# ADR-083: Endpoint as Multi-Transport Accept-Loop Runner with Public Dispatch ## Status Accepted (revised 2026-07-14: TCP+TLS moved inside the endpoint as a third owned transport, not an external loop. This dissolves the multi-owner shutdown problem — the endpoint owns all its accept loops. `dispatch` stays public for genuinely external shapes: SSH channels, WebTransport streams. See §"TCP+TLS is a first-class owned transport". All TLS-scope OQs resolved; advanced to Accepted ahead of the task-decomposition session.) Accepted (amended 2026-07-15: the endpoint is extracted from `alknet-core` into a new crate `alknet-endpoint`. The ADR's shape (`new` + builder methods + public `dispatch` + `run` / `shutdown`) is unchanged; the *location* changes. See §"Amendment 2026-07-15 — crate extraction".) ## Context `AlknetEndpoint` (ADR-010) conflates two concerns: 1. **Transport construction** — building `quinn::Endpoint` and `iroh::Endpoint`, reading `static_config.tls_identity`, constructing TLS internally (`TlsSetup::new`, `build_rustls_server_config`), wrapping rustls into `quinn::ServerConfig`, binding. 2. **Dispatch** — take a connection, extract its ALPN, look up the handler, build `AuthContext`, spawn the handler. The conflation was tolerable while TLS was welded to quinn (one transport, one cert path). Two things surfaced it: - **ADR-082 (`alknet-tls` extraction)** pulls quinn's TLS construction out of the endpoint into a shareable `TlsServerConfig`. Once the cert is built outside the endpoint, the endpoint's transport-construction role is the odd one out — it's the only thing still reading `static_config` and building transports. - **A hub holds two `TlsServerConfig`s**, not one (raw key for native clients on QUIC + TCP+TLS fallback; X.509/ACME for HTTPS on TCP+TLS). ADR-082's original signature `AlknetEndpoint::new(..., Arc)` cannot represent this — a hub has two configs and the endpoint has no single "the TLS config" to take. The TLS extraction surfaces this because the endpoint can no longer build the one cert it used to own. ### The dispatch logic is the endpoint's real value Stripped of transport construction, what the endpoint provides is **dispatch**: take a connection, extract its ALPN, look up the handler, build `AuthContext`, spawn. This is identical for every transport. The transport-specific parts are narrow bookends: - **ALPN extraction** — quinn: `handshake_data().protocol`; iroh: `connecting.alpn().await`; TCP+TLS: `tls_stream.alpn()`. - **Fingerprint extraction** — quinn: `peer_identity()` → `CertificateDer`; iroh: `remote_id()` → `ed25519:`; TCP+TLS: `tls_stream.peer_certificates()` → `CertificateDer`. - **Connection construction** — quinn: `from_quinn_with_alpn`; iroh: `from_iroh`; TCP+TLS: `from_bidi(tls_stream, alpn, remote_addr)`. - **No-handler close** — quinn/iroh: `connection.close()`; TCP+TLS: drop the stream (the `Connection::close` API handles both uniformly — ADR-065). Everything between those bookends — the ACME ALPN guard, the handler lookup, the `build_auth_context` call, the `tokio::spawn` — is identical. ### TCP+TLS is a first-class owned transport TCP+TLS is the most common transport after raw-key QUIC, not an edge case: HTTPS for browsers, worker registration over HTTP, raw-key fallback for native clients when UDP is blocked. A hub — and any hub-worker — needs it. ADR-010 Amendment 1 made TCP+TLS a "sibling accept loop" outside the endpoint because the endpoint's dispatch logic was crate-private and couldn't be shared. The reason TCP+TLS was *structurally* excluded — the endpoint built transports internally, and TCP+TLS couldn't fit that shape — is gone after this ADR: the endpoint no longer builds transports. It runs accept loops on whatever it's given. TCP+TLS is a listener transport, same shape as quinn and iroh: | Transport | What `with_*` takes | Accept loop | |-----------|---------------------|-------------| | quinn | `quinn::Endpoint` | `quinn.accept()` → handshake → `Connection::from_quinn_with_alpn` | | iroh | `iroh::Endpoint` | `iroh.accept()` → alpn+handshake → `Connection::from_iroh` | | TCP+TLS | `TcpListener` + `TlsAcceptor` | `tcp.accept()` → `tls.accept()` → `Connection::from_bidi` | All three are: accept → extract ALPN + fingerprint → construct `Connection` → dispatch. The endpoint already runs the first two; the third is the same pattern with a different accept call. Making TCP+TLS an owned transport (via `with_tcp_tls(listener, acceptor)`) instead of an external loop gives the endpoint a single, uniform ownership model: it owns all its accept loops, `shutdown()` stops them all. No coordination between the endpoint and external loops. This dissolves the multi-owner shutdown problem (the endpoint owns all loops; one owner, one shutdown). The `dispatch` method stays public — but for genuinely external shapes that the endpoint can't own: SSH channels (one connection, many channels with different ALPNs — a multiplexing shape, not a listener shape) and future WebTransport streams (one QUIC connection, many WT streams). These are not listener transports; they're connection-internal multiplexing. The endpoint can't own them the way it owns a `TcpListener`. ### The `acme-tls/1` guard ADR-027 §5 places the `acme-tls/1` early-return guard in `dispatch_quinn`. The rationale (no handler for `acme-tls/1`; the challenge is answered at the TLS layer; close gracefully) is correct. The **location** is wrong once TCP+TLS exists. ACME TLS-ALPN-01 (RFC 8737) challenges are validated by the CA connecting **over TCP to port 443**. Let's Encrypt's validator is a TCP TLS client — it does not speak QUIC. In any real hub deployment, the ACME challenge arrives on the **TCP+TLS** listener (443), not the QUIC listener (4433). Today the guard fires only because quinn happens to be the listener that's bound to the ACME port — an artifact of TCP+TLS not existing yet, not a property of QUIC. The guard's job is transport-agnostic: "if the TLS handshake negotiated `acme-tls/1`, this is a challenge connection — the cert was already served at the TLS layer via `ResolvesServerCertAcme`, close it, no handler." `Connection::close` is transport-abstracted (ADR-065), so the guard works uniformly for quinn, iroh, and TCP+TLS. The right home is the **shared `dispatch` method**, not `dispatch_quinn`. In practice only the TCP+TLS listener on 443 receives challenges (CAs validate via TCP); advertising `acme-tls/1` on a QUIC listener that shares the ACME config is harmless — no QUIC client negotiates it. ### `StaticConfig`'s role shifts `StaticConfig` today holds `listen_addr`, `tls_identity`, `iroh_relay`, `drain_timeout`. After this ADR, the endpoint reads only `drain_timeout` (passed directly to `new`); the assembly layer reads the rest to build transports. `StaticConfig` becomes the canonical deployment config the **assembly layer** reads, not "the thing the endpoint takes." It stays in `alknet-core` (it's a config type) and stays extensible (future transport config fields land here as the assembly layer needs them). The "assembly layer" is, in practice, the deployment binary — today, that's primarily the hub. A pure worker (no inbound endpoints) has a trivial assembly layer; a hub-worker combines both. Putting hub-specific composition in the hub crate is appropriate; putting transport loops that any node might need in the hub crate is not. The TCP+TLS loop belongs in `alknet-endpoint` (behind a `tcp` feature), where any node that wants it can enable the feature and call `with_tcp_tls` — no hub dependency. ## Decision ### The endpoint is a multi-transport accept-loop runner + a public dispatch method ```rust pub struct AlknetEndpoint { quinn: Option, iroh: Option, #[cfg(feature = "tcp")] tcp_tls: Option, // (TcpListener, TlsAcceptor) handlers: Arc, // ADR-010 dynamic: Arc>, // ADR-010, unchanged identity_provider: Arc, // ADR-010, unchanged shutdown_tx: watch::Sender, shutdown_rx: watch::Receiver, drain_timeout: Duration, } impl AlknetEndpoint { pub fn new( handlers: HandlerRegistry, dynamic: Arc>, identity_provider: Arc, drain_timeout: Duration, ) -> Self; pub fn with_quinn(mut self, endpoint: quinn::Endpoint) -> Self; pub fn with_iroh(mut self, endpoint: iroh::Endpoint) -> Self; /// Take ownership of a TCP+TLS listener. The endpoint runs the /// accept loop (`tcp.accept()` → `tls.accept()` → extract ALPN + /// fingerprint → `Connection::from_bidi` → `dispatch`). Feature-gated /// on `tcp` (pulls `tokio-rustls`). A hub serving HTTPS and a /// hub-worker serving TCP+TLS both use this; a pure worker doesn't. #[cfg(feature = "tcp")] pub fn with_tcp_tls( mut self, listener: tokio::net::TcpListener, acceptor: tokio_rustls::TlsAcceptor, ) -> Self; /// Clone of the shutdown watch sender. The assembly layer uses this /// to signal any external dispatch callers (SSH, future WT) to stop. /// The endpoint's own loops (quinn, iroh, TCP+TLS) are signaled /// internally by `shutdown()`. pub fn shutdown_sender(&self) -> watch::Sender; /// Dispatch a pre-established connection by ALPN. Called by the /// endpoint's own accept loops (quinn, iroh, TCP+TLS) after /// transport-specific extraction, and by external dispatch callers /// (SSH channels, future WebTransport streams) after their own /// extraction. /// /// Synchronous (non-async): performs the ACME guard, handler /// lookup, `build_auth_context`, and `tokio::spawn`s the handler. /// Returns immediately after spawning — the handler runs on its own /// task. The caller's accept loop is not blocked by handler /// execution. /// /// No-handler match (ALPN not in the registry): closes the /// connection and logs a warning, per ADR-010's existing dispatch /// behavior. Does not panic, does not return an error — the /// connection is dropped, the accept loop continues. pub fn dispatch( &self, connection: Connection, alpn: Vec, fingerprint: Option, remote_addr: Option, ); /// Run the endpoint's owned accept loops (quinn, iroh, TCP+TLS — /// whichever were configured). Returns when shutdown is signaled. /// The caller drives shutdown via `shutdown()` or `shutdown_sender()`. pub async fn run(self: Arc); /// Signal all owned accept loops to stop, drain in-flight handlers /// for `drain_timeout`, then close. Infallible — the endpoint owns /// all its accept loops (quinn, iroh, TCP+TLS) and takes pre-built /// pre-bound transports, so there is no bind failure path and no /// external loop coordination. No-handler matches are swallowed by /// `dispatch` (close + log). One owner, one shutdown. pub async fn shutdown(&self); } ``` The consumer pattern: the assembly layer (the deployment binary — today primarily the hub) holds `Arc`, clones the `Arc` for `run` (which consumes one clone), and — for external dispatch callers like SSH — passes `&endpoint` to them so they can call `dispatch`. After `run` returns (on shutdown), in-flight dispatched handlers drain per `shutdown()`. `AlknetEndpoint::new` takes **no `StaticConfig`** and **no TLS config**. The assembly layer (the deployment binary that composes crates — see ADR-014) reads `StaticConfig`, builds the transports, and hands the quinn/iroh/TCP+TLS endpoints to `AlknetEndpoint` via builder methods. The `handlers`, `dynamic`, and `identity_provider` fields are unchanged passthroughs from ADR-010 — this ADR does not change auth or dynamic config; it changes who builds transports and where dispatch lives. ### TCP+TLS is owned, not external The TCP+TLS accept loop runs inside `run()` alongside the quinn and iroh loops. It is not an external sibling. This means: - **Shutdown is single-owner.** `endpoint.shutdown()` stops all owned loops (quinn, iroh, TCP+TLS) and drains all dispatched handlers. No coordination between the endpoint and external accept loops. The multi-owner shutdown problem (formerly OQ-61) does not arise. - **Any node can use TCP+TLS.** A hub, a hub-worker, or any node that accepts inbound TCP+TLS enables the `tcp` feature and calls `with_tcp_tls(listener, acceptor)`. No hub dependency. The loop isn't duplicated per binary. - **The TCP+TLS loop's home is `alknet-endpoint`** (behind a `tcp` feature), not the hub crate or the assembly layer. The endpoint crate has `quinn` and `iroh` as feature-gated transport deps; adding `tcp` (pulling `tokio-rustls`) is the same pattern. A deployment that doesn't use TCP+TLS doesn't enable the feature. ### `dispatch` is public — for genuinely external shapes The public `dispatch` method takes the already-extracted ALPN, fingerprint (if available), remote address (if available), and a `Connection`. It performs the ACME guard, the handler lookup, the `build_auth_context` call, and the `tokio::spawn`. `build_auth_context` becomes a private helper called by `dispatch`, not a standalone function — external callers call `dispatch`, which calls `build_auth_context` internally. `dispatch` is for transports the endpoint **can't own** — shapes that aren't listener-based: - **SSH channels** (ADR-065): one SSH connection carries multiple channels with different ALPNs. The SSH handler accepts one connection, then dispatches each channel via `dispatch` with the channel's ALPN. This is connection-internal multiplexing, not a listener loop. - **Future WebTransport streams** (parked per ADR-044): one QUIC connection, many WT streams. Same multiplexing shape. TCP+TLS is **not** an external dispatch caller — it's a listener transport the endpoint owns. The distinction: listener transports (quinn, iroh, TCP+TLS) produce connections from an accept loop the endpoint runs; multiplexing transports (SSH, WT) produce connections from within an existing connection, and the endpoint can't own their accept loop. Transport-specific extraction (`extract_quinn_alpn`, `extract_quinn_client_fingerprint`, `extract_iroh_client_fingerprint`, `extract_tcp_tls_alpn`, `extract_tcp_tls_client_fingerprint`) stays private in the endpoint — the accept loops call them, then call `dispatch` with the results. ### The `acme-tls/1` guard moves to `dispatch` ```rust pub fn dispatch(&self, connection: Connection, alpn: Vec, ...) { if alpn == b"acme-tls/1" { debug!("acme-tls/1 challenge connection completed at TLS layer; closing"); connection.close(0, "acme done"); return; } // ... handler lookup, build_auth_context, spawn } ``` The guard is **not** feature-gated on `acme`: if the `acme` feature is off, no transport advertises `acme-tls/1`, the ALPN never negotiates, the guard never fires. It is harmless dead code without the feature. This supersedes ADR-027 §5's "in `dispatch_quinn`" location. The rationale (no handler for `acme-tls/1`, silent close) holds; only the location changes. The `acme-tls/1` ALPN append still happens in `TlsServerConfig::new`'s ACME branch (ADR-082), not per-transport — every transport using the ACME `TlsServerConfig` advertises it, but in practice only the TCP+TLS listener on 443 receives challenges. ### Feature gates ```toml [features] quinn = ["dep:quinn"] # with_quinn — quinn accept loop iroh = ["dep:iroh"] # with_iroh — iroh accept loop tcp = ["dep:tokio-rustls"] # with_tcp_tls — TCP+TLS accept loop acme = ["dep:rustls-acme"] # (used by alknet-tls, not core directly) ``` The `tcp` feature pulls `tokio-rustls`. A deployment enables the features for the transports it runs. A pure-QUIC node enables `quinn` + `iroh`; a hub serving HTTPS enables `quinn` + `tcp`; a hub-worker enables all three. This matches the existing pattern (`quinn` and `iroh` are already feature-gated transport deps on `alknet-endpoint`). ### `StaticConfig` stays in core; the endpoint drops it `StaticConfig` remains in `alknet-core/config.rs` as the canonical deployment config the assembly layer reads. The endpoint no longer takes `&StaticConfig` — `new()` takes `drain_timeout: Duration` directly. Future transport config fields (addresses, relay URLs, identity) land in `StaticConfig` as the assembly layer needs them; the endpoint's `new` signature does not change when they're added, because the endpoint doesn't read them. ### Transport construction: inlined by the assembly layer The builder functions are trivial API calls. The assembly layer (the deployment binary — today primarily the hub crate's composition code) inlines them: - `build_quinn_endpoint`: `tls_config.for_quinn()` → `quinn::Endpoint::server(addr)` — 2 lines - `build_iroh_endpoint`: iroh builder + key + relay + alpns + bind — 15 lines - `build_tcp_tls`: `TcpListener::bind(addr)` + `tls_config.for_tcp_tls()` — 2 lines These are pure configuration, not shared logic. No helper crate or module — 20 lines total across all three, each binary picks which transports it wants. If a future binary duplicates the iroh builder and the pattern drifts, extraction is a two-way door on the function; the *loop* (the runtime with shutdown + dispatch) is in core, so the duplication risk is only on the trivial builder, not the real component. Hub-specific composition (wiring `ChannelsAdapter`, `HttpAdapter`, `CallAdapter`, the relay, peer lifecycle, worker registration) lives in the hub crate. That's where multi-transport *composition* happens. The endpoint provides the accept loops; the hub provides the handlers and wiring. A `alknet-transport` crate was considered and rejected — it would contain only trivial builder functions (the real component, the TCP+TLS loop, is in core). A crate for 20 lines of API calls doesn't earn its existence. If hub-specific transport helpers accumulate, they live in the hub crate, not a generic transport crate. ### What moves out of `alknet-core/endpoint.rs` | Code | Destination | |------|-------------| | `build_rustls_server_config()` | `alknet-tls` (ADR-082) | | `TlsSetup` / ACME state machine | `alknet-tls` (ADR-082) | | `RawKeyCertResolver` | `alknet-tls` (ADR-082) | | `Ed25519SigningKey` | `alknet-tls` (ADR-082) | | `AcceptAnyCertVerifier` | `alknet-tls` (ADR-082) | | `SelfSignedCert` / `generate_self_signed_cert()` | `alknet-tls` (ADR-082) | | `load_cert_chain()` / `load_private_key()` | `alknet-tls` (ADR-082) | | `build_quinn_server_config_from_rustls()` | `alknet-tls` (`for_quinn()`, ADR-082) | | `build_iroh_endpoint()` | Assembly layer (inlined; 15 lines of iroh API calls) | | `AlknetEndpoint`, `HandlerRegistry`, all dispatch/loop/extraction code | `alknet-endpoint` (this ADR, §"Amendment 2026-07-15") | | `EndpointError` | **removed** — `BindFailed` and `HandlerNotFound` are both vestigial (endpoint takes pre-bound transports; `dispatch` swallows no-handler matches); `shutdown()` is infallible | ### What stays in `alknet-endpoint` (the new crate) - `AlknetEndpoint` struct (multi-transport accept-loop runner + public `dispatch`) - `HandlerRegistry` - `TcpTlsListener` (the `(TcpListener, TlsAcceptor)` tuple for the TCP+TLS field) - `dispatch` (public — ACME guard, handler lookup, `build_auth_context`, spawn) - `dispatch_quinn` / `dispatch_iroh` / `dispatch_tcp_tls` (private — transport-specific extraction, then call `dispatch`) - `run_quinn_accept_loop` / `run_iroh_accept_loop` / `run_tcp_tls_accept_loop` - `extract_quinn_alpn` / `extract_quinn_client_fingerprint` / `extract_iroh_client_fingerprint` / `extract_tcp_tls_alpn` / `extract_tcp_tls_client_fingerprint` - `build_auth_context` (private helper, called by `dispatch`) ### ADR-082 amendment ADR-082's `AlknetEndpoint::new(..., Arc, ...)` signature is superseded by this ADR. The endpoint takes no TLS config; the assembly layer builds transports from `TlsServerConfig`s and hands them to the endpoint via `with_quinn` / `with_iroh` / `with_tcp_tls`. ADR-082 should reference this ADR for the endpoint signature and focus on what `alknet-tls` provides (`TlsServerConfig` and its accessors). ### Amendment 2026-07-15 — crate extraction (`alknet-endpoint`) The endpoint is extracted from `alknet-core` into a new crate `alknet-endpoint`. The ADR's shape — `new(handlers, dynamic, identity_provider, drain_timeout)` + `with_quinn` / `with_iroh` / `with_tcp_tls` + public `dispatch` + `run` / `shutdown` — is **unchanged** by this amendment. Only the *location* changes: `endpoint.rs`, `HandlerRegistry` move from `alknet-core` to `alknet-endpoint` (`EndpointError` is removed — see above). #### Why extract (the dependency data) `alknet-core` is currently two things welded together with different audiences: | Concern | Modules | Depended on by | |---------|---------|----------------| | **Shared types + auth + config** | `types.rs`, `auth.rs`, `config.rs`, `fingerprint.rs`, `ownership.rs`, `store.rs` | every handler crate (call, http, tty, tty-local) — 124 import sites | | **Endpoint (accept-loop runner)** | `endpoint.rs` (1606 LOC) | **zero handler crates** — only the assembly layer (hub/worker) | The handler crates import `alknet_core::types` (57×), `alknet_core::auth` (41×), `alknet_core::config` (13×), `alknet_core::ownership` (7×), `alknet_core::fingerprint` (6×). They import `alknet_core::endpoint` **zero times**. `endpoint.rs` is a one-way leaf consumer of the shared types (it imports `auth`, `config`, `types`; nothing in core imports *from* it). This is the textbook shape for an extraction: a leaf consumer depended on by a different audience than the shared types. #### The dependency-weight win `alknet-core`'s `Cargo.toml` currently carries `quinn`, `iroh`, `rustls-pemfile`, `rcgen`, `rustls-acme`, `rustls` — heavy transport/TLS deps — because `endpoint.rs` uses them. Every handler crate transitively pulls these via `alknet-core`, even though none of them use the endpoint. `alknet-tty` is a pure wire-format handler — it has no business linking quinn. After extraction: - **`alknet-core`** loses `quinn`, `iroh`, `rcgen`, `rustls-pemfile`, `rustls-acme` from its `[dependencies]` (the TLS-setup deps already move to `alknet-tls` per ADR-082; the transport deps move with the endpoint). It keeps `rustls`/`rustls-pki-types` (narrow — for `fingerprint.rs` types, per OQ-59), `ed25519-dalek`, `sha2`, `tokio`, `serde`, `arc-swap`. It becomes a **lightweight types+auth+config crate** — what the handler crates actually want. - **`alknet-endpoint`** gains `quinn`, `iroh` (the accept-loop transports). It depends on `alknet-core` for `Connection`, `ProtocolHandler`, `AuthContext`, `IdentityProvider`, `DynamicConfig`. It does **not** depend on `alknet-tls` — the endpoint takes pre-built transports (per this ADR), so TLS config construction stays in `alknet-tls` at the assembly layer. A handler crate (call, http, tty) no longer transitively links quinn, iroh, rcgen, or rustls-acme. A pure worker (client-only, no inbound) depends on `alknet-client` + handler crates + `alknet-core` and does **not** pull `alknet-endpoint` at all. #### The `quinn` feature split `alknet-core`'s `quinn` feature currently gates two unrelated things: (1) `endpoint.rs`'s quinn accept loop and (2) `types.rs`'s `Connection::from_quinn` / `QuinnBidiStreamSource` constructor. After extraction: - **`Connection::from_quinn` stays in `alknet-core`** (in `types.rs`). It's a shared-type constructor used by both the endpoint's accept loop (server) and `alknet-client`'s `dial_quic` (client, ADR-089) and `CallClient` tests. The `quinn` feature on `alknet-core` gates this constructor — "does `Connection` support quinn-constructed connections" — not "does core run a quinn accept loop." Same for `from_iroh` and the `iroh` feature. - **The quinn accept loop moves to `alknet-endpoint`**, which has its own `quinn` feature for the accept loop. The heavy quinn accept-loop code is in `alknet-endpoint`, not core. #### Symmetry with `alknet-client` (ADR-089) The extraction mirrors the client-side extraction (ADR-089): | Server side | Client side | Audience | |-------------|-------------|----------| | `alknet-endpoint` (this ADR) | `alknet-client` (ADR-089) | the assembly layer (hub, worker, hub-worker) | | `alknet-core` (shared types) | `alknet-core` (shared types) | every handler crate | A **hub** depends on `alknet-endpoint` + `alknet-client` + handler crates + `alknet-core` (transitively). A **pure worker** depends on `alknet-client` + handler crates + `alknet-core` — no `alknet-endpoint`. A **handler crate** depends on `alknet-core` only — neither endpoint nor client. #### Implementation: build new, delete old The endpoint's `endpoint.rs` is 1606 lines of `#[cfg(feature = "quinn")]` / `#[cfg(feature = "iroh")]` / `#[cfg(feature = "acme")]` conditionals — the TLS-setup code that ADR-082 moves to `alknet-tls`, the `StaticConfig`-taking constructor that this ADR replaces, the `acme-tls/1` guard that this ADR moves to shared `dispatch`. Building `alknet-endpoint` fresh against this ADR's shape — `new()` + builder methods + public `dispatch` + `run` / `shutdown`, importing `Connection`/`ProtocolHandler`/`AuthContext` from `alknet-core`, no TLS setup (that's `alknet-tls`'s job now) — is cleaner than editing the 1606-line conditional file in place. The old `endpoint.rs` becomes a deletion, not a refactor. This is pruning (cutting the endpoint + the TLS deps that already move to `alknet-tls`), not a massive inline refactor. #### What `alknet-core` looks like after `alknet-core` after the extraction + the ADR-082 TLS pruning: | Module | LOC | Stays? | |--------|-----|--------| | `types.rs` (`Connection`, `ProtocolHandler`, `BiStream`, `BidiStreamSource`, `StreamError`, `Capabilities`) | ~1100 | yes — shared by every crate | | `auth.rs` (`AuthContext`, `Identity`, `IdentityProvider`, `IdentityStore`, `AuthToken`) | ~640 | yes — shared by every crate | | `config.rs` (`StaticConfig`, `DynamicConfig`, `TlsIdentity`, `Ed25519SecretKey`) | ~710 | yes — shared config types | | `fingerprint.rs` | ~260 | yes — shared by server + client (OQ-59) | | `ownership.rs` (`OwnershipStore`, `OwnershipProvider`) | ~280 | yes — shared | | `store.rs` (`CredentialStore`, `EncryptedData`) | ~200 | yes — shared | | `endpoint.rs` (`AlknetEndpoint`, `HandlerRegistry`) | ~1600 | **no** — moves to `alknet-endpoint` (`EndpointError` is removed, not moved) | Core loses ~1600 LOC (the endpoint) and 5 heavy deps (`quinn`, `iroh`, `rcgen`, `rustls-pemfile`, `rustls-acme`). The remaining ~3200 LOC is the lightweight types+auth+config+ownership+store+fingerprint surface that every handler crate depends on. ## Consequences **Positive:** - The endpoint has one job: run accept loops + dispatch. Transport construction lives outside it, where the multi-`TlsServerConfig` hub case is natural. - TCP+TLS is a first-class owned transport — same `run()` loop, same `shutdown()`, same dispatch path as quinn/iroh. No duplicated `build_auth_context` or handler-lookup logic anywhere. ADR-010 Amendment 1's sibling-dispatch workaround is retired entirely. - Shutdown is single-owner. The endpoint owns all its loops; one `shutdown()` stops them all and drains. The multi-owner shutdown problem (formerly OQ-61) does not arise. - Any node can use TCP+TLS — enable the `tcp` feature, call `with_tcp_tls`. No hub dependency. A hub-worker serving TCP+TLS is the same code path as a hub serving TCP+TLS. - The `acme-tls/1` guard is transport-agnostic — it works for TCP+TLS (where challenges actually arrive) and any future transport. ADR-027 §5's quinn-specific location is corrected. - `StaticConfig`'s role is clear: it's the assembly-layer config, not the endpoint's. Adding transport config fields doesn't churn the endpoint's `new` signature. - The hub (the first multi-transport consumer) is unblocked: build two `TlsServerConfig`s, build quinn/iroh/TCP+TLS listeners, hand all three to the endpoint, `run()`. - `dispatch` stays public for genuinely external shapes (SSH channels, future WT streams) — transports the endpoint can't own because they're connection-internal multiplexing, not listener-based. - **The endpoint is extracted into `alknet-endpoint`** (Amendment 2026-07-15). Handler crates no longer transitively link quinn, iroh, rcgen, or rustls-acme. A pure worker (client-only) does not pull the endpoint at all. The dep graph is symmetric with `alknet-client` (ADR-089): `alknet-core` is the shared types crate; `alknet-endpoint` and `alknet-client` are the server-side and client-side establishment crates that depend on it. **Negative:** - `AlknetEndpoint::new` signature changes (breaking). Pre-1.0, in-repo consumers only — the assembly layer and tests must update. Expected; this is the point of the refactor. - `alknet-endpoint` gains a `tcp` feature (pulls `tokio-rustls`). This is the same pattern as the `quinn` and `iroh` features — a transport that the endpoint can own. A deployment that doesn't use TCP+TLS doesn't enable it. `alknet-core` keeps a narrow `rustls` dep (for `fingerprint.rs` types, per OQ-59); `tokio-rustls` is the acceptor wrapper over `rustls::ServerConfig`, not a separate TLS stack, and lives in `alknet-endpoint`, not core. - `build_iroh_endpoint` leaves core (inlined by the assembly layer). This is a one-way dep-graph change: the binary that uses iroh depends on `iroh` directly, not via `alknet-core` or `alknet-endpoint`. This is correct — the binary *is* the thing that knows which transports it wants. The 15 lines are pure iroh API calls; no shared logic is lost. - This ADR revises ADR-010's "TCP is not an endpoint struct concern" more deeply than the original ADR-083 draft. The reason TCP was excluded (the endpoint built transports internally, TCP+TLS couldn't fit) is gone; the endpoint is now a multi-transport accept-loop runner and TCP+TLS is a listener transport that fits the same shape. ## Door type **One-way.** The endpoint's `new` signature, the public `dispatch` contract, the "endpoint owns dispatch, not construction" boundary, the "endpoint owns TCP+TLS as a first-class transport" decision, and the extraction of the endpoint into `alknet-endpoint` (a separate crate from `alknet-core`) are structural. Reversing would mean re-welding transport construction to the endpoint, re-privatizing `dispatch`, pushing TCP+TLS back outside, and re-merging the endpoint into core — breaking every multi-transport consumer (hub, hub-worker, future SSH, future WT) and re-coupling every handler crate to quinn/iroh/rcgen. The `dispatch` signature (`connection, alpn, fingerprint, remote_addr`) is one-way — changing it after consumers exist is a rewrite. The internal implementation (how extraction is factored, how `run` spawns tasks, the TCP+TLS loop's internal structure) is two-way. ## References - ADR-010: ALPN router and endpoint (amended — the endpoint no longer constructs transports; "TCP is not an endpoint struct concern" is revised: TCP+TLS is now a first-class owned transport via `with_tcp_tls`; Amendment 1's sibling-dispatch workaround is retired by the public `dispatch` method and the owned TCP+TLS loop) - ADR-014: Secret material flow and capability injection (defines the "assembly layer" term — the deployment binary that composes crates) - ADR-010 Amendment 1: TCP+TLS as sibling (superseded — TCP+TLS is now an owned transport, not a sibling; `dispatch` is public for SSH/WT, not for TCP+TLS) - ADR-027 §5: ACME ALPN challenge handling (location amended — guard moves from `dispatch_quinn` to shared `dispatch`) - ADR-065: `Connection::from_stream`/`from_bidi` (the primitive that makes TCP+TLS dispatch possible; `Connection::close` is transport-abstracted, so the `acme-tls/1` guard works uniformly) - ADR-082: `alknet-tls` extraction (amended — endpoint takes no `Arc`; the assembly layer builds transports from `TlsServerConfig`s) - ADR-080: `ChannelClient::from_connection` (the transport-agnostic client pattern this ADR mirrors on the server side) - `docs/research/alknet-endpoint-refactor/findings.md` — the analysis that surfaced the conflation and the two-config hub case - `docs/architecture/crates/endpoint/README.md` — the canonical spec for `alknet-endpoint` (this ADR's amendment is the decision; that spec is the description) - `crates/alknet-core/src/endpoint.rs` — the code being extracted into `alknet-endpoint` (the old module becomes a deletion after the extraction) - OQ-60: resolved — transport construction is inlined by the assembly layer (the deployment binary); the TCP+TLS loop lives in `alknet-endpoint` behind a `tcp` feature as an owned transport - OQ-61: dissolved — the multi-owner shutdown problem does not arise; the endpoint owns all its accept loops (quinn, iroh, TCP+TLS)