---
description: >-
  Replace SDDM (Qt-based graphical display manager) with greetd + tuigreet
  for a minimal, Wayland-first login experience with zero heavy GUI dependencies.
status: accepted
date: 2026-05-20
replaces: SDDM as display-manager.service
---

# 0003: SDDM to greetd Migration

## Context

The workstation uses Hyprland as the primary Wayland compositor. SDDM was
pulled in as the display manager with significant Qt dependencies (~50+
transitive packages). For a single-user dev workstation running Hyprland,
this is unnecessary overhead — heavy, slow-booting, and over-engineered for
the use case.

SDDM provides: graphical login prompt, session selection, PAM authentication.
All three can be achieved with far lighter tools.

## Decision

Migrate from SDDM to greetd + tuigreet.

- **greetd**: minimal display manager daemon, designed for Wayland first-class.
- **tuigreet**: TUI greeter with time display, user remembering, session
  discovery from `/usr/share/wayland-sessions/` and `/usr/share/xsessions/`.

### What changed

| Before | After |
|--------|-------|
| sddm.service (display-manager) | greetd.service (display-manager) |
| Qt5/Qt6 dependency chain | greetd + greetd-tuigreet (3 packages, 4.9MB) |
| /etc/sddm.conf | /etc/greetd/config.toml |
| Graphical login screen | Text-based TUI login screen |
| Heavy PAM surface | Standard PAM chain (system-local-login) |

### Ansible changes

- Added `greetd` role: installs packages, configures config.toml from template,
  enables greetd as display-manager.service
- Hyprland task renamed: "register session in SDDM" -> "register Wayland session
  desktop entry" (no functional change, just accurate naming)
- vars/main.yml: added `display_manager_package`, `display_manager_greeter`,
  `display_manager_config` variables

### Configuration

```toml
[terminal]
vt = 1
[default_session]
command = "tuigreet --time --remember --asterisks --cmd Hyprland"
user = "greeter"
```

### Rationale

1. **Wayland-native**: greetd handles Wayland sessions cleanly without X
   compatibility layers
2. **Minimal**: 3 packages vs Qt dependency chain; <5MB vs ~500MB
3. **Maintained**: Rust codebase, clean TOML config, Arch repos (no AUR)
4. **AI-agent friendly**: TOML config is trivially parseable/modifiable;
   clean systemd service with structured journalctl output
5. **Simplicity principle**: maximizes work not done

## Consequences

### Positive

- Faster boot (no Qt/Xorg init)
- Smaller attack surface
- Less disk usage
- No Qt dependencies to maintain
- Clean systemd service management

### Negative

- No graphical login (only a limitation if multi-user GUI switching is needed)
- SDDM themes not available (not a requirement for this workstation)
- Tuigreet has fewer visual customization options

### Migration path back

```bash
sudo systemctl disable greetd
sudo systemctl enable sddm
sudo ln -sf /usr/lib/systemd/system/sddm.service /etc/systemd/system/display-manager.service
```

Reversible with zero data loss — the hyprland.desktop session entry is
unchanged and works with both DMs.