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ADR-038 is superseded (its anti-pattern correction stands; its specific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parked, not superseded — their designs revive unchanged when WebTransport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.
