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docs(http): defer h3/WebTransport (ADR-044); browsers use WebSocket for v1

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Working through the WebTransport implementation path surfaced a scope
question distinct from the hedging-as-deferral anti-pattern ADR-038 was
written to correct. Three findings drove the re-evaluation:

1. The browser bidirectional call-protocol path doesn't require
   WebTransport — WebSocket is full-duplex, EventEnvelope fits a WS
   binary message boundary cleanly, and the Dispatcher is stream-
   agnostic (ADR-012). What WebTransport gives over WebSocket (native
   multi-stream multiplexing, the ALPN-as-stream substrate) benefits the
   proxy use case, not the call protocol.
2. WebTransport is a draft standard (-07, not RFC) on an experimental
   Rust dependency stack (wtransport/h3 both self-describe as not
   production-ready). Either choice puts a draft protocol on the
   security surface of the first release.
3. The ALPN-stream-proxy (ADR-040) is speculative — its WASM parser
   consumers (browser SSH/SFTP/git clients) don't exist yet, and the
   downstream crates WebTransport deferral blocks (SSH, git, SFTP)
   expose their ALPNs natively over QUIC regardless.

This is a scope decision (per ADR-009: a decision that 'genuinely
doesn't need to be made yet because the use case isn't concrete'), not
hedging. The reversal trigger is concrete: a real deployment needing
the ALPN-stream-proxy.

ADR-038 is superseded (its anti-pattern correction stands; its specific
'h3 in scope now' decision is reversed). ADR-040 and ADR-043 are
parked, not superseded — their designs revive unchanged when WebTransport
revives, with §2 (bidirectionality) and §3 (no-PeerId overlay) of ADR-043
transferring to WebSocket for v1.

ADR-044 §5 also states the 'browser is not a peer' rationale that
ADR-034 §4 closed without arguing: peer = addressable node in the
call-protocol peer graph (stable PeerId, PeerRef::Specific-reachable,
identity stable across reconnects), not 'any endpoint that exchanges
calls during a live session.' A browser is the second but not the first
(no stable crypto identity of its own, ephemeral, not addressable from
other nodes). ADR-034 §4 and Assumption 2 are amended by reference.

The wtransport-vs-hyperium dependency question is recorded (not
resolved — WebTransport is deferred) in ADR-044 §'Research note' and
webtransport.md so the revival doesn't re-derive it: wtransport probably
isn't the right choice (axum-bridge friction — it owns its own HTTP
serving path); the hyperium stack (h3 + h3-quinn + h3-webtransport) fits
the axum integration better but its server-side WebTransport API needs
verification before commitment.

Reviewed by architecture-review subagent; all critical cross-reference
issues (ADR-034 §5 stale 'in scope' assertion, ADR-036 Context listing
h3 as implemented, webtransport.md Design Decisions table) resolved.
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glm-5.2
2026-06-30 05:55:55 +00:00
parent 78b226d31b
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15
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@@ -18,9 +18,9 @@ The storage and auth strategy research (`docs/research/alknet-storage-strategy/f
The alknet-call crate is **implemented and reviewed** — both the server-side core and the client/adapter surface (207 lib + 2 integration tests passing). The alknet-core and alknet-call crate specs are in draft; the alknet-vault crate specs are stable.
**alknet-http specs drafted and consistency-reviewed.** The alknet-http crate (HTTP interface — `h2`/`http/1.1`/`h3` server + `from_openapi`/`to_openapi`/`from_mcp`/`to_mcp` adapters) now has architecture specs: [crates/http/](crates/http/) (overview, http-server, http-adapters, http-mcp, webtransport) and eight ADRs — [ADR-036](decisions/036-http-to-call-operation-mapping.md) (HTTP-to-call mapping; direct-call surface), [ADR-037](decisions/037-mcp-stdio-transport-exclusion.md) (MCP stdio exclusion), [ADR-038](decisions/038-http3-and-webtransport-as-first-class.md) (HTTP/3 + WebTransport as first-class, correcting the Phase 0 deferral framing), [ADR-039](decisions/039-http-server-and-client-host-colocated.md) (HTTP server + client host colocated in one crate), [ADR-040](decisions/040-webtransport-alpn-stream-proxy.md) (WebTransport ALPN-stream-proxy — the substrate's mechanism for non-call ALPNs like SSH/git/SFTP via WASM parser; the "VPN-like without being a VPN" use case), [ADR-041](decisions/041-mcp-tool-gateway-pattern.md) (`to_mcp` tool-gateway pattern — 4 fixed gateway tools instead of one tool per operation, addressing LLM context tool-bloat), [ADR-042](decisions/042-openapi-gateway-pattern.md) (`to_openapi` gateway pattern — 5 fixed gateway endpoints instead of one path per operation; per-caller AccessControl-filtered API surface; supersedes ADR-036's original `to_openapi` clause), [ADR-043](decisions/043-webtransport-bidirectional-alpn-substrate.md) (WebTransport as a bidirectional ALPN transport substrate — reframes WebTransport as carrying ALPNs as bidirectional streams with the call protocol as the first/canonical target; names the call protocol's bidirectionality over WebTransport; states the inbound no-`PeerId` connection-local overlay as the mirror of ADR-034 §2). ADR-003 Amendment 1 clarifies that `alknet-call` is a protocol-foundation crate (the `alknet-http` → `alknet-call` dependency edge). A consistency review pass corrected drift from the mid-spec pivot (the `to_openapi` gateway pattern landed in the prose but not in cross-references; the WebTransport specs inherited the OpenAPI/MCP direction assumption that doesn't hold for the call protocol) — ADR-036's `to_openapi` clause is now amended as superseded by ADR-042, ADR-034 §5's "deferral bucket" wording is corrected (the decision stands), and the http specs now name the one-directional HTTP projection vs. the bidirectional WebTransport substrate. The specs are in draft; implementation has not started. Three open questions carried: OQ-38 (WebTransport standalone relay service scope — distinct from the in-process ALPN-stream-proxy resolved by ADR-040), OQ-39 (`to_openapi` published-spec versioning), OQ-40 (reqwest client config).
**alknet-http specs drafted and consistency-reviewed.** The alknet-http crate (HTTP interface — `h2`/`http/1.1` server + WebSocket browser path + `from_openapi`/`to_openapi`/`from_mcp`/`to_mcp` adapters) now has architecture specs: [crates/http/](crates/http/) (overview, http-server, http-adapters, http-mcp, webtransport) and nine ADRs — [ADR-036](decisions/036-http-to-call-operation-mapping.md) (HTTP-to-call mapping; direct-call surface), [ADR-037](decisions/037-mcp-stdio-transport-exclusion.md) (MCP stdio exclusion), [ADR-038](decisions/038-http3-and-webtransport-as-first-class.md) (HTTP/3 + WebTransport as first-class — **superseded by ADR-044**; its correction of the two-way-door-as-deferral anti-pattern stands, its specific decision is reversed by the scope deferral), [ADR-039](decisions/039-http-server-and-client-host-colocated.md) (HTTP server + client host colocated in one crate), [ADR-040](decisions/040-webtransport-alpn-stream-proxy.md) (WebTransport ALPN-stream-proxy — **parked** per ADR-044; revives unchanged when WebTransport revives), [ADR-041](decisions/041-mcp-tool-gateway-pattern.md) (`to_mcp` tool-gateway pattern — 4 fixed gateway tools instead of one tool per operation, addressing LLM context tool-bloat), [ADR-042](decisions/042-openapi-gateway-pattern.md) (`to_openapi` gateway pattern — 5 fixed gateway endpoints instead of one path per operation; per-caller AccessControl-filtered API surface; supersedes ADR-036's original `to_openapi` clause), [ADR-043](decisions/043-webtransport-bidirectional-alpn-substrate.md) (WebTransport as a bidirectional ALPN transport substrate — **parked** per ADR-044; §2/§3 transfer to WebSocket for v1), [ADR-044](decisions/044-defer-webtransport-browsers-use-websocket.md) (defer `h3`/WebTransport; browsers use WebSocket for the bidirectional call-protocol path; a scope decision per ADR-009 §"What this framework is NOT"; reversal trigger = a concrete ALPN-stream-proxy use case; states the "browser is not a peer" rationale — addressability vs. bidirectionality — that amends ADR-034 §4). ADR-003 Amendment 1 clarifies that `alknet-call` is a protocol-foundation crate (the `alknet-http` → `alknet-call` dependency edge). A consistency review pass corrected drift from the mid-spec pivot (the `to_openapi` gateway pattern landed in the prose but not in cross-references; the WebTransport specs inherited the OpenAPI/MCP direction assumption that doesn't hold for the call protocol) — ADR-036's `to_openapi` clause is now amended as superseded by ADR-042, ADR-034 §5's "deferral bucket" wording is corrected (the decision stands), and the http specs now name the one-directional HTTP projection vs. the bidirectional WebSocket (and, when revived, WebTransport) substrate. The specs are in draft; implementation has not started. Three open questions carried: OQ-38 (WebTransport standalone relay service scope — distinct from the in-process ALPN-stream-proxy resolved by ADR-040), OQ-39 (`to_openapi` published-spec versioning), OQ-40 (reqwest client config).
**Next step**: The storage/repo-pattern ADRs (030–033) are accepted and amend the core and call specs. The next implementation phase is the ADR-029 migration (peer-keyed overlays, `PeerRef` routing, retire `remote_safe`/`trusted_peer`) with the ADR-030 `PeerEntry` change and the ADR-032 `forwarded_for` field folded in — the `OperationContext`, `from_call` handler, and `AuthPolicy` are all under edit, making this the cheapest window. After that: alknet-http implementation (specs drafted, ADRs 036–038 proposed), which consumes the `CredentialStore` trait and the `OperationAdapter` contract. The alknet-ssh crate (the other post-core crate, specced in parallel) proceeds independently — it depends on `alknet-core`, not `alknet-call`.
**Next step**: The storage/repo-pattern ADRs (030–033) are accepted and amend the core and call specs. The next implementation phase is the ADR-029 migration (peer-keyed overlays, `PeerRef` routing, retire `remote_safe`/`trusted_peer`) with the ADR-030 `PeerEntry` change and the ADR-032 `forwarded_for` field folded in — the `OperationContext`, `from_call` handler, and `AuthPolicy` are all under edit, making this the cheapest window. After that: alknet-http implementation (specs drafted; `h3`/WebTransport deferred per ADR-044, browser bidirectional path uses WebSocket), which consumes the `CredentialStore` trait and the `OperationAdapter` contract. The alknet-ssh crate (the other post-core crate, specced in parallel) proceeds independently — it depends on `alknet-core`, not `alknet-call`.
## Architecture Documents
@@ -39,10 +39,10 @@ The alknet-call crate is **implemented and reviewed** — both the server-side c
| [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/http/README.md](crates/http/README.md) | draft | alknet-http crate index |
| [crates/http/overview.md](crates/http/overview.md) | draft | Crate purpose, two roles (server + client host), dependencies, adapter location map |
| [crates/http/http-server.md](crates/http/http-server.md) | draft | HttpAdapter for h2/http1.1, axum over QUIC, Bearer auth, stealth, /healthz |
| [crates/http/http-server.md](crates/http/http-server.md) | draft | HttpAdapter for h2/http1.1 + WebSocket browser path, axum over QUIC, Bearer auth, stealth, /healthz |
| [crates/http/http-adapters.md](crates/http/http-adapters.md) | draft | from_openapi (reqwest) and to_openapi (projection); no-env-vars injection point |
| [crates/http/http-mcp.md](crates/http/http-mcp.md) | draft | from_mcp / to_mcp (feature-gated), streamable-HTTP-only, stdio exclusion |
| [crates/http/webtransport.md](crates/http/webtransport.md) | draft | h3/WebTransport handler — the browser streaming path |
| [crates/http/webtransport.md](crates/http/webtransport.md) | deferred | h3/WebTransport handler — deferred per ADR-044; browser bidirectional path uses WebSocket (see http-server.md). Spec kept intact for revival. |
| [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) |
@@ -90,12 +90,13 @@ The alknet-call crate is **implemented and reviewed** — both the server-side c
| [035](decisions/035-concrete-persistence-adapter-shapes.md) | Concrete Persistence Adapter Shapes — Read/Write Split, honker+SQLite | Accepted |
| [036](decisions/036-http-to-call-operation-mapping.md) | HTTP-to-Call Operation Mapping | Proposed |
| [037](decisions/037-mcp-stdio-transport-exclusion.md) | MCP Stdio Transport Exclusion | Proposed |
| [038](decisions/038-http3-and-webtransport-as-first-class.md) | HTTP/3 and WebTransport as First-Class HTTP Transports | Proposed |
| [038](decisions/038-http3-and-webtransport-as-first-class.md) | HTTP/3 and WebTransport as First-Class HTTP Transports | ~~Proposed~~ → **Superseded** by ADR-044 |
| [039](decisions/039-http-server-and-client-host-colocated.md) | HTTP Server and Client Host Colocated in alknet-http | Proposed |
| [040](decisions/040-webtransport-alpn-stream-proxy.md) | WebTransport ALPN-Stream-Proxy | Proposed |
| [040](decisions/040-webtransport-alpn-stream-proxy.md) | WebTransport ALPN-Stream-Proxy | Proposed — **parked** (implementation deferred per ADR-044) |
| [041](decisions/041-mcp-tool-gateway-pattern.md) | MCP Tool-Gateway Pattern for to_mcp | Proposed |
| [042](decisions/042-openapi-gateway-pattern.md) | OpenAPI Gateway Pattern for to_openapi | Proposed |
| [043](decisions/043-webtransport-bidirectional-alpn-substrate.md) | WebTransport as a Bidirectional ALPN Transport Substrate | Proposed |
| [043](decisions/043-webtransport-bidirectional-alpn-substrate.md) | WebTransport as a Bidirectional ALPN Transport Substrate | Proposed — **parked** (implementation deferred per ADR-044; §2/§3 transfer to WebSocket) |
| [044](decisions/044-defer-webtransport-browsers-use-websocket.md) | Defer h3/WebTransport; Browsers Use WebSocket | Accepted |
## Open Questions