[PowerDisplay] Add stable profile IDs (#49175)

## Summary of the Pull Request

Gives every saved PowerDisplay profile a stable, auto-incrementing
integer ID and makes the app address profiles by that ID instead of by
name. Duplicate profile names are allowed, renames preserve identity,
and LightSwitch stores stable profile references.

> Split out of the PowerDisplay CLI branch (#48632). CLI-specific
contracts and commands remain in that stacked PR.

## PR Checklist

- [x] **Closes:** N/A - split from #48632.
- [x] **Communication:** Discussed with core contributors.
- [x] **Tests:** Added and passing in `PowerDisplay.Lib.UnitTests`.
- [x] **Localization:** The composed profile label uses a shared
localized format resource.
- [x] **New binaries:** None.
- [x] **Documentation updated:**
`doc/devdocs/modules/powerdisplay/design.md`.

## Implementation

### Profile model and persistence

- `PowerDisplayProfile.Id` is the stable JSON `id`; `0` means
unassigned.
- `PowerDisplayProfiles.NextId` is monotonic and IDs are never reused.
- `SetProfile` assigns IDs to new profiles and replaces existing
profiles by ID.
- Duplicate names are supported; name lookup remains only for migration
of legacy references.
- `ProfileStore` serializes cross-process load/modify/save operations
with a named mutex and atomically replaces `profiles.json`.
- Production callers use asynchronous `ProfileHelper` APIs.

### Migration and application

- Initial PowerDisplay discovery assigns missing profile IDs and
migrates legacy monitor IDs.
- LightSwitch legacy name references are reconciled to IDs and written
back to the current typed settings schema.
- Native LightSwitch publishes pure light/dark theme events;
PowerDisplay exclusively validates profile enablement and stable IDs.
- Settings UI and Named Pipe ApplyProfile actions send invariant
positive profile IDs.
- PowerDisplay validates the ID, loads the current profile, and applies
its monitor settings.

### Settings UI

- Create, edit, apply, and delete operations use stable IDs.
- LightSwitch selectors store profile IDs and keep legacy name fields
only for migration.
- Profile lists use a localized name-and-ID label so duplicate names
remain distinguishable.

## Accepted Trade-offs

- Profile ID migration remains dependent on the initial monitor
discovery; a failed or delayed discovery can temporarily hide legacy
ID-less profiles.
- The one-time PowerDisplay LightSwitch migration rewrites the complete
current typed settings object and does not add a new cross-process
settings transaction.

## Validation

- Built the affected x64 Debug projects with the repository build
scripts.
- `PowerDisplay.Lib.UnitTests`: 186 passed, 0 failed.

---------

Co-authored-by: Yu Leng (from Dev Box) <yuleng@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

doc/devdocs/modules/powerdisplay/design.md

@@ -193,26 +193,18 @@ src/modules/powerdisplay/
 │   │   └── PInvoke.cs                # P/Invoke declarations
 │   ├── Interfaces/
 │   │   ├── IMonitorController.cs     # Controller abstraction
-│   │   ├── IMonitorData.cs           # Monitor data interface
-│   │   └── IProfileService.cs        # Profile service interface
+│   │   └── IMonitorData.cs           # Monitor data interface
 │   ├── Models/
 │   │   ├── Monitor.cs                # Runtime monitor data
 │   │   ├── MonitorCapabilities.cs    # Monitor capability flags
 │   │   ├── MonitorOperationResult.cs # Operation result
 │   │   ├── MonitorStateEntry.cs      # Persisted monitor state
 │   │   ├── MonitorStateFile.cs       # State file schema
-│   │   ├── PowerDisplayProfile.cs    # Profile definition
-│   │   ├── PowerDisplayProfiles.cs   # Profile collection
-│   │   ├── ProfileMonitorSetting.cs  # Per-monitor profile settings
-│   │   ├── ColorPresetItem.cs        # Color preset UI item
 │   │   ├── VcpCapabilities.cs        # Parsed VCP capabilities
 │   │   └── VcpFeatureValue.cs        # VCP feature value (current/min/max)
-│   ├── Serialization/
-│   │   └── ProfileSerializationContext.cs  # JSON source generation
 │   ├── Services/
 │   │   ├── DisplayRotationService.cs # Display rotation via ChangeDisplaySettingsEx
-│   │   ├── MonitorStateManager.cs    # State persistence (debounced save) and restore on startup
-│   │   └── ProfileService.cs         # Profile persistence
+│   │   └── MonitorStateManager.cs    # State persistence (debounced save) and restore on startup
 │   ├── Utils/
 │   │   ├── ColorTemperatureHelper.cs # Color temp utilities
 │   │   ├── EventHelper.cs            # Windows Event utilities
@@ -221,11 +213,19 @@ src/modules/powerdisplay/
 │   │   ├── MonitorMatchingHelper.cs  # Profile-to-monitor matching
 │   │   ├── MonitorValueConverter.cs  # Value conversion utilities
 │   │   ├── PnpIdHelper.cs            # PnP manufacturer ID lookup
-│   │   ├── ProfileHelper.cs          # Profile helper utilities
 │   │   ├── SimpleDebouncer.cs        # Generic debouncer
 │   │   └── VcpNames.cs               # VCP code and value name lookup
 │   └── PathConstants.cs              # File path constants
 │
+├── PowerDisplay.Models/              # Shared profile models and persistence
+│   ├── ColorPresetItem.cs             # Color preset UI item
+│   ├── PowerDisplayProfile.cs         # Profile definition
+│   ├── PowerDisplayProfiles.cs        # Profile collection
+│   ├── ProfileMonitorSetting.cs       # Per-monitor profile settings
+│   ├── ProfileHelper.cs               # Shared asynchronous profile entry points
+│   ├── ProfileStore.cs                # Atomic cross-process profile persistence
+│   └── ProfileSerializationContext.cs # JSON source generation
+│
 ├── PowerDisplay/                     # WinUI 3 application
 │   ├── Assets/                       # App icons and images
 │   ├── Configuration/
@@ -304,7 +304,6 @@ flowchart TB
 
         subgraph PowerDisplayLib["PowerDisplay.Lib"]
             subgraph Services
-                ProfileService
                 MonitorStateManager
                 DisplayRotationService
             end
@@ -316,6 +315,11 @@ flowchart TB
                 PnpIdHelper["PnpIdHelper<br/>(Manufacturer Names)"]
             end
         end
+
+        subgraph PowerDisplayModels["PowerDisplay.Models"]
+            ProfileHelper
+            ProfileStore
+        end
     end
 
     subgraph Storage["Persistent Storage"]
@@ -338,13 +342,14 @@ flowchart TB
     ThemeChangedEvent --> LightSwitchService
 
     %% App internal
-    LightSwitchService -.->|"Get profile name"| MainViewModel
+    LightSwitchService -.->|"Get profile id"| MainViewModel
     MainViewModel --> MonitorViewModel
     MonitorViewModel --> MonitorManager
     DisplayChangeWatcher -.->|"DisplayChanged event"| MainViewModel
 
-    %% App to Lib services
-    MainViewModel --> ProfileService
+    %% App to services and profile persistence
+    MainViewModel --> ProfileHelper
+    ProfileHelper --> ProfileStore
     MonitorViewModel --> MonitorStateManager
     MonitorManager --> Drivers
     MonitorManager --> DisplayRotationService
@@ -352,8 +357,8 @@ flowchart TB
     %% Utils used during discovery
     WmiController --> PnpIdHelper
 
-    %% Services to Storage
-    ProfileService --> ProfilesJson
+    %% Persistence to Storage
+    ProfileStore --> ProfilesJson
     MonitorStateManager --> MonitorStateJson
 
     %% Drivers to Hardware
@@ -1080,7 +1085,7 @@ flowchart TB
         StateManager["LightSwitchStateManager"]
         ThemeEval["Theme Evaluation<br/>(Time/System)"]
         LightSwitchSettings["LightSwitchSettings"]
-        NotifyPD["NotifyPowerDisplay(isLight)"]
+        NotifyPD["NotifyPowerDisplayThemeChanged(isLight)"]
     end
 
     subgraph PowerDisplayModule["PowerDisplay Module (C#)"]
@@ -1090,7 +1095,8 @@ flowchart TB
             MainViewModel["MainViewModel"]
         end
 
-        ProfileService["ProfileService"]
+        ProfileHelper["ProfileHelper<br/>(PowerDisplay.Models)"]
+        ProfileStore["ProfileStore"]
         MonitorVMs["MonitorViewModels"]
         Controllers["IMonitorController"]
     end
@@ -1113,17 +1119,18 @@ flowchart TB
     ThemeEval -->|"Time boundary<br/>or manual"| StateManager
     StateManager --> LightSwitchSettings
     StateManager --> NotifyPD
-    NotifyPD -->|"isLight=true"| LightEvent
-    NotifyPD -->|"isLight=false"| DarkEvent
+    NotifyPD -->|"pure light theme event"| LightEvent
+    NotifyPD -->|"pure dark theme event"| DarkEvent
 
     %% PowerDisplay flow - theme determined from event
     LightEvent -->|"Event signaled"| EventWaiter
     DarkEvent -->|"Event signaled"| EventWaiter
     EventWaiter -->|"isLightMode"| LightSwitchSvc
-    LightSwitchSvc -->|"GetProfileForTheme()"| LSSettingsJson
-    LightSwitchSvc -->|"Profile name"| MainViewModel
-    MainViewModel -->|"LoadProfiles()"| ProfileService
-    ProfileService <--> PDProfilesJson
+    LightSwitchSvc -->|"GetProfileIdForTheme()"| LSSettingsJson
+    LightSwitchSvc -->|"Profile id"| MainViewModel
+    MainViewModel -->|"LoadProfilesAsync()"| ProfileHelper
+    ProfileHelper --> ProfileStore
+    ProfileStore <--> PDProfilesJson
     MainViewModel -->|"ApplyProfileAsync()"| MonitorVMs
     MonitorVMs --> Controllers
     Controllers --> Monitors
@@ -1135,20 +1142,25 @@ flowchart TB
     style FileSystem fill:#fffde7
 ```
 
+Native LightSwitch treats these named events as pure theme-change notifications and does not parse PowerDisplay profile enablement, names, or IDs. PowerDisplay reads the typed LightSwitch settings after receiving the event and is the sole authority that validates and applies the configured profile.
+
 ### LightSwitch Settings JSON Structure
 
 ```json
 {
   "properties": {
-    "apply_monitor_settings": { "value": true },
-    "enable_light_mode_profile": { "value": true },
-    "light_mode_profile": { "value": "Productivity" },
-    "enable_dark_mode_profile": { "value": true },
-    "dark_mode_profile": { "value": "Night Mode" }
+    "enableLightModeProfile": { "value": true },
+    "lightModeProfile": { "value": "" },
+    "lightModeProfileId": { "value": 3 },
+    "enableDarkModeProfile": { "value": true },
+    "darkModeProfile": { "value": "" },
+    "darkModeProfileId": { "value": 7 }
   }
 }
 ```
 
+The name fields are retained only for migration from pre-ID settings; current code persists and resolves the positive ID fields.
+
 ---
 
 ## Data Flow and Communication
@@ -1354,7 +1366,8 @@ sequenceDiagram
     participant SettingsPage as PowerDisplayPage
     participant ViewModel as PowerDisplayViewModel
     participant ProfileDialog as ProfileEditorDialog
-    participant ProfileService
+    participant ProfileHelper
+    participant ProfileStore
     participant FileSystem as profiles.json
 
     User->>SettingsPage: Clicks "Add Profile" button
@@ -1369,20 +1382,21 @@ sequenceDiagram
     User->>ProfileDialog: Clicks "Save"
 
     ProfileDialog->>ProfileDialog: Validate inputs
-    Note over ProfileDialog: Check name unique,<br/>at least one monitor selected
+    Note over ProfileDialog: Check non-empty name,<br/>at least one monitor selected
 
     ProfileDialog-->>ViewModel: ResultProfile (PowerDisplayProfile)
 
-    ViewModel->>ProfileService: AddOrUpdateProfile(profile)
+    ViewModel->>ProfileHelper: ProfileHelper.AddOrUpdateProfileAsync(profile)
+    ProfileHelper->>ProfileStore: AddOrUpdateProfileAsync(profile)
 
-    ProfileService->>ProfileService: lock(_lock)
-    ProfileService->>FileSystem: Read profiles.json
-    FileSystem-->>ProfileService: Existing profiles
-    ProfileService->>ProfileService: Add/update profile in collection
-    ProfileService->>ProfileService: Set LastUpdated = DateTime.Now
-    ProfileService->>FileSystem: Write profiles.json
-    FileSystem-->>ProfileService: Success
-    ProfileService-->>ViewModel: true
+    ProfileStore->>ProfileStore: Acquire process lock and named mutex
+    ProfileStore->>FileSystem: Read profiles.json
+    FileSystem-->>ProfileStore: Existing profiles
+    ProfileStore->>ProfileStore: Assign id and update profile
+    ProfileStore->>FileSystem: Write temp file and atomically replace profiles.json
+    FileSystem-->>ProfileStore: Success
+    ProfileStore-->>ProfileHelper: Completed
+    ProfileHelper-->>ViewModel: Completed
 
     ViewModel->>ViewModel: RefreshProfilesList()
     ViewModel-->>SettingsPage: PropertyChanged(Profiles)
@@ -1401,7 +1415,7 @@ sequenceDiagram
     participant EventWaiter as NativeEventWaiter
     participant LSSvc as LightSwitchService
     participant MainVM as MainViewModel
-    participant ProfileService
+    participant ProfileHelper
     participant MonitorVM as MonitorViewModel
     participant Controller as IMonitorController
     participant Monitor as Physical Monitor
@@ -1412,8 +1426,8 @@ sequenceDiagram
     LightSwitch->>LightSwitch: EvaluateAndApplyIfNeeded()
     LightSwitch->>LightSwitch: ApplyTheme(isLight)
 
-    LightSwitch->>LightSwitch: NotifyPowerDisplay(isLight)
-    Note over LightSwitch: Check if profile enabled
+    LightSwitch->>LightSwitch: NotifyPowerDisplayThemeChanged(isLight)
+    Note over LightSwitch: Publish the resulting theme only;<br/>PowerDisplay owns profile validation
 
     alt isLight == true
         LightSwitch->>WinEvent: SetEvent("Local\\PowerToys_LightSwitch_LightTheme")
@@ -1425,16 +1439,16 @@ sequenceDiagram
     EventWaiter->>WinEvent: WaitAny([lightEvent, darkEvent]) returns index
 
     Note over EventWaiter: Theme determined from event:<br/>index 0 = Light, index 1 = Dark
-    EventWaiter->>LSSvc: GetProfileForTheme(isLightMode)
+    EventWaiter->>LSSvc: GetProfileIdForTheme(isLightMode)
     LSSvc->>LSSvc: Read LightSwitch/settings.json
-    LSSvc-->>EventWaiter: profileName (or null)
+    LSSvc-->>EventWaiter: profileId (or null)
 
-    EventWaiter->>MainVM: Dispatch to UI thread with profileName
+    EventWaiter->>MainVM: Dispatch to UI thread with profileId
 
-    MainVM->>ProfileService: LoadProfiles()
-    ProfileService-->>MainVM: PowerDisplayProfiles
+    MainVM->>ProfileHelper: LoadProfilesAsync()
+    ProfileHelper-->>MainVM: PowerDisplayProfiles
 
-    MainVM->>MainVM: Find profile by name
+    MainVM->>MainVM: Find profile by id
     MainVM->>MainVM: ApplyProfileAsync(profile.MonitorSettings)
 
     loop For each ProfileMonitorSetting