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+# Settings Panel & New Session Design
+
+## Goal
+
+Add a Settings panel and New Session feature to muxplex, removing the command palette (now redundant with the sidebar).
+
+## Background
+
+The command palette was the original mechanism for session switching, but the sidebar + hover preview + click-to-navigate flow now covers the same functionality. The header space freed by removing the palette is better used for settings access and session creation — two features muxplex currently lacks.
+
+Settings need to live in two places: per-device preferences (font size, notifications) in localStorage, and per-user configuration (session defaults, templates) in a server-side file that persists across devices.
+
+## Approach
+
+- **Settings** as a modal dialog (desktop) / bottom sheet (mobile), triggered by a gear icon in the header. Controls apply immediately with debounced persistence — no Save button.
+- **New Session** as an inline name input that replaces the `+` button on click. A configurable command template in settings controls what actually runs on the server.
+- **Command palette removal** — delete all palette HTML, CSS, and JS.
+
+---
+
+## Architecture
+
+### Settings Access
+
+Gear icon (⚙) in the header, right side, next to a `+` (new session) button and connection status indicator. Same position in both dashboard and expanded terminal views.
+
+Keyboard shortcut: `,` (comma, VS Code convention).
+
+### Desktop Layout (≥600px)
+
+Centered modal dialog — same pattern as the now-removed command palette (backdrop, escape-to-close, centered panel):
+- Width: `min(600px, 90vw)`
+- Height: `min(480px, 80vh)`
+- Left tab list: 140px fixed width
+- Active tab: `color: var(--accent)` with 2px left border in `var(--accent)`
+
+Tabs: **Display**, **Sessions**, **Notifications**, **New Session**.
+
+### Mobile Layout (<600px)
+
+Bottom half-sheet (slides up from bottom, drag-to-dismiss downward):
+- Same gear icon trigger
+- 48px minimum touch targets for all controls
+- Dim overlay behind
+- Max height ~85vh
+
+### Storage Split
+
+**localStorage (per-device):** Font size, grid columns, hover preview delay, bell sound, desktop notification permission.
+
+**Server (`~/.config/muxplex/settings.json`):** Default session, sort order, hidden sessions, window-size largest, auto-open created sessions, new session command template.
+
+No sync between the two. If localStorage is cleared, the user gets defaults. Server settings persist across devices via the API.
+
+### Controls Behavior
+
+All controls apply immediately — no Save button. Each change debounces 500ms then persists (PATCH to server or localStorage write). A subtle toast confirms the save. This matches developer tool conventions (VS Code, terminal settings).
+
+---
+
+## Components
+
+### API Endpoints
+
+| Method | Path | Description |
+|--------|------|-------------|
+| `GET` | `/api/settings` | Returns server-side `settings.json` contents |
+| `PATCH` | `/api/settings` | Partial update — merges single-field saves |
+| `POST` | `/api/sessions` | Creates a new session (`{"name": "my-project"}`) |
+
+### Server-Side Settings File
+
+`~/.config/muxplex/settings.json`:
+
+```json
+{
+  "default_session": null,
+  "sort_order": "manual",
+  "hidden_sessions": [],
+  "window_size_largest": false,
+  "auto_open_created": true,
+  "new_session_template": "tmux new-session -d -s {name}"
+}
+```
+
+### localStorage Key
+
+`muxplex.display` — single JSON blob:
+
+```json
+{
+  "fontSize": 14,
+  "hoverPreviewDelay": 1500,
+  "gridColumns": "auto",
+  "bellSound": false,
+  "notificationPermission": "default"
+}
+```
+
+---
+
+## Settings Categories & Fields
+
+### Display Tab (localStorage)
+
+| Field | Control | Default |
+|---|---|---|
+| Font size | `<select>` (11, 12, 13, 14, 16px) | 14 |
+| Hover preview delay | `<select>` (Off, 1s, 1.5s, 2s, 3s) | 1.5s |
+| Grid columns | `<select>` (Auto, 2, 3, 4) | Auto |
+
+### Sessions Tab (server)
+
+| Field | Control | Default |
+|---|---|---|
+| Default session | `<select>` (None + current session list) | None |
+| Sort order | `<select>` (Manual, Alphabetical, Recent activity) | Manual |
+| Hidden sessions | Checkbox list of session names | None hidden |
+| Auto-set window-size largest | Checkbox | Off |
+| Auto-open created sessions | Checkbox | On |
+
+### Notifications Tab (localStorage)
+
+| Field | Control | Default |
+|---|---|---|
+| Bell sound | Checkbox | Off |
+| Desktop notifications | Button: "Request permission" / status text | Not requested |
+
+### New Session Tab (server)
+
+| Field | Control | Default |
+|---|---|---|
+| Command template | `<textarea>` monospace, 3 rows | `tmux new-session -d -s {name}` |
+| | Helper text: *`{name}` is replaced with the session name* | |
+| | `[ Reset to default ]` button | |
+
+---
+
+## New Session Feature
+
+### Button Placement
+
+- **Dashboard header:** `[+]` button, right side, between wordmark and gear icon. Styled same as gear — `border: 1px solid var(--border)`, `color: var(--text-dim)`.
+- **Expanded view sidebar:** `+ New` sticky footer below session list.
+- **Mobile (<960px):** 56px FAB, bottom-right, 16px from edges. `+` icon. Replaces header button on mobile.
+
+### Creation Flow — Inline Name Input
+
+Click `+` → button transforms into a text input inline in the header. Auto-focus, placeholder "Session name…", Enter to create, Escape to cancel. One field only — everything else comes from the template.
+
+Sidebar footer: same pattern — button becomes input field inline.
+
+### Template Execution
+
+Configured in Settings → New Session tab. Default: `tmux new-session -d -s {name}`. The `{name}` variable is the only substitution — replaced at creation time.
+
+### Backend
+
+`POST /api/sessions` with `{"name": "my-project"}`.
+
+Server reads template from `settings.json`, substitutes `{name}`, executes via subprocess. Returns 200 with `{"name": "..."}`.
+
+**No existence check** — this deliberately handles create-or-reattach patterns (e.g., `amplifier-dev ~/dev/{name}` creates new or reattaches to existing). If the command fails, the session won't appear and the user sees the dashboard unchanged.
+
+### Post-Creation Behavior
+
+1. Show toast: "Session '{name}' created"
+2. Trigger immediate `pollSessions()` refresh
+3. Auto-open the session if "auto-open created sessions" is enabled in settings
+
+---
+
+## Command Palette Removal
+
+Remove the entire command palette:
+- **HTML:** `#command-palette` div + `#palette-trigger` button
+- **CSS:** `.command-palette*`, `.palette-*`
+- **JS:** palette state variables, `openPalette`, `closePalette`, `renderPaletteList`, `highlightPaletteItem`, palette keyboard handler, palette event bindings
+
+The sidebar + hover preview + click-to-navigate already provides the same session switching functionality. The header space freed by removing the `⌘K` button is where the `+` and `⚙` buttons go.
+
+---
+
+## Security
+
+The new session template is a shell command the user writes and the server executes. PAM auth already proves they own the machine — this is equivalent to typing in their own terminal. No command sanitization needed.
+
+---
+
+## Implementation Notes
+
+### Files to Create
+
+- `muxplex/frontend/settings.js` — settings modal/sheet logic, tab switching, field rendering, localStorage + API integration
+- `muxplex/frontend/settings.html` (or inline in `index.html`) — settings dialog markup
+
+### Files to Modify
+
+- `muxplex/frontend/index.html` — remove command palette HTML, add settings dialog HTML, add `+` and `⚙` header buttons
+- `muxplex/frontend/style.css` — remove palette CSS, add settings modal/sheet CSS, add FAB CSS, add inline input CSS
+- `muxplex/frontend/app.js` — remove all palette JS, add settings open/close, add new session creation flow, wire up `+` button and FAB
+- `muxplex/main.py` — add `GET/PATCH /api/settings` endpoints, add `POST /api/sessions` endpoint
+- `muxplex/cli.py` — load `settings.json` at startup for template default
+
+---
+
+## Open Questions
+
+1. Should hidden sessions still be visible with a "hidden" badge, or completely removed from the grid?
+2. Should the new session input validate the name (alphanumeric + dash only) or accept anything tmux accepts?
+3. Should the gear/settings be accessible from the login page (pre-auth) for display preferences? Probably not for v1.