fix: add Monaco/Puppeteer terms to spell-check allow list

Agent-Logs-Url: https://github.com/microsoft/PowerToys/sessions/755156df-f3b9-43b8-b696-94b18a48c257

Co-authored-by: crutkas <1462282+crutkas@users.noreply.github.com>

.github/actions/spell-check/allow/code.txt

@@ -367,3 +367,14 @@ Nonpaged
 
 # XAML
 Untargeted
+
+# Monaco Editor / Puppeteer
+cdp
+Cdp
+crdownload
+networkidle
+
+# Monaco Editor languages
+kotlin
+ksh
+pde

.github/scripts/generate-monaco-languages.js

@@ -0,0 +1,230 @@
+/**
+ * generate-monaco-languages.js
+ *
+ * Generates monaco_languages.json using Puppeteer to run the existing
+ * generateLanguagesJson.html in a headless browser. This exactly mirrors
+ * the manual process described in doc/devdocs/common/FilePreviewCommon.md.
+ *
+ * Usage: node generate-monaco-languages.js <path-to-src/Monaco>
+ */
+
+"use strict";
+
+const path = require("path");
+const fs = require("fs");
+const http = require("http");
+
+const monacoDir = process.argv[2];
+if (!monacoDir) {
+  console.error("Usage: node generate-monaco-languages.js <monaco-dir>");
+  process.exit(1);
+}
+
+const absMonacoDir = path.resolve(monacoDir);
+const outputPath = path.join(absMonacoDir, "monaco_languages.json");
+const htmlPath = path.join(absMonacoDir, "generateLanguagesJson.html");
+
+if (!fs.existsSync(htmlPath)) {
+  console.error(`generateLanguagesJson.html not found at: ${htmlPath}`);
+  process.exit(1);
+}
+
+async function main() {
+  let server;
+  let browser;
+
+  try {
+    // Step 1: Start a local HTTP server serving the Monaco directory.
+    // The generateLanguagesJson.html must be served over HTTP because
+    // browsers block ES module imports and AMD require from file:// URLs.
+    server = await startServer(absMonacoDir);
+    const port = server.address().port;
+    console.log(`Local server started on port ${port}`);
+
+    // Step 2: Launch headless browser via Puppeteer
+    const puppeteer = require("puppeteer");
+    browser = await puppeteer.launch({
+      headless: true,
+      args: ["--no-sandbox", "--disable-setuid-sandbox"],
+    });
+
+    const page = await browser.newPage();
+
+    // Step 3: Set up download interception.
+    // generateLanguagesJson.html creates an <a> element and clicks it to
+    // trigger a download of monaco_languages.json. We intercept this
+    // using CDP to redirect downloads to a temp directory.
+    const downloadDir = path.join(
+      absMonacoDir,
+      ".monaco-download-tmp"
+    );
+    fs.mkdirSync(downloadDir, { recursive: true });
+
+    try {
+      const cdp = await browser.target().createCDPSession();
+      await cdp.send("Browser.setDownloadBehavior", {
+        behavior: "allow",
+        downloadPath: downloadDir,
+      });
+
+      const pageCdp = await page.createCDPSession();
+      await pageCdp.send("Page.setDownloadBehavior", {
+        behavior: "allow",
+        downloadPath: downloadDir,
+      });
+    } catch (err) {
+      throw new Error(
+        `Failed to configure download behavior via CDP: ${err.message}`
+      );
+    }
+
+    // Step 4: Navigate to the generator page.
+    // The page auto-loads Monaco, registers custom languages, calls
+    // getLanguages(), and triggers a download of the JSON.
+    console.log("Navigating to generateLanguagesJson.html...");
+    await page.goto(`http://localhost:${port}/generateLanguagesJson.html`, {
+      waitUntil: "networkidle0",
+      timeout: 60000,
+    });
+
+    // Step 5: Wait for the download to complete.
+    const downloadedFile = await waitForDownload(
+      downloadDir,
+      "monaco_languages.json",
+      30000
+    );
+
+    // Step 6: Move the downloaded file to the target location.
+    const downloadedContent = fs.readFileSync(downloadedFile, "utf-8");
+
+    // Validate the content is valid JSON before writing
+    const parsed = JSON.parse(downloadedContent);
+    if (!parsed.list || !Array.isArray(parsed.list)) {
+      throw new Error(
+        "Downloaded JSON does not have the expected { list: [...] } structure"
+      );
+    }
+
+    fs.writeFileSync(outputPath, downloadedContent, "utf-8");
+    console.log(
+      `monaco_languages.json written with ${parsed.list.length} languages.`
+    );
+  } catch (err) {
+    console.error("Failed to generate monaco_languages.json:", err.message);
+    process.exit(1);
+  } finally {
+    if (browser) {
+      await browser.close().catch(() => {});
+    }
+    if (server) {
+      server.close();
+    }
+    // Clean up temp download directory AFTER browser is closed
+    const downloadDir = path.join(absMonacoDir, ".monaco-download-tmp");
+    if (fs.existsSync(downloadDir)) {
+      fs.rmSync(downloadDir, { recursive: true, force: true });
+    }
+  }
+}
+
+/**
+ * Starts a simple HTTP server that serves static files from the given
+ * directory. Supports .js, .html, .css, .json, .ttf MIME types.
+ */
+function startServer(rootDir) {
+  return new Promise((resolve, reject) => {
+    const mimeTypes = {
+      ".html": "text/html",
+      ".js": "application/javascript",
+      ".mjs": "application/javascript",
+      ".css": "text/css",
+      ".json": "application/json",
+      ".ttf": "font/ttf",
+      ".woff": "font/woff",
+      ".woff2": "font/woff2",
+      ".svg": "image/svg+xml",
+      ".png": "image/png",
+    };
+
+    const server = http.createServer((req, res) => {
+      const urlPath = decodeURIComponent(req.url.split("?")[0]);
+      const filePath = path.join(rootDir, urlPath);
+
+      // Security: ensure we don't serve files outside rootDir
+      const resolvedRoot = path.resolve(rootDir);
+      const resolvedPath = path.resolve(rootDir, urlPath);
+      if (
+        resolvedPath !== resolvedRoot &&
+        !resolvedPath.startsWith(resolvedRoot + path.sep)
+      ) {
+        res.writeHead(403);
+        res.end("Forbidden");
+        return;
+      }
+
+      if (!fs.existsSync(resolvedPath) || fs.statSync(resolvedPath).isDirectory()) {
+        res.writeHead(404);
+        res.end("Not Found");
+        return;
+      }
+
+      const ext = path.extname(resolvedPath).toLowerCase();
+      const contentType = mimeTypes[ext] || "application/octet-stream";
+
+      const content = fs.readFileSync(resolvedPath);
+      res.writeHead(200, { "Content-Type": contentType });
+      res.end(content);
+    });
+
+    server.listen(0, "127.0.0.1", () => {
+      resolve(server);
+    });
+
+    server.on("error", reject);
+  });
+}
+
+/**
+ * Waits for a file to appear in the download directory.
+ * Puppeteer downloads may have a .crdownload suffix while in progress.
+ */
+function waitForDownload(downloadDir, expectedFilename, timeoutMs) {
+  return new Promise((resolve, reject) => {
+    const startTime = Date.now();
+
+    const check = () => {
+      const files = fs.readdirSync(downloadDir);
+
+      // Check for the expected file (not a .crdownload partial)
+      const targetFile = files.find(
+        (f) => f === expectedFilename && !f.endsWith(".crdownload")
+      );
+
+      if (targetFile) {
+        const filePath = path.join(downloadDir, targetFile);
+        // Ensure file has content (not still being written)
+        const stat = fs.statSync(filePath);
+        if (stat.size > 0) {
+          resolve(filePath);
+          return;
+        }
+      }
+
+      if (Date.now() - startTime > timeoutMs) {
+        reject(
+          new Error(
+            `Timed out waiting for ${expectedFilename} download after ${timeoutMs}ms. ` +
+              `Files in download dir: ${files.join(", ") || "(empty)"}`
+          )
+        );
+        return;
+      }
+
+      setTimeout(check, 500);
+    };
+
+    check();
+  });
+}
+
+main();

.github/scripts/tests/validate-monaco-update.tests.ps1

@@ -0,0 +1,371 @@
+<#
+.SYNOPSIS
+    Validates that a Monaco Editor update was performed correctly.
+
+.DESCRIPTION
+    Runs a series of checks against the Monaco Editor files in the repository
+    to ensure the update is valid and no regressions were introduced.
+
+    Tests:
+      - loader.js exists and contains version info
+      - monaco_languages.json is valid JSON with expected structure
+      - All expected built-in Monaco languages are present
+      - All PowerToys custom languages are registered
+      - Custom language extension mappings are present
+      - Monaco directory structure is intact
+      - No empty/corrupt core files
+      - Version consistency across Monaco files
+
+.PARAMETER RepoRoot
+    The root of the PowerToys repository. Defaults to the repo root
+    relative to this script.
+
+.EXAMPLE
+    ./validate-monaco-update.tests.ps1
+    ./validate-monaco-update.tests.ps1 -RepoRoot "C:\src\PowerToys"
+#>
+[CmdletBinding()]
+param(
+    [Parameter()]
+    [string]$RepoRoot
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+if (-not $RepoRoot) {
+    $RepoRoot = (Resolve-Path (Join-Path $PSScriptRoot ".." ".." "..")).Path
+}
+
+$monacoDir = Join-Path $RepoRoot "src" "Monaco"
+$monacoSrcDir = Join-Path $monacoDir "monacoSRC"
+$minDir = Join-Path $monacoSrcDir "min"
+$loaderJsPath = Join-Path $minDir "vs" "loader.js"
+$languagesJsonPath = Join-Path $monacoDir "monaco_languages.json"
+$customLangsDir = Join-Path $monacoDir "customLanguages"
+
+$testsPassed = 0
+$testsFailed = 0
+$testResults = @()
+
+function Assert-Test {
+    param(
+        [string]$Name,
+        [scriptblock]$Test
+    )
+
+    try {
+        $result = & $Test
+        if ($result -eq $false) {
+            throw "Assertion returned false"
+        }
+        $script:testsPassed++
+        $script:testResults += [PSCustomObject]@{ Name = $Name; Status = "PASS"; Error = $null }
+        Write-Host "  [PASS] $Name" -ForegroundColor Green
+    }
+    catch {
+        $script:testsFailed++
+        $script:testResults += [PSCustomObject]@{ Name = $Name; Status = "FAIL"; Error = $_.Exception.Message }
+        Write-Host "  [FAIL] $Name" -ForegroundColor Red
+        Write-Host "         $($_.Exception.Message)" -ForegroundColor Red
+    }
+}
+
+Write-Host "=== Monaco Editor Update Validation ===" -ForegroundColor Cyan
+Write-Host "Repository root: $RepoRoot"
+Write-Host ""
+
+# ─── Test Group 1: Directory Structure ────────────────────────────────
+Write-Host "--- Directory Structure ---" -ForegroundColor Yellow
+
+Assert-Test "Monaco directory exists" {
+    Test-Path $monacoDir
+}
+
+Assert-Test "monacoSRC directory exists" {
+    Test-Path $monacoSrcDir
+}
+
+Assert-Test "min directory exists" {
+    Test-Path $minDir
+}
+
+Assert-Test "vs subdirectory exists" {
+    Test-Path (Join-Path $minDir "vs")
+}
+
+Assert-Test "editor directory exists" {
+    Test-Path (Join-Path $minDir "vs" "editor")
+}
+
+Assert-Test "basic-languages directory exists" {
+    Test-Path (Join-Path $minDir "vs" "basic-languages")
+}
+
+Assert-Test "base directory exists" {
+    Test-Path (Join-Path $minDir "vs" "base")
+}
+
+Assert-Test "language directory exists" {
+    Test-Path (Join-Path $minDir "vs" "language")
+}
+
+Assert-Test "customLanguages directory exists" {
+    Test-Path $customLangsDir
+}
+
+# ─── Test Group 2: Core Files ─────────────────────────────────────────
+Write-Host "`n--- Core Files ---" -ForegroundColor Yellow
+
+Assert-Test "loader.js exists" {
+    Test-Path $loaderJsPath
+}
+
+Assert-Test "loader.js is not empty" {
+    (Get-Item $loaderJsPath).Length -gt 0
+}
+
+Assert-Test "loader.js contains version string" {
+    $content = Get-Content $loaderJsPath -Raw
+    $content -match 'Version:\s*\d+\.\d+\.\d+'
+}
+
+Assert-Test "editor.main.js exists" {
+    Test-Path (Join-Path $minDir "vs" "editor" "editor.main.js")
+}
+
+Assert-Test "editor.main.js is not empty" {
+    (Get-Item (Join-Path $minDir "vs" "editor" "editor.main.js")).Length -gt 0
+}
+
+Assert-Test "editor.main.css exists" {
+    Test-Path (Join-Path $minDir "vs" "editor" "editor.main.css")
+}
+
+Assert-Test "monacoSpecialLanguages.js exists" {
+    Test-Path (Join-Path $monacoDir "monacoSpecialLanguages.js")
+}
+
+Assert-Test "generateLanguagesJson.html exists" {
+    Test-Path (Join-Path $monacoDir "generateLanguagesJson.html")
+}
+
+Assert-Test "index.html exists" {
+    Test-Path (Join-Path $monacoDir "index.html")
+}
+
+Assert-Test "customTokenThemeRules.js exists" {
+    Test-Path (Join-Path $monacoDir "customTokenThemeRules.js")
+}
+
+# ─── Test Group 3: monaco_languages.json ──────────────────────────────
+Write-Host "`n--- monaco_languages.json ---" -ForegroundColor Yellow
+
+Assert-Test "monaco_languages.json exists" {
+    Test-Path $languagesJsonPath
+}
+
+Assert-Test "monaco_languages.json is not empty" {
+    (Get-Item $languagesJsonPath).Length -gt 0
+}
+
+$languagesJson = $null
+Assert-Test "monaco_languages.json is valid JSON" {
+    $script:languagesJson = Get-Content $languagesJsonPath -Raw | ConvertFrom-Json
+    $null -ne $script:languagesJson
+}
+
+Assert-Test "JSON has 'list' property" {
+    $null -ne $languagesJson.list
+}
+
+Assert-Test "Language list is a non-empty array" {
+    $languagesJson.list.Count -gt 0
+}
+
+Assert-Test "Minimum language count check (at least 80 languages)" {
+    $languagesJson.list.Count -ge 80
+}
+
+# Core built-in languages that should always be present
+$expectedBuiltinLanguages = @(
+    "plaintext", "javascript", "typescript", "html", "css", "json",
+    "xml", "markdown", "yaml", "python", "java", "csharp", "cpp",
+    "go", "rust", "ruby", "php", "sql", "shell", "powershell",
+    "dockerfile", "bat", "fsharp", "lua", "r", "swift", "kotlin",
+    "scala", "perl", "dart", "ini", "vb"
+)
+
+$languageIds = $languagesJson.list | ForEach-Object { $_.id }
+
+foreach ($lang in $expectedBuiltinLanguages) {
+    Assert-Test "Built-in language '$lang' is present" {
+        $lang -in $languageIds
+    }
+}
+
+# ─── Test Group 4: PowerToys Custom Languages ─────────────────────────
+Write-Host "`n--- PowerToys Custom Languages ---" -ForegroundColor Yellow
+
+$expectedCustomLanguages = @(
+    @{ Id = "reg"; Extensions = @(".reg") },
+    @{ Id = "gitignore"; Extensions = @(".gitignore") },
+    @{ Id = "srt"; Extensions = @(".srt") }
+)
+
+foreach ($custom in $expectedCustomLanguages) {
+    Assert-Test "Custom language '$($custom.Id)' is registered" {
+        $custom.Id -in $languageIds
+    }
+
+    foreach ($ext in $custom.Extensions) {
+        Assert-Test "Custom language '$($custom.Id)' has extension '$ext'" {
+            $lang = $languagesJson.list | Where-Object { $_.id -eq $custom.Id }
+            if ($null -eq $lang) { throw "Language not found" }
+            $ext -in $lang.extensions
+        }
+    }
+}
+
+# Custom language definition files exist
+$expectedCustomFiles = @("reg.js", "gitignore.js", "srt.js")
+foreach ($file in $expectedCustomFiles) {
+    Assert-Test "Custom language file '$file' exists" {
+        Test-Path (Join-Path $customLangsDir $file)
+    }
+}
+
+# ─── Test Group 5: Custom Language Extensions ─────────────────────────
+Write-Host "`n--- Custom Language Extensions ---" -ForegroundColor Yellow
+
+$expectedExtensions = @(
+    @{ Id = "cppExt"; Extensions = @(".ino", ".pde") },
+    @{ Id = "xmlExt"; Extensions = @(".wsdl", ".csproj", ".vcxproj", ".vbproj", ".fsproj", ".resx", ".resw") },
+    @{ Id = "txtExt"; Extensions = @(".sln", ".log") },
+    @{ Id = "razorExt"; Extensions = @(".razor") },
+    @{ Id = "vbExt"; Extensions = @(".vbs") },
+    @{ Id = "iniExt"; Extensions = @(".inf") },
+    @{ Id = "shellExt"; Extensions = @(".ksh", ".zsh", ".bsh") }
+)
+
+foreach ($ext in $expectedExtensions) {
+    Assert-Test "Extension mapping '$($ext.Id)' is registered" {
+        $ext.Id -in $languageIds
+    }
+
+    # Check all extensions from each mapping
+    foreach ($extension in $ext.Extensions) {
+        Assert-Test "Extension mapping '$($ext.Id)' has extension '$extension'" {
+            $lang = $languagesJson.list | Where-Object { $_.id -eq $ext.Id }
+            if ($null -eq $lang) { throw "Language not found" }
+            $extension -in $lang.extensions
+        }
+    }
+}
+
+# ─── Test Group 6: Language Entry Structure ───────────────────────────
+Write-Host "`n--- Language Entry Structure ---" -ForegroundColor Yellow
+
+Assert-Test "Every language has an 'id' field" {
+    $missing = @($languagesJson.list | Where-Object { -not $_.id -or $_.id.Trim() -eq "" })
+    $missing.Count -eq 0
+}
+
+Assert-Test "No duplicate language IDs" {
+    $ids = $languagesJson.list | ForEach-Object { $_.id }
+    $uniqueIds = $ids | Select-Object -Unique
+    $ids.Count -eq $uniqueIds.Count
+}
+
+Assert-Test "Languages with extensions have array-type extensions" {
+    $withExtensions = @($languagesJson.list | Where-Object {
+        ($_.PSObject.Properties.Name -contains "extensions") -and ($null -ne $_.extensions)
+    })
+    $invalid = @($withExtensions | Where-Object { $_.extensions -isnot [array] })
+    $invalid.Count -eq 0
+}
+
+# Spot-check known extension-to-language mappings
+$extensionMappings = @(
+    @{ Extension = ".js"; ExpectedLanguage = "javascript" },
+    @{ Extension = ".py"; ExpectedLanguage = "python" },
+    @{ Extension = ".cs"; ExpectedLanguage = "csharp" },
+    @{ Extension = ".html"; ExpectedLanguage = "html" },
+    @{ Extension = ".css"; ExpectedLanguage = "css" },
+    @{ Extension = ".json"; ExpectedLanguage = "json" },
+    @{ Extension = ".ts"; ExpectedLanguage = "typescript" },
+    @{ Extension = ".yaml"; ExpectedLanguage = "yaml" },
+    @{ Extension = ".go"; ExpectedLanguage = "go" },
+    @{ Extension = ".rs"; ExpectedLanguage = "rust" }
+)
+
+foreach ($mapping in $extensionMappings) {
+    Assert-Test "Extension '$($mapping.Extension)' maps to '$($mapping.ExpectedLanguage)'" {
+        $lang = $languagesJson.list | Where-Object { $_.id -eq $mapping.ExpectedLanguage }
+        if ($null -eq $lang) { throw "Language '$($mapping.ExpectedLanguage)' not found" }
+        $mapping.Extension -in $lang.extensions
+    }
+}
+
+# ─── Test Group 7: Version Consistency ────────────────────────────────
+Write-Host "`n--- Version Consistency ---" -ForegroundColor Yellow
+
+Assert-Test "All NLS files in editor directory have matching versions" {
+    $editorDir = Join-Path $minDir "vs" "editor"
+    $nlsFiles = Get-ChildItem -Path $editorDir -Filter "editor.main.nls*.js" -ErrorAction SilentlyContinue
+    if ($nlsFiles.Count -eq 0) { throw "No NLS files found" }
+
+    $loaderContent = Get-Content $loaderJsPath -Raw
+    $null = $loaderContent -match 'Version:\s*(\d+\.\d+\.\d+)'
+    $loaderVersion = $Matches[1]
+
+    foreach ($nlsFile in $nlsFiles) {
+        $content = Get-Content $nlsFile.FullName -Raw -ErrorAction SilentlyContinue
+        if ($content -and $content -match 'Version:\s*(\d+\.\d+\.\d+)') {
+            if ($Matches[1] -ne $loaderVersion) {
+                throw "Version mismatch in $($nlsFile.Name): expected $loaderVersion, found $($Matches[1])"
+            }
+        }
+    }
+    $true
+}
+
+Assert-Test "basic-languages files have matching versions" {
+    $loaderContent = Get-Content $loaderJsPath -Raw
+    $null = $loaderContent -match 'Version:\s*(\d+\.\d+\.\d+)'
+    $loaderVersion = $Matches[1]
+
+    $basicLangsDir = Join-Path $minDir "vs" "basic-languages"
+    # Spot-check a few language files
+    $checkFiles = @("javascript/javascript.js", "python/python.js", "html/html.js")
+    foreach ($file in $checkFiles) {
+        $filePath = Join-Path $basicLangsDir $file
+        if (Test-Path $filePath) {
+            $content = Get-Content $filePath -Raw
+            if ($content -match 'Version:\s*(\d+\.\d+\.\d+)') {
+                if ($Matches[1] -ne $loaderVersion) {
+                    throw "Version mismatch in $file: expected $loaderVersion, found $($Matches[1])"
+                }
+            }
+        }
+    }
+    $true
+}
+
+# ─── Summary ──────────────────────────────────────────────────────────
+Write-Host ""
+Write-Host "=== Test Summary ===" -ForegroundColor Cyan
+Write-Host "Passed: $testsPassed" -ForegroundColor Green
+Write-Host "Failed: $testsFailed" -ForegroundColor $(if ($testsFailed -gt 0) { "Red" } else { "Green" })
+Write-Host "Total:  $($testsPassed + $testsFailed)"
+
+if ($testsFailed -gt 0) {
+    Write-Host "`nFailed tests:" -ForegroundColor Red
+    $testResults | Where-Object { $_.Status -eq "FAIL" } | ForEach-Object {
+        Write-Host "  - $($_.Name): $($_.Error)" -ForegroundColor Red
+    }
+    exit 1
+}
+
+Write-Host "`nAll tests passed!" -ForegroundColor Green
+exit 0

.github/scripts/update-monaco-editor.ps1

@@ -0,0 +1,162 @@
+<#
+.SYNOPSIS
+    Updates the Monaco Editor in PowerToys to the latest (or specified) version.
+
+.DESCRIPTION
+    This script automates the Monaco Editor update process described in
+    doc/devdocs/common/FilePreviewCommon.md:
+      1. Downloads Monaco editor via npm
+      2. Copies the min folder into src/Monaco/monacoSRC/
+      3. Generates the monaco_languages.json file using Puppeteer (headless browser)
+
+.PARAMETER Version
+    The Monaco Editor npm version to install. Defaults to "latest".
+
+.PARAMETER RepoRoot
+    The root of the PowerToys repository. Defaults to the repo root relative to this script.
+
+.EXAMPLE
+    ./update-monaco-editor.ps1
+    ./update-monaco-editor.ps1 -Version "0.55.1"
+#>
+[CmdletBinding()]
+param(
+    [Parameter()]
+    [string]$Version = "latest",
+
+    [Parameter()]
+    [string]$RepoRoot
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+if (-not $RepoRoot) {
+    $RepoRoot = (Resolve-Path (Join-Path $PSScriptRoot ".." "..")).Path
+}
+
+$monacoDir = Join-Path $RepoRoot "src" "Monaco"
+$monacoSrcDir = Join-Path $monacoDir "monacoSRC"
+$languagesJsonPath = Join-Path $monacoDir "monaco_languages.json"
+$tempDir = Join-Path ([System.IO.Path]::GetTempPath()) "monaco-update-$([System.Guid]::NewGuid().ToString('N').Substring(0, 8))"
+
+Write-Host "=== Monaco Editor Update Script ==="
+Write-Host "Repository root: $RepoRoot"
+Write-Host "Target version: $Version"
+Write-Host "Temp directory: $tempDir"
+
+# Verify prerequisites
+$npmPath = Get-Command npm -ErrorAction SilentlyContinue
+if (-not $npmPath) {
+    throw "npm is required but not found in PATH. Please install Node.js."
+}
+
+$nodePath = Get-Command node -ErrorAction SilentlyContinue
+if (-not $nodePath) {
+    throw "node is required but not found in PATH. Please install Node.js."
+}
+
+# Verify repo structure
+if (-not (Test-Path $monacoDir)) {
+    throw "Monaco directory not found at: $monacoDir"
+}
+
+try {
+    # Step 1: Download Monaco via npm
+    Write-Host "`n--- Step 1: Downloading Monaco Editor ($Version) via npm ---"
+    New-Item -ItemType Directory -Path $tempDir -Force | Out-Null
+
+    Push-Location $tempDir
+    try {
+        $versionSpec = if ($Version -eq "latest") { "monaco-editor@latest" } else { "monaco-editor@$Version" }
+        npm init -y 2>&1 | Out-Null
+        npm install $versionSpec 2>&1
+
+        if ($LASTEXITCODE -ne 0) {
+            throw "npm install failed with exit code $LASTEXITCODE"
+        }
+    }
+    finally {
+        Pop-Location
+    }
+
+    $downloadedMinDir = Join-Path $tempDir "node_modules" "monaco-editor" "min"
+    if (-not (Test-Path $downloadedMinDir)) {
+        throw "Downloaded Monaco min directory not found at: $downloadedMinDir"
+    }
+
+    # Detect the downloaded version from loader.js
+    $loaderJsPath = Join-Path $downloadedMinDir "vs" "loader.js"
+    if (-not (Test-Path $loaderJsPath)) {
+        throw "loader.js not found in downloaded Monaco package"
+    }
+
+    $loaderContent = Get-Content $loaderJsPath -Raw
+    if ($loaderContent -match 'Version:\s*(\d+\.\d+\.\d+)') {
+        $newVersion = $Matches[1]
+        Write-Host "Downloaded Monaco version: $newVersion"
+    }
+    else {
+        Write-Warning "Could not detect version from loader.js"
+        $newVersion = $Version
+    }
+
+    # Step 2: Replace monacoSRC/min folder
+    Write-Host "`n--- Step 2: Replacing monacoSRC/min with new version ---"
+    $targetMinDir = Join-Path $monacoSrcDir "min"
+
+    if (Test-Path $targetMinDir) {
+        Write-Host "Removing existing min directory..."
+        Remove-Item -Recurse -Force $targetMinDir
+    }
+
+    Write-Host "Copying new min directory..."
+    Copy-Item -Recurse -Force $downloadedMinDir $targetMinDir
+
+    # Step 3: Generate monaco_languages.json using Puppeteer
+    Write-Host "`n--- Step 3: Generating monaco_languages.json (Puppeteer) ---"
+
+    # Install Puppeteer in the temp directory
+    Push-Location $tempDir
+    try {
+        Write-Host "Installing Puppeteer..."
+        npm install puppeteer 2>&1
+
+        if ($LASTEXITCODE -ne 0) {
+            throw "npm install puppeteer failed with exit code $LASTEXITCODE"
+        }
+    }
+    finally {
+        Pop-Location
+    }
+
+    $generateScript = Join-Path $PSScriptRoot "generate-monaco-languages.js"
+
+    # Set NODE_PATH so the generate script can find puppeteer from the temp dir
+    $env:NODE_PATH = Join-Path $tempDir "node_modules"
+    node $generateScript $monacoDir
+
+    if ($LASTEXITCODE -ne 0) {
+        throw "Failed to generate monaco_languages.json (exit code: $LASTEXITCODE)"
+    }
+
+    if (-not (Test-Path $languagesJsonPath)) {
+        throw "monaco_languages.json was not generated at: $languagesJsonPath"
+    }
+
+    Write-Host "`n=== Monaco Editor update complete ==="
+    Write-Host "Updated to version: $newVersion"
+    Write-Host "Languages JSON: $languagesJsonPath"
+
+    # Output the new version for the workflow to use
+    Write-Output "MONACO_VERSION=$newVersion"
+}
+finally {
+    # Clean up temp directory
+    if (Test-Path $tempDir) {
+        Remove-Item -Recurse -Force $tempDir -ErrorAction SilentlyContinue
+    }
+
+    # Remove NODE_PATH override
+    Remove-Item Env:\NODE_PATH -ErrorAction SilentlyContinue
+}

.github/workflows/update-monaco-editor.yml

@@ -0,0 +1,135 @@
+# Update Monaco Editor
+#
+# Automates the Monaco Editor update process described in
+# doc/devdocs/common/FilePreviewCommon.md:
+#   1. Downloads the latest (or specified) Monaco Editor from npm
+#   2. Replaces src/Monaco/monacoSRC/min with the new version
+#   3. Regenerates monaco_languages.json via Puppeteer (headless browser)
+#   4. Runs validation tests
+#   5. Creates a pull request with the changes
+#
+# Trigger manually via workflow_dispatch.
+# Uncomment the schedule block below to enable weekly automatic checks.
+
+name: Update Monaco Editor
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Monaco Editor version (e.g. "0.55.1"). Leave empty for latest.'
+        required: false
+        default: ''
+        type: string
+
+  # Uncomment the following to enable weekly automatic update checks:
+  # schedule:
+  #   - cron: '0 9 * * 1'  # Every Monday at 9:00 UTC
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  update-monaco:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Get current Monaco version
+        id: current_version
+        shell: bash
+        run: |
+          CURRENT=$(grep -oP 'Version:\s*\K[\d.]+' src/Monaco/monacoSRC/min/vs/loader.js || echo "unknown")
+          echo "version=$CURRENT" >> "$GITHUB_OUTPUT"
+          echo "Current Monaco version: $CURRENT"
+
+      - name: Run Monaco update script
+        id: update
+        shell: pwsh
+        run: |
+          $version = '${{ inputs.version }}'
+          if ([string]::IsNullOrWhiteSpace($version)) {
+            $version = 'latest'
+          }
+          $output = & ./.github/scripts/update-monaco-editor.ps1 -Version $version -RepoRoot $env:GITHUB_WORKSPACE
+          # Extract version from script output
+          $versionLine = $output | Select-String -Pattern '^MONACO_VERSION=' | Select-Object -First 1
+          if ($versionLine) {
+            $newVersion = $versionLine.ToString().Split('=')[1]
+            echo "new_version=$newVersion" >> $env:GITHUB_OUTPUT
+            Write-Host "New Monaco version: $newVersion"
+          }
+
+      - name: Run validation tests
+        shell: pwsh
+        run: |
+          ./.github/scripts/tests/validate-monaco-update.tests.ps1 -RepoRoot $env:GITHUB_WORKSPACE
+
+      - name: Check for changes
+        id: changes
+        shell: bash
+        run: |
+          if git diff --quiet; then
+            echo "has_changes=false" >> "$GITHUB_OUTPUT"
+            echo "No changes detected - Monaco may already be up to date."
+          else
+            echo "has_changes=true" >> "$GITHUB_OUTPUT"
+            CHANGED_FILES=$(git diff --stat | tail -1)
+            echo "changed_files=$CHANGED_FILES" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Create pull request
+        if: steps.changes.outputs.has_changes == 'true'
+        uses: peter-evans/create-pull-request@v7
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          commit-message: "Update Monaco Editor to ${{ steps.update.outputs.new_version }}"
+          title: "Update Monaco Editor from ${{ steps.current_version.outputs.version }} to ${{ steps.update.outputs.new_version }}"
+          body: |
+            ## Summary
+
+            Automated update of the Monaco Editor dependency.
+
+            **Previous version:** ${{ steps.current_version.outputs.version }}
+            **New version:** ${{ steps.update.outputs.new_version }}
+
+            ## Changes
+
+            - Updated `src/Monaco/monacoSRC/min/` with the new Monaco Editor release
+            - Regenerated `src/Monaco/monaco_languages.json`
+
+            ## Validation
+
+            The following automated checks passed:
+            - ✅ `loader.js` contains valid version header
+            - ✅ Directory structure intact (`vs/editor/`, `vs/basic-languages/`, `vs/base/`, `vs/language/`)
+            - ✅ `monaco_languages.json` is valid JSON with expected structure
+            - ✅ All expected built-in languages are present (32+ core languages verified)
+            - ✅ All PowerToys custom languages registered (`reg`, `gitignore`, `srt`)
+            - ✅ All custom extension mappings present (`cppExt`, `xmlExt`, `txtExt`, etc.)
+            - ✅ No duplicate language IDs
+            - ✅ Version consistency across Monaco files
+            - ✅ Extension-to-language mappings verified (`.js`→javascript, `.py`→python, etc.)
+
+            ## Manual Verification
+
+            Before merging, please verify:
+            - [ ] File Explorer Dev File Preview works correctly
+            - [ ] Peek module previews code files properly
+            - [ ] Registry Preview module functions normally
+
+            ## Reference
+
+            - [Monaco Editor update docs](doc/devdocs/common/FilePreviewCommon.md#update-monaco-editor)
+            - [Monaco Editor releases](https://github.com/microsoft/monaco-editor/releases)
+          branch: automated/update-monaco-editor
+          delete-branch: true
+          labels: |
+            dependencies