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

# SG-4 — A ForEach node initializes its iterator once and completes on an empty list

*RT-SG (Part II) · level: extended · profiles: runtime · added in 1.0*

## The rule

> **Normative.** This is the rule.
>
> 1. A ForEach node initializes its iterator on the round where the state carries none, and requires items to iterate.
>
> 2. A value that is not a list is wrapped as a single item, and the items are re-indexed so that iteration is positional.
>
> 3. An empty list completes the node immediately rather than entering the loop.
>
> 4. On completion the node emits its defined output set, including the results collected across the rounds it ran.


## What it means

An empty list is not a loop that runs zero times — it is completion on the
first round, with the node's whole defined output set produced immediately,
current item included as absent rather than left unset. A value that is not
a list at all is not refused either: it is wrapped as the one item a single
round iterates, re-indexed the same way any list would be, so a round that
receives a bare scalar behaves exactly like a round over a one-item list.

## Example

```json title="A ForEach launched with no items"
{"items": []}
```

```json title="What it emits on that round" verdict="completed"
{"loop_active": false, "current_item": null, "total_count": 0, "collected_results": []}
```

```json title="A ForEach launched with one scalar, not a list"
{"items": "scalar_value"}
```

```json title="What it emits on that round" verdict="wrapped"
{"current_item": "scalar_value", "current_index": 0, "total_count": 1, "is_first": true, "is_last": true}
```

## Related rules

- Names: SG-5, SG-7
- Referenced by: SG-5

---

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.