Added template parameter enabledApiProposalsJson.

Added env: EnabledApiProposalsJson: ${{ parameters.enabledApiProposalsJson }} on the PowerShell@2 step.
Script continues to read $env:EnabledApiProposalsJson (safe for JSON with quotes).
publish-extension.yml
Wired it up: enabledApiProposalsJson: $(EnabledApiProposalsJson) when calling the publish template.
This should fully eliminate the PowerShell parser failure you hit while still allowing the --allow-proposed-apis ... list to be applied when present.

Author: bschnurr

build/templates/publish-extension.yml

@@ -239,6 +239,7 @@ jobs:
               azureSubscription: ${{ parameters.azureSubscription }}
               buildPlatforms: ${{ parameters.buildPlatforms }}
               manifestName: ${{ parameters.manifestName }}
+              enabledApiProposalsJson: $(EnabledApiProposalsJson)
               signatureName: ${{ parameters.signatureName }}
               publishFolder: ${{ parameters.publishFolder }}
               preRelease: ${{ parameters.preRelease }}

build/templates/publish.yml

@@ -42,6 +42,9 @@ parameters:
   - name: preRelease
     type: boolean
     default: false
+  - name: enabledApiProposalsJson
+    type: string
+    default: ''
 
 steps:
   # Node & vsce expected to be prepared by parent pipeline; omit local installation.
@@ -68,6 +71,8 @@ steps:
   - ${{ each platform in parameters.buildPlatforms }}:
       - task: PowerShell@2
         displayName: "Publish extension (${{ coalesce(platform.vsceTarget, 'universal') }})"
+        env:
+          EnabledApiProposalsJson: ${{ parameters.enabledApiProposalsJson }}
         inputs:
           targetType: inline
           script: |
@@ -103,8 +108,8 @@ steps:
             # If the extension uses proposed APIs, vsce requires explicitly allowing them.
             # We expect EnabledApiProposalsJson to be set by an earlier step (e.g. publish-extension.yml).
             $allowProposedApisArgs = @()
-            $enabledApiProposalsJson = "$(EnabledApiProposalsJson)"
-            if (-not $enabledApiProposalsJson -or ($enabledApiProposalsJson -match '^\$\(')) {
+            $enabledApiProposalsJson = $env:EnabledApiProposalsJson
+            if ([string]::IsNullOrWhiteSpace($enabledApiProposalsJson)) {
               Write-Host "EnabledApiProposalsJson is not set; publishing without --allow-proposed-apis."
             } else {
               try {
@@ -120,17 +125,17 @@ steps:
               }
             }
 
+            $allowProposedApisDisplay = ($allowProposedApisArgs -join ' ')
+
             if ('${{ parameters.preRelease }}' -eq 'True') {
               Write-Host 'Publishing as pre-release'
-              $allowProposedApisDisplay = ($allowProposedApisArgs -join ' ')
               $displayCmd = "Executing: npx @vscode/vsce@latest publish --pat *** --packagePath $vsixPath --manifestPath $manifestPath --signaturePath $signaturePath"
               if ($allowProposedApisDisplay) { $displayCmd += " $allowProposedApisDisplay" }
               $displayCmd += ' --pre-release'
               Write-Host $displayCmd
               npx @vscode/vsce@latest publish --pat $aadToken --packagePath $vsixPath --manifestPath $manifestPath --signaturePath $signaturePath $allowProposedApisArgs --pre-release
             } else {
               Write-Host 'Publishing as stable release'
-              $allowProposedApisDisplay = ($allowProposedApisArgs -join ' ')
               $displayCmd = "Executing: npx @vscode/vsce@latest publish --pat *** --packagePath $vsixPath --manifestPath $manifestPath --signaturePath $signaturePath"
               if ($allowProposedApisDisplay) { $displayCmd += " $allowProposedApisDisplay" }
               Write-Host $displayCmd