diff --git a/src/browser/Frame.zig b/src/browser/Frame.zig
index ebf0b9119..9282ca0c4 100644
--- a/src/browser/Frame.zig
+++ b/src/browser/Frame.zig
@@ -988,6 +988,7 @@ fn scheduleNavigationWithArena(originator: *Frame, arena: *lp.Arena, request_url
 
     // Navigation: kill in-flight HTTP transfers, but leave WebSockets
     // alive — they're cross-document by spec.
+    target.abortDocumentLoad();
     session.browser.http_client.abortRequests(&target._http_owner);
 
     // Capture the originating frame's URL as the Referer for this
@@ -1029,7 +1030,8 @@ fn scheduleNavigationWithArena(originator: *Frame, arena: *lp.Arena, request_url
     }
 
     target._queued_navigation = qn;
-    return session.scheduleNavigation(target);
+    try session.scheduleNavigation(target);
+    target.abortedDocumentIsComplete();
 }
 
 // A script can have multiple competing navigation events, say it starts off
@@ -1097,13 +1099,16 @@ pub fn stopLoading(self: *Frame) void {
         self.child_frames.items[i].stopLoading();
     }
 
-    if (self._queued_navigation) |qn| {
-        const queued = self.page.queued_navigation;
-        if (std.mem.indexOfScalar(*Frame, queued.items, self)) |idx| {
-            _ = queued.swapRemove(idx);
-        }
-        qn.arena.release();
-        self._queued_navigation = null;
+    self.cancelQueuedNavigation();
+
+    // HTML's "active parser was aborted" flag. Stopping is the only thing that
+    // actually kills the parser: a merely *scheduled* navigation leaves it
+    // running until the replacement commits, and Chrome keeps honouring
+    // document.write until then.
+    if (self.parserIsRunning()) {
+        self.document._active_parser_aborted = true;
+    } else if (self.document._script_created_parser) |parser| {
+        if (parser.handle != null) self.document._active_parser_aborted = true;
     }
 
     const http_client = &self._session.browser.http_client;
@@ -1115,8 +1120,79 @@ pub fn stopLoading(self: *Frame) void {
     http_client.cancelRequests(&self._http_owner);
 }
 
+// A cross-document navigation has been scheduled (or started) for this frame:
+// its current document is superseded and must never fire DOMContentLoaded or
+// load, even if the replacement is discarded or fails. Deliberately does NOT
+// touch _load_state — the parser can still be on the stack, and open/write/
+// maybeCheckpoint key off it.
+pub fn abortDocumentLoad(self: *Frame) void {
+    self.document._load_aborted = true;
+}
+
+// The navigation parser is on the stack, i.e. an inline script is running from
+// inside parser.parse(). Narrower than `_load_state == .parsing`, which stays
+// true through deferred and async scripts.
+fn parserIsRunning(self: *const Frame) bool {
+    return switch (self._parse_state) {
+        .html => true,
+        else => false,
+    };
+}
+
+// Chrome moves a superseded document's readyState to "complete" but never
+// fires DOMContentLoaded or load. `_load_aborted` suppresses the events; this
+// is the readyState half, run as soon as the navigation is scheduled. The
+// guard makes it idempotent: a handler that renavigates lands here again.
+pub fn abortedDocumentIsComplete(self: *Frame) void {
+    if (self.document._ready_state == .complete) {
+        return;
+    }
+    self.document._ready_state = .complete;
+    self.dispatchReadyStateChange() catch |err| switch (err) {
+        error.JsException => {}, // already logged
+        else => log.err(.frame, "aborted document is complete", .{ .err = err, .type = self._type, .url = self.url }),
+    };
+}
+
+fn loadEventsAborted(self: *const Frame) bool {
+    if (self.document._load_aborted or self.js.env.terminatePending()) return true;
+    const parent = self.parent orelse return false;
+    return parent.loadEventsAborted();
+}
+
+pub fn cancelQueuedNavigation(self: *Frame) void {
+    const qn = self._queued_navigation orelse return;
+    const queued = self.page.queued_navigation;
+    if (std.mem.indexOfScalar(*Frame, queued.items, self)) |idx| {
+        _ = queued.swapRemove(idx);
+    }
+    qn.arena.release();
+    self._queued_navigation = null;
+
+    // Our own load is aborted and the replacement that would have completed it
+    // is now gone, so _documentIsComplete will never reach the parent. Release
+    // the parent's load delay here or it waits forever.
+    if (self.document._load_aborted) {
+        self.releaseParentLoadDelay();
+    }
+}
+
+// Stop delaying the parent's load event without dispatching the iframe
+// element's load event: that event belongs to a document that actually
+// finished loading, and this one never will.
+fn releaseParentLoadDelay(self: *Frame) void {
+    const parent = self.parent orelse return;
+    if (self._parent_notified) {
+        return;
+    }
+    self._parent_notified = true;
+    if (self._delays_parent_load) {
+        parent.pendingLoadCompleted();
+    }
+}
+
 pub fn documentIsLoaded(self: *Frame) void {
-    if (self._load_state != .parsing) {
+    if (self._load_state != .parsing or self.loadEventsAborted()) {
         // Ideally, documentIsLoaded would only be called once, but if a
         // script is dynamically added from an async script after
         // documentIsLoaded is already called, then ScriptManager will call
@@ -1134,6 +1210,7 @@ pub fn documentIsLoaded(self: *Frame) void {
 
 fn _documentIsLoaded(self: *Frame) !void {
     try self.dispatchReadyStateChange();
+    if (self.loadEventsAborted()) return;
 
     const event = try Event.initTrusted(.wrap("DOMContentLoaded"), .{ .bubbles = true }, self.page);
     try self._event_manager.dispatch(
@@ -1225,6 +1302,7 @@ pub fn documentIsComplete(self: *Frame) void {
     // documentIsLoaded, if there were _only_ async scripts
     if (self._load_state == .parsing) {
         self.documentIsLoaded();
+        if (self._load_state == .complete) return;
     }
 
     self._load_state = .complete;
@@ -1233,18 +1311,23 @@ pub fn documentIsComplete(self: *Frame) void {
         else => log.err(.frame, "document is complete", .{ .err = err, .type = self._type, .url = self.url }),
     };
 
-    if (self._maybe_meta_refresh) {
+    if (self._maybe_meta_refresh and !self.loadEventsAborted()) {
         self._maybe_meta_refresh = false;
         self.metaRefreshOnLoad();
     }
 }
 
 fn _documentIsComplete(self: *Frame) !void {
-    self.document._ready_state = .complete;
-    try self.dispatchReadyStateChange();
+    // abortedDocumentIsComplete may already have done this half.
+    if (self.document._ready_state != .complete) {
+        self.document._ready_state = .complete;
+        try self.dispatchReadyStateChange();
+    }
+    if (self.loadEventsAborted()) return;
 
     // Run element load/error events before window.load.
     try self.dispatchQueuedEvents();
+    if (self.loadEventsAborted()) return;
 
     // Dispatch window.load event.
     const window_target = self.window.asEventTarget();
@@ -3790,6 +3873,177 @@ test "Page: isSameOrigin" {
     try testing.expectEqual(false, frame.isSameOrigin("//origin.com/foo"));
 }
 
+test "Frame: superseded documents omit DOMContentLoaded and load" {
+    const cases = [_]struct { trigger: []const u8, expected: []const u8 }{
+        .{ .trigger = "location.assign('/next');", .expected = "complete" },
+        .{
+            .trigger = "document.addEventListener('readystatechange', () => { if (document.readyState === 'interactive') location.assign('/next'); });",
+            .expected = "interactive|complete",
+        },
+        .{
+            .trigger = "document.addEventListener('DOMContentLoaded', () => location.assign('/next'));",
+            .expected = "interactive|dcl|complete",
+        },
+        .{
+            .trigger = "document.addEventListener('readystatechange', () => { if (document.readyState === 'complete') location.assign('/next'); });",
+            .expected = "interactive|dcl|complete",
+        },
+        .{ .trigger = "location.hash = 'section';", .expected = "interactive|dcl|complete|load" },
+        .{ .trigger = "history.replaceState({}, '', '?same-document=1');", .expected = "interactive|dcl|complete|load" },
+    };
+    for (cases) |case| {
+        const page = try testing.pageTest("hi.html", .{});
+        defer page.close();
+        const frame = page.frame().?;
+        var ls: JS.Local.Scope = undefined;
+        frame.js.localScope(&ls);
+        defer ls.deinit();
+        try ls.local.eval(
+            \\globalThis.events = [];
+            \\document.addEventListener('readystatechange', () => events.push(document.readyState));
+            \\document.addEventListener('DOMContentLoaded', () => events.push('dcl'));
+            \\window.addEventListener('load', () => events.push('load'));
+        , null);
+        frame._load_state = .parsing;
+        frame.document._ready_state = .loading;
+        try ls.local.eval(case.trigger, null);
+        frame.documentIsComplete();
+        const events = try ls.local.exec("events.join('|')", null);
+        try testing.expectEqual(case.expected, try events.toStringSlice());
+    }
+}
+
+test "Frame: pending or discarded replacements do not resume old load events" {
+    for ([_]bool{ false, true }) |discard| {
+        const page = try testing.pageTest("hi.html", .{});
+        defer page.close();
+        const frame = page.frame().?;
+        var ls: JS.Local.Scope = undefined;
+        frame.js.localScope(&ls);
+        defer ls.deinit();
+        try ls.local.eval(
+            \\globalThis.events = [];
+            \\document.addEventListener('readystatechange', () => events.push(document.readyState));
+            \\document.addEventListener('DOMContentLoaded', () => events.push('dcl'));
+            \\window.addEventListener('load', () => events.push('load'));
+        , null);
+        frame._load_state = .parsing;
+        frame.document._ready_state = .loading;
+        try frame._session.initiateRootNavigation(frame._frame_id, "http://127.0.0.1:9582/src/browser/tests/hi.html?replacement", .{});
+        const replacement = frame.page.replacement.?;
+        if (discard) frame._session.discardPendingPage(replacement);
+        try testing.expectEqual(null, frame._queued_navigation);
+        frame.documentIsComplete();
+        const events = try ls.local.exec("events.join('|')", null);
+        try testing.expectEqual("complete", try events.toStringSlice());
+        if (!discard) frame._session.discardPendingPage(replacement);
+    }
+}
+
+test "Frame: readystatechange during an aborted load may renavigate or throw" {
+    const page = try testing.pageTest("hi.html", .{});
+    defer page.close();
+    const frame = page.frame().?;
+    var ls: JS.Local.Scope = undefined;
+    frame.js.localScope(&ls);
+    defer ls.deinit();
+    try ls.local.eval(
+        \\globalThis.events = [];
+        \\document.addEventListener('readystatechange', () => {
+        \\  events.push(document.readyState);
+        \\  if (document.readyState === 'complete') { location.assign('/second'); throw new Error('handler'); }
+        \\});
+        \\window.addEventListener('load', () => events.push('load'));
+    , null);
+    frame._load_state = .parsing;
+    frame.document._ready_state = .loading;
+    testing.silenceLog(&.{ .js, .event, .frame });
+    try ls.local.eval("location.assign('/first');", null);
+    try testing.expectEqual("complete", try (try ls.local.exec("events.join('|')", null)).toStringSlice());
+    try testing.expectEqual(true, std.mem.endsWith(u8, frame._queued_navigation.?.url, "/second"));
+    try testing.expectEqual(1, frame.page.queued_navigation.items.len);
+    frame.documentIsComplete();
+    try testing.expectEqual("complete", try (try ls.local.exec("events.join('|')", null)).toStringSlice());
+}
+
+test "Frame: document.open cancels the queued navigation without reviving load" {
+    const page = try testing.pageTest("hi.html", .{});
+    defer page.close();
+    const frame = page.frame().?;
+    var ls: JS.Local.Scope = undefined;
+    frame.js.localScope(&ls);
+    defer ls.deinit();
+    try ls.local.eval(
+        \\globalThis.events = [];
+        \\window.addEventListener('load', () => events.push('load'));
+        \\location.assign('/next');
+        \\document.open();
+        \\document.write('<title>Rewritten</title>');
+        \\document.close();
+    , null);
+    try testing.expectEqual(null, frame._queued_navigation);
+    try testing.expectEqual(0, frame.page.queued_navigation.items.len);
+    try testing.expectEqual("Rewritten", try (try ls.local.exec("document.title", null)).toStringSlice());
+    try testing.expectEqual("", try (try ls.local.exec("events.join('|')", null)).toStringSlice());
+}
+
+test "Frame: document.open after inline navigation does not restart the parser" {
+    const page = try testing.pageTest("fixtures/navigation_open.html", .{});
+    defer page.close();
+
+    try testing.expect(std.mem.endsWith(u8, page.frame().?.url, "/hi.html"));
+}
+
+test "Frame: document.open can cancel navigation once parsing has finished" {
+    inline for (.{ "?interactive", "?dcl" }) |query| {
+        const page = try testing.pageTest("fixtures/navigation_open.html" ++ query, .{});
+        defer page.close();
+        const frame = page.frame().?;
+
+        try testing.expect(std.mem.endsWith(u8, frame.url, "/navigation_open.html" ++ query));
+        try testing.expectEqual(false, frame.document._active_parser_aborted);
+        try testing.expectEqual(null, frame._queued_navigation);
+        try testing.expectEqual("Rewritten", (try frame.getTitle()).?);
+    }
+}
+
+test "Frame: a scheduled navigation does not abort the parser" {
+    const page = try testing.pageTest("fixtures/navigation_open.html?write", .{});
+    defer page.close();
+    const frame = page.frame().?;
+
+    try testing.expect(std.mem.endsWith(u8, frame.url, "/navigation_open.html?write"));
+    var ls: JS.Local.Scope = undefined;
+    frame.js.localScope(&ls);
+    defer ls.deinit();
+    // The write landed: only window.stop() sets the active-parser-was-aborted
+    // flag, scheduling the navigation doesn't.
+    const late = try ls.local.exec("document.getElementById('late').textContent", null);
+    try testing.expectEqual("late", try late.toStringSlice());
+    try testing.expectEqual(true, frame.document._active_parser_aborted);
+}
+
+test "Frame: cancelling navigation does not revive an aborted parser" {
+    const page = try testing.pageTest("fixtures/navigation_open.html?cancel", .{});
+    defer page.close();
+    const frame = page.frame().?;
+
+    try testing.expect(std.mem.endsWith(u8, frame.url, "/navigation_open.html?cancel"));
+    var ls: JS.Local.Scope = undefined;
+    frame.js.localScope(&ls);
+    defer ls.deinit();
+    // The original parse has unwound, but the active-parser-was-aborted flag
+    // must still prevent open/write/writeln from replacing the document.
+    try ls.local.eval(
+        \\document.open();
+        \\document.write('<title>Later write</title>');
+        \\document.writeln('<title>Later writeln</title>');
+        \\document.close();
+    , null);
+    try testing.expectEqual("Original", try (try ls.local.exec("document.title", null)).toStringSlice());
+    try testing.expectEqual(null, frame.document._script_created_parser);
+}
+
 test "Frame: static immediate meta refresh navigates" {
     const page = try testing.pageTest("fixtures/meta_refresh.html", .{});
     defer page.close();
diff --git a/src/browser/Runner.zig b/src/browser/Runner.zig
index 2f0820fd0..e85dc09b4 100644
--- a/src/browser/Runner.zig
+++ b/src/browser/Runner.zig
@@ -559,6 +559,25 @@ test "Runner: lazy iframe does not delay the load event" {
     try testing.expectEqual(true, lazy_child._parent_notified);
 }
 
+test "Runner: iframe that cancels its own navigation stops delaying the parent" {
+    const page = try testing.pageTest("runner/iframe_nav_cancel.html", .{ .wait_until_done = false });
+    defer page.close();
+
+    var runner = page.session.runner(.{});
+    try runner.waitForFrame(page.frame_id, 2000, .{ .until = .load });
+
+    const frame = page.frame().?;
+    try testing.expectEqual(true, frame._load_state == .complete);
+    try testing.expectEqual(0, frame._pending_loads);
+
+    // The child aborted its load for a navigation it then cancelled, so no
+    // replacement frame will ever notify the parent on its behalf.
+    const child = frame.child_frames.items[0];
+    try testing.expectEqual(true, child.document._load_aborted);
+    try testing.expectEqual(null, child._queued_navigation);
+    try testing.expectEqual(true, child._parent_notified);
+}
+
 test "Runner: idle notifications advance past a resolved condition" {
     const page = try testing.pageTest("runner/runner1.html", .{});
     defer page.close();
diff --git a/src/browser/Session.zig b/src/browser/Session.zig
index b0998fbec..f885095a0 100644
--- a/src/browser/Session.zig
+++ b/src/browser/Session.zig
@@ -904,6 +904,9 @@ pub fn initiateRootNavigation(self: *Session, frame_id: u32, url: [:0]const u8,
         log.err(.browser, "pending navigation start", .{ .err = err, .url = url });
         return err;
     };
+
+    live.frame.abortDocumentLoad();
+    live.frame.abortedDocumentIsComplete();
 }
 
 // Promote a pending replacement Page to be the live Page.
diff --git a/src/browser/tests/fixtures/navigation_open.html b/src/browser/tests/fixtures/navigation_open.html
new file mode 100644
index 000000000..0ad8d2750
--- /dev/null
+++ b/src/browser/tests/fixtures/navigation_open.html
@@ -0,0 +1,28 @@
+<!doctype html>
+<title>Original</title>
+<script>
+function navigateAndOpen() {
+  location.assign('../hi.html');
+  if (location.search === '?cancel') window.stop();
+  document.open();
+  document.write('<title>Rewritten</title>');
+  document.close();
+}
+
+if (location.search === '?interactive') {
+  document.addEventListener('readystatechange', () => {
+    if (document.readyState === 'interactive') navigateAndOpen();
+  });
+} else if (location.search === '?dcl') {
+  document.addEventListener('DOMContentLoaded', navigateAndOpen);
+} else if (location.search === '?write') {
+  // Scheduling a navigation does not abort the parser: Chrome keeps honouring
+  // document.write until the replacement commits. window.stop() cancels the
+  // navigation so the test can see what landed.
+  location.assign('../hi.html');
+  document.write('<p id="late">late</p>');
+  window.stop();
+} else {
+  navigateAndOpen();
+}
+</script>
diff --git a/src/browser/tests/runner/iframe_nav_cancel.html b/src/browser/tests/runner/iframe_nav_cancel.html
new file mode 100644
index 000000000..1b3a6e50f
--- /dev/null
+++ b/src/browser/tests/runner/iframe_nav_cancel.html
@@ -0,0 +1,3 @@
+<!DOCTYPE html>
+<meta charset="UTF-8">
+<iframe src="iframe_nav_cancel_child.html"></iframe>
diff --git a/src/browser/tests/runner/iframe_nav_cancel_child.html b/src/browser/tests/runner/iframe_nav_cancel_child.html
new file mode 100644
index 000000000..2645550af
--- /dev/null
+++ b/src/browser/tests/runner/iframe_nav_cancel_child.html
@@ -0,0 +1,7 @@
+<!doctype html>
+<script>
+// Abort our own load for a navigation, then cancel the navigation. Nothing
+// will ever complete this document, so it must stop delaying the parent.
+location.assign('runner1.html');
+window.stop();
+</script>
diff --git a/src/browser/webapi/Document.zig b/src/browser/webapi/Document.zig
index c9ba54688..0a283a8e2 100644
--- a/src/browser/webapi/Document.zig
+++ b/src/browser/webapi/Document.zig
@@ -65,6 +65,9 @@ _content_type: ?[]const u8 = null,
 // createDocument) are UTF-8 regardless of the frame's encoding
 _charset: ?[]const u8 = null,
 _ready_state: ReadyState = .loading,
+_load_aborted: bool = false,
+// HTML's "active parser was aborted" flag also makes open/write no-ops.
+_active_parser_aborted: bool = false,
 _current_script: ?*Element.Html.Script = null,
 _elements_by_id: std.StringHashMapUnmanaged(*Element) = .empty,
 // Track IDs that were removed from the map - they might have duplicates in the tree
@@ -996,6 +999,8 @@ fn writeInternal(self: *Document, text: []const []const u8, append_newline: bool
         return error.InvalidStateError;
     }
 
+    if (self._active_parser_aborted) return;
+
     const html = blk: {
         var joined: std.ArrayList(u8) = .empty;
         for (text) |str| {
@@ -1122,7 +1127,7 @@ pub fn open(self: *Document, call_frame: *Frame) !*Document {
         return error.InvalidStateError;
     }
 
-    if (frame._load_state == .parsing) {
+    if (self._active_parser_aborted or frame._load_state == .parsing) {
         return self;
     }
 
@@ -1148,6 +1153,9 @@ pub fn open(self: *Document, call_frame: *Frame) !*Document {
     self._style_sheets = null;
     self._implementation = null;
     self._ready_state = .loading;
+    // open() cancels an ongoing navigation; the aborted document's load is
+    // gone for good, as in Chrome.
+    frame.cancelQueuedNavigation();
 
     self._script_created_parser = Parser.Streaming.init(frame.arena, doc_node, frame, .{ .allow_declarative_shadow = true });
     try self._script_created_parser.?.start();