Reader: resizable side panel

Drag the left edge of the verse side panel to resize it (arrow keys too,
Shift for bigger steps; double-click resets). The text reflows to make room,
and the width is remembered on this device. Reuses the Study page's resize
handle; the hook now takes the CSS variable to drive.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/components/reader/Sheet.jsx

@@ -7,7 +7,7 @@ import { CloseIcon } from './icons.jsx';
 
 const FOCUSABLE = 'a[href], button:not([disabled]), input:not([disabled]), select:not([disabled]), textarea:not([disabled]), [tabindex]:not([tabindex="-1"])';
 
-export default function Sheet({ open, onClose, title, label, headerRight, modal = true, pane = false, children }) {
+export default function Sheet({ open, onClose, title, label, headerRight, modal = true, pane = false, panelRef, edge, children }) {
   const dialogRef = useRef(null);
   const onCloseRef = useRef(onClose);
   onCloseRef.current = onClose;
@@ -41,15 +41,16 @@ export default function Sheet({ open, onClose, title, label, headerRight, modal
     <>
       {modal && <div className="fixed inset-0 z-40 bg-black/30" onClick={onClose} aria-hidden="true" />}
       <div
-        ref={dialogRef}
+        ref={(el) => { dialogRef.current = el; if (panelRef) panelRef.current = el; }}
         role="dialog"
         aria-modal={modal ? 'true' : undefined}
         aria-label={typeof title === 'string' ? title : label}
         tabIndex={-1}
         className={`fixed inset-x-0 bottom-0 z-50 flex max-h-[72vh] flex-col rounded-t-2xl focus:outline-none border-t border-[var(--r-line)] bg-[var(--r-bar)] text-[var(--r-text)] font-sans ${
-          pane ? 'lg:inset-x-auto lg:bottom-0 lg:right-0 lg:top-12 lg:max-h-none lg:w-[24rem] lg:rounded-none lg:border-l lg:border-t-0' : 'sm:left-1/2 sm:right-auto sm:w-[36rem] sm:-translate-x-1/2'
+          pane ? 'lg:inset-x-auto lg:bottom-0 lg:right-0 lg:top-12 lg:max-h-none lg:w-[var(--reader-pane,24rem)] lg:rounded-none lg:border-l lg:border-t-0' : 'sm:left-1/2 sm:right-auto sm:w-[36rem] sm:-translate-x-1/2'
         }`}
       >
+        {edge}
         <div className="mx-auto mt-2 h-1 w-9 shrink-0 rounded-full bg-[var(--r-line)] lg:hidden" />
         <div className="flex items-center justify-between gap-2 px-4 pb-2 pt-2">
           <div className="min-w-0 truncate text-sm font-medium">{title}</div>

src/components/reader/VerseSheet.jsx

@@ -142,7 +142,7 @@ function CompareTab({ book, chapter, verse, current }) {
 export default function VerseSheet({
   verse, book, bookName, chapter, translation, words, crossRefs, crossRefsLoading, onLoadCrossRefs,
   bookmarkColor, onToggleBookmark, onCycleColor, onJump, onClose, request,
-  verseHighlights = [], colorLabels = {}, onHighlightVerse, onClearVerseHighlights,
+  verseHighlights = [], colorLabels = {}, onHighlightVerse, onClearVerseHighlights, panelRef, resizeHandle,
 }) {
   const [tab, setTab] = useState('commentary');
   const [copied, setCopied] = useState(false);
@@ -175,7 +175,7 @@ export default function VerseSheet({
 
   return (
     <Sheet
-      open modal={false} pane onClose={onClose}
+      open modal={false} pane onClose={onClose} panelRef={panelRef} edge={resizeHandle}
       title={`${bookName} ${chapter}:${verse.number}`}
       headerRight={(
         <>

src/hooks/useResizableWidth.js

@@ -6,7 +6,8 @@ const STEP = 24;
 const BIG_STEP = 96;
 
 // containerRef: the element the panel sits at the right edge of (for measuring and clamping).
-export function useResizableWidth({ storageKey, min = 320, maxAbsolute = 760, fallback = 448, reserve = 600, containerRef }) {
+// cssVar: the custom property on the container that carries the width while dragging.
+export function useResizableWidth({ storageKey, min = 320, maxAbsolute = 760, fallback = 448, reserve = 600, containerRef, cssVar = '--study-right' }) {
   const maxFor = () => {
     const w = containerRef.current?.getBoundingClientRect().width ?? 0;
     return w > 0 ? Math.max(min, Math.min(maxAbsolute, w - reserve)) : maxAbsolute;
@@ -51,7 +52,7 @@ export function useResizableWidth({ storageKey, min = 320, maxAbsolute = 760, fa
       const right = containerRef.current?.getBoundingClientRect().right ?? window.innerWidth;
       const next = clamp(right - e.clientX);
       dragRef.current.width = next;
-      containerRef.current?.style.setProperty('--study-right', `${next}px`); // smooth: no React render per move
+      containerRef.current?.style.setProperty(cssVar, `${next}px`); // smooth: no React render per move
     },
     onPointerUp: (e) => {
       if (!dragRef.current) return;
@@ -65,9 +66,9 @@ export function useResizableWidth({ storageKey, min = 320, maxAbsolute = 760, fa
       const step = e.shiftKey ? BIG_STEP : STEP;
       if (e.key === 'ArrowLeft') { e.preventDefault(); commit(clamp(current(panelRef.current) + step)); }
       else if (e.key === 'ArrowRight') { e.preventDefault(); commit(clamp(current(panelRef.current) - step)); }
-      else if (e.key === 'Home' || e.key === 'Escape') { e.preventDefault(); containerRef.current?.style.removeProperty('--study-right'); commit(null); }
+      else if (e.key === 'Home' || e.key === 'Escape') { e.preventDefault(); containerRef.current?.style.removeProperty(cssVar); commit(null); }
     },
-    onDoubleClick: () => { containerRef.current?.style.removeProperty('--study-right'); commit(null); },
+    onDoubleClick: () => { containerRef.current?.style.removeProperty(cssVar); commit(null); },
     title: 'Drag to resize · double-click to reset',
   });
 

src/hooks/useResizableWidth.test.js

@@ -79,3 +79,12 @@ test('the handle describes itself for assistive technology', () => {
   const props = setup().handle();
   expect(props).toMatchObject({ role: 'separator', 'aria-orientation': 'vertical', 'aria-label': 'Resize side panel', tabIndex: 0, 'aria-valuenow': 448 });
 });
+
+test('a different panel can name its own CSS variable', () => {
+  const h = setup({ cssVar: '--reader-pane' });
+  act(() => { down(h); move(h, 1000); });
+  expect(h.style.setProperty).toHaveBeenLastCalledWith('--reader-pane', '400px');
+  act(() => up(h));
+  act(() => { h.handle().onDoubleClick(); });
+  expect(h.style.removeProperty).toHaveBeenLastCalledWith('--reader-pane');
+});

src/pages/ReaderPage.jsx

@@ -6,6 +6,7 @@ import { bookOptions } from '../utils/bibleUtils.jsx';
 import { getPlan, getPlanSchedule, findDayIndexForRef, formatDayReadings, nextUnreadDayIndex, computeStreak, nearestReadingDay } from '../utils/readingPlans.js';
 import DrawCanvas from './DrawCanvas.jsx';
 import { READER_TRANSLATIONS } from '../utils/bibleText.js';
+import { useResizableWidth } from '../hooks/useResizableWidth.js';
 import { useParallelChapter } from '../hooks/useParallelChapter.js';
 import { useOfflineSave, useOnline } from '../hooks/useOfflineSave.js';
 import { useBibleSearch } from '../hooks/useBibleSearch.js';
@@ -108,6 +109,10 @@ export default function ReaderPage() {
   const [selectionPicker, setSelectionPicker] = useState(null);
   const [xrefRequest, setXrefRequest] = useState(null); // a cross-reference tapped in the text: { verse, ref, n }
   const swipeTouchRef = useRef(null);
+  // The side panel's width: drag its left edge (remembered on this device)
+  const rootRef = useRef(null);
+  const paneRef = useRef(null);
+  const pane = useResizableWidth({ storageKey: 'reader-pane-width', containerRef: rootRef, min: 320, maxAbsolute: 800, fallback: 384, reserve: 460, cssVar: '--reader-pane' });
   const readerPageInkStrokes = readerInkByPage?.[`${readerBookAbbrev}_${readerChapter}`] ?? NO_STROKES;
 
 
@@ -412,7 +417,7 @@ export default function ReaderPage() {
   const paneOpen = !!selectedVerse && !readerDrawMode;
 
   return (
-    <div className="min-h-dvh bg-[var(--r-bg)] text-[var(--r-text)]" style={themeVars(readerTheme)}
+    <div ref={rootRef} className="min-h-dvh bg-[var(--r-bg)] text-[var(--r-text)]" style={{ ...themeVars(readerTheme), ...(pane.width ? { '--reader-pane': `${pane.width}px` } : {}) }}
          onTouchStart={handleTouchStart} onTouchEnd={handleTouchEnd}>
       {chromeVisible && (
         <TopBar
@@ -452,7 +457,7 @@ export default function ReaderPage() {
         </p>
       )}
 
-      <div className={paneOpen ? 'lg:pr-[24rem]' : ''}>
+      <div className={paneOpen ? 'lg:pr-[var(--reader-pane,24rem)]' : ''}>
         {!readerDrawMode && (
           <ReaderText
             title={`${readerBook?.name ?? ''} ${readerChapter}`}
@@ -547,6 +552,14 @@ export default function ReaderPage() {
           onJump={jump}
           onClose={() => setReaderSelectedVerse(null)}
           request={xrefRequest}
+          panelRef={paneRef}
+          resizeHandle={(
+            // Drag this edge to resize (arrow keys too; double-click resets). Wide screens only.
+            <div {...pane.handleProps(paneRef)}
+              className="group absolute -left-1.5 top-0 z-20 hidden h-full w-3 cursor-col-resize touch-none select-none focus:outline-none lg:block">
+              <span className="mx-auto block h-full w-px bg-transparent transition group-hover:w-0.5 group-hover:bg-[var(--r-accent)] group-focus-visible:w-0.5 group-focus-visible:bg-[var(--r-accent)]" />
+            </div>
+          )}
           verseHighlights={verseHighlights} colorLabels={readerColorLabels ?? {}}
           onHighlightVerse={highlightVerse} onClearVerseHighlights={clearVerseHighlights}
         />

src/pages/ReaderPage.test.jsx

@@ -142,6 +142,18 @@ test('the H key opens the highlights', () => {
   expect(screen.getByRole('dialog', { name: /bookmarks & highlights/i })).toBeTruthy();
 });
 
+test('the side panel has a drag handle to resize it, and no handle when no verse is open', () => {
+  const saved = { ...ctx };
+  render(<ReaderPage />);
+  expect(screen.queryByRole('separator', { name: /resize side panel/i })).toBeNull();
+  Object.assign(ctx, { readerSelectedVerse: 1 });
+  render(<ReaderPage />);
+  const handle = screen.getByRole('separator', { name: /resize side panel/i });
+  expect(handle).toHaveAttribute('aria-orientation', 'vertical');
+  expect(handle).toHaveAttribute('tabindex', '0'); // reachable by keyboard (arrow keys resize)
+  Object.assign(ctx, saved);
+});
+
 test('tapping a verse selects it', () => {
   render(<ReaderPage />);
   fireEvent.click(screen.getByText(/This man came to Jesus/));