TypeScript DSL (taskflow-dsl)

S4 adds a compile-time TypeScript frontend. You author *.tf.ts with runes (agent, map, race, …). A CLI erases them to ordinary Taskflow JSON. Hosts still run JSON via taskflow_run / /tf run — there is no interpret path and no host auto-build of .tf.ts.

Workflow

# monorepo / built package
taskflow-dsl new audit
# edit audit.tf.ts
taskflow-dsl check audit.tf.ts
taskflow-dsl build audit.tf.ts --emit both
# → audit.taskflow.json (+ optional FlowIR)
# Then: taskflow_verify / taskflow_run with defineFile=audit.taskflow.json

decompile does not recover original variable names, formatting, comments, or source spelling. Supported definitions rebuild to semantically equivalent Taskflow/FlowIR; unsupported or lossy constructs fail instead of claiming a literal round-trip.

build, decompile, and new refuse to replace an existing output unless --force is explicit. All output paths must remain under --cwd; destination symlinks are rejected, and writes are atomically committed from a same-directory temporary file. With --emit both, both destinations are checked before either file is written.

Authoring shape

import { flow, agent, map, reduce, json, race, expand } from "taskflow-dsl";

export default flow("audit", (ctx) => {
  ctx.budget({ maxUSD: 2 });
  const discover = agent("List files under {args.dir}", {
    output: json<{ path: string }[]>(),
  });
  const each = map(discover, (item) => agent(`Audit ${item.path}`));
  return reduce([each], () => agent("Write one summary"));
});

Unbuilt .tf.ts must not be executed as a Node program — runes throw TFDSL_ERASE_ONLY.

Kinds ↔ runes (summary)

JSON still has 12 phase types. DSL runes erase to those kinds (plus sugars like gate.automated / gate.scored, expand.nested / expand.graft, subflow.def).

See monorepo skills configuration §9 and docs/rfc-0.2.0-s4-mvp.md.

Runtime boundary

• The TypeScript DSL is compile-time only; emitted JSON uses the same runtime.
• The event kernel remains opt-in (eventKernel or PI_TASKFLOW_EVENT_KERNEL=1). race and expand use the imperative path; score gates, onBlock: retry, reflexion, retry, expect, cross-run cache, and Shared Context Tree also force a safe imperative fallback.
• Not an MCP taskflow_build tool in the ship bar.

Next

• Phase Types — JSON kinds including race / expand
• Commands — host MCP / /tf surfaces
• Monorepo: docs/rfc-0.2.0-s4-mvp.md, docs/internal/claim-vs-impl-0.2.0.md

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