diff --git a/src/components.tsx b/src/components.tsx
index 54b7be3..dda6517 100644
--- a/src/components.tsx
+++ b/src/components.tsx
@@ -744,15 +744,21 @@ export function ViewToggle({
 export function CardTile({
   card,
   corner,
+  cornerLeft,
   footer,
+  selected,
 }: {
   card: CardRef;
   corner?: ReactNode;
+  /** Rendered top-left, e.g. a selection checkbox (see `selected`). */
+  cornerLeft?: ReactNode;
   footer?: ReactNode;
+  /** Highlights the tile and keeps `cornerLeft` visible without hovering. */
+  selected?: boolean;
 }) {
   const { open } = useClickPreview();
   return (
-    <div className="tile">
+    <div className={`tile ${selected ? "tile-selected" : ""}`}>
       <div className="tile-img-wrap">
         {card.image_uri ? (
           <img
@@ -765,6 +771,7 @@ export function CardTile({
         ) : (
           <div className="tile-noimg">{card.name}</div>
         )}
+        {cornerLeft && <div className="tile-corner-left">{cornerLeft}</div>}
         {corner && <div className="tile-corner">{corner}</div>}
       </div>
       {footer && <div className="tile-footer">{footer}</div>}
diff --git a/src/styles.css b/src/styles.css
index 92eb438..c9d401b 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -203,6 +203,13 @@ select option {
   color: var(--text);
 }
 
+input[type="checkbox"] {
+  width: 15px;
+  height: 15px;
+  accent-color: var(--accent);
+  cursor: pointer;
+}
+
 /* ============================================================
    App shell: nav rail + main
    ============================================================ */
@@ -950,6 +957,39 @@ tbody tr:hover {
   margin-right: 4px;
 }
 
+/* ============================================================
+   Bulk-selection action bar (Library tab)
+   ============================================================ */
+
+.bulk-bar {
+  display: flex;
+  align-items: center;
+  gap: 16px;
+  flex-wrap: wrap;
+  background: var(--accent-subtle);
+  border: 1px solid var(--accent-glow);
+  border-radius: var(--radius-lg);
+  padding: 10px 16px;
+  margin-bottom: 16px;
+}
+.bulk-bar-count {
+  font-weight: 700;
+  font-size: 13px;
+  color: var(--accent-hover);
+  white-space: nowrap;
+}
+.bulk-bar-actions {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  flex-wrap: wrap;
+}
+.bulk-bar-delta {
+  width: 48px;
+  text-align: center;
+  padding: 8px 4px;
+}
+
 /* ============================================================
    Filters panel
    ============================================================ */
@@ -1158,6 +1198,34 @@ tbody tr:hover {
 .tile:focus-within .tile-corner {
   opacity: 1;
 }
+.tile-corner-left {
+  position: absolute;
+  top: 8px;
+  left: 8px;
+  /* Same reasoning as .tile-corner: don't cover the card name unless the
+     tile is being interacted with — except once selected, where the
+     checkbox should stay visible so the selection is visible at a glance. */
+  opacity: 0;
+  transition: opacity 0.12s;
+}
+.tile:hover .tile-corner-left,
+.tile:focus-within .tile-corner-left,
+.tile-selected .tile-corner-left {
+  opacity: 1;
+}
+.tile-selected .tile-img {
+  box-shadow: 0 0 0 3px var(--accent), var(--shadow-md);
+}
+.tile-select {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 26px;
+  height: 26px;
+  border-radius: 999px;
+  background: rgba(0, 0, 0, 0.78);
+  backdrop-filter: blur(2px);
+}
 .tile-badge {
   background: rgba(0, 0, 0, 0.78);
   color: #fff;
diff --git a/src/views/LibraryBrowser.tsx b/src/views/LibraryBrowser.tsx
index f0223ed..27c4167 100644
--- a/src/views/LibraryBrowser.tsx
+++ b/src/views/LibraryBrowser.tsx
@@ -8,6 +8,7 @@ import {
   GroupBySelect,
   GroupMode,
   LocationField,
+  PromptDialog,
   QtyStepper,
   ViewToggle,
   groupCards,
@@ -41,6 +42,13 @@ export function LibraryBrowser() {
   const [pendingRemoval, setPendingRemoval] = useState<Set<string>>(new Set());
   const removalTimers = useRef<Map<string, ReturnType<typeof setTimeout>>>(new Map());
 
+  const [selected, setSelected] = useState<Set<string>>(new Set());
+  const [bulkDeckId, setBulkDeckId] = useState<number | "">("");
+  const [bulkDelta, setBulkDelta] = useState(1);
+  const [locationDialogOpen, setLocationDialogOpen] = useState(false);
+  const [bulkBusy, setBulkBusy] = useState(false);
+  const selectAllRef = useRef<HTMLInputElement>(null);
+
   useEffect(() => {
     api.listDecks().then(setDecks);
   }, []);
@@ -49,6 +57,23 @@ export function LibraryBrowser() {
   // an unmounted component.
   useEffect(() => () => removalTimers.current.forEach(clearTimeout), []);
 
+  // Keep selection in sync with what's actually visible — drop ids that fall
+  // out of the filtered set (filter changed, or a card's qty hit 0 and its
+  // grace period expired).
+  useEffect(() => {
+    setSelected((s) => {
+      const visible = new Set(rows.map((r) => r.oracle_id));
+      const next = new Set([...s].filter((id) => visible.has(id)));
+      return next.size === s.size ? s : next;
+    });
+  }, [rows]);
+
+  useEffect(() => {
+    if (selectAllRef.current) {
+      selectAllRef.current.indeterminate = selected.size > 0 && selected.size < rows.length;
+    }
+  }, [selected, rows]);
+
   useEffect(() => {
     const filter: LibraryFilter = {
       text: text.trim() || null,
@@ -116,6 +141,64 @@ export function LibraryBrowser() {
     }
   }
 
+  function toggleOne(oracleId: string) {
+    setSelected((s) => {
+      const next = new Set(s);
+      if (next.has(oracleId)) next.delete(oracleId);
+      else next.add(oracleId);
+      return next;
+    });
+  }
+
+  function toggleSelectAll() {
+    setSelected((s) => (s.size === rows.length ? new Set() : new Set(rows.map((r) => r.oracle_id))));
+  }
+
+  /**
+   * Set the in-deck quantity of every selected card to either 1 or the full
+   * owned count (e.g. select a handful of basic lands, "Add All" to put
+   * every copy you own into the deck at once) — overwrites the quantity for
+   * cards already in the deck rather than skipping them, so it doubles as a
+   * bulk "fix the land count" tool.
+   */
+  async function bulkAddToDeck(mode: "one" | "all") {
+    if (bulkDeckId === "") return;
+    const deck = decks.find((d) => d.id === bulkDeckId);
+    if (!deck) return;
+    setBulkBusy(true);
+    try {
+      const targets = rows.filter((r) => selected.has(r.oracle_id));
+      await Promise.all(
+        targets.map((r) =>
+          api.setDeckCard(deck.id, r.oracle_id, mode === "all" ? r.quantity_owned : 1, false),
+        ),
+      );
+      setRefreshKey((k) => k + 1);
+    } finally {
+      setBulkBusy(false);
+    }
+  }
+
+  async function bulkSetLocation(value: string) {
+    setBulkBusy(true);
+    try {
+      await Promise.all([...selected].map((id) => api.setLocation(id, value)));
+      setLocationDialogOpen(false);
+      setRefreshKey((k) => k + 1);
+    } finally {
+      setBulkBusy(false);
+    }
+  }
+
+  async function bulkAdjust(delta: number) {
+    setBulkBusy(true);
+    try {
+      await Promise.all([...selected].map((id) => adjust(id, delta)));
+    } finally {
+      setBulkBusy(false);
+    }
+  }
+
   const deckOrLocation = (c: LibraryCard) =>
     c.decks.length === 0 ? (
       <LocationField
@@ -136,6 +219,7 @@ export function LibraryBrowser() {
       <table>
         <thead>
           <tr>
+            <th></th>
             <th></th>
             <th>Colors</th>
             <th>Name</th>
@@ -148,6 +232,13 @@ export function LibraryBrowser() {
         <tbody>
           {cards.map((c) => (
             <tr key={c.oracle_id}>
+              <td>
+                <input
+                  type="checkbox"
+                  checked={selected.has(c.oracle_id)}
+                  onChange={() => toggleOne(c.oracle_id)}
+                />
+              </td>
               <td>
                 <CardThumb card={c} />
               </td>
@@ -188,6 +279,16 @@ export function LibraryBrowser() {
           <CardTile
             key={c.oracle_id}
             card={c}
+            selected={selected.has(c.oracle_id)}
+            cornerLeft={
+              <span className="tile-select">
+                <input
+                  type="checkbox"
+                  checked={selected.has(c.oracle_id)}
+                  onChange={() => toggleOne(c.oracle_id)}
+                />
+              </span>
+            }
             corner={
               <QtyStepper
                 overlay
@@ -210,15 +311,106 @@ export function LibraryBrowser() {
   return (
     <div>
       <div className="row" style={{ justifyContent: "space-between", marginBottom: 12 }}>
-        <h2 style={{ margin: 0 }}>
-          Library <span className="badge">{rows.length}</span>
-        </h2>
+        <div className="row" style={{ gap: 14 }}>
+          <label className="row" style={{ gap: 6, cursor: "pointer" }} title="Select all filtered cards">
+            <input
+              ref={selectAllRef}
+              type="checkbox"
+              checked={rows.length > 0 && selected.size === rows.length}
+              onChange={toggleSelectAll}
+              disabled={rows.length === 0}
+            />
+            <span className="muted" style={{ fontSize: 12 }}>
+              Select all
+            </span>
+          </label>
+          <h2 style={{ margin: 0 }}>
+            Library <span className="badge">{rows.length}</span>
+          </h2>
+        </div>
         <div className="row" style={{ gap: 16 }}>
           <GroupBySelect value={groupBy} onChange={setGroupBy} />
           <ViewToggle mode={view} onChange={setView} />
         </div>
       </div>
 
+      {selected.size > 0 && (
+        <div className="bulk-bar">
+          <span className="bulk-bar-count">{selected.size} selected</span>
+          <div className="bulk-bar-actions">
+            <span className="row" style={{ gap: 6 }}>
+              <select
+                value={bulkDeckId}
+                onChange={(e) => setBulkDeckId(e.target.value === "" ? "" : Number(e.target.value))}
+                disabled={bulkBusy}
+              >
+                <option value="">Add to deck…</option>
+                {decks.map((d) => (
+                  <option key={d.id} value={d.id}>
+                    {d.name}
+                  </option>
+                ))}
+              </select>
+              <button
+                onClick={() => bulkAddToDeck("one")}
+                disabled={bulkBusy || bulkDeckId === ""}
+                title="Set each selected card to 1 copy in the deck"
+              >
+                Add 1
+              </button>
+              <button
+                onClick={() => bulkAddToDeck("all")}
+                disabled={bulkBusy || bulkDeckId === ""}
+                title="Set each selected card to every copy you own"
+              >
+                Add All
+              </button>
+            </span>
+            <button onClick={() => setLocationDialogOpen(true)} disabled={bulkBusy}>
+              Set location…
+            </button>
+            <span className="row" style={{ gap: 4 }}>
+              <button
+                onClick={() => bulkAdjust(-bulkDelta)}
+                disabled={bulkBusy}
+                title="Remove copies from each selected card"
+              >
+                −
+              </button>
+              <input
+                className="bulk-bar-delta"
+                type="number"
+                min={1}
+                value={bulkDelta}
+                onChange={(e) => setBulkDelta(Math.max(1, Number(e.target.value) || 1))}
+              />
+              <button
+                onClick={() => bulkAdjust(bulkDelta)}
+                disabled={bulkBusy}
+                title="Add copies to each selected card"
+              >
+                +
+              </button>
+            </span>
+          </div>
+          <span className="spacer" />
+          <button onClick={() => setSelected(new Set())} disabled={bulkBusy}>
+            Clear
+          </button>
+        </div>
+      )}
+
+      {locationDialogOpen && (
+        <PromptDialog
+          title="Set location"
+          label={`Location for ${selected.size} card${selected.size === 1 ? "" : "s"}`}
+          defaultValue=""
+          confirmLabel="Apply"
+          onConfirm={bulkSetLocation}
+          onCancel={() => setLocationDialogOpen(false)}
+        />
+      )}
+
       <div className="filters">
         <div className="field">
           <label>Name contains</label>