diff --git a/SharepointToolbox.Tests/Localization/LocaleCompletenessTests.cs b/SharepointToolbox.Tests/Localization/LocaleCompletenessTests.cs
new file mode 100644
index 0000000..c3b337d
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+++ b/SharepointToolbox.Tests/Localization/LocaleCompletenessTests.cs
@@ -0,0 +1,84 @@
+using System.Collections;
+using System.Globalization;
+using System.Resources;
+using SharepointToolbox.Localization;
+
+namespace SharepointToolbox.Tests.Localization;
+
+[Trait("Category", "Unit")]
+public class LocaleCompletenessTests
+{
+    /// <summary>
+    /// Verifies every EN key in Strings.resx has a non-empty, non-bracketed FR translation.
+    /// </summary>
+    [Fact]
+    public void AllEnKeys_HaveNonEmptyFrTranslation()
+    {
+        var rm = new ResourceManager("SharepointToolbox.Localization.Strings", typeof(Strings).Assembly);
+        var enResourceSet = rm.GetResourceSet(CultureInfo.InvariantCulture, true, true);
+        Assert.NotNull(enResourceSet);
+
+        var frCulture = new CultureInfo("fr");
+        var failures = new List<string>();
+
+        foreach (DictionaryEntry entry in enResourceSet)
+        {
+            var key = entry.Key?.ToString();
+            if (string.IsNullOrEmpty(key)) continue;
+
+            var frValue = rm.GetString(key, frCulture);
+            if (string.IsNullOrWhiteSpace(frValue))
+            {
+                failures.Add($"  [{key}]: null or whitespace");
+            }
+            else if (frValue.StartsWith("[", StringComparison.Ordinal))
+            {
+                failures.Add($"  [{key}]: bracketed fallback — '{frValue}'");
+            }
+        }
+
+        Assert.True(failures.Count == 0,
+            $"The following {failures.Count} key(s) are missing or invalid in Strings.fr.resx:\n" +
+            string.Join("\n", failures));
+    }
+
+    /// <summary>
+    /// Spot-checks 5 keys that must contain diacritics after Plan 02 fixes.
+    /// This test FAILS until Plan 02 corrects the FR translations.
+    /// </summary>
+    [Fact]
+    public void FrStrings_ContainExpectedDiacritics()
+    {
+        var rm = new ResourceManager("SharepointToolbox.Localization.Strings", typeof(Strings).Assembly);
+        var frCulture = new CultureInfo("fr");
+        var failures = new List<string>();
+
+        void CheckDiacritic(string key, char expectedChar)
+        {
+            var value = rm.GetString(key, frCulture);
+            if (value == null || !value.Contains(expectedChar))
+            {
+                failures.Add($"  [{key}] = '{value ?? "(null)"}' — expected to contain '{expectedChar}'");
+            }
+        }
+
+        // Déplacer must contain é (currently "Deplacer")
+        CheckDiacritic("transfer.mode.move", 'é');
+
+        // Créer les sites must contain é (currently "Creer les sites")
+        CheckDiacritic("bulksites.execute", 'é');
+
+        // Modèles enregistrés must contain è (currently "Modeles enregistres")
+        CheckDiacritic("templates.list", 'è');
+
+        // Terminé : {0} réussis, {1} échoués must contain é (currently "Termine : ...")
+        CheckDiacritic("bulk.result.success", 'é');
+
+        // Bibliothèque cible must contain è (currently "Bibliotheque cible")
+        CheckDiacritic("folderstruct.library", 'è');
+
+        Assert.True(failures.Count == 0,
+            $"The following {failures.Count} key(s) are missing expected diacritics in Strings.fr.resx " +
+            $"(fix in Plan 02):\n" + string.Join("\n", failures));
+    }
+}