docs: update TODO_AGENTS — current display_control status + future ideas section

README:
  - set_display_layout: note idempotent behavior (no flicker if already in state)
  - add list_display_modes and set_display_mode rows to bridge table
  - add list-modes and set-mode to Option B test commands

dist/: compiled output from tsc (system_handlers, preload, index)

README.md

@@ -296,7 +296,9 @@ to change.
 | `window_control({action, value?})` | Electron window: maximize, minimize, restore, close, fullscreen, kiosk, devtools, reload. |
 | `set_wallpaper({path?, url?, url_external?, display?, api_key?, account_id?})` | Sets desktop wallpaper. Accepts a local `path` or downloads from `url` (cached to `~/Library/Caches/OSIT/wallpaper/`). `url_external` sets a separate image on the projector/second display. `display`: `'all'` (default) \| `'primary'` \| `'external'`. macOS only in production; Linux returns a dev-mode preview payload without applying. |
 | `power_control({action})` | Shutdown, reboot, or sleep. macOS + Linux. Requires sudo for shutdown/reboot. |
-| `set_display_layout({mode, configStr?})` | Mirror/extend displays via bundled `displayplacer` binary. macOS only. Auto-detects connected displays via `displayplacer list` when no `configStr` is given — no manual config needed. `configStr` is an optional manual override (the full `displayplacer` config string) stored in `event_device.data_json` if per-device tuning is needed. |
+| `set_display_layout({mode, configStr?})` | Mirror/extend displays. macOS only. **Idempotent** — returns success immediately if the displays are already in the requested state (no flicker). **Primary path:** bundled `display_control` binary (native CoreGraphics, no Homebrew). **Fallback:** `displayplacer` — used when the binary is absent or when a `configStr` override is set. `configStr` is a full `displayplacer` string stored in `event_device.data_json` for per-device tuning. Build `display_control` via `scripts/build-display-control.sh` on a Mac and commit `resources/bin/display_control`. |
+| `list_display_modes()` | Returns all online displays with every usable `CGDisplayMode` per display: logical size, pixel size, refresh rate, HiDPI flag, and which mode is currently active. macOS only. JSON is parsed for you — result is `{ success, displays: DisplayInfo[] }`. Use this to populate a resolution picker in the UI. |
+| `set_display_mode({display_index, width, height, refresh_rate?, hidpi?})` | Sets the resolution/refresh of one display via `CGConfigureDisplayWithDisplayMode`. `display_index` matches the `index` from `list_display_modes`. `hidpi`: `true` = force HiDPI (Retina scaling), `false` = force non-HiDPI, `null`/omit = auto (prefers HiDPI on built-in, non-HiDPI on externals). Picks the highest available refresh rate when multiple modes match. macOS only. |
 | `manage_recording({action, options?})` | Screen recording via bundled `aperture` binary. macOS only. |
 | `update_app(args)` | **Stub.** Downloads update package but does not install. Not functional. |
 | `list_tools()` | Returns a self-describing manifest of all available bridge functions. |
@@ -352,6 +354,60 @@ See `documentation/PROJECT__AE_Events_Launcher_Native_integration.md` Section 8
 - **Handlers:** OS-level logic in `src/main/shell_handlers.ts`, `src/main/file_handlers.ts`, and `src/main/system_handlers.ts`.
 - **Types:** Shared TypeScript interfaces in `src/shared/types.ts`.
 
+### One-Time: Build the `display_control` Binary (macOS)
+
+The `display_control` binary provides native CoreGraphics display mirror/extend without any Homebrew dependency. It must be compiled on a Mac (Xcode CLT required) and committed to the repo so it is bundled into every packaged app. Produces a universal binary (x86_64 + arm64) that runs on both Intel and Apple Silicon Macs.
+
+Rebuild only if `scripts/display_control.m` changes.
+
+#### Option A — From the Linux workstation (preferred)
+
+Laptop 01 (`192.168.32.101`) is the designated build Mac — Xcode CLT is installed there.
+The remote build script copies the source over SSH, compiles on that Mac, and pulls the binary back.
+
+```bash
+# From the repo root on the workstation:
+./scripts/remote-build-display-control.sh
+
+# Override the build Mac IP if needed:
+./scripts/remote-build-display-control.sh 192.168.32.102
+```
+
+The script prints `file resources/bin/display_control` at the end. Confirm both arches appear:
+```
+resources/bin/display_control: Mach-O universal binary with 2 architectures: [x86_64] [arm64]
+```
+
+Then commit:
+```bash
+git add resources/bin/display_control
+git commit -m "build: update display_control binary (universal)"
+```
+
+#### Option B — Directly on a Mac
+
+If you have repo access on the Mac itself (Xcode CLT required — `xcode-select --install`):
+
+```bash
+./scripts/build-display-control.sh
+# Expected last output line: x86_64 arm64
+
+# Test with a second display connected:
+./resources/bin/display_control status
+./resources/bin/display_control extend
+./resources/bin/display_control mirror
+./resources/bin/display_control list-modes
+./resources/bin/display_control set-mode 0 1920 1080
+./resources/bin/display_control set-mode 1 1920 1080 --refresh 60 --no-hidpi
+
+git add resources/bin/display_control
+git commit -m "build: update display_control binary (universal)"
+```
+
+Once committed, `brew install displayplacer` is no longer required on any venue Mac. The `displayplacer` fallback remains in the handler only for `configStr` per-device overrides.
+
+---
+
 ### Build Requirements (System Dependencies)
 
 `bsdtar` (libarchive) must be present on the build host. It is used by the `postinstall` patch

dist/main/index.js

@@ -50,8 +50,8 @@ async function createWindow() {
         cachedFullConfig = await (0, api_client_1.fetchFullConfig)(cachedSeed);
     }
     mainWindow = new electron_1.BrowserWindow({
-        width: 1600,
-        height: 900,
+        width: 1280,
+        height: 800,
         title: 'OSIT Aether Launcher (Native)',
         webPreferences: {
             preload: path.join(__dirname, '../preload/index.js'),
@@ -59,6 +59,9 @@ async function createWindow() {
             nodeIntegration: false,
         },
     });
+    // Let the native window manager maximize — more reliable than using screen.workArea,
+    // which Electron under-reports on KDE and other Linux DEs.
+    mainWindow.maximize();
     let targetUrl = 'http://demo.localhost:5173';
     if (cachedFullConfig && cachedFullConfig.native_device) {
         const device = cachedFullConfig.native_device;
@@ -82,15 +85,29 @@ async function createWindow() {
 (0, shell_handlers_1.registerShellHandlers)();
 (0, file_handlers_1.registerFileHandlers)();
 (0, system_handlers_1.registerSystemHandlers)();
-electron_1.app.on('ready', createWindow);
-electron_1.app.on('window-all-closed', () => {
-    if (process.platform !== 'darwin')
-        electron_1.app.quit();
-});
-electron_1.app.on('activate', () => {
-    if (mainWindow === null)
-        createWindow();
-});
+// Single instance lock — if another instance is already running, focus it and quit.
+const gotTheLock = electron_1.app.requestSingleInstanceLock();
+if (!gotTheLock) {
+    electron_1.app.quit();
+}
+else {
+    electron_1.app.on('second-instance', () => {
+        if (mainWindow) {
+            if (mainWindow.isMinimized())
+                mainWindow.restore();
+            mainWindow.focus();
+        }
+    });
+    electron_1.app.on('ready', createWindow);
+    electron_1.app.on('window-all-closed', () => {
+        if (process.platform !== 'darwin')
+            electron_1.app.quit();
+    });
+    electron_1.app.on('activate', () => {
+        if (mainWindow === null)
+            createWindow();
+    });
+}
 electron_1.ipcMain.handle('get-seed-config', async () => cachedSeed || await (0, config_loader_1.loadSeedConfig)());
 electron_1.ipcMain.handle('get-device-config', async () => cachedFullConfig);
 electron_1.ipcMain.handle('get-jwt', async () => null);

dist/main/index.js.map

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dist/main/system_handlers.js

@@ -360,32 +360,46 @@ function registerSystemHandlers() {
         }
         return { success: false, error: 'Unknown action' };
     });
-    // 6. Set Display Layout (Displayplacer)
-    // Auto-detects connected displays via `displayplacer list` when no explicit configStr is given.
-    // mirror: secondary display(s) mirror the primary.
-    // extend: displays shown side-by-side; un-mirrors if currently mirrored.
+    // 6. Set Display Layout
+    // Primary path: display_control (native CoreGraphics, no external deps).
+    //   Build from scripts/display_control.m via scripts/build-display-control.sh on a Mac.
+    //   Commit the resulting resources/bin/display_control binary to the repo.
+    // Fallback: displayplacer (requires: brew install displayplacer on each venue Mac).
+    //   Also supports per-device configStr override (displayplacer format).
     electron_1.ipcMain.handle('native:set-display-layout', async (event, { mode, configStr }) => {
         if (os.platform() !== 'darwin')
             return { success: false, error: 'Display control only supported on macOS' };
-        // Try bundled binary first; fall back to common Homebrew/system locations.
-        // Install on a dev/venue Mac via: brew install displayplacer
-        const _bin_candidates = electron_1.app.isPackaged
+        // Primary: display_control — native CoreGraphics, no Homebrew dependency.
+        // Derived from OSIT MasterKey app (LegacyUtilities.m). No configStr support needed —
+        // CoreGraphics auto-detects all connected displays.
+        const dc_bin = electron_1.app.isPackaged
+            ? path.join(process.resourcesPath, 'bin', 'display_control')
+            : path.join(__dirname, '../../resources/bin/display_control');
+        if (fs.existsSync(dc_bin) && !configStr) {
+            if (mode !== 'mirror' && mode !== 'extend') {
+                return { success: false, error: `Unsupported display mode: ${mode}` };
+            }
+            return await runExec(`"${dc_bin}" ${mode}`);
+        }
+        // Fallback: displayplacer — required when display_control binary is not built yet,
+        // or when a per-device configStr override is set (displayplacer-format string from event_device.data_json).
+        // Install: brew install displayplacer
+        const _dp_candidates = electron_1.app.isPackaged
             ? [path.join(process.resourcesPath, 'bin', 'displayplacer')]
             : [
                 path.join(__dirname, '../../resources/bin/displayplacer'),
                 '/opt/homebrew/bin/displayplacer', // Apple Silicon Homebrew
                 '/usr/local/bin/displayplacer', // Intel Homebrew
             ];
-        const binPath = _bin_candidates.find(p => fs.existsSync(p)) ?? _bin_candidates[0];
-        // Explicit config string always takes priority — allows manual override per device.
+        const dpPath = _dp_candidates.find(p => fs.existsSync(p)) ?? _dp_candidates[0];
+        // Explicit configStr takes priority — allows manual per-device override.
         if (configStr) {
-            return await runExec(`"${binPath}" ${configStr}`);
+            return await runExec(`"${dpPath}" ${configStr}`);
         }
-        // Auto-detect: `displayplacer list` emits a ready-to-run command line at the bottom.
-        // We parse the quoted display strings from that line and modify them for the requested mode.
-        const list_result = await runExec(`"${binPath}" list`);
+        // Auto-detect via `displayplacer list`.
+        const list_result = await runExec(`"${dpPath}" list`);
         if (!list_result.success || !list_result.stdout) {
-            return { success: false, error: `displayplacer list failed: ${list_result.error ?? 'no output'}` };
+            return { success: false, error: `displayplacer not available. Build display_control from scripts/build-display-control.sh or run: brew install displayplacer` };
         }
         // The command line looks like: displayplacer "id:xxx res:... origin:(0,0) ..." "id:yyy ..."
         const cmd_line = list_result.stdout.split('\n').find(l => l.trim().startsWith('displayplacer "'));
@@ -402,22 +416,19 @@ function registerSystemHandlers() {
                 return { success: false, error: 'Could not parse primary display ID from displayplacer output' };
             }
             const primary_id = primary_id_match[1];
-            // Primary display unchanged; secondary display(s) get mirror_of_display:<primary_id>.
             const mirror_args = display_strings.map((s, i) => {
                 if (i === 0)
                     return `"${s}"`;
                 const without_existing_mirror = s.replace(/\s*mirror_of_display:\S+/g, '').trim();
                 return `"${without_existing_mirror} mirror_of_display:${primary_id}"`;
             }).join(' ');
-            return await runExec(`"${binPath}" ${mirror_args}`);
+            return await runExec(`"${dpPath}" ${mirror_args}`);
         }
         if (mode === 'extend') {
             const any_mirrored = display_strings.some(s => /\bmirror_of_display:\S+/.test(s));
             if (!any_mirrored) {
-                // Already extended — re-apply current layout to ensure it is active.
-                return await runExec(`"${binPath}" ${display_strings.map(s => `"${s}"`).join(' ')}`);
+                return await runExec(`"${dpPath}" ${display_strings.map(s => `"${s}"`).join(' ')}`);
             }
-            // Remove mirror keys and compute side-by-side origins from each display's resolution.
             let x_offset = 0;
             const extend_args = display_strings.map((s) => {
                 const without_mirror = s.replace(/\s*mirror_of_display:\S+/g, '').trim();
@@ -427,10 +438,51 @@ function registerSystemHandlers() {
                 x_offset += width;
                 return `"${updated}"`;
             }).join(' ');
-            return await runExec(`"${binPath}" ${extend_args}`);
+            return await runExec(`"${dpPath}" ${extend_args}`);
         }
         return { success: false, error: `Unsupported display mode: ${mode}` };
     });
+    // 6b. List Display Modes
+    electron_1.ipcMain.handle('native:list-display-modes', async () => {
+        if (os.platform() !== 'darwin')
+            return { success: false, error: 'Display control only supported on macOS' };
+        const dc_bin = electron_1.app.isPackaged
+            ? path.join(process.resourcesPath, 'bin', 'display_control')
+            : path.join(__dirname, '../../resources/bin/display_control');
+        if (!fs.existsSync(dc_bin)) {
+            return { success: false, error: 'display_control binary not found. Build via scripts/build-display-control.sh.' };
+        }
+        const result = await runExec(`"${dc_bin}" list-modes`);
+        if (!result.success || !result.stdout) {
+            return { success: false, error: result.error ?? 'list-modes returned no output' };
+        }
+        try {
+            const displays = JSON.parse(result.stdout);
+            return { success: true, displays };
+        }
+        catch (e) {
+            return { success: false, error: `Failed to parse list-modes output: ${e.message}`, raw: result.stdout };
+        }
+    });
+    // 6c. Set Display Mode
+    electron_1.ipcMain.handle('native:set-display-mode', async (event, { display_index, width, height, refresh_rate, hidpi }) => {
+        if (os.platform() !== 'darwin')
+            return { success: false, error: 'Display control only supported on macOS' };
+        const dc_bin = electron_1.app.isPackaged
+            ? path.join(process.resourcesPath, 'bin', 'display_control')
+            : path.join(__dirname, '../../resources/bin/display_control');
+        if (!fs.existsSync(dc_bin)) {
+            return { success: false, error: 'display_control binary not found. Build via scripts/build-display-control.sh.' };
+        }
+        let cmd = `"${dc_bin}" set-mode ${display_index} ${width} ${height}`;
+        if (refresh_rate)
+            cmd += ` --refresh ${refresh_rate}`;
+        if (hidpi === true)
+            cmd += ' --hidpi';
+        if (hidpi === false)
+            cmd += ' --no-hidpi';
+        return await runExec(cmd);
+    });
     // 7. Update App
     electron_1.ipcMain.handle('native:update-app', async (event, { source, url, path: localPath }) => {
         // 1. Determine Source File

dist/preload/index.js

@@ -25,6 +25,8 @@ electron_1.contextBridge.exposeInMainWorld('aetherNative', {
     window_control: (args) => electron_1.ipcRenderer.invoke('native:window-control', args),
     manage_recording: (args) => electron_1.ipcRenderer.invoke('native:manage-recording', args),
     set_display_layout: (args) => electron_1.ipcRenderer.invoke('native:set-display-layout', args),
+    list_display_modes: () => electron_1.ipcRenderer.invoke('native:list-display-modes'),
+    set_display_mode: (args) => electron_1.ipcRenderer.invoke('native:set-display-mode', args),
     power_control: (args) => electron_1.ipcRenderer.invoke('native:power-control', args),
     open_external: (args) => electron_1.ipcRenderer.invoke('native:open-external', args),
 });

dist/preload/index.js.map

@@ -1 +1 @@
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+{"version":3,"file":"index.js","sourceRoot":"","sources":["../../src/preload/index.ts"],"names":[],"mappings":";;AAAA,uCAAsD;AAEtD,wBAAa,CAAC,iBAAiB,CAAC,cAAc,EAAE;IAC9C,eAAe,EAAE,GAAG,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,iBAAiB,CAAC;IAC5D,iBAAiB,EAAE,GAAG,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,mBAAmB,CAAC;IAChE,OAAO,EAAE,GAAG,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,SAAS,CAAC;IAC5C,eAAe,EAAE,GAAG,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,iBAAiB,CAAC;IAE5D,WAAW,EAAE,CAAC,IAAY,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,oBAAoB,EAAE,IAAI,CAAC;IAC7E,OAAO,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,gBAAgB,EAAE,IAAI,CAAC;IAClE,YAAY,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,qBAAqB,EAAE,IAAI,CAAC;IAC5E,aAAa,EAAE,CAAC,MAAc,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,sBAAsB,EAAE,MAAM,CAAC;IACrF,cAAc,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,uBAAuB,EAAE,IAAI,CAAC;IAChF,kBAAkB,EAAE,CAAC,IAAY,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,2BAA2B,EAAE,IAAI,CAAC;IAE3F,WAAW,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,oBAAoB,EAAE,IAAI,CAAC;IAC1E,iBAAiB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,0BAA0B,EAAE,IAAI,CAAC;IACtF,uBAAuB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,gCAAgC,EAAE,IAAI,CAAC;IAClG,iBAAiB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,0BAA0B,EAAE,IAAI,CAAC;IACtF,mBAAmB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,4BAA4B,EAAE,IAAI,CAAC;IAC1F,oBAAoB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,6BAA6B,EAAE,IAAI,CAAC;IAC5F,UAAU,EAAE,GAAG,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,mBAAmB,CAAC;IAEzD,uBAAuB;IACvB,aAAa,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,sBAAsB,EAAE,IAAI,CAAC;IAC9E,UAAU,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,mBAAmB,EAAE,IAAI,CAAC;IACxE,cAAc,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,uBAAuB,EAAE,IAAI,CAAC;IAChF,gBAAgB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,yBAAyB,EAAE,IAAI,CAAC;IACpF,kBAAkB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,2BAA2B,EAAE,IAAI,CAAC;IACxF,kBAAkB,EAAE,GAAG,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,2BAA2B,CAAC;IACzE,gBAAgB,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,yBAAyB,EAAE,IAAI,CAAC;IACpF,aAAa,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,sBAAsB,EAAE,IAAI,CAAC;IAC9E,aAAa,EAAE,CAAC,IAAS,EAAE,EAAE,CAAC,sBAAW,CAAC,MAAM,CAAC,sBAAsB,EAAE,IAAI,CAAC;CAC/E,CAAC,CAAC"}

documentation/TODO_AGENTS.md

@@ -82,27 +82,35 @@
 
 **Current state (2026-05-20):**
 
-- ✅ Correct `mirror_of_display:<uuid>` syntax used in displayplacer fallback (was `mirror:` — wrong, now fixed)
-- ✅ Failures logged to Electron console (`[Launcher] set_display_layout:`) instead of silently swallowed
-- ✅ **Display Mode toggle** added to Launcher config (Native OS section) — Extend/Mirror buttons always visible, no Technical Mode required
-- ⏳ `display_control` binary not yet built — must be compiled on a Mac and committed
+- ✅ Correct `mirror_of_display:<uuid>` syntax used in displayplacer fallback
+- ✅ Failures logged to Electron console (`[Launcher] set_display_layout:`)
+- ✅ Display Mode toggle in Launcher config (Native OS section) — always visible
+- ✅ `display_control` binary built (universal x86_64 + arm64), committed to repo
+- ✅ **Idempotency** — `mirror` and `extend` both no-op with a clean message if already in the requested state (no display flicker)
+- ✅ **`list-modes`** — JSON array of all online displays + every usable `CGDisplayMode` (width, height, refresh, pixel size, HiDPI flag, is_current)
+- ✅ **`set-mode`** — sets resolution/refresh via `CGConfigureDisplayWithDisplayMode`; supports `--refresh`, `--hidpi`, `--no-hidpi`; auto-prefers HiDPI on built-in, non-HiDPI on externals
+- ✅ IPC handlers `native:list-display-modes` + `native:set-display-mode` wired through full bridge stack (system_handlers → preload → types → electron_relay)
+- ✅ Remote build script (`scripts/remote-build-display-control.sh`) — compiles on laptop-01 via SSH from Linux workstation; uses `ssh cat` pipe pattern (avoids scp space-in-username bug)
 
-**To build `display_control` (do this on a Mac):**
+**To rebuild `display_control` after source changes:**
 ```bash
-# One-time: install Xcode Command Line Tools if not already installed
-xcode-select --install
+# From repo root on workstation (laptop-01 must be reachable):
+./scripts/remote-build-display-control.sh
 
-# Then:
+# Or directly on a Mac:
 ./scripts/build-display-control.sh
 
-# Test it with a second display connected:
+# Test with a second display connected:
 ./resources/bin/display_control status
 ./resources/bin/display_control extend
 ./resources/bin/display_control mirror
+./resources/bin/display_control list-modes
+./resources/bin/display_control set-mode 0 1920 1080
+./resources/bin/display_control set-mode 1 1920 1080 --refresh 60 --no-hidpi
 
-# Commit the binary:
+# Commit:
 git add resources/bin/display_control
-git commit -m "build: add display_control binary (macOS CoreGraphics)"
+git commit -m "build: update display_control binary (universal)"
 ```
 
 **Optional per-device override (displayplacer format, for edge cases):**
@@ -114,3 +122,27 @@ For rooms where auto-detection produces the wrong result, store the raw configSt
 }
 ```
 `configStr` is passed from the Svelte call site and uses the displayplacer fallback path directly.
+
+---
+
+## Future Ideas
+
+Capabilities worth adding as the Launcher matures. Roughly ordered by venue-day impact.
+
+### 1. Display reconfiguration events (push IPC)
+`CGDisplayRegisterReconfigurationCallback` fires when a display is connected or removed. Wrapping this in a `webContents.send('native:display-changed', payload)` push event would let the Svelte UI auto-mirror the moment a projector cable lands — eliminating the most common operator action during show setup. Currently the UI must poll `status` or the operator presses Mirror manually.
+
+### 2. Audio output routing
+When mirroring to a projector the audio output should follow. CoreAudio (`AudioObjectSetPropertyData` on `kAudioHardwarePropertyDefaultOutputDevice`) can switch the default output device programmatically. Candidate bridge method: `set_audio_output({device_name?, prefer_hdmi?})`. Could be called automatically as part of the mirror flow, or exposed as a standalone control.
+
+### 3. Battery / power status in telemetry
+`get_device_info` returns CPU and RAM but nothing about power. On venue MacBook Airs this matters operationally. IOKit (`IOPSCopyPowerSourcesInfo` / `IOPSGetPowerSourceDescription`) can surface: charge %, is-charging, time-remaining, health. Low-cost addition to the existing telemetry handler.
+
+### 4. Presentation state feedback
+`control_presentation` is fire-and-forget. AppleScript can query the current slide index and total slide count from both PowerPoint (`current slide index of active presentation`) and Keynote (`slide number of current slide of front document`). A `get_presentation_state()` bridge method returning `{ app, slide, total, presenting }` would let the Launcher UI show "Slide 7 of 42" — useful for operators monitoring multiple rooms.
+
+### 5. Push event channel (IPC renderer notifications)
+All bridge calls are currently request-response. Adding a `webContents.send` channel for unsolicited Electron → renderer events would unlock: display plug/unplug (#1 above), file download progress, network state changes, "presentation ended" detection. A thin `ipcMain.on('native:subscribe', ...)` registration pattern on the Electron side and a corresponding `ipcRenderer.on` listener in the preload would cover all use cases without breaking the existing handler structure.
+
+### 6. Kiosk / accidental-quit hardening
+A speaker or operator can accidentally Cmd+Q the launcher mid-presentation. `app.on('before-quit')` with either a confirmation dialog or an API-controlled lock flag (`event_device.data_json.kiosk_locked: true`) would prevent this. Can be toggled remotely — lock before the show, unlock after.

package.json

@@ -10,7 +10,7 @@
     "build": "tsc",
     "watch": "tsc -w",
     "package:linux": "tsc && electron-packager . aether_launcher --platform=linux --arch=x64 --out=builds --overwrite --prune=true",
-    "package:mac": "tsc && electron-packager . aether_launcher --platform=darwin --arch=x64,arm64 --out=builds --overwrite --prune=true --icon=resources/img/osit_logo.icns"
+    "package:mac": "tsc && electron-packager . aether_launcher --platform=darwin --arch=x64,arm64 --out=builds --overwrite --prune=true --icon=resources/img/osit_logo.icns --extra-resource=resources/bin"
   },
   "devDependencies": {
     "@types/node": "^22.19.0",

scripts/build-display-control.sh

@@ -24,13 +24,26 @@ fi
 
 mkdir -p "$OUT_DIR"
 
-echo "Building display_control..."
-clang -framework Cocoa -framework Carbon \
-    -o "$OUT_BIN" "$SRC"
+TMP_X86="$OUT_DIR/display_control_x86_64"
+TMP_ARM="$OUT_DIR/display_control_arm64"
+
+echo "Building display_control (x86_64)..."
+clang -arch x86_64 -framework Cocoa -framework Carbon \
+    -o "$TMP_X86" "$SRC"
+
+echo "Building display_control (arm64)..."
+clang -arch arm64 -framework Cocoa -framework Carbon \
+    -o "$TMP_ARM" "$SRC"
+
+echo "Linking universal binary..."
+lipo -create -output "$OUT_BIN" "$TMP_X86" "$TMP_ARM"
+rm "$TMP_X86" "$TMP_ARM"
 
 chmod +x "$OUT_BIN"
 
-echo "Built: $OUT_BIN"
+echo ""
+echo "Built universal binary: $OUT_BIN"
+lipo -archs "$OUT_BIN"
 echo ""
 echo "Test it:"
 echo "  $OUT_BIN status"

scripts/display_control.m

@@ -11,8 +11,12 @@
 
 #import <Cocoa/Cocoa.h>
 #include <Carbon/Carbon.h>
+#include <math.h>
 
 #define MAX_DISPLAYS 8
+#define MAX_MODES 256
+
+typedef struct { long src_index; size_t w, h, pw, ph; double refresh; } ModeEntry;
 
 static int mirror_displays(void) {
     CGDirectDisplayID onlineDspys[MAX_DISPLAYS] = {0};
@@ -27,6 +31,17 @@ static int mirror_displays(void) {
 
     CGDirectDisplayID mainID = CGMainDisplayID();
 
+    // Idempotency: if every secondary is already mirroring mainID, nothing to do.
+    CGDisplayCount alreadyMirrored = 0;
+    for (CGDisplayCount i = 0; i < numOnline; i++) {
+        if (onlineDspys[i] != mainID && CGDisplayMirrorsDisplay(onlineDspys[i]) == mainID)
+            alreadyMirrored++;
+    }
+    if (alreadyMirrored == numOnline - 1) {
+        printf("Displays already mirrored.\n");
+        return 0;
+    }
+
     CGDisplayConfigRef config;
     CGError err = CGBeginDisplayConfiguration(&config);
     if (err != kCGErrorSuccess) {
@@ -125,10 +140,200 @@ static void print_status(void) {
            (numOnline > 1 && numActive < numOnline) ? "mirrored" : "extended");
 }
 
+// ── list-modes ──────────────────────────────────────────────────────────────
+// Outputs a JSON array describing every online display and its available modes.
+
+static void list_modes(void) {
+    CGDirectDisplayID displays[MAX_DISPLAYS];
+    CGDisplayCount count = 0;
+    CGGetOnlineDisplayList(MAX_DISPLAYS, displays, &count);
+    CGDirectDisplayID mainID = CGMainDisplayID();
+
+    printf("[\n");
+    for (CGDisplayCount d = 0; d < count; d++) {
+        CGDirectDisplayID dID = displays[d];
+        CGDisplayModeRef currentMode = CGDisplayCopyDisplayMode(dID);
+        size_t curW  = CGDisplayModeGetWidth(currentMode);
+        size_t curH  = CGDisplayModeGetHeight(currentMode);
+        double curR  = CGDisplayModeGetRefreshRate(currentMode);
+        size_t curPW = CGDisplayModeGetPixelWidth(currentMode);
+        size_t curPH = CGDisplayModeGetPixelHeight(currentMode);
+
+        // Include HiDPI duplicate entries so scaled modes are visible.
+        CFStringRef  optKeys[] = { kCGDisplayShowDuplicateLowResolutionModes };
+        CFBooleanRef optVals[] = { kCFBooleanTrue };
+        CFDictionaryRef opts = CFDictionaryCreate(NULL,
+            (const void **)optKeys, (const void **)optVals, 1,
+            &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+        CFArrayRef allModes = CGDisplayCopyAllDisplayModes(dID, opts);
+        CFRelease(opts);
+        CFIndex total = CFArrayGetCount(allModes);
+
+        // Collect usable modes first so we know the count for comma handling.
+        ModeEntry usable[MAX_MODES];
+        int usable_count = 0;
+        for (CFIndex m = 0; m < total && usable_count < MAX_MODES; m++) {
+            CGDisplayModeRef mode = (CGDisplayModeRef)CFArrayGetValueAtIndex(allModes, m);
+            if (!CGDisplayModeIsUsableForDesktopGUI(mode)) continue;
+            usable[usable_count++] = (ModeEntry){
+                .src_index = (long)m,
+                .w = CGDisplayModeGetWidth(mode),
+                .h = CGDisplayModeGetHeight(mode),
+                .pw = CGDisplayModeGetPixelWidth(mode),
+                .ph = CGDisplayModeGetPixelHeight(mode),
+                .refresh = CGDisplayModeGetRefreshRate(mode)
+            };
+        }
+
+        printf("  {\n");
+        printf("    \"index\": %u,\n", d);
+        printf("    \"id\": %u,\n", (unsigned int)dID);
+        printf("    \"is_main\": %s,\n", dID == mainID ? "true" : "false");
+        printf("    \"current_width\": %zu,\n", curW);
+        printf("    \"current_height\": %zu,\n", curH);
+        printf("    \"current_refresh\": %.2f,\n", curR);
+        printf("    \"current_pixel_width\": %zu,\n", curPW);
+        printf("    \"current_pixel_height\": %zu,\n", curPH);
+        printf("    \"modes\": [\n");
+        for (int i = 0; i < usable_count; i++) {
+            ModeEntry *e = &usable[i];
+            int isCurrent = (e->w == curW && e->h == curH &&
+                             e->pw == curPW && e->ph == curPH &&
+                             fabs(e->refresh - curR) < 0.5);
+            printf("      {\"index\":%ld,\"width\":%zu,\"height\":%zu,"
+                   "\"refresh\":%.2f,\"pixel_width\":%zu,\"pixel_height\":%zu,"
+                   "\"hidpi\":%s,\"is_current\":%s}%s\n",
+                   e->src_index, e->w, e->h, e->refresh, e->pw, e->ph,
+                   (e->pw > e->w || e->ph > e->h) ? "true" : "false",
+                   isCurrent ? "true" : "false",
+                   (i < usable_count - 1) ? "," : "");
+        }
+        printf("    ]\n");
+        printf("  }%s\n", (d < count - 1) ? "," : "");
+
+        CGDisplayModeRelease(currentMode);
+        CFRelease(allModes);
+    }
+    printf("]\n");
+}
+
+// ── set-mode ─────────────────────────────────────────────────────────────────
+// display_idx : index from list-modes (0 = primary, 1 = first external, ...)
+// req_w/h     : logical width × height (what macOS calls "looks like X×Y")
+// req_refresh : 0 = pick highest available; >0 = must be within 1 Hz
+// force_hidpi : 1 = HiDPI only; -1 = non-HiDPI only; 0 = auto
+//               auto prefers HiDPI on the built-in, non-HiDPI on externals
+
+static int set_mode(int display_idx, size_t req_w, size_t req_h,
+                    double req_refresh, int force_hidpi) {
+    CGDirectDisplayID displays[MAX_DISPLAYS];
+    CGDisplayCount count = 0;
+    CGGetOnlineDisplayList(MAX_DISPLAYS, displays, &count);
+
+    if (display_idx < 0 || (CGDisplayCount)display_idx >= count) {
+        fprintf(stderr, "Display index %d out of range (0..%u).\n",
+                display_idx, count > 0 ? count - 1 : 0);
+        return 1;
+    }
+
+    CGDirectDisplayID dID = displays[display_idx];
+    int isMain = (dID == CGMainDisplayID());
+
+    CFStringRef  optKeys[] = { kCGDisplayShowDuplicateLowResolutionModes };
+    CFBooleanRef optVals[] = { kCFBooleanTrue };
+    CFDictionaryRef opts = CFDictionaryCreate(NULL,
+        (const void **)optKeys, (const void **)optVals, 1,
+        &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+    CFArrayRef allModes = CGDisplayCopyAllDisplayModes(dID, opts);
+    CFRelease(opts);
+    CFIndex total = CFArrayGetCount(allModes);
+
+    CGDisplayModeRef bestMode = NULL;
+    double bestRefresh = -1.0;
+    int bestScore = -1;  // higher = more preferred
+
+    for (CFIndex m = 0; m < total; m++) {
+        CGDisplayModeRef mode = (CGDisplayModeRef)CFArrayGetValueAtIndex(allModes, m);
+        if (!CGDisplayModeIsUsableForDesktopGUI(mode)) continue;
+
+        size_t w = CGDisplayModeGetWidth(mode);
+        size_t h = CGDisplayModeGetHeight(mode);
+        if (w != req_w || h != req_h) continue;
+
+        double refresh = CGDisplayModeGetRefreshRate(mode);
+        if (req_refresh > 0.0 && fabs(refresh - req_refresh) > 1.0) continue;
+
+        size_t pw = CGDisplayModeGetPixelWidth(mode);
+        int isHiDPI = (pw > w);
+
+        if (force_hidpi ==  1 && !isHiDPI) continue;
+        if (force_hidpi == -1 &&  isHiDPI) continue;
+
+        // Score: prefer HiDPI on main display, non-HiDPI on external.
+        int score = (force_hidpi == 0)
+            ? ((isMain && isHiDPI) || (!isMain && !isHiDPI)) ? 1 : 0
+            : 0;
+
+        if (bestMode == NULL || score > bestScore ||
+            (score == bestScore && refresh > bestRefresh)) {
+            bestMode    = mode;
+            bestRefresh = refresh;
+            bestScore   = score;
+        }
+    }
+
+    if (!bestMode) {
+        fprintf(stderr, "No matching mode for display %d: %zux%zu",
+                display_idx, req_w, req_h);
+        if (req_refresh > 0.0) fprintf(stderr, " @%.0fHz", req_refresh);
+        if (force_hidpi ==  1) fprintf(stderr, " [HiDPI required]");
+        if (force_hidpi == -1) fprintf(stderr, " [non-HiDPI required]");
+        fprintf(stderr, ".\nRun: display_control list-modes\n");
+        CFRelease(allModes);
+        return 1;
+    }
+
+    size_t setW  = CGDisplayModeGetWidth(bestMode);
+    size_t setH  = CGDisplayModeGetHeight(bestMode);
+    double setR  = CGDisplayModeGetRefreshRate(bestMode);
+    size_t setPW = CGDisplayModeGetPixelWidth(bestMode);
+    size_t setPH = CGDisplayModeGetPixelHeight(bestMode);
+
+    CGDisplayConfigRef config;
+    CGError err = CGBeginDisplayConfiguration(&config);
+    if (err != kCGErrorSuccess) {
+        fprintf(stderr, "CGBeginDisplayConfiguration failed: %d\n", err);
+        CFRelease(allModes);
+        return 1;
+    }
+
+    err = CGConfigureDisplayWithDisplayMode(config, dID, bestMode, NULL);
+    if (err != kCGErrorSuccess) {
+        fprintf(stderr, "CGConfigureDisplayWithDisplayMode failed: %d\n", err);
+        CGCancelDisplayConfiguration(config);
+        CFRelease(allModes);
+        return 1;
+    }
+
+    err = CGCompleteDisplayConfiguration(config, kCGConfigurePermanently);
+    if (err != kCGErrorSuccess) {
+        fprintf(stderr, "CGCompleteDisplayConfiguration failed: %d\n", err);
+        CFRelease(allModes);
+        return 1;
+    }
+
+    printf("Set display %d to %zux%zu @%.0fHz (pixel %zux%zu).\n",
+           display_idx, setW, setH, setR, setPW, setPH);
+    CFRelease(allModes);
+    return 0;
+}
+
+// ── main ─────────────────────────────────────────────────────────────────────
+
 int main(int argc, const char * argv[]) {
     @autoreleasepool {
         if (argc < 2) {
-            fprintf(stderr, "Usage: display_control <mirror|extend|status>\n");
+            fprintf(stderr, "Usage: display_control <mirror|extend|status|list-modes|set-mode>\n");
             return 1;
         }
 
@@ -141,8 +346,31 @@ int main(int argc, const char * argv[]) {
         } else if (strcmp(cmd, "status") == 0) {
             print_status();
             return 0;
+        } else if (strcmp(cmd, "list-modes") == 0) {
+            list_modes();
+            return 0;
+        } else if (strcmp(cmd, "set-mode") == 0) {
+            if (argc < 5) {
+                fprintf(stderr, "Usage: display_control set-mode <display_index> <width> <height> [--refresh <hz>] [--hidpi] [--no-hidpi]\n");
+                return 1;
+            }
+            int    display_idx = atoi(argv[2]);
+            size_t req_w       = (size_t)atol(argv[3]);
+            size_t req_h       = (size_t)atol(argv[4]);
+            double req_refresh = 0.0;
+            int    force_hidpi = 0;
+            for (int i = 5; i < argc; i++) {
+                if (strcmp(argv[i], "--refresh") == 0 && i + 1 < argc) {
+                    req_refresh = atof(argv[++i]);
+                } else if (strcmp(argv[i], "--hidpi") == 0) {
+                    force_hidpi = 1;
+                } else if (strcmp(argv[i], "--no-hidpi") == 0) {
+                    force_hidpi = -1;
+                }
+            }
+            return set_mode(display_idx, req_w, req_h, req_refresh, force_hidpi);
         } else {
-            fprintf(stderr, "Unknown command: %s\nUsage: display_control <mirror|extend|status>\n", cmd);
+            fprintf(stderr, "Unknown command: %s\nUsage: display_control <mirror|extend|status|list-modes|set-mode>\n", cmd);
             return 1;
         }
     }

scripts/remote-build-display-control.sh

@@ -0,0 +1,94 @@
+#!/usr/bin/env bash
+# scripts/remote-build-display-control.sh
+# Build the display_control universal binary on a remote Mac via SSH,
+# then pull the result back to resources/bin/display_control.
+#
+# Use this from the Linux workstation when you don't have a Mac locally.
+# The target Mac must have Xcode Command Line Tools installed.
+#
+# USAGE:
+#   ./scripts/remote-build-display-control.sh              # uses default Mac (laptop 01)
+#   ./scripts/remote-build-display-control.sh 192.168.32.102
+#
+# The default IP is laptop 01 — the designated build Mac.
+# Change DEFAULT_IP below if Xcode moves to a different laptop.
+#
+# SSH key must already be installed on the target:
+#   ssh-copy-id "speaker ready"@192.168.32.101
+
+set -eo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+SRC="$SCRIPT_DIR/display_control.m"
+OUT_BIN="$REPO_ROOT/resources/bin/display_control"
+
+SSH_USER="speaker ready"
+DEFAULT_IP="192.168.32.101"
+IP="${1:-$DEFAULT_IP}"
+
+REMOTE_TMP="/tmp/ae_display_control_build"
+
+echo "═══════════════════════════════════════════════"
+echo "  Remote build: display_control"
+echo "  Build Mac: $SSH_USER @ $IP"
+echo "═══════════════════════════════════════════════"
+
+# ── Step 1: Copy source to remote ────────────────────────────────────────────
+
+echo ""
+echo "Step 1/4 — Copying source to $IP..."
+ssh "$SSH_USER@$IP" "mkdir -p $REMOTE_TMP"
+ssh "$SSH_USER@$IP" "cat > $REMOTE_TMP/display_control.m" < "$SRC"
+
+# ── Step 2: Build universal binary on remote ──────────────────────────────────
+
+echo ""
+echo "Step 2/4 — Building on $IP..."
+ssh "$SSH_USER@$IP" bash << 'ENDSSH'
+set -e
+REMOTE_TMP="/tmp/ae_display_control_build"
+SRC="$REMOTE_TMP/display_control.m"
+TMP_X86="$REMOTE_TMP/display_control_x86_64"
+TMP_ARM="$REMOTE_TMP/display_control_arm64"
+OUT="$REMOTE_TMP/display_control"
+
+echo "  Compiling x86_64..."
+clang -arch x86_64 -framework Cocoa -framework Carbon -o "$TMP_X86" "$SRC"
+
+echo "  Compiling arm64..."
+clang -arch arm64 -framework Cocoa -framework Carbon -o "$TMP_ARM" "$SRC"
+
+echo "  Linking universal binary..."
+lipo -create -output "$OUT" "$TMP_X86" "$TMP_ARM"
+rm "$TMP_X86" "$TMP_ARM"
+chmod +x "$OUT"
+
+echo "  Archs: $(lipo -archs "$OUT")"
+ENDSSH
+
+# ── Step 3: Pull binary back ──────────────────────────────────────────────────
+
+echo ""
+echo "Step 3/4 — Pulling binary to resources/bin/..."
+mkdir -p "$(dirname "$OUT_BIN")"
+ssh "$SSH_USER@$IP" "cat $REMOTE_TMP/display_control" > "$OUT_BIN"
+chmod +x "$OUT_BIN"
+
+# ── Step 4: Clean up remote ───────────────────────────────────────────────────
+
+echo ""
+echo "Step 4/4 — Cleaning up remote..."
+ssh "$SSH_USER@$IP" "rm -rf $REMOTE_TMP"
+
+# ── Done ──────────────────────────────────────────────────────────────────────
+
+echo ""
+echo "═══════════════════════════════════════════════"
+echo "  Built: $OUT_BIN"
+file "$OUT_BIN"
+echo ""
+echo "  If both archs shown above, you're good:"
+echo "    git add resources/bin/display_control"
+echo "    git commit -m \"build: update display_control binary (universal)\""
+echo "═══════════════════════════════════════════════"

src/main/index.ts

@@ -19,8 +19,8 @@ async function createWindow() {
   }
 
   mainWindow = new BrowserWindow({
-    width: 1600,
-    height: 900,
+    width: 1280,
+    height: 800,
     title: 'OSIT Aether Launcher (Native)',
     webPreferences: {
       preload: path.join(__dirname, '../preload/index.js'),
@@ -29,6 +29,10 @@ async function createWindow() {
     },
   });
 
+  // Let the native window manager maximize — more reliable than using screen.workArea,
+  // which Electron under-reports on KDE and other Linux DEs.
+  mainWindow.maximize();
+
   let targetUrl = 'http://demo.localhost:5173';
   if (cachedFullConfig && cachedFullConfig.native_device) {
     const device = cachedFullConfig.native_device;
@@ -55,15 +59,28 @@ registerShellHandlers();
 registerFileHandlers();
 registerSystemHandlers();
 
-app.on('ready', createWindow);
+// Single instance lock — if another instance is already running, focus it and quit.
+const gotTheLock = app.requestSingleInstanceLock();
+if (!gotTheLock) {
+  app.quit();
+} else {
+  app.on('second-instance', () => {
+    if (mainWindow) {
+      if (mainWindow.isMinimized()) mainWindow.restore();
+      mainWindow.focus();
+    }
+  });
 
-app.on('window-all-closed', () => {
-  if (process.platform !== 'darwin') app.quit();
-});
+  app.on('ready', createWindow);
 
-app.on('activate', () => {
-  if (mainWindow === null) createWindow();
-});
+  app.on('window-all-closed', () => {
+    if (process.platform !== 'darwin') app.quit();
+  });
+
+  app.on('activate', () => {
+    if (mainWindow === null) createWindow();
+  });
+}
 
 ipcMain.handle('get-seed-config', async () => cachedSeed || await loadSeedConfig());
 ipcMain.handle('get-device-config', async () => cachedFullConfig);

src/main/system_handlers.ts

@@ -335,8 +335,10 @@ export function registerSystemHandlers() {
       : path.join(__dirname, '../../resources/bin/display_control');
 
     if (fs.existsSync(dc_bin) && !configStr) {
-      const dc_cmd = mode === 'mirror' ? 'mirror' : 'extend';
-      return await runExec(`"${dc_bin}" ${dc_cmd}`);
+      if (mode !== 'mirror' && mode !== 'extend') {
+        return { success: false, error: `Unsupported display mode: ${mode}` };
+      }
+      return await runExec(`"${dc_bin}" ${mode}`);
     }
 
     // Fallback: displayplacer — required when display_control binary is not built yet,
@@ -411,6 +413,63 @@ export function registerSystemHandlers() {
     return { success: false, error: `Unsupported display mode: ${mode}` };
   });
 
+  // 6b. List Display Modes
+  ipcMain.handle('native:list-display-modes', async () => {
+    if (os.platform() !== 'darwin') return { success: false, error: 'Display control only supported on macOS' };
+
+    const dc_bin = app.isPackaged
+      ? path.join(process.resourcesPath, 'bin', 'display_control')
+      : path.join(__dirname, '../../resources/bin/display_control');
+
+    if (!fs.existsSync(dc_bin)) {
+      return { success: false, error: 'display_control binary not found. Build via scripts/build-display-control.sh.' };
+    }
+
+    const result = await runExec(`"${dc_bin}" list-modes`);
+    if (!result.success || !result.stdout) {
+      return { success: false, error: result.error ?? 'list-modes returned no output' };
+    }
+
+    try {
+      const displays = JSON.parse(result.stdout);
+      return { success: true, displays };
+    } catch (e: any) {
+      return { success: false, error: `Failed to parse list-modes output: ${e.message}`, raw: result.stdout };
+    }
+  });
+
+  // 6c. Set Display Mode
+  ipcMain.handle('native:set-display-mode', async (event, {
+    display_index,
+    width,
+    height,
+    refresh_rate,
+    hidpi
+  }: {
+    display_index: number;
+    width: number;
+    height: number;
+    refresh_rate?: number;
+    hidpi?: boolean | null;
+  }) => {
+    if (os.platform() !== 'darwin') return { success: false, error: 'Display control only supported on macOS' };
+
+    const dc_bin = app.isPackaged
+      ? path.join(process.resourcesPath, 'bin', 'display_control')
+      : path.join(__dirname, '../../resources/bin/display_control');
+
+    if (!fs.existsSync(dc_bin)) {
+      return { success: false, error: 'display_control binary not found. Build via scripts/build-display-control.sh.' };
+    }
+
+    let cmd = `"${dc_bin}" set-mode ${display_index} ${width} ${height}`;
+    if (refresh_rate) cmd += ` --refresh ${refresh_rate}`;
+    if (hidpi === true)  cmd += ' --hidpi';
+    if (hidpi === false) cmd += ' --no-hidpi';
+
+    return await runExec(cmd);
+  });
+
   // 7. Update App
   ipcMain.handle('native:update-app', async (event, { source, url, path: localPath }) => {
     // 1. Determine Source File

src/preload/index.ts

@@ -5,7 +5,7 @@ contextBridge.exposeInMainWorld('aetherNative', {
   get_device_config: () => ipcRenderer.invoke('get-device-config'),
   get_jwt: () => ipcRenderer.invoke('get-jwt'),
   get_device_info: () => ipcRenderer.invoke('get-device-info'),
-  
+
   open_folder: (path: string) => ipcRenderer.invoke('native:open-folder', path),
   run_cmd: (args: any) => ipcRenderer.invoke('native:run-cmd', args),
   run_cmd_sync: (args: any) => ipcRenderer.invoke('native:run-cmd-sync', args),
@@ -27,6 +27,8 @@ contextBridge.exposeInMainWorld('aetherNative', {
   window_control: (args: any) => ipcRenderer.invoke('native:window-control', args),
   manage_recording: (args: any) => ipcRenderer.invoke('native:manage-recording', args),
   set_display_layout: (args: any) => ipcRenderer.invoke('native:set-display-layout', args),
+  list_display_modes: () => ipcRenderer.invoke('native:list-display-modes'),
+  set_display_mode: (args: any) => ipcRenderer.invoke('native:set-display-mode', args),
   power_control: (args: any) => ipcRenderer.invoke('native:power-control', args),
   open_external: (args: any) => ipcRenderer.invoke('native:open-external', args),
 });

src/shared/types.ts

@@ -1,3 +1,26 @@
+export interface DisplayMode {
+  index: number;
+  width: number;
+  height: number;
+  refresh: number;
+  pixel_width: number;
+  pixel_height: number;
+  hidpi: boolean;
+  is_current: boolean;
+}
+
+export interface DisplayInfo {
+  index: number;
+  id: number;
+  is_main: boolean;
+  current_width: number;
+  current_height: number;
+  current_refresh: number;
+  current_pixel_width: number;
+  current_pixel_height: number;
+  modes: DisplayMode[];
+}
+
 export interface SeedConfig {
   event_device_id: string;
   primary_api_base_url: string;
@@ -37,6 +60,8 @@ export interface AetherNativeBridge {
   open_external: (args: {url: string, app?: 'chrome' | 'firefox'}) => Promise<{success: boolean, error?: string}>;
   manage_recording: (args: {action: 'start' | 'stop' | 'status', options?: {fps?: number, audioDeviceId?: string, output?: string}}) => Promise<{success: boolean, isRecording?: boolean, pid?: number, error?: string}>;
   set_display_layout: (args: {mode: 'mirror' | 'extend', configStr?: string | null}) => Promise<{success: boolean, error?: string, stdout?: string, stderr?: string}>;
+  list_display_modes: () => Promise<{success: boolean, displays?: DisplayInfo[], error?: string, raw?: string}>;
+  set_display_mode: (args: {display_index: number, width: number, height: number, refresh_rate?: number, hidpi?: boolean | null}) => Promise<{success: boolean, stdout?: string, stderr?: string, error?: string}>;
   update_app: (args: {source: 'url' | 'file', url?: string, path?: string}) => Promise<{success: boolean, message?: string, downloadedPath?: string, error?: string}>;
 
   // Self-Documentation