From Legacy MLForm

Older examples used a class-shaped API:

const mlForm = new MLForm("/api/predict");
await mlForm.toHTMLElement(schema, container);

Use mountForm instead:

import { createJsonTransport, mountForm } from "mlform";

const mounted = mountForm(container, {
  transport: createJsonTransport({ endpoint: "/api/predict" }),
  schema,
});

Migration map:

Legacy	Current
new MLForm(url)	mountForm(container, { transport: createJsonTransport({ endpoint: url }), schema })
toHTMLElement(...)	mountForm(...)
inputs collection	fields collection
outputs collection	reports collection
field type	field kind
field title	field label
onSubmit callback	hooks.afterSubmit, hooks.beforeSubmit, or mounted.form.submit()
mlform/extensions strategies	engine definitions and primitive registries

Legacy schema:

const oldSchema = {
  inputs: [{ type: "text", title: "Prompt" }],
  outputs: [{ type: "classifier", title: "Prediction" }],
};

Current schema:

const schema = {
  fields: [{ kind: "text", label: "Prompt" }],
  reports: [{ kind: "classifier", label: "Prediction" }],
};

Transport-breaking changes since the early transport helpers:

• transport.capabilities is now normalized:
  • modes
  • safety
  • limits
  • auth
  • delivery
• withMetrics now takes { emit(event) } instead of separate callbacks.
• shared policy stores are scoped:
  • TransportCacheStore.get(scope, key)
  • SharedRateLimiter.acquire(scope, lease)
  • CircuitBreakerSharedState.get(scope)
  • TransportHealthState.getSnapshot(scope, transportId)
• SubmitRequest.metadata.estimatedPayloadBytes is populated when MLForm can estimate payload size.
• session transports should expose session.capabilities.backpressure and may expose bufferedMessages.

Minimal capability migration example:

const transport = {
  async submit(request) {
    return callBackend(request.serializedValues);
  },
  capabilities: {
    modes: { submit: true, stream: false, session: false },
    safety: { idempotent: false, retrySafe: false, cacheable: false, hedgeSafe: false },
    limits: {},
    auth: { kinds: ["none"] },
    delivery: { mode: "request-response", consistency: "unknown", backpressure: "none" },
  },
};