Draft

An immutable, inspectable dataflow graph that captures a distributed computation without running it.

Think of a Draft as a recipe, not a meal. It records what should happen — a dependency graph of named operations — but touches no data and invokes no code. This lets a planner inspect, rewrite, and optimise the graph before committing to execution (E-2 rewrites, E-3 cost model, E-5 incremental execution, G2–G5 DAG consolidation).

Structure — dependency DAG

A Draft is a directed acyclic graph of DraftNodes. Each node wraps a DraftStage and carries the set of NodeIds it depends on (DraftNode.predecessors). A linear pipeline — built by chaining map/filter/embroider — is the degenerate path: each node has exactly one predecessor.

Building a Draft

Start with Warp.shuttle, then chain map, filter, and optionally embroider:

val draft: Draft<ByteArray> = Warp.shuttle(OpId("docs"))
    .map(OpId("score"))
    .filter(OpId("above-threshold"))
    .embroider(OpId("rank"))

Inspecting a Draft

• nodes — all DraftNodes in topological order, with predecessor edges.

• stages — topological-order view of stage types; backward-compatible with E-5 consumers (ConvergentExecution) that iterate the stage sequence.

• isMonotone — true when every stage is CoordinationKind.Free; no consensus needed. The planner can run the whole pipeline coordination-free.

• embroideries — all DraftStage.Embroider nodes in topological order. A path has at most one; G2 combine can introduce more.

• embroidery — convenience accessor for the single DraftStage.Embroider, or null if none. Equivalent to embroideries.singleOrNull().

The no-execution guarantee

A Draft stores only symbolic OpIds — the names of registered operations. It has no access to an OpRegistry and no mechanism to invoke an Op. Nothing executes until E-5 provides a runtime.

Type Parameters

See also

Samples

val draft: Draft<ByteArray> = Warp.shuttle(OpId("docs"))
    .map(OpId("score"))
    .filter(OpId("above-threshold"))
    .embroider(OpId("rank"))

check(draft.stages.size == 4)
check(draft.isMonotone.not())          // has an Embroider stage
check(draft.embroidery?.opId == OpId("rank"))