diff --git a/components/settings/keyword-settings.tsx b/components/settings/keyword-settings.tsx
index d55317caa..ed2b35d56 100644
--- a/components/settings/keyword-settings.tsx
+++ b/components/settings/keyword-settings.tsx
@@ -12,6 +12,7 @@ import {
 } from "@/stores/settings-store";
 import { useAuthStore } from "@/stores/auth-store";
 import { useEmailStore } from "@/stores/email-store";
+import { useFilterStore } from "@/stores/filter-store";
 import { SettingsSection, SettingItem, ToggleSwitch, Select } from "./settings-section";
 import { Plus, Pencil, Trash2, GripVertical, Check, X, Loader2, Search } from "lucide-react";
 import { cn } from "@/lib/utils";
@@ -522,6 +523,7 @@ export function KeywordSettings() {
     useSettingsStore();
   const { client } = useAuthStore();
   const { fetchTagCounts } = useEmailStore();
+  const renameKeywordInFilters = useFilterStore((state) => state.renameKeywordInFilters);
   const [editingId, setEditingId] = useState<string | null>(null);
   const [isAdding, setIsAdding] = useState(false);
   const [isMigrating, setIsMigrating] = useState(false);
@@ -571,9 +573,9 @@ export function KeywordSettings() {
 
     if (idChanged && client) {
       setIsMigrating(true);
+      const oldJmapKeyword = `$label:${oldId}`;
+      const newJmapKeyword = `$label:${keyword.id}`;
       try {
-        const oldJmapKeyword = `$label:${oldId}`;
-        const newJmapKeyword = `$label:${keyword.id}`;
         await client.migrateKeyword(oldJmapKeyword, newJmapKeyword);
         renameKeyword(oldId, keyword);
         fetchTagCounts(client);
@@ -584,6 +586,41 @@ export function KeywordSettings() {
         setIsMigrating(false);
         return;
       }
+
+      // The messages now carry the new keyword, so the definition is right
+      // whatever happens next. Filter rules name the same id and would go on
+      // tagging new mail under the old one, so follow the rename into them -
+      // and say so when a rule is left behind, since only the user can fix a
+      // hand-edited script.
+      let rewroteFilters = false;
+      try {
+        const outcome = await renameKeywordInFilters(client, oldId, keyword.id);
+        rewroteFilters = outcome.changed > 0;
+        if (outcome.unhandled > 0) {
+          const toastModule = await import('sonner');
+          toastModule.toast.warning(t("filters_migration_error"));
+        }
+      } catch (error) {
+        console.error("Failed to migrate keyword in filters:", error);
+        const toastModule = await import('sonner');
+        toastModule.toast.warning(t("filters_migration_error"));
+      }
+
+      if (rewroteFilters) {
+        // Mail delivered between the migration above and the rewrite was still
+        // tagged by the old rule, and the migration has already passed it by.
+        // Sweep once more now that no rule can write the old keyword. A failure
+        // here is about the messages, not the filters, so it says so.
+        try {
+          await client.migrateKeyword(oldJmapKeyword, newJmapKeyword);
+          fetchTagCounts(client);
+        } catch (error) {
+          console.error("Failed to sweep up mail tagged during the rename:", error);
+          const toastModule = await import('sonner');
+          toastModule.toast.error(t("migration_error"));
+        }
+      }
+
       setIsMigrating(false);
     } else {
       updateKeyword(oldId, { label: keyword.label, color: keyword.color });
diff --git a/lib/sieve/__tests__/keyword-rename.test.ts b/lib/sieve/__tests__/keyword-rename.test.ts
new file mode 100644
index 000000000..eb89bd348
--- /dev/null
+++ b/lib/sieve/__tests__/keyword-rename.test.ts
@@ -0,0 +1,156 @@
+import { describe, it, expect } from 'vitest';
+import { countKeywordUses, renameKeywordInRules } from '../keyword-rename';
+import type { FilterRule } from '@/lib/jmap/sieve-types';
+
+const makeRule = (overrides: Partial<FilterRule> = {}): FilterRule => ({
+  id: 'rule-1',
+  name: 'ISO',
+  enabled: true,
+  matchType: 'all',
+  conditions: [{ field: 'from', comparator: 'contains', value: 'iso.org' }],
+  actions: [{ type: 'add_label', value: 'red' }],
+  stopProcessing: false,
+  ...overrides,
+});
+
+describe('renameKeywordInRules', () => {
+  it('rewrites an add_label action that names the old tag', () => {
+    const { rules, changed } = renameKeywordInRules([makeRule()], 'red', 'iso');
+    expect(changed).toBe(1);
+    expect(rules[0].actions[0]).toEqual({ type: 'add_label', value: 'iso' });
+  });
+
+  it('leaves actions naming a different tag alone', () => {
+    const rules = [makeRule({ actions: [{ type: 'add_label', value: 'blue' }] })];
+    const result = renameKeywordInRules(rules, 'red', 'iso');
+    expect(result.changed).toBe(0);
+    expect(result.rules[0].actions[0].value).toBe('blue');
+  });
+
+  it('leaves actions of other types alone even when the value collides', () => {
+    const rules = [makeRule({ actions: [{ type: 'move', value: 'red' }] })];
+    const result = renameKeywordInRules(rules, 'red', 'iso');
+    expect(result.changed).toBe(0);
+    expect(result.rules[0].actions[0].value).toBe('red');
+  });
+
+  it('counts every action it rewrites, across rules', () => {
+    const rules = [
+      makeRule({ id: 'r1' }),
+      makeRule({ id: 'r2', actions: [{ type: 'star' }, { type: 'add_label', value: 'red' }] }),
+    ];
+    expect(renameKeywordInRules(rules, 'red', 'iso').changed).toBe(2);
+  });
+
+  it('rewrites a disabled rule too, so enabling it later still tags correctly', () => {
+    const { changed, rules } = renameKeywordInRules([makeRule({ enabled: false })], 'red', 'iso');
+    expect(changed).toBe(1);
+    expect(rules[0].actions[0].value).toBe('iso');
+  });
+
+  it('does nothing when the id is unchanged', () => {
+    const rules = [makeRule()];
+    const result = renameKeywordInRules(rules, 'red', 'red');
+    expect(result).toEqual({ rules, changed: 0 });
+    expect(result.rules).toBe(rules);
+  });
+
+  it('does not mutate the rules it was given', () => {
+    const rules = [makeRule()];
+    renameKeywordInRules(rules, 'red', 'iso');
+    expect(rules[0].actions[0].value).toBe('red');
+  });
+
+  it('rewrites the raw block of an external rule, which is emitted verbatim', () => {
+    const rules = [
+      makeRule({
+        origin: 'external',
+        rawBlock: '# hand written\nif header :contains "From" "iso.org" {\n    addflag "$label:red";\n}',
+      }),
+    ];
+    const { rules: renamed, changed } = renameKeywordInRules(rules, 'red', 'iso');
+    expect(changed).toBe(1);
+    expect(renamed[0].rawBlock).toContain('addflag "$label:iso";');
+    expect(renamed[0].rawBlock).not.toContain('$label:red');
+  });
+
+  it('rewrites only the addflag operand of a raw block, not a matching test string', () => {
+    const rules = [
+      makeRule({
+        origin: 'external',
+        rawBlock: 'if header :contains "X-Tag" "$label:red" {\n    addflag "$label:red";\n}',
+      }),
+    ];
+    const { rules: renamed, changed } = renameKeywordInRules(rules, 'red', 'iso');
+    expect(changed).toBe(1);
+    expect(renamed[0].rawBlock).toContain('addflag "$label:iso";');
+    expect(renamed[0].rawBlock).toContain('header :contains "X-Tag" "$label:red"');
+  });
+
+  it('leaves an opaque rule, which has no parsed actions, untouched', () => {
+    const rules = [
+      makeRule({
+        origin: 'opaque',
+        actions: [],
+        conditions: [],
+        rawBlock: '# unparseable\nif anyof (true) {\n    addflag "$label:red";\n}',
+      }),
+    ];
+    const result = renameKeywordInRules(rules, 'red', 'iso');
+    expect(result.changed).toBe(0);
+    expect(result.rules[0].rawBlock).toContain('$label:red');
+  });
+
+  it('does not touch a raw block whose keyword only shares a prefix with the old id', () => {
+    const rules = [
+      makeRule({
+        origin: 'external',
+        actions: [{ type: 'add_label', value: 'red-alert' }],
+        rawBlock: 'if true {\n    addflag "$label:red-alert";\n}',
+      }),
+    ];
+    const { rules: renamed, changed } = renameKeywordInRules(rules, 'red', 'iso');
+    expect(changed).toBe(0);
+    expect(renamed[0].rawBlock).toContain('$label:red-alert');
+  });
+
+  it('rewrites a nested id without treating its separator as a pattern', () => {
+    const rules = [
+      makeRule({
+        actions: [{ type: 'add_label', value: 'work/clients' }],
+        origin: 'external',
+        rawBlock: 'if true {\n    addflag "$label:work/clients";\n}',
+      }),
+    ];
+    const { rules: renamed, changed } = renameKeywordInRules(rules, 'work/clients', 'work/acme');
+    expect(changed).toBe(1);
+    expect(renamed[0].actions[0].value).toBe('work/acme');
+    expect(renamed[0].rawBlock).toContain('addflag "$label:work/acme";');
+  });
+});
+
+describe('countKeywordUses', () => {
+  it('counts the keyword as it is written in a script', () => {
+    const script = 'if true {\n    addflag "$label:red";\n}\nif false {\n    addflag "$label:red";\n}';
+    expect(countKeywordUses(script, 'red')).toBe(2);
+  });
+
+  it('does not count a keyword that merely starts with the id', () => {
+    expect(countKeywordUses('addflag "$label:red-alert";', 'red')).toBe(0);
+  });
+
+  it('returns zero for a script that never names the tag', () => {
+    expect(countKeywordUses('addflag "\\\\Seen";', 'red')).toBe(0);
+  });
+
+  it('counts the tag in a multi-flag argument, which is one Sieve string', () => {
+    // RFC 5232 section 3.2: the argument is a space-separated flag list, so the
+    // keyword is not always followed by the closing quote.
+    expect(countKeywordUses('addflag "$label:red \\\\Seen";', 'red')).toBe(1);
+    expect(countKeywordUses('addflag "\\\\Seen $label:red";', 'red')).toBe(1);
+  });
+
+  it('still does not count a longer tag that starts with the id', () => {
+    expect(countKeywordUses('addflag "$label:red-alert \\\\Seen";', 'red')).toBe(0);
+  });
+});
diff --git a/lib/sieve/keyword-rename.ts b/lib/sieve/keyword-rename.ts
new file mode 100644
index 000000000..834acc00a
--- /dev/null
+++ b/lib/sieve/keyword-rename.ts
@@ -0,0 +1,100 @@
+/**
+ * Following a renamed tag into the filters that name it.
+ *
+ * A tag is stored on messages as the keyword `$label:<id>`, and `id` is a slug
+ * of the display name - so renaming a tag changes its id, and every message
+ * carrying it has to be migrated (`IJMAPClient.migrateKeyword`). A Sieve rule
+ * with an `add_label` action names that same id, in the generated `addflag`
+ * line and in the metadata block the visual editor reads back. Migrating only
+ * the messages leaves the rule writing the old keyword: new mail keeps arriving
+ * under a tag no definition names any more, which reads as "the filter stopped
+ * working" while the rule is in fact running exactly as written.
+ *
+ * This module is the rewrite half. It is pure - the caller fetches the script,
+ * parses it, applies this, and writes the result back.
+ */
+import type { FilterAction, FilterRule } from '@/lib/jmap/sieve-types';
+import { KEYWORD_PREFIX } from '@/lib/thread-utils';
+
+/** The result of following a rename through a set of rules. */
+export interface KeywordRenameResult {
+  /** The rules, with every reference to the old id rewritten. */
+  rules: FilterRule[];
+  /** How many actions were rewritten. Zero means nothing referenced the tag. */
+  changed: number;
+}
+
+/** The keyword an `add_label` action writes, as it appears in a script. */
+function quotedKeyword(id: string): string {
+  return `"${KEYWORD_PREFIX}${id}"`;
+}
+
+function escapeRegExp(value: string): string {
+  return value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+}
+
+/**
+ * How many times `script` writes the keyword of the tag `id`.
+ *
+ * Whole-token only: `$label:red-alert` is a different tag from `$label:red`
+ * and must not be counted, which a plain substring search would get wrong. The
+ * token ends at the closing quote or at a space, since the argument of an
+ * `addflag` is a space-separated flag list (RFC 5232 section 3.2) and the tag
+ * need not be the last flag in it.
+ *
+ * Used to tell whether a script this module cannot rewrite - a hand-edited one,
+ * kept verbatim - still refers to a tag that has since been renamed.
+ */
+export function countKeywordUses(script: string, id: string): number {
+  const pattern = new RegExp(`["\\s]${escapeRegExp(KEYWORD_PREFIX + id)}(?=["\\s])`, 'g');
+  return script.match(pattern)?.length ?? 0;
+}
+
+/**
+ * `rules` with every `add_label` action naming `oldId` rewritten to `newId`.
+ *
+ * Disabled rules are rewritten too: leaving one behind would have it tag under
+ * the old id the moment it is switched back on. An external rule - one Bulwark
+ * did not write, re-emitted from its `rawBlock` verbatim - has that block
+ * rewritten as well, since its parsed actions never reach the generated script.
+ * Only the operand of an `addflag` is touched there: a test comparing some
+ * header against the same literal is the rule's own logic, and rewriting it
+ * would change what the rule matches rather than what it tags.
+ *
+ * What is left naming the old id afterwards - that test, or an opaque rule,
+ * which parses to no actions at all - is for the caller to count in the script
+ * it ends up writing, with `countKeywordUses`. The input is left untouched, and
+ * an id that did not actually change returns the very same array, so a caller
+ * can skip writing anything.
+ */
+export function renameKeywordInRules(
+  rules: FilterRule[],
+  oldId: string,
+  newId: string,
+): KeywordRenameResult {
+  if (!oldId || !newId || oldId === newId) return { rules, changed: 0 };
+
+  let changed = 0;
+  const rewritten = rules.map((rule) => {
+    let ruleChanged = 0;
+    const actions: FilterAction[] = rule.actions.map((action) => {
+      if (action.type !== 'add_label' || action.value !== oldId) return action;
+      ruleChanged++;
+      return { ...action, value: newId };
+    });
+    if (ruleChanged === 0) return rule;
+
+    changed += ruleChanged;
+    const next: FilterRule = { ...rule, actions };
+    if (next.rawBlock) next.rawBlock = renameInRawBlock(next.rawBlock, oldId, newId);
+    return next;
+  });
+
+  return changed === 0 ? { rules, changed: 0 } : { rules: rewritten, changed };
+}
+
+/** Retags the `addflag` lines of a block that is otherwise kept verbatim. */
+function renameInRawBlock(block: string, oldId: string, newId: string): string {
+  const pattern = new RegExp(`(addflag\\s+)${escapeRegExp(quotedKeyword(oldId))}`, 'g');
+  return block.replace(pattern, `$1${quotedKeyword(newId)}`);
+}
diff --git a/locales/ar/common.json b/locales/ar/common.json
index b39180bb8..4cc80837a 100644
--- a/locales/ar/common.json
+++ b/locales/ar/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "إلغاء",
       "migrating": "جارٍ تحديث الوسم على الرسائل الحالية…",
       "migration_error": "فشل تحديث الوسم على الرسائل الحالية",
+      "filters_migration_error": "لا تزال بعض قواعد التصفية تستخدم الوسم القديم — حدّثها يدويًا",
       "nesting": {
         "label": "وسوم متداخلة",
         "description": "ضع الوسوم داخل وسوم أخرى واعرضها كشجرة في الشريط الجانبي."
diff --git a/locales/ca/common.json b/locales/ca/common.json
index 22f503834..8cb96b534 100644
--- a/locales/ca/common.json
+++ b/locales/ca/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "Cancel·la",
       "migrating": "Actualitzant l'etiqueta als correus existents…",
       "migration_error": "No s'ha pogut actualitzar l'etiqueta als correus existents",
+      "filters_migration_error": "Algunes regles de filtre encara fan servir l'etiqueta antiga: actualitza-les manualment",
       "nesting": {
         "label": "Etiquetes imbricades",
         "description": "Imbrica etiquetes sota altres etiquetes i mostra-les com un arbre a la barra lateral."
diff --git a/locales/cs/common.json b/locales/cs/common.json
index 2570b45f2..6c469184d 100644
--- a/locales/cs/common.json
+++ b/locales/cs/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Zrušit",
       "migrating": "Aktualizace štítku v existujících e-mailech…",
       "migration_error": "Nepodařilo se aktualizovat štítek v existujících e-mailech",
+      "filters_migration_error": "Některá pravidla filtrů stále používají starý štítek – upravte je ručně",
       "nesting": {
         "label": "Vnořené štítky",
         "description": "Vnořujte štítky pod jiné štítky a zobrazujte je v postranním panelu jako strom."
diff --git a/locales/da/common.json b/locales/da/common.json
index 3cb27e398..8c8e5911f 100644
--- a/locales/da/common.json
+++ b/locales/da/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "Annuller",
       "migrating": "Opdaterer tag på eksisterende e-mails…",
       "migration_error": "Kunne ikke opdatere tag på eksisterende e-mails",
+      "filters_migration_error": "Nogle filterregler bruger stadig det gamle tag – opdatér dem manuelt",
       "nesting": {
         "label": "Indlejrede tags",
         "description": "Indlejr tags under andre tags og vis dem som et træ i sidepanelet."
diff --git a/locales/de/common.json b/locales/de/common.json
index d4d7045a6..e9edc7ce0 100644
--- a/locales/de/common.json
+++ b/locales/de/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Abbrechen",
       "migrating": "Label auf vorhandenen E-Mails aktualisieren…",
       "migration_error": "Label auf vorhandenen E-Mails konnte nicht aktualisiert werden",
+      "filters_migration_error": "Einige Filterregeln verwenden noch das alte Tag – aktualisieren Sie sie manuell",
       "nesting": {
         "label": "Verschachtelte Labels",
         "description": "Labels unter anderen Labels verschachteln und als Baum in der Seitenleiste anzeigen."
diff --git a/locales/en/common.json b/locales/en/common.json
index 9280dc65f..af82d5c12 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -1039,6 +1039,7 @@
       "cancel": "Cancel",
       "migrating": "Updating tag on existing emails…",
       "migration_error": "Failed to update tag on existing emails",
+      "filters_migration_error": "Some filter rules still use the old tag — update them manually",
       "nesting": {
         "label": "Nested Tags",
         "description": "Nest tags underneath other tags and show them as a tree in the sidebar."
diff --git a/locales/es/common.json b/locales/es/common.json
index 25e20438e..c3a7bd147 100644
--- a/locales/es/common.json
+++ b/locales/es/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Cancelar",
       "migrating": "Actualizando etiqueta en correos existentes…",
       "migration_error": "Error al actualizar la etiqueta en correos existentes",
+      "filters_migration_error": "Algunas reglas de filtro siguen usando la etiqueta anterior: actualízalas manualmente",
       "nesting": {
         "label": "Etiquetas anidadas",
         "description": "Anida etiquetas debajo de otras etiquetas y muéstralas como un árbol en la barra lateral."
diff --git a/locales/fa/common.json b/locales/fa/common.json
index 629d514fc..f86e70041 100644
--- a/locales/fa/common.json
+++ b/locales/fa/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "انصراف",
       "migrating": "در حال به‌روزرسانی برچسب روی ایمیل‌های موجود…",
       "migration_error": "به‌روزرسانی برچسب ناموفق بود",
+      "filters_migration_error": "برخی قوانین فیلتر هنوز از برچسب قدیمی استفاده می‌کنند — آن‌ها را دستی به‌روزرسانی کنید",
       "nesting": {
         "label": "برچسب‌های تودرتو",
         "description": "برچسب‌ها را زیر برچسب‌های دیگر قرار دهید و آن‌ها را به‌صورت درختی در نوار کناری نمایش دهید."
diff --git a/locales/fr/common.json b/locales/fr/common.json
index 366374a3e..ece99103e 100644
--- a/locales/fr/common.json
+++ b/locales/fr/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Annuler",
       "migrating": "Mise à jour de l'étiquette sur les e-mails existants…",
       "migration_error": "Impossible de mettre à jour l'étiquette sur les e-mails existants",
+      "filters_migration_error": "Certaines règles de filtrage utilisent encore l'ancienne étiquette — mettez-les à jour manuellement",
       "nesting": {
         "label": "Étiquettes imbriquées",
         "description": "Imbriquez des étiquettes sous d'autres étiquettes et affichez-les sous forme d'arborescence dans la barre latérale."
diff --git a/locales/he/common.json b/locales/he/common.json
index bc6c7f5d1..4d87be04b 100644
--- a/locales/he/common.json
+++ b/locales/he/common.json
@@ -998,6 +998,7 @@
       "cancel": "לְבַטֵל",
       "migrating": "מעדכן מילת מפתח באימיילים קיימים...",
       "migration_error": "נכשל עדכון מילת המפתח בהודעות דוא\"ל קיימות",
+      "filters_migration_error": "חלק מכללי הסינון עדיין משתמשים בתגית הישנה — עדכנו אותם ידנית",
       "nesting": {
         "label": "תגים מקוננים",
         "description": "קנן תגים תחת תגים אחרים והצג אותם כעץ בסרגל הצד."
diff --git a/locales/hu/common.json b/locales/hu/common.json
index c1d7170f8..b2838d7c2 100644
--- a/locales/hu/common.json
+++ b/locales/hu/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "Mégse",
       "migrating": "Címke frissítése a meglévő e-maileken...",
       "migration_error": "Nem sikerült frissíteni a címkét a meglévő e-maileken",
+      "filters_migration_error": "Néhány szűrőszabály még a régi címkét használja – frissítse őket kézzel",
       "nesting": {
         "label": "Beágyazott címkék",
         "description": "Ágyazzon címkéket más címkék alá, és jelenítse meg őket fastruktúraként az oldalsávon."
diff --git a/locales/it/common.json b/locales/it/common.json
index 45a2bc615..8949e984b 100644
--- a/locales/it/common.json
+++ b/locales/it/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Annulla",
       "migrating": "Aggiornamento dell'etichetta nelle e-mail esistenti…",
       "migration_error": "Impossibile aggiornare l'etichetta nelle e-mail esistenti",
+      "filters_migration_error": "Alcune regole dei filtri usano ancora il vecchio tag: aggiornale manualmente",
       "nesting": {
         "label": "Etichette nidificate",
         "description": "Nidifica le etichette sotto altre etichette e mostrale come un albero nella barra laterale."
diff --git a/locales/ja/common.json b/locales/ja/common.json
index d4b7d4df4..2a09694ab 100644
--- a/locales/ja/common.json
+++ b/locales/ja/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "キャンセル",
       "migrating": "既存のメールのラベルを更新中…",
       "migration_error": "既存のメールのラベルの更新に失敗しました",
+      "filters_migration_error": "一部のフィルタールールが古いタグを使用しています。手動で更新してください",
       "nesting": {
         "label": "ネストされたラベル",
         "description": "ラベルを他のラベルの下にネストし、サイドバーにツリーとして表示します。"
diff --git a/locales/ko/common.json b/locales/ko/common.json
index 56ed12e9d..cf2136d3b 100644
--- a/locales/ko/common.json
+++ b/locales/ko/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "취소",
       "migrating": "기존 이메일의 태그 업데이트 중…",
       "migration_error": "기존 이메일의 태그 업데이트에 실패했습니다",
+      "filters_migration_error": "일부 필터 규칙이 여전히 이전 태그를 사용합니다. 수동으로 업데이트하세요",
       "nesting": {
         "label": "중첩 태그",
         "description": "태그를 다른 태그 아래에 중첩하고 사이드바에 트리로 표시합니다."
diff --git a/locales/lv/common.json b/locales/lv/common.json
index 0c4f15193..404d6b8e5 100644
--- a/locales/lv/common.json
+++ b/locales/lv/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Atcelt",
       "migrating": "Taga atjaunināšana esošajos e-pastos…",
       "migration_error": "Neizdevās atjaunināt tagu esošajos e-pastos",
+      "filters_migration_error": "Dažas filtru kārtulas joprojām izmanto veco tagu — atjauniniet tās manuāli",
       "nesting": {
         "label": "Ligzdoti tagi",
         "description": "Ligzdojiet tagus zem citiem tagiem un rādiet tos sānjoslā kā koku."
diff --git a/locales/mn/common.json b/locales/mn/common.json
index 59424b3d0..ebd47de5a 100644
--- a/locales/mn/common.json
+++ b/locales/mn/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "Цуцлах",
       "migrating": "Одоо байгаа имэйлүүд дээрх шошгыг шинэчилж байна...",
       "migration_error": "Одоо байгаа имэйлийн шошгыг шинэчилж чадсангүй",
+      "filters_migration_error": "Зарим шүүлтүүрийн дүрэм хуучин шошгыг ашигласаар байна — гараар шинэчилнэ үү",
       "nesting": {
         "label": "Оруулсан шошго",
         "description": "Тагуудыг бусад шошгоны доор байрлуулж, хажуугийн самбарт мод хэлбэрээр харуул."
diff --git a/locales/nl/common.json b/locales/nl/common.json
index c8e460521..ee072b7a2 100644
--- a/locales/nl/common.json
+++ b/locales/nl/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Annuleren",
       "migrating": "Label bijwerken op bestaande e-mails…",
       "migration_error": "Label bijwerken op bestaande e-mails mislukt",
+      "filters_migration_error": "Sommige filterregels gebruiken nog het oude label — werk ze handmatig bij",
       "nesting": {
         "label": "Geneste labels",
         "description": "Nest labels onder andere labels en toon ze als een boomstructuur in de zijbalk."
diff --git a/locales/pl/common.json b/locales/pl/common.json
index f4d1fa706..7425ed449 100644
--- a/locales/pl/common.json
+++ b/locales/pl/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Anuluj",
       "migrating": "Aktualizowanie etykiety w istniejących e-mailach…",
       "migration_error": "Nie udało się zaktualizować etykiety w istniejących e-mailach",
+      "filters_migration_error": "Niektóre reguły filtrów nadal używają starego tagu — zaktualizuj je ręcznie",
       "nesting": {
         "label": "Zagnieżdżone etykiety",
         "description": "Zagnieżdżaj etykiety pod innymi etykietami i wyświetlaj je w panelu bocznym jako drzewo."
diff --git a/locales/pt/common.json b/locales/pt/common.json
index d234128a5..8d8d8614e 100644
--- a/locales/pt/common.json
+++ b/locales/pt/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Cancelar",
       "migrating": "A atualizar etiqueta nos e-mails existentes…",
       "migration_error": "Falha ao atualizar etiqueta nos e-mails existentes",
+      "filters_migration_error": "Algumas regras de filtro ainda usam a etiqueta antiga — atualize-as manualmente",
       "nesting": {
         "label": "Etiquetas aninhadas",
         "description": "Aninhe etiquetas sob outras etiquetas e mostre-as como uma árvore na barra lateral."
diff --git a/locales/ro/common.json b/locales/ro/common.json
index 1a0d06a7d..31b87bbd0 100644
--- a/locales/ro/common.json
+++ b/locales/ro/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "Anulează",
       "migrating": "Actualizarea etichetei pentru e-mailurile existente…",
       "migration_error": "Nu s-a putut actualiza eticheta pentru e-mailurile existente",
+      "filters_migration_error": "Unele reguli de filtrare folosesc încă eticheta veche — actualizează-le manual",
       "nesting": {
         "label": "Etichete imbricate",
         "description": "Imbricați etichete sub alte etichete și afișați-le ca un arbore în bara laterală."
diff --git a/locales/ru/common.json b/locales/ru/common.json
index 4725a400c..498b3f1f2 100644
--- a/locales/ru/common.json
+++ b/locales/ru/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Отмена",
       "migrating": "Обновление тега в существующих письмах…",
       "migration_error": "Не удалось обновить тег в существующих письмах",
+      "filters_migration_error": "Некоторые правила фильтров всё ещё используют старый тег — обновите их вручную",
       "nesting": {
         "label": "Вложенные теги",
         "description": "Вкладывайте теги в другие теги и показывайте их в боковой панели в виде дерева."
diff --git a/locales/sk/common.json b/locales/sk/common.json
index 6cded9d01..d0a2ffd77 100644
--- a/locales/sk/common.json
+++ b/locales/sk/common.json
@@ -1036,6 +1036,7 @@
       "cancel": "Zrušiť",
       "migrating": "Aktualizácia štítku v existujúcich e-mailoch…",
       "migration_error": "Nepodarilo sa aktualizovať štítok v existujúcich e-mailoch",
+      "filters_migration_error": "Niektoré pravidlá filtrov stále používajú starý štítok – upravte ich ručne",
       "nesting": {
         "label": "Vnorené štítky",
         "description": "Vnorujte štítky pod iné štítky a zobrazujte ich v bočnom paneli ako strom."
diff --git a/locales/tr/common.json b/locales/tr/common.json
index 65d2da05a..3f9ab7354 100644
--- a/locales/tr/common.json
+++ b/locales/tr/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "İptal",
       "migrating": "Mevcut e-postalardaki etiket güncelleniyor…",
       "migration_error": "Mevcut e-postalardaki etiket güncellenemedi",
+      "filters_migration_error": "Bazı filtre kuralları hâlâ eski etiketi kullanıyor — bunları elle güncelleyin",
       "nesting": {
         "label": "İç içe etiketler",
         "description": "Etiketleri başka etiketlerin altına yerleştirin ve kenar çubuğunda ağaç olarak gösterin."
diff --git a/locales/uk/common.json b/locales/uk/common.json
index f21e1ebb3..61b311614 100644
--- a/locales/uk/common.json
+++ b/locales/uk/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "Скасувати",
       "migrating": "Оновлення ключового слова в наявних електронних листах…",
       "migration_error": "Не вдалося оновити ключове слово в існуючих електронних листах",
+      "filters_migration_error": "Деякі правила фільтрів досі використовують старий тег — оновіть їх вручну",
       "nesting": {
         "label": "Вкладені теги",
         "description": "Вкладайте теги в інші теги та показуйте їх на бічній панелі у вигляді дерева."
diff --git a/locales/zh/common.json b/locales/zh/common.json
index 7bd5deab1..2b92cd38c 100644
--- a/locales/zh/common.json
+++ b/locales/zh/common.json
@@ -1033,6 +1033,7 @@
       "cancel": "取消",
       "migrating": "正在更新现有邮件的标签…",
       "migration_error": "更新现有邮件的标签失败",
+      "filters_migration_error": "部分过滤规则仍在使用旧标签，请手动更新",
       "nesting": {
         "label": "嵌套标签",
         "description": "将标签嵌套在其他标签之下，并在侧边栏中以树形显示。"
diff --git a/stores/__tests__/filter-store-keyword-rename.test.ts b/stores/__tests__/filter-store-keyword-rename.test.ts
new file mode 100644
index 000000000..ff936c301
--- /dev/null
+++ b/stores/__tests__/filter-store-keyword-rename.test.ts
@@ -0,0 +1,202 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { useFilterStore } from '../filter-store';
+import { generateScript } from '@/lib/sieve/generator';
+import { filterHooks } from '@/lib/plugin-hooks';
+import type { FilterRule } from '@/lib/jmap/sieve-types';
+import type { IJMAPClient } from '@/lib/jmap/client-interface';
+
+const makeRule = (overrides: Partial<FilterRule> = {}): FilterRule => ({
+  id: 'rule-1',
+  name: 'ISO',
+  enabled: true,
+  matchType: 'all',
+  conditions: [{ field: 'from', comparator: 'contains', value: 'iso.org' }],
+  actions: [{ type: 'add_label', value: 'red' }],
+  stopProcessing: false,
+  ...overrides,
+});
+
+/** A client serving one active script, recording what gets written back. */
+function makeClient(content: string, scriptsOverride?: { id: string; name: string; blobId: string; isActive: boolean }[]) {
+  const updateSieveScript = vi.fn(
+    async (_scriptId: string, _content: string, _activate?: boolean, _accountId?: string) => {},
+  );
+  const client = {
+    supportsSieve: () => true,
+    getSieveAccountId: () => 'primary',
+    getSieveAccounts: () => [{ id: 'primary', name: 'Me', isPrimary: true }],
+    getSieveCapabilities: () => null,
+    getSieveScripts: async () => scriptsOverride ?? [
+      { id: 'vac', name: 'vacation', blobId: 'bv', isActive: false },
+      { id: 's1', name: 'filters', blobId: 'b1', isActive: true },
+    ],
+    getSieveScriptContent: async () => content,
+    updateSieveScript,
+  };
+  return { client: client as unknown as IJMAPClient, updateSieveScript };
+}
+
+describe('filter-store renameKeywordInFilters', () => {
+  beforeEach(() => {
+    useFilterStore.getState().clearState();
+  });
+
+  it('rewrites the tag in the active script and uploads it', async () => {
+    const { client, updateSieveScript } = makeClient(generateScript([makeRule()]));
+
+    const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(outcome).toEqual({ changed: 1, unhandled: 0 });
+    expect(updateSieveScript).toHaveBeenCalledTimes(1);
+    const [scriptId, uploaded, activate, accountId] = updateSieveScript.mock.calls[0];
+    expect(scriptId).toBe('s1');
+    expect(activate).toBe(true);
+    expect(accountId).toBe('primary');
+    expect(uploaded).toContain('addflag "$label:iso";');
+    expect(uploaded).not.toContain('$label:red');
+  });
+
+  it('rewrites the metadata block the visual editor reads back', async () => {
+    const { client, updateSieveScript } = makeClient(generateScript([makeRule()]));
+
+    await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    const uploaded = updateSieveScript.mock.calls[0][1];
+    const metadata = uploaded.match(/@metadata:begin\n([\s\S]*)\n@metadata:end/)?.[1];
+    expect(metadata).toBeDefined();
+    const parsed = JSON.parse(metadata as string) as { rules: FilterRule[] };
+    expect(parsed.rules[0].actions[0]).toEqual({ type: 'add_label', value: 'iso' });
+  });
+
+  it('writes nothing when no rule names the tag', async () => {
+    const script = generateScript([makeRule({ actions: [{ type: 'add_label', value: 'blue' }] })]);
+    const { client, updateSieveScript } = makeClient(script);
+
+    const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(outcome).toEqual({ changed: 0, unhandled: 0 });
+    expect(updateSieveScript).not.toHaveBeenCalled();
+  });
+
+  it('leaves a hand-edited script alone and reports what it could not rewrite', async () => {
+    const { client, updateSieveScript } = makeClient(
+      '/* @metadata:begin\n{corrupt\n@metadata:end */\naddflag "$label:red";',
+    );
+
+    const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(outcome).toEqual({ changed: 0, unhandled: 1 });
+    expect(updateSieveScript).not.toHaveBeenCalled();
+  });
+
+  it('keeps an open filter view in step when it shows the same account', async () => {
+    const { client } = makeClient(generateScript([makeRule()]));
+    await useFilterStore.getState().fetchFilters(client);
+    expect(useFilterStore.getState().rules[0].actions[0].value).toBe('red');
+
+    await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(useFilterStore.getState().rules[0].actions[0].value).toBe('iso');
+    expect(useFilterStore.getState().rawScript).toContain('$label:iso');
+  });
+
+  it('does not touch loaded state belonging to another account', async () => {
+    const { client } = makeClient(generateScript([makeRule()]));
+    useFilterStore.setState({ selectedAccountId: 'shared', rules: [makeRule({ id: 'other' })] });
+
+    await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(useFilterStore.getState().rules[0].id).toBe('other');
+    expect(useFilterStore.getState().rules[0].actions[0].value).toBe('red');
+  });
+
+  it('does nothing when the account has no script at all', async () => {
+    const client = {
+      supportsSieve: () => true,
+      getSieveAccountId: () => 'primary',
+      getSieveScripts: async () => [],
+    } as unknown as IJMAPClient;
+
+    const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(outcome).toEqual({ changed: 0, unhandled: 0 });
+  });
+
+  it('leaves an inactive script alone rather than activating it by writing to it', async () => {
+    const { client, updateSieveScript } = makeClient(generateScript([makeRule()]), [
+      { id: 's1', name: 'filters', blobId: 'b1', isActive: false },
+    ]);
+
+    const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(outcome).toEqual({ changed: 0, unhandled: 0 });
+    expect(updateSieveScript).not.toHaveBeenCalled();
+  });
+
+  it('does nothing on a server without Sieve', async () => {
+    const client = {
+      supportsSieve: () => false,
+      getSieveAccountId: () => 'primary',
+      getSieveScripts: async () => {
+        throw new Error('should not be called');
+      },
+    } as unknown as IJMAPClient;
+
+    await expect(
+      useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso'),
+    ).resolves.toEqual({ changed: 0, unhandled: 0 });
+  });
+
+  it('reports a reference it could not rewrite alongside the ones it did', async () => {
+    const script = `${generateScript([makeRule()])}\n# unmanaged\nif header :contains "X-Tag" "$label:red" {\n    keep;\n}\n`;
+    const { client, updateSieveScript } = makeClient(script);
+
+    const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+
+    expect(outcome.changed).toBe(1);
+    expect(outcome.unhandled).toBe(1);
+    expect(updateSieveScript).toHaveBeenCalledTimes(1);
+  });
+
+  it('counts what a plugin grafted back on as unhandled, since that is what gets written', async () => {
+    const { client } = makeClient(generateScript([makeRule()]));
+    const registration = filterHooks.onSieveScriptGenerate.register(
+      'test-plugin',
+      (script: string) => `# plugin section\nif true {\n    addflag "$label:red";\n}\n${script}`,
+    );
+
+    try {
+      const outcome = await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+      expect(outcome).toEqual({ changed: 1, unhandled: 1 });
+    } finally {
+      registration.dispose();
+    }
+  });
+
+  it('runs the uploaded script through the plugin generate hook', async () => {
+    const { client, updateSieveScript } = makeClient(generateScript([makeRule()]));
+    const registration = filterHooks.onSieveScriptGenerate.register(
+      'test-plugin',
+      (script: string) => `# plugin section\n${script}`,
+    );
+
+    try {
+      await useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso');
+    } finally {
+      registration.dispose();
+    }
+
+    expect(updateSieveScript.mock.calls[0][1]).toContain('# plugin section');
+  });
+
+  it('propagates a failed upload so the caller can warn', async () => {
+    const { client } = makeClient(generateScript([makeRule()]));
+    (client as unknown as { updateSieveScript: unknown }).updateSieveScript = vi.fn(async () => {
+      throw new Error('over quota');
+    });
+
+    await expect(
+      useFilterStore.getState().renameKeywordInFilters(client, 'red', 'iso'),
+    ).rejects.toThrow('over quota');
+  });
+});
diff --git a/stores/filter-store.ts b/stores/filter-store.ts
index 0964aefc1..7142a4b5c 100644
--- a/stores/filter-store.ts
+++ b/stores/filter-store.ts
@@ -3,9 +3,22 @@ import type { IJMAPClient } from '@/lib/jmap/client-interface';
 import type { FilterRule, SieveCapabilities, VacationSieveConfig } from '@/lib/jmap/sieve-types';
 import { parseScript } from '@/lib/sieve/parser';
 import { generateScript } from '@/lib/sieve/generator';
+import { countKeywordUses, renameKeywordInRules } from '@/lib/sieve/keyword-rename';
 import { filterHooks } from '@/lib/plugin-hooks';
 import { debug } from '@/lib/debug';
 
+/** What a tag rename managed to do to the filters that name the tag. */
+export interface KeywordRenameOutcome {
+  /** Filter actions rewritten to the new tag id. */
+  changed: number;
+  /**
+   * References to the old tag left in place because the script is hand-edited
+   * and is kept verbatim. The caller should tell the user, who has to fix those
+   * by hand - nothing else will.
+   */
+  unhandled: number;
+}
+
 interface SieveAccount {
   id: string;
   name: string;
@@ -31,6 +44,7 @@ interface FilterStore {
   fetchFilters: (client: IJMAPClient, accountId?: string) => Promise<void>;
   selectAccount: (client: IJMAPClient, accountId: string) => Promise<void>;
   saveFilters: (client: IJMAPClient) => Promise<void>;
+  renameKeywordInFilters: (client: IJMAPClient, oldId: string, newId: string) => Promise<KeywordRenameOutcome>;
   validateScript: (client: IJMAPClient, content: string) => Promise<{ isValid: boolean; errors?: string[] }>;
   addRule: (rule: FilterRule) => void;
   updateRule: (ruleId: string, updates: Partial<FilterRule>) => void;
@@ -176,6 +190,85 @@ export const useFilterStore = create<FilterStore>()((set, get) => ({
     }
   },
 
+  /**
+   * Follows a renamed tag into this account's filters.
+   *
+   * Renaming a tag changes its id, and therefore the `$label:` keyword a rule
+   * writes. Migrating only the messages (`migrateKeyword`) would leave the rule
+   * tagging new mail under the old id, which nothing names any more - the rule
+   * looks broken while running exactly as written.
+   *
+   * The script is fetched and written back on its own rather than through
+   * `fetchFilters`/`saveFilters`, so a rename from the tag settings never
+   * disturbs which account an open filter view is showing. That view is updated
+   * in place when it happens to be showing this same account.
+   *
+   * A hand-edited (opaque) script is left alone - it has no parsed rules to
+   * rewrite and re-generating it would discard the user's own Sieve - and its
+   * remaining references are reported instead. Upload failures propagate.
+   */
+  renameKeywordInFilters: async (client, oldId, newId) => {
+    const nothing: KeywordRenameOutcome = { changed: 0, unhandled: 0 };
+    if (!oldId || !newId || oldId === newId) return nothing;
+    if (!client.supportsSieve()) return nothing;
+
+    // The account that runs the rules. A rule can only tag mail arriving in
+    // its own account, so this is the one to rewrite even in a session where
+    // the Sieve and mail primaries are different accounts - which RFC 8620
+    // permits, and which the caller's message migration, bound to the mail
+    // primary, would not have covered anyway.
+    const accountId = client.getSieveAccountId();
+    const scripts = (await client.getSieveScripts(accountId)).filter(s => s.name !== 'vacation');
+    const activeScript = scripts.find(s => s.isActive);
+    if (!activeScript) {
+      // Nothing is filtering mail right now. Rewriting an inactive script would
+      // mean activating it - updateSieveScript activates on write - and a tag
+      // rename must not switch someone's filters back on.
+      return nothing;
+    }
+
+    const content = await client.getSieveScriptContent(activeScript.blobId, accountId);
+    const parsed = parseScript(content);
+    if (parsed.isOpaque) {
+      return { changed: 0, unhandled: countKeywordUses(content, oldId) };
+    }
+
+    const { rules, changed } = renameKeywordInRules(parsed.rules, oldId, newId);
+    if (changed === 0) return { changed: 0, unhandled: countKeywordUses(content, oldId) };
+
+    let script = generateScript(rules, parsed.vacation || undefined, {
+      externalRequires: parsed.externalRequires,
+    });
+    // Same plugin pipeline a normal save runs through: a plugin's managed
+    // section is grafted on at generate time, so skipping the transform here
+    // would drop it from the script this write makes active.
+    const transformed = await filterHooks.onSieveScriptGenerate.transform(script, { accountId });
+    if (typeof transformed === 'string' && transformed.trim().length > 0) {
+      script = transformed;
+    }
+
+    // Count what still names the old tag in the script actually being written,
+    // after the plugin transform: a rule kept verbatim, a test comparing
+    // against the keyword, or a section a plugin just grafted back on.
+    const unhandled = countKeywordUses(script, oldId);
+
+    await client.updateSieveScript(activeScript.id, script, true, accountId);
+    debug.log('filters', 'Renamed tag in', changed, 'filter action(s)');
+
+    const state = get();
+    if (state.selectedAccountId === accountId && !state.isOpaque) {
+      set({
+        rules,
+        rawScript: script,
+        activeScriptId: activeScript.id,
+        vacationSettings: parsed.vacation || null,
+        externalRequires: parsed.externalRequires,
+      });
+    }
+    void filterHooks.onSieveScriptChange.emit({ accountId, script });
+    return { changed, unhandled };
+  },
+
   validateScript: async (client, content) => {
     return client.validateSieveScript(content, get().selectedAccountId || undefined);
   },