# Atlus — Project Context

## What Is Atlus?

Atlus is a lightweight, web-based desktop environment designed for headless single-board computers (SBCs) such as the Orange Pi, Raspberry Pi, and similar ARM-based Linux systems. It provides a browser-accessible interface that replaces the need for SSH or VNC for everyday system management tasks.

The goal is not to replicate a full desktop environment — it is to provide the *right* tools for managing a headless SBC in a way that feels natural, fast, and accessible from any device on the local network.

---

## Problem Statement

Headless SBCs are increasingly used as always-on servers, astrophotography rigs, NAS boxes, home automation hubs, and more. Current management options are:

- **SSH** — powerful but unfriendly for non-developers and tedious for routine tasks
- **VNC / noVNC** — requires a full desktop environment, heavy, slow, not purpose-built
- **Cockpit / Webmin** — generic server admin tools, not tailored to SBC use cases, complex UI

There is no lightweight, purpose-built web desktop for SBCs that feels like an OS rather than a server admin panel.

---

## Core Philosophy

- **Web-native first** — no X server required for core functionality
- **Purposefully minimal** — only the tools that matter for headless SBC management
- **Locally hosted** — runs entirely on the SBC, no cloud dependency
- **Accessible from anything** — phone, tablet, laptop — any browser on the local network
- **Tiling over floating** — apps open in the center stage, not as draggable windows
- **Extensible** — apps/widgets can be added as plugins

---

## Target Users

- Makers and hobbyists running headless SBCs for specific purposes (astrophotography, NAS, IoT, etc.)
- Home lab users who want lightweight management without full desktop overhead
- Anyone who currently lives in SSH and wishes there was something better

---

## ✅ Finalized Layout — Three-Column Shell

The Atlus UI is a fixed three-column layout inspired by tiling window managers (awesomewm, i3). There are no draggable or floating windows. Everything is tiled, cascaded, or tabbed within the center stage.

```
┌────────┬─────────────────────────────┬────────────────┐
│        │  Stage Tab Bar              │                │
│  Left  ├─────────────────────────────┤  Right Panel   │
│  Dock  │                             │                │
│        │     Center Stage            │  - Hostname    │
│ App    │     (active app view)       │  - Date/Time   │
│ Icons  │                             │  - Network     │
│        │     One app at a time,      │  - CPU/RAM/    │
│ (vert) │     or tiled side-by-side   │    Disk/Temp   │
│        │                             │  - Services    │
│ Gear   ├─────────────────────────────┤    (toggles +  │
│ (foot) │  Layout Controls (tab bar)  │    open → )    │
└────────┴─────────────────────────────┴────────────────┘
```

### Left Dock
- Vertical strip of app launcher icons — no labels, tooltip on hover
- Top: Atlus "A" logo — opens a system menu (shutdown, restart, about)
- Core apps listed in order (configurable in settings)
- Separator line between core apps and plugins
- Bottom: Settings gear icon (always pinned)
- Active app highlighted with accent border/background
- Badge dot on plugin icons when they have status to report (e.g. ASI Bridge syncing)

### Center Stage
- The primary content area — full height, fills remaining width
- One app visible at a time by default
- **Tab bar** at top shows all open apps; click to switch (previous app minimizes)
- **Layout toggle buttons** (top-right of tab bar) switch between:
  - Single pane (full width)
  - Horizontal split (two panes side-by-side, 50/50 default)
  - Vertical split (stacked, stretch goal)
- Each pane has its own macOS-style titlebar (traffic light dots + title)
- When a second app is opened in split mode, it takes the secondary pane

### Right Panel
- Always visible, fixed width (~220px), never replaced by an app
- **Top section:** Hostname, date, time (live), WiFi name + status, Ethernet status
- **Middle section:** Live system stats — CPU %, Memory used/total, Storage %, CPU temp
  - Each stat: compact uppercase label + current value + colored progress bar
  - Colors: green (healthy), amber (moderate), red (high)
- **Bottom section:** Services list
  - Each service: toggle (on/off), name, ↗ open button
  - Toggle maps to `systemctl start/stop`
  - ↗ opens that service's detail/control view in the center stage
  - Services list is configurable per deployment

---

## Architecture Overview

### Backend Daemon
- Language: **Python (FastAPI + asyncio)**
- Runs as a systemd service on boot
- Exposes a REST API and WebSocket endpoint
- Responsibilities:
  - File system access and management
  - Systemd service control (start/stop/restart/status)
  - Process/task enumeration
  - System stats (CPU, RAM, disk, network, temperature) via psutil
  - Notification/event bus (watches logs, mount points, service states)
  - X11 app process spawner (Xvfb + x11vnc per app — Phase 4 only)

### Frontend
- Language: **Vanilla JS + CSS** (no framework — keep it lightweight and portable)
- No build step — served directly as static files by the FastAPI backend
- Communicates via REST for actions, WebSocket for live stat updates
- CSS custom properties for theming
- IBM Plex Mono for system data; Inter for UI chrome

### X11 App Embedding (Phase 4 — Optional/Advanced)
- For GUI apps that require X (e.g., Nextcloud desktop client)
- Each app spawns its own Xvfb virtual framebuffer
- x11vnc streams that framebuffer over WebSocket via noVNC
- Embedded as a pane in the center stage — not a floating window
- Isolated per-app — no shared display, no full desktop environment needed

---

## Built-in Apps (Core)

### ⚙️ System Settings
The unified configuration hub for the SBC. Organized into sections:

- **General** — System name/hostname, date & time (manual or NTP), timezone
- **Users** — User management, password changes, add/remove users
- **Security** — Screen lock timeout, session timeout, auth settings
- **Applications** — Choose which apps appear in the dock; enable/disable on startup
- **Services** — Which systemd services appear in the right panel; autostart configuration
- **Network** — Per-interface settings (WiFi SSID/password, static IP vs DHCP, DNS); shown for all detected interfaces (eth0, wlan0, etc.)
- **Storage / Automount** — USB automount rules, mount point configuration, eject behavior
- **About** — Atlus version, system info, OS details

---

### 📟 Terminal
A fully functional web-based terminal. No restrictions, no simplifications — behaves identically to SSH or a local terminal session. Powered by xterm.js on the frontend and ptyprocess on the backend for a real PTY.

#### Custom On-Screen Keyboard (Critical)
The system keyboard (iOS/Android) is **never triggered**. Atlus uses its own purpose-built on-screen keyboard for all terminal input. This is non-negotiable — the native keyboard is hostile to terminal use (autocorrect, autocapitalize, no Escape, no function keys, unpredictable behavior).

**How it works technically:**
- The xterm.js terminal canvas is focused but never triggers a system keyboard (it is not an `<input>` or `<textarea>`)
- All key input is intercepted via the custom keyboard UI — keys send characters directly to the terminal via `terminal.input(char)` and escape sequences for special keys
- The terminal pane never calls `.focus()` on any element that would summon the system keyboard
- `inputmode="none"` set on any focusable elements within the terminal pane as a belt-and-suspenders measure

**Custom keyboard layout — three rows:**

```
Row 1 (special/modifier):
[ Esc ] [ Tab ] [ Ctrl ] [ Alt ] [ ` ] [ ~ ] [ | ] [ \ ] [ / ]

Row 2 (function keys, scrollable):
[ F1 ] [ F2 ] [ F3 ] [ F4 ] [ F5 ] [ F6 ] [ F7 ] [ F8 ] [ F9 ] [ F10 ] [ F11 ] [ F12 ]

Row 3 (navigation):
[ ↑ ] [ ↓ ] [ ← ] [ → ] [ Home ] [ End ] [ PgUp ] [ PgDn ] [ Del ]
```

**Modifier key behavior:**
- Ctrl, Alt are sticky — tap once to arm, next key sends the combo (e.g. Ctrl → C sends `\x03`)
- Armed modifier keys are visually highlighted
- Double-tap a modifier to lock it (Ctrl+lock for vim, etc.)

**Standard alphanumeric input:**
- A compact QWERTY layout below the special rows handles letter/number/symbol input
- Numbers row across the top of the QWERTY section
- Shift key for capitals — also sticky
- Common terminal symbols promoted to easy reach: `$`, `#`, `>`, `-`, `_`, `.`

**Keyboard can be:**
- Toggled show/hide via a keyboard icon button in the terminal pane titlebar
- Resized (compact vs. full) — compact shows only the special row + QWERTY condensed
- On physical keyboard connected to iPad: custom keyboard hides, physical keys work natively through xterm.js

**Other terminal features:**
- Full color output, cursor control, scrollback
- Resize-aware (terminal resizes with the pane, keyboard height accounted for)
- Copy: long-press selection in terminal → copy action
- Paste: paste button on keyboard toolbar injects clipboard content via `terminal.input()`
- Multiple terminal tabs within the terminal pane (Phase 2)

---

### 🗂 File Manager
Unique dual-pane design. Key characteristics:

- **Single or dual folder view** — toggle between one panel (full width) and two side-by-side panels
- **List view only** — no icon grid; each row shows: icon type indicator, filename, size, modified date, permissions
- **Drag and drop** — files can be dragged between panels or into folders within a panel
- **Sidebar** — shows filesystem tree: home, root, and all detected mounts (USB, SMB, etc.)
- **Features per file/selection:**
  - Preview (text, image, FITS header for astrophotography files)
  - Compress / extract (zip, tar.gz)
  - Copy, move, rename, delete
  - Properties (permissions, owner, size on disk)
- **Mount management** — right-click a mount point to unmount; USB devices show an eject option
- **Path bar** — editable breadcrumb path at the top of each panel
- **No thumbnails** — performance-first; list only

---

### 📊 Task Manager
htop-inspired, but scoped and web-native. Shows:
- Process list: PID, name, CPU %, MEM %, status, user
- Sortable columns
- Kill / signal process action
- Filter to show only Atlus-relevant processes (or toggle to show all)
- Summary bar at top: total CPU, RAM, load average — mirrors the right panel stats but with more detail
- Auto-refreshes every 2 seconds via WebSocket

---

### 🌐 Network Monitor
Per-interface detail view:
- Interface name, MAC, state (up/down)
- IP addresses (IPv4 + IPv6)
- Gateway, DNS servers
- Live throughput (bytes in/out per second)
- For WiFi: SSID, signal strength, frequency band

---

### 🔧 Settings
*(see System Settings above — Settings is the dock entry point into the System Settings app)*

---

### Plugin Apps (Installable)

| App | Dock Icon | Description |
|---|---|---|
| **ASI Bridge** | `🔭` | ASI Air mount status, transfer log, Nextcloud sync, session summary |
| **Log Viewer** | `📝` | Real-time tail of any systemd service log via WebSocket |
| **INDI Control** | *(future)* | INDI server management for astrophotography rigs |

---

## Design Language

### Aesthetic
- Dark, utilitarian, refined — high-end terminal meets modern OS
- Inspired by: awesomewm, macOS terminal, Linear app
- Flat — no gradients, no heavy shadows, no decorative elements

### Typography
- **IBM Plex Mono** — all system data, file paths, IPs, timestamps, terminal output
- **Inter** — UI chrome, labels, app names, navigation
- Two weights only: 400 regular, 500 medium

### Color System
- Background layers (dark → light): `#0d0f14` → `#111318` → `#161b27`
- Borders: `#1e2130` (structural), `#2a2d36` (component-level)
- Text: `#c8ccd8` (primary), `#8891a8` (secondary), `#4a5068` (muted), `#2e3348` (ghost)
- Accent (active/selected): `#6ea6f0`
- Status: `#3ab86a` (ok/green), `#e09a2a` (warning/amber), `#e05a4a` (error/red)

### Motion
- Subtle only: tab switches, service toggle state, stat bar transitions
- Status values update live via WebSocket — no manual refresh needed

---

## ✅ Touch-First Design — Primary Target: iPad & Tablets

Atlus is **touch-first**. Desktop mouse/keyboard is secondary. Every interaction must be comfortable with a finger on a tablet screen. This affects every component.

### Touch Target Sizing
- **Minimum tap target: 48×48px** for all interactive elements (Apple HIG / Material guidelines)
- Dock icons: 56×56px minimum hit area
- File rows: minimum 48px tall
- Settings rows: minimum 48px tall
- Service toggles: at least 44px tall hit area (even if visually smaller)
- Tab bar items: minimum 44px tall
- All buttons: minimum 44px tall

### No Hover Dependency
- **No tooltips as primary labels** — dock icons must show a label below the icon (not on hover)
- No hover-only states for anything critical
- All context menus triggered by **long-press**, not right-click
- Hover styles may exist as a progressive enhancement for mouse users, but never as the only way to discover functionality

### Gesture Support
- **Swipe left/right** on the center stage to switch between open apps (like iOS app switching)
- **Swipe right from left edge** to reveal/toggle the dock on smaller screens
- **Swipe left from right edge** to reveal/toggle the right panel on smaller screens
- **Long-press** on files for context menu (cut, copy, rename, delete, compress, properties)
- **Long-press** on dock icon for app options (remove from dock, move)
- **Pull down** on file list to refresh directory
- **Pinch to zoom** in terminal and file preview — browser native

### Layout Adaptations for Touch

#### Landscape (primary tablet orientation):
- Three-column layout as designed — dock (72px wide), stage (flex), right panel (240px)
- Dock shows icon + label underneath (not tooltip)
- All rows/items generously spaced

#### Portrait / Narrow screens:
- Dock collapses to a slide-in drawer (swipe from left or tap hamburger)
- Right panel collapses to a slide-in drawer (swipe from right or tap info button in tab bar)
- Center stage goes full-width
- Tab bar remains visible at top

#### Phone (stretch goal, not v1):
- Bottom tab bar replaces left dock
- Right panel accessible via bottom sheet

### File Manager — Touch Adaptations
- Row height: 52px minimum
- Drag and drop uses **touch drag** (touchstart/touchmove/touchend events) not mouse drag
- Selection via long-press + drag, or tap checkbox mode
- Checkbox mode: tap a file to enter selection mode, then tap others to multi-select
- Context menu on long-press: open, preview, copy, move, rename, compress, delete
- No right-click context menu (or: right-click works as fallback for mouse users)

### Terminal — Touch Adaptations
- Software keyboard appears automatically on tap
- Toolbar of common keys above the software keyboard: Escape, Tab, Ctrl, arrow keys, pipe, tilde
- Pinch to adjust font size
- Two-finger scroll for scrollback

### Settings — Touch Adaptations
- All form rows 52px+ tall
- Toggle switches 51×31px (standard iOS-style)
- Sidebar nav items 48px tall minimum
- Save/cancel buttons large and thumb-reachable (bottom of content, full-width or right-aligned with generous padding)

### Right Panel — Touch Adaptations
- Service rows 52px tall — the toggle and ↗ button are both easy targets
- On narrow screens: collapses, accessible via swipe or button

### General Touch Rules
- No double-click interactions — everything single tap or long-press
- Scroll areas must be `-webkit-overflow-scrolling: touch` (momentum scrolling)
- `touch-action` set appropriately on draggable items
- Input fields: `font-size: 16px` minimum to prevent iOS auto-zoom on focus
- Avoid `position: fixed` where possible — use `position: sticky` for headers/toolbars
- All modals/dialogs centered and thumb-reachable, not tiny desktop-style popups

---

## Astrophotography Reference Deployment

The initial real-world deployment target:

```
[ASI Air]  ──ethernet──▶  [Orange Pi 5 Max / Atlus]  ──nextcloud──▶  [Home Server]
192.168.10.120              192.168.10.121 (eth to ASI Air)
                            192.168.1.121  (wifi to home network)
```

The **ASI Bridge** plugin panel shows:
- ASI Air SMB mount status (connected / disconnected / error)
- Nextcloud client sync status (idle / syncing / error)
- Live transfer log (filename, size, timestamp, sync result)
- Session summary (frames captured tonight, total GB transferred)
- Quick actions: remount share, restart sync service, clear log

---

## Tech Stack

| Component | Technology |
|---|---|
| Backend | Python 3.11+, FastAPI, asyncio, uvicorn |
| WebSockets | FastAPI WebSocket |
| System stats | psutil |
| Terminal | xterm.js (frontend) + ptyprocess (backend) |
| File ops | Python pathlib / os |
| Service mgmt | subprocess + systemctl |
| X11 embedding | Xvfb + x11vnc + noVNC (Phase 4 only) |
| Frontend | Vanilla JS, CSS custom properties, no build step |
| Fonts | IBM Plex Mono + Inter (Google Fonts CDN or self-hosted) |
| Packaging | Single systemd service + `install.sh` bootstrap script |
| Target OS | Debian/Ubuntu ARM64 (DietPi, Armbian, Raspberry Pi OS) |

---

## Project Phases

### Phase 1 — Core Shell *(start here)*
- [ ] Repo and project structure setup
- [ ] FastAPI backend — `/api/stats` endpoint (CPU, RAM, disk, temp, network IPs)
- [ ] WebSocket endpoint — push live stats every 2s
- [ ] Static frontend served by FastAPI
- [ ] Three-column shell layout (dock, stage, right panel) — HTML/CSS skeleton
- [ ] Right panel wired to live WebSocket stats + clock
- [ ] Left dock with app icons and active state
- [ ] Terminal app — xterm.js frontend + ptyprocess PTY backend
- [ ] App switching — clicking dock icon loads app into center stage

### Phase 2 — File Manager + Service Control
- [ ] File Manager — directory listing, navigate, breadcrumb path, sidebar mounts
- [ ] Service Manager — list systemd units, start/stop/restart via API
- [ ] Right panel service toggles wired to real systemctl calls
- [ ] Log Viewer — real-time tail of service logs via WebSocket stream
- [ ] Split pane layout — two apps tiled side by side

### Phase 3 — Plugin System + ASI Bridge
- [ ] Plugin architecture — self-contained module (backend route + frontend panel JS)
- [ ] ASI Bridge plugin — mount watcher, transfer log, Nextcloud sync status
- [ ] Settings app — configure dock items, services list, hostname display

### Phase 4 — X11 App Embedding *(advanced)*
- [ ] Xvfb process spawner via API call
- [ ] x11vnc per-app streaming to WebSocket
- [ ] noVNC embedded as a center stage pane
- [ ] Nextcloud Qt client embedded as live X11 panel

---

## ✅ Finalized Project Decisions

| Decision | Answer |
|---|---|
| **Project type** | Single monorepo — frontend served by FastAPI backend |
| **Framing** | Full desktop environment — not a server admin panel |
| **Authentication** | Username + password (session token after login) |
| **Default port** | 7779 |
| **Installation** | `curl \| bash` installer script |
| **License** | GPL |
| **Theming** | Dark only for v1 — light mode planned, CSS variables structured for it from day one |
| **Target OS** | DietPi (Debian ARM64) — installer targets DietPi, Armbian, Ubuntu Server as fallbacks |
| **Terminal sessions** | Multiple — tabbed terminals within the terminal pane |
| **Boot / login** | Branded login/boot screen before the desktop loads |
| **Filesystem access** | Full — same as any desktop environment |
| **Terminal user** | Runs as the logged-in system user |
| **Multiple clients** | Yes — multiple browsers/devices can connect simultaneously, all receive live WebSocket updates |
| **File operations** | Confirm destructive actions only (delete, overwrite) |
| **Service detection** | Auto-detect all systemd services — user manages visibility in Settings |
| **ASI Bridge when disconnected** | Show disconnected badge — still openable, shows a disconnected state screen |
| **Plugin (ASI Bridge)** | Built-in from day one, bundled with Atlus core |
| **Dock order** | Hard-coded for v1, configurable in Settings v2 |
| **Right panel width** | Fixed 240px for v1 |

---

## Project Structure (Monorepo)

```
atlus/
├── README.md
├── LICENSE                    # GPL
├── install.sh                 # curl | bash installer
├── atlus.service              # systemd unit file template
│
├── backend/
│   ├── main.py                # FastAPI app entry point
│   ├── config.py              # Config, paths, constants
│   ├── auth.py                # Username/password auth, session tokens
│   ├── routers/
│   │   ├── stats.py           # /api/stats — CPU, RAM, disk, temp, network
│   │   ├── files.py           # /api/files — filesystem operations
│   │   ├── services.py        # /api/services — systemd management
│   │   ├── processes.py       # /api/processes — task manager
│   │   ├── terminal.py        # /api/terminal — PTY websocket
│   │   ├── settings.py        # /api/settings — read/write config
│   │   └── plugins/
│   │       └── asi_bridge.py  # ASI Air bridge plugin routes
│   ├── ws/
│   │   └── manager.py         # WebSocket connection manager (multi-client broadcast)
│   └── requirements.txt
│
├── frontend/
│   ├── index.html             # Login/boot screen
│   ├── desktop.html           # Main desktop shell
│   ├── css/
│   │   ├── variables.css      # CSS custom properties (colors, spacing, typography)
│   │   ├── shell.css          # Three-column layout
│   │   ├── dock.css
│   │   ├── panel.css
│   │   ├── stage.css
│   │   ├── keyboard.css       # Custom on-screen keyboard
│   │   └── apps/
│   │       ├── terminal.css
│   │       ├── files.css
│   │       ├── settings.css
│   │       └── tasks.css
│   ├── js/
│   │   ├── atlus.js           # Core shell, app switching, WebSocket client
│   │   ├── auth.js            # Login screen logic
│   │   ├── keyboard.js        # Custom on-screen keyboard
│   │   └── apps/
│   │       ├── terminal.js    # xterm.js + PTY integration
│   │       ├── files.js       # File manager
│   │       ├── settings.js    # Settings app
│   │       ├── tasks.js       # Task manager
│   │       ├── services.js    # Service manager
│   │       └── asi_bridge.js  # ASI Bridge plugin panel
│   └── assets/
│       └── atlus-logo.svg
│
└── plugins/                   # Future third-party plugins live here
```

---

## Open Questions (Deferred — Not Blocking v1)

- **Portrait collapse behavior**: Slide-in drawers vs. bottom tab bar — decide when building responsive CSS
- **Terminal keyboard quick-key row**: Exact key selection — decide during keyboard build

---

*Last updated: 2026-03-13*
*Project status: Planning complete ✅ — all decisions finalized — ready to build Phase 1*