diff --git a/src/browser/tests/storage.html b/src/browser/tests/storage.html
index cb41bb3d..53aa2f92 100644
--- a/src/browser/tests/storage.html
+++ b/src/browser/tests/storage.html
@@ -91,9 +91,9 @@
 
 <script id="localstorage_limits">
   localStorage.clear();
-  for (i = 0; i < 5; i++) {
+  for (let i = 0; i < 5; i++) {
     const v =  "v".repeat(1024 * 1024);
-    localStorage.setItem(v, v);
+    localStorage.setItem(i.toString(), v);
   }
   testing.expectError("QuotaExceededError", () => localStorage.setItem("last", "v"));
 </script>
diff --git a/src/browser/webapi/Window.zig b/src/browser/webapi/Window.zig
index f49e1f95..261a5de7 100644
--- a/src/browser/webapi/Window.zig
+++ b/src/browser/webapi/Window.zig
@@ -73,7 +73,6 @@ _model_context: ModelContext = .init,
 _screen: *Screen,
 _visual_viewport: *VisualViewport,
 _performance: Performance,
-_storage_bucket: storage.Bucket = .{},
 _cookie_store: ?*CookieStore = null,
 _on_load: ?js.Function.Global = null,
 _on_pageshow: ?js.Function.Global = null,
@@ -236,12 +235,19 @@ pub fn getPerformance(self: *Window) *Performance {
     return &self._performance;
 }
 
+fn bucketForOrigin(self: *Window) *storage.Bucket {
+    return self._frame._session.storage_shed.getOrPut(
+        self._frame._session.browser.app.allocator,
+        self._frame.js.origin.key,
+    ) catch @panic("OOM");
+}
+
 pub fn getLocalStorage(self: *Window) *storage.Lookup {
-    return &self._storage_bucket.local;
+    return &self.bucketForOrigin().local;
 }
 
 pub fn getSessionStorage(self: *Window) *storage.Lookup {
-    return &self._storage_bucket.session;
+    return &self.bucketForOrigin().session;
 }
 
 pub fn getCookieStore(self: *Window, exec: *Execution) !*CookieStore {
diff --git a/src/browser/webapi/storage/storage.zig b/src/browser/webapi/storage/storage.zig
index 396c81b9..127685fe 100644
--- a/src/browser/webapi/storage/storage.zig
+++ b/src/browser/webapi/storage/storage.zig
@@ -18,7 +18,6 @@
 
 const std = @import("std");
 const js = @import("../../js/js.zig");
-const Frame = @import("../../Frame.zig");
 
 const Allocator = std.mem.Allocator;
 
@@ -35,6 +34,7 @@ pub const Shed = struct {
         var it = self._origins.iterator();
         while (it.next()) |kv| {
             allocator.free(kv.key_ptr.*);
+            kv.value_ptr.*.deinit();
             allocator.destroy(kv.value_ptr.*);
         }
         self._origins.deinit(allocator);
@@ -42,13 +42,12 @@ pub const Shed = struct {
 
     pub fn getOrPut(self: *Shed, allocator: Allocator, origin: []const u8) !*Bucket {
         const gop = try self._origins.getOrPut(allocator, origin);
-        if (gop.found_existing) {
-            return gop.value_ptr.*;
-        }
+        if (gop.found_existing) return gop.value_ptr.*;
+        errdefer std.debug.assert(self._origins.remove(origin));
 
         const bucket = try allocator.create(Bucket);
-        errdefer allocator.free(bucket);
-        bucket.* = .{};
+        errdefer allocator.destroy(bucket);
+        bucket.* = .init(allocator);
 
         gop.key_ptr.* = try allocator.dupe(u8, origin);
         gop.value_ptr.* = bucket;
@@ -56,43 +55,85 @@ pub const Shed = struct {
     }
 };
 
-pub const Bucket = struct { local: Lookup = .{}, session: Lookup = .{} };
+pub const Bucket = struct {
+    local: Lookup,
+    session: Lookup,
+
+    pub fn init(allocator: Allocator) Bucket {
+        return .{
+            .local = .{ ._allocator = allocator },
+            .session = .{ ._allocator = allocator },
+        };
+    }
+
+    pub fn deinit(self: *Bucket) void {
+        self.local.deinit();
+        self.session.deinit();
+    }
+};
 
 pub const Lookup = struct {
     _data: std.StringHashMapUnmanaged([]const u8) = .empty,
     _size: usize = 0,
+    _allocator: Allocator,
 
     const max_size = 5 * 1024 * 1024;
 
+    pub fn deinit(self: *Lookup) void {
+        var it = self._data.iterator();
+        while (it.next()) |entry| {
+            self._allocator.free(entry.key_ptr.*);
+            self._allocator.free(entry.value_ptr.*);
+        }
+        self._data.deinit(self._allocator);
+        self._size = 0;
+    }
+
     pub fn getItem(self: *const Lookup, key_: ?[]const u8) ?[]const u8 {
         const k = key_ orelse return null;
         return self._data.get(k);
     }
 
-    pub fn setItem(self: *Lookup, key_: ?[]const u8, value: []const u8, frame: *Frame) !void {
+    pub fn setItem(self: *Lookup, key_: ?[]const u8, value: []const u8) !void {
         const k = key_ orelse return;
 
-        if (self._size + value.len > max_size) {
+        const old_len = if (self._data.get(k)) |old| old.len else 0;
+        std.debug.assert(old_len <= self._size);
+        if (self._size - old_len + value.len > max_size) {
             return error.QuotaExceeded;
         }
-        defer self._size += value.len;
 
-        const key_owned = try frame.dupeString(k);
-        const value_owned = try frame.dupeString(value);
+        if (self._data.getPtr(k)) |value_ptr| {
+            const value_owned = try self._allocator.dupe(u8, value);
+            self._size -= value_ptr.*.len;
+            self._allocator.free(value_ptr.*);
+            value_ptr.* = value_owned;
+            self._size += value.len;
+        } else {
+            const key_owned = try self._allocator.dupe(u8, k);
+            errdefer self._allocator.free(key_owned);
+            const value_owned = try self._allocator.dupe(u8, value);
+            errdefer self._allocator.free(value_owned);
 
-        const gop = try self._data.getOrPut(frame.arena, key_owned);
-        gop.value_ptr.* = value_owned;
+            try self._data.put(self._allocator, key_owned, value_owned);
+            self._size += value.len;
+        }
     }
 
     pub fn removeItem(self: *Lookup, key_: ?[]const u8) void {
         const k = key_ orelse return;
-        if (self._data.get(k)) |value| {
-            self._size -= value.len;
-            _ = self._data.remove(k);
-        }
+        const kv = self._data.fetchRemove(k) orelse return;
+        self._size -= kv.value.len;
+        self._allocator.free(kv.key);
+        self._allocator.free(kv.value);
     }
 
     pub fn clear(self: *Lookup) void {
+        var it = self._data.iterator();
+        while (it.next()) |entry| {
+            self._allocator.free(entry.key_ptr.*);
+            self._allocator.free(entry.value_ptr.*);
+        }
         self._data.clearRetainingCapacity();
         self._size = 0;
     }
diff --git a/src/mcp/tools.zig b/src/mcp/tools.zig
index 053957d8..10d8879e 100644
--- a/src/mcp/tools.zig
+++ b/src/mcp/tools.zig
@@ -980,6 +980,96 @@ test "MCP - evaluate error reporting" {
     } }, out.written());
 }
 
+test "MCP - eval: localStorage persists across navigations and is origin-scoped" {
+    defer testing.reset();
+    var out: std.io.Writer.Allocating = .init(testing.arena_allocator);
+    const server = try testLoadPage("http://localhost:9582/src/browser/tests/mcp_actions.html", &out.writer);
+    defer server.deinit();
+
+    // 1. Set a value in localStorage on localhost
+    const first =
+        \\{
+        \\  "jsonrpc": "2.0",
+        \\  "id": 1,
+        \\  "method": "tools/call",
+        \\  "params": {
+        \\    "name": "eval",
+        \\    "arguments": { "script": "localStorage.setItem('foo', 'bar'); localStorage.getItem('foo')" }
+        \\  }
+        \\}
+    ;
+    try router.handleMessage(server, testing.arena_allocator, first);
+    try testing.expectJson(.{ .id = 1, .result = .{
+        .content = &.{.{ .type = "text", .text = "bar" }},
+    } }, out.written());
+
+    // 2. Navigate to another origin (127.0.0.1)
+    out.clearRetainingCapacity();
+    const navigate_other =
+        \\{
+        \\  "jsonrpc": "2.0",
+        \\  "id": 2,
+        \\  "method": "tools/call",
+        \\  "params": {
+        \\    "name": "goto",
+        \\    "arguments": { "url": "http://127.0.0.1:9582/src/browser/tests/mcp_actions.html" }
+        \\  }
+        \\}
+    ;
+    try router.handleMessage(server, testing.arena_allocator, navigate_other);
+
+    // 3. Get the value on 127.0.0.1, verify it is null (isolated origin storage)
+    out.clearRetainingCapacity();
+    const second =
+        \\{
+        \\  "jsonrpc": "2.0",
+        \\  "id": 3,
+        \\  "method": "tools/call",
+        \\  "params": {
+        \\    "name": "eval",
+        \\    "arguments": { "script": "localStorage.getItem('foo')" }
+        \\  }
+        \\}
+    ;
+    try router.handleMessage(server, testing.arena_allocator, second);
+    try testing.expectJson(.{ .id = 3, .result = .{
+        .content = &.{.{ .type = "text", .text = "null" }},
+    } }, out.written());
+
+    // 4. Navigate back to localhost
+    out.clearRetainingCapacity();
+    const navigate_back =
+        \\{
+        \\  "jsonrpc": "2.0",
+        \\  "id": 4,
+        \\  "method": "tools/call",
+        \\  "params": {
+        \\    "name": "goto",
+        \\    "arguments": { "url": "http://localhost:9582/src/browser/tests/mcp_actions.html" }
+        \\  }
+        \\}
+    ;
+    try router.handleMessage(server, testing.arena_allocator, navigate_back);
+
+    // 5. Get the value on localhost, verify it is still 'bar'
+    out.clearRetainingCapacity();
+    const third =
+        \\{
+        \\  "jsonrpc": "2.0",
+        \\  "id": 5,
+        \\  "method": "tools/call",
+        \\  "params": {
+        \\    "name": "eval",
+        \\    "arguments": { "script": "localStorage.getItem('foo')" }
+        \\  }
+        \\}
+    ;
+    try router.handleMessage(server, testing.arena_allocator, third);
+    try testing.expectJson(.{ .id = 5, .result = .{
+        .content = &.{.{ .type = "text", .text = "bar" }},
+    } }, out.written());
+}
+
 test "MCP - Actions: click, fill, scroll, hover, press, selectOption, setChecked" {
     defer testing.reset();
     const aa = testing.arena_allocator;