Enterprise integration. Reinvented in Markdown.

## Step: check-booking
```validate
$.shipmentId != null    | "shipmentId is required"                    | syntactic
$.hubCode != null       | "hubCode is required"                       | syntactic
$.parcelCount > 0       | "parcelCount must be greater than zero"
$.weightKg > 0          | "weightKg must be greater than zero"
```

…

## Step: acknowledge
response_status: 202
```ntd
{
  "status": "ACCEPTED",
  "shipmentId": "{{ $.echo.shipmentId }}",
  "waybill": "{{ $.echo.waybill }}",
  "hubCode": "{{ $.echo.hubCode }}",
  "parcelCount": {{ $.echo.parcelCount }}
}
```

$ nexus validate flows/01-shipment-intake.flow.md
ok  flows/01-shipment-intake.flow.md
    flow:   shipment-intake
    tenant: meridian
    steps:  3

---
flowmarkdown_version: 0.1
flow: p10-xslt-necoborabil
tenant: acme
effects: []
---
## Step: x
```xslt
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <xsl:apply-templates select="*"/>
  </xsl:template>
  <xsl:template match="*">
    <copiat><xsl:value-of select="."/></copiat>
  </xsl:template>
</xsl:stylesheet>
```

$ nexus validate flows/p10-xslt-necoborabil.flow.md
error: step 'x': this XSLT sheet is outside the subset this platform compiles, and there is no XSLT engine at run time — unsupported XSLT construct <xsl:apply-templates>: recursive template application requires a runtime XSLT engine. Rewrite the step as `ntd`: it expresses the same transformations, and its failures are visible here rather than at the first message. `descendants()` covers `//name` searches, `string()` takes an element's text, and `{{ if }}` / `{{ for }}` cover `xsl:choose` and `xsl:for-each`
error: 1 validation error(s)