panels

frontend/src/app/DocumentsLayout.jsx

@@ -3,10 +3,11 @@ import Sidebar from '../sidebar/Sidebar';
 import { useSidebarContext } from '../sidebar/SidebarContext';
 
 const DocumentsLayout = ({ sidebarProps, children }) => {
-  const { collapsed } = useSidebarContext();
+  const { collapsed, sidebarSuppressed } = useSidebarContext();
+  const sidebarHidden = collapsed || sidebarSuppressed;
   return (
-    <main className={`documents-main${collapsed ? ' documents-main--sidebar-collapsed' : ''}`}>
-      {!collapsed ? <Sidebar {...sidebarProps} /> : null}
+    <main className={`documents-main${sidebarHidden ? ' documents-main--sidebar-hidden' : ''}`}>
+      {!sidebarHidden ? <Sidebar {...sidebarProps} /> : null}
       {children}
     </main>
   );

frontend/src/app/DocumentsRoute.jsx

@@ -1,4 +1,4 @@
-import React, { useCallback, useEffect, useMemo } from 'react';
+import React, { useCallback, useEffect, useMemo, useRef } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { useAppShell } from '../appShellContext';
 import DocumentsLayout from './DocumentsLayout';
@@ -28,9 +28,105 @@ const DocumentsRouteContent = () => {
     notifyApiError,
   } = useAppShell();
   const navigate = useNavigate();
-  const { collapsed: sidebarCollapsed, setCollapsed } = useSidebarContext();
+  const { collapsed: sidebarCollapsed, sidebarSuppressed, setCollapsed, setSidebarSuppressed } = useSidebarContext();
 
-  const expandSidebar = useCallback(() => setCollapsed(false), [setCollapsed]);
+  const getDetailPanelWidth = useCallback(() => {
+    if (typeof window === 'undefined') {
+      return null;
+    }
+    const panelEl = document.querySelector('.detail-panel');
+    if (panelEl) {
+      const rect = panelEl.getBoundingClientRect();
+      if (Number.isFinite(rect?.width)) {
+        return rect.width;
+      }
+    }
+    const rootStyles = window.getComputedStyle(document.documentElement);
+    const varValue = rootStyles.getPropertyValue('--detail-panel-width');
+    const parsed = parseFloat(varValue);
+    return Number.isFinite(parsed) ? parsed : null;
+  }, []);
+
+  const getSidebarWidth = useCallback(() => {
+    if (typeof window === 'undefined') {
+      return null;
+    }
+    const sidebarEl = document.querySelector('.sidebar');
+    if (sidebarEl) {
+      const rect = sidebarEl.getBoundingClientRect();
+      if (Number.isFinite(rect?.width)) {
+        return rect.width;
+      }
+    }
+    const rootStyles = window.getComputedStyle(document.documentElement);
+    const varValue = rootStyles.getPropertyValue('--sidebar-width');
+    const parsed = parseFloat(varValue);
+    return Number.isFinite(parsed) ? parsed : null;
+  }, []);
+
+  const shouldCloseDetailPanelForSidebar = useCallback(() => {
+    if (typeof window === 'undefined') {
+      return false;
+    }
+    if (!detailPanelOpen && !previewDocumentId) {
+      return false;
+    }
+    const detailWidth = getDetailPanelWidth();
+    const sidebarWidth = getSidebarWidth();
+    if (!Number.isFinite(detailWidth) || !Number.isFinite(sidebarWidth)) {
+      return false;
+    }
+    return detailWidth + sidebarWidth > window.innerWidth * (2 / 3);
+  }, [detailPanelOpen, previewDocumentId, getDetailPanelWidth, getSidebarWidth]);
+
+  const closeAnyDetailPanel = useCallback(() => {
+    if (previewDocumentId && typeof closeDocumentPreview === 'function') {
+      closeDocumentPreview();
+      return true;
+    }
+    if (detailPanelOpen && typeof detailPanelProps?.onClose === 'function') {
+      detailPanelProps.onClose();
+      return true;
+    }
+    return false;
+  }, [previewDocumentId, closeDocumentPreview, detailPanelOpen, detailPanelProps]);
+
+  const sidebarWidthRef = useRef(null);
+
+  useEffect(() => {
+    sidebarWidthRef.current = getSidebarWidth();
+  }, [getSidebarWidth]);
+
+  const expandSidebar = useCallback(() => {
+    if (shouldCloseDetailPanelForSidebar()) {
+      closeAnyDetailPanel();
+    }
+    setSidebarSuppressed(false);
+    setCollapsed(false);
+  }, [setCollapsed, setSidebarSuppressed, shouldCloseDetailPanelForSidebar, closeAnyDetailPanel]);
+
+  useEffect(() => {
+    if (typeof window === 'undefined') {
+      return undefined;
+    }
+    const handleSidebarResize = (event) => {
+      const nextWidth = Number.isFinite(event?.detail?.width)
+        ? event.detail.width
+        : getSidebarWidth();
+      const prevWidth = sidebarWidthRef.current;
+      if (Number.isFinite(nextWidth)) {
+        sidebarWidthRef.current = nextWidth;
+      }
+      if (Number.isFinite(nextWidth) && Number.isFinite(prevWidth) && nextWidth <= prevWidth) {
+        return;
+      }
+      if (shouldCloseDetailPanelForSidebar()) {
+        closeAnyDetailPanel();
+      }
+    };
+    window.addEventListener('sidebar-width-change', handleSidebarResize);
+    return () => window.removeEventListener('sidebar-width-change', handleSidebarResize);
+  }, [shouldCloseDetailPanelForSidebar, closeAnyDetailPanel, getSidebarWidth]);
 
   const sidebarPropsWithActions = useMemo(
     () => ({
@@ -67,8 +163,10 @@ const DocumentsRouteContent = () => {
     navigate(target);
   }, [navigate]);
 
+  const sidebarHidden = sidebarCollapsed || sidebarSuppressed;
+
   const { surface } = useWorkspaceSurface({
-    sidebarCollapsed,
+    sidebarHidden,
     onExpandSidebar: expandSidebar,
     documentsTableProps,
     detailPanelProps,

frontend/src/app/useWorkspaceSurface.js

@@ -5,7 +5,7 @@ import { createDocumentViewerSurface } from '../preview/DocumentViewerPanel';
 import createDesktopSurface from '../desktop/createDesktopSurface';
 
 export const useWorkspaceSurface = ({
-  sidebarCollapsed,
+  sidebarHidden,
   onExpandSidebar,
   documentsTableProps,
   detailPanelProps,
@@ -25,7 +25,7 @@ export const useWorkspaceSurface = ({
   onNavigateParent,
 }) => {
   const renderSidebarToggle = useCallback(() => {
-    if (!sidebarCollapsed) {
+    if (!sidebarHidden) {
       return null;
     }
     return (
@@ -39,7 +39,7 @@ export const useWorkspaceSurface = ({
         <SidebarExpandIcon />
       </button>
     );
-  }, [sidebarCollapsed, onExpandSidebar]);
+  }, [sidebarHidden, onExpandSidebar]);
 
   const documentsSurface = useMemo(() => {
     if (!documentsTableProps) {

frontend/src/preview/DocumentViewerPanel.jsx

@@ -26,6 +26,77 @@ import BreadcrumbTrail from '../ui/BreadcrumbTrail';
 import { useAssetNavigator } from '../hooks/useAssetNavigator';
 import DocumentViewerLayout from './DocumentViewerLayout';
 import useViewerLayoutMode from './useViewerLayoutMode';
+import { useSidebarContext } from '../sidebar/SidebarContext';
+
+const DETAIL_PANEL_WIDTH_STORAGE_KEY = 'detailPanelWidth';
+const MIN_DETAIL_PANEL_WIDTH = 320;
+const MAX_DETAIL_PANEL_WIDTH = 960;
+
+const isBrowser = typeof window !== 'undefined';
+const isDocumentAvailable = typeof document !== 'undefined';
+
+const getDetailPanelBounds = () => {
+  if (!isBrowser) {
+    return {
+      min: MIN_DETAIL_PANEL_WIDTH,
+      max: MAX_DETAIL_PANEL_WIDTH,
+    };
+  }
+  const viewportWidth = Math.max(window.innerWidth, 1);
+  const minFractionWidth = viewportWidth / 5;
+  const maxFractionWidth = viewportWidth * 0.75;
+  const rawMin = Math.max(MIN_DETAIL_PANEL_WIDTH, minFractionWidth);
+  const rawMax = Math.min(MAX_DETAIL_PANEL_WIDTH, maxFractionWidth);
+  if (rawMin >= rawMax) {
+    const fallback = Math.min(Math.max(rawMin, viewportWidth * 0.5), MAX_DETAIL_PANEL_WIDTH);
+    return { min: fallback, max: fallback };
+  }
+  return {
+    min: rawMin,
+    max: rawMax,
+  };
+};
+
+const clampDetailPanelWidth = (value) => {
+  if (!Number.isFinite(value) || value <= 0) {
+    return null;
+  }
+  const { min, max } = getDetailPanelBounds();
+  return Math.min(Math.max(value, min), max);
+};
+
+const loadStoredDetailPanelWidth = () => {
+  if (!isBrowser) {
+    return null;
+  }
+  try {
+    const raw = window.localStorage?.getItem(DETAIL_PANEL_WIDTH_STORAGE_KEY);
+    if (!raw) {
+      return null;
+    }
+    const parsed = parseInt(raw, 10);
+    return Number.isFinite(parsed) ? parsed : null;
+  } catch (error) {
+    console.warn('Failed to read detail panel width', error);
+    return null;
+  }
+};
+
+const applyDetailPanelWidth = (width) => {
+  if (!isDocumentAvailable || width == null) {
+    return;
+  }
+  document.documentElement.style.setProperty('--detail-panel-width', `${width}px`);
+};
+
+const getSidebarWidthFromRoot = () => {
+  if (!isBrowser || !isDocumentAvailable) {
+    return null;
+  }
+  const computed = window.getComputedStyle(document.documentElement);
+  const parsed = parseFloat(computed.getPropertyValue('--sidebar-width'));
+  return Number.isFinite(parsed) ? parsed : null;
+};
 
 export const createDocumentViewerHeaderActions = ({
   document,
@@ -99,6 +170,7 @@ const DocumentViewerPanel = ({
 }) => {
   const navigate = useNavigate();
   const isSidebarVariant = variant === 'sidebar';
+  const { setSidebarSuppressed } = useSidebarContext();
   const sortedCorrespondents = useMemo(
     () => sortCorrespondents(document?.correspondents || []),
     [document],
@@ -239,6 +311,174 @@ const DocumentViewerPanel = ({
 
   const panelRef = useRef(null);
   const isStackedLayout = useViewerLayoutMode(panelRef, document?.id);
+  const pendingWidthRef = useRef(null);
+  const [isResizingPanel, setIsResizingPanel] = useState(false);
+  const [detailPanelWidth, setDetailPanelWidth] = useState(() => {
+    if (!isBrowser) {
+      return null;
+    }
+    const stored = loadStoredDetailPanelWidth();
+    return stored != null ? clampDetailPanelWidth(stored) : null;
+  });
+
+  useEffect(() => {
+    if (detailPanelWidth != null) {
+      const clamped = clampDetailPanelWidth(detailPanelWidth);
+      if (clamped != null) {
+        applyDetailPanelWidth(clamped);
+      }
+    }
+  }, [detailPanelWidth]);
+
+  useEffect(() => {
+    if (!isSidebarVariant) {
+      setSidebarSuppressed(false);
+      return undefined;
+    }
+    const updateSuppression = () => {
+      if (!isBrowser) {
+        setSidebarSuppressed(false);
+        return;
+      }
+      const panelWidth = pendingWidthRef.current
+        ?? detailPanelWidth
+        ?? panelRef.current?.getBoundingClientRect().width;
+      const sidebarWidth = getSidebarWidthFromRoot();
+      if (!Number.isFinite(panelWidth)) {
+        setSidebarSuppressed(false);
+        return;
+      }
+      const minMainContentWidth = (window.innerWidth * 2) / 5;
+      const occupiedWidth = panelWidth + (Number.isFinite(sidebarWidth) ? sidebarWidth : 0);
+      const availableWidth = window.innerWidth - occupiedWidth;
+      setSidebarSuppressed(availableWidth < minMainContentWidth);
+    };
+
+    updateSuppression();
+    const handleWindowResize = () => updateSuppression();
+    window.addEventListener('resize', handleWindowResize);
+    return () => {
+      window.removeEventListener('resize', handleWindowResize);
+    };
+  }, [isSidebarVariant, detailPanelWidth, setSidebarSuppressed]);
+
+  useEffect(() => {
+    if (!isSidebarVariant) {
+      setSidebarSuppressed(false);
+    }
+  }, [isSidebarVariant, setSidebarSuppressed]);
+
+  useEffect(() => {
+    if (!isBrowser) {
+      return undefined;
+    }
+    const handleResize = () => {
+      setDetailPanelWidth((prev) => {
+        if (prev == null) {
+          return prev;
+        }
+        const clamped = clampDetailPanelWidth(prev);
+        if (clamped != null && clamped !== prev) {
+          applyDetailPanelWidth(clamped);
+          try {
+            window.localStorage?.setItem(DETAIL_PANEL_WIDTH_STORAGE_KEY, String(Math.round(clamped)));
+          } catch (error) {
+            console.warn('Failed to persist detail panel width', error);
+          }
+          return clamped;
+        }
+        return prev;
+      });
+    };
+    window.addEventListener('resize', handleResize);
+    return () => window.removeEventListener('resize', handleResize);
+  }, []);
+
+  const handleResizePointerDown = useCallback((event) => {
+    if (!isSidebarVariant || !panelRef.current || !isBrowser) {
+      return;
+    }
+    event.preventDefault();
+    event.stopPropagation();
+    const pointerId = event.pointerId;
+    const target = event.currentTarget;
+    target.setPointerCapture?.(pointerId);
+    setIsResizingPanel(true);
+
+    const rect = panelRef.current.getBoundingClientRect();
+    const startWidth = rect.width;
+    const startX = event.clientX;
+
+    const updateWidth = (nextWidth) => {
+      const clamped = clampDetailPanelWidth(nextWidth);
+      if (clamped != null) {
+        pendingWidthRef.current = clamped;
+        applyDetailPanelWidth(clamped);
+        if (isSidebarVariant && isBrowser) {
+          setSidebarSuppressed(clamped > window.innerWidth / 2);
+        }
+      }
+    };
+
+    const handlePointerMove = (moveEvent) => {
+      if (moveEvent.pointerId !== pointerId) {
+        return;
+      }
+      const delta = startX - moveEvent.clientX;
+      updateWidth(startWidth + delta);
+    };
+
+    const handlePointerUp = (upEvent) => {
+      if (upEvent.pointerId !== pointerId) {
+        return;
+      }
+      target.releasePointerCapture?.(pointerId);
+      window.removeEventListener('pointermove', handlePointerMove);
+      window.removeEventListener('pointerup', handlePointerUp);
+      setIsResizingPanel(false);
+      if (pendingWidthRef.current != null) {
+        const finalizedWidth = pendingWidthRef.current;
+        pendingWidthRef.current = null;
+        setDetailPanelWidth(finalizedWidth);
+        try {
+          window.localStorage?.setItem(DETAIL_PANEL_WIDTH_STORAGE_KEY, String(Math.round(finalizedWidth)));
+        } catch (error) {
+          console.warn('Failed to persist detail panel width', error);
+        }
+      }
+    };
+
+    window.addEventListener('pointermove', handlePointerMove);
+    window.addEventListener('pointerup', handlePointerUp);
+  }, [isSidebarVariant, setSidebarSuppressed]);
+
+  const handleResizeKeyDown = useCallback((event) => {
+    if (!isSidebarVariant || !isBrowser) {
+      return;
+    }
+    if (event.key !== 'ArrowLeft' && event.key !== 'ArrowRight') {
+      return;
+    }
+    const baseWidth = pendingWidthRef.current
+      ?? detailPanelWidth
+      ?? panelRef.current?.getBoundingClientRect().width;
+    if (!Number.isFinite(baseWidth)) {
+      return;
+    }
+    event.preventDefault();
+    const step = event.shiftKey ? 40 : 20;
+    const delta = event.key === 'ArrowLeft' ? step : -step;
+    const nextWidth = clampDetailPanelWidth(baseWidth + delta);
+    if (nextWidth == null) {
+      return;
+    }
+    setDetailPanelWidth(nextWidth);
+    try {
+      window.localStorage?.setItem(DETAIL_PANEL_WIDTH_STORAGE_KEY, String(Math.round(nextWidth)));
+    } catch (error) {
+      console.warn('Failed to persist detail panel width', error);
+    }
+  }, [detailPanelWidth, isSidebarVariant]);
 
   const viewerClassName = isStackedLayout
     ? 'document-viewer document-viewer--stacked'
@@ -403,6 +643,18 @@ const DocumentViewerPanel = ({
       )
     : null;
 
+  const resizeHandle = isSidebarVariant ? (
+    <button
+      type="button"
+      className={`detail-panel__resize-handle${isResizingPanel ? ' is-active' : ''}`}
+      aria-label="Resize detail panel"
+      onPointerDown={handleResizePointerDown}
+      onKeyDown={handleResizeKeyDown}
+    >
+      <span aria-hidden="true" />
+    </button>
+  ) : null;
+
   const loadingSection = (
     <div className="document-viewer-panel__body">
       <section className="document-viewer document-viewer--loading">
@@ -460,7 +712,8 @@ const DocumentViewerPanel = ({
   if (isSidebarVariant) {
     return (
       <>
-        <aside className="detail-panel panel" ref={panelRef}>
+        <aside className={`detail-panel panel${isResizingPanel ? ' detail-panel--resizing' : ''}`} ref={panelRef}>
+          {resizeHandle}
           <PanelHeader
             leading={headerLeadingContent}
             title={headerTitle}

frontend/src/preview/useViewerLayoutMode.js

@@ -1,6 +1,5 @@
 import { useLayoutEffect, useState } from 'react';
 
-const PORTRAIT_WIDTH_TO_HEIGHT = 1 / Math.sqrt(2); // ≈0.707 (A-series aspect ratio)
 export const DOCUMENT_VIEWER_PORTRAIT_HEIGHT_RATIO = 0.4;
 const PORTRAIT_RATIO_STYLE_ID = 'document-viewer-portrait-ratio-style';
 
@@ -25,14 +24,10 @@ const ensurePortraitRatioStyle = () => {
 };
 
 const computeStackedLayoutBreakpoint = () => {
-  const viewportHeight = typeof window !== 'undefined' ? window.innerHeight : 900;
-  const portraitViewportWidth = viewportHeight
-    * DOCUMENT_VIEWER_PORTRAIT_HEIGHT_RATIO
-    * PORTRAIT_WIDTH_TO_HEIGHT;
-  const detailsColumnWidth = 320; // px ~ 20rem for metadata & tabs
-  const gutterAllowance = 48; // padding + grid gap
-
-  return portraitViewportWidth + detailsColumnWidth + gutterAllowance;
+  if (typeof window === 'undefined') {
+    return 900;
+  }
+  return window.innerWidth / 2;
 };
 
 export const useViewerLayoutMode = (ref, dependency) => {

frontend/src/sidebar/Sidebar.jsx

@@ -1,4 +1,4 @@
-import React, { useCallback, useEffect, useMemo, useRef, useId } from 'react';
+import React, { useCallback, useEffect, useMemo, useRef, useState, useId } from 'react';
 import { createPortal } from 'react-dom';
 import {
   ChevronIcon,
@@ -24,6 +24,80 @@ import useFloatingMenu from '../ui/useFloatingMenu';
 import { getTagColorStyle } from '../utils/colors';
 import { useSidebarContext } from './SidebarContext';
 
+const SIDEBAR_WIDTH_STORAGE_KEY = 'documentsSidebarWidth';
+const SIDEBAR_WIDTH_EVENT = 'sidebar-width-change';
+const MIN_SIDEBAR_WIDTH = 240;
+const MAX_SIDEBAR_WIDTH = 640;
+const isBrowser = typeof window !== 'undefined';
+const isDocumentAvailable = typeof document !== 'undefined';
+
+const notifySidebarWidthChange = (width) => {
+  if (!isBrowser) {
+    return;
+  }
+  try {
+    window.dispatchEvent(
+      new CustomEvent(SIDEBAR_WIDTH_EVENT, {
+        detail: { width },
+      }),
+    );
+  } catch (error) {
+    console.warn('Failed to dispatch sidebar width change', error);
+  }
+};
+
+const getSidebarBounds = () => {
+  if (!isBrowser) {
+    return {
+      min: MIN_SIDEBAR_WIDTH,
+      max: MAX_SIDEBAR_WIDTH,
+    };
+  }
+  const viewportWidth = Math.max(window.innerWidth, 1);
+  const minFractionWidth = viewportWidth / 6;
+  const maxFractionWidth = viewportWidth / 3;
+  const rawMin = Math.max(MIN_SIDEBAR_WIDTH, minFractionWidth);
+  const rawMax = Math.min(MAX_SIDEBAR_WIDTH, maxFractionWidth);
+  if (rawMin >= rawMax) {
+    const fallback = Math.min(Math.max(rawMin, viewportWidth / 4), MAX_SIDEBAR_WIDTH);
+    return { min: fallback, max: fallback };
+  }
+  return { min: rawMin, max: rawMax };
+};
+
+const clampSidebarWidth = (value) => {
+  if (!Number.isFinite(value) || value <= 0) {
+    return null;
+  }
+  const { min, max } = getSidebarBounds();
+  return Math.min(Math.max(value, min), max);
+};
+
+const loadStoredSidebarWidth = () => {
+  if (!isBrowser) {
+    return null;
+  }
+  try {
+    const raw = window.localStorage?.getItem(SIDEBAR_WIDTH_STORAGE_KEY);
+    if (!raw) {
+      return null;
+    }
+    const parsed = parseInt(raw, 10);
+    return Number.isFinite(parsed) ? parsed : null;
+  } catch (error) {
+    console.warn('Failed to read sidebar width', error);
+    return null;
+  }
+};
+
+const applySidebarWidth = (width) => {
+  if (!isDocumentAvailable || width == null) {
+    return;
+  }
+  document.documentElement.style.setProperty('--sidebar-width', `${width}px`);
+  notifySidebarWidthChange(width);
+};
+
 const FolderNode = ({
   node,
   depth,
@@ -204,8 +278,137 @@ const Sidebar = ({
     themeMode,
     cycleThemeMode,
     themeModes,
+    sidebarSuppressed,
   } = useSidebarContext();
   const uploadInputRef = useRef(null);
+  const sidebarRef = useRef(null);
+  const pendingWidthRef = useRef(null);
+  const [isResizingSidebar, setIsResizingSidebar] = useState(false);
+  const [sidebarWidthState, setSidebarWidthState] = useState(() => {
+    if (!isBrowser) {
+      return null;
+    }
+    const stored = loadStoredSidebarWidth();
+    return stored != null ? clampSidebarWidth(stored) : null;
+  });
+
+  useEffect(() => {
+    if (sidebarWidthState != null) {
+      const clamped = clampSidebarWidth(sidebarWidthState);
+      if (clamped != null) {
+        applySidebarWidth(clamped);
+      }
+    }
+  }, [sidebarWidthState]);
+
+  useEffect(() => {
+    if (!isBrowser) {
+      return undefined;
+    }
+    const handleResize = () => {
+      setSidebarWidthState((prev) => {
+        if (prev == null) {
+          return prev;
+        }
+        const clamped = clampSidebarWidth(prev);
+        if (clamped != null && clamped !== prev) {
+          applySidebarWidth(clamped);
+          try {
+            window.localStorage?.setItem(SIDEBAR_WIDTH_STORAGE_KEY, String(Math.round(clamped)));
+          } catch (error) {
+            console.warn('Failed to persist sidebar width', error);
+          }
+          return clamped;
+        }
+        return prev;
+      });
+    };
+    window.addEventListener('resize', handleResize);
+    return () => window.removeEventListener('resize', handleResize);
+  }, []);
+
+  const handleSidebarResizePointerDown = useCallback((event) => {
+    if (!isBrowser || !sidebarRef.current) {
+      return;
+    }
+    event.preventDefault();
+    event.stopPropagation();
+    const pointerId = event.pointerId;
+    const target = event.currentTarget;
+    target.setPointerCapture?.(pointerId);
+    setIsResizingSidebar(true);
+
+    const rect = sidebarRef.current.getBoundingClientRect();
+    const startWidth = rect.width;
+    const startX = event.clientX;
+
+    const updateWidth = (nextWidth) => {
+      const clamped = clampSidebarWidth(nextWidth);
+      if (clamped != null) {
+        pendingWidthRef.current = clamped;
+        applySidebarWidth(clamped);
+      }
+    };
+
+    const handlePointerMove = (moveEvent) => {
+      if (moveEvent.pointerId !== pointerId) {
+        return;
+      }
+      const delta = moveEvent.clientX - startX;
+      updateWidth(startWidth + delta);
+    };
+
+    const handlePointerUp = (upEvent) => {
+      if (upEvent.pointerId !== pointerId) {
+        return;
+      }
+      target.releasePointerCapture?.(pointerId);
+      window.removeEventListener('pointermove', handlePointerMove);
+      window.removeEventListener('pointerup', handlePointerUp);
+      setIsResizingSidebar(false);
+      if (pendingWidthRef.current != null) {
+        const finalizedWidth = pendingWidthRef.current;
+        pendingWidthRef.current = null;
+        setSidebarWidthState(finalizedWidth);
+        try {
+          window.localStorage?.setItem(SIDEBAR_WIDTH_STORAGE_KEY, String(Math.round(finalizedWidth)));
+        } catch (error) {
+          console.warn('Failed to persist sidebar width', error);
+        }
+      }
+    };
+
+    window.addEventListener('pointermove', handlePointerMove);
+    window.addEventListener('pointerup', handlePointerUp);
+  }, []);
+
+  const handleSidebarResizeKeyDown = useCallback((event) => {
+    if (!isBrowser) {
+      return;
+    }
+    if (event.key !== 'ArrowLeft' && event.key !== 'ArrowRight') {
+      return;
+    }
+    const baseWidth = pendingWidthRef.current
+      ?? sidebarWidthState
+      ?? sidebarRef.current?.getBoundingClientRect().width;
+    if (!Number.isFinite(baseWidth)) {
+      return;
+    }
+    event.preventDefault();
+    const step = event.shiftKey ? 40 : 20;
+    const delta = event.key === 'ArrowRight' ? step : -step;
+    const nextWidth = clampSidebarWidth(baseWidth + delta);
+    if (nextWidth == null) {
+      return;
+    }
+    setSidebarWidthState(nextWidth);
+    try {
+      window.localStorage?.setItem(SIDEBAR_WIDTH_STORAGE_KEY, String(Math.round(nextWidth)));
+    } catch (error) {
+      console.warn('Failed to persist sidebar width', error);
+    }
+  }, [sidebarWidthState]);
   const handleCollapse = useCallback(() => {
     setCollapsed(true);
   }, [setCollapsed]);
@@ -547,8 +750,25 @@ const Sidebar = ({
   );
 
   const rootNode = folderNodes.get('root');
+  const sidebarClassNames = ['sidebar'];
+  if (isResizingSidebar) {
+    sidebarClassNames.push('sidebar--resizing');
+  }
+  if (sidebarSuppressed) {
+    sidebarClassNames.push('sidebar--suppressed');
+  }
+
   return (
-    <aside className="sidebar">
+    <aside className={sidebarClassNames.join(' ')} ref={sidebarRef}>
+      <button
+        type="button"
+        className={`sidebar__resize-handle${isResizingSidebar ? ' is-active' : ''}`}
+        aria-label="Resize sidebar"
+        onPointerDown={handleSidebarResizePointerDown}
+        onKeyDown={handleSidebarResizeKeyDown}
+      >
+        <span aria-hidden="true" />
+      </button>
       <input
         type="file"
         ref={uploadInputRef}

frontend/src/sidebar/SidebarContext.js

@@ -139,6 +139,7 @@ const loadInitialCollapsedState = (defaultValue) => {
 
 export const SidebarProvider = ({ initialCollapsed = false, children }) => {
   const [collapsed, setCollapsedState] = useState(() => loadInitialCollapsedState(initialCollapsed));
+  const [sidebarSuppressedState, setSidebarSuppressedState] = useState(false);
   const initialTheme = useMemo(() => loadInitialThemeSettings(), []);
   const [neutralHue, setNeutralHueState] = useState(initialTheme.neutralHue);
   const [neutralChroma, setNeutralChromaState] = useState(initialTheme.neutralChroma);
@@ -283,10 +284,20 @@ export const SidebarProvider = ({ initialCollapsed = false, children }) => {
     setCollapsedState(Boolean(value));
   }, []);
 
+  const setSidebarSuppressed = useCallback((value) => {
+    if (typeof value === 'function') {
+      setSidebarSuppressedState((prev) => Boolean(value(prev)));
+      return;
+    }
+    setSidebarSuppressedState(Boolean(value));
+  }, []);
+
   const contextValue = useMemo(
     () => ({
       collapsed,
       setCollapsed,
+      sidebarSuppressed: sidebarSuppressedState,
+      setSidebarSuppressed,
       neutralHue,
       setNeutralHue,
       neutralChroma,
@@ -307,6 +318,8 @@ export const SidebarProvider = ({ initialCollapsed = false, children }) => {
     [
       collapsed,
       setCollapsed,
+      sidebarSuppressedState,
+      setSidebarSuppressed,
       neutralHue,
       setNeutralHue,
       neutralChroma,
@@ -334,8 +347,11 @@ export const useSidebarContext = () => {
 };
 
 export const useSidebarControls = () => {
-  const { setCollapsed } = useSidebarContext();
-  const openSidebar = useCallback(() => setCollapsed(false), [setCollapsed]);
+  const { setCollapsed, setSidebarSuppressed } = useSidebarContext();
+  const openSidebar = useCallback(() => {
+    setSidebarSuppressed(false);
+    setCollapsed(false);
+  }, [setCollapsed, setSidebarSuppressed]);
   const closeSidebar = useCallback(() => setCollapsed(true), [setCollapsed]);
   return { openSidebar, closeSidebar };
 };

frontend/src/styles/base/theme.css

@@ -101,6 +101,7 @@
   --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
 
   --detail-panel-width: calc(100vw / 3);
+  --sidebar-width: 20em;
   --documents-grid-title-size: 0.8rem;
 }
 

frontend/src/styles/detail/detail-panels.css

@@ -12,6 +12,48 @@
   display: flex;
   flex-direction: column;
   z-index: 1000000;
+  overflow: visible;
+}
+
+.detail-panel--resizing {
+  cursor: col-resize;
+  user-select: none;
+}
+
+.detail-panel__resize-handle {
+  position: absolute;
+  top: 0;
+  left: -0.4rem;
+  width: 0.8rem;
+  height: 100%;
+  border: none;
+  background: transparent;
+  padding: 0;
+  margin: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: col-resize;
+}
+
+.detail-panel__resize-handle span {
+  width: 2px;
+  height: 32px;
+  border-radius: 999px;
+  background: transparent;
+  transition: background 120ms ease;
+}
+
+.detail-panel__resize-handle:hover span,
+.detail-panel__resize-handle:focus-visible span,
+.detail-panel__resize-handle.is-active span {
+  background: var(--accent);
+}
+
+.detail-panel__resize-handle:focus-visible {
+  outline: 2px solid color-mix(in oklch, var(--accent) 60%, transparent);
+  outline-offset: 2px;
+  border-radius: 999px;
 }
 
 .panel-header {

frontend/src/styles/documents/listing.css

@@ -79,7 +79,7 @@
   justify-content: center;
   flex-wrap: nowrap;
   gap: 0.75rem;
-  z-index: 2000000;
+  z-index: 950000;
 }
 
 .panel-floating__label {

frontend/src/styles/layout/structure.css

@@ -14,7 +14,7 @@
   position: relative;
 }
 
-.documents-main--sidebar-collapsed {
+.documents-main--sidebar-hidden {
   position: relative;
 }
 
@@ -30,7 +30,7 @@
   box-shadow: -12px 0 24px -12px var(--shadow-faint);
 }
 
-.documents-main:not(.documents-main--sidebar-collapsed) .main-content {
+.documents-main:not(.documents-main--sidebar-hidden) .main-content {
   border-left: 1px solid var(--border);
 }
 
@@ -77,7 +77,7 @@
 }
 
 
-.documents-main--sidebar-collapsed {
+.documents-main--sidebar-hidden {
   position: relative;
   grid-template-columns: auto minmax(0, 1fr);
 }

frontend/src/styles/sidebar/sidebar.css

@@ -128,10 +128,53 @@
   color: var(--sidebar-fg);
   display: flex;
   flex-direction: column;
-  width: 20em;
-  max-width: 20em;
-  flex: 0 0 20em;
+  width: min(100vw, var(--sidebar-width));
+  max-width: min(100vw, var(--sidebar-width));
+  flex: 0 0 var(--sidebar-width);
   background: var(--bg);
+  position: relative;
+}
+
+.sidebar--resizing {
+  cursor: col-resize;
+  user-select: none;
+}
+
+.sidebar__resize-handle {
+  position: absolute;
+  top: 0;
+  right: -0.4rem;
+  width: 0.8rem;
+  height: 100%;
+  border: none;
+  background: transparent;
+  padding: 0;
+  margin: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: col-resize;
+  z-index: 1;
+}
+
+.sidebar__resize-handle span {
+  width: 2px;
+  height: 32px;
+  border-radius: 999px;
+  background: transparent;
+  transition: background 120ms ease;
+}
+
+.sidebar__resize-handle:hover span,
+.sidebar__resize-handle:focus-visible span,
+.sidebar__resize-handle.is-active span {
+  background: var(--accent);
+}
+
+.sidebar__resize-handle:focus-visible {
+  outline: 2px solid color-mix(in oklch, var(--accent) 60%, transparent);
+  outline-offset: 2px;
+  border-radius: 999px;
 }
 
 .sidebar__body {