## Error Message

```
kwin_wayland[1870]: Failed to delay sleep: Unknown method Inhibit or interface org.freedesktop.login1.Seat.
```

---

## Steps to Reproduce

1. Run KDE Plasma 6.5.2 on Wayland
2. Configure power management with auto-suspend enabled (e.g., 30 minutes)
3. Trigger screen locking or DPMS events
4. Check journal logs

**Actual Result:**
```bash
journalctl -b 0 | grep "Failed to delay sleep"
```

Shows repeated errors:
```
Nov 17 07:26:38 kwin_wayland[1870]: Failed to delay sleep: Unknown method Inhibit or interface org.freedesktop.login1.Seat.
Nov 17 20:32:42 kwin_wayland[1870]: Failed to delay sleep: Unknown method Inhibit or interface org.freedesktop.login1.Seat.
Nov 17 20:44:51 kwin_wayland[1870]: Failed to delay sleep: Unknown method Inhibit or interface org.freedesktop.login1.Seat.
```

**Expected Result:**
kwin_wayland should call `Inhibit` on the Manager interface instead:
```
org.freedesktop.login1 /org/freedesktop/login1 org.freedesktop.login1.Manager.Inhibit
```

---

## Technical Analysis

### D-Bus Interface Verification

Using `busctl introspect` to check available methods:

**Seat interface** (`/org/freedesktop/login1/seat/seat0`):
```bash
busctl introspect org.freedesktop.login1 /org/freedesktop/login1/seat/seat0 org.freedesktop.login1.Seat
```

Methods available:
- ActivateSession
- SwitchTo
- SwitchToNext
- SwitchToPrevious
- Terminate

**NO `Inhibit` method exists on Seat interface.**

**Manager interface** (`/org/freedesktop/login1`):
```bash
busctl introspect org.freedesktop.login1 /org/freedesktop/login1 org.freedesktop.login1.Manager | grep Inhibit
```

Methods available:
- **Inhibit** (signature: ssss -> h)
- ListInhibitors

**The `Inhibit` method EXISTS on Manager interface.**

---

## Root Cause

kwin_wayland is calling:
```
org.freedesktop.login1.Seat.Inhibit
```

But should be calling:
```
org.freedesktop.login1.Manager.Inhibit
```

According to systemd-logind documentation, sleep inhibitors must be created via the Manager interface, not Seat interface.

---

## Impact

**Severity:** Low to Medium

- **User-visible impact:** Error messages in journal logs
- **Functional impact:** kwin cannot create sleep delay inhibitor, preventing proper coordination between screen locking and system suspend
- **Workaround exists:** System remains stable with D-Bus policy configuration (see below)

In some configurations, this can lead to system freezes if D-Bus policy blocks the incorrect method call entirely (returning "policy denied" instead of "unknown method").

---

## Context and History

This issue was discovered during troubleshooting of system freezes during auto-suspend. Initial error was:
```
Failed to delay sleep: Sender is not authorized to send message
```

After adding D-Bus policy to allow `Seat.Inhibit`:
```xml
<allow send_destination="org.freedesktop.login1"
       send_interface="org.freedesktop.login1.Seat"
       send_member="Inhibit"/>
```

The error changed to:
```
Failed to delay sleep: Unknown method Inhibit or interface org.freedesktop.login1.Seat.
```

This confirms kwin is calling the wrong interface.

---

## Expected Fix

kwin_wayland should be updated to call:
```cpp
QDBusInterface("org.freedesktop.login1",
               "/org/freedesktop/login1",
               "org.freedesktop.login1.Manager")
    .call("Inhibit", "sleep", "Screen Locker", "Ensuring screen gets locked", "delay");
```

Instead of calling Inhibit on the Seat object.

---

## Reproducibility

**Always reproducible** on:
- KDE Plasma 6.5.2 (Wayland)
- Arch Linux (up to date as of 2025-11-17)
- systemd 258.2

---