`/`` wrappers, or author-owned `role="listitem"` entries. When every assigned child is one of those list-compatible forms, `[part="list"]` supplies `role="list"` and neutral, unroled children temporarily receive `role="listitem"`. Native controls and children with another explicit or native semantic role retain their own semantics; their presence omits list/listitem roles rather than creating an invalid ARIA list context. When every assigned child returns to this list-compatible allowlist, the list/listitem semantics return. **CSS parts:** `base` (outer container), `header` (the clickable `` toggling `expanded`), `toggle` (the chevron indicator inside the header), `list` (wrapper around the default slot, `hidden` while collapsed). **Themeable custom properties:** shared tokens only — `--lr-color-border`, `--lr-color-surface`, `--lr-color-text`, `--lr-color-brand` / `-brand-quiet`, `--lr-radius`, `--lr-space-xs`/`-s`/ `-m`, `--lr-transition-fast`, `--lr-focus-ring-*`. **Optional peer deps:** none. ### `lr-source-card` **Properties:** - `sourceId: string = ''` (attribute `source-id`) — stable identifier matching a `` elsewhere on the page. - `title: string = ''` — the source's display title, e.g. a filename. Falls back to `"Untitled source"` when empty. - `page?: string | number` — optional page reference, e.g. `12` or `"iv"`, rendered as-is (never parsed/validated as a number), appended to the title as `" — p. {page}"`. - `href?: string` — optional URL, echoed back (unopened) in `lr-open`'s detail. - `compact: boolean = false` (reflected) — tighter root padding and row gap, for the dense citation lists these cards usually render in — the same convention as `lr-empty`'s `compact`. Purely a density knob: the border and background stay. `false` (the default) keeps the full card padding. - `frame: LyraFrame = 'card'` (reflected) — container treatment, in the library-wide `frame` vocabulary (`'card' | 'plain'`). `'card'` (the default) keeps the bordered, filled, padded box; `'plain'` removes the border, background, padding and corner radius, so a card inside a `` (or any container already drawing its own border/dividers) doesn't double it. `plain` wins over `compact` when both are set — nothing left to tighten. The title and toggle keep their brand color and hover underline under `plain`, since neither ever depended on the card chrome. Use the shared `LyraFrame` type when authoring this property. - `disabled: boolean = false` (reflected) — turns off this card's OWN controls. The `title` button and the "Show more"/"Show less" `toggle` both render `disabled`, so neither one can emit `lr-open` or `lr-expand` and neither remains in the tab order, and the card paints at `--lr-opacity-disabled` with a `not-allowed` cursor on both. The one `lr-expand` a disabled card can still emit is the automatic collapse when the `full` slot empties while expanded — that reports a state change the card genuinely made, exactly as it does when enabled. Both buttons carry the native `:disabled`, so `::part(title):disabled` / `::part(toggle):disabled` restyle the disabled affordance from outside. Every self-rendered sub-control is gated, not just the primary one: a card whose title is inert but whose disclosure toggle still expands reads as half-broken rather than disabled. Slotted `excerpt`/`full` content stays yours to disable. Not form-associated, so an ancestor `

` does not cascade here. - `aria-pressed` and `aria-current` (attributes only) — forwarded reactively onto the `title` button, the control that carries this card's action, the same mechanism `` and `` use. `aria-pressed` accepts `'true' | 'false' | 'mixed'`; `aria-current` accepts `'page' | 'step' | 'location' | 'date' | 'time' | 'true' | 'false'`. Anything outside those sets is dropped rather than passed through. The `toggle` button never receives either — it already owns `aria-expanded` for its own disclosure state, and two conflicting state claims on one control is worse than one. This is what lets a single-select citation list announce which source is the active one. **Events:** - `lr-expand` (`detail: { sourceId: string; expanded: boolean }`) — the per-card "Show more"/"Show less" toggle was activated. Unrelated to the parent `lr-source-list`'s own expand/collapse, which only ever hides/shows the _set_ of cards, never a single card's own content. - `lr-open` (`detail: { sourceId: string; href?: string }`) — the title was activated. This component never navigates on its own (a controlled component, the same convention ``'s `lr-tool-call-chip-select` follows); a listener decides what "open" means. **Slots:** `excerpt` (a short preview; when left empty, the `excerpt` part collapses away entirely — its wrapper is `hidden`, not just visually empty), `full` (the complete source text/chunk, hidden behind the "Show more"/"Show less" toggle — when left empty, no toggle renders at all; removing all `full`-slotted content while expanded auto-collapses it back). **CSS parts:** `base` (outer container), `title` (the clickable title/page heading, a `

`), `excerpt` (wrapper around the `excerpt` slot, `hidden` when the slot has no assigned content), `full` (wrapper around the `full` slot, `hidden` while collapsed), `toggle` (the "Show more"/"Show less" button — only rendered when the `full` slot has content). **Themeable custom properties:** `--lr-source-card-bg` (default `var(--lr-color-surface)`) — `[part='base']`'s RESTING background, the companion to the `compact` tier's levers below; `frame='plain'` still drops the fill entirely. `--lr-source-card-compact-padding` (default `var(--lr-space-xs)`) — `[part='base']`'s padding while `compact`; `--lr-source-card-compact-gap` (default `var(--lr-space-2xs)`) — the gap between `[part='base']`'s rows while `compact`. Both apply only in the `compact` state, so a dense citation list can be tuned without re-pointing shared spacing tokens elsewhere. Plus shared tokens — `--lr-color-border`, `--lr-color-surface`, `--lr-color-text` / `-text-quiet`, `--lr-color-brand`, `--lr-radius`, `--lr-space-xs`/`-s`, `--lr-focus-ring-*`. **Optional peer deps:** none. ```html Revenue grew 12% year over year... Revenue grew 12% year over year, driven primarily by... No matching full-text chunk for this source. ``` `lr-source-list` removes the card list from the accessibility tree (not just visually hides it) while collapsed, via the native `hidden` attribute on `[part="list"]` — a screen reader user tabbing past the header never lands on off-screen source cards they can't currently see. Both components track slot presence in JS state (`slottedCount` on the list, `hasFullSlot` on the card) rather than relying on CSS `:empty`, since a `[part]` wrapper always contains a literal `` child regardless of assigned content; both also reconcile that state in `firstUpdated()` as a fallback for slot- forwarding scenarios or engines that don't fire `slotchange` for content already present at parse time. **Known gotchas:** - `lr-source-list` does not automatically build an “N sources” plural summary: provide `labelPlural` when that is wanted. Its no-label fallback is localized through `sourceListDefaultLabel`, and a per-instance `.strings` override reaches the rendered header. - `lr-source-card`'s own expand/collapse (`full` slot, `lr-expand` event) is completely independent of the parent list's `expanded`/`lr-toggle` — collapsing the list doesn't reset an individual card's `fullExpanded` state, and there is no cross-talk between the two components at all beyond DOM nesting. - `lr-source-card` actively strips a bare host-level `title` attribute right after Lit syncs it into the `title` property — otherwise the whole card would grow an unsolicited native tooltip repeating the title text on hover. Set `title` only as a property/attribute meant to become the rendered heading; don't rely on it surviving as a DOM attribute afterward. ---