Validation reason is not displayed when adapter validate operation fails

[Gijsreyn]

Prerequisites

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Summary

When an adapter resource's validate operation returns valid: false with a custom reason field, DSC ignores the reason and only displays a generic error message.

Steps to reproduce

Build a simple adapter and add the reason field:

'Validate' {
        # Parse input JSON to validate structure
        if ($null -eq $inputObj.resources.properties.path) {
            @{ 
                valid = $false
                reason = "Missing required property 'path'"
            } | ConvertTo-Json -Compress
        }
        else {
            @{ valid = $true } | ConvertTo-Json -Compress
        }
    }

Expected behavior

Validation: Missing required property 'path' if `path` is not provided.

Actual behavior

Validation: Resource reported input JSON is not valid

Error details

Environment data

Name                           Value
----                           -----
PSVersion                      7.5.4
PSEdition                      Core
GitCommitId                    7.5.4
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

dsc 3.2.0-preview.10

Visuals

No response

[SteveL-MSFT]

Would like to have WG discuss the proposed design