REANNOUNCE via duplicate ANNOUNCE; announced() returns (path, Announced)

[kixelated]

Implements REANNOUNCE (per moq-dev/drafts#23). Rebased onto current dev.

REANNOUNCE is an atomic broadcast replacement: the broadcast at a path is swapped for a new one without an interruption in availability (relay failover, upstream restart, a shorter hop path arriving).

Wire design: duplicate ANNOUNCE = REANNOUNCE

Rather than an explicit status byte, a reannounce is a duplicate ANNOUNCE — an active announcement for a path that is already announced, with no intervening unannounce. This means:

• No wire-format change (lite/announce.rs is untouched), no new status, and no version gating — every version that speaks ANNOUNCE gets it.
• No JS change: a duplicate ANNOUNCE is idempotent for @moq/net's set-based announce consumers (reconnect republish, @moq/boy), so they keep working unchanged.

API change (Rust)

AnnounceConsumer::next() / try_next() / poll_next() now yield (PathOwned, Announced) instead of (PathOwned, Option<BroadcastConsumer>):

pub enum Announced {
    Active(BroadcastConsumer),
    Reannounce(BroadcastConsumer),
    Ended,
}

.broadcast() gives the legacy Option<BroadcastConsumer> view (Some for both Active and Reannounce, None for Ended), so callers that don't care about the distinction stay simple.

Behavior

• The origin already coalesced atomic replacements (backup promotion, shorter hop path) into an internal reannounce; those now surface as a single Announced::Reannounce delivery instead of an Ended-then-Active pair. A genuine unannounce+announce is still preserved as two deliveries.
• Lite publisher: a Reannounce is sent as a duplicate Announce::Active (keeping the stats guard for continuity).
• Lite subscriber: an Active for an already-announced path is applied as an atomic replacement (publish the replacement so the origin demotes the old broadcast to a backup, then retire it) instead of returning a Duplicate error.
• IETF moq-transport has no reannounce, so it splits a Reannounce into namespace_done + namespace.

Drive-by

Adds the missing compress field (..Default::default()) to libmoq's Track initializers, which fails to compile after dev's compression feature landed (this was the error[E0063]: missing field compress CI failure).

Tests

• model::origin: reannounce after the consumer drained is delivered as a single Reannounce; an undrained reannounce stays Active; test_duplicate backup-promotion asserts a single reannounce.
• moq-net 327 unit tests + moq-relay 93 lib tests pass; moq-net/moq-relay/moq-native/moq-ffi/libmoq/hang build clean with no clippy -D warnings; cargo fmt --all --check clean (verified on rust 1.96, the nix-pinned toolchain).

(Written by Claude)

[kixelated]

Maybe rename this to Announced::Restart? Or ::Retry?

[kixelated]

Renamed to Announced::Restart (and the internal restart-coalescing path) across moq-net + consumers. Went with Restart over Retry since restart is the status name in the draft (and "retry" reads like a failed attempt being re-sent, whereas this is a clean replacement). Happy to switch to Retry if you'd prefer. (Written by Claude)

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Generated by Claude Code