---
id: R4.d
family: GR-VAL
level: core
profiles: [storage-api]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-val/r4-d
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# R4.d — An exposure entry must name a port the node declares

*GR-VAL (Part I) · level: core · profiles: storage-api · added in 1.0*

## The rule

> **Normative.** This is the rule.
>
> 1. A workflow exposure entry's `port` must be declared by the named node: as an input parameter for an entry on the input side, as an output for one on the output side.
>
> 2. An entry naming an undeclared port is refused at `schema.{side}.{index}`.
>
> 3. Where the node's executor cannot be resolved the port cannot be checked, so this check and R10 are skipped for that entry rather than guessed at; the skip is narrower than the entry, and R4.a's name format and R4.b's uniqueness (both decided from the entry alone) are still reported.


## What it means

The skip this rule allows is narrower than it sounds. Losing the ability to
resolve a node's declared ports only silences this one check and R10; it does
not silence R4.a's name-format check or R4.b's uniqueness check, both of which
are decided from the entry's own fields and need nothing from the node. An
entry can therefore fail on its name at the same time its port check is
skipped for want of a resolvable node — one refusal, not a cascade of
guesses about a port that was never checked.

## Example

An exposure entry naming an unresolvable node, with a name that also fails
the format check:

```json title="An exposure entry on a node whose executor can't be resolved" verdict="checked"
{ "name": "Bad Name", "node_id": "n1", "port": "no_such_port" }
```

```json title="The two errors reported for that entry" verdict="reported"
["R1_PLUGIN_MISSING", "R4_NAME_FORMAT"]
```

`R4_PORT_MISSING` does not appear: with no resolvable executor there is no
port list to check the entry's `port` against, so this check stays silent
while the name-format complaint still reaches the caller.

## Related rules

- Names: R4.a, R4.b, R10
- Referenced by: R4.c, R10

---

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.