Removed extension attribute requirement for testing

src/DataProviders/Invoke-PersonaGraphRequest.ps1

@@ -149,6 +149,42 @@ function Get-PersonaGraphStatusCode {
     return $null
 }
 
+function Test-PersonaTargetAttributeUnavailable {
+    <#
+    .SYNOPSIS
+        True when a Graph 400 means the target attribute does not exist in this
+        tenant, rather than some other client error.
+
+    .DESCRIPTION
+        A dev tenant with no app registration has no persona extension property.
+        Requesting it in $select then fails with 400 and a message naming the
+        property. This distinguishes that specific, recoverable case from every
+        other 400 (bad query syntax, an unrelated bad property, a permission denial
+        phrased as 400), which must still fail loudly rather than being swallowed.
+
+    .PARAMETER ErrorRecord
+        The error caught from Invoke-PersonaGraphRequest.
+
+    .PARAMETER TargetAttribute
+        The configured target attribute name.
+    #>
+    [CmdletBinding()]
+    [OutputType([bool])]
+    param(
+        [Parameter(Mandatory)] $ErrorRecord,
+        [Parameter(Mandatory)] [string] $TargetAttribute
+    )
+
+    if ((Get-PersonaGraphStatusCode -ErrorRecord $ErrorRecord) -ne 400) { return $false }
+
+    $text = @($ErrorRecord.Exception.Message, $ErrorRecord.ErrorDetails.Message) -join ' '
+    if ([string]::IsNullOrWhiteSpace($text)) { return $false }
+
+    if ($text -notmatch [regex]::Escape($TargetAttribute)) { return $false }
+
+    [bool]($text -match '(?i)could not find a property|invalid property|is not a valid property|does not exist on type')
+}
+
 function Get-PersonaRetryAfterMs {
     <#
     .SYNOPSIS

src/Engine/Invoke-PersonaEngineRun.ps1

@@ -98,9 +98,32 @@ function Invoke-PersonaEngineRun {
             : @(Get-PersonaUsers -SelectProperties $selectProperties)
     }
     catch {
-        # A partial population is worse than none: half a tenant classified looks
-        # like a successful run to everything downstream.
-        return New-PersonaRunOutcome -Counters $counters -ExitCode $EXIT_ENUMERATION -FailureReason $_.Exception.Message
+        if ((-not $IsEnforcing) -and (Test-PersonaTargetAttributeUnavailable -ErrorRecord $_ -TargetAttribute $TargetAttribute)) {
+            # Dev/test tenants often have no app registration yet, so the persona
+            # extension property was never created. Preview mode never writes
+            # regardless of what StoredPersona holds, so treating the attribute as
+            # absent (null) here is safe and lets development proceed without one.
+            # Enforcement still fails loudly - IsEnforcing gates this precisely
+            # because writing to an attribute that does not exist must never be
+            # silently tolerated.
+            Write-Warning "Target attribute '$TargetAttribute' was not found in this tenant (no app registration / extension property?). Continuing in What-If mode with it treated as null for every account."
+
+            $fallbackProperties = @($selectProperties | Where-Object { $_ -cne $TargetAttribute })
+
+            try {
+                $users = $UserObjectId `
+                    ? @(Get-PersonaUsers -SelectProperties $fallbackProperties -UserObjectId $UserObjectId) `
+                    : @(Get-PersonaUsers -SelectProperties $fallbackProperties)
+            }
+            catch {
+                return New-PersonaRunOutcome -Counters $counters -ExitCode $EXIT_ENUMERATION -FailureReason $_.Exception.Message
+            }
+        }
+        else {
+            # A partial population is worse than none: half a tenant classified looks
+            # like a successful run to everything downstream.
+            return New-PersonaRunOutcome -Counters $counters -ExitCode $EXIT_ENUMERATION -FailureReason $_.Exception.Message
+        }
     }
 
     foreach ($graphUser in $users) {