v0.9.0 "Convergent Crust"

Highlights

Ephemeral Messaging

New subduction_ephemeral crate for fire-and-forget messaging over Subduction connections. Supports presence indicators, cursor positions, typing indicators, and other transient signals that don't need persistence.

• Topic-scoped pub/sub via SedimentreeId
• Separate EphemeralPolicy for authorization (independent of StoragePolicy)
• ComposedHandler to multiplex sync and ephemeral traffic on a single connection

Byte-Level Transport

The Transport trait now operates at the byte level rather than message level, enabling:

• Simpler transport implementations
• Better separation of concerns (framing vs. serialization)
• Foundation for future protocol optimizations

Handler Architecture

New Handler trait and SubductionBuilder for cleaner connection management:

• Decoupled message handling from transport
• Composable handlers for sync, ephemeral, and custom protocols