alknet/docs/architecture/open-questions.md

status, last_updated

status	last_updated
draft	2026-06-20

Open Questions

Questions are organized by theme. Each question has a stable OQ-ID for cross-referencing from spec documents.

Door type classifications follow ADR-009:

• One-way door: Reversal requires rewriting significant code or permanently closes a capability. Requires ADR before implementation.
• Two-way door: Reversal is cheap or additive. Can be decided during implementation.

Theme: Core Types

OQ-01: BiStream Type Definition

• Origin: overview.md
• Status: resolved
• Door type: One-way
• Priority: high
• Resolution: BiStream is a trait (AsyncRead + AsyncWrite + Send + Unpin). Handlers receive a Connection (not a single BiStream). This preserves the WASM door — browser clients can implement BiStream over WebTransport streams. See ADR-007.
• Cross-references: ADR-002, ADR-007, ADR-009

OQ-02: AuthContext Resolution Timing

• Origin: overview.md
• Status: resolved
• Door type: One-way
• Priority: high
• Resolution: Hybrid model (Option C) — endpoint resolves what it can (e.g., TLS client certificate), handler resolves what it must (e.g., AuthToken in first frame). AuthContext may be partial when handle() is called. See ADR-004.
• Cross-references: ADR-002, ADR-004

Theme: ALPN and Routing

OQ-03: ALPN String Naming Convention

• Origin: overview.md
• Status: resolved
• Door type: One-way
• Priority: medium
• Resolution: Custom ALPNs use alknet/<name> prefix (no version), standard ALPNs use IANA strings. No version negotiation initially. See ADR-006.
• Cross-references: ADR-001, ADR-006

OQ-04: Dynamic Handler Registration at Runtime vs Static at Startup

• Origin: overview.md

• Status: resolved

• Door type: Two-way

• Priority: low

• Resolution: Static registration at startup. HandlerRegistry is immutable after construction. ALPN strings in the TLS ServerConfig are derived from the registry at startup — adding a handler at runtime requires rebuilding the TLS config. The ArcSwap<HandlerRegistry> pattern can be applied later if needed (two-way door). See ADR-010.

  Scope clarification (ADR-024): This resolution applies to the HandlerRegistry (ALPN string → ProtocolHandler), which is what ADR-010 governs. The call protocol's OperationRegistry (operation name → HandlerRegistration) is a separate registry living inside the CallAdapter, behind the single ALPN alknet/call. Its mutability profile is governed by ADR-024, not by this OQ. ADR-024 layers the operation registry by trust boundary: curated Local ops are immutable (same rationale as here — composing ops are privileged, the startup trust boundary is where their authority is granted); Session and imported (FromCall etc.) ops are dynamic at their respective trust-boundary scopes (session, connection). The pre-ADR-024 blanket immutability claim in operation-registry.md was inherited by analogy from this OQ and did not actually apply — the TLS-config argument that justifies HandlerRegistry immutability does not touch the OperationRegistry.

• Cross-references: ADR-001, ADR-010, ADR-024, endpoint.md, operation-registry.md

Theme: Transport and Endpoint

OQ-05: Multi-Connectivity Endpoint

• Origin: overview.md
• Status: resolved
• Door type: One-way
• Priority: high
• Resolution: AlknetEndpoint supports both quinn::Endpoint (public QUIC+TLS) and iroh::Endpoint (P2P relay-assisted) simultaneously, both optional and feature-gated. Both produce QUIC connections that dispatch through the same HandlerRegistry by ALPN string. These are not interchangeable transports — they serve fundamentally different deployment contexts (public IP vs NAT traversal). TCP is not an endpoint concern — bare TCP SSH is handled by the SSH handler directly. See ADR-010.
• Cross-references: ADR-001, ADR-010, endpoint.md

OQ-06: Server-Side ALPN vs Client-Side ALPN

• Origin: ADR-001
• Status: resolved
• Door type: One-way
• Priority: low
• Resolution: One ALPN per connection. Clients open one QUIC connection per ALPN. QUIC connections are cheap (multiplexed over the same UDP flow). See ADR-006.
• Cross-references: ADR-001, ADR-006

Theme: Call Protocol

OQ-07: Call Protocol Scope Within a Connection

• Origin: ADR-005
• Status: resolved
• Door type: Two-way
• Priority: medium
• Resolution: The call protocol uses bidirectional QUIC streams with EventEnvelope framing and ID-based correlation via PendingRequestMap. The protocol is stream-agnostic — the client can open one stream per operation, multiplex on one stream, or any mix. Correlation is by request ID, not by stream. Both sides can initiate calls. One alknet/call connection gives access to the full operation registry (call, subscribe, batch, schema). No multiplexing layer is needed inside the connection. See ADR-012.
• Cross-references: ADR-005, ADR-012

Theme: Security

OQ-08: Vault Integration Point

• Origin: overview.md
• Status: resolved
• Door type: One-way
• Priority: medium
• Resolution: CLI-embedded, assembly-layer only. The CLI binary instantiates VaultServiceHandle locally at startup, derives and decrypts the credentials each handler needs, and injects them into handler capabilities. alknet-vault has no ALPN, no alknet-core dependency, and no operations registered in the call protocol. The master seed and derived private keys never cross the network. The vault is a capability source, not a network service. See ADR-008 and ADR-014.
• Cross-references: ADR-003, ADR-005, ADR-008, ADR-014

Deferred Questions

These questions are acknowledged but not active. They will be promoted to open when their crate is being specified.

OQ-09: WASM Target Boundaries

• Origin: overview.md
• Status: deferred
• Door type: One-way (when applicable)
• Priority: low
• Resolution: Not an active question — WASM compatibility is a design constraint (see ADR-009, overview.md design principles), not a deliverable. Specific WASM targeting decisions will be made when individual crates are implemented. BiStream being a trait preserves the client-side stream door — a browser can implement BiStream over WebTransport streams. The server-side dispatch door is NOT preserved by ADR-007 and is a known, accepted closure: Connection is a concrete quinn-bound struct (not a trait), the accept loop uses tokio::spawn (tokio does not run on WASM), and the call-protocol dispatch internals (PendingRequestMap, CallAdapter) use tokio oneshot/mpsc channels. A WASM server-side peer would require a Connection trait and a runtime-abstracted accept loop — not planned. The browser path is client-side via a JS SDK, not server-side Rust-to-WASM. This is an explicit one-way door, not an oversight.
• Cross-references: ADR-007, ADR-009

OQ-10: Git Adapter Scope — Smart Protocol Only or Full Server?

• Origin: overview.md
• Status: deferred
• Door type: Two-way
• Priority: low
• Resolution: Deferred per the cleanup plan. Start with git smart protocol over QUIC streams. ERC721 integration and full server capabilities are additive. Composability fork (review #002 W18): whether git operations are registered in the OperationRegistry and callable via env.invoke(), or only available as raw smart protocol on alknet/git, is a separate decision from ERC721 scope. The path of least resistance (raw smart protocol only) forecloses agent composition of git operations — an agent handler that wants to compose git/clone cannot, because there's no OperationSpec, no Handler, no registration. To make git composable, a call-protocol projection (a set of HandlerRegistration bundles wrapping git operations behind the registry) must be built alongside or instead of the raw handler. Resolve this when speccing alknet-git, not deferred past it.
• Cross-references: ADR-001

Theme: alknet-core

OQ-11: Handler-Level Auth Resolution Observability

• Origin: auth.md

• Status: resolved

• Door type: Two-way

• Priority: medium

• Resolution: Option B — handlers store resolved identity on the Connection. When a handler resolves identity inside handle() (the handler-level auth phase), it calls connection.set_identity(identity) to store the resolved Identity on the connection object. The endpoint and observability layers can read it later for connection logging, audit trails, and metrics.

  Why not Option A (return identity from handle()): it changes the ProtocolHandler trait signature for all handlers, even those that don't do auth resolution (DNS, health check). It also assumes one identity per connection — but the call protocol can have different identities per request on the same connection (one connection, multiple call.requested events with different auth tokens). Returning a single identity from handle() would be misleading for the call protocol.

  Why not Option C (identity stays local): the resolved identity is useful beyond the handler. The endpoint may want to log "connection from X authenticated as Y." A connection-level observability layer needs the identity. If it stays local, every handler that resolves identity would need to duplicate logging logic, and the endpoint can't correlate connections to identities.

  Two identity scopes exist and must not be conflated:

  • Connection-level identity (this decision): set once by the handler in handle(), stored on Connection, read by the endpoint for logging/observability. This is the "connection owner" — who opened this QUIC connection.
  • Per-request identity (already in the call protocol spec): set per call.requested by the CallAdapter, stored on OperationContext.identity. This is the "call caller" — who is making this specific call, which may upgrade mid-session (different auth tokens on the same connection).

  Both exist. The connection-level identity is the stable "who is this connection from"; the per-request identity is the dynamic "who is this specific call from." The call protocol's per-request resolution (which may produce a different identity than the connection-level resolution) takes precedence for ACL on OperationContext — the connection-level identity is for observability only, not for ACL.

  C13 resolution (review #002): the endpoint does not read identity() after handle() returns. The Connection is moved into the spawned handler task (endpoint.md), so the endpoint no longer has a reference to it. Connection-level observability (remote addr, ALPN, connection ID) is logged by the endpoint before the move. Identity-level observability is logged by the handler (the handler knows which identity it resolved and can log it). There is no Arc<Connection> sharing or channel-based identity-reporting mechanism — the simplest honest answer that avoids over-engineering the observability path before there's a demonstrated need. If a future use case requires the endpoint to correlate connections to identities, an Arc<Connection> or a side-channel can be added then.

• Cross-references: ADR-004, ADR-011, ADR-015 (per-request identity on OperationContext), auth.md

OQ-12: TLS Identity Provisioning in AlknetEndpoint

• Origin: endpoint.md, config.md

• Status: resolved

• Door type: One-way

• Priority: high

• Resolution: TLS identity in alknet has two distinct use cases, not one:

  Use case 1 — P2P / key-based identity (default for most alknet nodes): RFC 7250 raw Ed25519 public keys. No domain, no CA, no cert renewal. The Ed25519 public key IS the node's identity. This is the same model iroh uses with its NodeId. It works natively with SSH auth (same key type) and git (SSH key-based auth). TlsIdentity::RawKey in StaticConfig covers this. This is the primary identity mode for alknet-native clients — most nodes will use this.

  Use case 2 — Domain-hosted services (relays, public-facing nodes): X.509 certificates with domain names. Required for browser/WebTransport clients, which don't support RFC 7250. This has two sub-cases:

  • Manual: Provide cert/key file paths via TlsIdentity::X509. Already specified in StaticConfig.
  • ACME auto-provisioning: Let's Encrypt via rustls-acme. The reverse-proxy project (/workspace/@alkdev/reverse-proxy) demonstrates the complete pattern: per-listener ACME state machine, ResolvesServerCertAcme rustls integration, TLS-ALPN-01 challenge handling, automatic renewal. This is a proven, solved implementation pattern — not speculative future work. It will be adapted to alknet's AlknetEndpoint context when domain-hosted nodes need it.

  Browser constraint: Browsers require X.509 and don't support RFC 7250. For browser/WebTransport clients, domain-hosted nodes with X.509 certs are mandatory. All other clients (SSH, git, alknet-native) work with raw keys by default.

  The TlsIdentity enum in StaticConfig already captures all three modes (X509, RawKey, SelfSigned). ACME auto-provisioning is additive — it produces an X.509 cert at runtime rather than from files, and fits naturally as an additional TlsIdentity variant or as a rustls::ResolvesServerCert implementation behind the existing X509 path.

• Cross-references: ADR-010, config.md, endpoint.md

OQ-13: Operation Path Format and Routing Scope

• Origin: operation-registry.md
• Status: resolved
• Door type: Two-way
• Priority: medium
• Resolution: alknet-call uses /{service}/{op} (e.g., /fs/readFile, /agent/chat, /services/list). This is the correct format for the alknet-call crate — it is not a "Phase 1 simplification" but the right design for this architecture. The /{node}/{service}/{op} pattern from the reference implementation served a head/worker routing model that is a separate architectural concern. Remote dispatch (federation / node-level routing) would be a different mechanism at a different layer, not a prefix added to alknet-call's operation paths. If remote dispatch is ever needed, it would be addressed by a separate crate or a routing layer above the operation registry, not by changing alknet-call's path format. Two-way door — the path format can be extended later if needed, but /{service}/{op} is the correct design now.
• Cross-references: ADR-005, ADR-012

OQ-14: Batch Operation Semantics

• Origin: call-protocol.md
• Status: resolved
• Door type: Two-way
• Priority: low
• Resolution: Batch is a client-side pattern — multiple call.requested events with correlated IDs, responses arrive independently. This is the correct protocol design, not a simplification to be "upgraded" later. QUIC's stream multiplexing already provides the concurrency and ordering guarantees that batch would need. Batch-specific event types (e.g., batch.requested, batch.responded) would add protocol complexity without clear benefit over sending multiple call.requested events. If a compelling use case for atomic batch semantics emerges, it can be added as a new event type without breaking existing clients. Two-way door.
• Cross-references: ADR-012

Theme: alknet-call

OQ-15: Call Protocol Client and Adapter Contract

• Origin: call-protocol.md, operation-registry.md, ADR-013
• Status: resolved
• Door type: One-way
• Priority: high
• Resolution: CallClient opens QUIC connections and shares the dispatch loop with CallAdapter — both sides can send and receive call.requested once connected. Connection direction (who opened the connection) is independent of call direction (who calls whom). from_call adapter discovers remote operations via services/list + services/schema and registers them with forwarding handlers — same pattern as from_openapi and from_mcp. to_openapi and to_mcp project local operations to external protocols. Adapter contract trait (OperationAdapter) produces (OperationSpec, Handler) pairs. Cross-node call tree: abort cascade (ADR-016) propagates across node boundaries through from_call handlers. Credentials for connections come from capabilities (ADR-014). Adapter-registered operations are Internal by default (ADR-015). See ADR-017.
• Cross-references: ADR-005, ADR-013, ADR-014, ADR-015, ADR-016, ADR-017, call-protocol.md, operation-registry.md

OQ-16: Safe Vault Operations for Call Protocol Exposure

• Origin: operation-registry.md, ADR-008
• Status: resolved
• Door type: One-way
• Priority: high
• Resolution: No vault operations are exposed over the call protocol for now. The vault is accessed only at the assembly layer (CLI binary at startup). Handlers receive secret material through OperationContext.capabilities, not by calling vault operations over the wire. The operation-registry.md spec previously showed vault/derive, vault/unlock, and vault/decrypt registered as call protocol operations — that was a contradiction with ADR-008's "capability source" model and has been corrected. If a future use case requires exposing a vault operation over the call protocol (e.g., a restricted vault/public-key operation that returns only public key material for identity verification), it would require its own ADR with an explicit threat model justification. See ADR-014.
• Cross-references: ADR-008, ADR-014, operation-registry.md

OQ-17: Abort Cascade Semantics for Nested Calls

• Origin: call-protocol.md, operation-registry.md
• Status: resolved
• Door type: One-way (protocol schema), two-way (mechanism)
• Priority: high
• Resolution: call.aborted cascades to all non-terminal descendants in the call tree. The CallAdapter walks the tree (indexed by parent_request_id in PendingRequestMap) and sends call.aborted for each descendant. Default policy is abort-dependents (abort everything downstream); continue-running is an opt-in for long-running work that should survive a parent's abort. Handlers clean up via Rust's async drop semantics (future dropped → Drop guards release resources). The cascade is protocol-level (server discovers descendants and propagates); the mechanism (parent-indexed map, cancellation tokens, or a separate graph) is a two-way door. See ADR-016.
• Cross-references: ADR-012, ADR-015, ADR-016, call-protocol.md, operation-registry.md

OQ-18: Privilege Model and Authority Context

• Origin: operation-registry.md
• Status: resolved
• Door type: One-way (ACL model), two-way (specific APIs)
• Priority: high
• Resolution: The internal flag on OperationContext marks calls that originated from composition (a handler calling another operation via OperationEnv), as opposed to external calls that arrived as call.requested from a wire client. The internal flag switches the authority context: the ACL check runs against the composing handler's identity (set at registration), not the caller's identity and not as a blanket skip. This replaces the previous trusted flag, which skipped ACL entirely — a privilege escalation vector. Operations have External/Internal visibility. Internal operations return NOT_FOUND when called from the wire and are excluded from services/list. The composition env is scoped — a handler can only invoke a declared set of operations. Handler identity is carried on OperationContext alongside caller identity (the principal/agent pair). See ADR-015.
• Cross-references: ADR-014, ADR-015, call-protocol.md, operation-registry.md

OQ-19: Session-Scoped Operation Registries and Agent-Written Operations

• Origin: operation-registry.md

• Status: resolved

• Door type: Two-way (protocol doesn't need changes), one-way (if implementation closes the door)

• Priority: medium

• Resolution: The call protocol supports session-scoped registries through OperationEnv trait layering. No protocol changes needed. The pattern is documented here and in operation-registry.md to prevent an implementation from accidentally closing it.

  The registry model has three tiers:

  Tier	Scope	Lifetime	Visibility	Who populates it
  Core (global)	All sessions	Process lifetime, static at startup	External + Internal (curated)	Assembly layer at startup
  Session	One session	Session lifetime, dynamic	Internal only (never wire-facing)	Agent during session (sandbox)
  Promotion	Session → Core	One-time transition	Manual/curated review	Human or architect agent reviews, then redeploys

  Session-scoped operations are always Internal (ADR-015), run under the handler's identity (the agent handler that authorized the sandbox), can only compose operations in the handler's scoped env, and are ephemeral (gone when the session ends). Core operations are curated — reviewed before promotion. The promotion path is the curation checkpoint where autonomous (session-scoped) becomes curated (core). This is not auto-promotion.

  Implementation guard: OperationEnv must remain a trait, not a concrete type. A session-scoped env wraps the global env (check session registry first, fall through to global). Making OperationEnv concrete or hardcoding the global registry into the dispatch path would close this pattern. The static registration constraint (OQ-04) applies to the curated (Layer 0) registry only; session registries are dynamic by nature and are a different registry overlaying the curated one. Generalized by ADR-024: connection-scoped remote imports (from_call) use the same overlay mechanism as session-scoped ops. Both are per-scope dynamic overlays on the static curated base, composed into the per-call OperationContext.env by the CallAdapter. OperationEnv being a trait object (Arc<dyn OperationEnv + Send + Sync>) is what enables both overlay patterns.

  Session-scoped operations run in a locked-down sandbox (no direct net/fs/env access), can only reach operations in the handler's scoped env, and their output should be validated against their declared schema before returning. The promotion path requires review — an agent with a promote scope (the architect role) performs the promotion; the writing agent (lower-privileged role) requests it. This is the role-based escalation pattern (ADR-015): privileges escalate through a chain of command, not through direct authority.

  The agent-specific mechanism (quickjs sandbox, session registry lifecycle, promotion workflow) belongs to the agent crate spec. The call protocol's job is to keep the OperationEnv trait composable and the visibility/ACL model consistent across tiers.

• Cross-references: OQ-04, ADR-014, ADR-015, ADR-016, ADR-024, operation-registry.md

Theme: alknet-vault

OQ-20: Salt/KDF and Encryption Key Derivation Method

• Origin: encryption.md
• Status: resolved
• Door type: One-way (key derivation method), two-way (salt field usage)
• Priority: high
• Resolution: The vault uses SLIP-0010 HD derivation from the BIP39 seed at path m/74'/2'/0'/0' to produce the AES-256-GCM encryption key — not PBKDF2. The salt field in EncryptedData is unused for key derivation (kept for wire-format compatibility with the TS predecessor). The TypeScript @alkdev/storage crypto module used PBKDF2 with a password + salt; data encrypted by that method (key_version=1) cannot be decrypted by the vault and must be migrated via one-time re-encryption to key_version=2. See ADR-020 for the full rationale and migration path.
• Cross-references: ADR-020, encryption.md

OQ-21: Remote Vault Administration

• Origin: service.md, protocol.md, ADR-019

• Status: resolved

• Door type: One-way (vault crate is local-only by construction)

• Priority: medium

• Resolution: Remote vault access is not a feature of the vault crate. ADR-025 dropped irpc from the vault, making the vault local-only by construction — no RemoteService trait, no wire format for vault messages, no default-insecure remote handler. The vault's API is VaultServiceHandle (direct method calls), nothing else.

  If remote vault access is ever needed (e.g., the machine→worker pattern), it requires a separate vault-server crate that depends on both alknet-core (for IdentityProvider, scopes, auth-wrapping) and alknet-vault (for VaultServiceHandle). That crate would define its own threat model, access policy, operation filtering (Unlock/Lock local-only), and wire format — and requires its own ADR. This is a deliberate addition, not a flag flip on a default that was already loaded.

  The pre-ADR-025 deferral framed remote access as "non-breaking" (the wire format was additive). That framing was misleading: once workers build dependencies on the remote vault API, disabling it breaks them — the door is operationally one-way even if the wire format is additive. ADR-025 inverts the default: the vault is local-only by construction, and remote access requires building something new, not removing a default.

  Per-node vaults are the recommended pattern for multi-node deployments: each node has its own vault and mnemonic; credentials are encrypted for the receiving node's public key, not decrypted centrally. This is end-to-end encryption between nodes, matching ADR-008's "capability source" model.

• Cross-references: ADR-005, ADR-008, ADR-014, ADR-018, ADR-019, ADR-025, protocol.md, service.md

OQ-22: Key Rotation Mechanism

• Origin: encryption.md
• Status: resolved
• Door type: One-way (path scheme), two-way (rotation policy)
• Priority: medium
• Resolution: Key rotation uses version-indexed derivation paths. Each key version maps to a distinct SLIP-0010 path: m/74'/2'/0'/{version-2}'. v2 (current) is at m/74'/2'/0'/0'; v3 is at m/74'/2'/0'/1'; etc. The decrypt method derives the key at the path indicated by encrypted.key_version (not always at PATHS::ENCRYPTION). The rotate method decrypts with the old version's key and re-encrypts with the new version's key — no new mnemonic needed. The assembly layer or a migration tool iterates stored blobs and calls rotate on each; the vault does not self-rotate. Partial rotation is safe (old keys remain derivable). See ADR-021.
• Cross-references: ADR-020, ADR-021, encryption.md, service.md

OQ-23: Handler Identity Registration Path and Composition Authority

• Origin: operation-registry.md, call-protocol.md, ADR-015
• Status: resolved
• Door type: One-way (security model), two-way (bundle shape)
• Priority: high
• Resolution: ADR-015 said handler identity was "set at registration by the assembly layer" but the registration API (register(spec, handler)) had no place for it — meaning every internal call would check ACL against None, reproducing the escalation gap ADR-015 was written to close. ADR-022 resolves this with a registration bundle (HandlerRegistration) carrying provenance, composition_authority (replacing handler_identity: Identity — it's a declared authority bundle, not a peer identity), scoped_env, and capabilities. The dispatch path (build_root_context and OperationEnv::invoke()) reads from the bundle. Provenance determines which ops can compose: only Local and Session get composition authority; leaves (FromOpenAPI, FromMCP, FromCall) get None — they don't compose, so they don't need it. Capabilities are per-request on OperationContext, populated from the bundle (resolving the closure-capture vs context ambiguity). The kernel/user analogy: user's authority checked once at the External gate; handler's composition authority used for all composition inside; scoped env bounds reachability. No intersection — the user's authority does not limit internal calls. See ADR-022.
• Cross-references: ADR-014, ADR-015, ADR-022, docs/reviews/001-pre-implementation-architecture-sanity-check.md (C1–C4), operation-registry.md, call-protocol.md

OQ-24: Operation Error Schemas

• Origin: operation-registry.md, call-protocol.md, ADR-017
• Status: resolved
• Door type: One-way (wire format), two-way (mapping mechanism)
• 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 ErrorDefinitions, 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, call-protocol.md