Devices may publish to their own out ports' messages (a level set on the device itself)

backend/fluksio/api/deps.py

@@ -139,15 +139,19 @@ def _device_writable(device: DeviceDef, request: Request) -> set[str]:
     one is what entitles the screen to it. Reads are untouched — read-only is
     not blind, and a locked dashboard has to keep drawing live data.
 
-    The device's own ``in`` ports, as flows wire them, are added outside the
-    lock: it covers the controls on a dashboard, not the sensors on the
-    device. Its ``out`` ports are read, not written, unless a widget targets
-    them too.
+    The device's own ports, as flows wire them, are added outside the lock:
+    it covers the controls on a dashboard, not the device itself. Its ``in``
+    ports are its sensors; its ``out`` ports it publishes when set on the
+    device (a panel's brightness on its config page), so what follows the
+    message hears of it.
     """
     store: DashboardStore | None = getattr(request.app.state, "dashboard_store", None)
     if store is None:
         return set()
-    writable = _device_in(device, request)
+    owned: DeviceStore | None = getattr(request.app.state, "device_store", None)
+    writable = (
+        {b.message for b in owned.bound(device.id)} if owned is not None else set()
+    )
     defns = devices.dashboards_for(device, store)
     bound = sorted(
         {s.message for d in defns if (s := d.settings.get("locked")) and s.message}

backend/tests/api/routes/test_devices.py

@@ -639,10 +639,11 @@ def test_a_devices_own_ports_publish_through_a_lock(
 ) -> None:
     """An ``in`` port is the device's own sensor, which a dashboard lock is not about.
 
-    An ``out`` port is the device following a message, so it reads and does
-    not write, and only an ``in`` port's name opens the artifact upload. A
-    value published on a bound port is the device node's, whatever the device
-    says it is from.
+    An ``out`` port is the device following a message, which it publishes too
+    when set on the device itself (a panel's brightness on its config page).
+    Only an ``in`` port's name opens the artifact upload. A value published on
+    a bound ``in`` port is the device node's, whatever the device says it is
+    from.
     """
     _dashboard_with(client, superuser_token_headers, "panel_io_locked", PANEL_WIDGETS)
     _publish_settings(
@@ -690,7 +691,7 @@ def test_a_devices_own_ports_publish_through_a_lock(
         client.post(
             f"{messages}/porch.backlight", headers=panel_headers, json={"value": 50}
         ).status_code
-        == 403
+        == 200
     )
     assert (
         client.get(

docs/interface/dashboards.md

@@ -550,7 +550,9 @@ The credential may publish to its `in` messages even when a dashboard is
 locked, and may upload an artifact named after one
 (`PUT /artifacts?name=<message>`), which is how a microphone sends a recording.
 A value it publishes there is credited to its device node, so the node's edge
-lights up on the canvas. `out` messages are read only. The node is shown
+lights up on the canvas. It may publish to its `out` messages as well, for a
+level set on the device itself (a panel's brightness on its config page), so
+what follows the message hears of it; no upload there. The node is shown
 degraded, *Offline*, in amber while the device is not connected: a warning on
 Home, not a fault, since a panel switched off or asleep breaks nothing.