The workflow DSL in the sandbox

Specifier: @nodetool-ai/sandbox-dsl. The root exports workflow() and every namespace under a short name. Each namespace is also its own module: @nodetool-ai/sandbox-dsl/nodetool.image, @nodetool-ai/sandbox-dsl/lib.audio, and so on for all 71.

Every node type is a generated function whose name and inputs come from the node's own metadata. A type this pack does not export does not exist, and the import fails before the program runs — which is the difference from building a graph out of type strings.

Build a graph

import { workflow } from "@nodetool-ai/sandbox-dsl";
import { stringInput } from "@nodetool-ai/sandbox-dsl/nodetool.input";
import { resize } from "@nodetool-ai/sandbox-dsl/nodetool.image";
import { output } from "@nodetool-ai/sandbox-dsl/nodetool.output";

const prompt = stringInput({ name: "prompt", value: "a fox in snow" });
const smaller = resize({ width: 256, height: 256 });
return workflow(output({ name: "image", value: smaller.output() }));

workflow() returns { nodes, edges } in the kernel shape — nodes carry {id, type, properties}, edges carry {id, source, sourceHandle, target, targetHandle}. Hand that straight to validate_workflow or create_workflow.

Check it, save it, run it

The graph is data until something checks it. Validate first — it costs nothing and catches a missing property, a dangling edge, or a model nobody selected before a run spends money on the half of the graph that does work:

import { validate_workflow, create_workflow, run_workflow, debug_workflow }
  from "@nodetool-ai/sandbox-nodetool/workflows";

const graph = workflow(output({ name: "image", value: smaller.output() }));

const check = await validate_workflow({ graph });
if (!check.ok) throw new Error(check.issues.map((i) => i.message).join("; "));

validate_workflow answers {ok, counts, issues} — ok is false only when the graph has errors, and each issue carries {severity, code, message}. Warnings do not set ok false; read them off issues.

const saved = await create_workflow({ name: "Thumbnailer", graph });
const run = await run_workflow({
  workflow_id: saved.id,
  params: { prompt: "a fox in snow" }
});

run_workflow answers {status, outputs}. When a run fails and the graph looks right, debug_workflow({workflow_id, params}) runs it again and answers one report: {workflow_id, run, job, workflow}. run carries {status, outputs, error, verdict} — outputs is keyed by output name and each name holds an array of emitted values (run.outputs.image[0]). job carries status, cost and logs; verdict.headline and verdict.issues say which node failed and why.

Every model property must be selected before you save: assign a find_model result's ref to the node's model. A graph saved with unselected models is refused by create_workflow, because nothing stamps models in at run time.

Where the session mounts no capability modules, the same three verbs are nodetool.workflows.validate/create/run/debug. Both forms reach one implementation past one permission gate.

Wiring

A node function returns a reference. ref.output() is the default output slot; ref.output("mask") names one. Pass a handle as a property value and the edge is wired for you:

const wired = resize({ image: source.output(), width: 512 });

A list[...] input takes an array of handles — one edge per element, and the sources run in parallel:

const strip = combineImageGrid({
  tiles: [a.output(), b.output(), c.output()],
  columns: 3
});

Every element must be a handle; mixing wired outputs and literal values in one array throws. A handle buried inside an object value throws too — a connection is only made from a handle assigned directly to an input.

A node with several outputs has no default, so output() without a slot throws and names the slots it has. A slot the node does not have throws the same way.

Ids

Ids are assigned from the node type: resize, resize_2, string_input. They are stable for a given program, so a later edit can name one — but the generated wrappers take inputs and nothing else, so a program cannot choose an id.

Everything in one import

import * as dsl from "@nodetool-ai/sandbox-dsl";

const smaller = dsl.image.resize({ width: 256, height: 256 });
return dsl.workflow(dsl.output.output({ name: "image", value: smaller.output() }));

The nodetool.* namespaces drop the prefix (dsl.image, dsl.input, dsl.text); the rest keep it in camel case (dsl.libAudio, dsl.openaiImage). Importing one namespace module is cheaper than the root, which pulls all 71.

Gotchas

• workflow() lives only at the root. A program that imports namespace subpaths still declares @nodetool-ai/sandbox-dsl for the builder.
• A handle is not text. `use ${node.output()}` throws rather than writing [object Object] into a property and wiring no edge.
• Only reachable nodes ship. workflow(terminal) walks back from its terminals; a node nothing wires to is dropped. Pass every terminal you want.
• One graph per call. workflow() clears the registry, so a handle from an earlier call is spent and using it throws.
• This builds a graph; it does not run one. The pack is pure computation — no models are called, no assets resolve, no node executes. Run the graph through the workflow tools once it validates.