Fix PostIt attachment links to match uploaded filenames

Apply the shared filename filter before URL encoding, preserve escaped URLs and original link labels, and add regression coverage for accented and spaced filenames. Update the changelog.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CHANGELOG.md

@@ -24,6 +24,10 @@
 
 ### Fixed
 
+* [PostIt] Les liens Markdown des pièces jointes utilisent désormais
+  le même filtre de nom que l'upload serveur, avant l'encodage URL.
+  Le libellé conserve le nom original, notamment ses accents.
+
 * [Yavsc.Abstract][Yavsc.Blogs] Encodage des caractères non supportés
   dans les noms de fichiers téléversés avec `_` au lieu de `#`, pour
   éviter les fragments d'URL et permettre le téléchargement via les

src/PostIt/PostIt.Tests/BlogAttachmentLinkTests.cs

@@ -20,8 +20,13 @@ namespace PostIt.Tests;
 /// </summary>
 public class BlogAttachmentLinkTests
 {
-    [Fact]
-    public async Task Save_with_attachment_appends_absolute_link_derived_from_the_oidc_authority()
+    [Theory]
+    [InlineData("note.txt", "note.txt")]
+    [InlineData("INSC_E03686381_SCHNEIDER_000113378AA__Troisi\u00e8me__.PDF",
+        "INSC_E03686381_SCHNEIDER_000113378AA__Troisi_232me__.PDF")]
+    [InlineData("rapport final.pdf", "rapport%20final.pdf")]
+    public async Task Save_with_attachment_appends_absolute_link_derived_from_the_oidc_authority(
+        string originalName, string urlName)
     {
         const string authority = "https://idp.example.test";
 
@@ -53,7 +58,7 @@ public class BlogAttachmentLinkTests
         vm.DraftTitle = "Après";
         vm.DraftArticle = "Contenu modifié.";
         vm.DraftAttachments.Add(new BlogUploadFile(
-            "note.txt",
+            originalName,
             System.Text.Encoding.UTF8.GetBytes("payload test"),
             "text/plain"));
 
@@ -68,12 +73,14 @@ public class BlogAttachmentLinkTests
         var sent = Assert.IsType<System.Func<HttpContent>>(linkPut.body);
         var multipartContent = Assert.IsType<MultipartFormDataContent>(sent());
 
-        var expectedUrl = $"{authority}/files/tester/blogs/42/note.txt";
-        var sentStringContent =  multipartContent.First() as StringContent ;
+        var expectedUrl = $"{authority}/files/tester/blogs/42/{urlName}";
+        var sentStringContent = Assert.IsType<StringContent>(multipartContent.First());
 
         var sentString = await sentStringContent.ReadAsStringAsync(TestContext.Current.CancellationToken);
-        Assert.Contains($"- [note.txt]({expectedUrl})", sentString);
+        using var document = System.Text.Json.JsonDocument.Parse(sentString);
+        var article = document.RootElement.GetProperty("article").GetString();
+        Assert.Contains($"- [{originalName}]({expectedUrl})", article);
         // The regression shape: a relative, authority-less link.
-        Assert.DoesNotContain("](/files/", sentString);
+        Assert.DoesNotContain("](/files/", article);
     }
 }

src/PostIt/PostIt/ViewModels/Blogs/BlogsViewModel.cs

@@ -10,6 +10,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Yavsc.Blogspot;
 using Yavsc.Api.Client;
 using Yavsc.Abstract.Files;
+using Yavsc.Server.Helpers;
 using AvaloniaEdit.Document;
 
 namespace PostIt.ViewModels;
@@ -611,7 +612,8 @@ public partial class BlogsViewModel : ViewModelBase, IActionStatusViewModel
 
         foreach (var attachment in attachments)
         {
-            var relativePath = $"{EscapePathSegment(ownerSegment)}/blogs/{post.Id}/{EscapePathSegment(attachment.FileName)}";
+            var storedName = AbstractFileSystemHelpers.FilterFileName(attachment.FileName);
+            var relativePath = $"{EscapePathSegment(ownerSegment)}/blogs/{post.Id}/{EscapePathSegment(storedName)}";
             var fileUrl = ResolveUserFileUrl(relativePath);
             var markdownLine = $"- [{attachment.FileName}]({fileUrl})";
 
@@ -636,7 +638,7 @@ public partial class BlogsViewModel : ViewModelBase, IActionStatusViewModel
         if (!string.IsNullOrWhiteSpace(authority)
             && Uri.TryCreate(authority, UriKind.Absolute, out var baseUri))
         {
-            return FileServerUrlHelpers.GetUserFilesUri(baseUri, relativePath).ToString();
+            return FileServerUrlHelpers.GetUserFilesUri(baseUri, relativePath).AbsoluteUri;
         }
 
         return $"{Yavsc.Constants.UserFilesPath}/{relativePath}";