diff --git a/src/browser/js/Local.zig b/src/browser/js/Local.zig
index a45b35df..f913dafd 100644
--- a/src/browser/js/Local.zig
+++ b/src/browser/js/Local.zig
@@ -1212,6 +1212,12 @@ pub fn rejectPromise(self: *const Local, value: anytype) !js.Promise {
     return resolver.promise();
 }
 
+pub fn rejectErrorPromise(self: *const Local, value: js.PromiseResolver.RejectError) !js.Promise {
+    var resolver = js.PromiseResolver.init(self);
+    resolver.rejectError("Local.rejectPromise", value);
+    return resolver.promise();
+}
+
 pub fn resolvePromise(self: *const Local, value: anytype) !js.Promise {
     var resolver = js.PromiseResolver.init(self);
     resolver.resolve("Local.resolvePromise", value);
diff --git a/src/browser/js/PromiseResolver.zig b/src/browser/js/PromiseResolver.zig
index 67f04311..6386569a 100644
--- a/src/browser/js/PromiseResolver.zig
+++ b/src/browser/js/PromiseResolver.zig
@@ -18,7 +18,9 @@
 
 const js = @import("js.zig");
 const v8 = js.v8;
+
 const log = @import("../../log.zig");
+const DOMException = @import("../webapi/DOMException.zig");
 
 const PromiseResolver = @This();
 
@@ -63,14 +65,19 @@ pub fn reject(self: PromiseResolver, comptime source: []const u8, value: anytype
     };
 }
 
-const RejectError = union(enum) {
+pub const RejectError = union(enum) {
     generic: []const u8,
     type_error: []const u8,
+    dom_exception: anyerror,
 };
 pub fn rejectError(self: PromiseResolver, comptime source: []const u8, err: RejectError) void {
     const handle = switch (err) {
         .type_error => |str| self.local.isolate.createTypeError(str),
         .generic => |str| self.local.isolate.createError(str),
+        .dom_exception => |exception| {
+            self.reject(source, DOMException.fromError(exception));
+            return;
+        },
     };
     self._reject(js.Value{ .handle = handle, .local = self.local }) catch |reject_err| {
         log.err(.bug, "rejectError", .{ .source = source, .err = reject_err, .persistent = false });
diff --git a/src/browser/js/bridge.zig b/src/browser/js/bridge.zig
index 1b035837..dd9a81b4 100644
--- a/src/browser/js/bridge.zig
+++ b/src/browser/js/bridge.zig
@@ -726,7 +726,6 @@ pub const JsApis = flattenTypes(&.{
     @import("../webapi/Console.zig"),
     @import("../webapi/Crypto.zig"),
     @import("../webapi/Permissions.zig"),
-    @import("../webapi/Permissions.zig").PermissionStatus,
     @import("../webapi/StorageManager.zig"),
     @import("../webapi/CSS.zig"),
     @import("../webapi/css/CSSRule.zig"),
diff --git a/src/browser/tests/window/navigator.html b/src/browser/tests/navigator/navigator.html
similarity index 56%
rename from src/browser/tests/window/navigator.html
rename to src/browser/tests/navigator/navigator.html
index df9f436a..b82c6e38 100644
--- a/src/browser/tests/window/navigator.html
+++ b/src/browser/tests/navigator/navigator.html
@@ -27,3 +27,44 @@
   testing.expectEqual(false, navigator.javaEnabled());
   testing.expectEqual(false, navigator.webdriver);
 </script>
+
+<script id=permission_query>
+    testing.async(async (restore) => {
+      const p = navigator.permissions.query({ name: 'notifications' });
+      testing.expectTrue(p instanceof Promise);
+      const status = await p;
+      restore();
+      testing.expectEqual('prompt', status.state);
+      testing.expectEqual('notifications', status.name);
+  });
+</script>
+
+<script id=storage_estimate>
+  testing.async(async (restore) => {
+    const p = navigator.storage.estimate();
+    testing.expectTrue(p instanceof Promise);
+
+    const estimate = await p;
+    restore();
+    testing.expectEqual(0, estimate.usage);
+    testing.expectEqual(1024 * 1024 * 1024, estimate.quota);
+  });
+</script>
+
+<script id=deviceMemory>
+  testing.expectEqual(8, navigator.deviceMemory);
+</script>
+
+<script id=getBattery>
+  testing.async(async (restore) => {
+    const p = navigator.getBattery();
+    try {
+      await p;
+      testing.fail('getBattery should reject');
+    } catch (err) {
+      restore();
+      testing.expectEqual('NotSupportedError', err.name);
+    }
+  });
+</script>
+
diff --git a/src/browser/tests/navigator/permissions.html b/src/browser/tests/navigator/permissions.html
deleted file mode 100644
index befecf8b..00000000
--- a/src/browser/tests/navigator/permissions.html
+++ /dev/null
@@ -1,37 +0,0 @@
-<!DOCTYPE html>
-<html><body>
-<script id=permissions_query_returns_promise>
-  const p = navigator.permissions.query({ name: 'notifications' });
-  console.assert(p instanceof Promise, 'permissions.query must return a Promise');
-  p.then(status => {
-    console.assert(typeof status.state === 'string', 'state must be a string');
-    console.assert(
-      ['granted','denied','prompt'].includes(status.state),
-      'state must be valid'
-    );
-  });
-</script>
-
-<script id=storage_estimate_returns_promise>
-  const p = navigator.storage.estimate();
-  console.assert(p instanceof Promise, 'storage.estimate must return a Promise');
-  p.then(e => {
-    console.assert(typeof e.quota === 'number', 'quota must be a number');
-    console.assert(typeof e.usage === 'number', 'usage must be a number');
-  });
-</script>
-
-<script id=device_memory_is_number>
-  console.assert(
-    typeof navigator.deviceMemory === 'number',
-    'deviceMemory must be a number, got: ' + typeof navigator.deviceMemory
-  );
-  console.assert(navigator.deviceMemory > 0, 'deviceMemory must be positive');
-</script>
-
-<script id=get_battery_returns_rejected_promise>
-  const p = navigator.getBattery();
-  console.assert(p instanceof Promise, 'getBattery must return a Promise');
-  p.catch(e => console.log('getBattery correctly rejected:', e));
-</script>
-</body></html>
diff --git a/src/browser/webapi/Navigator.zig b/src/browser/webapi/Navigator.zig
index 36d32f1e..83b883b1 100644
--- a/src/browser/webapi/Navigator.zig
+++ b/src/browser/webapi/Navigator.zig
@@ -27,8 +27,8 @@ const StorageManager = @import("StorageManager.zig");
 const Navigator = @This();
 _pad: bool = false,
 _plugins: PluginArray = .{},
-_permissions: Permissions = Permissions.init,
-_storage: StorageManager = StorageManager.init,
+_permissions: Permissions = .{},
+_storage: StorageManager = .{},
 
 pub const init: Navigator = .{};
 
@@ -70,7 +70,7 @@ pub fn getStorage(self: *Navigator) *StorageManager {
 pub fn getBattery(_: *const Navigator, page: *Page) !js.Promise {
     // Battery API is not supported in headless mode.
     // Return a rejected Promise — callers must .catch() this.
-    return js.Promise.reject(error.NotSupportedError, page);
+    return page.js.local.?.rejectErrorPromise(.{ .dom_exception = error.NotSupported });
 }
 
 pub fn registerProtocolHandler(_: *const Navigator, scheme: []const u8, url: [:0]const u8, page: *const Page) !void {
@@ -179,3 +179,8 @@ pub const JsApi = struct {
     pub const permissions = bridge.accessor(Navigator.getPermissions, null, .{});
     pub const storage = bridge.accessor(Navigator.getStorage, null, .{});
 };
+
+const testing = @import("../../testing.zig");
+test "WebApi: Navigator" {
+    try testing.htmlRunner("navigator", .{});
+}
diff --git a/src/browser/webapi/Permissions.zig b/src/browser/webapi/Permissions.zig
index 5f5954b3..ee197d3f 100644
--- a/src/browser/webapi/Permissions.zig
+++ b/src/browser/webapi/Permissions.zig
@@ -1,28 +1,70 @@
-// src/browser/webapi/Permissions.zig
+// Copyright (C) 2023-2025 Lightpanda (Selecy SAS)
 //
-// Minimal Permissions API stub.
-// https://www.w3.org/TR/permissions/
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
 //
-// Turnstile probes: navigator.permissions.query({ name: 'notifications' })
-// It expects a Promise resolving to { state: 'granted' | 'denied' | 'prompt' }
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 const std = @import("std");
 const js = @import("../js/js.zig");
 const Page = @import("../Page.zig");
+const Session = @import("../Session.zig");
+
+const Allocator = std.mem.Allocator;
+
+pub fn registerTypes() []const type {
+    return &.{ Permissions, PermissionStatus };
+}
 
 const Permissions = @This();
 
 // Padding to avoid zero-size struct pointer collisions
 _pad: bool = false,
 
-pub const init: Permissions = .{};
-
 const QueryDescriptor = struct {
     name: []const u8,
 };
+// We always report 'prompt' (the default safe value — neither granted nor denied).
+pub fn query(_: *const Permissions, qd: QueryDescriptor, page: *Page) !js.Promise {
+    const arena = try page.getArena(.{ .debug = "PermissionStatus" });
+    errdefer page.releaseArena(arena);
+
+    const status = try arena.create(PermissionStatus);
+    status.* = .{
+        ._arena = arena,
+        ._state = "prompt",
+        ._name = try arena.dupe(u8, qd.name),
+    };
+    return page.js.local.?.resolvePromise(status);
+}
 
 const PermissionStatus = struct {
-    state: []const u8,
+    _arena: Allocator,
+    _name: []const u8,
+    _state: []const u8,
+
+    pub fn deinit(self: *PermissionStatus, _: bool, session: *Session) void {
+        session.releaseArena(self._arena);
+    }
+
+    fn getName(self: *const PermissionStatus) []const u8 {
+        return self._name;
+    }
+
+    fn getState(self: *const PermissionStatus) []const u8 {
+        return self._state;
+    }
 
     pub const JsApi = struct {
         pub const bridge = js.Bridge(PermissionStatus);
@@ -30,23 +72,14 @@ const PermissionStatus = struct {
             pub const name = "PermissionStatus";
             pub const prototype_chain = bridge.prototypeChain();
             pub var class_id: bridge.ClassId = undefined;
-            pub const empty_with_no_proto = true;
+            pub const weak = true;
+            pub const finalizer = bridge.finalizer(PermissionStatus.deinit);
         };
+        pub const name = bridge.accessor(getName, null, .{});
         pub const state = bridge.accessor(getState, null, .{});
     };
-
-    fn getState(self: *const PermissionStatus) []const u8 {
-        return self.state;
-    }
 };
 
-// query() returns a Promise<PermissionStatus>.
-// We always report 'prompt' (the default safe value — neither granted nor denied).
-pub fn query(_: *const Permissions, _: QueryDescriptor, page: *Page) !js.Promise {
-    const status = try page._factory.create(PermissionStatus{ .state = "prompt" });
-    return js.Promise.resolve(status, page);
-}
-
 pub const JsApi = struct {
     pub const bridge = js.Bridge(Permissions);
 
diff --git a/src/browser/webapi/StorageManager.zig b/src/browser/webapi/StorageManager.zig
index 280614a0..e7b95cc4 100644
--- a/src/browser/webapi/StorageManager.zig
+++ b/src/browser/webapi/StorageManager.zig
@@ -1,18 +1,51 @@
-// src/browser/webapi/StorageManager.zig
-// Minimal stub for navigator.storage
-// https://storage.spec.whatwg.org/#storagemanager
+// Copyright (C) 2023-2026 Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 const js = @import("../js/js.zig");
 const Page = @import("../Page.zig");
 
+pub fn registerTypes() []const type {
+    return &.{ StorageManager, StorageEstimate };
+}
+
 const StorageManager = @This();
+
 _pad: bool = false,
 
-pub const init: StorageManager = .{};
+pub fn estimate(_: *const StorageManager, page: *Page) !js.Promise {
+    const est = try page._factory.create(StorageEstimate{
+        ._usage = 0,
+        ._quota = 1024 * 1024 * 1024, // 1 GiB
+    });
+    return page.js.local.?.resolvePromise(est);
+}
 
 const StorageEstimate = struct {
-    quota: u64,
-    usage: u64,
+    _quota: u64,
+    _usage: u64,
+
+    fn getUsage(self: *const StorageEstimate) u64 {
+        return self._usage;
+    }
+
+    fn getQuota(self: *const StorageEstimate) u64 {
+        return self._quota;
+    }
 
     pub const JsApi = struct {
         pub const bridge = js.Bridge(StorageEstimate);
@@ -20,30 +53,12 @@ const StorageEstimate = struct {
             pub const name = "StorageEstimate";
             pub const prototype_chain = bridge.prototypeChain();
             pub var class_id: bridge.ClassId = undefined;
-            pub const empty_with_no_proto = true;
         };
         pub const quota = bridge.accessor(getQuota, null, .{});
         pub const usage = bridge.accessor(getUsage, null, .{});
     };
-
-    fn getQuota(self: *const StorageEstimate) u64 {
-        return self.quota;
-    }
-    fn getUsage(self: *const StorageEstimate) u64 {
-        return self.usage;
-    }
 };
 
-// Returns a resolved Promise<StorageEstimate> with plausible stub values.
-// quota = 1GB, usage = 0 (headless browser has no real storage)
-pub fn estimate(_: *const StorageManager, page: *Page) !js.Promise {
-    const est = try page._factory.create(StorageEstimate{
-        .quota = 1024 * 1024 * 1024, // 1 GiB
-        .usage = 0,
-    });
-    return js.Promise.resolve(est, page);
-}
-
 pub const JsApi = struct {
     pub const bridge = js.Bridge(StorageManager);
     pub const Meta = struct {