fix(config): default display_levels to device preset, not global constant

The display_settings options step fell back to the global
DEFAULT_DISPLAY_LEVELS (16) when no value was stored yet, ignoring
the device's own preset (e.g. reterminal_e1002 supports 256 levels,
trmnl_og only 2). Resolve the preset first and use its
display_levels as the fallback default so a fresh entry pre-selects
a value the device can actually reproduce.

Author: cryptomilk

custom_components/eink_dashboard/config_flow.py

@@ -1058,7 +1058,12 @@ async def async_step_display_settings(
         """Update refresh interval, optimize, and image quality settings."""
         opts = self.config_entry.options
         optimize = opts.get("optimize", DEFAULT_OPTIMIZE)
-        display_levels = opts.get("display_levels", DEFAULT_DISPLAY_LEVELS)
+        device_model = opts.get("device_model", "")
+        preset = DEVICE_PRESETS.get(device_model)
+        default_display_levels = (
+            preset.display_levels if preset else DEFAULT_DISPLAY_LEVELS
+        )
+        display_levels = opts.get("display_levels", default_display_levels)
         schema_fields: dict = {
             vol.Required(
                 "update_interval",
@@ -1087,8 +1092,6 @@ async def async_step_display_settings(
             return self.async_create_entry(
                 data={**opts, **validated, **section},
             )
-        device_model = opts.get("device_model", "")
-        preset = DEVICE_PRESETS.get(device_model)
         if preset and preset.integration_dithers:
             optimize_note = (
                 "This device's Home Assistant integration handles image"

tests/test_config_flow.py

@@ -873,6 +873,52 @@ async def test_display_settings_has_top_level_display_levels(
         }
         assert "display_levels" in field_names
 
+    async def test_display_settings_defaults_to_device_preset_levels(
+        self, hass: HomeAssistant
+    ) -> None:
+        # When display_levels has never been saved, the field default
+        # should come from the device's preset instead of the global
+        # DEFAULT_DISPLAY_LEVELS constant, so devices like the
+        # reterminal_e1002 (256 levels) show their own capability
+        # pre-selected rather than an unrelated fallback.
+        flow = await _make_options_flow(
+            hass,
+            {
+                "update_interval": 60,
+                "device_model": "reterminal_e1002",
+            },
+        )
+        result = await flow.async_step_display_settings(None)
+
+        markers = {
+            k.schema: k
+            for k in result["data_schema"].schema
+            if hasattr(k, "schema")
+        }
+        assert markers["display_levels"].default() == 256
+
+    async def test_display_settings_prefers_stored_levels_over_preset(
+        self, hass: HomeAssistant
+    ) -> None:
+        # A previously saved display_levels value always wins over the
+        # device preset's default.
+        flow = await _make_options_flow(
+            hass,
+            {
+                "update_interval": 60,
+                "device_model": "reterminal_e1002",
+                "display_levels": 16,
+            },
+        )
+        result = await flow.async_step_display_settings(None)
+
+        markers = {
+            k.schema: k
+            for k in result["data_schema"].schema
+            if hasattr(k, "schema")
+        }
+        assert markers["display_levels"].default() == 16
+
     async def test_display_settings_saves_optimize_toggle_on(
         self, hass: HomeAssistant
     ) -> None: