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ADR-038 is superseded (its anti-pattern correction stands; its specific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parked, not superseded — their designs revive unchanged when WebTransport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.
A consistency review of the alknet-http specs found two classes of
issues: internal contradictions from the mid-spec pivot (the to_openapi
gateway pattern landed in prose but not in cross-references), and a
systematic client→server assumption that only holds for the OpenAPI/MCP
case leaking into the WebTransport architecture.
Class 1 (internal contradictions):
- C1: to_openapi was half-refactored — body described the ADR-042
gateway pattern but the decisions table and ADR-036 still said
'paths mirror /{service}/{op}'. ADR-036's to_openapi clause is now
amended as superseded by ADR-042; the stale decisions row and README
Principle 2 are fixed.
- C2: the axum Router route list didn't include the 5 gateway endpoints
(/search, /schema, /call, /batch, /subscribe). Added them; clarified
/openapi.json as the gateway description doc; added gateway paths to
the decoy exclusion list.
- C3: ADR-034 §5 still talked about the 'h3/WebTransport deferral
bucket' that ADR-038 eliminated. Amended §5/Consequences/References
to drop the deferral framing (the auth-model decision stands; only
the 'when' wording was stale).
Class 2 (one-way direction assumption):
- C4/C5/C6: the WebTransport specs framed the session as browser→hub
one-way, when the call protocol is bidirectional and WebTransport is
a general ALPN transport substrate. New ADR-043 reframes WebTransport
as a bidirectional ALPN transport substrate (call protocol is the
first/canonical target; needs no WASM parser), names the call
protocol's bidirectionality over WebTransport sessions, and states
the inbound no-PeerId connection-local overlay as the mirror of
ADR-034 §2. webtransport.md is updated to reflect this framing;
ADR-040 is repositioned (not superseded) as the substrate's non-call-
ALPN mechanism.
- C7: the HTTP/1.1+HTTP/2 surface's one-directionality is now named as
a lossy consequence of HTTP request/response; WebTransport is named
as the surface that restores the bidirectional call model.
- C8: overview.md acknowledges the from/to direction model is
OpenAPI/MCP-specific, not a call-protocol property.
A review subagent pass on ADR-043 + webtransport.md found no critical
issues; warnings W1-W3 (residual browser-as-subject framing, ADR-009
rationale in spec, opening abstract tone) and suggestions S2/S4/S5
were addressed.
