edentext/docs/architecture/ribbon.md

The ribbon

A second chrome above the document, laid out like Word's ribbon. It does not replace the floating command island — chromeMode picks which of the two mounts, so both can be used and compared. Everything the ribbon drives is the same editor, through the same commands.

The mode switch

chromeMode: 'modern' | 'ribbon' lives in storage/theme.ts beside the other UI-chrome prefs (edentext-chrome, default 'ribbon'). App.svelte forks on it: the ribbon docks as a plain flex child, the island keeps its absolute overlay. Reachable from both sides — the theme dropdown in the modern chrome, the strip's appearance menu in the ribbon. The ribbon's menu entry for the island is behind import.meta.env.DEV until the island catches up — a production build offers no way in, but a stored 'modern' pref still loads it.

--toolbar-overlay-h is written only in modern mode. editor.css reads it as var(--toolbar-overlay-h, 0px), so the ribbon's docked layout needs no second rule.

The modern chrome is the baseline the ribbon is measured against, so it stays untouched. Where a shared helper would improve both, the ribbon takes it and the modern chrome keeps its copy; where a dialog is mounted inside ToolbarExpanded, the ribbon mounts its own rather than hoisting it. Only one chrome is mounted at a time, so the two sets never coexist.

Palette

Word's greys live in --w-* in global.css — its own token set, not the app's, so the two chromes can look nothing alike while sharing a theme. The accent is not Word's blue but the logo's slate, --brand-slate (#4c6c8a, 5.1:1 on the chrome and carries white); the tab's active underline is 2.5px inset 13px from each side, not a full-width border.

The logo's other colour, --brand-clay, marks the contextual tabs — the ones that exist only for the selected object — as their 2px bar, over a --w-contextual label darkened to stay readable (the clay itself is 3.3:1 on white). Both brand tokens are defined once, from favicon.svg; the modern chrome's island hairline already gradients between the same pair.

.ribbon remaps the app's own tokens onto that palette (--color-surface, --color-primary, --toolbar-btn-size, …). Custom properties inherit, so every reused picker — ColorPicker, HistoryButton, TablePicker, TableStylePicker, the border pickers — adopts the ribbon's look with no edit of its own, while the modern toolbar keeps the themed set. The status bar takes the same remap while the ribbon is mounted (.statusbar.w-chrome, App.svelte) — it closes the frame the chrome opens, and the app's dark neutrals are bluer than Word's.

Dark flips only the colours — every metric holds, so it is the same ribbon. The neutrals are Word's dark mode: Fluent's dark neutrals, chrome #1f1f1f on surface #292929; both brand tones lighten (#8fb3cd / #e2916f), unreadable on a dark chrome otherwise. AllBlack goes on to Word's Black theme (#0f0f0f), since the app's AllBlack canvas is darker than its dark one.

That lightened accent cannot also carry white text, so a second pair exists for the one place the accent is a surface rather than a line: --w-accent-fill / -fill-open, on the File pill and on --color-primary for the pickers. In light mode both equal --w-accent / --w-accent-dark, so the split is invisible there.

Layout

Ribbon.svelte
├─ .ribbon-tabs     File pill · quick access (save, undo, redo) · tabs · contextual tabs
│                   · spacer · document name · appearance · UI language
└─ .ribbon-body     the active tab's groups, a fixed --w-ribbon-h (84px) band

The band's height never changes: it scrolls horizontally with a hidden scrollbar instead of collapsing groups into popovers the way Word does when the window narrows. That is the single biggest simplification here, and the reason two things below are necessary.

84px is the tallest control in any tab — Table Layout's two-line Insert above, 65px — plus the group footer and the band's padding, so no tab carries dead space above its buttons. Every metric feeding that sum is pinned in px, line-heights included: a ratio hands the band's height to whatever font resolves, and the group footers then hang out of the band.

A chevron in the tab strip drops the band entirely, leaving the strip (edentext-ribbon-collapsed). Clicking any tab brings it back — Word instead floats it over the document until the next click lands in the text, which is the part not built.

Word puts that chevron in the band's bottom-right corner, and this one did too. Both ways of reserving that corner failed: as a layer it covered whichever group's dialog launcher reached the edge, and since the band scrolls, which one that is varies; in the flow it cost the band a column at every height. A flex row cannot reserve width in part of its height, so it moved to the strip.

• A menu must leave the flow. .ribbon-body clips its own overflow, so the anchored action (ribbon/menu.svelte.ts) switches a panel to position: fixed and pins it under its wrapper, clamped inside the window. Panels drop below the whole band, not below their own button — inside it they would cover the controls and group labels underneath. A panel has to be out of the flow (position: absolute) before it mounts: in it, it stretches the wrapper anchored measures and lands its own height too low.
• A reused picker anchors its panel itself, and no prop says when it opened. pinPanels, one action on the band, watches for a mounted absolutely-positioned node and pins that; the ColorPicker places its own and only needs the band-aware top.
• Insert caption sits in three tabs: References, where both products keep it, plus the picture/shape and Table Layout contextual tabs, which are open anyway when you caption something. Each mounts its own CaptionDialog; it reads the caret for its category, so the copies need no props of their own.
• Each wrapper names the menu it owns. One shared open-menu id means every clickOutside sees every mousedown; without the id each wrapper would close a sibling's open menu, and the click on one of its rows would never land.

Pieces

File	Role
Ribbon.svelte	Shell, tab state, the File menu, which contextual tabs are shown
RibbonGroup.svelte	A group: its controls, its visible label, Word's ↘ dialog launcher
RibbonButton.svelte	big / small / icon, plus the split button. Hover paints the icon box, not the whole button. A big label wraps onto two lines at a 78px cap and its caret rides beside the icon, so a three-word label costs width instead of a third row
RibbonMenu.svelte	The dropdown panel; its look is global CSS, since its rows come from a caller's snippet
Icon.svelte, icons.ts	Path data on a 16-unit canvas. pinnedStroke(size) holds the painted stroke at ~1.5px on large glyphs and ~1.1px on small ones, so 14px and 28px icons read as one family
menu.svelte.ts	The one open-menu id, anchored, pinPanels, clickOutside
selection.ts	saveRange / withRange — a popover steals focus, so the range is replayed before the command
fontList.svelte.ts	Recent, web-safe and detected fonts, shared by every font picker
controls/	Font family box, font size box, style gallery
.rb-captioned (global.css)	Wraps a reused picker standing alone in a group: its trigger grows to the big button's 32px box and 28px glyph, so a group of pickers and a group of buttons are the same size
tabs/	One file per tab

Reading what the selection formats is not here: utils/selectionFormat.ts answers it framework-free (uniformFont, uniformFontSize, uniformMarkColor, uniformBlockAttr), each returning the shared value or '' when the selection mixes two.

Tabs

Fixed: File (a menu, not a backstage) · Home · Insert · Layout · References · Review · View. Contextual, shown while the caret is in the object: Table Design, Table Layout, Picture Format, Shape Format — a tab that disappears hands the strip back to Home.

The ribbon surfaces a good deal the engine already carried with nothing to reach it: change case, underline and strikethrough line styles, Find and Replace as buttons, the page break, section breaks, absolute left/right indent, the table-of-contents depth and its page numbers, cell margins, Save As.

Dialogs

ParagraphDialog and TabsDialog open from Word's ↘ launcher in a group's corner. They are chrome-agnostic, so the modern chrome could gain launchers of its own at no cost.

There is no Font dialog: the Home tab already carries change case and the underline and strikethrough line styles, and the two things left over — letterSpacingPt and kerning — live on a named style, not on a run. Setting them as direct formatting would mean a new mark attribute and export work on both formats, which is more than a chrome rebuild. The style manager is where they belong.

What retiring the modern chrome would free

Recorded so the option stays visible, not as a plan: Toolbar.svelte and ToolbarExpanded.svelte (~3200 lines), the overlay island and its hand-rolled horizontal scrollbar in App.svelte (~120 lines plus CSS), the pointer-events opt-ins, --toolbar-overlay-h, the collapsed-toolbar re-fire shim, loadToolbarExpanded / saveToolbarExpanded, the duplicate dialog mounts, and ToolbarExpanded's own copies of the selection readers.