Fill handle: Fill Days, Fill Weekdays, Fill Months and Fill Years for a date

When a fill starts from a date, the right-drag fill menu and the Auto
Fill Options button now also offer Fill Days, Fill Weekdays, Fill Months
and Fill Years. edit.autoFill takes them as the modes days, weekdays,
months and years.

A lone date steps by one unit. Two or more dates step by the difference
between the first two in that unit, or by one unit when both fall in
the same one. Fill Weekdays skips Saturday and Sunday, and a start on a
weekend moves to the next weekday first. Fill Months and Fill Years keep
the day of the month, clamped to the month's last day. A source that is
not all dates fills as a plain drag does.

Fills by months or years now keep the time of day of a date with a
time. A plain drag of dates a month apart and Series by Month or Year
used to drop it.

docs/ui-parity.md

@@ -1,6 +1,6 @@
 # UI parity
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-23 · **Change:** minor (New Formatting Rule's formula box takes references clicked or dragged on the grid, #2348; Page Up and Ctrl+Up into frozen rows, Ctrl+Left and Alt+Page Up into frozen columns bring the scrolled area back; Auto Fill Options button after a left-drag of the fill handle (#1403); Show Outline Symbols, Ctrl+8; a too-wide number in a repeat-fill format such as Accounting shows #### instead of losing its leading digits; Esc and Enter close a data validation alert over the cell editor; Ctrl+Enter fill gives each cell the automatic number format typing gives it; keytip letters typed with Alt held, #1846; Number Stored as Text indicator and Convert to Number) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-24 · **Change:** minor (Fill Days, Fill Weekdays, Fill Months and Fill Years in the fill-handle menus for a date; New Formatting Rule's formula box takes references clicked or dragged on the grid, #2348; Page Up and Ctrl+Up into frozen rows, Ctrl+Left and Alt+Page Up into frozen columns bring the scrolled area back; Auto Fill Options button after a left-drag of the fill handle (#1403); Show Outline Symbols, Ctrl+8; a too-wide number in a repeat-fill format such as Accounting shows #### instead of losing its leading digits; Esc and Enter close a data validation alert over the cell editor; Ctrl+Enter fill gives each cell the automatic number format typing gives it; keytip letters typed with Alt held, #1846; Number Stored as Text indicator and Convert to Number) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Interaction, controls and feel, against Excel. Part of [target-app-parity.md](target-app-parity.md).
 **UI/UX fidelity: ~55% ready, 50–80 h** (estimated). Ribbon command coverage is measured
@@ -50,7 +50,7 @@ this logic, with one undo step.
 | Click/drag/Shift/Ctrl selection, multi-area selection | rectangular drag works in one direction only in some cases (#28) |
 | Cursor while dragging cells, headers, freeze handles and objects | stable for the active drag (#936); Draw tools keep their crosshair; header arrows and a custom cell cursor remain unimplemented |
 | Selection outline glides to a new selection (Excel: "Provide feedback with animation") | done (10-11): 0.12 s, decelerating, with the fill and fill handle; View ▸ Animations (`view.animations`) turns it off. The timing is an estimate, not yet measured against Excel; the system's reduced-motion setting isn't followed yet |
-| Fill handle: drag to fill series, double-click to fill down, right-drag menu | fill done (Ctrl+drag swaps copy and series; month patterns use the workbook's 1900 or 1904 date system); right-drag menu partial: Copy Cells, Fill Series, Fill Formatting Only, Fill Without Formatting, Series…; a left-drag leaves an Auto Fill Options button with the first four (gone once the workbook changes or the selection moves); Fill Days/Weekdays/Months/Years, Linear/Growth Trend and Flash Fill missing |
+| Fill handle: drag to fill series, double-click to fill down, right-drag menu | fill done (Ctrl+drag swaps copy and series; month patterns use the workbook's 1900 or 1904 date system); right-drag menu partial: Copy Cells, Fill Series, Fill Formatting Only, Fill Without Formatting, and from a date Fill Days, Fill Weekdays, Fill Months and Fill Years, then Series…; a left-drag leaves an Auto Fill Options button with the same fill choices (gone once the workbook changes or the selection moves); Linear/Growth Trend and Flash Fill missing |
 | Drag-move and drag-copy cells (border drag, Ctrl/Option, Shift to insert) | done (M3) |
 | In-cell editing, Enter/Tab movement, Alt/Option+Enter line breaks | done |
 | Point mode (click/drag/arrow references), reference colouring, F4 | done; Command/Ctrl-click adds separate arguments with the edit's locale separator, and Shift-click extends the current reference from a fixed anchor on the same sheet. Pointer-event regressions cover repeated/reversed selections, manual separators, sheet switches and keyboard continuation. |
@@ -181,6 +181,7 @@ scrollbar bugs 2–4 · pixel/feel pass against observed Excel 7–12.
 | 2026-10-23 | minor | Conditional Formatting ▸ New Rule, formula: clicking a cell on the grid writes its absolute reference at the formula box's caret (`=$B$2`, an empty box starts with `=`), a drag writes a range (`$B$2:$C$4`) and a second click replaces the reference just written, as in Excel ("Selecting cells on the worksheet inserts absolute cell references"). The selection the rule applies to doesn't move, and the box keeps the keyboard. After an operand (`=A1>5`) the click does nothing (#2348) |
 | 2026-10-23 | minor | Frozen panes: Page Up, Ctrl+Up and Shift variants that move from the scrolled rows into the frozen ones bring the scrolled rows back to the top, so the rows in between are seen again (Page Up from far down used to end on row 1 with the view still a page down); Ctrl+Left and Alt+Page Up do the same for frozen columns. Other ways of selecting a frozen cell (click, Find, Go To, Undo, formula pointing) leave the view where it is |
 | 2026-10-23 | minor | After a left-drag of the fill handle an Auto Fill Options button sits below the filled cells; its menu redoes the fill as Copy Cells, Fill Series, Fill Formatting Only or Fill Without Formatting (undoes the drag's fill, then `edit.autoFill` in that mode). It goes away when the workbook changes or the selection moves (#1403) |
+| 2026-10-24 | minor | When the fill starts from a date, the right-drag fill menu and the Auto Fill Options button also offer Fill Days, Fill Weekdays (Saturday and Sunday skipped), Fill Months and Fill Years (`edit.autoFill` `mode: days|weekdays|months|years`). A lone date steps by one unit; two or more dates step by the difference between the first two in that unit, or one unit when they fall in the same one. Fill Months and Fill Years keep the day of the month, clamped to the month's last day. Every fill by months or years (these two, a drag of dates a month apart, and Series by Month or Year) keeps the time of day of a date with a time, which used to be dropped |
 | 2026-10-22 | minor | Show Outline Symbols (`view.showOutlineSymbols`, Ctrl+8): a sheet can hide the outline's level buttons and brackets while keeping its outline, as Excel saves with `showOutlineSymbols="0"` (read and written); the grid then gives the bands no room |
 | 2026-10-22 | minor | A number in a repeat-fill format (`*`, as in the Accounting format) that is too wide for its column shows #### like any other number, instead of the fill rebuilding the value so its leading digits were cut off (2,509.00 CHF drawn as "509.00 CHF") |
 | 2026-10-21 | minor | Background error checking, first part (#1994): a constant whose text would be a number if typed (signs, thousands, currency, percent, exponent, parenthesised negative) gets Excel's green corner triangle; the active cell then shows a warning button whose menu names the problem and offers Convert to Number for the selection (`formulas.convertToNumber`). Dates, times and fractions kept as text and formula results are not flagged, as in Excel |