fix(web): a store install asks for a restart by the id it installed as

POST /plugins/install decides restart_required from whether config.json
already enables the plugin: the display loads a plugin when its enabled
flag changes, so one already enabled (a reinstall, or a config carried
over) keeps running the copy it loaded until a restart. The route read
that flag under the registry id. Weather, Music, Stocks and Leaderboard
install under the id their manifests declare (weather ->
ledmatrix-weather), which is the config section's id, so reinstalling an
enabled one never reported that a restart was needed.

Both the queued and the direct path now look up the installed id once
(#746's _installed_plugin_id) and use it for the plugin_id they answer
with and for the enabled check.

Tests: test/test_api_v3_install_restart_installed_id.py, through the
Flask test client, both paths.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/test_api_v3_install_restart_installed_id.py

@@ -0,0 +1,123 @@
+"""POST /plugins/install asks for a restart by the id the plugin installed as.
+
+A store install needs a display restart when config.json already enables the
+plugin (a reinstall, or a config carried over): the display loads a plugin
+when its ``enabled`` flag changes, and this flag did not. The route read the
+flag under the registry id it was given. An aliased entry installs under
+another id -- ``weather`` installs a directory whose manifest declares
+``ledmatrix-weather``, and its config section is ``ledmatrix-weather`` -- so
+reinstalling an enabled Weather never reported that a restart was needed,
+and the display kept running the old copy.
+"""
+
+import json
+from unittest.mock import MagicMock
+
+import pytest
+
+from test._api_v3_test_helpers import api_v3_client, api_v3_module  # noqa: F401
+
+INSTALL = "/api/v3/plugins/install"
+
+
+@pytest.fixture
+def store(api_v3_module, tmp_path):
+    """The store installs registry entry ``weather`` as ``installed_id``."""
+    manager = api_v3_module.api_v3.plugin_store_manager
+    manager.install_plugin.return_value = True
+    manager.get_registry_info.return_value = None
+    manager._find_plugin_path.return_value = None
+
+    def installs_as(installed_id):
+        path = tmp_path / installed_id
+        path.mkdir()
+        (path / "manifest.json").write_text(json.dumps({"id": installed_id}),
+                                            encoding="utf-8")
+        manager._find_plugin_path.side_effect = (
+            lambda pid: path if pid == "weather" else None)
+
+    manager.installs_as = installs_as
+    return manager
+
+
+@pytest.fixture
+def config(api_v3_module):
+    """config.json with an ``enabled`` flag for each plugin id given."""
+    def sections(enabled):
+        api_v3_module.api_v3.config_manager.load_config.return_value = {
+            plugin_id: {"enabled": flag} for plugin_id, flag in enabled.items()}
+    return sections
+
+
+@pytest.fixture
+def queued(api_v3_module):
+    queue = MagicMock()
+
+    def enqueue(operation_type, plugin_id, operation_callback=None):
+        queue.callback_result = operation_callback(MagicMock())
+        return "op-1"
+
+    queue.enqueue_operation.side_effect = enqueue
+    api_v3_module.api_v3.operation_queue = queue
+    return queue
+
+
+def _direct(client):
+    return client.post(INSTALL, json={"plugin_id": "weather"}).get_json()
+
+
+def _queued(client, queue):
+    client.post(INSTALL, json={"plugin_id": "weather"})
+    return queue.callback_result
+
+
+class TestDirectInstall:
+    def test_an_aliased_install_enabled_under_its_installed_id_asks_for_a_restart(
+            self, api_v3_client, store, config):
+        store.installs_as("ledmatrix-weather")
+        config({"ledmatrix-weather": True})
+        body = _direct(api_v3_client)
+        assert body["status"] == "success"
+        assert body["restart_required"] is True
+        assert body["restart_message"]
+
+    def test_an_enabled_section_under_the_registry_id_alone_does_not(
+            self, api_v3_client, store, config):
+        """The display knows the plugin as ledmatrix-weather; nothing runs
+        under a section called weather."""
+        store.installs_as("ledmatrix-weather")
+        config({"weather": True})
+        assert _direct(api_v3_client)["restart_required"] is False
+
+    def test_an_aliased_install_that_is_not_enabled_needs_no_restart(
+            self, api_v3_client, store, config):
+        store.installs_as("ledmatrix-weather")
+        config({"ledmatrix-weather": False})
+        assert _direct(api_v3_client)["restart_required"] is False
+
+    def test_an_install_under_its_own_id_is_unchanged(self, api_v3_client, store, config):
+        store.installs_as("weather")
+        config({"weather": True})
+        assert _direct(api_v3_client)["restart_required"] is True
+
+    def test_an_install_that_cannot_be_found_uses_the_requested_id(
+            self, api_v3_client, store, config):
+        config({"weather": True})
+        assert _direct(api_v3_client)["restart_required"] is True
+
+
+class TestQueuedInstall:
+    def test_an_aliased_install_enabled_under_its_installed_id_asks_for_a_restart(
+            self, api_v3_client, store, config, queued):
+        store.installs_as("ledmatrix-weather")
+        config({"ledmatrix-weather": True})
+        result = _queued(api_v3_client, queued)
+        assert result["success"] is True
+        assert result["restart_required"] is True
+        assert result["restart_message"]
+
+    def test_an_enabled_section_under_the_registry_id_alone_does_not(
+            self, api_v3_client, store, config, queued):
+        store.installs_as("ledmatrix-weather")
+        config({"weather": True})
+        assert _queued(api_v3_client, queued)["restart_required"] is False