Search takes the center — the titlebar placement grammar ratified

Redesign card 6d5a97fd resolved off the 2026-08-01 live try-out: leading is
board identity, center is view controls, trailing stays the user's catalog.
centeredItemIdentifiers, not a flexible-space sandwich — centers against the
window, holds as catalog items install, reaches machines with a saved
arrangement; defaultItems and its pinned tests untouched. 03 records the
grammar and the accepted tensions (widget-vs-field budget in narrow windows,
HIG's trailing convention yielding).

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

DESIGN/03-board-ui.md

@@ -13,7 +13,7 @@ The board window: layout, lanes, cards, and styling. Interaction mechanics (sele
 
 Toolbars are **pure enhancement**: every function they host already has a menu item + shortcut (04-interactions.md's contract), so nothing below is anyone's only path. Both windows' toolbars are **user-customizable, macOS-native** (right-click ▸ Customize Toolbar…, drag to rearrange, system overflow and icon/text display options) — the sets below are shipped defaults, not verdicts. Toolbar item labels match their menu-item titles exactly (Show Trash, Edit Body, Raw Source, …), minus any trailing ellipsis (macOS convention: "Add Attachment…" labels as Add Attachment) — one vocabulary everywhere, and the customize palette self-documents against the menus. One exception: the Undo/Redo toolbar items keep static labels — NSUndoManager rewrites their menu titles dynamically ("Undo Move Card…", 04-interactions.md ▸ Configurable bindings), which a toolbar label doesn't track.
 
-- **Board window default: the search field, nothing else** — trailing, the one default item; the titlebar stays clean. ⌘F always summons search: with the field removed from the toolbar, invoking it surfaces the field transiently until the search clears. **A squeezed field expands in place; the strip answers only genuine unreachability** (blessed 2026-08-06): a space-constrained `NSSearchToolbarItem` collapses to a magnifying-glass button still in the window, and ⌘F expands and focuses it — the toolbar's own field, a better surface than the fallback — so the transient strip fires only for a truly windowless field (true overflow, or the item removed from the toolbar). **The item's overflow row is the platform's own second answer, and the duality is blessed** (2026-08-06): AppKit's overflow menu row carries a live action that widens the window until the field is usable, and suppressing it would destroy the honest overflow presentation — so a squeezed toolbar reaches search two ways with two honest resolutions: ⌘F expands the item or surfaces the strip (ours), the overflow row grows the window (the platform's) — different gestures, reasonable respective outcomes, no contradiction to resolve. **The field is the platform's own search toolbar item and grows on focus** (2026-08-01): the em-derived width is the *focused* width — applied when the field takes the keyboard, expanding via the item's own animation — and the resting width is AppKit's natural one, not the app's to set. **The two-homes width rule is focused-width parity** (ruled 2026-08-01): the width the user *types in* is the same em-derived figure whichever home the field is in — the toolbar item focused, or the transient strip; the toolbar field's resting width is outside the invariant (the strip never rests — it exists only while a search is live or focused, so it has no collapsed state to mirror). **Catalog** (available via Customize): New Card, New Lane, Zoom In, Zoom Out (the zoom pair is catalog-only by the same logic as everything else here — the titlebar's default stays the search field alone; each disables at its end of the ladder, and both disable mid-drag like their menu rows — Layout ▸ zoom above), Undo, Redo (the pair disabled only under locks and on empty stacks — re-ruled 2026-07-31, twice: the provider follows the board, so boards without app-managed git — repo-nested included — bind 13-native-undo.md's native stack in **every** tier and Pro git boards bind the git provider — 06-history-undo.md), Show Trash (toggle state matching the View menu checkmark). The board popover deliberately has **no toolbar item** — the window-title widget is its committed home (below), and a second entry would muddy it.
+- **Board window default: the search field, nothing else** — **centered** (ratified 2026-08-06 off the 2026-08-01 live try-out, reversing the earlier trailing ruling): the titlebar reads as a placement grammar — leading is board identity (the title widget), center is view controls (search today, the filter family if one ever grows), trailing remains the user's catalog space. The mechanism is `NSToolbar.centeredItemIdentifiers`, deliberately not a flexible-space sandwich: it centers against the window rather than leftover space, holds as catalog items install, and sits outside the autosaved configuration, so it takes effect on machines with a saved arrangement — and `defaultItems` is unchanged, keeping the pinned default-set tests standing. The known tensions were weighed and accepted at ratification: the 400pt leading widget and a centered field share the titlebar's budget in narrow windows (the squeezed field's expand-in-place answer below is the relief), and HIG's trailing-edge convention yields to the grammar. The titlebar stays clean. ⌘F always summons search: with the field removed from the toolbar, invoking it surfaces the field transiently until the search clears. **A squeezed field expands in place; the strip answers only genuine unreachability** (blessed 2026-08-06): a space-constrained `NSSearchToolbarItem` collapses to a magnifying-glass button still in the window, and ⌘F expands and focuses it — the toolbar's own field, a better surface than the fallback — so the transient strip fires only for a truly windowless field (true overflow, or the item removed from the toolbar). **The item's overflow row is the platform's own second answer, and the duality is blessed** (2026-08-06): AppKit's overflow menu row carries a live action that widens the window until the field is usable, and suppressing it would destroy the honest overflow presentation — so a squeezed toolbar reaches search two ways with two honest resolutions: ⌘F expands the item or surfaces the strip (ours), the overflow row grows the window (the platform's) — different gestures, reasonable respective outcomes, no contradiction to resolve. **The field is the platform's own search toolbar item and grows on focus** (2026-08-01): the em-derived width is the *focused* width — applied when the field takes the keyboard, expanding via the item's own animation — and the resting width is AppKit's natural one, not the app's to set. **The two-homes width rule is focused-width parity** (ruled 2026-08-01): the width the user *types in* is the same em-derived figure whichever home the field is in — the toolbar item focused, or the transient strip; the toolbar field's resting width is outside the invariant (the strip never rests — it exists only while a search is live or focused, so it has no collapsed state to mirror). **Catalog** (available via Customize): New Card, New Lane, Zoom In, Zoom Out (the zoom pair is catalog-only by the same logic as everything else here — the titlebar's default stays the search field alone; each disables at its end of the ladder, and both disable mid-drag like their menu rows — Layout ▸ zoom above), Undo, Redo (the pair disabled only under locks and on empty stacks — re-ruled 2026-07-31, twice: the provider follows the board, so boards without app-managed git — repo-nested included — bind 13-native-undo.md's native stack in **every** tier and Pro git boards bind the git provider — 06-history-undo.md), Show Trash (toggle state matching the View menu checkmark). The board popover deliberately has **no toolbar item** — the window-title widget is its committed home (below), and a second entry would muddy it.
 - **Card window default: Edit Body · Raw Source · Add Attachment** — the window's three committed functions, all discoverable from its toolbar; the catalog is the same trio. Edit Body is a **single toggle button** (on-state in Edit — mirroring the View ▸ Edit Body checkmark and the ⌘E/Return/Escape grammar; the pathfinder's segmented Preview|Edit is retired). Raw Source is likewise a toggle showing on-state; while source mode is active, Edit Body disables (Cancel/Apply own the exits — 05-card-window.md). Add Attachment stays enabled in every mode — attachment operations never touch `index.md`, so they're safe alongside a raw edit (the sidebar's feedback returns on exit).
 
 ## Lane

Kanban/UI/Board/BoardToolbar.swift

@@ -138,6 +138,11 @@ enum BoardToolbar {
             specs: specs(store: store, search: search),
             defaults: defaultItems
         )
+        // Centered against the window, not a flexible-space sandwich (03 ▸ Toolbar's placement
+        // grammar, ratified 2026-08-06): `centeredItemIdentifiers` holds as catalog items install
+        // and sits outside the autosaved configuration, so it reaches machines that saved an
+        // arrangement under the old trailing default. `defaultItems` is untouched.
+        controller.toolbar.centeredItemIdentifiers = [.boardSearch]
         controller.onInstalledItemsChanged = { [weak search] identifiers in
             search?.isInstalledInToolbar = identifiers.contains(.boardSearch)
         }