DF0044: Invalid RPC Return Value

Message

RPC function "{name}" returned a value that failed its returns schema: {issues}

Cause

When an RPC function declares a returns schema, the handler's resolved value is validated against that Standard Schema (valibot, zod, arktype, …) before it is sent back to the caller. The value the handler produced does not satisfy the schema — a bug in the handler or a schema that is narrower than the real result. Validation guards the payload without rewriting it, so a value that merely carries extra object fields is accepted.

Example

const count = defineRpcFunction({
  name: 'count',
  args: [],
  returns: v.number(),
  // ✗ Bad — returns a string where a number is declared → DF0044
  handler: () => 'twelve' as never,
})

Fix

Make the handler return a value that satisfies the returns schema, or relax the schema so it describes the value the handler actually produces.

Source

• packages/devframe/src/rpc/validate-io.ts — validateRpcReturn() throws DF0044 when the handler's resolved value fails its declared schema.