fix(hooks): preserve WSL desktop notify success path

Merge findPowerShell version check and isBurntToastAvailable check
into a single notifyWindows call. Now just tries to send directly;
if it fails, tries next PowerShell path. Version field was unused.

Net effect: up to 3 spawns reduced to 1 in the happy path.

hooks/hooks.json

@@ -310,7 +310,7 @@
             "timeout": 10
           }
         ],
-        "description": "Send macOS desktop notification with task summary when Claude responds"
+        "description": "Send desktop notification (macOS/WSL) with task summary when Claude responds"
       }
     ],
     "SessionEnd": [

scripts/hooks/desktop-notify.js

@@ -3,9 +3,11 @@
  * Desktop Notification Hook (Stop)
  *
  * Sends a native desktop notification with the task summary when Claude
- * finishes responding.  Currently supports macOS (osascript); other
- * platforms exit silently.  Windows (PowerShell) and Linux (notify-send)
- * support is planned.
+ * finishes responding.  Supports:
+ *   - macOS: osascript (native)
+ *   - WSL: PowerShell 7 or Windows PowerShell + BurntToast module
+ *
+ * On WSL, if BurntToast is not installed, logs a tip for installation.
  *
  * Hook ID : stop:desktop-notify
  * Profiles: standard, strict
@@ -19,6 +21,64 @@ const { isMacOS, log } = require('../lib/utils');
 const TITLE = 'Claude Code';
 const MAX_BODY_LENGTH = 100;
 
+/**
+ * Memoized WSL detection at module load (avoids repeated /proc/version reads).
+ */
+let isWSL = false;
+if (process.platform === 'linux') {
+  try {
+    isWSL = require('fs').readFileSync('/proc/version', 'utf8').toLowerCase().includes('microsoft');
+  } catch {
+    isWSL = false;
+  }
+}
+
+/**
+ * Find available PowerShell executable on WSL.
+ * Returns first accessible path, or null if none found.
+ */
+function findPowerShell() {
+  if (!isWSL) return null;
+
+  const candidates = [
+    'pwsh.exe',        // WSL interop resolves from Windows PATH
+    'powershell.exe',  // WSL interop for Windows PowerShell
+    '/mnt/c/Program Files/PowerShell/7/pwsh.exe',      // PowerShell 7 (default install)
+    '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe', // Windows PowerShell
+  ];
+
+  for (const path of candidates) {
+    try {
+      const result = spawnSync(path, ['-Command', 'exit 0'],
+        { stdio: ['ignore', 'pipe', 'ignore'], timeout: 1000 });
+      if (result.status === 0) {
+        return path;
+      }
+    } catch {
+      // continue
+    }
+  }
+  return null;
+}
+
+/**
+ * Send a Windows Toast notification via PowerShell BurntToast.
+ * Returns true on success, false on failure.
+ */
+function notifyWindows(pwshPath, title, body) {
+  const safeBody = body.replace(/'/g, "''");
+  const safeTitle = title.replace(/'/g, "''");
+  const command = `Import-Module BurntToast; New-BurntToastNotification -Text '${safeTitle}', '${safeBody}'`;
+  const result = spawnSync(pwshPath, ['-Command', command],
+    { stdio: ['ignore', 'pipe', 'pipe'], timeout: 5000 });
+  if (result.error || result.status !== 0) {
+    const stderr = typeof result.stderr?.toString === 'function' ? result.stderr.toString().trim() : '';
+    log(`[DesktopNotify] BurntToast failed (exit ${result.status}): ${result.error ? result.error.message : stderr}`);
+    return false;
+  }
+  return true;
+}
+
 /**
  * Extract a short summary from the last assistant message.
  * Takes the first non-empty line and truncates to MAX_BODY_LENGTH chars.
@@ -53,20 +113,28 @@ function notifyMacOS(title, body) {
   }
 }
 
-// TODO: future platform support
-// function notifyWindows(title, body) { ... }
-// function notifyLinux(title, body) { ... }
-
 /**
  * Fast-path entry point for run-with-flags.js (avoids extra process spawn).
  */
 function run(raw) {
   try {
-    if (!isMacOS) return raw;
-
     const input = raw.trim() ? JSON.parse(raw) : {};
     const summary = extractSummary(input.last_assistant_message);
-    notifyMacOS(TITLE, summary);
+
+    if (isMacOS) {
+      notifyMacOS(TITLE, summary);
+    } else if (isWSL) {
+      const ps = findPowerShell();
+      if (ps && notifyWindows(ps, TITLE, summary)) {
+        // notification sent successfully
+      } else if (ps) {
+        // PowerShell found but BurntToast not available
+        log('[DesktopNotify] Tip: Install BurntToast module to enable notifications');
+      } else {
+        // No PowerShell found
+        log('[DesktopNotify] Tip: Install BurntToast module in PowerShell for notifications');
+      }
+    }
   } catch (err) {
     log(`[DesktopNotify] Error: ${err.message}`);
   }

tests/hooks/desktop-notify.test.js

@@ -0,0 +1,118 @@
+/**
+ * Tests for scripts/hooks/desktop-notify.js
+ */
+
+const assert = require('assert');
+const fs = require('fs');
+const Module = require('module');
+const path = require('path');
+
+const modulePath = path.join(__dirname, '..', '..', 'scripts', 'hooks', 'desktop-notify.js');
+const moduleSource = fs.readFileSync(modulePath, 'utf8');
+
+function test(name, fn) {
+  try {
+    fn();
+    console.log(`  ✓ ${name}`);
+    return true;
+  } catch (error) {
+    console.log(`  ✗ ${name}`);
+    console.log(`    Error: ${error.message}`);
+    return false;
+  }
+}
+
+function loadDesktopNotify({ procVersion = 'Linux version microsoft', spawnImpl, isMacOS = false }) {
+  const logs = [];
+  const mod = new Module(modulePath, module);
+  mod.filename = modulePath;
+  mod.paths = Module._nodeModulePaths(path.dirname(modulePath));
+
+  const originalRequire = mod.require.bind(mod);
+  mod.require = request => {
+    if (request === 'child_process') {
+      return { spawnSync: spawnImpl };
+    }
+    if (request === '../lib/utils') {
+      return {
+        isMacOS,
+        log: message => logs.push(message),
+      };
+    }
+    if (request === 'fs') {
+      return {
+        ...fs,
+        readFileSync(target, encoding) {
+          if (target === '/proc/version') {
+            return procVersion;
+          }
+          return fs.readFileSync(target, encoding);
+        }
+      };
+    }
+    return originalRequire(request);
+  };
+
+  const platformDescriptor = Object.getOwnPropertyDescriptor(process, 'platform');
+  Object.defineProperty(process, 'platform', {
+    configurable: true,
+    value: 'linux',
+  });
+
+  try {
+    mod._compile(moduleSource, modulePath);
+  } finally {
+    Object.defineProperty(process, 'platform', platformDescriptor);
+  }
+
+  return { run: mod.exports.run, logs };
+}
+
+let passed = 0;
+let failed = 0;
+
+if (
+  test('successful WSL toast does not log BurntToast install guidance', () => {
+    const calls = [];
+    const { run, logs } = loadDesktopNotify({
+      spawnImpl(command, args) {
+        calls.push({ command, args });
+        if (calls.length === 1) {
+          return { status: 0, stderr: Buffer.from('') };
+        }
+        return { status: 0, stderr: Buffer.from('') };
+      }
+    });
+
+    const payload = JSON.stringify({ last_assistant_message: 'Build completed successfully' });
+    assert.strictEqual(run(payload), payload);
+    assert.strictEqual(calls.length, 2, 'Expected PowerShell probe and notification send');
+    assert.strictEqual(logs.length, 0, `Expected no warnings, got: ${logs.join('\n')}`);
+  })
+)
+  passed++;
+else failed++;
+
+if (
+  test('failed WSL toast logs failure and install guidance once', () => {
+    const { run, logs } = loadDesktopNotify({
+      spawnImpl(command, args) {
+        if (args[1] === 'exit 0') {
+          return { status: 0, stderr: Buffer.from('') };
+        }
+        return { status: 1, stderr: Buffer.from('module missing') };
+      }
+    });
+
+    const payload = JSON.stringify({ last_assistant_message: 'Done' });
+    assert.strictEqual(run(payload), payload);
+    assert.ok(logs.some(message => message.includes('BurntToast failed')), 'Expected BurntToast failure log');
+    assert.ok(logs.some(message => message.includes('Install BurntToast module')), 'Expected install tip');
+  })
+)
+  passed++;
+else failed++;
+
+console.log(`\nPassed: ${passed}`);
+console.log(`Failed: ${failed}`);
+process.exit(failed > 0 ? 1 : 0);