## What happened

The Quattro upgrade silently reverted my default terminal from ghostty to foot, and my default browser back to chromium. It reproduced identically on two separate machines, both of which had ghostty explicitly selected beforehand.

Root cause is the `retire` list in `omarchy-upgrade-to-quattro`. For each legacy `~/.config` file it takes the sha256 and, **if the hash matches a known stock default, deletes the file** so a new package-owned system path can take over. Only a hash *mismatch* is treated as a user override worth keeping:

```
# retire: nothing is actually copied. The new package owns the file at the
# system path below (shipped by omarchy-settings), so once the user's
# hash-matched copy in ~/.config is removed, the system path takes effect
# ... User overrides (hash mismatch) are kept active as backups.
# xdg-terminals.list -> /usr/share/xdg-terminal-exec/hyprland-xdg-terminals.list
retire	xdg-terminals.list	7303fa8d1d74eda73cf5fb4c90183a8608c191bb80d7fb9d96ab60f9df06022e
retire	xdg-terminals.list	d035da571a6bfc7d626d4a88846ea86a8adb6f6662f1f8b4abe2330e53ceb71b
```

**A content hash cannot distinguish "never customised" from "deliberately customised to a value that happens to equal a shipped default."**

`omarchy-default-terminal` writes a fixed template with one line swapped:

```bash
cat >~/.config/xdg-terminals.list <<EOF
# Terminal emulator preference order for xdg-terminal-exec
# The first found and valid terminal will be used
$desktop_id
EOF
```

So running the *supported* command, `omarchy default terminal ghostty`, produces a file that is byte-identical to a stock default and therefore hashes onto the retire list. `7303fa8d…` **is** the ghostty file — I confirmed it against my own pre-upgrade backup:

```
$ sha256sum ~/.config/xdg-terminals.list.omarchy-upgrade-to-quattro.20260913003352.bak
7303fa8d1d74eda73cf5fb4c90183a8608c191bb80d7fb9d96ab60f9df06022e
```

Once it was deleted, `/usr/share/xdg-terminal-exec/hyprland-xdg-terminals.list` — installed by `omarchy-settings 4.0.3-1` at the moment of the upgrade, and containing `foot.desktop` — became the winner, because a desktop-specific `<desktop>-xdg-terminals.list` outranks the plain name within each directory and `XDG_CURRENT_DESKTOP=Hyprland`.

`~/.config/mimeapps.list` (`retire … 3b574cef…` → `/usr/share/applications/mimeapps.list`) went the same way, which is where the chromium regression came from.

The effect is that the more faithfully a user followed Omarchy's own documented workflow, the more likely their setting was discarded. Anyone who hand-edited the file kept theirs.

## Expected

A setting chosen through `omarchy default terminal` / `omarchy default browser` survives a major upgrade. At minimum, retiring a file that encodes a user-visible preference should compare the *selected value*, not the file hash.

## Steps to reproduce

1. On Omarchy 3.x, run `omarchy default terminal ghostty` (or alacritty/kitty — the other retire hash is presumably one of those).
2. Do not hand-edit `~/.config/xdg-terminals.list` afterwards.
3. Upgrade to Quattro.
4. Press `Super`+`Return`.

Foot opens. `~/.config/xdg-terminals.list` is gone, with a `.omarchy-upgrade-to-quattro.<timestamp>.bak` beside it.

The mechanism is verifiable on a fixed system without re-upgrading — deleting the user file is exactly the state the retire step leaves behind:

```
$ xdg-terminal-exec --print-id
com.mitchellh.ghostty.desktop
$ rm ~/.config/xdg-terminals.list
$ xdg-terminal-exec --print-id
foot.desktop
```

Binding path, for completeness: `o.bind("SUPER + RETURN", "Terminal", { omarchy = "terminal" })` → `omarchy-launch-terminal` → `xdg-terminal-exec`.

## Suggested fix

Have the retire step consult the *preference* rather than the bytes. For `xdg-terminals.list`, read the entry the user had and, if it is not the new system default, re-write the file (or keep it) instead of deleting it — the value is right there in the file being hashed. The same applies to the browser entries in `mimeapps.list`.

Failing that, dropping `xdg-terminals.list` and `mimeapps.list` from the retire list entirely would be safer than silently reversing a user's choice; a stale user file costs far less than a reverted preference.

A note in the upgrade output naming each retired file would also have made this self-diagnosable — the `.bak` files are the only trace, and their presence is easy to read as "backed up" rather than "your file was deleted and a system default now applies."

## System

- Omarchy 4.0.3-1 (`omarchy-settings 4.0.3-1`)
- Kernel 7.2.4-arch1-2
- AMD Ryzen 9 7900X3D, NVIDIA RTX 5080 + AMD Raphael iGPU
- ghostty 1.3.1-2; foot 1.28.0-1, installed by the upgrade at 2026-09-13T00:34:47-0400
- Also reproduced on a second machine (hybrid Intel/NVIDIA laptop)