Choose Your Control Plane Source

The main architecture decision behind sof-tx is not "RPC or direct send." It is where leader, TPU, slot, topology, and recent blockhash state comes from.

The Four Real Options

1. Static or manually supplied inputs

Use when:

• you are testing
• your targets are fixed by another system
• you only need sof-tx as a submission client

Tradeoff:

• simplest integration
• weakest freshness guarantees unless your external source is strong

2. External dynamic control plane

Use when:

• you already run an internal service for blockhash, leaders, or TPU routing
• you do not want a local observer/runtime in the same process

Tradeoff:

• clear separation of concerns
• freshness and failure behavior now depend on that external service

3. Live in-process SOF adapter

Use when:

• one service both observes traffic and submits transactions
• you want the freshest local view the host can provide
• restart replay is less important than tight local coupling

Tradeoff:

• best in-process freshness for that host
• adapter state is process-local unless you add your own persistence
• complete today with raw-shred and gossip SOF runtimes
• built-in processed provider adapters are still not a full sof-tx control-plane source by themselves, but the packaged runtime can now combine built-in provider transactions with gossip-derived cluster topology when you use PluginHostTxProviderAdapter::topology_only(...)

4. Replayable SOF-derived control plane

Use when:

• the service must recover after restart without rebuilding all control-plane state from scratch
• you need checkpointing and replay semantics
• you are building a longer-lived stateful execution service

Tradeoff:

• strongest restart posture
• more moving parts and more integration work
• assumes a runtime that emits the full control-plane feed, not only the narrower built-in processed-provider event surface

Recommended Starting Point

Most teams should pick one of these:

1. sof-tx with external providers if they already have a control-plane service
2. sof plus sof-tx with the live plugin adapter if they want one local service
3. derived-state adapter only after restart recovery becomes a hard requirement

Quick Mapping

Your control-plane source directly affects:

• whether DirectOnly or Hybrid is trustworthy
• how much stale-state risk you carry
• whether flow-safety checks reject valid sends or miss bad ones
• how cleanly the service recovers after restart