fix: check tcgc compatibility when autoupdating deps

packages/http-client-csharp/eng/scripts/Update-PackageJson.ps1

@@ -93,6 +93,72 @@ function Get-LatestGAVersion {
     }
 }
 
+# Function to check if a dependency version's peer dep on tcgc is satisfied by our tcgcVersion
+function Test-TcgcCompatibility {
+    param(
+        [string]$PackageName,
+        [string]$PackageVersion,
+        [string]$TcgcVersion
+    )
+
+    Write-Host "Checking if $PackageName@$PackageVersion is compatible with tcgc@$TcgcVersion..."
+    $tcgcRange = & npm view "${PackageName}@${PackageVersion}" "peerDependencies.@azure-tools/typespec-client-generator-core" 2>&1
+
+    if ($LASTEXITCODE -ne 0 -or -not $tcgcRange) {
+        Write-Host "  No tcgc peer dependency found, assuming compatible"
+        return $true
+    }
+
+    $tcgcRange = ($tcgcRange | Out-String).Trim()
+    Write-Host "  Requires tcgc: $tcgcRange"
+
+    $jsCode = "try{console.log(require('semver').satisfies('$TcgcVersion','$tcgcRange'))}catch(e){console.log('error')}"
+    $semverResult = (& node -e $jsCode 2>&1 | Out-String).Trim()
+
+    if ($semverResult -eq 'true') {
+        Write-Host "  ✓ Compatible"
+        return $true
+    } else {
+        Write-Host "  ✗ Not compatible"
+        return $false
+    }
+}
+
+# Function to get previous GA versions of a package sorted descending, before a given version
+function Get-PreviousGAVersions {
+    param(
+        [string]$PackageName,
+        [string]$BeforeVersion
+    )
+
+    Write-Host "Getting previous GA versions of $PackageName (before $BeforeVersion)..."
+    $result = & npm view $PackageName versions --json 2>&1
+
+    if ($LASTEXITCODE -ne 0) {
+        Write-Warning "Could not retrieve versions for $PackageName"
+        return @()
+    }
+
+    $allVersions = ($result | Out-String) | ConvertFrom-Json
+
+    if ($allVersions -isnot [array]) {
+        $allVersions = @($allVersions)
+    }
+
+    # Filter to GA only (no prerelease) and versions strictly less than BeforeVersion
+    $gaVersions = @($allVersions | Where-Object {
+        $_ -notmatch '-' -and ([version]$_ -lt [version]$BeforeVersion)
+    } | Sort-Object { [version]$_ } -Descending)
+
+    if ($gaVersions.Count -gt 0) {
+        Write-Host "  Found $($gaVersions.Count) previous GA version(s), most recent: $($gaVersions[0])"
+    } else {
+        Write-Host "  No previous GA versions found"
+    }
+
+    return $gaVersions
+}
+
 # Resolve paths
 $PackageJsonPath = Resolve-Path $PackageJsonPath
 
@@ -140,29 +206,53 @@ try {
     $dependencyVersions = @{}
 
     foreach ($dependency in $InjectedDependencies) {
-        $versionToUse = $tcgcVersion
+        $versionToUse = $null
 
-        # Check if the tcgc version exists for this dependency
-        if (-not (Test-PackageVersion -PackageName $dependency -Version $tcgcVersion)) {
-            Write-Warning "Version $tcgcVersion not found for $dependency"
-
-            # Use the version from tcgc's @azure-tools/typespec-azure-core dependency as fallback
-            if ($fallbackVersion -and (Test-PackageVersion -PackageName $dependency -Version $fallbackVersion)) {
+        # 1. Try the tcgc version if it exists and is compatible with our tcgc
+        if ((Test-PackageVersion -PackageName $dependency -Version $tcgcVersion) -and
+            (Test-TcgcCompatibility -PackageName $dependency -PackageVersion $tcgcVersion -TcgcVersion $tcgcVersion)) {
+            $versionToUse = $tcgcVersion
+        }
+
+        # 2. Search up to 2 previous GA versions for one compatible with our tcgc
+        if (-not $versionToUse) {
+            Write-Host "Searching previous GA versions of $dependency compatible with tcgc@$tcgcVersion..."
+            $previousVersions = Get-PreviousGAVersions -PackageName $dependency -BeforeVersion $tcgcVersion
+            $attempts = 0
+            foreach ($prevVersion in $previousVersions) {
+                if ($attempts -ge 2) { break }
+                $attempts++
+
+                if (Test-TcgcCompatibility -PackageName $dependency -PackageVersion $prevVersion -TcgcVersion $tcgcVersion) {
+                    $versionToUse = $prevVersion
+                    Write-Host "Found compatible previous version: $dependency@$prevVersion"
+                    break
+                }
+            }
+        }
+
+        # 3. Fallback: use the version from tcgc's azure-core dependency
+        if (-not $versionToUse -and $fallbackVersion) {
+            if (Test-PackageVersion -PackageName $dependency -Version $fallbackVersion) {
                 Write-Host "Using fallback version $fallbackVersion for $dependency"
                 $versionToUse = $fallbackVersion
-            } else {
-                # Final fallback: use the latest GA version of the package
-                $latestGA = Get-LatestGAVersion -PackageName $dependency
-                if ($latestGA) {
-                    Write-Host "Using latest GA version $latestGA for $dependency"
-                    $versionToUse = $latestGA
-                } else {
-                    Write-Error "Could not determine a valid version for $dependency (no fallback available)"
-                    exit 1
-                }
             }
         }
 
+        # 4. Final fallback: latest GA version
+        if (-not $versionToUse) {
+            $latestGA = Get-LatestGAVersion -PackageName $dependency
+            if ($latestGA) {
+                Write-Host "Using latest GA version $latestGA for $dependency"
+                $versionToUse = $latestGA
+            }
+        }
+
+        if (-not $versionToUse) {
+            Write-Error "Could not determine a valid version for $dependency (no fallback available)"
+            exit 1
+        }
+
         # Store the version to use for this dependency
         $dependencyVersions[$dependency] = $versionToUse