# Lid Automation with Suspend/Resume

## Overview

Automated lid handling system that intelligently manages displays and power states based on whether external monitors are connected. Provides seamless docking/undocking experience with proper suspend/resume support.

## Requirements Met

Based on `Lid-Functionality.md` specifications:

- ✅ **Lid closed + external monitors** → Laptop screen turns off, external monitors stay active
- ✅ **Lid closed + no external monitors** → System suspends to sleep
- ✅ **Lid opens from sleep** → System resumes and restores monitors
- ✅ **Lid opens + external monitors** → Three-monitor mode (2 external + laptop)
- ✅ **Dock disconnected** → Automatically switches to mobile-only mode
- ✅ **Dock connected** → Auto-detects and enables external monitors
- ✅ **Waybar restart** → Automatically restarts on monitor configuration changes
- ✅ **Multi-location support** → Handles different monitor configurations

## Architecture

The system consists of three components:

```
ACPI Event (lid open/close)
    ↓
/etc/acpi/lid.sh (ACPI handler)
    ↓
/usr/local/bin/lid-handler.sh (Decision logic)
    ↓
    ├→ External monitors present → Monitor reconfiguration
    └→ No external monitors → System suspend
                                    ↓
                        /lib/elogind/system-sleep/hyprland-resume
                                    ↓
                        Monitor reconfiguration on wake
```

## Components

### 1. ACPI Lid Event Handler

**File**: `/etc/acpi/lid.sh`

**Purpose**: Receives lid open/close events from ACPI daemon

**Function**: Minimal event handler that delegates to the comprehensive lid handler without blocking acpid

```bash
#!/bin/bash
# Simply delegate to comprehensive handler
/usr/local/bin/lid-handler.sh &
exit 0
```

**Why this design:**
- ACPI handlers should return quickly
- Running handler in background prevents blocking acpid
- Keeps ACPI config simple and maintainable

### 2. Comprehensive Lid Handler

**File**: `/usr/local/bin/lid-handler.sh`

**Purpose**: Intelligent decision-making for lid events

**Logic Flow:**

1. **Detect lid state** from `/proc/acpi/button/lid/*/state`
2. **Check for Hyprland** and set up environment
3. **Count external monitors** using `hyprctl monitors`
4. **Make decision:**

   **If lid is CLOSED:**
   - External monitors present → Disable laptop screen only
   - No external monitors → Trigger suspend via `loginctl suspend`

   **If lid is OPEN:**
   - Reconfigure all monitors (handled by monitor-setup.sh)

**Key Features:**
- Properly sets Hyprland environment variables for `hyprctl` to work
- Logs all actions to `/tmp/lid-handler.log`
- Uses `loginctl suspend` (elogind) for proper suspend handling
- Non-blocking execution

**Environment Setup:**
```bash
export HYPRLAND_INSTANCE_SIGNATURE=$(ls -t /tmp/hypr/ | head -n1)
export XDG_RUNTIME_DIR="/run/user/$(id -u)"
export WAYLAND_DISPLAY="wayland-0"
```

### 3. elogind Resume Hook

**File**: `/lib/elogind/system-sleep/hyprland-resume`

**Purpose**: Restores monitor configuration after waking from suspend

**Execution**: Automatically called by elogind with two arguments:
- `$1 = "pre"` before suspend, `"post"` after resume
- `$2 = "suspend"`, `"hibernate"`, or `"hybrid-sleep"`

**On Resume (post):**
1. Wait 2 seconds for system to stabilize
2. Find user running Hyprland
3. Execute monitor-setup.sh as that user
4. Log all actions

**Why this is needed:**
- Monitors may disconnect/reconnect during suspend
- DisplayLink dock needs re-initialization after resume
- Waybar needs restart to update status bar for new monitor layout

**Logs**: `/tmp/elogind-sleep.log`

### 4. Monitor Setup Script

**File**: `/home/alexander/.config/hypr/scripts/monitor-setup.sh`

**Purpose**: Central script for all monitor configuration

**Called by:**
- Lid handler (when lid state changes)
- Resume hook (when waking from suspend)
- DisplayLink hotplug (when dock connects/disconnects)

**Already implemented** and working correctly.

## Installation

All scripts are prepared in `/tmp/`. To install:

```bash
su -
/tmp/install-lid-automation.sh
exit
```

**What the installer does:**
1. Copies lid handler to `/usr/local/bin/`
2. Creates elogind sleep hook directory if needed
3. Installs resume hook in `/lib/elogind/system-sleep/`
4. Replaces ACPI lid handler in `/etc/acpi/lid.sh`
5. Restarts acpid service to activate changes

## Testing

### Test 1: Lid Close with External Monitors

**Procedure:**
1. Connect USB-C dock with external monitors
2. Verify external monitors are working
3. Close laptop lid

**Expected Result:**
- Laptop screen turns off immediately
- External monitors continue working
- No system suspend

**Verify:**
```bash
tail -f /tmp/lid-handler.log
```
Should show: "External monitors detected" and "Disable laptop screen"

### Test 2: Lid Close without External Monitors

**Procedure:**
1. Disconnect USB-C dock
2. Verify only laptop screen is active
3. Close laptop lid

**Expected Result:**
- System suspends within 1 second
- Power LED should blink (suspend indicator)

**Verify:**
After waking, check logs:
```bash
tail /tmp/lid-handler.log
```
Should show: "No external monitors" and "suspending system"

### Test 3: Resume from Suspend

**Procedure:**
1. With laptop suspended (from Test 2)
2. Open laptop lid

**Expected Result:**
- System wakes immediately
- Laptop screen turns on
- Login prompt appears
- Monitors restore to correct configuration

**Verify:**
```bash
tail /tmp/elogind-sleep.log
```
Should show: "Waking from sleep" and "Monitor reconfiguration triggered"

### Test 4: Three-Monitor Mode

**Procedure:**
1. Connect USB-C dock with external monitors
2. Open laptop lid (if closed)

**Expected Result:**
- Two external monitors: 2560x1440@60Hz side-by-side at top
- Laptop monitor: 2880x1800@120Hz centered below
- All three monitors active simultaneously

**Verify:**
```bash
hyprctl monitors
```
Should show 3 active monitors: eDP-1, DVI-I-1, DVI-I-2

### Test 5: Dock Hotplug

**Procedure:**
1. With laptop lid open, disconnect USB-C dock
2. Wait 2-3 seconds
3. Reconnect USB-C dock

**Expected Result:**
- On disconnect: Switches to laptop-only mode
- On reconnect: External monitors appear and configure automatically
- Waybar restarts on each change

**Verify:**
```bash
tail -f /tmp/displaylink-hotplug.log
```

## Troubleshooting

### Lid close doesn't suspend

**Check:**
```bash
cat /etc/elogind/logind.conf | grep HandleLidSwitch
```

Should show:
```
HandleLidSwitch=ignore
HandleLidSwitchExternalPower=ignore
HandleLidSwitchDocked=ignore
```

Our script handles lid logic, not elogind. This is correct.

**Test suspend manually:**
```bash
loginctl suspend
```

If this doesn't work, check:
```bash
cat /sys/power/state
```
Should include `mem` or `s2idle`.

### Monitors don't restore after resume

**Check logs:**
```bash
tail -20 /tmp/elogind-sleep.log
tail -20 /tmp/hyprland-monitor-setup.log
```

**Common issues:**
- DisplayLink dock needs 2-3 seconds to re-initialize after resume
- Increase sleep time in resume hook if needed

**Manual test:**
After resume, run:
```bash
~/.config/hypr/scripts/monitor-setup.sh
```

### ACPI lid events not triggering

**Check acpid is running:**
```bash
rc-status | grep acpid
```

**Test ACPI events:**
```bash
# Clear log
> /tmp/lid-handler.log

# Close lid, wait, open lid

# Check log
cat /tmp/lid-handler.log
```

If no entries, check ACPI event:
```bash
acpi_listen
# Close and open lid - should see events
```

## Logs

All components log their actions:

| Log File | What It Contains |
|----------|------------------|
| `/tmp/lid-handler.log` | Lid event decisions and actions |
| `/tmp/elogind-sleep.log` | Suspend/resume events |
| `/tmp/hyprland-monitor-setup.log` | Monitor configuration details |
| `/tmp/displaylink-hotplug.log` | Dock connection/disconnection |

**Monitor all logs simultaneously:**
```bash
tail -f /tmp/lid-handler.log /tmp/elogind-sleep.log /tmp/hyprland-monitor-setup.log
```

## Configuration

### Single User System

The system is designed for single-user operation (alexander). The scripts automatically detect the user running Hyprland.

### Different Monitor Configurations

The monitor setup script uses `preferred` resolution and auto-positioning. To support different locations (work/home) with different monitors:

**Option 1: Let it auto-configure** (current approach)
- Works for most setups
- Monitors use their preferred resolution

**Option 2: Create location profiles** (future enhancement)
- Detect location by monitor serial numbers
- Load specific configuration per location
- Requires extending monitor-setup.sh

## Dependencies

- **elogind**: Session management and suspend/resume
- **acpid**: ACPI event handling
- **hyprland**: Window manager with hyprctl
- **jq**: JSON parsing for monitor queries
- **loginctl**: elogind control utility

All dependencies are already installed and working.

## Files Modified/Created

| File | Action | Purpose |
|------|--------|---------|
| `/usr/local/bin/lid-handler.sh` | Created | Main lid event logic |
| `/lib/elogind/system-sleep/hyprland-resume` | Created | Resume hook |
| `/etc/acpi/lid.sh` | Replaced | ACPI event entry point |
| `/home/alexander/.config/hypr/scripts/monitor-setup.sh` | Already exists | Monitor configuration |

## Design Decisions

### Why not let elogind handle lid events?

**Problem**: elogind's lid handling is all-or-nothing:
- `HandleLidSwitch=suspend` → Always suspends (even with external monitors)
- `HandleLidSwitch=ignore` → Never suspends (manual suspend only)

**Solution**: Custom logic that considers external monitor state.

### Why use loginctl suspend instead of writing to /sys/power/state?

**Reasons:**
- elogind handles pre-suspend tasks (session locking, service notifications)
- Proper resume hook execution
- Better integration with session management
- Logs in journal/syslog

### Why run handler in background from ACPI?

**Reasons:**
- ACPI handlers should return quickly (< 1 second)
- Suspend takes time, would block acpid
- Other ACPI events (power button, dock) need to be handled concurrently

### Why wait 2 seconds on resume?

**Reasons:**
- DisplayLink USB devices need time to re-enumerate
- Kernel drivers need to re-initialize
- Too fast = monitors not detected yet
- Too slow = user sees blank screens longer

**Tunable**: Adjust sleep time in `/lib/elogind/system-sleep/hyprland-resume` if needed.

## Future Enhancements

**1. Monitor Configuration Profiles**
- Detect location by monitor serial numbers
- Load specific layouts per location
- Store in `~/.config/hypr/monitor-profiles/`

**2. Lock Screen on Suspend**
- Integrate with swaylock or gtklock
- Lock before suspend, unlock on resume

**3. Notification on Dock Connect/Disconnect**
- Use mako to show notifications
- "Dock connected: 2 monitors"
- "Switched to mobile mode"

**4. Faster Resume**
- Pre-load DisplayLink configuration
- Reduce sleep time by detecting device readiness

**5. Hibernation Support**
- Similar to suspend but saves to disk
- Requires swap configuration
- Useful for extended battery life

## References

- elogind documentation: `/usr/share/doc/elogind-*/`
- ACPI specification: https://www.kernel.org/doc/Documentation/acpi/
- Original requirements: `Lid-Functionality.md`
- Monitor configuration: `Monitor-Dock-via-DisplayLink.md`