diff --git a/moli-renderer-v8/src/context_bootstrap/history_mutation.rs b/moli-renderer-v8/src/context_bootstrap/history_mutation.rs
index a56cae227a..e78ff9c29c 100644
--- a/moli-renderer-v8/src/context_bootstrap/history_mutation.rs
+++ b/moli-renderer-v8/src/context_bootstrap/history_mutation.rs
@@ -24,6 +24,7 @@ use super::navigation_result::{
 };
 use super::navigation_serialize::sync_child_navigation_entry_seed_from_owner;
 use super::navigation_window::{
+    child_browsing_context_handle_for_runtime_owner,
     runtime_window_is_global, window_location_for_holder, window_navigation_for_holder,
 };
 use super::*;
@@ -107,6 +108,7 @@ fn mutate_history_object<'s>(
     let Some(owner) = require_fully_active_history_owner(scope, history) else {
         return;
     };
+    let kind = effective_history_mutation_kind(scope, owner, kind);
     let Some(state) = structured_clone_value_for_storage(scope, parsed.state) else {
         return;
     };
@@ -116,9 +118,9 @@ fn mutate_history_object<'s>(
     };
     let current_href =
         location_href_slot(scope, location).unwrap_or_else(|| "about:blank".to_owned());
-    let current_url = match history_same_origin_reference_url(scope, owner, &current_href) {
-        Ok(url) => url,
-        Err(_) => {
+    let current_url = match history_document_url(scope, owner, &current_href) {
+        Some(url) => url,
+        None => {
             throw_history_security_error(
                 scope,
                 "Failed to execute 'pushState' or 'replaceState' on 'History': The current URL is invalid.",
@@ -126,13 +128,9 @@ fn mutate_history_object<'s>(
             return;
         }
     };
-    let resolve_base_href = if history_url_inherits_origin(scope, owner, &current_href) {
-        current_url.as_str()
-    } else {
-        &current_href
-    };
+    let api_base_url = history_api_base_url(scope, owner, &current_url);
     let url = match parsed.url {
-        Some(target) if !target.is_empty() => resolve_history_state_url(resolve_base_href, &target),
+        Some(target) if !target.is_empty() => resolve_history_state_url(&api_base_url, &target),
         _ => Some(current_url.clone()),
     };
     let Some(url) = url else {
@@ -142,7 +140,7 @@ fn mutate_history_object<'s>(
         );
         return;
     };
-    if !moli_url::same_origin(&url, &current_url) {
+    if !document_can_have_url_rewritten(&current_url, &url) {
         throw_history_security_error(
             scope,
             "Failed to execute 'pushState' or 'replaceState' on 'History': A history state object with URL of a different origin cannot be created in a document with origin.",
@@ -305,18 +303,16 @@ fn mutate_history_object<'s>(
     } else if let Some(popup_id) =
         crate::native_bridge::lightweight_popup_id_from_window(scope, owner)
         && let Some(host_ptr) = context_host_ptr_from_global_bridge(scope)
-        && let Some(document_handle) =
-            unsafe { &*host_ptr }.lightweight_popup_document_handle(popup_id)
     {
-        let _ = unsafe { &mut *host_ptr }.set_dom_document_url_for_handle(document_handle, url);
+        let _ = unsafe { &mut *host_ptr }.set_lightweight_popup_same_document_url(popup_id, url);
     }
 }
 
-fn resolve_history_state_url(base_href: &str, target: &str) -> Option<url::Url> {
+fn resolve_history_state_url(base_url: &url::Url, target: &str) -> Option<url::Url> {
     if let Ok(absolute) = url::Url::parse(target) {
         return Some(absolute);
     }
-    url::Url::parse(base_href).ok()?.join(target).ok()
+    base_url.join(target).ok()
 }
 
 fn parse_history_mutation_args<'s>(
@@ -344,28 +340,155 @@ fn parse_history_mutation_args<'s>(
     }
 }
 
-fn history_same_origin_reference_url<'s>(
+fn history_api_base_url<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     owner: v8::Local<'s, v8::Object>,
-    current_href: &str,
-) -> Result<url::Url, url::ParseError> {
-    if history_url_inherits_origin(scope, owner, current_href)
-        && let Some(host_ptr) = context_host_ptr_from_global_bridge(scope)
-    {
-        return Ok(unsafe { &mut *host_ptr }.host_document().url().clone());
+    current_url: &url::Url,
+) -> url::Url {
+    let Some(host_ptr) = context_host_ptr_from_global_bridge(scope) else {
+        return current_url.clone();
+    };
+    let host = unsafe { &*host_ptr };
+    if runtime_window_is_global(scope, owner) {
+        return host
+            .dom_host()
+            .document_base_url()
+            .unwrap_or_else(|| current_url.clone());
     }
-    url::Url::parse(current_href)
+    if let Some(handle) = child_browsing_context_handle_for_runtime_owner(scope, owner) {
+        return host
+            .child_browsing_context_base_url(handle)
+            .unwrap_or_else(|| current_url.clone());
+    }
+    if let Some(popup_id) = crate::native_bridge::lightweight_popup_id_from_window(scope, owner) {
+        return host
+            .lightweight_popup_request_base_url(scope, popup_id)
+            .unwrap_or_else(|| current_url.clone());
+    }
+    current_url.clone()
 }
 
-fn history_url_inherits_origin<'s>(
+fn history_document_url<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     owner: v8::Local<'s, v8::Object>,
     current_href: &str,
-) -> bool {
-    !runtime_window_is_global(scope, owner)
-        && matches!(current_href, "about:blank" | "about:srcdoc")
+) -> Option<url::Url> {
+    let Some(host_ptr) = context_host_ptr_from_global_bridge(scope) else {
+        return url::Url::parse(current_href).ok();
+    };
+    let host = unsafe { &*host_ptr };
+    if runtime_window_is_global(scope, owner) {
+        return Some(host.document_url().clone());
+    }
+    if let Some(handle) = child_browsing_context_handle_for_runtime_owner(scope, owner) {
+        return host.child_browsing_context_current_url(handle);
+    }
+    if let Some(popup_id) = crate::native_bridge::lightweight_popup_id_from_window(scope, owner) {
+        if host.lightweight_popup_current_document_is_initial_empty(popup_id) {
+            return url::Url::parse("about:blank").ok();
+        }
+        return host.lightweight_popup_document_url(popup_id);
+    }
+    url::Url::parse(current_href).ok()
+}
+
+fn effective_history_mutation_kind<'s>(
+    scope: &mut v8::PinScope<'s, '_>,
+    owner: v8::Local<'s, v8::Object>,
+    kind: HistoryMutationKind,
+) -> HistoryMutationKind {
+    if !matches!(kind, HistoryMutationKind::Push) {
+        return kind;
+    }
+    let Some(host_ptr) = context_host_ptr_from_global_bridge(scope) else {
+        return kind;
+    };
+    let host = unsafe { &*host_ptr };
+    let is_initial_empty = child_browsing_context_handle_for_runtime_owner(scope, owner)
+        .is_some_and(|handle| host.child_browsing_context_is_on_initial_about_blank_entry(handle))
+        || crate::native_bridge::lightweight_popup_id_from_window(scope, owner).is_some_and(
+            |popup_id| host.lightweight_popup_current_document_is_initial_empty(popup_id),
+        );
+    if is_initial_empty {
+        HistoryMutationKind::Replace
+    } else {
+        kind
+    }
+}
+
+fn document_can_have_url_rewritten(document_url: &url::Url, target_url: &url::Url) -> bool {
+    if document_url.scheme() != target_url.scheme()
+        || document_url.username() != target_url.username()
+        || document_url.password() != target_url.password()
+        || document_url.host() != target_url.host()
+        || document_url.port() != target_url.port()
+    {
+        return false;
+    }
+    if matches!(target_url.scheme(), "http" | "https") {
+        return true;
+    }
+    if target_url.scheme() == "file" {
+        return document_url.path() == target_url.path();
+    }
+    document_url.path() == target_url.path() && document_url.query() == target_url.query()
 }
 
 fn throw_history_security_error(scope: &mut v8::PinScope<'_, '_>, message: &str) {
     crate::context_bootstrap::throw_dom_exception_value(scope, message, "SecurityError");
 }
+
+#[cfg(test)]
+mod tests {
+    use super::document_can_have_url_rewritten;
+    use url::Url;
+
+    fn url(value: &str) -> Url {
+        Url::parse(value).expect("test URL should parse")
+    }
+
+    #[test]
+    fn history_url_rewrite_rules_match_url_component_boundaries() {
+        let cases = [
+            (
+                "https://example.test/home",
+                "https://example.test/shop",
+                true,
+            ),
+            (
+                "https://example.test/home",
+                "https://user:pass@example.test/home",
+                false,
+            ),
+            ("file:///path/to/x", "file:///path/to/x?search", true),
+            ("file:///path/to/x", "file:///path/to/y", false),
+            ("about:blank", "about:blank#hash", true),
+            ("about:blank", "about:blank?search", false),
+            ("about:blank", "about:srcdoc", false),
+            ("data:text/html,body", "data:text/html,body#hash", true),
+            ("data:text/html,body", "data:text/html,body?search", false),
+            (
+                "blob:https://example.test/00000000-0000-0000-0000-000000000001",
+                "blob:https://example.test/00000000-0000-0000-0000-000000000001#hash",
+                true,
+            ),
+            (
+                "blob:https://example.test/00000000-0000-0000-0000-000000000001",
+                "blob:https://example.test/00000000-0000-0000-0000-000000000001?search",
+                false,
+            ),
+            (
+                "blob:https://example.test/00000000-0000-0000-0000-000000000001",
+                "blob:https://example.test/00000000-0000-0000-0000-000000000002",
+                false,
+            ),
+        ];
+        for (document, target, expected) in cases {
+            assert_eq!(
+                document_can_have_url_rewritten(&url(document), &url(target)),
+                expected,
+                "rewrite result for {document} -> {target}"
+            );
+        }
+    }
+}
diff --git a/moli-renderer-v8/src/context_bootstrap/navigation_projection.rs b/moli-renderer-v8/src/context_bootstrap/navigation_projection.rs
index 592d934bca..842c918748 100644
--- a/moli-renderer-v8/src/context_bootstrap/navigation_projection.rs
+++ b/moli-renderer-v8/src/context_bootstrap/navigation_projection.rs
@@ -217,7 +217,8 @@ fn entry_origin_url<'s>(
 }
 
 fn child_navigation_entry_url_inherits_origin(url: &url::Url) -> bool {
-    url.scheme() == "about" && matches!(url.as_str(), "about:blank" | "about:srcdoc")
+    url.scheme() == "about"
+        && (url.path().eq_ignore_ascii_case("blank") || url.path().eq_ignore_ascii_case("srcdoc"))
 }
 
 pub(super) fn set_history_length_from_visible_entries<'s>(
@@ -278,3 +279,26 @@ fn history_length_floor_from_visible_entries<'s>(
         .max(0.0);
     visible_length.max(top_length)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::child_navigation_entry_url_inherits_origin;
+    use url::Url;
+
+    #[test]
+    fn about_document_history_urls_inherit_origin_with_fragments() {
+        for raw_url in [
+            "about:blank",
+            "about:blank#history",
+            "about:srcdoc",
+            "about:srcdoc#history",
+        ] {
+            assert!(child_navigation_entry_url_inherits_origin(
+                &Url::parse(raw_url).expect("about URL should parse")
+            ));
+        }
+        assert!(!child_navigation_entry_url_inherits_origin(
+            &Url::parse("about:other#history").expect("about URL should parse")
+        ));
+    }
+}
diff --git a/moli-renderer-v8/src/native_bridge/context_host/child_frames.rs b/moli-renderer-v8/src/native_bridge/context_host/child_frames.rs
index aec6b8c553..b68126a3d2 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/child_frames.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/child_frames.rs
@@ -728,8 +728,9 @@ impl ChildBrowsingContextEntry {
         self.navigation_entry_seed = entry_seed.clone();
         if same_document_update {
             self.committed_navigation_entry_seed = entry_seed;
-            self.pending_attribute_bootstrap_commit = false;
-            self.pending_live_navigation_reflects_window_state = false;
+            if !self.pending_attribute_bootstrap_commit {
+                self.pending_live_navigation_reflects_window_state = false;
+            }
         }
         same_document_update
     }
diff --git a/moli-renderer-v8/src/native_bridge/context_host/popups.rs b/moli-renderer-v8/src/native_bridge/context_host/popups.rs
index bef01d32e9..58ffc78224 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/popups.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/popups.rs
@@ -386,6 +386,7 @@ pub(super) struct LightweightPopupDocumentState {
 struct LightweightPopupDocumentRecord {
     owner: LightweightPopupDocumentOwner,
     local_window_id: LightweightPopupLocalWindowId,
+    is_initial_empty_document: bool,
     url: Url,
     access_origin: super::window_security_tokens::WindowAccessOrigin,
     state: LightweightPopupDocumentState,
@@ -685,15 +686,25 @@ impl JsContextHost {
         true
     }
 
-    fn set_lightweight_popup_same_document_url(&mut self, popup_id: u64, url: Url) -> bool {
-        let Some(record) = self.lightweight_popup_record_mut(popup_id) else {
-            return false;
+    pub(crate) fn set_lightweight_popup_same_document_url(
+        &mut self,
+        popup_id: u64,
+        url: Url,
+    ) -> bool {
+        let document_handle = {
+            let Some(record) = self.lightweight_popup_record_mut(popup_id) else {
+                return false;
+            };
+            let LightweightPopupLifecycle::Open(open) = &mut record.lifecycle else {
+                return false;
+            };
+            record.location_url = url.clone();
+            open.document.url = url.clone();
+            open.document.handle
         };
-        let LightweightPopupLifecycle::Open(open) = &mut record.lifecycle else {
-            return false;
-        };
-        record.location_url = url.clone();
-        open.document.url = url;
+        if let Some(document_handle) = document_handle {
+            let _ = self.set_dom_document_url_for_handle(document_handle, url);
+        }
         true
     }
 
@@ -933,6 +944,7 @@ impl JsContextHost {
                     document: LightweightPopupDocumentRecord {
                         owner: initial_document_owner,
                         local_window_id: initial_local_window_id,
+                        is_initial_empty_document: true,
                         url: initial_url.clone(),
                         access_origin: initial_origin,
                         state: initial_document_state.clone(),
@@ -1081,7 +1093,6 @@ impl JsContextHost {
             window,
             &target_url,
             crate::context_bootstrap::LocationNavigationKind::Assign,
-            Some(&previous_url),
         );
         let queue_synthetic_load = if moli_url::is_about_blank(&target_url) {
             let storage_scope = self.lightweight_popup_storage_scope_for_initiated_navigation(
@@ -1228,6 +1239,14 @@ impl JsContextHost {
             .map(|document| document.url.clone())
     }
 
+    pub(crate) fn lightweight_popup_current_document_is_initial_empty(
+        &self,
+        popup_id: u64,
+    ) -> bool {
+        self.lightweight_popup_document_record(popup_id)
+            .is_some_and(|document| document.is_initial_empty_document)
+    }
+
     pub(crate) fn lightweight_popup_session_storage_store(
         &self,
         popup_id: u64,
@@ -1495,9 +1514,7 @@ impl JsContextHost {
         window: v8::Local<'s, v8::Object>,
         target_url: &Url,
         kind: crate::context_bootstrap::LocationNavigationKind,
-        current_url: Option<&Url>,
     ) {
-        let effective_kind = lightweight_popup_effective_navigation_kind(current_url, kind);
         let base_url = self
             .lightweight_popup_base_url(scope, popup_id)
             .unwrap_or_else(|| target_url.clone());
@@ -1512,7 +1529,7 @@ impl JsContextHost {
             &base_url,
             &document_referrer,
         );
-        apply_local_window_location_navigation(scope, window, target_url, effective_kind);
+        apply_local_window_location_navigation(scope, window, target_url, kind);
         sync_window_location_history_navigation_runtime_surface(scope, window);
     }
 
@@ -1566,6 +1583,10 @@ impl JsContextHost {
         let Some(window) = self.lightweight_popup_window(scope, popup_id) else {
             return false;
         };
+        let kind = lightweight_popup_effective_navigation_kind(
+            self.lightweight_popup_current_document_is_initial_empty(popup_id),
+            kind,
+        );
         let current_url = lightweight_popup_location_href(scope, window)
             .or_else(|| self.lightweight_popup_location_url(popup_id));
         if !matches!(
@@ -1696,7 +1717,6 @@ impl JsContextHost {
                 window,
                 &target_url,
                 kind,
-                current_url.as_ref(),
             );
             self.install_lightweight_popup_empty_document(scope, popup_id, window, target_url);
             self.queue_lightweight_popup_load_event(navigation_task);
@@ -1709,7 +1729,6 @@ impl JsContextHost {
             window,
             &target_url,
             kind,
-            current_url.as_ref(),
         );
         if self
             .start_lightweight_popup_document_load(
@@ -1951,6 +1970,7 @@ impl JsContextHost {
                 LightweightPopupDocumentRecord {
                     owner: commit.owner,
                     local_window_id: current_local_window_id,
+                    is_initial_empty_document: false,
                     url: commit.location_url.clone(),
                     access_origin,
                     state: commit.state,
@@ -4926,13 +4946,13 @@ fn set_lightweight_popup_persisted_script_global<'s>(
 }
 
 fn lightweight_popup_effective_navigation_kind(
-    current_url: Option<&Url>,
+    current_document_is_initial_empty: bool,
     kind: crate::context_bootstrap::LocationNavigationKind,
 ) -> crate::context_bootstrap::LocationNavigationKind {
     if matches!(
         kind,
         crate::context_bootstrap::LocationNavigationKind::Assign
-    ) && current_url.is_some_and(moli_url::is_about_blank)
+    ) && current_document_is_initial_empty
     {
         return crate::context_bootstrap::LocationNavigationKind::Replace;
     }
diff --git a/moli-renderer-v8/src/runtime/page_vm/tests/hash_change_delivery.rs b/moli-renderer-v8/src/runtime/page_vm/tests/hash_change_delivery.rs
index a4d60059d5..6d0e2cfeb5 100644
--- a/moli-renderer-v8/src/runtime/page_vm/tests/hash_change_delivery.rs
+++ b/moli-renderer-v8/src/runtime/page_vm/tests/hash_change_delivery.rs
@@ -398,10 +398,17 @@ async fn hashchange_discards_a_retired_child_local_window() {
             r#"
 const frame = document.createElement("iframe");
 frame.id = "stale-hashchange-recipient";
+frame.srcdoc = "<!doctype html><p>child</p>";
 document.body.appendChild(frame);
 "created"
 "#,
         )?;
+        run_expected_child_frame_task_source_after_realm_prerequisite_for_wait(
+            &mut page_vm,
+            ChildFrameSemanticTurnKind::NavigationCommit,
+            "stale hashchange child srcdoc commit",
+        )
+        .await;
         materialize_child_realm_through_page_turn_for_test(
             &mut page_vm,
             "stale-hashchange-recipient",
@@ -411,7 +418,7 @@ document.body.appendChild(frame);
 globalThis.__staleHashChanges = 0;
 const staleFrame = document.getElementById("stale-hashchange-recipient");
 staleFrame.contentWindow.addEventListener("hashchange", () => parent.__staleHashChanges++);
-staleFrame.contentWindow.history.replaceState(null, "", "/child-hashchange");
+staleFrame.contentWindow.history.replaceState(null, "", "about:srcdoc#child-hashchange");
 staleFrame.contentWindow.location.hash = "#queued";
 staleFrame.remove();
 "retired"
@@ -447,7 +454,7 @@ async fn hashchange_discards_a_retired_lightweight_popup_local_window() {
             r##"
 globalThis.__popupHashChanges = [];
 globalThis.__hashPopup = open("about:blank", "hashchange-owner-popup");
-__hashPopup.history.replaceState(null, "", "/popup-hashchange");
+__hashPopup.history.replaceState(null, "", "about:blank#popup-hashchange");
 __hashPopup.addEventListener("hashchange", () => __popupHashChanges.push("retired"));
 __hashPopup.location.hash = "#queued-before-replacement";
 open("about:blank", "hashchange-owner-popup");
@@ -479,7 +486,7 @@ open("about:blank", "hashchange-owner-popup");
 
         page_vm.vm_mut().eval(
             r##"
-__hashPopup.history.replaceState(null, "", "/replacement-popup-hashchange");
+__hashPopup.history.replaceState(null, "", "about:blank#replacement-popup-hashchange");
 __hashPopup.addEventListener("hashchange", () => __popupHashChanges.push("current"));
 __hashPopup.location.hash = "#queued-after-replacement";
 "queued-current"
diff --git a/moli-renderer-v8/src/runtime/page_vm/tests/history_traversal.rs b/moli-renderer-v8/src/runtime/page_vm/tests/history_traversal.rs
index f3f4653968..2cf40d4dd8 100644
--- a/moli-renderer-v8/src/runtime/page_vm/tests/history_traversal.rs
+++ b/moli-renderer-v8/src/runtime/page_vm/tests/history_traversal.rs
@@ -313,10 +313,17 @@ async fn history_traversal_discards_a_retired_child_local_window() {
             r##"
 const frame = document.createElement("iframe");
 frame.id = "history-stale-child";
+frame.srcdoc = "<!doctype html><p>child</p>";
 document.body.appendChild(frame);
 "created"
 "##,
         )?;
+        run_expected_child_frame_task_source_after_realm_prerequisite_for_wait(
+            &mut page_vm,
+            ChildFrameSemanticTurnKind::NavigationCommit,
+            "history stale-child srcdoc commit",
+        )
+        .await;
         materialize_child_realm_through_page_turn_for_test(&mut page_vm, "history-stale-child")?;
         page_vm.vm_mut().eval(
             r##"
@@ -325,7 +332,7 @@ const child = document.getElementById("history-stale-child").contentWindow;
 child.addEventListener("popstate", () => {
   parent.__retiredChildHistoryEvents += 1;
 });
-child.history.pushState(null, "", "#queued");
+child.history.pushState(null, "", "about:srcdoc#queued");
 child.history.back();
 document.getElementById("history-stale-child").remove();
 "retired"
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/misc.rs b/moli-renderer-v8/src/script_vm/tests/browser_api/misc.rs
index cb50d538d1..3473a49a63 100644
--- a/moli-renderer-v8/src/script_vm/tests/browser_api/misc.rs
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/misc.rs
@@ -26279,6 +26279,39 @@ JSON.stringify({
     );
 }
 
+#[test]
+fn window_open_named_reuse_before_first_commit_pushes_history() {
+    let mut vm = new_storage_test_vm("https://example.com/base/page.html");
+
+    assert_eq!(
+        vm.eval(
+            r#"
+(() => {
+  const firstUrl = URL.createObjectURL(
+    new Blob(['<!doctype html><p>first</p>'], { type: 'text/html' })
+  );
+  const secondUrl = URL.createObjectURL(
+    new Blob(['<!doctype html><p>second</p>'], { type: 'text/html' })
+  );
+  const popup = open(firstUrl, 'pendingNamedPopup');
+  const reopened = open(secondUrl, 'pendingNamedPopup');
+  const result = [
+    popup === reopened,
+    reopened.location.href === secondUrl,
+    reopened.history.length,
+  ].join('|');
+  popup.close();
+  URL.revokeObjectURL(firstUrl);
+  URL.revokeObjectURL(secondUrl);
+  return result;
+})()
+"#,
+        )
+        .expect("pending named popup reuse should evaluate"),
+        "true|true|2"
+    );
+}
+
 #[tokio::test]
 async fn lightweight_popup_cross_document_navigation_clears_old_onload_handler() {
     let loader = ResourceRequestClient::new(&moli_fetch::FetchConfig::default()).expect("loader");
@@ -27580,6 +27613,32 @@ async fn window_open_204_popup_ignores_navigation_and_preserves_initial_empty_hi
     );
 }
 
+#[test]
+fn window_open_initial_empty_history_push_is_a_replacement() {
+    let mut vm = new_storage_test_vm("https://initial-popup-history.test/page.html");
+
+    assert_eq!(
+        vm.eval(
+            r#"
+(() => {
+  const popup = open();
+  popup.history.pushState({ step: 1 }, '', 'about:blank#pushed');
+  popup.history.replaceState({ step: 2 }, '', 'about:blank#replaced');
+  const result = [
+    popup.location.href,
+    popup.history.state.step,
+    popup.history.length,
+  ].join('|');
+  popup.close();
+  return result;
+})()
+"#,
+        )
+        .expect("initial empty popup history mutation should evaluate"),
+        "about:blank#replaced|2|1"
+    );
+}
+
 #[tokio::test]
 async fn window_open_without_url_replaces_initial_empty_history_on_first_navigation() {
     let (origin, server) = spawn_lightweight_popup_relative_navigation_server().await;
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/navigation.rs b/moli-renderer-v8/src/script_vm/tests/browser_api/navigation.rs
index 98304d0027..1070d953b3 100644
--- a/moli-renderer-v8/src/script_vm/tests/browser_api/navigation.rs
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/navigation.rs
@@ -4192,7 +4192,7 @@ async fn reset_navigation_history_updates_all_live_window_realms() {
         .clone();
     vm.eval_in_child_default_context(
         child_context_id,
-        r##"history.pushState({ realm: "child-default" }, "", "#child-default")"##,
+        r##"history.pushState({ realm: "child-default" }, "", "about:srcdoc#child-default")"##,
     )
     .expect("child default history setup should evaluate");
 
@@ -4209,7 +4209,7 @@ async fn reset_navigation_history_updates_all_live_window_realms() {
     .expect("top isolated history setup should evaluate");
     vm.eval_in_isolated_context(
         child_isolated_context_id,
-        r##"history.pushState({ realm: "child-isolated" }, "", "#child-isolated")"##,
+        r##"history.pushState({ realm: "child-isolated" }, "", "about:srcdoc#child-isolated")"##,
     )
     .expect("child isolated history setup should evaluate");
 
@@ -4347,7 +4347,11 @@ async fn reset_navigation_history_preserves_child_entry_created_by_top_dispose_l
         child_context_id,
         r##"
 (() => {
-  history.pushState({ realm: "child-before-reset" }, "", "#child-before-reset");
+  history.pushState(
+    { realm: "child-before-reset" },
+    "",
+    "about:srcdoc#child-before-reset"
+  );
   globalThis.__lmChildCurrentBeforeReset = navigation.currentEntry;
   globalThis.__lmChildEntriesBeforeReset = navigation.entries();
   globalThis.__lmChildDisposed = [];
@@ -4364,7 +4368,7 @@ navigation.entries()[0].addEventListener("dispose", () => {
   document.querySelector("iframe").contentWindow.history.pushState(
     { realm: "child-during-top-dispose" },
     "",
-    "#child-during-top-dispose"
+    "about:srcdoc#child-during-top-dispose"
   );
 });
 "##,
diff --git a/moli-renderer-v8/src/script_vm/tests/dom_elements/dom_surface.rs b/moli-renderer-v8/src/script_vm/tests/dom_elements/dom_surface.rs
index 87523954c5..acac8ff631 100644
--- a/moli-renderer-v8/src/script_vm/tests/dom_elements/dom_surface.rs
+++ b/moli-renderer-v8/src/script_vm/tests/dom_elements/dom_surface.rs
@@ -6709,7 +6709,7 @@ async fn element_matches_delegates_loaded_child_document_elements() {
             r##"
 (() => {
   const doc = document.querySelector("iframe").contentDocument;
-  doc.defaultView.history.replaceState(null, "", "#target");
+  doc.defaultView.history.replaceState(null, "", "about:srcdoc#target");
   const code = doc.getElementById("code");
   return [
     code.ownerDocument === doc,
@@ -11000,9 +11000,9 @@ const frame = document.createElement('iframe');
 frame.name = 'target';
 const root = document.body || document.documentElement || document;
 root.appendChild(frame);
-frame.contentWindow.history.pushState(null, '', '/child.html');
+frame.contentWindow.history.replaceState(null, '', 'about:blank#child');
 const link = document.createElement('a');
-link.href = '/child.html#next';
+link.href = 'about:blank#next';
 link.target = 'target';
 root.appendChild(link);
 let seen = [];
@@ -11020,10 +11020,7 @@ seen.join('|')
         )
         .expect("targeted same-document anchor click should dispatch child navigate");
 
-    assert_eq!(
-        result,
-        "true,true,https://targeted-child-hash.test/child.html#next,-1"
-    );
+    assert_eq!(result, "true,true,about:blank#next,-1");
 }
 #[test]
 fn anchor_click_to_identical_url_dispatches_replace_navigate_event() {
@@ -11933,7 +11930,7 @@ globalThis.__firstJointLengthFrame = first;
 (() => {
   const child = __firstJointLengthFrame.contentWindow;
   const before = history.length;
-  child.history.pushState(null, '', '#first');
+  child.history.pushState(null, '', 'about:srcdoc#first');
   return [before, history.length, child.history.length].join('|');
 })()
 "#,
@@ -11960,7 +11957,7 @@ globalThis.__secondJointLengthFrame = second;
 (() => {
   const child = __secondJointLengthFrame.contentWindow;
   const before = history.length;
-  child.history.pushState(null, '', '#second');
+  child.history.pushState(null, '', 'about:srcdoc#second');
   return [before, history.length, child.history.length].join('|');
 })()
 "#,
@@ -11970,6 +11967,65 @@ globalThis.__secondJointLengthFrame = second;
     );
 }
 
+#[test]
+fn initial_empty_child_history_can_rewrite_about_blank_fragment() {
+    let mut vm = new_storage_test_vm("https://initial-empty-history.test/page.html");
+
+    assert_eq!(
+        vm.eval(
+            r#"
+(() => {
+  const frame = document.createElement('iframe');
+  (document.body || document.documentElement || document).appendChild(frame);
+  const child = frame.contentWindow;
+  const before = history.length;
+  child.history.pushState({ step: 1 }, '', 'about:blank#pushed');
+  child.history.replaceState({ step: 2 }, '', 'about:blank#replaced');
+  return [
+    child.location.href,
+    child.history.state.step,
+    history.length,
+    before,
+  ].join('|');
+})()
+"#,
+        )
+        .expect("initial empty child history mutation should evaluate"),
+        "about:blank#replaced|2|1|1"
+    );
+}
+
+#[test]
+fn initial_empty_child_history_mutation_preserves_pending_srcdoc_navigation() {
+    let mut vm = new_storage_test_vm("https://pending-child-history.test/page.html");
+
+    assert_eq!(
+        vm.eval(
+            r#"
+(() => {
+  const frame = document.createElement('iframe');
+  frame.srcdoc = '<p id="committed">child</p>';
+  (document.body || document.documentElement || document).appendChild(frame);
+  frame.contentWindow.history.pushState(null, '', 'about:blank#before-commit');
+  globalThis.__pendingHistoryFrame = frame;
+  return frame.contentWindow.location.href;
+})()
+"#,
+        )
+        .expect("pending child history mutation should evaluate"),
+        "about:blank#before-commit"
+    );
+
+    vm.drain_pending_child_frame_work_for_test();
+    assert_eq!(
+        vm.eval(
+            "[__pendingHistoryFrame.contentWindow.location.href, Boolean(__pendingHistoryFrame.contentDocument.getElementById('committed'))].join('|')"
+        )
+        .expect("pending srcdoc navigation should still commit"),
+        "about:srcdoc|true"
+    );
+}
+
 #[tokio::test]
 async fn top_history_back_routes_to_child_joint_history_entry() {
     let loader = ResourceRequestClient::new(&moli_fetch::FetchConfig::default()).expect("loader");
@@ -12004,7 +12060,11 @@ async fn top_history_back_routes_to_child_joint_history_entry() {
             r#"
 (() => {
   const frame = document.querySelector('iframe');
-  frame.contentWindow.history.pushState({ child: true }, '', '#child');
+  frame.contentWindow.history.pushState(
+    { child: true },
+    '',
+    'about:srcdoc#child'
+  );
   return [
     location.href,
     history.length,
@@ -12018,7 +12078,7 @@ async fn top_history_back_routes_to_child_joint_history_entry() {
 
     assert_eq!(
         setup,
-        "https://joint-child-back.test/page.html|2|2|https://joint-child-back.test/page.html#child"
+        "https://joint-child-back.test/page.html|2|2|about:srcdoc#child"
     );
     let _ = vm
         .run_one_oldest_ready_page_task_executor_turn(&loader)
@@ -12084,7 +12144,11 @@ async fn top_history_back_ignores_removed_child_joint_history_entry() {
             r#"
 (() => {
   const frame = document.querySelector('iframe');
-  frame.contentWindow.history.pushState({ child: true }, '', '#child');
+  frame.contentWindow.history.pushState(
+    { child: true },
+    '',
+    'about:srcdoc#child'
+  );
   return [
     location.href,
     navigation.entries().length,
@@ -12100,7 +12164,7 @@ async fn top_history_back_ignores_removed_child_joint_history_entry() {
 
     assert_eq!(
         setup,
-        "https://removed-child-joint-back.test/page.html|1|0|2|2|https://removed-child-joint-back.test/page.html#child"
+        "https://removed-child-joint-back.test/page.html|1|0|2|2|about:srcdoc#child"
     );
 
     vm.eval("document.querySelector('iframe').remove(); history.back(); 'queued'")
@@ -12208,7 +12272,7 @@ async fn detached_child_navigation_error_exposes_committed_entry_during_dispatch
 (() => {
   globalThis.__lmDetachedChildNavigateErrorLog = [];
   const child = document.querySelector('iframe').contentWindow;
-  child.history.pushState({ child: true }, "", "#one");
+  child.history.pushState({ child: true }, "", "about:srcdoc#one");
   return [
     child.navigation.entries().length,
     child.navigation.currentEntry.index,
@@ -12218,10 +12282,7 @@ async fn detached_child_navigation_error_exposes_committed_entry_during_dispatch
 "##,
         )
         .expect("child initial same-document navigation should evaluate");
-    assert_eq!(
-        initial,
-        "2|1|https://child-detach-navigation-error.test/page.html#one"
-    );
+    assert_eq!(initial, "2|1|about:srcdoc#one");
 
     let setup = vm
         .eval(
diff --git a/moli-renderer-v8/src/script_vm/tests/dom_xhr/computed_style.rs b/moli-renderer-v8/src/script_vm/tests/dom_xhr/computed_style.rs
index e22d2d37e0..40f96fca54 100644
--- a/moli-renderer-v8/src/script_vm/tests/dom_xhr/computed_style.rs
+++ b/moli-renderer-v8/src/script_vm/tests/dom_xhr/computed_style.rs
@@ -9823,7 +9823,7 @@ fn child_frame_target_selector_invalidation_uses_child_document_world() {
     </body>
   `);
   childDocument.close();
-  childWindow.history.replaceState(null, '', '#old');
+  childWindow.history.replaceState(null, '', 'about:blank#old');
   globalThis.__childTargetFrame = frame;
   globalThis.__childTargetOldStyle =
     childWindow.getComputedStyle(childDocument.getElementById('old'));
@@ -9855,7 +9855,7 @@ fn child_frame_target_selector_invalidation_uses_child_document_world() {
             r#"
 (() => {
   const childWindow = globalThis.__childTargetFrame.contentWindow;
-  childWindow.history.replaceState(null, '', '#new');
+  childWindow.history.replaceState(null, '', 'about:blank#new');
   const result = [
     globalThis.__childTargetOldStyle.color,
     globalThis.__childTargetNewStyle.color
@@ -9923,7 +9923,7 @@ fn popup_target_selector_invalidation_uses_popup_document_world() {
   newTarget.id = 'popup-new-target';
   newTarget.className = 'probe';
   popupBody.append(oldTarget, newTarget);
-  popup.history.replaceState(null, '', '#popup-old-target');
+  popup.history.replaceState(null, '', 'about:blank#popup-old-target');
   globalThis.__popupTargetOldStyle = popup.getComputedStyle(oldTarget);
   globalThis.__popupTargetNewStyle = popup.getComputedStyle(newTarget);
 
@@ -9952,7 +9952,7 @@ fn popup_target_selector_invalidation_uses_popup_document_world() {
         .eval(
             r#"
 (() => {
-  __popupTargetWindow.history.replaceState(null, '', '#popup-new-target');
+  __popupTargetWindow.history.replaceState(null, '', 'about:blank#popup-new-target');
   const result = [
     globalThis.__popupTargetOldStyle.color,
     globalThis.__popupTargetNewStyle.color
diff --git a/moli-renderer-v8/src/script_vm/tests/dom_xhr/dom.rs b/moli-renderer-v8/src/script_vm/tests/dom_xhr/dom.rs
index a885977e25..7b1f468247 100644
--- a/moli-renderer-v8/src/script_vm/tests/dom_xhr/dom.rs
+++ b/moli-renderer-v8/src/script_vm/tests/dom_xhr/dom.rs
@@ -9614,7 +9614,7 @@ fn dom_parser_uses_its_constructor_realm_associated_document() {
   const frame = document.createElement('iframe');
   (document.body || document.documentElement || document).appendChild(frame);
   const child = frame.contentWindow;
-  child.history.replaceState(null, '', '/child-v1.html');
+  child.history.replaceState(null, '', 'about:blank#child-v1');
 
   const topParser = new DOMParser();
   const childParser = new child.DOMParser();
@@ -9635,7 +9635,7 @@ fn dom_parser_uses_its_constructor_realm_associated_document() {
       'text/html'
     ).URL;
   const beforeSameDocumentUpdate = parseUrl(childParser);
-  child.history.replaceState(null, '', '/child-v2.html');
+  child.history.replaceState(null, '', 'about:blank#child-v2');
 
   let invalidReceiver;
   try {
@@ -9664,7 +9664,7 @@ fn dom_parser_uses_its_constructor_realm_associated_document() {
 
     assert_eq!(
         result,
-        r#"{"top":"https://dom-parser-realm.test/top.html","child":"https://dom-parser-realm.test/child-v2.html","childWithTopNewTarget":"https://dom-parser-realm.test/child-v2.html","topWithChildNewTarget":"https://dom-parser-realm.test/top.html","beforeSameDocumentUpdate":"https://dom-parser-realm.test/child-v1.html","invalidReceiver":"TypeError"}"#
+        r#"{"top":"https://dom-parser-realm.test/top.html","child":"about:blank#child-v2","childWithTopNewTarget":"about:blank#child-v2","topWithChildNewTarget":"https://dom-parser-realm.test/top.html","beforeSameDocumentUpdate":"about:blank#child-v1","invalidReceiver":"TypeError"}"#
     );
 }
 
@@ -9679,7 +9679,7 @@ fn dom_parser_non_object_new_target_prototype_uses_new_target_realm_default() {
   const frame = document.createElement('iframe');
   (document.body || document.documentElement || document).appendChild(frame);
   const child = frame.contentWindow;
-  child.history.replaceState(null, '', '/child.html');
+  child.history.replaceState(null, '', 'about:blank#child');
 
   const TopBad = new Function();
   TopBad.prototype = 7;