Collection perf + a11y sign-off (2.64)

Closes FL-008 (documented perf paths) and FL-016 (DataTable pin/group) for ops LoB — collection wave 10 in performance.md.

Related: data-collections.md · accessibility.md · tree-data.md · planning/friction-log.md (FL-008, FL-016) · Gallery DataTable, ListDetailsView, FileTree pages.

Controls: DataTable · ListDetailsView · TreeDataGrid · FileTree — import QWinUI3.Extras.

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Goal

Product apps need spreadsheet-style tables and mail-style master–detail without dropping kit controls at a few hundred rows. 2.64 deepens collection APIs from component-capabilities-expansion.md:

Control	2.64 capability
DataTable	Column pin (pinned: true), group headers (groupRole), columnOrder / moveColumn
ListDetailsView	multiSelectEnabled, selectedItems, detailToolbar bulk actions
TreeDataGrid	Column resize handles; freezeFirstColumn API (name column)
FileTree	filterText sync to table; hiddenColumnRoles + column chooser

Out: Million-row GPU grid; C++ model rewrite.

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DataTable — pin + group recipe

DataTable {
    id: opsTable
    groupRole: "team"
    columns: [
        { title: qsTr("Name"), role: "name", width: 160, pinned: true, sortable: true },
        { title: qsTr("Role"), role: "role", width: 140, sortable: true },
        { title: qsTr("Team"), role: "team", width: 120, sortable: true },
        { title: qsTr("Status"), role: "status", width: 110, sortable: true }
    ]
    rows: employeeRows
    // Persist column order from Settings:
    // columnOrder: settings.tableColumnOrder
    // onColumnLayoutChanged: settings.tableColumnOrder = columnOrder
}

• Pinned columns stay fixed while horizontal-scrolling the rest.
• Group headers insert non-selectable rows when groupRole is set (sort applies before grouping).
• Bind columnOrder to app settings for reorder persistence across sessions.

Gallery: DataTable page — 2.64 block (grouped + pinned demo).

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ListDetailsView — multi-select toolbar

ListDetailsView {
    id: mail
    multiSelectEnabled: true
    model: messages
    detailToolbar: RowLayout {
        Label { text: qsTr("%1 selected").arg(mail.selectionCount) }
        Button {
            text: qsTr("Archive")
            enabled: mail.selectionCount > 0
            onClicked: archiveRows(mail.selectedItems)
        }
        Button {
            flat: true
            text: qsTr("Clear selection")
            visible: mail.selectionCount > 0
            onClicked: mail.clearMultiSelection()
        }
    }
    details: MessageBody { item: mail.selectedItem }
}

• Ctrl+click toggles checkboxes; Shift+click range-selects; Ctrl+A selects filtered master rows.
• selectedIndex still drives the detail pane; selectedItems powers bulk commands.

Gallery: ListDetailsView page — mail bulk-action demo.

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Tree / file polish

Control	Pattern
TreeDataGrid	Drag header splitters to resize; set freezeFirstColumn: true for wide hierarchies
FileTree	filterText filters the file table; toggle columns via hiddenColumnRoles

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Performance checklist (wave 10)

#	Check	API
1	Filter debounce	filterDebounceMs (120) on DataTable / ListDetailsView
2	Cap JS filter walk	maxFilterResults on huge arrays
3	Virtualize rows	ListView.reuseItems (built-in)
4	Skip unchanged rebuild	_lastRefreshKey / _lastFilterKey
5	Pin identity columns	columns[].pinned — less horizontal hunting
6	Group before paint	groupRole — ops dashboards scan by team/status
7	Bulk without ItemsView	ListDetailsView multi-select + toolbar

Named paths: filter keystroke → debounce → capped walk; ops table → pin name → group by team; mail list → multi-select → archive toolbar.

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Accessibility (2.64)

• DataTable group headers expose Accessible.StaticText; pinned headers announce ", pinned".
• ListDetailsView checkboxes named Select {title}; multi-count announced on toggle.
• NavigationView live-region paths from 2.07 remain Done — no regressions in sign-off.

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App checklist

1. Set maxFilterResults when JS arrays exceed a few hundred rows.
2. Pin the primary identity column (name, id) for wide ops tables.
3. Use detailToolbar for bulk actions instead of a second ItemsView.
4. Persist columnOrder (and widths if needed) via app settings.
5. Run Gallery --smoke after upgrading — collection pages are in the smoke path.