revert(nests): drop moq-lite-04 ALPN advertisement (codec is wire-incompatible)

Re-investigation of `kixelated/moq` commit 45db108 ("moq-lite/moq-relay:
hop-based clustering") revealed that Lite-04 IS wire-incompatible with
our Lite-03 codec on Announce / AnnounceInterest / Probe — contradicting
the earlier reasoning that motivated 4b73626. Specifically:

  - Announce.hops: Lite-03 writes a single varint count of hops; Lite-04
    writes count + count × varint Origin ids. (`rs/moq-lite/src/lite/
    announce.rs:67-73` branches on Version explicitly.)

  - AnnounceInterest: Lite-04 added an `exclude_hop` varint after the
    prefix.

  - Probe: Lite-04 added an `rtt` varint after `bitrate`.

Subscribe / SubscribeOk / SubscribeDrop / Group / GroupHeader framing is
unchanged across Lite-03↔Lite-04 — but the Announce/Probe drift alone is
enough to desync a Lite-04-preferring relay if it picks `moq-lite-04`
from our advertised list. We'd encode Announce hops as a bare varint
where the peer expects `len + len × u62`, and the connection aborts on
the first Announce exchange.

Pin `wt-available-protocols` back to `["moq-lite-03"]` until
`MoqLiteCodec` gains version-aware Announce / AnnounceInterest / Probe
codecs and `MoqLiteAnnounce.hops` becomes a list rather than a single
varint. Reverting 4b73626 — the LITE_04 constant stays in MoqLiteAlpn
for documentation, but is no longer plumbed into the factory's
sub-protocol list.

Reverts the wire-format expansion in 4b73626. The factory and ALPN
kdocs are rewritten to spell out the codec diff so the next person who
considers re-enabling Lite-04 reads the actual blocker first.

https://claude.ai/code/session_014JfZJHSTvyYYWJbC9VbB47
This commit is contained in:
Claude
2026-05-06 17:37:02 +00:00
parent 1c47fd2403
commit ea90685a86
2 changed files with 42 additions and 18 deletions
@@ -21,22 +21,38 @@
package com.vitorpamplona.nestsclient.moq.lite
/**
* moq-lite ALPN strings. The on-the-wire framing for Subscribe / Group
* / Announce did NOT change between Lite-03 and Lite-04, so advertising
* both via `wt-available-protocols` is safe — the relay picks whichever
* it prefers and our existing codec paths handle either. We keep 03 in
* the list as the previously-tested target until the production relay's
* Lite-04 path has interop coverage.
* moq-lite ALPN strings. ONLY [LITE_03] is wire-compatible with the
* codec in [MoqLiteCodec]; the other constants are kept for
* documentation and future codec upgrades.
*
* Subscribe / Group framing is identical across Lite-03 and Lite-04,
* but Lite-04 reshapes Announce.hops into an `OriginList`
* (`kixelated/moq` commit 45db108, "moq-lite/moq-relay: hop-based
* clustering"), adds an `exclude_hop` field to AnnounceInterest, and
* adds an `rtt` field to Probe. A relay that picks Lite-04 with our
* Lite-03 codec on the wire desyncs on the first Announce exchange.
* Don't add [LITE_04] to `wt-available-protocols` until
* [MoqLiteCodec] is version-aware and [MoqLiteAnnounce.hops] is a
* list rather than a single varint.
*
* `"moql"` is the legacy combined ALPN that requires an in-band SETUP
* exchange — kept here for completeness; not advertised by the
* factory.
*
* Source: `kixelated/moq-rs/rs/moq-lite/src/version.rs:21-26`,
* `@moq/lite/connection/connect.js:277`.
* Source: `kixelated/moq/rs/moq-lite/src/lite/version.rs`,
* `kixelated/moq/rs/moq-lite/src/lite/announce.rs:11-105`,
* `kixelated/moq/rs/moq-lite/src/lite/probe.rs:9-55`.
*/
object MoqLiteAlpn {
const val LITE_03: String = "moq-lite-03"
/**
* `moq-lite-04` ALPN string. Wire-incompatible with [MoqLiteCodec]
* today — see the object kdoc for the codec diff. Defined here so
* a future patch that lands version-aware Announce / Probe codecs
* can drop it into the [QuicWebTransportFactory] sub-protocol list
* without re-deriving the constant.
*/
const val LITE_04: String = "moq-lite-04"
const val LEGACY: String = "moql"
}
@@ -91,18 +91,26 @@ class QuicWebTransportFactory(
* `connection closed err=invalid value` on the relay side and a stalled
* subscribe / `subscribe stream FIN before reply` on the client side.
*
* `moq-lite-04` is also advertised because the production relay
* (moq.nostrnests.com) and the kixelated browser client both ship
* Lite-04 now; without it in our list a Lite-04-only deployment
* would refuse the CONNECT. The on-the-wire framing for Subscribe /
* Group / Announce did NOT change between Lite-03 and Lite-04, so
* our existing codec handles either selection. List `moq-lite-03`
* first because it's our previously-tested negotiation target —
* a relay that supports both should pick the listed-first option,
* and a Lite-04-only relay falls through to the second entry.
* **Lite-04 is intentionally NOT advertised** even though the kixelated
* browser client now ships it. Lite-04 reshapes the on-the-wire
* Announce.hops field from a single varint count into a full
* `OriginList` (`kixelated/moq` commit 45db108, "moq-lite/moq-relay:
* hop-based clustering"), adds an `exclude_hop` field to
* AnnounceInterest, and adds an `rtt` field to Probe — Subscribe and
* Group framing are unchanged but Announce framing diverges. Our codec
* speaks pure Lite-03; if a Lite-04-preferring relay picks
* `moq-lite-04` from our advertised list, the very first Announce
* exchange would desync (we'd encode/read a bare hops varint where
* the peer expects `len + len × u62`) and the connection would abort.
* Until [com.vitorpamplona.nestsclient.moq.lite.MoqLiteCodec] gains
* version-aware Announce / AnnounceInterest / Probe paths and
* [com.vitorpamplona.nestsclient.moq.lite.MoqLiteAnnounce.hops]
* becomes a list, advertising Lite-04 is a footgun. See
* [com.vitorpamplona.nestsclient.moq.lite.MoqLiteAlpn] for the
* known-version constants.
*/
private val webTransportSubProtocols: List<String> =
listOf(MoqLiteAlpn.LITE_03, MoqLiteAlpn.LITE_04),
listOf(MoqLiteAlpn.LITE_03),
) : WebTransportFactory {
override suspend fun connect(
authority: String,