# Clock calendar popup misaligned by one day after DST spring-forward (America/Santiago)

## System details

- Omarchy: 4.0.3-1
- Quickshell: 0.3.1 (Arch package)
- Kernel: 7.2.3-arch1-3
- Timezone: America/Santiago (DST active, -03)
- Widget: `omarchy.clock` (stock bar widget / calendar panel)

## What's wrong

In a timezone where DST starts at midnight — Chile's DST began **Sunday 2026-09-06 at 24:00**, so local midnight of Sep 6 does not exist — the clock panel's month grid is shifted one column to the right for the rest of that month. September 10, 2026 (a Thursday) renders in the **FRI** column, and the bar simultaneously (and correctly) shows "Thursday".

Screenshot shows the giveaway: the first week row reads `31 1 2 3 4 5 5` — the **5 is duplicated and the 6 is missing**. Every subsequent cell is then one weekday off, while the today-highlight (keyed by date, not column) lands on "10 under FRI".

## Root cause

`plugins/panels/clock/Model.js`, `monthGrid()` steps a day cursor forward with:

```js
var cursor = new Date(year, month, 1 - leading)
...
cursor.setDate(cursor.getDate() + 1)
```

When the cursor sits on the nonexistent local midnight of the DST spring-forward day, Quickshell's JS engine resolves `setDate` backwards (to the previous day 23:00) instead of forwards to 01:00. `getDate()` then returns the previous day again, producing the duplicate cell, and every later cell inherits a 23:00-based time that keeps the grid one day late relative to the header row.

Node (V8) handles the same loop correctly (`Sat Sep 05 00:00 → Sun Sep 06 01:00 → Mon Sep 07 01:00`), which is likely why the shell's clock tests pass — the engine under Quickshell behaves differently.

## Expected

The grid should keep days aligned with the weekday headers across DST transitions, i.e. `31 1 2 3 4 5 6` for the first row of September 2026 with a Monday week start, putting the 10 under THU.

## Suggested fix

Do date arithmetic in UTC or via explicit field arithmetic instead of local-midnight stepping, e.g. compute cells from `Date.UTC` day offsets, or guard the step with `cursor = new Date(year, month, dayOfCell)` per index rather than mutating one cursor across the gap.

## Steps to reproduce

1. Set system timezone to `America/Santiago` during September 2026 (after the Sep 6 24:00 DST start).
2. Click the bar clock to open the calendar popup.
3. Observe the first week row: duplicate day number, and today's highlight one weekday to the right of the correct column.