fix(nestsclient): skip Active announce when AnnouncePlease prefix doesn't match — moq-lite Lite-03 announce.rs

Per moq-lite Lite-03 (kixelated/moq `rs/moq-lite/src/lite/announce.rs`), a publisher MUST only emit `Announce(Active)` for broadcasts whose path starts with the requested AnnouncePlease prefix. Pre-fix, when `MoqLitePath.stripPrefix(please.prefix, ourSuffix)` returned `null`, we fell through to `?: announcePublisher.suffix` and emitted Active under our full suffix anyway, falsely advertising the broadcast under a prefix the subscriber didn't request. Production never bit because the relay always opens its announce bidi to us with `prefix=""` (which always matches), but a future peer-to- peer or namespace-scoped subscriber would have observed a ghost broadcast under whatever prefix they asked about. The fix: if `stripPrefix` returns `null`, FIN the bidi cleanly without writing any Announce body. The subscriber sees an empty announce stream and moves on. Regression test: `MoqLiteSessionTest.publisher_skips_announce_when_announce_please_prefix_does_not_match`. Audit doc: nestsClient/plans/2026-05-09-moq-lite-rfc-compliance.md (M4). https://claude.ai/code/session_012TGfo99Ugz7fcCPv85a8Tq
2026-05-09 13:51:24 +00:00
parent 3a346968db
commit 6c2d7efccb
2 changed files with 58 additions and 2 deletions
@@ -838,8 +838,27 @@ class MoqLiteSession internal constructor(
                        MoqLiteControlType.Announce -> {
                            val pleasePayload = buffer.readSizePrefixed() ?: return@collect
                            val please = MoqLiteCodec.decodeAnnouncePlease(pleasePayload)
-                            val emittedSuffix =
-                                MoqLitePath.stripPrefix(please.prefix, announcePublisher.suffix) ?: announcePublisher.suffix
+                            // Per moq-lite Lite-03 (`rs/moq-lite/src/lite/announce.rs`),
+                            // a publisher MUST only emit Active for broadcasts whose
+                            // path starts with the requested prefix. If our suffix
+                            // doesn't match, FIN cleanly without writing any
+                            // Announce — the relay/peer sees an empty announce
+                            // stream and moves on. Pre-fix we'd fall through the
+                            // `null` branch of stripPrefix and falsely emit
+                            // `Active(suffix=ourFullSuffix)`, advertising under a
+                            // prefix the subscriber didn't ask for. Production
+                            // never bit because the relay always asks for
+                            // `prefix=""`, but a future peer-to-peer or
+                            // namespace-scoped subscriber would see a ghost.
+                            val emittedSuffix = MoqLitePath.stripPrefix(please.prefix, announcePublisher.suffix)
+                            if (emittedSuffix == null) {
+                                Log.w("NestTx") {
+                                    "ANNOUNCE inbound prefix='${please.prefix}' does not match publisher.suffix='${announcePublisher.suffix}' — FIN without Active"
+                                }
+                                runCatching { bidi.finish() }
+                                dispatched = true
+                                return@collect
+                            }
                            bidi.write(
                                MoqLiteCodec.encodeAnnounce(
                                    MoqLiteAnnounce(