diff --git a/docs/features/library.md b/docs/features/library.md
index 7a4eaa52..38833d16 100644
--- a/docs/features/library.md
+++ b/docs/features/library.md
@@ -26,7 +26,20 @@ Directory resolution (`read_dir` + read + blake3 per directory, potentially hund
 
 Because that walk can take seconds, the candidate list is a snapshot that may be stale by the time it is written. The update is therefore a compare-and-swap that also re-asserts the source allowlist (`link_folder_cover_if_eligible`): an album whose cover changed mid-walk — the user uploaded one, or a concurrent scan resolved a fresher sidecar — is left alone, and the count of refreshed covers comes from `rows_affected` so a skipped album never inflates the scan summary.
 
-A tag edit that rewrites the audio file _is_ already detected, since it moves that file's mtime — this pass is specifically about the sidecar case.
+A tag edit that rewrites the audio file is normally detected, since it moves that file's mtime — this pass is specifically about the sidecar case. **But that is not guaranteed**: taggers commonly offer to preserve the modification date (Mp3tag ships that behaviour), and an ID3 rewrite often fits in the existing padding, so `size` doesn't move either. The file then looks untouched to the fast path and its new tags are never read — reported as issue #457 for a batch of genre edits.
+
+### Deep rescan
+
+A **deep rescan** bypasses `(mtime, size)` entirely and re-hashes + re-reads every file. It is the escape hatch for exactly the case above, and it is opt-in because it costs a full re-read of the library.
+
+Two entry points, in different places:
+
+- **per folder** — the magnifier button on a folder row, under **My music → Folders** (`scan_folder` with `deep: true`). Appears on row hover;
+- **whole library** — the second button next to Rescan in the **My music header**, so it is reachable from any tab, not just Folders (`rescan_library` with `deep: true`). Added in issue #457: until then the bypass existed per folder only, so the library-wide button users actually reach for could never see mtime-preserving edits.
+
+Both are mutually exclusive with each other and with a plain rescan — `scan_folder_inner` writes, and SQLite takes one writer at a time.
+
+Note the interaction with **Split this artist** below: a deep rescan re-reads tags authoritatively and will undo an in-place split, since it no longer sees the split as deliberate.
 
 ## Audio analysis
 
diff --git a/src-tauri/crates/app/src/commands/library.rs b/src-tauri/crates/app/src/commands/library.rs
index 6febf031..94f629ed 100644
--- a/src-tauri/crates/app/src/commands/library.rs
+++ b/src-tauri/crates/app/src/commands/library.rs
@@ -320,7 +320,17 @@ pub async fn rescan_library(
     app: tauri::AppHandle,
     state: tauri::State<'_, AppState>,
     library_id: i64,
+    // Same escape hatch `scan_folder` has carried since issue #366:
+    // an external tagger can rewrite tags while preserving the file's
+    // mtime (Mp3tag's "preserve modification time" is on by default),
+    // and the `(mtime, size)` fast path then skips the file forever.
+    // Until this existed the bypass was reachable per folder only, so
+    // the library-wide button users actually reach for could never see
+    // those edits (issue #457). Opt-in: a deep pass re-hashes and
+    // re-reads every file.
+    deep: Option<bool>,
 ) -> AppResult<RescanSummary> {
+    let deep = deep.unwrap_or(false);
     let pool = state.require_profile_pool().await?;
     let profile_id = state.require_profile_id().await?;
     let artwork_dir = state.paths.profile_artwork_dir(profile_id);
@@ -334,7 +344,7 @@ pub async fn rescan_library(
     };
 
     for folder_id in folder_ids {
-        match scan_folder_inner(&pool, &artwork_dir, folder_id, Some(&app), false).await {
+        match scan_folder_inner(&pool, &artwork_dir, folder_id, Some(&app), deep).await {
             Ok(summary) => {
                 total.folders += 1;
                 let ScanSummary {
diff --git a/src/components/common/ScanProgressToast.tsx b/src/components/common/ScanProgressToast.tsx
index 5a3ce343..3de3d439 100644
--- a/src/components/common/ScanProgressToast.tsx
+++ b/src/components/common/ScanProgressToast.tsx
@@ -1,7 +1,7 @@
 import { useEffect, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { listen } from "@tauri-apps/api/event";
-import { FolderSearch, X, CheckCircle2 } from "lucide-react";
+import { FolderSearch, X, CheckCircle2, AlertTriangle } from "lucide-react";
 
 interface ScanProgress {
   folder_id: number;
@@ -64,10 +64,13 @@ export function ScanProgressToast() {
 
   if (progress == null || dismissed) return null;
 
-  const { current, total, added, updated, skipped, done, current_dir } =
+  const { current, total, added, updated, skipped, errors, done, current_dir } =
     progress;
   const percent =
     total > 0 ? Math.min(100, Math.round((current / total) * 100)) : 0;
+  // A finished scan that hit per-file failures. The backend reports it
+  // as done regardless, so this is the only signal the user gets.
+  const partial = done && errors > 0;
   // Show the last two path segments (…/Parent/Album) so the user sees the
   // scan walking through folders without the toast overflowing on a deep
   // absolute path; the full path rides in the title tooltip. (#430)
@@ -84,22 +87,39 @@ export function ScanProgressToast() {
       <div className="flex items-start gap-3">
         <div
           className={`shrink-0 w-9 h-9 rounded-full flex items-center justify-center ${
-            done
-              ? "bg-emerald-500/15 text-emerald-500"
-              : "bg-emerald-500/10 text-emerald-500"
+            partial
+              ? "bg-amber-500/15 text-amber-500"
+              : done
+                ? "bg-emerald-500/15 text-emerald-500"
+                : "bg-emerald-500/10 text-emerald-500"
           }`}
         >
-          {done ? (
+          {partial ? (
+            <AlertTriangle size={18} />
+          ) : done ? (
             <CheckCircle2 size={18} />
           ) : (
             <FolderSearch size={18} className="animate-pulse" />
           )}
         </div>
         <div className="flex-1 min-w-0">
-          <div className="text-sm font-semibold text-zinc-900 dark:text-zinc-100">
-            {done
-              ? t("scanProgress.doneTitle")
-              : t("scanProgress.runningTitle")}
+          {/* A scan that hit errors must not read as a plain success:
+              the backend reports it as complete either way, so the
+              failure count takes the headline (and the icon goes amber)
+              rather than trailing a green "Scan complete". The
+              added/updated/skipped line stays below as context. */}
+          <div
+            className={`text-sm font-semibold ${
+              partial
+                ? "text-amber-700 dark:text-amber-500"
+                : "text-zinc-900 dark:text-zinc-100"
+            }`}
+          >
+            {partial
+              ? t("scanProgress.doneErrors", { count: errors })
+              : done
+                ? t("scanProgress.doneTitle")
+                : t("scanProgress.runningTitle")}
           </div>
           <div className="text-xs text-zinc-500 dark:text-zinc-400 mt-0.5">
             {done
diff --git a/src/components/views/LibraryView.tsx b/src/components/views/LibraryView.tsx
index a7a76f51..33fdaed4 100644
--- a/src/components/views/LibraryView.tsx
+++ b/src/components/views/LibraryView.tsx
@@ -14,6 +14,7 @@ import {
   Tags,
   Folder,
   RefreshCcw,
+  FileSearch,
   Clock,
   LayoutList,
   AlignJustify,
@@ -149,12 +150,23 @@ export function LibraryView({
   } = usePlaylist();
   const [isImporting, setIsImporting] = useState(false);
   const [isRescanning, setIsRescanning] = useState(false);
+  // Separate from `isRescanning` so the two buttons disable each other
+  // without either claiming the other's spinner.
+  const [isDeepRescanning, setIsDeepRescanning] = useState(false);
   // Which folder a deep rescan (issue #366) is currently running against,
   // if any — drives the spinner on that row's action only, since it's a
   // per-folder action rather than the global "Rescan" button above.
   const [deepRescanFolderId, setDeepRescanFolderId] = useState<number | null>(
     null,
   );
+
+  // Any scan in flight, whichever control started it. `scan_folder_inner`
+  // is a writer and SQLite takes one writer at a time, so a folder-level
+  // deep pass and a library-wide one must not overlap — before this, the
+  // global buttons only guarded against each other and left the
+  // per-folder button free to start a second concurrent scan.
+  const isAnyRescanActive =
+    isRescanning || isDeepRescanning || deepRescanFolderId != null;
   const [isCreatePlaylistModalOpen, setIsCreatePlaylistModalOpen] =
     useState(false);
   // When the create-playlist modal is opened from a popover's "+ New
@@ -430,23 +442,75 @@ export function LibraryView({
     }
   };
 
+  const handleDeepRescanLibrary = async () => {
+    // Whole-library counterpart of the per-folder deep rescan below.
+    // Same rationale (issue #457): the normal pass trusts (mtime, size)
+    // and therefore cannot see tags an external editor rewrote while
+    // preserving mtime.
+    if (isAnyRescanActive) return;
+    setIsDeepRescanning(true);
+    try {
+      // Per-library error handling: one unreadable library (a drive
+      // that went away, a permission change) must not strand the ones
+      // after it — the user asked for a full pass.
+      //
+      // A rejected promise is only half the story: `rescan_library`
+      // swallows per-folder failures into `summary.errors` and still
+      // resolves, so a partially failed pass looks identical to a clean
+      // one unless the summary is inspected.
+      let failedFolders = 0;
+      for (const lib of libraries) {
+        try {
+          const summary = await rescanLibrary(lib.id, true);
+          failedFolders += summary.errors;
+        } catch (err) {
+          console.error(
+            `[LibraryView] deep rescan failed for library ${lib.id}`,
+            err,
+          );
+        }
+      }
+      if (failedFolders > 0) {
+        console.warn(
+          `[LibraryView] deep rescan finished with ${failedFolders} folder error(s)`,
+        );
+      }
+    } finally {
+      setIsDeepRescanning(false);
+    }
+  };
+
   const handleRescan = async () => {
-    if (isRescanning) return;
+    if (isAnyRescanActive) return;
     setIsRescanning(true);
     try {
-      // Rescan every library the profile owns.
+      // Rescan every library the profile owns, one failure at a time —
+      // same reasoning, and the same summary caveat, as the deep pass
+      // above.
+      let failedFolders = 0;
       for (const lib of libraries) {
-        await rescanLibrary(lib.id);
+        try {
+          const summary = await rescanLibrary(lib.id);
+          failedFolders += summary.errors;
+        } catch (err) {
+          console.error(
+            `[LibraryView] rescan failed for library ${lib.id}`,
+            err,
+          );
+        }
+      }
+      if (failedFolders > 0) {
+        console.warn(
+          `[LibraryView] rescan finished with ${failedFolders} folder error(s)`,
+        );
       }
-    } catch (err) {
-      console.error("[LibraryView] rescan failed", err);
     } finally {
       setIsRescanning(false);
     }
   };
 
   const handleDeepRescanFolder = async (folderId: number) => {
-    if (deepRescanFolderId != null) return;
+    if (isAnyRescanActive) return;
     setDeepRescanFolderId(folderId);
     try {
       await scanFolder(folderId, true);
@@ -511,7 +575,7 @@ export function LibraryView({
               <button
                 type="button"
                 onClick={handleRescan}
-                disabled={libraries.length === 0 || isRescanning}
+                disabled={libraries.length === 0 || isAnyRescanActive}
                 aria-label={t("library.actions.rescan")}
                 aria-busy={isRescanning}
                 className="p-2 rounded-lg transition-colors hover:bg-zinc-100 text-zinc-500 hover:text-zinc-800 dark:hover:bg-zinc-700 dark:text-zinc-400 dark:hover:text-white disabled:opacity-50 disabled:cursor-not-allowed"
@@ -522,6 +586,31 @@ export function LibraryView({
                 />
               </button>
             </Tooltip>
+            {/* Deep pass, mirroring the per-folder button in the folder
+                list. Separate control rather than a modifier on the one
+                above: it is markedly slower, so it should be chosen, not
+                triggered by accident. */}
+            <Tooltip
+              label={
+                isDeepRescanning
+                  ? t("library.actions.deepRescanning")
+                  : t("library.actions.deepRescan")
+              }
+            >
+              <button
+                type="button"
+                onClick={handleDeepRescanLibrary}
+                disabled={libraries.length === 0 || isAnyRescanActive}
+                aria-label={t("library.actions.deepRescan")}
+                aria-busy={isDeepRescanning}
+                className="p-2 rounded-lg transition-colors hover:bg-zinc-100 text-zinc-500 hover:text-zinc-800 dark:hover:bg-zinc-700 dark:text-zinc-400 dark:hover:text-white disabled:opacity-50 disabled:cursor-not-allowed"
+              >
+                <FileSearch
+                  size={18}
+                  className={isDeepRescanning ? "animate-pulse" : ""}
+                />
+              </button>
+            </Tooltip>
           </div>
         </div>
       </div>
@@ -764,6 +853,7 @@ export function LibraryView({
               }}
               onDeepRescan={handleDeepRescanFolder}
               deepRescanFolderId={deepRescanFolderId}
+              isAnyRescanActive={isAnyRescanActive}
               onToggleWatched={(folderId, enable) => {
                 // Optimistic flip — the watcher hookup is fire-and-
                 // forget on the backend so the UI shouldn't block on it.
@@ -2244,6 +2334,10 @@ interface FolderListProps {
   onDeepRescan: (folderId: number) => void;
   /** The folder a deep rescan is currently running against, if any. */
   deepRescanFolderId: number | null;
+  /** True while ANY scan is running — a library-wide pass included, not
+   *  just a folder one. SQLite takes a single writer, so this row's
+   *  button has to stand down for the global controls too. */
+  isAnyRescanActive: boolean;
 }
 
 function FolderList({
@@ -2257,6 +2351,7 @@ function FolderList({
   onRemove,
   onDeepRescan,
   deepRescanFolderId,
+  isAnyRescanActive,
 }: FolderListProps) {
   const [openMenuFolderId, setOpenMenuFolderId] = useState<number | null>(null);
   // Two-step delete: first click arms the confirm state, second click
@@ -2392,7 +2487,7 @@ function FolderList({
                   e.stopPropagation();
                   onDeepRescan(folder.id);
                 }}
-                disabled={deepRescanFolderId != null}
+                disabled={isAnyRescanActive}
                 aria-label={t("library.folderList.deepRescan")}
                 aria-busy={deepRescanFolderId === folder.id}
                 className={`p-1.5 rounded-full transition-colors text-zinc-400 hover:text-zinc-800 dark:hover:text-white hover:bg-zinc-100 dark:hover:bg-zinc-700 disabled:opacity-50 ${
diff --git a/src/contexts/LibraryContext.tsx b/src/contexts/LibraryContext.tsx
index 714ada38..79eff627 100644
--- a/src/contexts/LibraryContext.tsx
+++ b/src/contexts/LibraryContext.tsx
@@ -191,8 +191,8 @@ export function LibraryProvider({ children }: { children: ReactNode }) {
   );
 
   const rescanLibrary = useCallback(
-    async (libraryId: number) => {
-      const summary = await apiRescanLibrary(libraryId);
+    async (libraryId: number, deep = false) => {
+      const summary = await apiRescanLibrary(libraryId, deep);
       await refresh();
       return summary;
     },
diff --git a/src/hooks/useLibrary.ts b/src/hooks/useLibrary.ts
index 85e954d8..f5a835f8 100644
--- a/src/hooks/useLibrary.ts
+++ b/src/hooks/useLibrary.ts
@@ -38,7 +38,9 @@ interface LibraryContextValue {
   /** Permanently delete a library and everything it owns. */
   deleteLibrary: (libraryId: number) => Promise<void>;
   /** Re-walk every folder of the library and sync the DB with disk. */
-  rescanLibrary: (libraryId: number) => Promise<RescanSummary>;
+  /** `deep` re-reads every file instead of trusting the (mtime, size)
+   *  fast path — see `rescanLibrary` in `lib/tauri/library`. */
+  rescanLibrary: (libraryId: number, deep?: boolean) => Promise<RescanSummary>;
   /**
    * Register a folder inside a library and immediately scan it. Returns the
    * summary so the UI can surface counts to the user.
diff --git a/src/i18n/locales/ar.json b/src/i18n/locales/ar.json
index bafa51d5..376cf868 100644
--- a/src/i18n/locales/ar.json
+++ b/src/i18n/locales/ar.json
@@ -430,7 +430,9 @@
       "edit": "تعديل المكتبة",
       "delete": "حذف المكتبة",
       "deleteConfirm": "انقر مرة أخرى للتأكيد",
-      "importing": "جارٍ الاستيراد…"
+      "importing": "جارٍ الاستيراد…",
+      "deepRescan": "فحص عميق (يعيد قراءة كل ملف، أبطأ)",
+      "deepRescanning": "جارٍ الفحص العميق…"
     },
     "changeCover": "تغيير الغلاف",
     "searchDeezer": "البحث في Deezer",
@@ -2129,7 +2131,13 @@
     "runningSubtitle": "{{current}} / {{total}} ملف",
     "doneTitle": "اكتمل الفحص",
     "doneSubtitle": "{{added}} مضاف · {{updated}} محدّث · {{skipped}} متخطّى",
-    "scanningIn": "جارٍ فحص {{dir}}"
+    "scanningIn": "جارٍ فحص {{dir}}",
+    "doneErrors_zero": "لم يفشل أي ملف",
+    "doneErrors_one": "فشل ملف واحد",
+    "doneErrors_two": "فشل ملفان",
+    "doneErrors_few": "فشل {{count}} ملفات",
+    "doneErrors_many": "فشل {{count}} ملفًا",
+    "doneErrors_other": "فشل {{count}} ملف"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/de.json b/src/i18n/locales/de.json
index 64a4dc40..ac6abf42 100644
--- a/src/i18n/locales/de.json
+++ b/src/i18n/locales/de.json
@@ -389,7 +389,9 @@
       "edit": "Bibliothek bearbeiten",
       "delete": "Bibliothek löschen",
       "deleteConfirm": "Zur Bestätigung erneut klicken",
-      "importing": "Wird importiert…"
+      "importing": "Wird importiert…",
+      "deepRescan": "Tiefen-Scan (liest jede Datei neu, langsamer)",
+      "deepRescanning": "Tiefen-Scan läuft…"
     },
     "changeCover": "Cover ändern",
     "searchDeezer": "Auf Deezer suchen",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} Dateien",
     "doneTitle": "Scan abgeschlossen",
     "doneSubtitle": "{{added}} hinzugefügt · {{updated}} aktualisiert · {{skipped}} übersprungen",
-    "scanningIn": "Durchsuche {{dir}}"
+    "scanningIn": "Durchsuche {{dir}}",
+    "doneErrors_one": "{{count}} Datei fehlgeschlagen",
+    "doneErrors_other": "{{count}} Dateien fehlgeschlagen"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/en.json b/src/i18n/locales/en.json
index b7548a1c..a5593180 100644
--- a/src/i18n/locales/en.json
+++ b/src/i18n/locales/en.json
@@ -389,7 +389,9 @@
       "edit": "Edit the library",
       "delete": "Delete the library",
       "deleteConfirm": "Click again to confirm",
-      "importing": "Importing…"
+      "importing": "Importing…",
+      "deepRescan": "Deep rescan (re-reads every file, slower)",
+      "deepRescanning": "Deep rescan in progress…"
     },
     "changeCover": "Change cover",
     "searchDeezer": "Search Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} files",
     "doneTitle": "Scan complete",
     "doneSubtitle": "{{added}} added · {{updated}} updated · {{skipped}} skipped",
-    "scanningIn": "Scanning {{dir}}"
+    "scanningIn": "Scanning {{dir}}",
+    "doneErrors_one": "{{count}} file failed",
+    "doneErrors_other": "{{count}} files failed"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/es.json b/src/i18n/locales/es.json
index 31b2ea3f..12dc13f0 100644
--- a/src/i18n/locales/es.json
+++ b/src/i18n/locales/es.json
@@ -389,7 +389,9 @@
       "edit": "Editar la biblioteca",
       "delete": "Eliminar la biblioteca",
       "deleteConfirm": "Haz clic de nuevo para confirmar",
-      "importing": "Importando…"
+      "importing": "Importando…",
+      "deepRescan": "Reanálisis profundo (relee todos los archivos, más lento)",
+      "deepRescanning": "Reanálisis profundo en curso…"
     },
     "changeCover": "Cambiar portada",
     "searchDeezer": "Buscar en Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} archivos",
     "doneTitle": "Escaneo completado",
     "doneSubtitle": "{{added}} añadidos · {{updated}} actualizados · {{skipped}} omitidos",
-    "scanningIn": "Analizando {{dir}}"
+    "scanningIn": "Analizando {{dir}}",
+    "doneErrors_one": "{{count}} archivo con error",
+    "doneErrors_other": "{{count}} archivos con error"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/fr.json b/src/i18n/locales/fr.json
index 9748d229..79232622 100644
--- a/src/i18n/locales/fr.json
+++ b/src/i18n/locales/fr.json
@@ -389,7 +389,9 @@
       "changeArtwork": "Changer la pochette (bientôt)",
       "edit": "Modifier la bibliothèque",
       "delete": "Supprimer la bibliothèque",
-      "deleteConfirm": "Cliquez à nouveau pour confirmer"
+      "deleteConfirm": "Cliquez à nouveau pour confirmer",
+      "deepRescan": "Rescan approfondi (relit tous les fichiers, plus lent)",
+      "deepRescanning": "Rescan approfondi en cours…"
     },
     "changeCover": "Changer la pochette",
     "searchDeezer": "Recherche Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} fichiers",
     "doneTitle": "Analyse terminée",
     "doneSubtitle": "{{added}} ajoutés · {{updated}} mis à jour · {{skipped}} ignorés",
-    "scanningIn": "Analyse de {{dir}}"
+    "scanningIn": "Analyse de {{dir}}",
+    "doneErrors_one": "{{count}} fichier en échec",
+    "doneErrors_other": "{{count}} fichiers en échec"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/hi.json b/src/i18n/locales/hi.json
index 2355c242..03da125e 100644
--- a/src/i18n/locales/hi.json
+++ b/src/i18n/locales/hi.json
@@ -389,7 +389,9 @@
       "edit": "लाइब्रेरी संपादित करें",
       "delete": "लाइब्रेरी हटाएँ",
       "deleteConfirm": "पुष्टि करने के लिए फिर से क्लिक करें",
-      "importing": "इम्पोर्ट हो रहा है…"
+      "importing": "इम्पोर्ट हो रहा है…",
+      "deepRescan": "गहन पुनःस्कैन (हर फ़ाइल दोबारा पढ़ता है, धीमा)",
+      "deepRescanning": "गहन पुनःस्कैन जारी…"
     },
     "changeCover": "कवर बदलें",
     "searchDeezer": "Deezer में खोजें",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} फ़ाइलें",
     "doneTitle": "स्कैन पूर्ण",
     "doneSubtitle": "{{added}} जोड़े · {{updated}} अपडेट · {{skipped}} छोड़े",
-    "scanningIn": "{{dir}} स्कैन हो रहा है"
+    "scanningIn": "{{dir}} स्कैन हो रहा है",
+    "doneErrors_one": "{{count}} फ़ाइल विफल",
+    "doneErrors_other": "{{count}} फ़ाइलें विफल"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/id.json b/src/i18n/locales/id.json
index d79e3b74..e020f90b 100644
--- a/src/i18n/locales/id.json
+++ b/src/i18n/locales/id.json
@@ -389,7 +389,9 @@
       "edit": "Sunting pustaka",
       "delete": "Hapus pustaka",
       "deleteConfirm": "Klik lagi untuk konfirmasi",
-      "importing": "Mengimpor…"
+      "importing": "Mengimpor…",
+      "deepRescan": "Pemindaian mendalam (membaca ulang semua berkas, lebih lambat)",
+      "deepRescanning": "Pemindaian mendalam berlangsung…"
     },
     "changeCover": "Ganti sampul",
     "searchDeezer": "Cari di Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} berkas",
     "doneTitle": "Pemindaian selesai",
     "doneSubtitle": "{{added}} ditambahkan · {{updated}} diperbarui · {{skipped}} dilewati",
-    "scanningIn": "Memindai {{dir}}"
+    "scanningIn": "Memindai {{dir}}",
+    "doneErrors_one": "{{count}} berkas gagal",
+    "doneErrors_other": "{{count}} berkas gagal"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/it.json b/src/i18n/locales/it.json
index 21cf7dc4..a7237f0b 100644
--- a/src/i18n/locales/it.json
+++ b/src/i18n/locales/it.json
@@ -389,7 +389,9 @@
       "edit": "Modifica la libreria",
       "delete": "Elimina la libreria",
       "deleteConfirm": "Clicca di nuovo per confermare",
-      "importing": "Importazione…"
+      "importing": "Importazione…",
+      "deepRescan": "Riscansione approfondita (rilegge tutti i file, più lenta)",
+      "deepRescanning": "Riscansione approfondita in corso…"
     },
     "changeCover": "Cambia copertina",
     "searchDeezer": "Cerca su Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} file",
     "doneTitle": "Scansione completata",
     "doneSubtitle": "{{added}} aggiunti · {{updated}} aggiornati · {{skipped}} saltati",
-    "scanningIn": "Scansione di {{dir}}"
+    "scanningIn": "Scansione di {{dir}}",
+    "doneErrors_one": "{{count}} file non riuscito",
+    "doneErrors_other": "{{count}} file non riusciti"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/ja.json b/src/i18n/locales/ja.json
index e70a272c..5bea50e6 100644
--- a/src/i18n/locales/ja.json
+++ b/src/i18n/locales/ja.json
@@ -389,7 +389,9 @@
       "edit": "ライブラリを変更する",
       "delete": "ライブラリを削除する",
       "deleteConfirm": "もう一度クリックして確認してください",
-      "importing": "インポート中…"
+      "importing": "インポート中…",
+      "deepRescan": "詳細再スキャン（全ファイルを読み直すため低速）",
+      "deepRescanning": "詳細再スキャン中…"
     },
     "changeCover": "ジャケットを変更する",
     "searchDeezer": "Deezerの検索",
@@ -1966,7 +1968,9 @@
     "runningSubtitle": "{{current}} / {{total}} ファイル",
     "doneTitle": "スキャン完了",
     "doneSubtitle": "{{added}} 追加 · {{updated}} 更新 · {{skipped}} スキップ",
-    "scanningIn": "{{dir}} をスキャン中"
+    "scanningIn": "{{dir}} をスキャン中",
+    "doneErrors_one": "{{count}} 件のファイルが失敗",
+    "doneErrors_other": "{{count}} 件のファイルが失敗"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/ko.json b/src/i18n/locales/ko.json
index fb65371b..d2d11829 100644
--- a/src/i18n/locales/ko.json
+++ b/src/i18n/locales/ko.json
@@ -389,7 +389,9 @@
       "edit": "라이브러리 수정",
       "delete": "라이브러리 삭제",
       "deleteConfirm": "확인을 위해 다시 클릭하세요",
-      "importing": "가져오는 중…"
+      "importing": "가져오는 중…",
+      "deepRescan": "정밀 재검색 (모든 파일을 다시 읽으므로 느림)",
+      "deepRescanning": "정밀 재검색 중…"
     },
     "changeCover": "앨범 아트 변경",
     "searchDeezer": "Deezer 검색",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}}개 파일",
     "doneTitle": "스캔 완료",
     "doneSubtitle": "{{added}}개 추가 · {{updated}}개 업데이트 · {{skipped}}개 건너뜀",
-    "scanningIn": "{{dir}} 스캔 중"
+    "scanningIn": "{{dir}} 스캔 중",
+    "doneErrors_one": "{{count}}개 파일 실패",
+    "doneErrors_other": "{{count}}개 파일 실패"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/nl.json b/src/i18n/locales/nl.json
index 8b9fd3e7..07686221 100644
--- a/src/i18n/locales/nl.json
+++ b/src/i18n/locales/nl.json
@@ -389,7 +389,9 @@
       "edit": "Bibliotheek bewerken",
       "delete": "Bibliotheek verwijderen",
       "deleteConfirm": "Klik nogmaals om te bevestigen",
-      "importing": "Importeren…"
+      "importing": "Importeren…",
+      "deepRescan": "Diepe herscan (leest elk bestand opnieuw, trager)",
+      "deepRescanning": "Diepe herscan bezig…"
     },
     "changeCover": "Albumhoes wijzigen",
     "searchDeezer": "Zoeken op Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} bestanden",
     "doneTitle": "Scan voltooid",
     "doneSubtitle": "{{added}} toegevoegd · {{updated}} bijgewerkt · {{skipped}} overgeslagen",
-    "scanningIn": "Bezig met {{dir}}"
+    "scanningIn": "Bezig met {{dir}}",
+    "doneErrors_one": "{{count}} bestand mislukt",
+    "doneErrors_other": "{{count}} bestanden mislukt"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/pt-BR.json b/src/i18n/locales/pt-BR.json
index 25b7afbd..5455dd22 100644
--- a/src/i18n/locales/pt-BR.json
+++ b/src/i18n/locales/pt-BR.json
@@ -389,7 +389,9 @@
       "edit": "Editar a biblioteca",
       "delete": "Excluir a biblioteca",
       "deleteConfirm": "Clique novamente para confirmar",
-      "importing": "Importando…"
+      "importing": "Importando…",
+      "deepRescan": "Reescaneamento profundo (relê todos os arquivos, mais lento)",
+      "deepRescanning": "Reescaneamento profundo em andamento…"
     },
     "changeCover": "Trocar a capa",
     "searchDeezer": "Pesquisar no Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} arquivos",
     "doneTitle": "Escaneamento concluído",
     "doneSubtitle": "{{added}} adicionados · {{updated}} atualizados · {{skipped}} ignorados",
-    "scanningIn": "Analisando {{dir}}"
+    "scanningIn": "Analisando {{dir}}",
+    "doneErrors_one": "{{count}} arquivo falhou",
+    "doneErrors_other": "{{count}} arquivos falharam"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/pt.json b/src/i18n/locales/pt.json
index 01a27238..7a07b21e 100644
--- a/src/i18n/locales/pt.json
+++ b/src/i18n/locales/pt.json
@@ -389,7 +389,9 @@
       "edit": "Editar a biblioteca",
       "delete": "Eliminar a biblioteca",
       "deleteConfirm": "Clica novamente para confirmar",
-      "importing": "A importar…"
+      "importing": "A importar…",
+      "deepRescan": "Reanálise profunda (relê todos os ficheiros, mais lenta)",
+      "deepRescanning": "Reanálise profunda em curso…"
     },
     "changeCover": "Mudar a capa",
     "searchDeezer": "Pesquisar no Deezer",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} ficheiros",
     "doneTitle": "Análise concluída",
     "doneSubtitle": "{{added}} adicionados · {{updated}} atualizados · {{skipped}} ignorados",
-    "scanningIn": "A analisar {{dir}}"
+    "scanningIn": "A analisar {{dir}}",
+    "doneErrors_one": "{{count}} ficheiro falhou",
+    "doneErrors_other": "{{count}} ficheiros falharam"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/ru.json b/src/i18n/locales/ru.json
index dbf9ee08..eda970a1 100644
--- a/src/i18n/locales/ru.json
+++ b/src/i18n/locales/ru.json
@@ -415,7 +415,9 @@
       "edit": "Изменить библиотеку",
       "delete": "Удалить библиотеку",
       "deleteConfirm": "Нажмите ещё раз для подтверждения",
-      "importing": "Импорт…"
+      "importing": "Импорт…",
+      "deepRescan": "Глубокое сканирование (перечитывает все файлы, медленнее)",
+      "deepRescanning": "Идёт глубокое сканирование…"
     },
     "changeCover": "Сменить обложку",
     "searchDeezer": "Поиск в Deezer",
@@ -2072,7 +2074,11 @@
     "runningSubtitle": "{{current}} / {{total}} файлов",
     "doneTitle": "Сканирование завершено",
     "doneSubtitle": "Добавлено: {{added}} · Обновлено: {{updated}} · Пропущено: {{skipped}}",
-    "scanningIn": "Сканирование {{dir}}"
+    "scanningIn": "Сканирование {{dir}}",
+    "doneErrors_one": "{{count}} файл не удалось обработать",
+    "doneErrors_few": "{{count}} файла не удалось обработать",
+    "doneErrors_many": "{{count}} файлов не удалось обработать",
+    "doneErrors_other": "{{count}} файлов не удалось обработать"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/tr.json b/src/i18n/locales/tr.json
index a838aa34..416e5bdd 100644
--- a/src/i18n/locales/tr.json
+++ b/src/i18n/locales/tr.json
@@ -389,7 +389,9 @@
       "edit": "Kütüphaneyi düzenle",
       "delete": "Kütüphaneyi sil",
       "deleteConfirm": "Onaylamak için tekrar tıkla",
-      "importing": "İçe aktarılıyor…"
+      "importing": "İçe aktarılıyor…",
+      "deepRescan": "Derin tarama (her dosyayı yeniden okur, daha yavaş)",
+      "deepRescanning": "Derin tarama sürüyor…"
     },
     "changeCover": "Kapağı değiştir",
     "searchDeezer": "Deezer'da ara",
@@ -1980,7 +1982,9 @@
     "runningSubtitle": "{{current}} / {{total}} dosya",
     "doneTitle": "Tarama tamamlandı",
     "doneSubtitle": "{{added}} eklendi · {{updated}} güncellendi · {{skipped}} atlandı",
-    "scanningIn": "Taranıyor: {{dir}}"
+    "scanningIn": "Taranıyor: {{dir}}",
+    "doneErrors_one": "{{count}} dosya başarısız",
+    "doneErrors_other": "{{count}} dosya başarısız"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/zh-CN.json b/src/i18n/locales/zh-CN.json
index d306abca..d8a5a9d5 100644
--- a/src/i18n/locales/zh-CN.json
+++ b/src/i18n/locales/zh-CN.json
@@ -389,7 +389,9 @@
       "edit": "编辑音乐库",
       "delete": "删除音乐库",
       "deleteConfirm": "再次点击以确认",
-      "importing": "正在导入…"
+      "importing": "正在导入…",
+      "deepRescan": "深度重新扫描（重新读取每个文件，较慢）",
+      "deepRescanning": "正在深度重新扫描…"
     },
     "changeCover": "更换封面",
     "searchDeezer": "搜索 Deezer",
@@ -1966,7 +1968,9 @@
     "runningSubtitle": "{{current}} / {{total}} 个文件",
     "doneTitle": "扫描完成",
     "doneSubtitle": "已添加 {{added}} · 已更新 {{updated}} · 已跳过 {{skipped}}",
-    "scanningIn": "正在扫描 {{dir}}"
+    "scanningIn": "正在扫描 {{dir}}",
+    "doneErrors_one": "{{count}} 个文件失败",
+    "doneErrors_other": "{{count}} 个文件失败"
   },
   "system": {
     "tray": {
diff --git a/src/i18n/locales/zh-TW.json b/src/i18n/locales/zh-TW.json
index c36a0a03..084a7d76 100644
--- a/src/i18n/locales/zh-TW.json
+++ b/src/i18n/locales/zh-TW.json
@@ -389,7 +389,9 @@
       "edit": "編輯音樂庫",
       "delete": "刪除音樂庫",
       "deleteConfirm": "請再次點擊以確認",
-      "importing": "正在匯入…"
+      "importing": "正在匯入…",
+      "deepRescan": "深度重新掃描（重新讀取每個檔案，較慢）",
+      "deepRescanning": "正在深度重新掃描…"
     },
     "changeCover": "更換封面",
     "searchDeezer": "搜尋Deezer",
@@ -1966,7 +1968,9 @@
     "runningSubtitle": "{{current}} / {{total}} 個檔案",
     "doneTitle": "掃描完成",
     "doneSubtitle": "已新增 {{added}} · 已更新 {{updated}} · 已略過 {{skipped}}",
-    "scanningIn": "正在掃描 {{dir}}"
+    "scanningIn": "正在掃描 {{dir}}",
+    "doneErrors_one": "{{count}} 個檔案失敗",
+    "doneErrors_other": "{{count}} 個檔案失敗"
   },
   "system": {
     "tray": {
diff --git a/src/lib/tauri/library.ts b/src/lib/tauri/library.ts
index 792d61c8..0d75e11a 100644
--- a/src/lib/tauri/library.ts
+++ b/src/lib/tauri/library.ts
@@ -81,8 +81,19 @@ export function deleteLibrary(libraryId: number): Promise<void> {
   return invoke<void>("delete_library", { libraryId });
 }
 
-export function rescanLibrary(libraryId: number): Promise<RescanSummary> {
-  return invoke<RescanSummary>("rescan_library", { libraryId });
+/**
+ * Rescan every folder of a library.
+ *
+ * `deep` bypasses the `(mtime, size)` fast path so every file is
+ * re-hashed and re-read. Needed when an external tagger rewrote tags
+ * while preserving mtime — Mp3tag does that by default — which the
+ * normal pass cannot see (issue #457). Slower, so it stays opt-in.
+ */
+export function rescanLibrary(
+  libraryId: number,
+  deep = false,
+): Promise<RescanSummary> {
+  return invoke<RescanSummary>("rescan_library", { libraryId, deep });
 }
 
 export function addFolderToLibrary(