetric after establishment (ADR-017 §2): both sides can
send and receive `call.requested`. Connection direction (who opened it) is
independent of call direction (who calls whom). The `CallClient` is therefore
both a caller and a callee — it dispatches incoming calls from the remote
peer against its peer-scoped registry view, and it initiates outgoing calls
through the `CallConnection::call()` / `subscribe()` / `abort()` API.
### Credential sources for connections
`CallClient::connect()` takes a `CallCredentials` bundle. Credentials come
from `Capabilities` (ADR-014), never from environment variables. The three
credential dimensions (ADR-017 §7):
```rust
pub struct CallCredentials {
pub tls_identity: Option<TlsIdentity>, // RFC 7250 raw key or X.509
pub auth_token: Option<AuthToken>, // call-protocol-level token
pub remote_identity: Option<RemoteIdentity>, // expected fingerprint/cert
}
```
- **TLS identity** — the local node's Ed25519 raw key (RFC 7250) or X.509 cert,
derived from the vault at startup (ADR-020, ADR-026, ADR-027).
- **Auth token** — an opaque call-protocol-level token, decrypted from the
vault or derived from a shared secret.
- **Remote identity verification** — the expected fingerprint/cert of the
remote node, stored as a capability.
These are populated by the assembly layer at `CallClient` construction time
from vault-derived `Capabilities`. The credential path is the no-env-vars
invariant (below). The concrete shapes of `TlsIdentity`, `AuthToken`, and
`RemoteIdentity` are implementation-detail two-way doors; the one-way
constraints are that they come from `Capabilities`, not env vars (ADR-014).
### from_call
`from_call` discovers the remote peer's `External` operations and registers
them in the connection's Layer 2 overlay as `FromCall`-provenance leaves with
forwarding handlers. The discovery mechanism (`services/list` +
`services/schema`) is already implemented in `registry/discovery.rs`;
`from_call` is the client-side consumer of that API.
```rust
pub struct FromCallConfig {
/// Namespace prefix applied to imported operation names. Optional —
/// default no prefix. Collision on import is an error (DC-3, OQ-28),
/// not last-wins.
pub namespace_prefix: Option<String>,
/// Optional filter — import only operations whose names match. None
/// imports all External ops discovered via services/list.
pub operation_filter: Option<HashSet<String>>,
}
/// Discover the remote peer's External ops and construct HandlerRegistration
/// bundles with FromCall provenance and forwarding handlers. The caller
/// registers the bundles in the connection's overlay via
/// CallConnection::register_imported_all().
pub async fn from_call(
connection: &CallConnection,
config: FromCallConfig,
) -> Result<Vec<HandlerRegistration>, AdapterError>;
```
The flow (ADR-017 §3):
1. Call `services/list` on the remote → list of `External` operations.
2. Call `services/schema` for each → input/output JSON Schemas and declared
`error_schemas` (ADR-023).
3. For each discovered op, construct a `HandlerRegistration`:
- `spec` mirrors the remote op's name (with optional prefix), namespace,
type, schemas, access control.
- `handler` is a forwarding handler: sends `call.requested` through the
`CallConnection`, awaits `call.responded` (or streams for subscriptions).
- `provenance: FromCall`, `composition_authority: None`, `scoped_env: None`
(leaf — ADR-022).
4. The caller registers the bundles via
`CallConnection::register_imported_all()`.
**Re-import on reconnection** (DC-2, OQ-27): `from_call` runs automatically on
connection establishment. The overlay is per-connection (Layer 2, ADR-024), so
a stale overlay dies with the connection; re-import on reconnect is naturally
scoped to the new connection. This is the v1 default; explicit re-import via a
future `CallConnection::refresh()` is additive.
**Namespace collision** (DC-3, OQ-28): optional prefix, default no prefix,
collision = error. A node importing from two remotes that both expose
`/container/exec` without prefixes should fail loudly. The operator adds
prefixes when they know they're importing from multiple sources.
**Trust is transitive** (recorded in `operation-registry.md`): a
`from_call`-imported operation executes the remote node's code, not yours.
The scoped env (ADR-015) bounds *which* operations are reachable, not *what*
they do. `from_call` means "I trust the remote node as much as my own
handlers." The abort cascade (ADR-016) crosses the node boundary transparently
through the forwarding handler's `parent_request_id`.
### from_jsonschema
Schema-only registration: produces `HandlerRegistration` bundles with no
handler (`FromJsonSchema` provenance). Used for validation, discovery, and
composition-graph construction without a runtime — type-checking a composition
plan without executing it, building a UI of available operations without
standing up the transports, etc.
```rust
pub fn from_jsonschema(
spec: OperationSpec,
schema: serde_json::Value,
) -> HandlerRegistration;
```
Distinct from `from_call` (gap analysis DC-5, confirmed not a decision):
| | `from_jsonschema` | `from_call` |
|---|---|---|
| Schema source | Provided directly (caller fetches, passes in) | Discovered over wire (`services/list` + `services/schema`) |
| Handler at call time | None (schema-only, `FromJsonSchema` provenance) | Forwards over QUIC (`FromCall` provenance, leaf) |
| Use case | Type validation, discovery, composition graph construction | Actually invoking remote operations |
Keeping them separate preserves the "schema-only, no execution" use case
(type checking, safe composition planning without runtime).
### OperationAdapter trait
The shared shape across import-style adapters. The trait lives in
`alknet-call` (where the types live); the implementations live where their
transport dependencies live (see "Adapter Location Map" below).
```rust
#[async_trait]
pub trait OperationAdapter: Send + Sync {
async fn import(&self) -> Result<Vec<HandlerRegistration>, AdapterError>;
}
```
The trait is **async** because `from_call` requires async discovery
(`services/list` + `services/schema` over a QUIC connection). Sync adapters
(`from_openapi`, `from_mcp` reading a static spec) trivially satisfy an async
trait — their `import()` bodies contain no `.await` points. This is locked by
ADR-017 §5.
The **error type** (DC-4, OQ-26) is `Result<Vec<HandlerRegistration>,
AdapterError>` where `AdapterError` is a crate-level enum covering the
failure modes real implementations hit: discovery transport failure
(`from_call` remote unreachable), schema parse failure (`from_openapi`,
`from_jsonschema`), unauthorized (HTTP 401 for `from_openapi`,
`from_mcp`). The exact `AdapterError` variants are the two-way-door
remainder; the *presence* of an error type is filled in here. ADR-017 §5
showed `async fn import(&self) -> Vec<HandlerRegistration>` with no error
type; the spec omitted the error type as an implementation-detail two-way
door, recorded here.
Implementations:
- `FromCall` — QUIC-backed (in `alknet-call`).
- `FromJsonSchema` — pure parse, no transport (in `alknet-call`).
- `FromOpenAPI` — HTTP-backed (in `alknet-http`).
- `FromMCP` — MCP streamable-HTTP-backed (in `alknet-http`, feature-gated).
The `to_*` adapters (`to_openapi`, `to_mcp`) are outbound projections, not
`OperationAdapter` implementations — they consume the registry, they don't
produce entries for it (ADR-017 §5).
### Adapter Location Map
The decomposition principle: **the adapter trait lives where the types live
(`alknet-call`); the adapter implementations live where their transport
dependencies live.**
```
alknet-call (lean — no HTTP client, no HTTP server)
├── OperationAdapter trait (the contract — async, per ADR-017 §5)
├── from_call (QUIC — discovers remote ops via call protocol)
├── from_jsonschema (pure parse — caller fetches the doc, passes it in)
└── CallClient (outbound connection opener — the #1 gap)
alknet-http (owns HTTP server + HTTP client — separate crate, separate Phase 0)
├── ProtocolHandler for h2/http1.1/h3 (axum server — inbound HTTP)
├── from_openapi (parse OpenAPI doc + reqwest forwarding handler)
├── to_openapi (generate OpenAPI doc from local registry)
├── from_mcp (feature-gated) (import remote MCP tools over streamable HTTP — reqwest)
└── to_mcp (feature-gated) (expose local ops as MCP tools over streamable HTTP — axum)
Not built: MCP stdio transport
— stdio = spawn arbitrary executable = built-in RCE ("download untrusted MCP servers")
— streamable HTTP is the only supported MCP transport in alknet
— recorded as an explicit security position, not a feature gap
```
`alknet-call` never sees the HTTP client. The `from_openapi`/`from_mcp`
forwarding handlers are opaque `Arc<dyn Handler>` from the registry's
perspective — constructed by `alknet_http::from_openapi()` at registration
time, stored in `HandlerRegistration`, dispatched by the `CallAdapter` which
doesn't know reqwest is involved. `alknet-call` stays lean (no reqwest, no
axum); `alknet-http` owns both HTTP directions.
**ADR-003 dependency note**: `alknet-http` implementing `from_openapi`/
`from_mcp` means `alknet-http` depends on `alknet-call` (for `OperationSpec`,
`Handler`, `HandlerRegistration`, `OperationAdapter`). ADR-003's rule is "no
handler crate depends on another handler crate" — but `alknet-call` is both
a handler *and* the protocol foundation that `alknet-agent` and `alknet-napi`
already consume. `alknet-http` depending on `alknet-call` is "HTTP uses the
call protocol types," not "HTTP depends on SSH." This is within the spirit of
ADR-003 (`alknet-call` is protocol-foundation, not a peer handler). The
`alknet-http` spec should note this explicitly; a one-line amendment to
ADR-003 clarifying that `alknet-call` is a protocol-foundation crate is
deferred to the `alknet-http` Phase 0.
### No-Env-Vars Invariant
The architectural mechanism for the env-var problem in downstream consumers
(the Rust port of Vercel's AI SDK at `/workspace/aisdk/`, whose providers all
read `std::env::var("OPENAI_API_KEY")` in their `Default` impls). The fix is
**not** to modify those consumers — it's that the env-var path is never taken
because the assembly layer never calls `Default::default()`.
The credential injection path:
```
vault (seed)
→ assembly layer (derive + decrypt at startup, per ADR-014/019/025)
→ Capabilities (non-serializable, zeroized, immutable — ADR-014)
→ HandlerRegistration.capabilities (ADR-022, the registration bundle)
→ OperationContext.capabilities (per-request, populated by dispatch
path from the bundle — ADR-022 §6)
→ from_openapi handler reads context.capabilities.get("openai")
→ injects into HTTP Authorization header
→ reqwest request goes out with vault-derived credential
```
The `from_openapi`/`from_mcp` forwarding handlers (in `alknet-http`) are the
credential injection point. They read from `context.capabilities`, not from
`std::env::var`. The downstream consumers' `Default` impls reading env vars
are simply never called — the assembly layer constructs providers with
vault-derived credentials through the builder API, or the provider's HTTP
calls are routed through `from_openapi` operations that carry the credential
in `Capabilities`.
**This is a spec-level invariant in `alknet-call`, not a runtime convention.**
The dispatch path (`build_root_context` and `OperationEnv::invoke()` per
ADR-022 §6) populates `OperationContext.capabilities` from the registration
bundle. The invariant is: *no handler reads outbound credentials from any
source other than `OperationContext.capabilities`.* This is already the
architectural intent of ADR-014; this document records it as an explicit
invariant that the `from_openapi`/`from_mcp` handler implementations (in
`alknet-http`) are verified against.
### Exchange-of-Operations Pattern (Runner / Container Service)
The canonical downstream pattern this completion unblocks, recorded here so
Phase 1 specs can reference it. Concrete example: the container service at
`/workspace/@alkdev/dispatch` (axum + russh SSH client for "reverse git
runner" over Docker/vast.ai) gets rewritten as a call-protocol service.
**Bilateral exchange**:
```
Container service (runs on a vast.ai/docker instance):
Defines Local ops: /container/exec, /container/list, /container/logs...
(real handlers — calls bollard or vast.ai API)
Connects to hub as a CallClient (outbound connection — runner pattern)
Hub (central server):
Runs CallAdapter (server) on alknet/call (already implemented)
When the container service connects:
hub runs from_call → discovers /container/* via services/list + services/schema
registers them as FromCall provenance (leaf, forwarding handlers) in the
connection's Layer 2 overlay (ADR-024)
Now the hub (or anything connected to the hub) can call /container/exec
The from_call handler forwards over the connection back to the container service
Bilateral: the container service ALSO runs from_call against the hub,
discovers the hub's External ops, and can call them.
Connection direction (container → hub) is independent of call direction
(both can call each other) per ADR-017 §2.
```
**What this requires**:
1. `CallClient` — the container service uses it to open the outbound
connection to the hub. The #1 gap.
2. `from_call` — both sides run it to populate their Layer 2 overlays with
the other side's `External` ops. The #2 gap.
3. `OperationAdapter` trait — `from_call` implements it. The #3 gap (enabling,
not blocking — `from_call` can be built as a free function before the trait
exists, but the trait is needed for `alknet-http`'s adapters).
**Why the container service doesn't need alknet-ssh**: under the call
protocol, the container service is a `CallClient` that dials the hub's
`alknet/call` ALPN directly over QUIC — no SSH in the loop. SSH port
forwarding becomes the *transitional* mechanism for targets that can't run a
call-protocol client (the `alknet-ssh` phase-0 findings document this
transition). Once the container service runs a `CallClient`, SSH is out of
the path entirely.
This is the "dev runner" pattern: a call-protocol client that connects back
to a hub and exposes core dev tools (bash, fs, etc.) as operations. The agent
service (`alknet-agent`, downstream) is the consumer that orchestrates these
via `env.invoke()`.
## Implementation Priority Order
Based on the gap analysis and the downstream unblock chain:
1. **`CallClient`** (critical) — outbound connection opener. Without it, no
runner, no container service, no bilateral exchange. Reuses the existing
`CallConnection` for the dispatch loop; adds only the
connection-establishment + credential-handling half. The single
highest-value piece of work in the entire `alknet-call` completion.
2. **`from_call`** (critical, depends on `CallClient`) — consumes the
already-implemented `services/list` + `services/schema` discovery API.
3. **`OperationAdapter` trait** (enabling) — the async trait. Small,
standalone, unblocks `alknet-http` Phase 1.
4. **`from_jsonschema`** (medium, standalone) — schema-only registration, no
handler. Small.
5. **DC-1 resolution** (peer-scoped registry filtering, ADR-028) — the
security dimension of `CallClient`'s registry. Addressed in parallel with
#1 — it's a filtering layer on the registry the `CallClient` exposes, not
a blocker for the connection-establishment work.
## What This Completion Unblocks
| Downstream crate | What it needs from alknet-call | Status without completion |
|-------------------|-------------------------------|--------------------------|
| alknet-http | `OperationAdapter` trait (to implement `from_openapi`/`from_mcp`) | Blocked — can't define HTTP-backed adapters without the trait |
| alknet-ssh | Stable alknet-call types (no adapter dependency) | Not blocked — ssh depends on alknet-core, not alknet-call's adapters. Proceeds in parallel. |
| alknet-agent | `CallClient` (tool dispatch), `from_call` (remote tool import), `OperationAdapter` (provider adapters) | Blocked on `CallClient` + `from_call` |
| Container service (dispatch rewrite) | `CallClient` + `from_call` | Blocked — this is the primary consumer |
| Runner pattern (dev runner, opencode runner) | `CallClient` + `from_call` | Blocked — the runner IS a `CallClient` |
| alknet-napi | `CallClient` (Node.js calls remote ops) | Blocked — NAPI projects `CallClient` to JS |
## Constraints
- **No HTTP in alknet-call.** `from_openapi`/`from_mcp`/`to_openapi`/`to_mcp`
live in `alknet-http`. The `OperationAdapter` trait and the QUIC-backed
adapters (`from_call`, `from_jsonschema`) live in `alknet-call`. See
Adapter Location Map.
- **No secret material on the wire.** `CallCredentials` carries vault-derived
material for the *outbound* connection (TLS identity, auth token); the
call protocol's wire format carries no private keys, API keys, or decrypted
credentials (ADR-014). The no-env-vars invariant (above) is the dispatch-side
corollary.
- **Peer-scoped registry is default-deny.** A `CallClient` exposes no
operations to the remote peer unless marked remote-safe. Trusted-peer
opt-in is explicit (ADR-028).
- **`from_call` re-import is auto-on-reconnect.** v1 default; the overlay is
per-connection so re-import is naturally scoped (DC-2, OQ-27).
- **`from_call` namespace collision is an error.** Default no prefix; the
operator adds prefixes when importing from multiple sources (DC-3, OQ-28).
- **`OperationAdapter::import()` returns `Result`.** Failures surface as
`AdapterError` (DC-4, OQ-26).
- **MCP stdio transport is not built.** Streamable HTTP is the only supported
MCP transport in alknet. stdio = spawn arbitrary executable = built-in RCE.
Recorded as an explicit security position, not a feature gap.
## Design Decisions
| Decision | ADR | Summary |
|----------|-----|---------|
| Call protocol client and adapter contract | [ADR-017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | `CallClient` opens connections; `from_call` imports remote ops; connection direction independent of call direction; trait is async; adapters produce `HandlerRegistration` bundles |
| Peer-scoped registry filtering (DC-1) | [ADR-028](../../decisions/028-callclient-peer-scoped-registry-filtering.md) | Default-deny; `remote_safe: bool` on `HandlerRegistration`; trusted-peer opt-in; one-way door on the security dimension |
| Secret material flow and capability injection | [ADR-014](../../decisions/014-secret-material-flow-and-capability-injection.md) | The no-env-vars invariant's foundation; capabilities injected at assembly layer |
| Handler registration, provenance, and composition authority | [ADR-022](../../decisions/022-handler-registration-provenance-and-composition-authority.md) | The registration bundle adapters produce; `composition_authority: None` for leaves |
| Operation registry layering | [ADR-024](../../decisions/024-operation-registry-layering.md) | Layer 2 per-connection overlay where `from_call` imports land |
| Privilege model and authority context | [ADR-015](../../decisions/015-privilege-model-and-authority-context.md) | Adapter-registered ops are `Internal` by default; default-deny posture |
| Abort cascade for nested calls | [ADR-016](../../decisions/016-abort-cascade-for-nested-calls.md) | Cross-node abort through `from_call` forwarding handler's `parent_request_id` |
| Operation error schemas | [ADR-023](../../decisions/023-operation-error-schemas.md) | `error_schemas` mirrored by `from_call` from remote op's spec |
| TLS identity redesign | [ADR-027](../../decisions/027-tls-identity-redesign-acme-rawkey-decoupling.md) | RFC 7250 raw key / X.509 cert dimensions of `CallCredentials` |
| HD derivation for encryption keys | [ADR-020](../../decisions/020-hd-derivation-for-encryption-keys.md) | Vault-derived TLS identity material |
| Vault key model | [ADR-026](../../decisions/026-vault-key-model-hd-derivation.md) | Vault-derived TLS identity material |
| Vault local-only dispatch | [ADR-025](../../decisions/025-vault-local-only-dispatch.md) | Vault access at assembly layer only; the credential injection path's first hop |
| Crate decomposition | [ADR-003](../../decisions/003-crate-decomposition.md) | `alknet-http` depends on `alknet-call` (protocol-foundation exception, noted in Adapter Location Map) |
| One-way door decision framework | [ADR-009](../../decisions/009-one-way-door-decision-framework.md) | Door-type classification for DC-1..4 |
## Open Questions
See [open-questions.md](../../open-questions.md) for full details.
- **OQ-25** (open, two-way): Remote-safe marking shape — `remote_safe: bool`
v1 vs per-peer allowlist vs capability-class tag. The *existence* of
filtering is locked by ADR-028; the shape is the two-way-door remainder.
- **OQ-26** (open, two-way): `AdapterError` enum variants (DC-4). The
*presence* of an error type is recorded here; the variants are
implementation-detail.
- **OQ-27** (open, two-way): `from_call` re-import trigger — auto-on-reconnect
(v1 default, recorded here) vs explicit `CallConnection::refresh()`. v1 is
auto-on-reconnect; the explicit path is additive.
- **OQ-28** (open, two-way): `from_call` namespace collision behavior — error
on collision (v1 default, recorded here) vs last-wins.
## References
- ADR-017: Call Protocol Client and Adapter Contract (the spec this document
operationally fills)
- ADR-028: Peer-Scoped Registry Filtering for CallClient Inbound Dispatch
(resolves DC-1)
- `call-protocol.md` — `CallAdapter`, `CallConnection`, dispatch loop, stream
model (the server-side complement to this document)
- `operation-registry.md` — `HandlerRegistration`, provenance, capability
injection, service discovery (the discovery API `from_call` consumes)
- `docs/research/alknet-call-completion/gap-analysis.md` — DC-1..4, the
implementation-state audit, the downstream unblock chain
- `/workspace/@alkdev/operations/` — TypeScript prior art (`from_openapi.ts`,
`from_mcp.ts`, `from_schema.ts`, `scanner.ts`)
- `/workspace/@alkdev/dispatch/` — concrete downstream consumer (container
service / "reverse git runner") this completion unblocks
- `/workspace/aisdk/` — downstream consumer (Rust port of Vercel AI SDK); the
no-env-vars invariant makes its `std::env::var` reads unreachable
- `/workspace/rust-sdk/` — MCP Rust SDK (rmcp); streamable HTTP transport for
`alknet-http`'s `from_mcp`/`to_mcp` (separate crate, separate Phase 0)
- `docs/research/alknet-ssh/phase-0-findings.md` — alknet-ssh Phase 0;
confirms ssh depends on alknet-core not alknet-call's adapters, so it
proceeds in parallel with this completion

8
docs/architecture/crates/call/operation-registry.md
View File

@@ -232,6 +232,8 @@ pub struct HandlerRegistration {
pub composition_authority: Option<CompositionAuthority>, // None for leaves
pub scoped_env: Option<ScopedOperationEnv>, // None for leaves
pub capabilities: Capabilities,
pub remote_safe: bool, // default false; ADR-028 — exposes this op to
// CallClient peers (trusted-peer mode bypasses)
}
```
@@ -632,6 +634,8 @@ The `Capabilities` type holds non-serializable, zeroized secret material. It doe
**Scoped composition env.** The `OperationEnv` given to a handler is scoped — it can only invoke a declared set of operations, set at registration on the `HandlerRegistration` bundle by the assembly layer (ADR-022). This bounds the parameterized-dispatch attack surface: a handler (or an LLM picking tools, or a quickjs sandbox) can only reach declared operations, not the entire registry. The scoped env is the reachability control; the composition authority is the authority control. Both are needed for least privilege. See ADR-015 and ADR-022.
**No-env-vars invariant.** No handler reads outbound credentials from any source other than `OperationContext.capabilities`. This is the dispatch-side corollary of the capability-injection flow above: because the dispatch path populates `OperationContext.capabilities` from the registration bundle (ADR-022 §6), and because the assembly layer constructs handlers with vault-derived credentials rather than calling `Default::default()`, downstream consumers' `std::env::var` credential reads are unreachable by construction. The full invariant, the credential injection path, and the downstream-consumer framing are recorded in [client-and-adapters.md](client-and-adapters.md); this section documents the dispatch-path mechanism that makes it enforceable.
## Constraints
- The registry is **layered by trust boundary** (ADR-024). The curated layer (`Local` provenance) is immutable after construction — adding a `Local` op requires restarting the process, which re-enters the startup trust boundary. Session (`Session`) and imported (`FromCall` etc.) ops are dynamic at their respective scopes (per-session, per-connection). The pre-ADR-024 blanket immutability claim was inherited by analogy from ADR-010's `HandlerRegistry` (ALPN-level) and did not apply to the operation registry — the TLS-config argument that justifies `HandlerRegistry` immutability does not touch the operation registry, which lives behind the single ALPN `alknet/call`.
@@ -659,6 +663,8 @@ The `Capabilities` type holds non-serializable, zeroized secret material. It doe
| Handler registration, provenance, and composition authority | [ADR-022](../../decisions/022-handler-registration-provenance-and-composition-authority.md) | Registration bundle carries provenance, composition authority, scoped env, capabilities; dispatch path reads from bundle |
| Operation registry layering | [ADR-024](../../decisions/024-operation-registry-layering.md) | Curated (static, immutable) + session and connection overlays (dynamic); `OperationEnv` as trait-object integration point; `OperationContext.env` split into `scoped_env` (data) and `env` (dispatch trait) |
| Operation error schemas | [ADR-023](../../decisions/023-operation-error-schemas.md) | Operations declare domain errors; `call.error` carries typed `details`; adapter fidelity for `from_openapi`/`to_openapi` |
| Call protocol client and adapter contract | [ADR-017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | `from_call`/`from_jsonschema`/`OperationAdapter` produce `HandlerRegistration` bundles; adapter-registered ops are `Internal` leaves. Surface specced in [client-and-adapters.md](client-and-adapters.md) |
| Peer-scoped registry filtering for CallClient | [ADR-028](../../decisions/028-callclient-peer-scoped-registry-filtering.md) | Default-deny `CallClient` registry view; adds `remote_safe` marking to `HandlerRegistration` (the bundle this doc defines) |
## Open Questions
@@ -668,6 +674,8 @@ See [open-questions.md](../../open-questions.md) for full details.
- **OQ-14** (resolved): Batch is a client-side pattern of correlated `call.requested` events, not a protocol primitive.
- **OQ-16** (resolved by ADR-014): No vault operations are exposed over the call protocol for now.
- **OQ-19** (resolved): Session-scoped operation registries — agent-written operations overlaid on the curated registry via `OperationEnv` trait layering. Protocol doesn't need changes; `OperationEnv` must remain a trait. Session ops are `Session` provenance (ADR-022) — always `Internal`, compose under restricted authority scoped down at sandbox creation. Generalized by ADR-024 to cover connection-scoped overlays as well.
- **OQ-25** (open, two-way): Remote-safe marking shape — existence of default-deny `CallClient` filtering locked by ADR-028; the shape (the `remote_safe: bool` field this doc's `HandlerRegistration` gains vs a richer per-peer mechanism) is the two-way-door remainder. See [client-and-adapters.md](client-and-adapters.md).
- **OQ-26..28** (open, two-way): `OperationAdapter` error type, `from_call` re-import trigger, `from_call` namespace collision. v1 defaults recorded in [client-and-adapters.md](client-and-adapters.md).
## References

70
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View File

@@ -2,7 +2,7 @@
## Status
Accepted
Accepted (amended 2026-06-26 — see "Amendments" below)
## Context
@@ -336,9 +336,77 @@ same as `from_openapi` receives HTTP credentials.
- ADR-014: Secret material flow (credential sources, not static tokens)
- ADR-015: Privilege model (adapter ops are Internal by default)
- ADR-016: Abort cascade (cross-node abort propagation)
- ADR-028: Peer-Scoped Registry Filtering for CallClient Inbound Dispatch
(resolves the §1 Consequences security dimension flagged as a two-way door)
- OQ-15: Call protocol client and adapter contract (resolved by this ADR)
- OQ-25..28: Two-way-door remainders from the call-completion gap analysis
(DC-1 shape, DC-4 error type, DC-2 re-import trigger, DC-3 namespace
collision — see [open-questions.md](../open-questions.md))
- [call-protocol.md](../crates/call/call-protocol.md)
- [operation-registry.md](../crates/call/operation-registry.md)
- [client-and-adapters.md](../crates/call/client-and-adapters.md) — the spec
that operationally fills the gap this ADR left to implementation
- `docs/research/alknet-call-completion/gap-analysis.md` — DC-1..4, the
decisions that needed resolution before implementation
- TypeScript `@alkdev/operations` — `from_openapi`, `from_mcp`, `buildEnv`
prior art
- POC at `/workspace/@alkdev/dispatch` — head/worker dispatch over SSH+axum
## Amendments (2026-06-26)
This ADR left four decisions as two-way doors (§1 Consequences flagged DC-1's
security dimension; §5 noted trait signatures are two-way doors; Assumption 4
noted re-import hot-swap is a two-way door; §3 mentioned the namespace prefix).
The call-completion gap analysis (`docs/research/alknet-call-completion/gap-analysis.md`
DC-1..4) resolved them. The resolutions:
### DC-1 — CallClient registry scope: resolved by ADR-028
The §1 Consequences security dimension is resolved by
[ADR-028](028-callclient-peer-scoped-registry-filtering.md). The one-way
door (existence of peer-scoped filtering as the v1 default) is locked:
**default-deny**, with a `remote_safe: bool` on `HandlerRegistration`
v1 shape and a trusted-peer opt-in. The shape of the marking is the
two-way-door remainder, tracked as OQ-25. This ADR's §1 text ("It has its own
operation registry to dispatch incoming calls from the remote side") and
the Consequences note ("The specific mechanism … is a two-way door") are
superseded by ADR-028's decision that the *default* is filtered, not
shared-global. Share-global remains available as the explicit opt-in
(ADR-028 §3).
### DC-4 — OperationAdapter trait error type: resolved
§5 showed `async fn import(&self) -> Vec<HandlerRegistration>` with no error
type. The trait returns `Result<Vec<HandlerRegistration>, AdapterError>`
where `AdapterError` is a crate-level enum. The *presence* of the error type
is recorded in [client-and-adapters.md](../crates/call/client-and-adapters.md);
the exact variants are the two-way-door remainder, tracked as OQ-26.
### DC-2 — from_call re-import on reconnection: default set
Assumption 4 noted re-import "happens on reconnection or is triggered
explicitly." The v1 default is **auto-re-import on connection establishment**.
The overlay is per-connection (Layer 2, ADR-024), so re-import is naturally
scoped; a stale overlay dies with the connection. Explicit re-import via a
future `CallConnection::refresh()` is additive. Two-way door; recorded in
[client-and-adapters.md](../crates/call/client-and-adapters.md); tracked as
OQ-27.
### DC-3 — from_call namespace collision: default set
§3's `FromCallConfig` namespace prefix is **optional, default no prefix,
collision = error**. A node importing from two remotes that both expose the
same unprefixed op name should fail loudly. The operator adds prefixes when
importing from multiple sources. Two-way door; recorded in
[client-and-adapters.md](../crates/call/client-and-adapters.md); tracked as
OQ-28.
### Operational spec
The gap this ADR left to implementation — the `CallClient` API, the
`from_call`/`from_jsonschema` flows, the trait signature, the adapter
location map, the no-env-vars invariant, and the exchange-of-operations
pattern — is specified in
[client-and-adapters.md](../crates/call/client-and-adapters.md). That document
is the operational complement to this ADR; this ADR remains the architectural
authority.

215
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@@ -0,0 +1,215 @@
# ADR-028: Peer-Scoped Registry Filtering for CallClient Inbound Dispatch
## Status
Accepted
## Context
ADR-017 §1 established that a `CallClient` — which opens an outbound
`alknet/call` connection — "has its own operation registry to dispatch incoming
calls from the remote side." The ADR left the *registry scope* as an explicit
two-way door in its Consequences:
> Sharing the global registry with a `CallClient` exposes local capabilities to
> the remote peer… A peer-scoped subset must filter by capability
> remote-safety, not just operation name. The registry-mechanism choice
> (share global vs subset vs separate) is two-way mechanically but has a
> security dimension post-ADR-022: the "share global" option is a
> capability-exposure decision, not just a dispatch decision.
This is the one decision identified in
`docs/research/alknet-call-completion/gap-analysis.md` (DC-1) that must be
locked before `CallClient` can be implemented correctly. It is a **one-way door
on the security dimension**: the choice of default determines what a remote peer
can reach, and a wrong default silently exposes outbound credentials.
### Why this is a one-way door, not a two-way door
The gap analysis framed the *mechanism* (share-global vs subset vs separate
registry instance) as a two-way door, and that framing holds. But the
**existence of peer-scoped filtering as the v1 default** is one-way, because:
1. Once a downstream consumer (the runner pattern, the container service, the
NAPI projection) is written against the "remote peer can call any
`External` op and the local node's capabilities will be populated for it"
semantics, switching the default to default-deny is a breaking change for
every consumer. The container-service rewrite at `/workspace/@alkdev/dispatch`
and the dev/runner patterns are the first consumers; the default is set
before they're written, so it's still cheap to set correctly — but only now.
2. The security dimension is asymmetric in ADR-009 terms. "Share global" leaks
silently: there is no error, no log line, no test that fails — the remote
peer simply receives a populated `OperationContext.capabilities` drawn from
the local `HandlerRegistration.capabilities`, and the local node's API keys
get used for the remote peer's call. The reversal cost is "discover which
consumers quietly depend on the leak and re-audit." Default-deny fails
loudly (the remote peer's call to an unexposed op returns `NOT_FOUND`),
which is the cheaper failure mode.
3. ADR-014's invariant — "no handler reads outbound credentials from any
source other than `OperationContext.capabilities`" — combined with
ADR-022's dispatch path (which populates `capabilities` from the
registration bundle) means the registration bundle *is* the exposure
boundary. Whatever the `CallClient` dispatches determines which
`Capabilities` objects cross to the remote peer's call context. Filtering
the registry is filtering capability exposure.
### The runner/dispatch pattern is the primary use case, and it is semi-trusted
The canonical consumer (gap analysis §"Exchange of Operations"): a container
service / dev runner connects *outward* to a hub and exposes `/container/exec`,
`/container/list`, etc. The hub then calls back into the runner. Both sides
are semi-trusted peers, not extensions of self. Exposing every `External`
operation on the runner — including any operation that carries an outbound
API key the runner happens to hold — is wrong by default. The operator who
*does* want full bilateral sharing is making an explicit trust decision.
## Decision
### 1. Default-deny: a CallClient exposes no operations to the remote peer unless explicitly marked remote-safe
The `CallClient` does not share the global `OperationRegistry` by default. It
holds a **peer-scoped subset**: a filtered view containing only
`HandlerRegistration`s that are explicitly marked as remote-safe for this peer.
The *existence* of filtering is the one-way door; this ADR locks it.
### 2. The remote-safe marking lives on the registration bundle, not on capabilities
The marking is added to `HandlerRegistration` (per ADR-022, the registration
bundle) as a peer-exposure field. It is not placed on `Capabilities` entries,
because:
- `Capabilities` is a flat credential bag; marking individual entries
remote-safe conflates "this credential is safe to send over the wire" with
"this operation may be dispatched on behalf of a remote peer." Those are
different questions — an operation may be remote-safe while using a
credential that must never leave the node, and the dispatch path already
keeps `Capabilities` off the wire (ADR-014). The exposure question is about
*which ops dispatch*, not *which credentials are serializable*.
- The registration bundle is already the integration point for provenance,
composition authority, scoped env, and visibility (ADR-022). Peer-exposure is
a property of the same shape: a dispatch-path concern set at registration.
The exact shape of the marking (a boolean, a per-peer allowlist, a
capability-class tag) is the two-way-door remainder — tracked as OQ-25, not
decided here. v1 uses the simplest shape that supports default-deny: a boolean
`remote_safe: bool` on `HandlerRegistration`, defaulting to `false`.
### 3. "Share the global registry" remains available as an explicit opt-in
A `CallClient` may be constructed in "trusted-peer" mode that exposes all
`External` operations from the global registry regardless of the remote-safe
marking. This is the explicit-allow path for operators who have made the trust
decision (e.g., two nodes under single administrative control, a test harness).
It is opt-in, never the default.
### 4. Provenance-based defaults
The remote-safe marking has a provenance-aware default at registration time,
before the operator's explicit choice:
| Provenance | Default `remote_safe` |
|-----------|----------------------|
| `Local` | `false` — assembly-written ops are not remote-callable unless the operator says so |
| `Session` | `false` — agent-written ops are sandboxed (ADR-015); exposing them to a remote peer would widen the sandbox |
| `FromOpenAPI`, `FromMCP`, `FromCall`, `FromJsonSchema` | `false` — leaves are composition material, not wire-callable (ADR-015) |
`false` across the board as the default. The operator flips specific
operations to `true` when they want this peer to reach them. This is the same
default-deny posture as ADR-015's visibility (`Internal` by default) and
ADR-022's composition authority (`None` for leaves by default).
### 5. The filtering is a dispatch-time read, not a copy
The `CallClient`'s peer-scoped view is not a second copy of the registry. It
is a dispatch-time read against the global registry, gated by the remote-safe
marking (and the trusted-peer flag). This keeps the curated layer (Layer 0,
ADR-024) single-source — the global registry is still the one Layer-0 store
built by the assembly layer at startup. Only the *visibility* to the remote
peer is filtered.
This avoids a third registry instance (the "separate registry per CallClient"
option from DC-1) and avoids the staleness problem a copied subset would
introduce: if the assembly layer reloads a curated op's spec, the peer-scoped
view reflects it on the next dispatch, not on the next copy.
## Consequences
**Positive:**
- The default is safe-by-construction for the runner/dispatch pattern. A
container service that connects outward to a hub cannot accidentally expose
its local vault-derived API keys to the hub's calls.
- The one-way security door is locked before any consumer is written against
the leaky default. The container-service rewrite and the dev/runner patterns
implement against default-deny from day one.
- Failure mode is loud: a remote peer calling an unexposed op gets
`NOT_FOUND`, not silent credential exposure.
- The mechanism is additive. Trusted-peer opt-in preserves the "share global"
path for operators who want it, without making it the default.
- Single-source Layer 0: no copied registry, no staleness.
**Negative:**
- Adds one field (`remote_safe: bool`) to `HandlerRegistration` (ADR-022).
The registration bundle grows. This is the smallest shape that supports
default-deny; OQ-25 may replace it with a richer mechanism (per-peer
allowlists, capability-class tags).
- Operators must explicitly mark operations remote-safe for bilateral
exchange. This is friction, deliberately: the bilateral container-service
pattern requires the operator to declare which of the runner's ops the hub
may call back into.
- The remote-safe marking is a v1 mechanism and may be superseded. OQ-25
tracks the shape; a future ADR may amend or supersede this one without
revisiting the *existence* of filtering.
- The trusted-peer opt-in is a sharp tool. An operator who enables it for the
wrong peer gets the "share global" exposure this ADR exists to prevent.
The opt-in is documented as a trust decision, not as a convenience.
## Assumptions
1. **The remote-safe marking is set at registration time, not at connection
time.** The marking is a property of the operation (per-peer in a richer
shape, but at least a boolean in v1), set by the assembly layer when it
builds the registry. Per-connection overrides are not part of v1; if a
deployment needs different exposure per peer, it uses the richer shape
(OQ-25) or multiple `CallClient`s with different filtered views.
2. **The peer-scoped view filters dispatch, not `services/list` semantics.**
The remote peer discovers operations via `services/list` (ADR-017 §3),
which already filters by `Visibility::External` (ADR-015). The remote-safe
marking is an *additional* filter for the dispatch path: an op may be
`External` yet not remote-safe. In v1, `services/list` served to a
`CallClient` peer **hides** non-remote-safe ops — a peer should not see
ops it cannot call, so discovery and dispatch filters agree. (The
pre-filter mental model — "`External` appears in `services/list`, then
the dispatch path returns `NOT_FOUND` for non-remote-safe" — is *not* the
v1 behavior; v1 hides them from listing too.) Whether a richer shape
(OQ-25) should expose-but-deny instead of hide is a two-way-door detail
tracked in OQ-25.
3. **Filtering is per-`CallClient`, not global.** A node with multiple
outbound connections may expose different subsets to different peers. The
v1 boolean marking limits this to "remote-safe for any peer" vs "not"; the
richer OQ-25 shape is what enables per-peer differentiation. v1's
limitation is acceptable because the runner/dispatch pattern has one
remote peer per `CallClient`.
## References
- ADR-009: One-Way Door Decision Framework (the door-type framing this ADR
relies on)
- ADR-014: Secret Material Flow and Capability Injection (the no-env-vars
invariant this ADR's security argument rests on)
- ADR-015: Privilege Model and Authority Context (the default-`Internal`,
default-deny posture this ADR mirrors)
- ADR-017: Call Protocol Client and Adapter Contract (§1 Consequences flagged
this decision; §1 is amended by this ADR)
- ADR-022: Handler Registration, Provenance, and Composition Authority (the
registration bundle this ADR adds a field to)
- ADR-024: Operation Registry Layering (Layer 0 single-source; the peer-scoped
view is a dispatch-time read, not a copy)
- OQ-25: Remote-safe marking shape (the two-way-door remainder)
- `docs/research/alknet-call-completion/gap-analysis.md` — DC-1
- `docs/architecture/crates/call/client-and-adapters.md` — the spec this ADR
informs

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@@ -1,6 +1,6 @@
---
status: draft
last_updated: 2026-06-20
last_updated: 2026-06-26
---
# Open Questions
@@ -316,3 +316,96 @@ These questions are acknowledged but not active. They will be promoted to open w
- **Priority**: high
- **Resolution**: `OperationSpec` gains `error_schemas: Vec<ErrorDefinition>` where each `ErrorDefinition` carries a `code`, `description`, `schema` (JSON Schema for the error detail payload), and optional `http_status` (for adapter projection). The `call.error` payload gains an optional `details` field carrying the typed error payload. Protocol-level codes (`NOT_FOUND`, `FORBIDDEN`, `INVALID_INPUT`, `INTERNAL`, `TIMEOUT`) are distinct from operation-level domain codes (`FILE_NOT_FOUND`, `RATE_LIMITED`, etc.) — protocol codes are emitted by the dispatch machinery, operation codes by handlers. `from_openapi`/`to_openapi` map OpenAPI response status codes to/from `ErrorDefinition`s, making the adapter contract from ADR-017 faithful on the error axis. `services/schema` exposes `error_schemas` for client code generation. See ADR-023.
- **Cross-references**: ADR-017, ADR-023, docs/reviews/001-pre-implementation-architecture-sanity-check.md (C5), [operation-registry.md](crates/call/operation-registry.md), [call-protocol.md](crates/call/call-protocol.md)
## Theme: Call Client and Adapters
These open questions are the two-way-door remainders from the
call-completion gap analysis
(`docs/research/alknet-call-completion/gap-analysis.md`, DC-1..4). The
one-way door among them (DC-1, the *existence* of peer-scoped filtering as
the default) is resolved by ADR-028; what remains open here is the shape.
The v1 defaults for DC-2/3/4 are recorded in
[client-and-adapters.md](crates/call/client-and-adapters.md) and may be
revisited during implementation without a new ADR.
### OQ-25: Remote-Safe Marking Shape for CallClient Peer-Scoped Filtering
- **Origin**: [client-and-adapters.md](crates/call/client-and-adapters.md), ADR-017 (§1 Consequences), ADR-028
- **Status**: open
- **Door type**: Two-way (shape only — existence is one-way, resolved by ADR-028)
- **Priority**: medium
- **Resolution**: ADR-028 locks the one-way door: a `CallClient`'s registry
view is **default-deny** (no operation is exposed to the remote peer unless
explicitly marked remote-safe), with share-global as an explicit trusted-peer
opt-in. The v1 shape is a `remote_safe: bool` field on
`HandlerRegistration` (default `false` across all provenance). The shape is
the two-way-door remainder: a boolean is the simplest shape that supports
default-deny; a deployment that needs per-peer differentiation (different
subsets exposed to different peers on the same node) needs a richer
mechanism — per-peer allowlist, capability-class tag, or a peer-id-keyed map
on the registration. v1's boolean limits this to "remote-safe for any peer"
vs "not", which is acceptable for the runner/dispatch pattern (one remote
peer per `CallClient`). A future ADR may amend or supersede ADR-028's shape
without revisiting the *existence* of filtering. Also open under this OQ:
whether a richer shape should *expose-but-deny* non-remote-safe ops in
`services/list` (returning `NOT_FOUND` on call) instead of *hiding* them.
v1 hides them — a peer should not see ops it cannot call, so discovery and
dispatch filters agree (ADR-028 Assumption 2); expose-but-deny is the
richer-shape question, not a v1 question.
- **Cross-references**: ADR-009, ADR-014, ADR-015, ADR-017, ADR-022, ADR-024,
ADR-028, [client-and-adapters.md](crates/call/client-and-adapters.md),
[operation-registry.md](crates/call/operation-registry.md)
### OQ-26: OperationAdapter Error Type (AdapterError Variants)
- **Origin**: [client-and-adapters.md](crates/call/client-and-adapters.md), ADR-017 §5
- **Status**: open
- **Door type**: Two-way
- **Priority**: medium
- **Resolution**: ADR-017 §5 showed `async fn import(&self) ->
Vec<HandlerRegistration>` with no error type. The trait returns
`Result<Vec<HandlerRegistration>, AdapterError>` where `AdapterError` is a
crate-level enum. The *presence* of an error type is recorded in
[client-and-adapters.md](crates/call/client-and-adapters.md); the exact
variants are the two-way-door remainder. The failure modes real
implementations hit: discovery transport failure (`from_call` remote
unreachable), schema parse failure (`from_openapi`, `from_jsonschema`),
unauthorized (HTTP 401 for `from_openapi`, `from_mcp`). Likely variants:
`DiscoveryFailed`, `SchemaParse`, `Transport`, `Unauthorized`. Decided
during implementation; recorded here, not in a full ADR.
- **Cross-references**: ADR-017, [client-and-adapters.md](crates/call/client-and-adapters.md)
### OQ-27: from_call Re-Import Trigger
- **Origin**: [client-and-adapters.md](crates/call/client-and-adapters.md), ADR-017 Assumption 4
- **Status**: open
- **Door type**: Two-way
- **Priority**: low
- **Resolution**: ADR-017 Assumption 4 noted re-import "happens on
reconnection or is triggered explicitly." The v1 default is
**auto-re-import on connection establishment**. The overlay is
per-connection (Layer 2, ADR-024), so a stale overlay dies with the
connection; re-import on reconnect is naturally scoped to the new
connection. This is the right default for the runner pattern (a worker
reconnects → the hub re-discovers the worker's ops automatically).
Explicit re-import via a future `CallConnection::refresh()` method is
additive and can be added if a deployment needs manual control. Reversal
is cheap; no ADR needed.
- **Cross-references**: ADR-017, ADR-024, [client-and-adapters.md](crates/call/client-and-adapters.md)
### OQ-28: from_call Namespace Collision Behavior
- **Origin**: [client-and-adapters.md](crates/call/client-and-adapters.md), ADR-017 §3
- **Status**: open
- **Door type**: Two-way
- **Priority**: low
- **Resolution**: ADR-017 §3's `FromCallConfig` namespace prefix is
**optional, default no prefix, collision = error**. A node importing from
two remotes that both expose `/container/exec` without prefixes should fail
loudly rather than silently overwrite. The operator adds prefixes when they
know they're importing from multiple sources. This matches the
default-deny, explicit-allow posture (ADR-015, ADR-028). Reversal is cheap;
no ADR needed. The alternative (last-wins) would silently mask one
remote's op behind another's, which is the kind of surprise the
default-deny posture exists to avoid.
- **Cross-references**: ADR-015, ADR-017, ADR-028, [client-and-adapters.md](crates/call/client-and-adapters.md)

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---
id: call/client/call-client
name: Implement CallClient (outbound connection opener) with peer-scoped default-deny dispatch (ADR-017, ADR-028)
status: pending
depends_on: [call/protocol/call-connection, call/registry/remote-safe-marking]
scope: moderate
risk: high
impact: phase
level: implementation
---
## Description
Implement `CallClient` in `src/client/mod.rs` (new `client` module). This is
the #1 gap in alknet-call — the outbound connection opener. Every downstream
consumer (runner pattern, container service, bilateral exchange, NAPI
projection, agent cross-node tool dispatch) is blocked on it. It opens a QUIC
connection to a remote node on ALPN `alknet/call`, performs credential setup,
and produces a `CallConnection` running the **shared** dispatch loop (ADR-017
§1). `CallClient` is the connection-establishment half; `CallAdapter`'s
accept path is the inbound half. Both produce the same `CallConnection`.
### CallClient struct
```rust
pub struct CallClient {
/// The operation registry. The peer-scoped view is a dispatch-time read
/// over this registry, not a copy (ADR-028 §5).
registry: Arc<OperationRegistry>,
identity_provider: Arc<dyn IdentityProvider>,
/// Trusted-peer mode (ADR-028 §3): when true, the dispatch path exposes
/// all External ops to the remote peer and services/list lists all
/// External ops, ignoring the remote_safe marking. When false (default),
/// only registrations with remote_safe: true dispatch, and services/list
/// hides non-remote-safe ops (ADR-028 Assumption 2).
trusted_peer: bool,
}
impl CallClient {
/// Default: peer-scoped (default-deny). Filters dispatch + services/list
/// by remote_safe == true.
pub fn new(registry: Arc<OperationRegistry>, idp: Arc<dyn IdentityProvider>) -> Self;
/// Trusted-peer mode: expose all External ops, ignore remote_safe.
/// Explicit opt-in per ADR-028 §3.
pub fn trusted_peer(registry: Arc<OperationRegistry>, idp: Arc<dyn IdentityProvider>) -> Self;
/// Open a QUIC connection to `addr` on ALPN `alknet/call`, perform
/// credential handshake, and return a CallConnection running the shared
/// dispatch loop. Credentials come from capabilities (ADR-014), not env
/// vars — see client-and-adapters.md "No-Env-Vars Invariant".
pub async fn connect(
&self,
addr: SocketAddr,
credentials: CallCredentials,
) -> Result<CallConnection, ClientError>;
}
```
### Shared dispatch loop
The dispatch loop is **shared** with `CallAdapter`. Once a connection is
established (whether accepted or opened), the same logic applies: read
`EventEnvelope` frames, dispatch to the operation registry, write responses,
send outgoing `call.requested` for calls initiated on this side. Refactor the
existing accept-path dispatch out of `CallAdapter` into a shared function
(likely in `src/protocol/connection.rs` or a new `src/protocol/dispatch.rs`)
that both `CallAdapter::handle` and `CallClient::connect` call. Do not
duplicate the dispatch loop — ADR-017 §1 is explicit that the client is the
connection-establishment half, not a parallel protocol implementation.
The `CallConnection` type already exists (`protocol/connection.rs`) and
holds the Layer 2 overlay + call/subscribe/abort API. `CallClient::connect`
constructs it from the opened connection (vs `CallAdapter` constructing it
from the accepted connection).
### Peer-scoped dispatch (ADR-028 — default-deny)
The incoming-call dispatch path in the `CallClient` must filter by
`remote_safe`:
- **Default mode** (`trusted_peer: false`): an incoming `call.requested` for
an op name resolves to the registration; if `registration.remote_safe ==
false`, return `NOT_FOUND` (not `FORBIDDEN` — same posture as
`Visibility::Internal` per ADR-015). If `true`, dispatch normally.
`OperationContext.capabilities` is populated from the registration bundle
only for remote-safe ops — this is the security argument for default-deny
(ADR-028 Context): a remote peer's call must not trigger dispatch that
populates capabilities from the local node's registration bundle unless the
op is explicitly exposed.
- **Trusted-peer mode** (`trusted_peer: true`): bypass the `remote_safe`
filter; expose all `External` ops. The operator has made the trust decision
explicitly.
This is a dispatch-time read over the single Layer-0 registry (ADR-028 §5) —
not a copied subset, not a third registry instance. The `OperationRegistry`
from `remote-safe-marking` is the single source.
### services/list hide behavior (ADR-028 Assumption 2)
When the `CallClient` serves `services/list` to the remote peer:
- **Default mode**: hide ops where `remote_safe == false` (in addition to
the existing `Visibility::External` filter). A peer should not see ops it
cannot call.
- **Trusted-peer mode**: list all `External` ops regardless of
`remote_safe`.
The existing `services_list_handler` in `registry/discovery.rs` filters by
`Visibility::External` only. Wire the additional `remote_safe` filter for the
`CallClient`'s serving path. (The `CallAdapter`'s serving path — local
accept — is unchanged; it continues to list all `External` ops, since a
direct QUIC client is not a `CallClient` peer in the filtered sense. Clarify
this split in code comments and a test.)
### Credentials
`connect()` takes a `CallCredentials` bundle. Credentials come from
`Capabilities` (ADR-014), never env vars. The three dimensions (ADR-017 §7):
TLS identity (RFC 7250 raw key or X.509, ADR-027), auth token (opaque,
vault-decrypted), remote identity verification (expected fingerprint/cert).
Populated by the assembly layer at `CallClient` construction time from
vault-derived `Capabilities`. The concrete `TlsIdentity` / `AuthToken` /
`RemoteIdentity` shapes are implementation-detail two-way doors (recorded in
client-and-adapters.md); the one-way constraint is they come from
capabilities, not env vars.
### Connection symmetry
After establishment, the connection is symmetric (ADR-017 §2): both sides
can send and receive `call.requested`. Connection direction is independent of
call direction. The `CallClient` is both a caller (initiates outgoing calls
via `CallConnection::call()`/`subscribe()`/`abort()`) and a callee
(dispatches incoming calls against its peer-scoped view).
## Acceptance Criteria
- [ ] `src/client/mod.rs` exists with `CallClient` struct (registry, idp, trusted_peer)
- [ ] `CallClient::new` constructs default-deny (trusted_peer: false)
- [ ] `CallClient::trusted_peer` constructs trusted-peer mode
- [ ] `connect()` opens a QUIC connection on ALPN `alknet/call`
- [ ] `connect()` returns a `CallConnection` running the shared dispatch loop
- [ ] Dispatch loop is shared with `CallAdapter` (refactored, not duplicated)
- [ ] Default mode: incoming call to op with `remote_safe == false` returns NOT_FOUND
- [ ] Default mode: incoming call to op with `remote_safe == true` dispatches
- [ ] Default mode: capabilities populated only for remote-safe dispatched ops
- [ ] Trusted-peer mode: all External ops dispatch regardless of remote_safe
- [ ] Default mode: services/list hides non-remote-safe ops from the peer
- [ ] Trusted-peer mode: services/list lists all External ops
- [ ] Outgoing call()/subscribe()/abort() work through the returned CallConnection
- [ ] Connection symmetry: remote peer can call back into the CallClient
- [ ] `CallCredentials` carries TLS identity / auth token / remote identity (from capabilities)
- [ ] No env-var reads in the credential path (no-env-vars invariant, ADR-014)
- [ ] Integration test: two-node call (CallClient connects to CallAdapter, both call each other)
- [ ] Integration test: default-deny op returns NOT_FOUND to remote peer
- [ ] Integration test: remote_safe op dispatches to remote peer
- [ ] Integration test: trusted-peer mode exposes all External ops
- [ ] Integration test: services/list hides non-remote-safe in default mode
- [ ] `cargo test -p alknet-call` succeeds
- [ ] `cargo clippy -p alknet-call --all-targets` succeeds with no warnings
## References
- docs/architecture/crates/call/client-and-adapters.md — CallClient §, credential sources §
- docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md — ADR-017 §1 (shared loop), §2 (symmetry), §7 (credentials)
- docs/architecture/decisions/028-callclient-peer-scoped-registry-filtering.md — ADR-028 (default-deny, trusted-peer, Assumption 2 services/list hide)
- docs/architecture/crates/call/call-protocol.md — CallConnection (the type connect() produces)
- tasks/call/protocol/call-connection.md — completed CallConnection task
- tasks/call/registry/remote-safe-marking.md — prerequisite (adds remote_safe field)
- docs/research/alknet-call-completion/gap-analysis.md — DC-1, implementation priority #1
## Notes
> This is the single highest-value piece of work in the alknet-call
> completion — every downstream consumer is blocked on it. The dispatch loop
> is shared with CallAdapter (refactor, don't duplicate — ADR-017 §1 is
> explicit). The peer-scoped default-deny (ADR-028) is the one-way-door
> security dimension: a remote peer's call must not populate
> OperationContext.capabilities from the local bundle unless the op is
> explicitly remote-safe. The v1 shape is `trusted_peer: bool` + the
> `remote_safe: bool` field from `remote-safe-marking`; per-peer allowlists
> are OQ-25 and explicitly out of scope. Credentials come from capabilities,
> never env vars (no-env-vars invariant).

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---
id: call/client/from-call
name: Implement from_call adapter (discover remote ops via services/list + services/schema, register FromCall leaves)
status: pending
depends_on: [call/client/call-client]
scope: moderate
risk: medium
impact: component
level: implementation
---
## Description
Implement `from_call` in `src/client/from_call.rs`. This is the #2 gap — it
discovers the remote peer's `External` operations and registers them in the
connection's Layer 2 overlay as `FromCall`-provenance leaves with forwarding
handlers. The discovery mechanism (`services/list` + `services/schema`) is
already implemented in `registry/discovery.rs`; `from_call` is the
client-side consumer of that API.
### Flow (ADR-017 §3)
1. Call `services/list` on the remote → list of `External` operations.
2. Call `services/schema` for each → input/output JSON Schemas and declared
`error_schemas` (ADR-023).
3. For each discovered op, construct a `HandlerRegistration`:
- `spec` mirrors the remote op's name (with optional prefix), namespace,
type, schemas, access control.
- `handler` is a forwarding handler: sends `call.requested` through the
`CallConnection`, awaits `call.responded` (or streams for subscriptions).
- `provenance: FromCall`, `composition_authority: None`, `scoped_env: None`
(leaf — ADR-022).
4. The caller registers the bundles via
`CallConnection::register_imported_all()`.
### API
```rust
pub struct FromCallConfig {
/// Namespace prefix applied to imported operation names. Optional —
/// default no prefix. Collision on import is an error (DC-3, OQ-28),
/// not last-wins.
pub namespace_prefix: Option<String>,
/// Optional filter — import only operations whose names match. None
/// imports all External ops discovered via services/list.
pub operation_filter: Option<HashSet<String>>,
}
/// Discover the remote peer's External ops and construct HandlerRegistration
/// bundles with FromCall provenance and forwarding handlers. The caller
/// registers the bundles in the connection's overlay via
/// CallConnection::register_imported_all().
pub async fn from_call(
connection: &CallConnection,
config: FromCallConfig,
) -> Result<Vec<HandlerRegistration>, AdapterError>;
```
### Forwarding handler
The handler captures a handle to the `CallConnection` and, on invocation:
- For a `Query`/`Mutation` op: calls `connection.call(imported_name, input)`,
returns the `ResponseEnvelope`.
- For a `Subscription` op: calls `connection.subscribe(imported_name, input)`,
yields each `call.responded` until `call.completed`/`call.aborted`.
- The handler's `parent_request_id` participates in the abort cascade
(ADR-016 §6) — if the parent is aborted, the cascade reaches this handler,
which sends `call.aborted` to the remote node; the remote node cascades to
its own descendants. Cross-node abort is transparent.
### Re-import on reconnection (DC-2, OQ-27)
v1 default: `from_call` runs **automatically on connection establishment**.
The overlay is per-connection (Layer 2, ADR-024), so a stale overlay dies with
the connection; re-import on reconnect is naturally scoped to the new
connection. This is the right default for the runner pattern (a worker
reconnects → the hub re-discovers the worker's ops automatically). Wire the
auto-re-import into the `CallClient::connect` path (or document that the
assembly layer calls `from_call` immediately after `connect()` — pick the
cleaner integration; the auto-on-reconnect behavior is the v1 contract).
Explicit re-import via a future `CallConnection::refresh()` is additive
(OQ-27); do not implement `refresh()` in this task unless the auto-import
wiring naturally produces it.
### Namespace collision (DC-3, OQ-28)
v1 default: **optional prefix, default no prefix, collision = error**. A node
importing from two remotes that both expose `/container/exec` without
prefixes should fail loudly (return `AdapterError`) rather than silently
overwrite. The operator adds prefixes when importing from multiple sources.
Implement collision detection: if applying the (possibly empty) prefix
produces a name that already exists in the target overlay, return an error.
This matches the default-deny, explicit-allow posture (ADR-015, ADR-028).
### Provenance and visibility
`from_call`-registered operations are `Internal` by default (ADR-015) —
composition material, not directly callable from the wire. The handler that
composes them is `External`. Set `remote_safe: false` on FromCall leaves
(they're leaves — they don't expose to *their* peers; the composition
authority is `None`).
### Trust is transitive
A `from_call`-imported operation executes the remote node's code, not yours.
The scoped env (ADR-015) bounds *which* operations are reachable, not *what*
they do. `from_call` means "I trust the remote node as much as my own
handlers." This is inherent to remote composition; the spec records it, the
implementation doesn't need to enforce it beyond the scoped-env reachability
that already exists.
## Acceptance Criteria
- [ ] `src/client/from_call.rs` exists with `FromCallConfig` and `from_call`
- [ ] `from_call` calls `services/list` then `services/schema` for each op
- [ ] Each discovered op becomes a `HandlerRegistration` with `provenance: FromCall`
- [ ] Forwarding handler sends `call.requested` via `CallConnection::call`/`subscribe`
- [ ] Subscription forwarding yields until `call.completed`/`call.aborted`
- [ ] `composition_authority: None`, `scoped_env: None` for FromCall leaves
- [ ] `remote_safe: false` on FromCall leaves
- [ ] Namespace prefix applied when `config.namespace_prefix` is Some
- [ ] Collision on import (same prefixed name) returns `AdapterError`, not silent overwrite
- [ ] `operation_filter` limits which ops are imported
- [ ] Re-import runs on connection establishment (auto-on-reconnect, v1 default)
- [ ] Cross-node abort: parent abort cascades to from_call handler → sends call.aborted remote
- [ ] `from_call` returns `Result<_, AdapterError>` (the error type from OQ-26)
- [ ] Integration test: from_call populates Layer 2 overlay with remote External ops
- [ ] Integration test: forwarding handler invokes remote op and returns result
- [ ] Integration test: subscription forwarding streams remote events
- [ ] Integration test: namespace collision returns error
- [ ] Integration test: operation_filter limits imports
- [ ] `cargo test -p alknet-call` succeeds
- [ ] `cargo clippy -p alknet-call --all-targets` succeeds with no warnings
## References
- docs/architecture/crates/call/client-and-adapters.md — from_call §, re-import §, namespace collision §
- docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md — ADR-017 §3 (from_call flow), §6 (cross-node abort)
- docs/architecture/decisions/022-handler-registration-provenance-and-composition-authority.md — ADR-022 (leaf provenance, None authority/env)
- docs/architecture/decisions/024-operation-registry-layering.md — ADR-024 (Layer 2 overlay)
- docs/architecture/decisions/016-abort-cascade-for-nested-calls.md — ADR-016 §6 (cross-node cascade)
- docs/architecture/decisions/023-operation-error-schemas.md — ADR-023 (error_schemas mirrored)
- docs/research/alknet-call-completion/gap-analysis.md — DC-2, DC-3, DC-5, implementation priority #2
## Notes
> from_call is the client-side consumer of the already-implemented
> services/list + services/schema discovery API. The v1 defaults are
> auto-on-reconnect (DC-2/OQ-27) and error-on-collision (DC-3/OQ-28) — both
> two-way doors, recorded in client-and-adapters.md, revisitable without an
> ADR. The AdapterError type (DC-4/OQ-26) is shared with the
> operation-adapter-trait task — coordinate the enum shape. Cross-node abort
> is transparent via the forwarding handler's parent_request_id (ADR-016 §6).

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---
id: call/client/from-jsonschema
name: Implement from_jsonschema adapter (schema-only registration, FromJsonSchema provenance, no handler)
status: pending
depends_on: [call/client/operation-adapter-trait]
scope: narrow
risk: low
impact: isolated
level: implementation
---
## Description
Implement `from_jsonschema` in `src/client/from_jsonschema.rs`. This is the #4
gap — schema-only registration: produces `HandlerRegistration` bundles with
no handler (`FromJsonSchema` provenance). Used for validation, discovery, and
composition-graph construction without a runtime — type-checking a
composition plan without executing it, building a UI of available operations
without standing up the transports, etc.
### Distinct from from_call (gap analysis DC-5 — confirmed, not a decision)
| | `from_jsonschema` | `from_call` |
|---|---|---|
| Schema source | Provided directly (caller fetches, passes in) | Discovered over wire (`services/list` + `services/schema`) |
| Handler at call time | None (schema-only, `FromJsonSchema` provenance) | Forwards over QUIC (`FromCall` provenance, leaf) |
| Use case | Type validation, discovery, composition graph construction | Actually invoking remote operations |
Keeping them separate preserves the "schema-only, no execution" use case (type
checking, safe composition planning without runtime).
### API
```rust
/// Schema-only registration: produce a HandlerRegistration bundle with
/// FromJsonSchema provenance and no handler. The caller fetches the JSON
/// Schema doc and passes it in; this adapter does no network I/O.
pub fn from_jsonschema(
spec: OperationSpec,
schema: serde_json::Value,
) -> HandlerRegistration;
```
The bundle:
- `provenance: FromJsonSchema`
- `composition_authority: None` (no composition — it's schema-only)
- `scoped_env: None` (leaf-equivalent — no reachability)
- `capabilities: Capabilities::new()` (empty — no outbound credentials, no handler to use them)
- `remote_safe: false` (default — ADR-028 §4; provenance-aware default)
- `handler`: a placeholder that returns a `NOT_FOUND`-style or
`INVALID_INPUT`-style error if ever invoked. Since `FromJsonSchema` ops are
`Internal`/not-remote-safe by default and have no composition authority, they
should never be dispatched; the placeholder makes the type-level constraint
hold (the `Handler` type requires a closure) and fails loudly if a bug routes
a call to it.
### OperationAdapter impl
`from_jsonschema` implements the `OperationAdapter` trait (from
`operation-adapter-trait`). Because it does no I/O, the `import()` body
contains no `.await` points — it trivially satisfies the async trait.
```rust
pub struct FromJsonSchema {
spec: OperationSpec,
schema: serde_json::Value,
}
#[async_trait]
impl OperationAdapter for FromJsonSchema {
async fn import(&self) -> Result<Vec<HandlerRegistration>, AdapterError> {
// No .await — pure parse. Validates schema shape if useful, returns bundle.
Ok(vec![from_jsonschema(self.spec.clone(), self.schema.clone())])
}
}
```
If the schema is malformed, return `AdapterError::SchemaParse`.
### Why this is standalone (medium priority)
`from_jsonschema` doesn't depend on `CallClient` or `from_call` — it's pure
parse with no transport. It's sequenced after `operation-adapter-trait` only
because it implements the trait; if the trait lands first, this can proceed
in parallel with `call-client`/`from-call`. It's medium priority because the
primary consumers (runner, container service, agent) need `from_call`, not
`from_jsonschema`; the schema-only use case is validation/discovery tooling.
## Acceptance Criteria
- [ ] `src/client/from_jsonschema.rs` exists with `from_jsonschema` fn + `FromJsonSchema` struct
- [ ] `from_jsonschema` produces a `HandlerRegistration` with `provenance: FromJsonSchema`
- [ ] `composition_authority: None`, `scoped_env: None`, empty `capabilities`
- [ ] `remote_safe: false` (provenance-aware default, ADR-028 §4)
- [ ] Handler placeholder returns an error if invoked (no real handler)
- [ ] `FromJsonSchema` implements `OperationAdapter` (async, no .await in import)
- [ ] Malformed schema returns `AdapterError::SchemaParse`
- [ ] No network I/O (pure parse — caller fetches the doc)
- [ ] Unit test: from_jsonschema produces a bundle with correct provenance + None fields
- [ ] Unit test: placeholder handler returns error when invoked
- [ ] Unit test: OperationAdapter impl returns Ok with one bundle
- [ ] Unit test: malformed schema returns SchemaParse error
- [ ] `cargo test -p alknet-call` succeeds
- [ ] `cargo clippy -p alknet-call --all-targets` succeeds with no warnings
## References
- docs/architecture/crates/call/client-and-adapters.md — from_jsonschema §, from_jsonschema vs from_call table
- docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md — ADR-017 §5 (FromJsonSchema impl)
- docs/architecture/decisions/022-handler-registration-provenance-and-composition-authority.md — ADR-022 (FromJsonSchema provenance, leaf-equivalent None fields)
- docs/architecture/decisions/028-callclient-peer-scoped-registry-filtering.md — ADR-028 §4 (remote_safe default false)
- tasks/call/client/operation-adapter-trait.md — prerequisite (the trait + AdapterError)
- docs/research/alknet-call-completion/gap-analysis.md — DC-5, implementation priority #4
## Notes
> from_jsonschema is distinct from from_call (DC-5): schema source is
> provided directly (caller fetches), there's no handler at call time, and
> the use case is validation/discovery/composition-graph construction without
> a runtime. It's pure parse with no transport, so it can proceed in parallel
> with call-client/from-call once the trait lands. The placeholder handler
> fails loudly if a bug ever routes a call to a schema-only op — they're
> Internal + not-remote-safe + no composition authority, so dispatch should
> never reach them.

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---
id: call/client/operation-adapter-trait
name: Define OperationAdapter async trait + AdapterError enum (ADR-017 §5, DC-4/OQ-26)
status: pending
depends_on: [call/registry/handler-registration]
scope: narrow
risk: low
impact: project
level: implementation
---
## Description
Define the `OperationAdapter` async trait and the `AdapterError` crate-level
enum in `src/client/adapter.rs` (or `src/registry/adapter.rs` — pick the
module that keeps the trait near the types it produces). This is the #3 gap
(enabling, not blocking) — `from_call` can be built as a free function before
the trait exists, but the trait is needed before `alknet-http`'s
`from_openapi`/`from_mcp` adapters can be built. Small, standalone, unblocks
`alknet-http` Phase 1.
### The trait (ADR-017 §5)
```rust
#[async_trait]
pub trait OperationAdapter: Send + Sync {
async fn import(&self) -> Result<Vec<HandlerRegistration>, AdapterError>;
}
```
The trait is **async** because `from_call` requires async discovery
(`services/list` + `services/schema` over a QUIC connection). Sync adapters
(`from_openapi`, `from_mcp` reading a static spec) trivially satisfy an async
trait — their `import()` bodies contain no `.await` points. This is locked by
ADR-017 §5; the async/sync question is decided.
The return type is `Vec<HandlerRegistration>` (not `(OperationSpec, Handler)`
pairs) — ADR-022 changed the registration API to the bundle shape, and
adapters must produce bundles. Adapter convenience methods construct bundles
with `composition_authority: None` and `scoped_env: None` for the leaf ops they
produce.
The `to_*` adapters (`to_openapi`, `to_mcp`) are outbound projections, not
`OperationAdapter` implementations — they consume the registry, they don't
produce entries for it (ADR-017 §5). Do not implement `to_*` here.
### AdapterError (DC-4, OQ-26)
ADR-017 §5 showed `async fn import(&self) -> Vec<HandlerRegistration>` with no
error type. A real implementation needs to handle failures. The trait returns
`Result<Vec<HandlerRegistration>, AdapterError>` where `AdapterError` is a
crate-level enum covering the failure modes real implementations hit:
- `DiscoveryFailed` — `from_call` remote unreachable / `services/list` failed
- `SchemaParse` — `from_openapi` / `from_jsonschema` couldn't parse the spec
- `Transport` — underlying transport error (QUIC for `from_call`, HTTP for
`from_openapi`/`from_mcp`)
- `Unauthorized` — HTTP 401 for `from_openapi`/`from_mcp`, auth rejected for
`from_call`
- `Conflict` — namespace collision in `from_call` (DC-3); reuse for other
adapter collisions
The exact variant set is the two-way-door remainder (OQ-26); the *presence* of
an error type is recorded in `client-and-adapters.md`. Pick the variants
above as the v1 set; add a `#[non_exhaustive]` so `alknet-http`'s adapters can
extend without breaking match arms. Use `thiserror::Error` for the derive
(consistent with the crate's existing error types).
### Where the trait lives
The trait lives in **alknet-call** (where the types — `HandlerRegistration`,
`OperationSpec`, `Handler` — live). The *implementations* live where their
transport dependencies live (the adapter location map, client-and-adapters.md):
- `FromCall` — QUIC-backed (in `alknet-call`, task `call/client/from_call`)
- `FromJsonSchema` — pure parse, no transport (in `alknet-call`, task
`call/client/from-jsonschema`)
- `FromOpenAPI` — HTTP-backed (in `alknet-http`, separate Phase 0)
- `FromMCP` — MCP streamable-HTTP-backed (in `alknet-http`, feature-gated,
separate Phase 0)
Do not implement `FromOpenAPI`/`FromMCP` here — those are `alknet-http` tasks.
This task defines the trait + error; `from_call` and `from_jsonschema`
implement it (in their tasks).
### Implementations registered in this task
Optionally implement a trivial `FromJsonSchema` adapter in this task if it
falls out naturally (it's a pure-parse adapter with no transport — see
`call/client/from-jsonschema`). If it doesn't fall out naturally, leave it for
the `from-jsonschema` task; the trait + error alone satisfy this task's
acceptance criteria.
## Acceptance Criteria
- [ ] `OperationAdapter` trait defined: `async fn import(&self) -> Result<Vec<HandlerRegistration>, AdapterError>`
- [ ] Trait is `#[async_trait]` (async — ADR-017 §5, locked)
- [ ] `AdapterError` enum defined with `#[non_exhaustive]` and `thiserror::Error`
- [ ] `AdapterError` variants: `DiscoveryFailed`, `SchemaParse`, `Transport`, `Unauthorized`, `Conflict`
- [ ] Trait + error are `pub` and re-exported from `lib.rs`
- [ ] Trait is located in alknet-call (where the types live), not alknet-http
- [ ] Doc comments link to ADR-017 §5 and client-and-adapters.md
- [ ] Unit test: a trivial test adapter implementing the trait compiles and returns Ok
- [ ] Unit test: a test adapter returning `Err(AdapterError::SchemaParse)` compiles
- [ ] `cargo test -p alknet-call` succeeds
- [ ] `cargo clippy -p alknet-call --all-targets` succeeds with no warnings
## References
- docs/architecture/crates/call/client-and-adapters.md — OperationAdapter trait §, Adapter Location Map §
- docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md — ADR-017 §5 (the trait contract), Amendments (DC-4 resolution)
- docs/architecture/open-questions.md — OQ-26 (AdapterError variants, two-way-door remainder)
- docs/research/alknet-call-completion/gap-analysis.md — DC-4, implementation priority #3
## Notes
> The trait is async because from_call needs async discovery; sync adapters
> (from_openapi reading a static spec) trivially satisfy it. The trait lives
> in alknet-call (where the types live); implementations live with their
> transport deps (from_call/from_jsonschema here, from_openapi/from_mcp in
> alknet-http). The AdapterError variants are the two-way-door remainder
> (OQ-26) — `#[non_exhaustive]` lets alknet-http extend without breaking. This
> task is small and standalone; it unblocks alknet-http Phase 1's adapter
> implementations. The to_* adapters are projections, not OperationAdapter
> impls — don't implement them here.

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---
id: call/registry/remote-safe-marking
name: Add remote_safe field to HandlerRegistration for CallClient peer-scoped filtering (ADR-028)
status: pending
depends_on: []
scope: narrow
risk: medium
impact: isolated
level: implementation
---
## Description
Add the `remote_safe: bool` field to `HandlerRegistration` (and its builder) so
that a `CallClient` can default-deny which operations it exposes to a remote
peer. This is the v1 shape of the peer-scoped filtering mechanism locked by
ADR-028. It is the prerequisite for `call/client/call-client` (the
`CallClient`'s dispatch path reads this field) and is the only one-way-door
piece of the call-completion work, so it goes first.
### Field
```rust
pub struct HandlerRegistration {
pub spec: OperationSpec,
pub handler: Handler,
pub provenance: OperationProvenance,
pub composition_authority: Option<CompositionAuthority>, // None for leaves
pub scoped_env: Option<ScopedOperationEnv>, // None for leaves
pub capabilities: Capabilities,
pub remote_safe: bool, // default false; ADR-028 — exposes this op to
// CallClient peers (trusted-peer mode bypasses)
}
```
`remote_safe` defaults to `false` across **all** provenance (Local, Session,
and the leaf provenances — see ADR-028 §4). The operator flips specific
operations to `true` when they want a peer to reach them. This mirrors the
default-deny posture of ADR-015 (visibility `Internal` by default) and
ADR-022 (composition authority `None` for leaves by default).
### Builder
`OperationRegistryBuilder` needs a way to set `remote_safe`:
- `.with_local(...)` / `.with_leaf(...)` / `.with(...)` should default
`remote_safe: false` (current call sites stay valid unchanged).
- Add a chainable setter, e.g. `.remote_safe(true)` on the builder or a
`with_local_remote(...)` / explicit-arg variant. The exact builder API shape
is a two-way door — pick the least invasive (an optional trailing arg or a
builder setter method); do not over-engineer per-peer allowlists (that's
OQ-25's two-way-door remainder, explicitly out of scope here).
### services/list interaction (ADR-028 Assumption 2)
`services/list` already filters by `Visibility::External` (ADR-015). Per
ADR-028 Assumption 2, when served to a `CallClient` peer, `services/list` must
**additionally hide** non-remote-safe ops — a peer should not see ops it
cannot call, so discovery and dispatch filters agree. The
`services_list_handler` in `registry/discovery.rs` currently filters only on
`visibility`.
**Scoping note**: the `services/list` handler doesn't know whether the caller
is a `CallClient` peer or a local process. The v1 implementation: the filter
applied by `services/list` is the *registry's* filter, and the peer-scoped
*view* a `CallClient` exposes is built atop this. The cleanest v1 split is:
- `services/list` keeps filtering by `Visibility::External` (unchanged).
- The `CallClient`'s peer-scoped view (task `call/client/call-client`) is a
dispatch-time read that additionally filters by `remote_safe`, and the
`CallClient`'s *own* `services/list` serving (when it receives
`services/list` from the remote peer) hides non-remote-safe ops.
So this task adds the **field + builder setter + provenance defaults**, and
the *filtering behavior* that consumes the field is wired in
`call/client/call-client` (the dispatch path) and — for the
`services/list`-hides-non-remote-safe behavior — in the `CallClient`'s
serving path. **This task only adds the data and defaults**, plus a unit
test that the field defaults to `false` and that the setter flips it. Keep
this task tightly scoped: adding the field must not change any existing
dispatch behavior (the field is read-only by the CallClient layer added
later).
## Acceptance Criteria
- [ ] `HandlerRegistration` has `pub remote_safe: bool` field
- [ ] All existing `with_local` / `with_leaf` / `with` builder call sites
compile unchanged (default `remote_safe: false`)
- [ ] A builder setter exists to set `remote_safe: true` (e.g.
`.remote_safe(true)` or an explicit-arg variant)
- [ ] Provenance-aware defaults: `Local`, `Session`, `FromOpenAPI`, `FromMCP`,
`FromCall`, `FromJsonSchema` all default to `false` (ADR-028 §4)
- [ ] No existing dispatch path behavior changes (field is data-only here;
the CallClient filter that reads it is a later task)
- [ ] `services/list` handler is unchanged in this task (filtering wired later)
- [ ] Unit test: `HandlerRegistration` default has `remote_safe == false`
- [ ] Unit test: builder setter produces `remote_safe == true`
- [ ] Unit test: all six provenance variants default `remote_safe == false`
- [ ] `cargo test -p alknet-call` succeeds
- [ ] `cargo clippy -p alknet-call --all-targets` succeeds with no warnings
## References
- docs/architecture/decisions/028-callclient-peer-scoped-registry-filtering.md — ADR-028 (the one-way door; §2 field location, §4 provenance defaults, Assumption 2 services/list hide)
- docs/architecture/crates/call/operation-registry.md — HandlerRegistration struct sketch (now shows `remote_safe`)
- docs/architecture/crates/call/client-and-adapters.md — CallClient § (consumes the field; trusted-peer bypass)
- docs/research/alknet-call-completion/gap-analysis.md — DC-1
## Notes
> This is the one-way-door piece of the call-completion work: the *existence*
> of default-deny filtering is locked by ADR-028; this task adds only the v1
> data shape (`remote_safe: bool`) and defaults. The richer per-peer shape
> (allowlist, capability-class tag) is explicitly out of scope — it's the
> two-way-door remainder tracked as OQ-25. Do not implement per-peer logic
> here. The filtering *behavior* (dispatch path + services/list hide) is wired
> in `call/client/call-client`, not here — this task is data + defaults only
> so it can land first and unblock the CallClient task.

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---
id: call/review-completion
name: Review alknet-call client/adapter completion for spec conformance (ADR-017, ADR-028) and no-env-vars invariant
status: pending
depends_on: [call/client/from-call, call/client/operation-adapter-trait, call/client/from-jsonschema]
scope: broad
risk: low
impact: phase
level: review
---
## Description
Review the alknet-call client/adapter completion (the gap ADR-017 left to
implementation, now specced in `client-and-adapters.md`) for spec conformance,
security-constraint conformance, and pattern consistency. This is the quality
checkpoint at the end of the call-completion batch — the work that unblocks
every downstream consumer (runner, container service, bilateral exchange,
NAPI, agent cross-node dispatch).
### Review Checklist
1. **CallClient conformance** (client-and-adapters.md §CallClient):
- `CallClient` struct with registry, identity_provider, trusted_peer
- `new()` constructs default-deny (trusted_peer: false)
- `trusted_peer()` constructs trusted-peer mode (explicit opt-in)
- `connect()` opens QUIC on ALPN `alknet/call`, returns CallConnection
- Dispatch loop is **shared** with CallAdapter (refactored, not duplicated — ADR-017 §1)
- Connection symmetry (ADR-017 §2): both sides call each other after establishment
- Credentials from Capabilities, not env vars (ADR-014, no-env-vars invariant)
2. **Peer-scoped filtering conformance** (ADR-028):
- Default-deny: op with `remote_safe == false` returns NOT_FOUND to remote peer
- Default-deny: `OperationContext.capabilities` populated only for remote-safe ops
- Trusted-peer mode: all External ops dispatch regardless of remote_safe
- services/list hides non-remote-safe ops in default mode (ADR-028 Assumption 2)
- services/list lists all External ops in trusted-peer mode
- Dispatch-time read over single Layer-0 registry (not a copy — ADR-028 §5)
- `remote_safe` defaults false across all provenance (ADR-028 §4)
3. **from_call conformance** (client-and-adapters.md §from_call):
- Calls services/list then services/schema for each op
- Constructs HandlerRegistration with `provenance: FromCall`
- Forwarding handler sends call.requested via CallConnection
- Subscription forwarding yields until completed/aborted
- `composition_authority: None`, `scoped_env: None` (leaf — ADR-022)
- `remote_safe: false` on FromCall leaves
- Namespace collision = error (DC-3/OQ-28), not silent overwrite
- Re-import on connection establishment (DC-2/OQ-27, v1 default)
- Cross-node abort via parent_request_id (ADR-016 §6)
4. **OperationAdapter trait conformance** (client-and-adapters.md §OperationAdapter):
- `async fn import(&self) -> Result<Vec<HandlerRegistration>, AdapterError>`
- Trait is `#[async_trait]` (async — ADR-017 §5, locked)
- `AdapterError` is `#[non_exhaustive]` + `thiserror::Error`
- Variants: DiscoveryFailed, SchemaParse, Transport, Unauthorized, Conflict
- Trait lives in alknet-call (where the types live), not alknet-http
5. **from_jsonschema conformance** (client-and-adapters.md §from_jsonschema):
- `provenance: FromJsonSchema`, no real handler (placeholder errors if invoked)
- `composition_authority: None`, `scoped_env: None`, empty capabilities
- `remote_safe: false` (provenance default, ADR-028 §4)
- Implements OperationAdapter, no .await in import (pure parse)
- Malformed schema → `AdapterError::SchemaParse`
6. **Adapter location map conformance** (client-and-adapters.md §Adapter Location Map):
- OperationAdapter trait + from_call + from_jsonschema + CallClient in alknet-call
- No HTTP client / HTTP server deps in alknet-call (stays lean)
- from_openapi/from_mcp/to_openapi/to_mcp NOT in alknet-call (deferred to alknet-http)
- MCP stdio not built (security position, not a feature gap)
7. **No-env-vars invariant** (client-and-adapters.md §No-Env-Vars Invariant):
- Credential path: vault → assembly → Capabilities → HandlerRegistration.capabilities → OperationContext.capabilities → handler
- No handler reads outbound credentials from any source other than OperationContext.capabilities
- No `std::env::var` reads in the credential path
- The invariant is enforced by the dispatch path (build_root_context), not runtime convention
8. **ADR conformance (completion-specific)**:
- ADR-017 §1: shared dispatch loop, CallClient own registry (now peer-scoped per ADR-028)
- ADR-017 §2: connection direction independent of call direction
- ADR-017 §3: from_call flow (services/list + services/schema), FromCallConfig prefix/filter
- ADR-017 §5: async trait, bundles not (spec,handler) pairs, to_* are projections not impls
- ADR-017 §6: cross-node abort cascade through from_call handler
- ADR-017 §7: credentials from capabilities (TLS identity, auth token, remote identity)
- ADR-028: default-deny, remote_safe bool, trusted-peer opt-in, dispatch-time read, services/list hide
9. **Security constraints (completion-specific)**:
- Default-deny filtering: remote peer can't trigger capability exposure for non-remote-safe ops
- Trusted-peer opt-in is explicit, never default
- Capabilities non-serializable, never cross the wire (ADR-014)
- from_call trust is transitive (remote node's code runs) — recorded in spec, not enforced beyond scoped env
- FromCall/FromJsonSchema leaves have no composition authority (can't escalate)
10. **Test coverage**:
- Integration test: two-node call (CallClient ↔ CallAdapter, both call each other)
- Integration test: default-deny op → NOT_FOUND to remote peer
- Integration test: remote_safe op dispatches to remote peer
- Integration test: trusted-peer mode exposes all External ops
- Integration test: services/list hides non-remote-safe in default mode
- Integration test: from_call populates Layer 2 overlay, forwarding works
- Integration test: subscription forwarding streams remote events
- Integration test: namespace collision returns error
- Integration test: cross-node abort cascades through from_call handler
- Unit tests: AdapterError variants, OperationAdapter trait compiles
11. **Spec drift check**: verify `client-and-adapters.md` still matches the
implementation after the completion (no spec/impl drift introduced during
implementation). In particular: the CallClient struct sketch, the
CallCredentials sketch, the FromCallConfig fields, the AdapterError
variants, and the remote_safe field on HandlerRegistration.
## Acceptance Criteria
- [ ] CallClient matches client-and-adapters.md (struct, new/trusted_peer, connect, shared loop)
- [ ] Peer-scoped filtering matches ADR-028 (default-deny, trusted-peer, services/list hide)
- [ ] from_call matches client-and-adapters.md (flow, FromCallConfig, provenance, None fields)
- [ ] OperationAdapter trait + AdapterError match client-and-adapters.md (async, non_exhaustive, variants)
- [ ] from_jsonschema matches client-and-adapters.md (provenance, placeholder handler, no I/O)
- [ ] Adapter location map respected (no HTTP deps in alknet-call; from_openapi/mcp not built here)
- [ ] No-env-vars invariant holds (credentials from Capabilities, no env-var reads)
- [ ] ADRs 017 + 028 conformed to (plus 014/015/016/022/023/024 where touched)
- [ ] Default-deny security constraint enforced (no capability exposure for non-remote-safe)
- [ ] Integration tests cover two-node call, default-deny, trusted-peer, from_call, abort cascade
- [ ] No spec/impl drift in client-and-adapters.md (or drift documented + spec amended)
- [ ] `cargo fmt --check -p alknet-call` passes
- [ ] `cargo clippy -p alknet-call --all-targets` passes with no warnings
- [ ] All tests pass
## References
- docs/architecture/crates/call/client-and-adapters.md — the spec being reviewed against
- docs/architecture/crates/call/README.md — crate index (now lists client-and-adapters.md)
- docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md — ADR-017 (amended)
- docs/architecture/decisions/028-callclient-peer-scoped-registry-filtering.md — ADR-028
- docs/architecture/open-questions.md — OQ-25..28 (two-way-door remainders — verify defaults match spec)
- docs/research/alknet-call-completion/gap-analysis.md — DC-1..4, the decisions this batch resolved
- tasks/call/registry/remote-safe-marking.md
- tasks/call/client/call-client.md
- tasks/call/client/from-call.md
- tasks/call/client/operation-adapter-trait.md
- tasks/call/client/from-jsonschema.md
## Notes
> This review closes the call-completion batch. The load-bearing security
> invariant is ADR-028's default-deny: a remote peer's call must not trigger
> dispatch that populates OperationContext.capabilities from the local
> registration bundle unless the op is explicitly remote-safe. Verify this
> with a test that asserts a non-remote-safe op's call does NOT populate
> capabilities (not just that it returns NOT_FOUND — the security argument is
> about capability exposure, not just call denial). The no-env-vars invariant
> (ADR-014) is the dispatch-side corollary: no handler reads credentials from
> any source other than OperationContext.capabilities. The shared dispatch
> loop (ADR-017 §1) is the architectural commitment that keeps CallClient from
> becoming a parallel protocol implementation — verify the loop is genuinely
> shared (refactored out of CallAdapter), not copy-pasted. If deviations are
> found, document and fix before considering the call-completion batch done.
> This unblocks every downstream consumer, so spec/impl drift here propagates.