Skyline: Convert WebClient use to HttpClient

.cursorrules

@@ -55,6 +55,10 @@ docs = [
 - Use fenced code blocks only for relevant snippets or commands.
 - Default to read-only discovery before edits; then apply focused edits.
 
+[async_patterns]
+# See STYLEGUIDE.md for comprehensive async/await guidelines
+reference = "STYLEGUIDE.md"
+
 [build_and_testing]
 - LLM agents CANNOT build or run this project directly.
 - Build and test operations must be performed by the developer using Visual Studio.
@@ -63,34 +67,8 @@ docs = [
 - Do not attempt to run tests or execute the application.
 
 [file_headers]
-standard_header = """
-/*
- * Original author: [Author Name] <[email] .at. [domain]>,
- *                  [Affiliation]
- * AI assistance: Cursor (Claude Sonnet 4) <cursor .at. anysphere.co>
- *
- * Copyright [Year] University of Washington - Seattle, WA
- * 
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-"""
-ai_attribution = {
-  required = "Always include AI assistance line when code is created or significantly modified with AI tools"
-  format = "Cursor ([model names]) <cursor .at. anysphere.co>"
-  position = "After original author, before copyright"
-  email_format = "Use .at. format to avoid spam harvesting"
-  multiple_models = "List all models used if multiple AI systems contributed significantly"
-}
+# See STYLEGUIDE.md for file header format and AI attribution guidelines
+reference = "STYLEGUIDE.md"
 
 [testing]
 # See STYLEGUIDE.md for comprehensive testing guidelines

STYLEGUIDE.md

@@ -60,8 +60,9 @@ Additional guidance:
 - Enum members: `snake_case` (e.g., `not_set`).
 
 ## Whitespace and formatting
-- Tabs are disallowed; use spaces. Do not change existing files’ indentation, but when adding new code use spaces.
+- Tabs are disallowed; use spaces. Do not change existing files' indentation, but when adding new code use spaces.
 - Avoid mixing tabs and spaces. Align with existing file formatting.
+- **Line endings**: Use Windows-style line endings (`\r\n`, CRLF) for all files. This is the standard for Windows development and matches the team's development environment. When creating or modifying files, ensure line endings are `\r\n`, not Unix-style `\n` (LF).
 
 ## Tools
 - We develop with Visual Studio 2022 and ReSharper; aim for warning-free under its inspections.
@@ -142,6 +143,46 @@ All source files should include the standard header with copyright and license i
 - Existing files: Keep existing `u.washington.edu` format (no need to change)
 - Both formats are acceptable
 
+## Asynchronous programming patterns
+
+### CRITICAL: No async/await keywords
+- **DO NOT use `async`/`await` keywords** in C# code
+- Use `AsyncUtil.RunAsync()` and `CommonAsyncUtil.RunAsync()` for background operations
+- Use `Control.Invoke()` and `Control.BeginInvoke()` to return to UI thread
+- See `DocumentationViewer.cs` for example implementation pattern
+
+### Background operation pattern
+```csharp
+// Background operation with UI callback
+CommonActionUtil.RunAsync(() =>
+{
+    try
+    {
+        // Background work here
+        var result = DoBackgroundWork();
+
+        // Return to UI thread for updates
+        RunUI(() => UpdateUI(result));
+    }
+    catch (Exception ex)
+    {
+        RunUI(() => CommonAlertDlg.ShowException(this, ex));
+    }
+});
+
+private void RunUI(Action act)
+{
+    Invoke(act);
+}
+```
+
+### WebClient replacement pattern
+When replacing WebClient with HttpClient:
+- Maintain synchronous interface for existing callers
+- Use `RunAsync()` to execute HTTP operations in background
+- Use `Control.Invoke()` to return results to UI thread
+- Preserve existing error handling patterns
+
 ## Testing guidelines
 
 ### Test project structure

pwiz_tools/Shared/CommonUtil/CommonUtil.csproj

@@ -101,6 +101,7 @@
       <RequiredTargetFramework>3.5</RequiredTargetFramework>
     </Reference>
     <Reference Include="System.Drawing" />
+    <Reference Include="System.Net.Http" />
     <Reference Include="System.Security" />
     <Reference Include="System.Web" />
     <Reference Include="System.Windows.Forms" />
@@ -224,6 +225,7 @@
     <Compile Include="Collections\IndexedSubList.cs" />
     <Compile Include="SystemUtil\ConcurrencyVisualizer.cs" />
     <Compile Include="SystemUtil\FormUtil.cs" />
+    <Compile Include="SystemUtil\HttpClientWithProgress.cs" />
     <Compile Include="SystemUtil\Immutable.cs" />
     <Compile Include="SystemUtil\IProgressMonitor.cs" />
     <Compile Include="SystemUtil\LocalizationHelper.cs" />

pwiz_tools/Shared/CommonUtil/Properties/Resources.resx

@@ -160,4 +160,25 @@
   <data name="FileEx_SafeDelete_Directory_could_not_be_found___0_" xml:space="preserve">
     <value>Directory could not be found: {0}</value>
   </data>
+  <data name="HttpClientWithProgress_MapHttpException_The_request_to__0__timed_out__Please_try_again_" xml:space="preserve">
+    <value>The request to {0} timed out. Please try again.</value>
+  </data>
+  <data name="HttpClientWithProgress_MapHttpException_No_network_connection_detected__Please_check_your_internet_connection_and_try_again_" xml:space="preserve">
+    <value>No network connection detected. Please check your internet connection and try again.</value>
+  </data>
+  <data name="HttpClientWithProgress_MapHttpException_Failed_to_resolve_host__0___Please_check_your_DNS_settings_or_VPN_proxy_" xml:space="preserve">
+    <value>Failed to resolve host {0}. Please check your DNS settings or VPN/proxy.</value>
+  </data>
+  <data name="HttpClientWithProgress_MapHttpException_Failed_to_connect_to__0___Please_check_your_network_connection__VPN_proxy__or_firewall_" xml:space="preserve">
+    <value>Failed to connect to {0}. Please check your network connection, VPN/proxy, or firewall.</value>
+  </data>
+  <data name="HttpClientWithProgress_MapHttpException_The_connection_was_lost_during_download__Please_check_your_internet_connection_and_try_again_" xml:space="preserve">
+    <value>The connection was lost during download. Please check your internet connection and try again.</value>
+  </data>
+  <data name="HttpClientWithProgress_ReadWithTimeout_The_read_operation_timed_out_while_downloading_from__0__" xml:space="preserve">
+    <value>The read operation timed out while downloading from {0}.</value>
+  </data>
+  <data name="HttpClientWithProgress_MapHttpException_server" xml:space="preserve">
+    <value>server</value>
+  </data>
 </root>