Function initWebMcpForm

packages/forms/signals/src/webmcp/registration.ts:36–80

(
  formTree: FieldTree<unknown>,
  options: {name: string; description: string},
  injector: Injector,
)

};

function initWebMcpForm(
  formTree: FieldTree<unknown>,
  options: {name: string; description: string},
  injector: Injector,
) {
  const node = formTree() as FieldNode;
  const inputSchema = inferSchemaFromFieldNode(node);

  if (!inputSchema) {
    throw new Error(
      `Could not accurately infer WebMCP schema for form "${options.name}". ` +
        `Ensure that the form model does not contain null, undefined, empty arrays, or unsupported types.`,
    );
  }

  declareExperimentalWebMcpTool(
    {
      name: options.name,
      description: options.description,
      inputSchema,
      execute: async (args: Record<string, unknown>) => {
        // Populate the form with changes from the agent.
        node.value.set(args);

        // Trigger form submission.
        const success = await submit(formTree);

        // Report the result to the agent.
        if (success) {
          return {content: [{type: 'text', text: 'Form submitted successfully.'}]};
        } else {
          const errorMessages = node
            .errorSummary()
            .map((err) => {
              const fieldName = (err.fieldTree() as FieldNode).structure.pathKeys().join('.');
              return `${fieldName ? `${fieldName}: ` : ''}${err.message || err.kind}`;
            })
            .join('\n');
          return {content: [{type: 'text', text: `Form submission failed:\n${errorMessages}`}]};
        }
      },
    },
    injector,
  );
}

/** Infers the JSON schema from a specific form field. */
function inferSchemaFromFieldNode(node: FieldNode): JsonSchemaForInference | undefined {