Refactor document name sanitization for consistent filename generation

- Introduced FdsDocumentNames class to centralize the logic for sanitizing document names used in downloads.
- Updated FdsMfr to utilize the new SafeFileName method for generating safe filenames.
- Enhanced documentation for FdsDocumentNames and its methods to clarify usage and purpose.
- Added global.json file to configure testing framework settings.

Fuchs/Controllers/IntranetController.Invoices2.cs

@@ -329,18 +329,12 @@ public partial class IntranetController
     }
 
     /// <summary>
-    /// Download filename for a regenerated document. DocumentName is derived from the user-typed
-    /// invoice title, so it can carry path separators ("Wartung 2025/26") and stray editor markup;
-    /// mirrors the cleanup <c>FdsMfr.GetReportDoc</c> applies to stored documents.
+    /// Download filename for a regenerated document — the one shared sanitiser
+    /// (<see cref="fds.FdsDocumentNames.SafeFileName"/>) that <c>FdsMfr.GetReportDoc</c> also
+    /// applies to stored documents, so both paths name the same DocumentName identically.
     /// </summary>
-    internal static string SafeDocumentFileName(string documentName, string fallback)
-    {
-        string name = (documentName ?? "").Replace("<p>", "").Replace("</p>", "").Trim();
-        if (name.Length == 0) name = fallback;
-        foreach (char c in Path.GetInvalidFileNameChars())
-            name = name.Replace(c, '_');
-        return name.Length == 0 ? fallback : name;
-    }
+    internal static string SafeDocumentFileName(string documentName, string fallback) =>
+        fds.FdsDocumentNames.SafeFileName(documentName, fallback);
 
     private async Task<IActionResult> HandleReportDocByName(string fn, string id, string code)
     {

Fuchs/Controllers/IntranetController.PdfPreview.cs

@@ -36,6 +36,28 @@ public partial class IntranetController
         {
             var result = await render();
             sw.Stop();
+
+            // The client (postXT) gives up after a fixed timeout and aborts the connection while a
+            // slow render/regenerate-on-miss (ADR 0025) is still running server-side; that work is
+            // deliberately NOT cancelled — the regenerated document must still be stored so the
+            // next click is fast (ADR 0025) — but writing the now-finished result back to a socket
+            // the client already closed would only surface as a low-level framework/Kestrel
+            // exception that never reaches an EventId'd `_logger` call: it is either below the SQL
+            // sink's Warning floor or purely a debugger first-chance notification that never goes
+            // through ILogger at all — exactly the "exception in the debug console but nothing in
+            // fds__debuglog" gap. Recognise the disconnect here instead and log it deliberately, at
+            // Warning, so it is guaranteed to land in fds__debuglog (ADR 0024) — and skip the write.
+            if (HttpContext.RequestAborted.IsCancellationRequested)
+            {
+                FuchsTelemetry.PdfPreviews.Add(1,
+                    new KeyValuePair<string, object?>("what", what),
+                    new KeyValuePair<string, object?>("outcome", "client-disconnected"));
+                _logger.LogWarning(
+                    "PDF preview {What} ref={RefId} user={User} finished in {Ms} ms but the client had already disconnected (timeout) — result discarded",
+                    what, refId, UserAccountID, sw.ElapsedMilliseconds);
+                return new EmptyResult();
+            }
+
             // A draft session that expired between page load and preview click is an expected
             // client-driven outcome (the browser reopens the draft), not a render failure — keep
             // it out of the failure telemetry/logging this guard exists to produce.
@@ -51,6 +73,20 @@ public partial class IntranetController
         {
             sw.Stop();
             act?.SetStatus(ActivityStatusCode.Error, ex.Message);
+            // Same client-gone rationale as above, but the render itself threw (e.g. it tried to
+            // write partial output to the aborted connection). Still an expected outcome of a
+            // client timeout, not a render defect — logged at Warning, not Error, but still
+            // guaranteed to reach fds__debuglog (ADR 0024) rather than only a debug console.
+            if (HttpContext.RequestAborted.IsCancellationRequested)
+            {
+                FuchsTelemetry.PdfPreviews.Add(1,
+                    new KeyValuePair<string, object?>("what", what),
+                    new KeyValuePair<string, object?>("outcome", "client-disconnected"));
+                _logger.LogWarning(ex,
+                    "PDF preview {What} ref={RefId} user={User} failed after {Ms} ms because the client had already disconnected",
+                    what, refId, UserAccountID, sw.ElapsedMilliseconds);
+                return new EmptyResult();
+            }
             FuchsTelemetry.PdfPreviews.Add(1,
                 new KeyValuePair<string, object?>("what", what),
                 new KeyValuePair<string, object?>("outcome", "failure"));