### Goal

Extract a reusable BorderBox-backed list Begin of the insertioncomponentEnd of the insertion Begin of the deletion primitiveEnd of the deletion into Begin of the insertion`OpenProject::Common::BorderBoxListComponent`, collapsing the previously proposed `OpPrimer`End of the insertion Begin of the deletion `OpPrimer::BorderBoxListComponent`, move generic header/action/menu chrome into that primitive,End of the deletion and Begin of the insertion`OpenProject::Common` layers into a single domain-aware component. Move the automatic collection wrapper (`WorkPackageCardListComponent`) into the `Backlogs` namespace as an internal component.End of the insertion Begin of the deletion keep OpenProject domain-specific item support outside `OpPrimer`.End of the deletion

This Begin of the insertionsupersedes the three-layer designEnd of the insertion Begin of the deletion implementation is a static component extraction. Generic header actions, header menus, and item menus areEnd of the deletion in Begin of the insertionPR #23074. ~~A new branch off~~ `~~dev~~` ~~will be used.~~End of the insertion Begin of the deletion scope as reusable list chrome. Sorting, reordering, drag-and-drop ordering APIs, and action-menu abstractions beyond these explicit slots are out of scope for this work package.End of the deletion

### Component API

Begin of the insertion`OpenProject::Common::BorderBoxListComponent` renders `Primer::Beta::BorderBox` directly withEnd of the insertion Begin of the deletion `OpPrimer::BorderBoxListComponent` should provideEnd of the deletion these Begin of the deletion genericEnd of the deletion slots:

Begin of the insertion* End of the insertion Begin of the deletion -End of the deletion `header` Begin of the insertion— structuredEnd of the insertion Begin of the deletion
- `with_item`
- `with_empty_item`
- `footer`

The public collection slot should be called `items`, to distinguish the wrapper API from the underlying `Primer::Beta::BorderBox` row implementation. Callers are responsible for calling item slot methods in the order they want items rendered. The component should render through Primer BorderBox under the hood and forward relevant system arguments such as ids, list ids, padding, classes, data attributes, and ARIA attributes.

The genericEnd of the deletion header Begin of the insertionwith `title:`,End of the insertion Begin of the deletion should support title,End of the deletion optional Begin of the insertion`count:`, `with_description`, `with_action_button` (plural),End of the insertion Begin of the deletion count, description, action buttons,End of the deletion and Begin of the insertion`with_menu` (kebab via `HasMenu` module)

* `with_item` —End of the insertion Begin of the deletion a menu slot. TheEnd of the deletion generic Begin of the deletion item should render arbitraryEnd of the deletion content Begin of the insertionrow, arbitrary block content, noEnd of the insertion Begin of the deletion and expose an optionalEnd of the deletion menu Begin of the insertionsub-slot

* `with_work_package_item` — domain-specific row accepting `work_package:`, `project:`, `params:`, optional `component_klass:` (defaults to `BorderBoxListComponent::WorkPackageItem`).End of the insertion Begin of the deletion slot.End of the deletion The Begin of the insertionlist injects `container:` and `current_user:` automatically.

* `with_empty_state` — rendered when items collection is empty. Accepts `title:`, `description:`, `icon:`. Always renders a `Primer::Beta::Blankslate`.

* `footer` — proper `Primer::Beta::BorderBox`End of the insertion footer Begin of the insertion


Constructor: `initialize(container:, current_user: User.current, **system_arguments)`

`container:` is required and derives box, list, and header DOM IDs via `dom_target`. CallersEnd of the insertion should Begin of the insertionpass structured references (model, symbol, or array)End of the insertion Begin of the deletion continue to render as a BorderBox rowEnd of the deletion rather than Begin of the insertionpre-computed strings.End of the insertion Begin of the deletion a BorderBox footer, preserving the existing list-body DOM contract.End of the deletion

Begin of the insertionItems are polymorphic (`with_item`End of the insertion Begin of the deletion `OpPrimer::BorderBoxListComponent` must not expose work-package-specific slots or classes.

### OpenProject list specialization

Add `OpenProject::Common::BorderBoxListComponent` as the manual OpenProject-specialized layer around `OpPrimer::BorderBoxListComponent`.

It should compose an `OpPrimer::BorderBoxListComponent` instance, delegate the generic slot methods to it,End of the deletion and Begin of the deletion provide the generic list slots plus:

-End of the deletion `with_work_package_item` Begin of the deletion

`with_work_package_item` provides a work-package item bridge through a configurable item/card component. This keeps work-package supportEnd of the deletion in Begin of the insertionthe same collection). Callers control render order. No auto-iteration — thisEnd of the insertion Begin of the deletion `OpenProject::Common`, while still allowing manual callers to interleave work-package items with custom items. ThisEnd of the deletion component Begin of the insertionnever acceptsEnd of the insertion Begin of the deletion must not acceptEnd of the deletion `work_packages:` Begin of the insertionas a collection.End of the insertion Begin of the deletion and must not perform automatic collection iteration.End of the deletion

Begin of the insertion### WorkPackageItem baseEnd of the insertion Begin of the deletion The work-package item componentEnd of the deletion class Begin of the insertion

`BorderBoxListComponent::WorkPackageItem` is a base class nested underEnd of the insertion Begin of the deletion should be configurable once onEnd of the deletion the list Begin of the insertioncomponent. It rendersEnd of the insertion Begin of the deletion throughEnd of the deletion a Begin of the insertionbasic work-package card via `WorkPackageCardComponent` without module-specific behavior. `Backlogs::WorkPackageCardListItemComponent` inherits from it and adds drag-and-drop, story data, and backlogs-specific menu URLs.End of the insertion Begin of the deletion constructor-level `work_package_item_component:` default, with per-item `component_klass:` override support.End of the deletion

Begin of the deletion This component is also the future home for other explicit OpenProject-specialized item slots, such as meeting items, if those become useful.

End of the deletion ### Begin of the insertionBacklogsEnd of the insertion Begin of the deletion Work packageEnd of the deletion wrapper

Begin of the insertion`Backlogs::WorkPackageCardListComponent` (moved from `OpenProject::Common`) isEnd of the insertion Begin of the deletion `OpenProject::Common::WorkPackageCardListComponent` should remainEnd of the deletion the automatic collection-oriented wrapper. Begin of the insertionInternal to Backlogs, not yet ready for sharing.End of the insertion

It Begin of the insertionaccepts `project:`, `container:`, `work_packages:`, `drag_and_drop:`, `params:`, `current_user:`. Hardcodes `Backlogs::WorkPackageCardListItemComponent` during auto-iteration. Delegates `with_header` (with fold-state defaults), `with_footer`, and `with_empty_state`End of the insertion Begin of the deletion should continueEnd of the deletion to Begin of the deletion support:

- `project:`
- `container:`
- `work_packages:`
- `drag_and_drop:`
- `item_component_klass:`
- `params:`
- `current_user:`
- delegated `header`
- delegated `footer`
- `empty_state`

When `work_packages:` are passed, `WorkPackageCardListComponent` should iterateEnd of the deletion the Begin of the deletion collection itself and add work-package items through `OpenProject::Common::BorderBoxListComponent`. When no work packages are rendered, it should render `empty_state` through theEnd of the deletion underlying Begin of the insertion`BorderBoxListComponent`.End of the insertion Begin of the deletion empty item slot.End of the deletion

Begin of the deletion `WorkPackageCardListComponent` should not expose manual item composition. Manual interleaving belongs to `OpenProject::Common::BorderBoxListComponent`.

End of the deletion ### Backlogs adoption

`Backlogs::InboxComponent` Begin of the insertionusesEnd of the insertion Begin of the deletion should useEnd of the deletion `OpenProject::Common::BorderBoxListComponent` Begin of the insertiondirectly (manual composition forEnd of the insertion Begin of the deletion directly, because it interleaves a customEnd of the deletion show-more Begin of the insertioninterleaving).End of the insertion Begin of the deletion item between work-package items.End of the deletion

`Backlogs::SprintComponent` and `Backlogs::BucketComponent` Begin of the insertionuse `Backlogs::WorkPackageCardListComponent` (automatic collection).End of the insertion Begin of the deletion should stay on `OpenProject::Common::WorkPackageCardListComponent`, because they render automatic work-package collections.End of the deletion

### Compatibility expectations

Existing Begin of the deletion backlogs rendering should keep the relevantEnd of the deletion DOM Begin of the insertioncontract preserved: container/list/header IDs via `dom_target`,End of the insertion Begin of the deletion contract:

- container id from `dom_target(container)`
- list id from `dom_target(container, :list)`
- header id and collapsible linkage
-End of the deletion work package item Begin of the insertionIDs/classes/dataEnd of the insertion Begin of the deletion ids, classes, dataEnd of the deletion attributes, Begin of the deletion and card rendering
- empty item marker
- footer item styling
-End of the deletion drag-and-drop Begin of the insertiondata, collapsible header linkage, empty state rendering.End of the insertion Begin of the deletion data on the boxEnd of the deletion

### Tests

Begin of the insertionFocusedEnd of the insertion Begin of the deletion Add or update focusedEnd of the deletion component specs for Begin of the insertion`OpenProject::Common::BorderBoxListComponent`End of the insertion Begin of the deletion `OpPrimer::BorderBoxListComponent`End of the deletion covering: Begin of the deletion

- header, generic item, empty item, item menu, and footer rendering
- forwarding of system arguments to the underlying BorderBox
-End of the deletion header Begin of the insertion(title, count,End of the insertion description, Begin of the insertionaction buttons,End of the insertion Begin of the deletion actions,End of the deletion menu, Begin of the insertioncollapsible), generic items, work-package items (defaultEnd of the insertion and Begin of the insertionoverridden `component_klass:`, injected `container:`/`current_user:`),End of the insertion Begin of the deletion count behavior
-End of the deletion empty Begin of the insertionstate as Blankslate, footer, container-derived DOM IDs, system argument forwarding.End of the insertion Begin of the deletion item data merging
- no work-package references under `OpPrimer`End of the deletion

Begin of the insertionFocusedEnd of the insertion Begin of the deletion Add focusedEnd of the deletion component specs for Begin of the insertion`Backlogs::WorkPackageCardListComponent`End of the insertion Begin of the deletion `OpenProject::Common::BorderBoxListComponent`End of the deletion covering: Begin of the insertionauto-iteration,End of the insertion Begin of the deletion

- generic item pass-through throughEnd of the deletion delegated Begin of the deletion slots
- constructor-level `work_package_item_component:` default
- per-item `component_klass:` override
- work-package item rendering through a supplied component class
- work-package item customization blocks
- no automatic collection iteration

Update/keep `WorkPackageCardListComponent` specs covering:

- automatic `work_packages:` iteration
- delegatedEnd of the deletion header Begin of the insertionwith fold-state, footer,End of the insertion Begin of the deletion and footer rendering
- `empty_state` rendering through theEnd of the deletion empty Begin of the insertionstate,End of the insertion Begin of the deletion item slot
- container/list/header ids
- existing backlogs item data/classes andEnd of the deletion drag-and-drop Begin of the insertiondata, DOM IDs.End of the insertion Begin of the deletion dataEnd of the deletion

Begin of the insertionUpdatedEnd of the insertion Begin of the deletion UpdateEnd of the deletion backlogs Begin of the insertioncallerEnd of the insertion Begin of the deletion componentEnd of the deletion specs Begin of the insertionfor InboxComponent, SprintComponent, BucketComponent,End of the insertion Begin of the deletion to ensure the inbox show-more item remains interleavedEnd of the deletion and Begin of the insertionWorkPackageCardListItemComponent inheritance chain.End of the insertion Begin of the deletion sprint/bucket DOM contracts remain stable.End of the deletion