---
id: CMP-6
family: RT-CMP
level: core
profiles: [runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/rt-cmp/cmp-6
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# CMP-6 — Which nodes reach the execution graph

*RT-CMP (Part II) · level: core · profiles: runtime · added in 1.0*

A loop head needs a forward entry edge: being reachable by loopback alone is not enough to be scheduled, even though every re-enterable node type carries a loopback port.

## The rule

> **Normative.** This is the rule.
>
> 1. A node is excluded from the execution graph if its type is non-executable, if it is wired only as a tool provider, or if its only incoming edges are loopback edges.
>
> 2. A node with no incoming edges is included, and so is a node with no edges at all.
>
> 3. The exclusions are applied in that precedence.


## What it means

Being wired to something real does not earn a node a place in the execution
graph. A node whose type is marked non-executable is excluded regardless of
what touches it — including an ordinary incoming connection from a node that
does run — because the exclusion is decided from the node's own type before
its wiring is considered at all. The same precedence protects the opposite
case: a node with no edges at all, or none incoming, is included rather than
treated as an orphan to drop.

## Example

A record-only node wired downstream of a node that does run:

```json title="A record-only node with a real incoming connection" verdict="given"
{
  "nodes": [
    { "id": "input", "type": "text_input" },
    { "id": "mynote", "type": "note" }
  ],
  "edges": [{ "source": "input", "target": "mynote" }]
}
```

```json title="What compilation records for it" verdict="excluded"
{ "id": "mynote", "reason": "non_executable" }
```

The upstream node is unaffected — only the record-only one is left out of
the execution graph.

## Related rules

- Names: CMP-5
- Referenced by: CMP-1, CMP-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.