---
id: META-4
family: RT-META
level: core
profiles: [runtime, editor-client]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/rt-meta/meta-4
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# META-4 — The workflow schema door publishes a bare document

*RT-META (Part II) · level: core · profiles: runtime, editor-client · added in 1.0*

A workflow's declared input and output ports, read by an editor before it can draw the workflow. It is not wrapped in the standard envelope, and its snake_case is as much a contract as the playground's camelCase.

## The rule

> **Normative.** This is the rule.
>
> 1. A successful read of a workflow's schema answers exactly `{schema_version, parameter_schema, output_schema}` in that order, snake_case, with no `success` key and no `data` wrapper.
>
> 2. `parameter_schema` and `output_schema` are the stored snapshot verbatim, and where a workflow declares no ports they are JSON `null` (not an empty object, and not omitted), so a consumer can distinguish "no ports" from "key missing".


## What it means

This door answers with no envelope at all: no `success`, no `data`, just the
three keys themselves. And where a workflow declares no ports, the missing
schema is `null`, not an empty object and not a key left out — the three
shapes ("no ports", "an empty object", "key missing") would otherwise all
look the same to a consumer that has to guess which one it is looking at.

## Example

A workflow with both a declared input and a declared output:

```http title="A workflow's declared parameter and output schemas" verdict="200 served"
GET /api/flowdrop/workflows/{id}/schema

{"schema_version": "2.1.0", "parameter_schema": {"type": "object", "properties": {"name": {"type": "string"}}}, "output_schema": {"type": "object", "properties": {"result": {"type": "string"}}}}
```

A workflow that declares no ports at all:

```http title="A workflow with no declared ports" verdict="200 served"
GET /api/flowdrop/workflows/{id}/schema

{"schema_version": "0.0.0", "parameter_schema": null, "output_schema": null}
```

## Related rules

- Names: META-5, META-6
- Referenced by: META-5, META-6, META-9, STORE-8

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.