diff --git a/frontend/src/__tests__/components/AssignSpoolModal.test.tsx b/frontend/src/__tests__/components/AssignSpoolModal.test.tsx
index 21098cb75..0927b0a67 100644
--- a/frontend/src/__tests__/components/AssignSpoolModal.test.tsx
+++ b/frontend/src/__tests__/components/AssignSpoolModal.test.tsx
@@ -77,19 +77,23 @@ describe('AssignSpoolModal', () => {
     expect(screen.queryByText('Assign Spool')).not.toBeInTheDocument();
   });
 
-  it('filters out Bambu Lab spools (with tag_uid/tray_uuid)', async () => {
+  // Inverted from the original "filters out BL spools" expectation in #1133.
+  // Bambu Lab spools (tag_uid + tray_uuid populated by SpoolBuddy NFC scan or
+  // auto-creation) used to be hidden from this picker, blocking the workflow
+  // where a user has a BL spool in inventory but doesn't want to scan it via
+  // SpoolBuddy each time and just wants to pick it from the list. The picker
+  // now lists every spool that isn't already assigned to another slot.
+  it('lists Bambu Lab spools (with tag_uid/tray_uuid) alongside manual ones (#1133)', async () => {
     render(<AssignSpoolModal {...defaultProps} />);
 
     await waitFor(() => {
       expect(screen.getByText(/Polymaker/)).toBeInTheDocument();
     });
 
-    // Manual spools should be visible
     expect(screen.getByText(/Polymaker/)).toBeInTheDocument();
     expect(screen.getByText(/Overture/)).toBeInTheDocument();
-
-    // BL spool should NOT be visible
-    expect(screen.queryByText(/Jade White/)).not.toBeInTheDocument();
+    // The previously-excluded BL spool is now visible.
+    expect(screen.getByText(/Jade White/)).toBeInTheDocument();
   });
 
   it('filters out spools already assigned to other slots', async () => {
@@ -125,16 +129,57 @@ describe('AssignSpoolModal', () => {
     expect(screen.getByText(/Polymaker/)).toBeInTheDocument();
   });
 
-  it('shows noManualSpools message when all spools are BL or assigned', async () => {
-    (api.getSpools as ReturnType<typeof vi.fn>).mockResolvedValue([blSpool]);
+  // Empty-state premise reworked for #1133: BL spools no longer trigger
+  // the empty state by virtue of being BL, so we exercise the only
+  // remaining trigger — every spool already taken by another slot.
+  it('shows noAvailableSpools message when every spool is already assigned elsewhere', async () => {
+    (api.getSpools as ReturnType<typeof vi.fn>).mockResolvedValue([manualSpool]);
+    (api.getAssignments as ReturnType<typeof vi.fn>).mockResolvedValue([
+      // manualSpool (id=1) is taken by a different (printer/ams/tray) tuple,
+      // so it must be filtered out of THIS slot's picker.
+      { id: 99, spool_id: 1, printer_id: 1, ams_id: 0, tray_id: 1 },
+    ]);
 
     render(<AssignSpoolModal {...defaultProps} />);
 
     await waitFor(() => {
-      expect(screen.getByText(/No manually added spools/i)).toBeInTheDocument();
+      expect(screen.getByText(/No spools available/i)).toBeInTheDocument();
     });
   });
 
+  // The toggle's label says "Show all spools" but originally only bypassed
+  // material/profile filtering — spools assigned elsewhere stayed hidden
+  // even with the toggle on. That made it impossible to recover from the
+  // case where MQTT auto-reassignment beat a manual unassign by a few
+  // milliseconds, leaving the just-freed spool in another slot's
+  // assignment row and out of reach of this picker. With the toggle on,
+  // every spool is now listed regardless of where it's currently assigned.
+  it('lists spools assigned to other slots when "Show all spools" toggle is enabled', async () => {
+    (api.getSpools as ReturnType<typeof vi.fn>).mockResolvedValue([manualSpool, anotherManualSpool]);
+    (api.getAssignments as ReturnType<typeof vi.fn>).mockResolvedValue([
+      // anotherManualSpool (id=3) is taken by a different slot.
+      { id: 99, spool_id: 3, printer_id: 1, ams_id: 0, tray_id: 1 },
+    ]);
+
+    render(<AssignSpoolModal {...defaultProps} />);
+
+    // Default state: spool 3 is hidden because it's assigned elsewhere.
+    await waitFor(() => {
+      expect(screen.getByText(/Polymaker/)).toBeInTheDocument();
+    });
+    expect(screen.queryByText(/Overture/)).not.toBeInTheDocument();
+
+    // Flip the toggle — both spools must now appear, including the one
+    // currently assigned to the other slot.
+    const toggle = screen.getByLabelText(/show all spools/i);
+    toggle.click();
+
+    await waitFor(() => {
+      expect(screen.getByText(/Overture/)).toBeInTheDocument();
+    });
+    expect(screen.getByText(/Polymaker/)).toBeInTheDocument();
+  });
+
   it('lists spool with no slicer profile when material matches the tray (#1047)', async () => {
     const spoolWithoutSlicerProfile = {
       id: 10,
diff --git a/frontend/src/__tests__/components/FilamentHoverCard.test.tsx b/frontend/src/__tests__/components/FilamentHoverCard.test.tsx
index be9f5decb..6a0cff533 100644
--- a/frontend/src/__tests__/components/FilamentHoverCard.test.tsx
+++ b/frontend/src/__tests__/components/FilamentHoverCard.test.tsx
@@ -5,7 +5,7 @@
 
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import { render, screen, fireEvent, waitFor } from '../utils';
-import { FilamentHoverCard } from '../../components/FilamentHoverCard';
+import { FilamentHoverCard, EmptySlotHoverCard } from '../../components/FilamentHoverCard';
 
 const baseFilamentData = {
   vendor: 'Bambu Lab' as const,
@@ -165,4 +165,114 @@ describe('FilamentHoverCard', () => {
       });
     });
   });
+
+  // The inventory section was previously hidden for `vendor === 'Bambu Lab'`
+  // because BL spools were assumed to be managed entirely via RFID. #1133
+  // removed that gate so users who don't want to scan via SpoolBuddy NFC
+  // can still pick a BL spool from inventory the same way they pick a
+  // third-party one.
+  describe('inventory section vendor visibility (#1133)', () => {
+    it('shows the assign-spool button on a Bambu Lab slot when the spool is unassigned', async () => {
+      const onAssign = vi.fn();
+      renderWithHover(
+        <FilamentHoverCard
+          data={{ ...baseFilamentData, vendor: 'Bambu Lab' }}
+          inventory={{ assignedSpool: null, onAssignSpool: onAssign }}
+        >
+          <div>trigger</div>
+        </FilamentHoverCard>
+      );
+      vi.advanceTimersByTime(100);
+      await waitFor(() => {
+        expect(screen.getByText(/assign/i)).toBeInTheDocument();
+      });
+    });
+
+    it('shows the unassign button on a Bambu Lab slot when an inventory spool is already assigned', async () => {
+      // Regression guard: the original gate hid BOTH the assign and unassign
+      // buttons for BL slots. A user who'd already assigned an inventory
+      // spool to a BL slot couldn't undo it without dropping into the
+      // inventory page directly.
+      const onUnassign = vi.fn();
+      renderWithHover(
+        <FilamentHoverCard
+          data={{ ...baseFilamentData, vendor: 'Bambu Lab' }}
+          inventory={{
+            assignedSpool: {
+              id: 1,
+              material: 'PLA',
+              brand: 'Devil Design',
+              color_name: 'Black',
+            },
+            onUnassignSpool: onUnassign,
+          }}
+        >
+          <div>trigger</div>
+        </FilamentHoverCard>
+      );
+      vi.advanceTimersByTime(100);
+      await waitFor(() => {
+        expect(screen.getByText(/unassign/i)).toBeInTheDocument();
+      });
+    });
+
+    it('still shows the assign-spool button for a non-Bambu vendor (no behaviour change)', async () => {
+      const onAssign = vi.fn();
+      renderWithHover(
+        <FilamentHoverCard
+          data={{ ...baseFilamentData, vendor: 'Polymaker' as unknown as 'Bambu Lab' }}
+          inventory={{ assignedSpool: null, onAssignSpool: onAssign }}
+        >
+          <div>trigger</div>
+        </FilamentHoverCard>
+      );
+      vi.advanceTimersByTime(100);
+      await waitFor(() => {
+        expect(screen.getByText(/assign/i)).toBeInTheDocument();
+      });
+    });
+  });
+});
+
+// EmptySlotHoverCard is the hover wrapper rendered for a physically empty
+// AMS slot. #1133 removed its inventory affordance: a slot with nothing
+// loaded has no spool to attach an inventory record to, and offering the
+// action there only led to users assigning the wrong spool to a slot the
+// printer hadn't actually loaded yet. The configure-slot affordance is
+// kept, since "preset for the next spool to land here" is still a sensible
+// thing to do on an empty slot.
+describe('EmptySlotHoverCard (#1133)', () => {
+  beforeEach(() => {
+    vi.useFakeTimers({ shouldAdvanceTime: true });
+  });
+
+  it('does not render an assign-spool affordance', async () => {
+    const result = render(
+      <EmptySlotHoverCard configureSlot={{ enabled: true, onConfigure: vi.fn() }}>
+        <div>trigger</div>
+      </EmptySlotHoverCard>
+    );
+    fireEvent.mouseEnter(result.container.firstElementChild as HTMLElement);
+    vi.advanceTimersByTime(100);
+    await waitFor(() => {
+      // The card itself is showing — guard the negative assertion against
+      // a card that simply never opened.
+      expect(screen.getByText(/empty/i)).toBeInTheDocument();
+    });
+    expect(screen.queryByText(/assign/i)).not.toBeInTheDocument();
+  });
+
+  it('still shows the configure button on an empty slot', async () => {
+    const onConfigure = vi.fn();
+    const result = render(
+      <EmptySlotHoverCard configureSlot={{ enabled: true, onConfigure }}>
+        <div>trigger</div>
+      </EmptySlotHoverCard>
+    );
+    fireEvent.mouseEnter(result.container.firstElementChild as HTMLElement);
+    vi.advanceTimersByTime(100);
+    await waitFor(() => {
+      expect(screen.getByText(/configure/i)).toBeInTheDocument();
+    });
+  });
 });
diff --git a/frontend/src/components/AssignSpoolModal.tsx b/frontend/src/components/AssignSpoolModal.tsx
index 7670f5a24..e196957d6 100644
--- a/frontend/src/components/AssignSpoolModal.tsx
+++ b/frontend/src/components/AssignSpoolModal.tsx
@@ -49,9 +49,22 @@ export function AssignSpoolModal({ isOpen, onClose, printerId, amsId, trayId, tr
     }
   }, [isOpen]);
 
+  // Unique cache key — different consumers of `['inventory-spools']` call
+  // `getSpools()` with different `includeArchived` arguments (InventoryPage:
+  // true, SpoolBuddyDashboard / SpoolBuddyInventoryPage: false), but they
+  // all share the same key. React Query treats them as one query and
+  // serves whichever response landed first, so a SpoolBuddy component
+  // priming the cache with the archived-excluded payload makes the picker
+  // miss spools that *are* archived OR (more subtly) miss any spool that
+  // wasn't yet present when SpoolBuddy ran its initial fetch. The picker
+  // gets its own key + a fetch-everything call so this consumer is never
+  // at the mercy of someone else's cache state. Archived spools are then
+  // explicitly excluded client-side because the backend rejects archived
+  // assignments with HTTP 400 anyway, so listing them would only let the
+  // user click a button that fails.
   const { data: spools, isLoading } = useQuery({
-    queryKey: ['inventory-spools'],
-    queryFn: () => api.getSpools(),
+    queryKey: ['inventory-spools', 'assign-modal'],
+    queryFn: () => api.getSpools(true),
     enabled: isOpen,
   });
 
@@ -137,11 +150,27 @@ export function AssignSpoolModal({ isOpen, onClose, printerId, amsId, trayId, tr
       .filter(a => !(a.printer_id === printerId && a.ams_id === amsId && a.tray_id === trayId))
       .map(a => a.spool_id)
   );
-  // External slots (amsId 254 or 255) have no RFID reader, so show all spools.
-  // AMS slots only show manual spools (no tag_uid or tray_uuid).
-  const isExternalSlot = amsId === 254 || amsId === 255;
-  const manualSpools = spools?.filter((spool: InventorySpool) =>
-    !assignedSpoolIds.has(spool.id) && (isExternalSlot || (!spool.tag_uid && !spool.tray_uuid))
+  // Show every spool that isn't already taken by another slot — including
+  // RFID-tagged Bambu Lab spools (#1133). The earlier "manual spools only"
+  // gate (tag_uid && tray_uuid both null) blocked the workflow where a
+  // user has a Bambu Lab spool in inventory but doesn't want to scan it
+  // via SpoolBuddy NFC every time and just wants to pick it from the list.
+  // External slots (amsId 254/255) have always been allowed to pick from
+  // any spool because the slot itself has no RFID reader; that
+  // distinction collapses now that AMS slots also accept any spool.
+  //
+  // The "Show all spools" toggle (disableFiltering) bypasses BOTH this
+  // gate and the material/profile filter below, making it a real escape
+  // hatch for cases where MQTT has auto-reassigned a spool to another
+  // slot a fraction of a second after a manual unassign — without this,
+  // the toggle's label is a lie ("Show all" but actually filters by
+  // assignment). The backend's assign_spool route is upsert-per-
+  // (printer, ams, tray), so picking a spool that's currently taken by
+  // a different slot creates a second assignment row; that's a foot-gun
+  // for normal flows but exactly the recovery path the toggle is for.
+  const availableSpools = spools?.filter((spool: InventorySpool) =>
+    !spool.archived_at &&
+    (disableFiltering || !assignedSpoolIds.has(spool.id))
   );
 
   // Filtering logic with toggle: search filter always applies, AMS tray profile filter is optional.
@@ -149,7 +178,7 @@ export function AssignSpoolModal({ isOpen, onClose, printerId, amsId, trayId, tr
   // tray's material (partial-match both directions — "PLA" spool accepts a "PLA Basic" slot and
   // vice versa). Manually-added inventory spools typically have no slicer_filament_name; gating
   // on strict profile equality alone hid them even when the material matched (#1047).
-  let filteredSpools = manualSpools;
+  let filteredSpools = availableSpools;
   if (!disableFiltering) {
     const trayProfile = stripProfileQualifier(normalizeValue(trayInfo?.profile));
     const trayMaterial = normalizeValue(trayInfo?.material || trayInfo?.type);
@@ -326,13 +355,31 @@ export function AssignSpoolModal({ isOpen, onClose, printerId, amsId, trayId, tr
                   </button>
                 ))}
               </div>
-            ) : manualSpools && manualSpools.length === 0 ? (
+            ) : availableSpools && availableSpools.length === 0 ? (
               <div className="text-center py-8 text-bambu-gray">
-                <p>{t('inventory.noManualSpools')}</p>
+                <p>{t('inventory.noAvailableSpools')}</p>
+                {/* Diagnostic counter — when the picker is empty, having
+                    the raw fetch / filter counts visible makes a
+                    "spool I expected to see is missing" report
+                    immediately answerable: if `total fetched` is 0 the
+                    backend / cache returned nothing; if it's > 0 then
+                    the archived / assigned-elsewhere filter ate the
+                    spool and the toggle is the right escape hatch. */}
+                {spools && (
+                  <p className="text-[10px] mt-2 opacity-60">
+                    {spools.length} fetched · {spools.filter(s => s.archived_at).length} archived ·{' '}
+                    {spools.filter(s => assignedSpoolIds.has(s.id)).length} assigned to other slots
+                  </p>
+                )}
               </div>
             ) : (
               <div className="text-center py-8 text-bambu-gray">
                 <p>{t('inventory.noSpoolsMatch')}</p>
+                {availableSpools && (
+                  <p className="text-[10px] mt-2 opacity-60">
+                    {availableSpools.length} unassigned spools — {(availableSpools.length) - (filteredSpools?.length ?? 0)} filtered by tray match. Try "Show all spools".
+                  </p>
+                )}
               </div>
             )}
           </div>
diff --git a/frontend/src/components/FilamentHoverCard.tsx b/frontend/src/components/FilamentHoverCard.tsx
index 7473b380c..3cc1a7f0c 100644
--- a/frontend/src/components/FilamentHoverCard.tsx
+++ b/frontend/src/components/FilamentHoverCard.tsx
@@ -345,8 +345,12 @@ export function FilamentHoverCard({ data, children, disabled, className = '', sp
                 </div>
               )}
 
-              {/* Inventory section - only for non-Bambu spools */}
-              {inventory && data.vendor !== 'Bambu Lab' && (
+              {/* Inventory section — shown for every vendor including
+                  Bambu Lab (#1133). The earlier "non-Bambu only" gate
+                  prevented users from manually assigning a Bambu spool
+                  in inventory to an AMS slot when they didn't want to
+                  re-scan via SpoolBuddy NFC. */}
+              {inventory && (
                 <div className="pt-2 mt-2 border-t border-bambu-dark-tertiary space-y-2">
                   {inventory.assignedSpool ? (
                     <>
@@ -468,13 +472,18 @@ interface EmptySlotHoverCardProps {
   children: ReactNode;
   className?: string;
   configureSlot?: ConfigureSlotConfig;
-  inventory?: InventoryConfig;
 }
 
 /**
- * Wrapper for empty slots - shows "Empty" on hover with optional configure button
+ * Wrapper for empty slots - shows "Empty" on hover with optional configure button.
+ *
+ * The "Assign spool" affordance was removed from empty slots in #1133: a
+ * physically empty slot has no spool to attach to, and offering the
+ * action there only led to users assigning the wrong spool to a slot
+ * the printer hadn't actually loaded yet. Assignment now requires a
+ * loaded slot (which renders FilamentHoverCard, where the button lives).
  */
-export function EmptySlotHoverCard({ children, className = '', configureSlot, inventory }: EmptySlotHoverCardProps) {
+export function EmptySlotHoverCard({ children, className = '', configureSlot }: EmptySlotHoverCardProps) {
   const { t } = useTranslation();
   const [isVisible, setIsVisible] = useState(false);
   const timeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
@@ -531,21 +540,6 @@ export function EmptySlotHoverCard({ children, className = '', configureSlot, in
                 </button>
               </div>
             )}
-            {/* Assign spool button - allows assigning inventory spool to empty slot */}
-            {inventory?.onAssignSpool && (
-              <div className="px-2 pb-2">
-                <button
-                  onClick={(e) => {
-                    e.stopPropagation();
-                    inventory.onAssignSpool?.();
-                  }}
-                  className="w-full flex items-center justify-center gap-1.5 px-2 py-1.5 text-xs font-medium rounded transition-colors bg-bambu-blue/20 hover:bg-bambu-blue/30 text-bambu-blue"
-                >
-                  <Package className="w-3.5 h-3.5" />
-                  {t('inventory.assignSpool')}
-                </button>
-              </div>
-            )}
           </div>
           <div className="
             absolute left-1/2 -translate-x-1/2 top-full w-0 h-0
diff --git a/frontend/src/i18n/locales/de.ts b/frontend/src/i18n/locales/de.ts
index f4c9ce2e5..574df11e8 100644
--- a/frontend/src/i18n/locales/de.ts
+++ b/frontend/src/i18n/locales/de.ts
@@ -3318,7 +3318,7 @@ export default {
     archive: 'Archivieren',
     restore: 'Wiederherstellen',
     noSpools: 'Noch keine Spulen. Fügen Sie Ihre erste Spule hinzu.',
-    noManualSpools: 'Keine manuell hinzugefügten Spulen verfügbar. Fügen Sie zuerst eine Spule zum Inventar hinzu.',
+    noAvailableSpools: 'Keine Spulen verfügbar. Fügen Sie eine Spule zum Inventar hinzu oder lösen Sie eine aus einem anderen Slot.',
     kProfiles: 'K-Profile',
     addKProfile: 'K-Profil hinzufügen',
     assignSpool: 'Spule zuweisen',
diff --git a/frontend/src/i18n/locales/en.ts b/frontend/src/i18n/locales/en.ts
index d0192dcae..375889636 100644
--- a/frontend/src/i18n/locales/en.ts
+++ b/frontend/src/i18n/locales/en.ts
@@ -3322,7 +3322,7 @@ export default {
     archive: 'Archive',
     restore: 'Restore',
     noSpools: 'No spools yet. Add your first spool to get started.',
-    noManualSpools: 'No manually added spools available. Add a spool to your inventory first.',
+    noAvailableSpools: 'No spools available. Add a spool to your inventory or unassign one from another slot first.',
     kProfiles: 'K-Profiles',
     addKProfile: 'Add K-Profile',
     assignSpool: 'Assign Spool',
diff --git a/frontend/src/i18n/locales/fr.ts b/frontend/src/i18n/locales/fr.ts
index 0dfd2c6ad..40dda741b 100644
--- a/frontend/src/i18n/locales/fr.ts
+++ b/frontend/src/i18n/locales/fr.ts
@@ -3239,7 +3239,7 @@ export default {
     archive: 'Archiver',
     restore: 'Restaurer',
     noSpools: 'Aucune bobine. Ajoutez votre première bobine pour commencer.',
-    noManualSpools: 'Aucune bobine manuelle disponible. Ajoutez-en une d\'abord.',
+    noAvailableSpools: 'Aucune bobine disponible. Ajoutez une bobine à votre inventaire ou désaffectez-en une d\'un autre emplacement.',
     kProfiles: 'K-Profiles',
     addKProfile: 'Ajouter K-Profile',
     assignSpool: 'Assigner Bobine',
diff --git a/frontend/src/i18n/locales/it.ts b/frontend/src/i18n/locales/it.ts
index 702af53ed..b47d26e51 100644
--- a/frontend/src/i18n/locales/it.ts
+++ b/frontend/src/i18n/locales/it.ts
@@ -3238,7 +3238,7 @@ export default {
     archive: 'Archivia',
     restore: 'Ripristina',
     noSpools: 'Ancora nessuna bobina. Aggiungi la tua prima bobina per iniziare.',
-    noManualSpools: 'Nessuna bobina aggiunta manualmente disponibile. Aggiungi prima una bobina al tuo inventario.',
+    noAvailableSpools: 'Nessuna bobina disponibile. Aggiungi una bobina al tuo inventario o rimuovine l\'assegnazione da un altro slot.',
     kProfiles: 'K-Profiles',
     addKProfile: 'Aggiungi K-Profile',
     assignSpool: 'Assegna Bobina',
diff --git a/frontend/src/i18n/locales/ja.ts b/frontend/src/i18n/locales/ja.ts
index 4ebc761c9..b068bd5ec 100644
--- a/frontend/src/i18n/locales/ja.ts
+++ b/frontend/src/i18n/locales/ja.ts
@@ -3277,7 +3277,7 @@ export default {
     archive: 'アーカイブ',
     restore: '復元',
     noSpools: 'スプールがありません。最初のスプールを追加してください。',
-    noManualSpools: '手動で追加されたスプールがありません。先にインベントリにスプールを追加してください。',
+    noAvailableSpools: '利用可能なスプールがありません。インベントリにスプールを追加するか、別のスロットからスプールの割り当てを解除してください。',
     kProfiles: 'Kプロファイル',
     addKProfile: 'Kプロファイルを追加',
     assignSpool: 'スプールを割り当て',
diff --git a/frontend/src/i18n/locales/pt-BR.ts b/frontend/src/i18n/locales/pt-BR.ts
index 624434051..e16c58f8e 100644
--- a/frontend/src/i18n/locales/pt-BR.ts
+++ b/frontend/src/i18n/locales/pt-BR.ts
@@ -3252,7 +3252,7 @@ export default {
     archive: 'Arquivar',
     restore: 'Restaurar',
     noSpools: 'Nenhum carretel ainda. Adicione seu primeiro carretel para começar.',
-    noManualSpools: 'Nenhum carretel adicionado manualmente disponível. Adicione um carretel ao seu inventário primeiro.',
+    noAvailableSpools: 'Nenhum carretel disponível. Adicione um carretel ao seu inventário ou desatribua um de outro slot primeiro.',
     kProfiles: 'K-Perfis',
     addKProfile: 'Adicionar K-Perfil',
     assignSpool: 'Atribuir Carretel',
diff --git a/frontend/src/i18n/locales/zh-CN.ts b/frontend/src/i18n/locales/zh-CN.ts
index a301466b0..27e4abad9 100644
--- a/frontend/src/i18n/locales/zh-CN.ts
+++ b/frontend/src/i18n/locales/zh-CN.ts
@@ -3304,7 +3304,7 @@ export default {
     archive: '归档',
     restore: '恢复',
     noSpools: '暂无耗材。添加您的第一个耗材开始使用。',
-    noManualSpools: '没有手动添加的耗材。请先向库存中添加耗材。',
+    noAvailableSpools: '没有可用的耗材。请先向库存中添加耗材，或从其他槽位取消分配一个耗材。',
     kProfiles: 'K 值配置',
     addKProfile: '添加 K 值配置',
     assignSpool: '分配耗材',
diff --git a/frontend/src/i18n/locales/zh-TW.ts b/frontend/src/i18n/locales/zh-TW.ts
index a1ce33339..afdb44cfd 100644
--- a/frontend/src/i18n/locales/zh-TW.ts
+++ b/frontend/src/i18n/locales/zh-TW.ts
@@ -3304,7 +3304,7 @@ export default {
     archive: '歸檔',
     restore: '恢復',
     noSpools: '尚無耗材。新增您的第一個耗材開始使用。',
-    noManualSpools: '沒有手動新增的耗材。請先向庫存中新增耗材。',
+    noAvailableSpools: '沒有可用的耗材。請先向庫存中新增耗材，或從其他槽位取消指派一個耗材。',
     kProfiles: 'K 值設定',
     addKProfile: '新增 K 值設定',
     assignSpool: '分配耗材',
diff --git a/frontend/src/pages/PrintersPage.tsx b/frontend/src/pages/PrintersPage.tsx
index 35ac7347e..7176f59d1 100644
--- a/frontend/src/pages/PrintersPage.tsx
+++ b/frontend/src/pages/PrintersPage.tsx
@@ -3554,7 +3554,7 @@ function PrinterCard({
                                               color_name: assignment.spool.color_name,
                                               remainingWeightGrams: Math.max(0, Math.round(assignment.spool.label_weight - assignment.spool.weight_used)),
                                             } : null,
-                                            onAssignSpool: filamentData.vendor !== 'Bambu Lab' ? () => setAssignSpoolModal({
+                                            onAssignSpool: () => setAssignSpoolModal({
                                               printerId: printer.id,
                                               amsId: ams.id,
                                               trayId: slotIdx,
@@ -3565,8 +3565,8 @@ function PrinterCard({
                                                 color: filamentData.colorHex || '',
                                                 location: `${getAmsLabel(ams.id, ams.tray.length)} Slot ${slotIdx + 1}`,
                                               },
-                                            }) : undefined,
-                                            onUnassignSpool: assignment && filamentData.vendor !== 'Bambu Lab' ? () => onUnassignSpool?.(printer.id, ams.id, slotIdx) : undefined,
+                                            }),
+                                            onUnassignSpool: assignment ? () => onUnassignSpool?.(printer.id, ams.id, slotIdx) : undefined,
                                           };
                                         })()}
                                         configureSlot={{
@@ -3598,18 +3598,6 @@ function PrinterCard({
                                             extruderId: mappedExtruderId,
                                           }),
                                         }}
-                                        inventory={spoolmanEnabled ? undefined : {
-                                          onAssignSpool: () => setAssignSpoolModal({
-                                            printerId: printer.id,
-                                            amsId: ams.id,
-                                            trayId: slotIdx,
-                                            trayInfo: {
-                                              type: '',
-                                              color: '',
-                                              location: `${getAmsLabel(ams.id, ams.tray.length)} Slot ${slotIdx + 1}`,
-                                            },
-                                          }),
-                                        }}
                                       >
                                         {slotVisual}
                                       </EmptySlotHoverCard>
@@ -3872,7 +3860,7 @@ function PrinterCard({
                                           color_name: assignment.spool.color_name,
                                           remainingWeightGrams: Math.max(0, Math.round(assignment.spool.label_weight - assignment.spool.weight_used)),
                                         } : null,
-                                        onAssignSpool: filamentData.vendor !== 'Bambu Lab' ? () => setAssignSpoolModal({
+                                        onAssignSpool: () => setAssignSpoolModal({
                                           printerId: printer.id,
                                           amsId: ams.id,
                                           trayId: htSlotId,
@@ -3883,8 +3871,8 @@ function PrinterCard({
                                             color: filamentData.colorHex || '',
                                             location: getAmsLabel(ams.id, ams.tray.length),
                                           },
-                                        }) : undefined,
-                                        onUnassignSpool: assignment && filamentData.vendor !== 'Bambu Lab' ? () => onUnassignSpool?.(printer.id, ams.id, htSlotId) : undefined,
+                                        }),
+                                        onUnassignSpool: assignment ? () => onUnassignSpool?.(printer.id, ams.id, htSlotId) : undefined,
                                       };
                                     })()}
                                     configureSlot={{
@@ -3916,18 +3904,6 @@ function PrinterCard({
                                         extruderId: mappedExtruderId,
                                       }),
                                     }}
-                                    inventory={spoolmanEnabled ? undefined : {
-                                      onAssignSpool: () => setAssignSpoolModal({
-                                        printerId: printer.id,
-                                        amsId: ams.id,
-                                        trayId: htSlotId,
-                                        trayInfo: {
-                                          type: '',
-                                          color: '',
-                                          location: getAmsLabel(ams.id, ams.tray.length),
-                                        },
-                                      }),
-                                    }}
                                   >
                                     {slotVisual}
                                   </EmptySlotHoverCard>
@@ -4130,18 +4106,6 @@ function PrinterCard({
                                           extruderId: isDualNozzle ? (extTrayId === 254 ? 1 : 0) : undefined,
                                         }),
                                       }}
-                                      inventory={spoolmanEnabled ? undefined : {
-                                        onAssignSpool: () => setAssignSpoolModal({
-                                          printerId: printer.id,
-                                          amsId: 255,
-                                          trayId: slotTrayId,
-                                          trayInfo: {
-                                            type: '',
-                                            color: '',
-                                            location: extLabel || t('printers.external'),
-                                          },
-                                        }),
-                                      }}
                                     >
                                       {extSlotContent}
                                     </EmptySlotHoverCard>
diff --git a/frontend/src/pages/spoolbuddy/SpoolBuddyAmsPage.tsx b/frontend/src/pages/spoolbuddy/SpoolBuddyAmsPage.tsx
index 2c10a3317..d6c4c7def 100644
--- a/frontend/src/pages/spoolbuddy/SpoolBuddyAmsPage.tsx
+++ b/frontend/src/pages/spoolbuddy/SpoolBuddyAmsPage.tsx
@@ -258,7 +258,15 @@ export function SpoolBuddyAmsPage() {
     mutationFn: ({ printerId, amsId, trayId }: { printerId: number; amsId: number; trayId: number }) =>
       api.unassignSpool(printerId, amsId, trayId),
     onSuccess: () => {
+      // Two cache-key shapes coexist for spool assignments: this page and a
+      // few SpoolBuddy components key by printerId, while AssignSpoolModal
+      // (and most of Bambuddy) keys without it. Both must be invalidated
+      // here, otherwise after a SpoolBuddy unassign the modal opens with a
+      // stale assignments list, sees the just-freed spool as still taken,
+      // filters it out, and shows "no spools available" — even though it's
+      // sitting in inventory ready to re-assign (#1133 follow-up).
       queryClient.invalidateQueries({ queryKey: ['spool-assignments', selectedPrinterId] });
+      queryClient.invalidateQueries({ queryKey: ['spool-assignments'] });
       showToast(t('inventory.unassignSuccess', 'Spool unassigned'), 'success');
       setSlotActionPicker(null);
     },
@@ -686,8 +694,14 @@ export function SpoolBuddyAmsPage() {
                   </div>
                 </button>
 
-                {/* Inventory: Assign or Unassign */}
-                {!spoolmanEnabled && (assignment ? (
+                {/* Inventory: Assign or Unassign — only when a spool is
+                    physically loaded in the slot (#1133). An empty slot
+                    has nothing to attach an inventory record to, and
+                    showing the action there only led to users assigning
+                    the wrong spool to a slot the printer hadn't actually
+                    loaded yet. handleAmsSlotClick / handleExtSlotClick
+                    both pass tray=null for empty slots. */}
+                {!spoolmanEnabled && slotActionPicker?.tray && (assignment ? (
                   <button
                     onClick={handleUnassignFromPicker}
                     disabled={unassignMutation.isPending}
@@ -749,7 +763,11 @@ export function SpoolBuddyAmsPage() {
           isOpen={!!assignSpoolModal}
           onClose={() => {
             setAssignSpoolModal(null);
+            // Same dual-key invalidation as the unassign path — the AMS
+            // status panel reads the printerId-keyed query while the
+            // shared AssignSpoolModal reads the unkeyed one.
             queryClient.invalidateQueries({ queryKey: ['spool-assignments', selectedPrinterId] });
+            queryClient.invalidateQueries({ queryKey: ['spool-assignments'] });
           }}
           printerId={assignSpoolModal.printerId}
           amsId={assignSpoolModal.amsId}