diff --git a/documentation/TODO_AGENTS.md b/documentation/TODO_AGENTS.md
index 8d41db1..3560ec0 100644
--- a/documentation/TODO_AGENTS.md
+++ b/documentation/TODO_AGENTS.md
@@ -66,54 +66,42 @@
 
 ---
 
-## Pending Feature: set_display_layout — displayplacer Per-Device Config
+## set_display_layout — displayplacer Setup & Status (updated 2026-05-20)
 
-**Background (added 2026-05-12, from Svelte-side LaunchProfile work):**
+**Reference:** [jakehilborn/displayplacer](https://github.com/jakehilborn/displayplacer)
 
-The Svelte Events Launcher (`launcher_file_cont.svelte`) now resolves a `LaunchProfile` per file extension and calls `native.set_display_layout({ mode })` before opening a presentation. The underlying handler in `src/main/system_handlers.ts` uses a bundled `displayplacer` macOS binary. The wiring is complete on both ends — but it **silently no-ops on every device** because `displayplacer` requires a per-machine `configStr` (the output of `displayplacer list` on *that specific Mac*) to identify the exact display UUIDs and pixel positions. Without it, `displayplacer` cannot apply any layout.
+**Current state (2026-05-20):**
 
-**What's needed:**
+- ✅ Handler auto-detects displays via `displayplacer list` — no per-device `configStr` required for normal use
+- ✅ Binary lookup order: `resources/bin/displayplacer` (bundled) → `/opt/homebrew/bin/displayplacer` (Apple Silicon Homebrew) → `/usr/local/bin/displayplacer` (Intel Homebrew)
+- ✅ Correct `mirror_of_display:<uuid>` syntax used (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
 
-1. **Capture `configStr` per room Mac.** On each presentation Mac, run:
-   ```
-   displayplacer list
-   ```
-   This prints the current display configuration. Copy the full output for both the "extend" and "mirror" layouts (they differ in which display is primary and how they're positioned).
+**One-time setup on each venue Mac:**
+```bash
+brew install displayplacer
+```
+The binary is not bundled in the Electron build yet. Homebrew installs it to `/opt/homebrew/bin/` (Apple Silicon) or `/usr/local/bin/` (Intel) — both are in the fallback lookup chain.
 
-2. **Store configs in the API.** The Svelte side reads device config from `event_device.data_json`. Store the captured strings there:
-   ```json
-   {
-     "displayplacer_config_extend": "<full configStr for extended layout>",
-     "displayplacer_config_mirror": "<full configStr for mirrored layout>"
-   }
-   ```
-   Admin UI to set these values already exists via the normal event_device edit flow. You can also set them directly via the V3 CRUD API (`PATCH /v3/crud/event_device/{id}/`).
+**Bundling the binary (future):**
+To ship displayplacer inside the `.app` bundle without requiring Homebrew on venue Macs:
+1. Copy the `displayplacer` binary to `resources/bin/displayplacer`
+2. Mark it executable: `chmod +x resources/bin/displayplacer`
+3. Add to `package.json` `extraResources` so `@electron/packager` includes it
 
-3. ✅ **`set_display_layout` in `src/main/system_handlers.ts` already accepts `configStr`.** Handler signature is `{ mode, configStr }` and uses it correctly — no change needed.
+**Optional per-device override (manual tuning):**
+For rooms where auto-detection produces the wrong result, store the raw configStr in `event_device.data_json`:
+```json
+{
+  "displayplacer_config_extend": "<output of displayplacer list in extended layout>",
+  "displayplacer_config_mirror": "<output of displayplacer list in mirrored layout>"
+}
+```
+The handler accepts `configStr` and uses it directly, bypassing auto-detection. Pass it from the Svelte call site if needed.
 
-4. ✅ **Electron relay (`src/preload/index.ts`) already forwards `configStr`** — args passed as-is. `AetherNativeBridge` type in `src/shared/types.ts` updated to include `set_display_layout` with correct signature (2026-05-12).
-
-5. **Pass `configStr` from Svelte.** The Svelte call site in `launcher_file_cont.svelte` (Step 3 in `handle_open_file`) currently calls:
-   ```ts
-   await native.set_display_layout({ mode: profile.display_mode }).catch(() => {});
-   ```
-   It needs to be updated to thread `configStr` from `$ae_loc.native_device.data_json`:
-   ```ts
-   const cfg_key = profile.display_mode === 'mirror'
-       ? 'displayplacer_config_mirror'
-       : 'displayplacer_config_extend';
-   const configStr = ($ae_loc as any).native_device?.data_json?.[cfg_key] ?? null;
-   await native.set_display_layout({ mode: profile.display_mode, configStr }).catch(() => {});
-   ```
-
-**Contract already in place (Svelte side — no action needed):**
-- `$ae_loc.native_device` is the `event_device` object loaded during native app bootstrap
-- `data_json` is an open JSON field on that object
-- `handle_open_file()` already calls `set_display_layout` at the right point — it just needs the configStr threaded through
-
-**Resources:**
-- displayplacer GitHub (usage + examples): https://github.com/jakehilborn/displayplacer
-- `displayplacer list` — prints current layout as a re-runnable config string
-- `displayplacer <configStr>` — applies layout; the configStr from `list` is what you pass back
-- Current Electron handler: `src/main/system_handlers.ts` — find the `set_display_layout` IPC handler
-- Svelte call site: `src/routes/events/[event_id]/(launcher)/launcher_file_cont.svelte` — Step 3 comment in `handle_open_file()`
+**displayplacer quick reference:**
+- `displayplacer list` — prints current display info and a ready-to-run config string at the bottom
+- `displayplacer "<display_string>" "<display_string>"` — applies layout
+- Mirror syntax: add `mirror_of_display:<primary_uuid>` to the secondary display string
+- Extend syntax: set `origin:(<x>,0)` with non-overlapping x offsets per display
diff --git a/src/main/system_handlers.ts b/src/main/system_handlers.ts
index 13cf5ce..42fc707 100644
--- a/src/main/system_handlers.ts
+++ b/src/main/system_handlers.ts
@@ -325,9 +325,16 @@ export function registerSystemHandlers() {
   ipcMain.handle('native:set-display-layout', async (event, { mode, configStr }) => {
     if (os.platform() !== 'darwin') return { success: false, error: 'Display control only supported on macOS' };
 
-    const binPath = app.isPackaged
-      ? path.join(process.resourcesPath, 'bin', 'displayplacer')
-      : path.join(__dirname, '../../resources/bin/displayplacer');
+    // Try bundled binary first; fall back to common Homebrew/system locations.
+    // Install on a dev/venue Mac via: brew install displayplacer
+    const _bin_candidates = 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.
     if (configStr) {
@@ -359,18 +366,18 @@ export function registerSystemHandlers() {
       }
       const primary_id = primary_id_match[1];
 
-      // Primary display unchanged; secondary display(s) get mirror:<primary_id>.
+      // Primary display unchanged; secondary display(s) get mirror_of_display:<primary_id>.
       const mirror_args = display_strings.map((s, i) => {
         if (i === 0) return `"${s}"`;
-        const without_existing_mirror = s.replace(/\s*mirror:\S+/g, '').trim();
-        return `"${without_existing_mirror} mirror:${primary_id}"`;
+        const without_existing_mirror = s.replace(/\s*mirror_of_display:\S+/g, '').trim();
+        return `"${without_existing_mirror} mirror_of_display:${primary_id}"`;
       }).join(' ');
 
       return await runExec(`"${binPath}" ${mirror_args}`);
     }
 
     if (mode === 'extend') {
-      const any_mirrored = display_strings.some(s => /\bmirror:\S+/.test(s));
+      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(' ')}`);
@@ -379,7 +386,7 @@ export function registerSystemHandlers() {
       // 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:\S+/g, '').trim();
+        const without_mirror = s.replace(/\s*mirror_of_display:\S+/g, '').trim();
         const res_match = without_mirror.match(/\bres:(\d+)x\d+/);
         const width = res_match ? parseInt(res_match[1]) : 1920;
         const updated = without_mirror.replace(/\borigin:\([^)]+\)/, `origin:(${x_offset},0)`);