diff --git a/sandbox/hass_client/hass_client/approved_domains.py b/sandbox/hass_client/hass_client/approved_domains.py
index 6d480dc42131..ddd01c1fcd7c 100644
--- a/sandbox/hass_client/hass_client/approved_domains.py
+++ b/sandbox/hass_client/hass_client/approved_domains.py
@@ -26,11 +26,14 @@ Domain comparison is case-insensitive; everything is normalised to
 lowercase at insertion time so the lookups stay cheap.
 """
 
-from collections.abc import Iterable
+from collections.abc import Callable, Iterable
+import contextlib
 import logging
 
 _LOGGER = logging.getLogger(__name__)
 
+ApproveListener = Callable[[str], None]
+
 
 class ApprovedDomains:
     """Mutable set of domains the sandbox runtime is allowed to own."""
@@ -38,14 +41,38 @@ class ApprovedDomains:
     def __init__(self, initial: Iterable[str] | None = None) -> None:
         """Initialise the gate, optionally seeded with a starter set."""
         self._counts: dict[str, int] = {}
+        self._listeners: list[ApproveListener] = []
         if initial is not None:
             for domain in initial:
                 self.add(domain)
 
+    def add_listener(self, listener: ApproveListener) -> None:
+        """Subscribe ``listener`` to absent→present domain transitions.
+
+        The listener fires (with the lowercased domain) only the first time
+        a domain becomes approved, not on every refcount bump. Used by the
+        :class:`~hass_client.service_mirror.ServiceMirror` to replay services
+        a domain registered before its approval landed.
+        """
+        self._listeners.append(listener)
+
+    def remove_listener(self, listener: ApproveListener) -> None:
+        """Drop a previously-added approve listener (no-op if absent)."""
+        with contextlib.suppress(ValueError):
+            self._listeners.remove(listener)
+
     def add(self, domain: str) -> None:
-        """Approve ``domain``; multiple ``add`` calls bump a refcount."""
+        """Approve ``domain``; multiple ``add`` calls bump a refcount.
+
+        The first ``add`` for a domain (absent→present) notifies any
+        registered approve listeners.
+        """
         key = domain.lower()
+        is_new = key not in self._counts
         self._counts[key] = self._counts.get(key, 0) + 1
+        if is_new:
+            for listener in self._listeners:
+                listener(key)
 
     def remove(self, domain: str) -> None:
         """Drop one ``add`` for ``domain``; harmless when over-removed."""
diff --git a/sandbox/hass_client/hass_client/service_mirror.py b/sandbox/hass_client/hass_client/service_mirror.py
index 52fe169cb981..f191f63862aa 100644
--- a/sandbox/hass_client/hass_client/service_mirror.py
+++ b/sandbox/hass_client/hass_client/service_mirror.py
@@ -64,9 +64,16 @@ class ServiceMirror:
         self._unsub_removed = self.hass.bus.async_listen(
             EVENT_SERVICE_REMOVED, self._on_service_removed
         )
+        # Replay services a domain registered *before* it became approved:
+        # EVENT_SERVICE_REGISTERED fires synchronously during
+        # ``async_setup_entry``, but the entry runner only approves the
+        # domain once setup returns, so those early registrations were
+        # dropped. Re-mirror them the moment the domain is approved.
+        self.approved.add_listener(self.async_sync_domain)
 
     async def async_stop(self) -> None:
         """Detach the bus listeners."""
+        self.approved.remove_listener(self.async_sync_domain)
         if self._unsub_registered is not None:
             self._unsub_registered()
             self._unsub_registered = None
@@ -74,6 +81,21 @@ class ServiceMirror:
             self._unsub_removed()
             self._unsub_removed = None
 
+    @callback
+    def async_sync_domain(self, domain: str) -> None:
+        """Mirror every already-registered service of a freshly-approved domain.
+
+        Invoked as an :class:`ApprovedDomains` approve listener. Services
+        already mirrored (``_mirrored``) are skipped, so this is a no-op for
+        a domain that was approved before its services registered.
+        """
+        if self._channel is None or self._channel.closed:
+            return
+        if not self.approved.approves(domain):
+            return
+        for service in self.hass.services.async_services_for_domain(domain):
+            self._mirror_service(domain, service)
+
     @callback
     def _on_service_registered(self, event: Event) -> None:
         if self._channel is None or self._channel.closed:
@@ -89,6 +111,15 @@ class ServiceMirror:
                 sorted(self.approved.domains),
             )
             return
+        self._mirror_service(domain, service)
+
+    @callback
+    def _mirror_service(self, domain: str, service: str) -> None:
+        """Push one ``register_service`` for ``domain.service`` (once).
+
+        Shared by the live ``EVENT_SERVICE_REGISTERED`` path and the
+        approval-replay path. Caller guarantees the domain is approved.
+        """
         key = (domain.lower(), service.lower())
         if key in self._mirrored:
             return
diff --git a/sandbox/hass_client/tests/test_service_mirror.py b/sandbox/hass_client/tests/test_service_mirror.py
index 1b56050ba8da..633ee7845695 100644
--- a/sandbox/hass_client/tests/test_service_mirror.py
+++ b/sandbox/hass_client/tests/test_service_mirror.py
@@ -153,6 +153,60 @@ async def test_unapproved_domain_is_rejected(
     await mirror.async_stop()
 
 
+async def test_service_registered_before_approval_is_replayed(
+    channels: tuple[Channel, Channel], hass_runtime: Any
+) -> None:
+    """A service registered before its domain is approved is replayed on approval.
+
+    Mirrors the real race: ``EVENT_SERVICE_REGISTERED`` fires synchronously
+    while a service is registered inside ``async_setup_entry``, before the
+    entry runner approves the domain. The early registration is dropped at
+    fire time, then replayed the moment ``ApprovedDomains.add`` approves it.
+    """
+    main, sandbox = channels
+    register_calls: list[pb.RegisterService] = []
+
+    async def _on_register(msg: pb.RegisterService) -> pb.RegisterServiceResult:
+        register_calls.append(msg)
+        return pb.RegisterServiceResult(ok=True, installed=True)
+
+    main.register("sandbox/register_service", _on_register)
+    main.start()
+    sandbox.start()
+
+    # Start with an empty gate — the domain is NOT yet approved.
+    approved = ApprovedDomains()
+    mirror = ServiceMirror(hass_runtime, approved)
+    mirror.register(sandbox)
+
+    async def _svc(_call: Any) -> None:
+        return None
+
+    # Service registers while the domain is still unapproved (the setup race).
+    hass_runtime.services.async_register(
+        "phase1_demo",
+        "do_thing",
+        _svc,
+        supports_response=SupportsResponse.NONE,
+    )
+    # Give the (dropped) registration a few ticks; nothing should reach main.
+    for _ in range(20):
+        await asyncio.sleep(0)
+    assert register_calls == []
+
+    # Domain becomes approved — exactly what the entry runner does after
+    # ``async_setup`` returns — and the dropped service is now replayed.
+    approved.add("phase1_demo")
+
+    await _wait_until(lambda: bool(register_calls))
+
+    assert len(register_calls) == 1
+    assert register_calls[0].domain == "phase1_demo"
+    assert register_calls[0].service == "do_thing"
+
+    await mirror.async_stop()
+
+
 async def test_unregister_service_propagates(
     channels: tuple[Channel, Channel], hass_runtime: Any
 ) -> None: