feat(media_player): source list + native select_source from the app list (t47 A)

The last piece a universal-media-player replacement needs: a dropdown of the apps,
an answer to what is on screen, and a way to pick one — all reading ONE app directory
(the user's Apps map, else DEFAULT_APP_DIRECTORY), so the dropdown can never offer a
name the launch path cannot resolve. That invariant is pinned by a test that walks
source_list and resolves every entry.

* `source_list` — friendly names in directory order (the user's map order, or the
  curated list), from a new `_app_directory` accessor that the browse tree now shares.
* `source` — the foreground app's resolved name via the existing `resolve_app_name`
  chain (map → cached device-manifest label → raw package), i.e. exactly `app_name`,
  so the media player and the Current App sensor cannot disagree.
* `select_source(name)` — a configured select_source script still takes precedence
  (t44, unchanged: selecting a source can be more than launching an app); without one
  the name is resolved back to its package and launched over the shared
  `play_media("app", …)` path, so the native semantics are the ones play_media already
  had. Accepts a raw package id (what the browse tree publishes) and matches names
  case-insensitively; an unknown or empty name raises
  ServiceValidationError(translation_domain="nvidia_shield",
  translation_key="unknown_source", translation_placeholders={"source": …}) — a
  translated error, never a silent no-op — with new copy in BOTH strings files.
* SELECT_SOURCE is advertised when EITHER a select_source script is configured OR
  source_list is non-empty; VOLUME_SET stays script-only (the protocol has no
  absolute-volume key), and the two flags are pinned as independent.

Two t44 tests were updated because this is a deliberate behaviour change: "no native
path" is now only true of volume_set, and SELECT_SOURCE is advertised by default
because the curated directory always offers something.

Also: rewriting the strings files re-indented the seven script labels added in t44
(they were valid JSON but sat two levels shallow); the diff there is that fix plus
the new key.

Verified: 441 passed / 2 skipped, ruff clean, drift engine exit 0 under real HA
(23 modules, 59 imports, 157 relative imports, 36 call arguments, 7 awaited HA calls).

custom_components/nvidia_shield/media_player.py

@@ -672,13 +672,13 @@ class NvidiaShieldMediaPlayer(MediaPlayerEntity):
             else:
                 features = _BASE_FEATURES
 
-        # t44: a command that exists ONLY as a script still has to be reachable, and
-        # the feature flag is what makes HA offer it. volume_set and select_source
-        # have no native path at all, so they appear exactly when configured —
-        # without a script the feature set is what it always was.
+        # t44/t47: a command that exists ONLY as a script still has to be
+        # reachable, and the feature flag is what makes HA offer it. volume_set has
+        # no native path at all; select_source appears when EITHER a script is
+        # configured OR there is a source list to offer (t47 gave it a native path).
         if self._script_for("volume_set"):
             features |= MediaPlayerEntityFeature.VOLUME_SET
-        if self._script_for("select_source"):
+        if self._script_for("select_source") or self.source_list:
             features |= MediaPlayerEntityFeature.SELECT_SOURCE
         return features
 
@@ -702,6 +702,34 @@ class NvidiaShieldMediaPlayer(MediaPlayerEntity):
         """The user's apps name/icon map (P4-1 options editor)."""
         return self._entry.options.get(CONF_APP_NAME_MAP) or {}
 
+    @property
+    def _app_directory(self) -> dict:
+        """Launchable apps: the user's map, else the curated default (P4-1).
+
+        ONE source for the browse tree, the source list and the reverse lookup, so
+        the dropdown can never offer a name the launch path cannot resolve.
+        """
+        return self._entry.options.get(CONF_APP_NAME_MAP) or DEFAULT_APP_DIRECTORY
+
+    @property
+    def source_list(self) -> list[str]:
+        """The apps as friendly names — the dropdown a UMP replacement reads (t47).
+
+        Directory order (the user's map order, or the curated list), so rebuilding
+        the page does not shuffle it.
+        """
+        return [str(name) for name in self._app_directory.values()]
+
+    @property
+    def source(self) -> str | None:
+        """The foreground app's friendly name — the same chain as app_name (t47).
+
+        ``resolve_app_name``: the user's map, then the cached device-manifest label,
+        then the raw package. Same answer as the Current App sensor, so a
+        universal-media-player replacement cannot see two different truths.
+        """
+        return self.app_name
+
     @property
     def app_name(self):
         """P5-1 resolution order — explicit override first:
@@ -1029,14 +1057,42 @@ class NvidiaShieldMediaPlayer(MediaPlayerEntity):
         """
         await self._script_served("volume_set", {SCRIPT_VAR_LEVEL: volume})
 
-    async def async_select_source(self, source):
-        """Select a source — reachable only with a script (t44).
+    def _source_package(self, source) -> str | None:
+        """The package behind a source name, or a package id passed through (t47)."""
+        directory = self._app_directory
+        wanted = str(source or "").strip()
+        if not wanted:
+            return None
+        if wanted in directory:
+            # an automation may hand us the package directly; that is what the
+            # browse tree publishes as media_content_id
+            return wanted
+        folded = wanted.casefold()
+        for package, name in directory.items():
+            if str(name).casefold() == folded:
+                return package
+        return None
 
-        The integration has no native source selection (app launching goes through
-        play_media with the app map). A script for this command is the hook for an
-        AVR input or anything else that has to move with the Shield.
+    async def async_select_source(self, source):
+        """Select an app by its friendly name (t47) — script first, else launch it.
+
+        A configured ``select_source`` script keeps precedence (t44: selecting a
+        source can be more than launching an app — an AVR input, a speaker switch).
+        Without one the name is resolved back to its package through the SAME
+        directory the source list came from and launched over the shared
+        ``play_media("app", …)`` path, so a universal-media-player replacement gets
+        the native behaviour. An unknown name is an error, never a silent no-op.
         """
-        await self._script_served("select_source", {SCRIPT_VAR_APP_NAME: source})
+        if await self._script_served("select_source", {SCRIPT_VAR_APP_NAME: source}):
+            return
+        package = self._source_package(source)
+        if package is None:
+            raise ServiceValidationError(
+                translation_domain=DOMAIN,
+                translation_key="unknown_source",
+                translation_placeholders={"source": str(source)},
+            )
+        await self.async_play_media(MediaType.APP, package)
 
     async def _remote_key_cmd(self, remote_key: str, adb_key: str) -> None:
         """Simple key command without intent bookkeeping: protocol → ADB keyevent."""
@@ -1128,7 +1184,7 @@ class NvidiaShieldMediaPlayer(MediaPlayerEntity):
         removed a name media_player has not exported for a long time, which
         made every real browse raise.
         """
-        app_map = self._entry.options.get(CONF_APP_NAME_MAP) or DEFAULT_APP_DIRECTORY
+        app_map = self._app_directory
         children = [
             BrowseMedia(
                 title=name,

custom_components/nvidia_shield/strings.json

@@ -107,13 +107,13 @@
           "channel_digit_delay": "Channel digit delay (seconds)",
           "channel_send_enter": "Send ENTER after channel digits",
           "script_turn_on": "Turn on script",
-      "script_turn_off": "Turn off script",
-      "script_volume_up": "Volume up script",
-      "script_volume_down": "Volume down script",
-      "script_volume_set": "Volume set script",
-      "script_volume_mute": "Mute script",
-      "script_select_source": "Select source script",
-      "logcat_events": "Instant app detection (logcat stream)"
+          "script_turn_off": "Turn off script",
+          "script_volume_up": "Volume up script",
+          "script_volume_down": "Volume down script",
+          "script_volume_set": "Volume set script",
+          "script_volume_mute": "Mute script",
+          "script_select_source": "Select source script",
+          "logcat_events": "Instant app detection (logcat stream)"
         },
         "data_description": {
           "jellyfin_entity": "The Jellyfin media_player for this Shield. Stream details come from the HA Jellyfin integration \u2014 no extra setup needed.",
@@ -162,6 +162,10 @@
     "adb_unavailable": {
       "title": "ADB unavailable",
       "message": "The ADB connection of {entity_id} is down \u2014 command not sent."
+    },
+    "unknown_source": {
+      "title": "Unknown source",
+      "message": "'{source}' is not one of this Shield's apps. Use a name from the source list \u2014 the app names from the Apps map, or the built-in list when no map is set."
     }
   },
   "entity": {

custom_components/nvidia_shield/translations/en.json

@@ -107,13 +107,13 @@
           "channel_digit_delay": "Channel digit delay (seconds)",
           "channel_send_enter": "Send ENTER after channel digits",
           "script_turn_on": "Turn on script",
-      "script_turn_off": "Turn off script",
-      "script_volume_up": "Volume up script",
-      "script_volume_down": "Volume down script",
-      "script_volume_set": "Volume set script",
-      "script_volume_mute": "Mute script",
-      "script_select_source": "Select source script",
-      "logcat_events": "Instant app detection (logcat stream)"
+          "script_turn_off": "Turn off script",
+          "script_volume_up": "Volume up script",
+          "script_volume_down": "Volume down script",
+          "script_volume_set": "Volume set script",
+          "script_volume_mute": "Mute script",
+          "script_select_source": "Select source script",
+          "logcat_events": "Instant app detection (logcat stream)"
         },
         "data_description": {
           "jellyfin_entity": "The Jellyfin media_player for this Shield. Stream details come from the HA Jellyfin integration \u2014 no extra setup needed.",
@@ -162,6 +162,10 @@
     "adb_unavailable": {
       "title": "ADB unavailable",
       "message": "The ADB connection of {entity_id} is down \u2014 command not sent."
+    },
+    "unknown_source": {
+      "title": "Unknown source",
+      "message": "'{source}' is not one of this Shield's apps. Use a name from the source list \u2014 the app names from the Apps map, or the built-in list when no map is set."
     }
   },
   "entity": {