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.

.github/copilot-instructions.md

@@ -14,7 +14,7 @@
 - Routes: `/{fn?}/{id?}/{code?}` → `IntranetController.Index`; `/do/{fn?}/{id?}/{code?}` → `IntranetController.Do`.
 - Build app: `dotnet build Fuchs/Fuchs.csproj -c Debug`. Build all: `dotnet build Fuchs_Intranet.slnx -c Debug`.
 - Frontend assets are source-built: run the gulp tasks in `Fuchs/` (`npx gulp min`, or `npx gulp all` when copied/static assets also need refreshing) whenever JS or SCSS/CSS sources change. The generated files under `Fuchs/wwwroot/web/` are what the app serves.
-- Test: `dotnet test Fuchs.Tests/Fuchs.Tests.csproj -c Debug`.
+- Test: `dotnet test --project Fuchs.Tests/Fuchs.Tests.csproj -c Debug` (the root `global.json` opts `dotnet test` into the Microsoft.Testing.Platform runner that xunit.v3 needs on the .NET 10 SDK; the positional-path form no longer works).
 - Always build **and** run the test suite before committing. CA1416 (platform-compatibility) is suppressed solution-wide via the root `.editorconfig` — the app is Windows-only. The build may still emit other pre-existing analyzer warnings; only treat `: error` lines as failures.
 - Submodules include the OCORE projects and `eRechnungLib` (ZUGFeRD/Factur-X + XRechnung generation) — invoices are moving to eRechnung output.
 - Project structure (relative to `Fuchs/`):

CLAUDE.md

@@ -16,7 +16,7 @@
 ## Build & Test (workflow)
 - Build app: `dotnet build Fuchs/Fuchs.csproj -c Debug`. Build all: `dotnet build Fuchs_Intranet.slnx -c Debug`.
 - Frontend assets are source-built: run the gulp tasks in `Fuchs/` (`npx gulp min`, or `npx gulp all` when copied/static assets also need refreshing) whenever JS or SCSS/CSS sources change. The generated files under `Fuchs/wwwroot/web/` are what the app serves.
-- Test: `dotnet test Fuchs.Tests/Fuchs.Tests.csproj -c Debug`.
+- Test: `dotnet test --project Fuchs.Tests/Fuchs.Tests.csproj -c Debug` (the root `global.json` opts `dotnet test` into the Microsoft.Testing.Platform runner that xunit.v3 needs on the .NET 10 SDK; the positional-path form no longer works).
 - Always build **and** run the test suite before committing. CA1416 (platform-compatibility) is suppressed solution-wide via the root `.editorconfig` — the app is Windows-only. The build may still emit other pre-existing analyzer warnings; only treat `: error` lines as failures.
 - Commit only when asked. Co-author trailer: `Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>`.
 - The working tree may contain an untracked `Fuchs_Database/` SQL project — it is **not** part of app changes; never `git add -A` it into an unrelated commit. Stage explicit paths.

CODEX.md

@@ -16,7 +16,7 @@
 ## Build & Test (workflow)
 - Build app: `dotnet build Fuchs/Fuchs.csproj -c Debug`. Build all: `dotnet build Fuchs_Intranet.slnx -c Debug`.
 - Frontend assets are source-built: run the gulp tasks in `Fuchs/` (`npx gulp min`, or `npx gulp all` when copied/static assets also need refreshing) whenever JS or SCSS/CSS sources change. The generated files under `Fuchs/wwwroot/web/` are what the app serves.
-- Test: `dotnet test Fuchs.Tests/Fuchs.Tests.csproj -c Debug`.
+- Test: `dotnet test --project Fuchs.Tests/Fuchs.Tests.csproj -c Debug` (the root `global.json` opts `dotnet test` into the Microsoft.Testing.Platform runner that xunit.v3 needs on the .NET 10 SDK; the positional-path form no longer works).
 - Always build **and** run the test suite before committing. CA1416 (platform-compatibility) is suppressed solution-wide via the root `.editorconfig` — the app is Windows-only. The build may still emit other pre-existing analyzer warnings; only treat `: error` lines as failures.
 - Commit only when asked. Co-author trailer, when requested: `Co-Authored-By: Codex <noreply@openai.com>`.
 - The working tree may contain an untracked `Fuchs_Database/` SQL project — it is **not** part of app changes; never `git add -A` it into an unrelated commit. Stage explicit paths.

Fuchs.Tests/ReportDocFileNameTests.cs

@@ -26,8 +26,59 @@ public class ReportDocFileNameTests
     [InlineData("")]
     [InlineData("   ")]
     [InlineData("<p></p>")]
+    [InlineData("<p> </p>")]
     public void SafeDocumentFileName_EmptyDocumentName_UsesFallback(string? documentName)
     {
         Assert.Equal("Rechnung_W7VAL.pdf", IntranetController.SafeDocumentFileName(documentName!, "Rechnung_W7VAL.pdf"));
     }
+
+    /// <summary>
+    /// The stored-document path (<c>FdsMfr.GetReportDoc</c>) replaced exactly these characters
+    /// before the sanitiser was shared: <c>= &gt; | ! &lt; /</c>. The shared helper must still
+    /// produce the identical result for them — unifying the two paths may not loosen either.
+    /// </summary>
+    [Theory]
+    [InlineData("a>b|c!d<e/f=g.pdf", "a_b_c_d_e_f_g.pdf")]
+    [InlineData("<p>Summe=100!.pdf</p>", "Summe_100_.pdf")]
+    public void SafeFileName_KeepsEveryReplacementTheStoredDocumentPathMade(string documentName, string expected)
+    {
+        Assert.Equal(expected, fds.FdsDocumentNames.SafeFileName(documentName, "X.pdf"));
+    }
+
+    /// <summary>
+    /// Characters the old stored-document path did NOT catch but Windows rejects — the reason
+    /// the sanitiser was unified (code review on ADR 0025): a stored and a regenerated document
+    /// must never diverge in filename safety.
+    /// </summary>
+    [Theory]
+    [InlineData("Angebot A\\B.pdf", "Angebot A_B.pdf")]
+    [InlineData("Re: 2026.pdf", "Re_ 2026.pdf")]
+    [InlineData("x*y?z\".pdf", "x_y_z_.pdf")]
+    [InlineData("tab\there.pdf", "tab_here.pdf")]
+    public void SafeFileName_ReplacesInvalidCharsTheStoredDocumentPathMissed(string documentName, string expected)
+    {
+        Assert.Equal(expected, fds.FdsDocumentNames.SafeFileName(documentName, "X.pdf"));
+    }
+
+    [Theory]
+    [InlineData("Rechnung R2026-0258.pdf")]
+    [InlineData("Wartung 2025/26 R2026-0001.pdf")]
+    [InlineData("a>b|c!d<e/f=g.pdf")]
+    [InlineData("Angebot A\\B: \"x\" <y>|z?*.pdf")]
+    [InlineData("<p></p>")]
+    [InlineData(null)]
+    public void SafeDocumentFileName_MatchesSharedSanitiserForEveryInput(string? documentName)
+    {
+        Assert.Equal(
+            fds.FdsDocumentNames.SafeFileName(documentName, "Rechnung_X.pdf"),
+            IntranetController.SafeDocumentFileName(documentName!, "Rechnung_X.pdf"));
+    }
+
+    [Fact]
+    public void SafeFileName_ReturnsFallbackVerbatim_WhenNothingUsableRemains()
+    {
+        // The fallback is the caller's responsibility and is not sanitised or second-guessed.
+        Assert.Equal("W7VAL", fds.FdsDocumentNames.SafeFileName("<p></p>", "W7VAL"));
+        Assert.Equal("", fds.FdsDocumentNames.SafeFileName("", ""));
+    }
 }

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
+    /// Download filename for a regenerated document — the one shared sanitiser
-    /// invoice title, so it can carry path separators ("Wartung 2025/26") and stray editor markup;
+    /// (<see cref="fds.FdsDocumentNames.SafeFileName"/>) that <c>FdsMfr.GetReportDoc</c> also
-    /// mirrors the cleanup <c>FdsMfr.GetReportDoc</c> applies to stored documents.
+    /// applies to stored documents, so both paths name the same DocumentName identically.
     /// </summary>
-    internal static string SafeDocumentFileName(string documentName, string fallback)
+    internal static string SafeDocumentFileName(string documentName, string fallback) =>
-    {
+        fds.FdsDocumentNames.SafeFileName(documentName, 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;
-    }
 
     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"));

Fuchs/Program.cs

@@ -236,6 +236,38 @@ public class Program
         // calls silently no-op instead of reaching Debug output / ErrorLog.txt.
         OCORE.Logging.Logger = app.Logger;
 
+        // Exceptions that never pass through a request (Do()'s catch-all, PdfPreviewAsync,
+        // UseExceptionHandler) or a hosted service's own try/catch — a faulted fire-and-forget
+        // Task nobody awaited, or a crash on a non-request thread — are otherwise visible only
+        // as a debugger notification or a process exit: they never reach ILogger and therefore
+        // never reach fds__debuglog (ADR 0024). Route them through the app logger so the SQL
+        // sink and ErrorLog.txt both see them. On a terminating crash the fire-and-forget SQL
+        // write may not complete; the synchronous file sink (0003) is the record then.
+        TaskScheduler.UnobservedTaskException += (_, e) =>
+        {
+            app.Logger.LogError(new EventId(0, "Unobserved task exception"), e.Exception,
+                "Unobserved task exception: {Message}", e.Exception.GetBaseException().Message);
+            e.SetObserved();
+        };
+        AppDomain.CurrentDomain.UnhandledException += (_, e) =>
+        {
+            var ex = e.ExceptionObject as Exception;
+            app.Logger.LogCritical(new EventId(0, "Unhandled exception"), ex,
+                "Unhandled exception on a non-request thread (terminating={IsTerminating}): {Message}",
+                e.IsTerminating, ex?.Message ?? e.ExceptionObject?.ToString());
+        };
+
+        // One deliberate Critical entry per application start. Critical is the one level no
+        // provider filters (file sink, console, SQL sink at Warning+), so a fds__debuglog row
+        // with CodeReference 'Application started' proves on every restart that the whole
+        // log pipeline (ADR 0024) is working end to end — and its absence is itself the alarm.
+        // Registered on ApplicationStarted so it is written once the host and every sink are up.
+        app.Lifetime.ApplicationStarted.Register(() =>
+            app.Logger.LogCritical(new EventId(0, "Application started"),
+                "Fuchs started: version={Version} environment={Environment} machine={Machine} pid={Pid}",
+                typeof(Program).Assembly.GetName().Version?.ToString() ?? "?",
+                app.Environment.EnvironmentName, Environment.MachineName, Environment.ProcessId));
+
         if (!app.Environment.IsDevelopment())
         {
             app.UseExceptionHandler("/error");

Fuchs/js/intranet/modules/fis.inv_shared.js

@@ -133,13 +133,27 @@ $inv.pdfPreviewFailed = function (jqXHR, textStatus) {
     alert(($ict.pvf || $t.f1) + (desc !== '' ? '\n' + desc : ''));
 };
 /* postXT never calls `error` for a timeout (it returns early), so the timeout is only
-   observable from `complete`; this builds the complete handler for a preview call. */
+   observable from `complete`; this builds the complete handler for a preview call.
-$inv.pdfPreviewComplete = function (layout) {
+   `wait`, if given, is the "please wait" popup from `$inv.pdfWaitDlg` — it must close on
+   every outcome (success, error, timeout), so `complete` is the only place that reliably
+   covers all three. */
+$inv.pdfPreviewComplete = function (layout, wait) {
     return (jqXHR, textStatus) => {
+        if (wait) { wait.c.trigger('modal_close'); }
         if (layout) { layout.rC('freeze'); }
         if (textStatus === 'timeout') { $inv.pdfPreviewFailed(jqXHR, textStatus); }
     };
 };
+/* A preview render can take anywhere from a couple of seconds to the full 120s timeout (a
+   cold miss regenerates + stores the PDF before rasterising it, ADR 0025); postXT's generic
+   `body.ldng` class has no CSS behind it, so nothing tells the user the click was received.
+   Same popup the MFR data fetch shows (see $inv.cInv2): spinner frame in a modal with the
+   explanation in the footer. Non-exclusive so it can sit on top of an open editor. */
+$inv.pdfWaitDlg = function () {
+    let o = $ocms.dlg($$.dc('rfrm').ldng(1), { exclusive: false, zindex_min: 50 });
+    if (o) { o.ft.rwText($ict.pvw); }
+    return o;
+};
 /* ── Backend-authoritative draft editing controller (ADR 0006/0007) ───────────
    The server holds the truth for an invoice draft in an in-memory session; this
    object seeds it, sends single edits as deltas, and renders the totals footer +
@@ -1563,6 +1577,7 @@ $inv.disp = (id, typ) => {
             break;
     }
     if (u !== '') {
+        let wait = $inv.pdfWaitDlg();
         $ocms.postXT({
             url: $ocms.url(u), data: { id: id || '', typ: 'img' }, timeout: $inv.pdfPreviewTimeout, success: (response) => {
                 let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id;
@@ -1572,11 +1587,12 @@ $inv.disp = (id, typ) => {
                 $ocms.dlg(c, {
                     size: [vhr, Math.round(vw() * 0.88)], zindex_min: 50, form: false, exclusive:false
                 });
-            }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete()
+            }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete(null, wait)
         });
     }
 };
 $inv.jdbn = function (ev) {
+    let wait = $inv.pdfWaitDlg();
     $ocms.postXT({
         url: $ocms.url('inv/rdocn'), data: { name: ev.data.id || '', typ: 'img' }, timeout: $inv.pdfPreviewTimeout, success: (response) => {
             let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id;
@@ -1586,7 +1602,7 @@ $inv.jdbn = function (ev) {
             $ocms.dlg(c, {
                 size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false
             });
-        }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete()
+        }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete(null, wait)
     });
 };
 $inv.sp13b = () => {

Fuchs/js/intranet/modules/fis.inv_txt_de.js

@@ -38,6 +38,7 @@
     pna: 'Diese Seite ist in der Vorschau nicht verfügbar',
     tpe: 'Die Anzahl von {0} Seiten wird aktuell nicht unterstützt',
     eis: 'Der Rechnungsentwurf konnte nicht gespeichert werden.',
+    pvw: 'Das Dokument wird abgerufen und für die Vorschau aufbereitet.\nDer Vorgang kann bis zu 2 Minuten dauern.',
     pvf: 'Die PDF-Vorschau konnte nicht erstellt werden.',
     pvto: 'Der Server hat nicht rechtzeitig geantwortet (Zeitüberschreitung). Bitte versuchen Sie es erneut.',
     pvgone: 'Der Entwurf ist auf dem Server nicht mehr vorhanden (Sitzung abgelaufen). Bitte öffnen Sie den Entwurf erneut.',

Fuchs/wwwroot/web/fis.inv.de.js

@@ -162,6 +162,7 @@ let $ict = {
     pna: 'Diese Seite ist in der Vorschau nicht verfügbar',
     tpe: 'Die Anzahl von {0} Seiten wird aktuell nicht unterstützt',
     eis: 'Der Rechnungsentwurf konnte nicht gespeichert werden.',
+    pvw: 'Das Dokument wird abgerufen und für die Vorschau aufbereitet.\nDer Vorgang kann bis zu 2 Minuten dauern.',
     pvf: 'Die PDF-Vorschau konnte nicht erstellt werden.',
     pvto: 'Der Server hat nicht rechtzeitig geantwortet (Zeitüberschreitung). Bitte versuchen Sie es erneut.',
     pvgone: 'Der Entwurf ist auf dem Server nicht mehr vorhanden (Sitzung abgelaufen). Bitte öffnen Sie den Entwurf erneut.',
@@ -712,13 +713,27 @@ $inv.pdfPreviewFailed = function (jqXHR, textStatus) {
     alert(($ict.pvf || $t.f1) + (desc !== '' ? '\n' + desc : ''));
 };
 /* postXT never calls `error` for a timeout (it returns early), so the timeout is only
-   observable from `complete`; this builds the complete handler for a preview call. */
+   observable from `complete`; this builds the complete handler for a preview call.
-$inv.pdfPreviewComplete = function (layout) {
+   `wait`, if given, is the "please wait" popup from `$inv.pdfWaitDlg` — it must close on
+   every outcome (success, error, timeout), so `complete` is the only place that reliably
+   covers all three. */
+$inv.pdfPreviewComplete = function (layout, wait) {
     return (jqXHR, textStatus) => {
+        if (wait) { wait.c.trigger('modal_close'); }
         if (layout) { layout.rC('freeze'); }
         if (textStatus === 'timeout') { $inv.pdfPreviewFailed(jqXHR, textStatus); }
     };
 };
+/* A preview render can take anywhere from a couple of seconds to the full 120s timeout (a
+   cold miss regenerates + stores the PDF before rasterising it, ADR 0025); postXT's generic
+   `body.ldng` class has no CSS behind it, so nothing tells the user the click was received.
+   Same popup the MFR data fetch shows (see $inv.cInv2): spinner frame in a modal with the
+   explanation in the footer. Non-exclusive so it can sit on top of an open editor. */
+$inv.pdfWaitDlg = function () {
+    let o = $ocms.dlg($$.dc('rfrm').ldng(1), { exclusive: false, zindex_min: 50 });
+    if (o) { o.ft.rwText($ict.pvw); }
+    return o;
+};
 /* ── Backend-authoritative draft editing controller (ADR 0006/0007) ───────────
    The server holds the truth for an invoice draft in an in-memory session; this
    object seeds it, sends single edits as deltas, and renders the totals footer +
@@ -2142,6 +2157,7 @@ $inv.disp = (id, typ) => {
             break;
     }
     if (u !== '') {
+        let wait = $inv.pdfWaitDlg();
         $ocms.postXT({
             url: $ocms.url(u), data: { id: id || '', typ: 'img' }, timeout: $inv.pdfPreviewTimeout, success: (response) => {
                 let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id;
@@ -2151,11 +2167,12 @@ $inv.disp = (id, typ) => {
                 $ocms.dlg(c, {
                     size: [vhr, Math.round(vw() * 0.88)], zindex_min: 50, form: false, exclusive:false
                 });
-            }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete()
+            }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete(null, wait)
         });
     }
 };
 $inv.jdbn = function (ev) {
+    let wait = $inv.pdfWaitDlg();
     $ocms.postXT({
         url: $ocms.url('inv/rdocn'), data: { name: ev.data.id || '', typ: 'img' }, timeout: $inv.pdfPreviewTimeout, success: (response) => {
             let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id;
@@ -2165,7 +2182,7 @@ $inv.jdbn = function (ev) {
             $ocms.dlg(c, {
                 size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false
             });
-        }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete()
+        }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete(null, wait)
     });
 };
 $inv.sp13b = () => {

Fuchs/wwwroot/web/fis.req.de.js

@@ -162,6 +162,7 @@ let $ict = {
     pna: 'Diese Seite ist in der Vorschau nicht verfügbar',
     tpe: 'Die Anzahl von {0} Seiten wird aktuell nicht unterstützt',
     eis: 'Der Rechnungsentwurf konnte nicht gespeichert werden.',
+    pvw: 'Das Dokument wird abgerufen und für die Vorschau aufbereitet.\nDer Vorgang kann bis zu 2 Minuten dauern.',
     pvf: 'Die PDF-Vorschau konnte nicht erstellt werden.',
     pvto: 'Der Server hat nicht rechtzeitig geantwortet (Zeitüberschreitung). Bitte versuchen Sie es erneut.',
     pvgone: 'Der Entwurf ist auf dem Server nicht mehr vorhanden (Sitzung abgelaufen). Bitte öffnen Sie den Entwurf erneut.',
@@ -693,13 +694,27 @@ $inv.pdfPreviewFailed = function (jqXHR, textStatus) {
     alert(($ict.pvf || $t.f1) + (desc !== '' ? '\n' + desc : ''));
 };
 /* postXT never calls `error` for a timeout (it returns early), so the timeout is only
-   observable from `complete`; this builds the complete handler for a preview call. */
+   observable from `complete`; this builds the complete handler for a preview call.
-$inv.pdfPreviewComplete = function (layout) {
+   `wait`, if given, is the "please wait" popup from `$inv.pdfWaitDlg` — it must close on
+   every outcome (success, error, timeout), so `complete` is the only place that reliably
+   covers all three. */
+$inv.pdfPreviewComplete = function (layout, wait) {
     return (jqXHR, textStatus) => {
+        if (wait) { wait.c.trigger('modal_close'); }
         if (layout) { layout.rC('freeze'); }
         if (textStatus === 'timeout') { $inv.pdfPreviewFailed(jqXHR, textStatus); }
     };
 };
+/* A preview render can take anywhere from a couple of seconds to the full 120s timeout (a
+   cold miss regenerates + stores the PDF before rasterising it, ADR 0025); postXT's generic
+   `body.ldng` class has no CSS behind it, so nothing tells the user the click was received.
+   Same popup the MFR data fetch shows (see $inv.cInv2): spinner frame in a modal with the
+   explanation in the footer. Non-exclusive so it can sit on top of an open editor. */
+$inv.pdfWaitDlg = function () {
+    let o = $ocms.dlg($$.dc('rfrm').ldng(1), { exclusive: false, zindex_min: 50 });
+    if (o) { o.ft.rwText($ict.pvw); }
+    return o;
+};
 /* ── Backend-authoritative draft editing controller (ADR 0006/0007) ───────────
    The server holds the truth for an invoice draft in an in-memory session; this
    object seeds it, sends single edits as deltas, and renders the totals footer +
@@ -2123,6 +2138,7 @@ $inv.disp = (id, typ) => {
             break;
     }
     if (u !== '') {
+        let wait = $inv.pdfWaitDlg();
         $ocms.postXT({
             url: $ocms.url(u), data: { id: id || '', typ: 'img' }, timeout: $inv.pdfPreviewTimeout, success: (response) => {
                 let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id;
@@ -2132,11 +2148,12 @@ $inv.disp = (id, typ) => {
                 $ocms.dlg(c, {
                     size: [vhr, Math.round(vw() * 0.88)], zindex_min: 50, form: false, exclusive:false
                 });
-            }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete()
+            }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete(null, wait)
         });
     }
 };
 $inv.jdbn = function (ev) {
+    let wait = $inv.pdfWaitDlg();
     $ocms.postXT({
         url: $ocms.url('inv/rdocn'), data: { name: ev.data.id || '', typ: 'img' }, timeout: $inv.pdfPreviewTimeout, success: (response) => {
             let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id;
@@ -2146,7 +2163,7 @@ $inv.jdbn = function (ev) {
             $ocms.dlg(c, {
                 size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false
             });
-        }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete()
+        }, error: $inv.pdfPreviewFailed, complete: $inv.pdfPreviewComplete(null, wait)
     });
 };
 $inv.sp13b = () => {

Fuchs_DataService/FdsMfr.cs

@@ -205,9 +205,12 @@ public class FdsMfr : IFdsMfr
             if (fl != null)
             {
                 file = fl;
-                string safeName = fln.Replace("<p>", "").Replace("</p>", "").Replace("=", "_")
+                // Same sanitiser as the regenerate-on-miss path (ADR 0025) so a stored and a
-                    .Replace(">", "_").Replace("|", "_").Replace("!", "_").Replace("<", "_").Replace("/", "_");
+                // regenerated document with the same DocumentName download under the same name.
-                return new FileInfo(Path.GetTempPath() + safeName);
+                // Fallback to the report id: an empty DocumentName used to yield the temp-dir
+                // segment ("Temp") as the download name.
+                string safeName = FdsDocumentNames.SafeFileName(fln, reportid);
+                return new FileInfo(Path.Combine(Path.GetTempPath(), safeName));
             }
         }
         return null;

Fuchs_DataService/FdsShared.cs

@@ -40,6 +40,33 @@ public static class FdsConfig
         Current["Fds:MFR_host"] ?? "";
 }
 
+/// <summary>
+/// Download-filename sanitising shared by every path that hands a document to the browser —
+/// stored documents (<see cref="FdsMfr.GetReportDoc"/>) and documents regenerated on a miss
+/// (<c>IntranetController.HandleReportDoc</c>, ADR 0025) — so both produce the same name for the
+/// same DocumentName. DocumentName is derived from the user-typed invoice title, so it can carry
+/// path separators ("Wartung 2025/26"), stray editor markup and characters Windows rejects.
+/// </summary>
+public static class FdsDocumentNames
+{
+    // '=' and '!' are legal filename characters, but the stored-document path replaced them
+    // long before the regenerate path existed; kept so unifying the two never loosens either.
+    private static readonly char[] Replaced =
+        [.. Path.GetInvalidFileNameChars(), '=', '!'];
+
+    /// <param name="documentName">Raw DocumentName (may be null, empty, or wrapped in &lt;p&gt;).</param>
+    /// <param name="fallback">Used when nothing usable remains after cleanup.</param>
+    public static string SafeFileName(string? documentName, string fallback)
+    {
+        string name = (documentName ?? "").Replace("<p>", "").Replace("</p>", "").Trim();
+        if (name.Length == 0) return fallback;
+        foreach (char c in Replaced)
+            name = name.Replace(c, '_');
+        name = name.Trim();
+        return name.Length == 0 ? fallback : name;
+    }
+}
+
 internal static class FdsShared
 {
     internal static string FDSConnectionString() => FdsConfig.FDSConnectionString();

Fuchs_DataService/Fuchs_DataService.xml

@@ -37,5 +37,18 @@
             which <c>Program.cs</c> calls once at startup before any <see cref="T:fds.FdsMfr"/> use.
             </summary>
         </member>
+        <member name="T:fds.FdsDocumentNames">
+            <summary>
+            Download-filename sanitising shared by every path that hands a document to the browser —
+            stored documents (<see cref="M:fds.FdsMfr.GetReportDoc(System.Byte[]@,System.String,System.Boolean)"/>) and documents regenerated on a miss
+            (<c>IntranetController.HandleReportDoc</c>, ADR 0025) — so both produce the same name for the
+            same DocumentName. DocumentName is derived from the user-typed invoice title, so it can carry
+            path separators ("Wartung 2025/26"), stray editor markup and characters Windows rejects.
+            </summary>
+        </member>
+        <member name="M:fds.FdsDocumentNames.SafeFileName(System.String,System.String)">
+            <param name="documentName">Raw DocumentName (may be null, empty, or wrapped in &lt;p&gt;).</param>
+            <param name="fallback">Used when nothing usable remains after cleanup.</param>
+        </member>
     </members>
 </doc>

global.json

@@ -0,0 +1,5 @@
+{
+  "test": {
+    "runner": "Microsoft.Testing.Platform"
+  }
+}