---
id: SCH-32
family: GR-SCHEMA
level: extended
profiles: [storage-api, editor-client]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-schema/sch-32
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# SCH-32 — Every re-enterable node gets a hidden loop-back input

*GR-SCHEMA (Part I) · level: extended · profiles: storage-api, editor-client · added in 1.0*

Re-entry is a property of the graph, not of a handful of node types. Every node that can be re-entered declares the port; it just ships hidden, so no canvas gains a re-entry handle until an author asks for one.

## The rule

> **Normative.** This is the rule.
>
> 1. A reserved `loop_back` input is injected on every re-enterable node type (every node type that is not a start, terminal or non-executable one) with display order 95 and the `trigger` lane, and it ships hidden, so no canvas gains a re-entry handle until an author exposes the port on that instance.
>
> 2. A node type that declares its own `loop_back` keeps it and the injection is skipped, because such a declaration carries semantics the injection does not.
>
> 3. Because the port is now declared rather than absent, an edge drawn into an unexposed `loop_back` is refused as an edge into an unexposed port, where previously it fell outside the check entirely.


## What it means

The injected port ships hidden by default, so declaring re-entry legal on
every eligible node type does not put a re-entry handle in every editor —
an author still has to expose it per instance before a wire can land there.
Where a node type already declares its own `loop_back`, the injection does
not run at all: the declared port is kept as-is, not merged with or replaced
by the injected one.

## Example

```json title="exposedByDefault of the loop_back input injected on an ordinary node type" verdict="hidden"
false
```

```json title="The name of the only loop_back input on a node type that declares its own" verdict="kept"
"Custom Loop Back"
```

## Related rules

- Names: SCH-16, SCH-37, SCH-38
- Referenced by: SCH-16, SCH-33, SCH-38

---

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.