diff --git a/apps/web/app/page-client.tsx b/apps/web/app/page-client.tsx
index 0dfc5e7036..5278029402 100644
--- a/apps/web/app/page-client.tsx
+++ b/apps/web/app/page-client.tsx
@@ -2,7 +2,7 @@
 
 import { useState } from 'react';
 
-import { KanbanBoard } from '@/components/kanban-board';
+import { KanbanWithPreview } from '@/components/kanban-with-preview';
 import { OnboardingDialog } from '@/components/onboarding-dialog';
 import { getLocalStorage, setLocalStorage } from '@/lib/local-storage';
 import { STORAGE_KEYS } from '@/lib/settings/constants';
@@ -24,7 +24,7 @@ export function PageClient() {
   return (
     <>
       <OnboardingDialog open={showOnboarding} onComplete={handleOnboardingComplete} />
-      <KanbanBoard key={boardKey} />
+      <KanbanWithPreview key={boardKey} />
     </>
   );
 }
diff --git a/apps/web/components/kanban-board-grid.tsx b/apps/web/components/kanban-board-grid.tsx
index d42fe70b1e..3db79df4eb 100644
--- a/apps/web/components/kanban-board-grid.tsx
+++ b/apps/web/components/kanban-board-grid.tsx
@@ -15,6 +15,7 @@ import { KanbanCardPreview, Task } from './kanban-card';
 export type KanbanBoardGridProps = {
   columns: Column[];
   tasks: Task[];
+  onPreviewTask: (task: Task) => void;
   onOpenTask: (task: Task) => void;
   onEditTask: (task: Task) => void;
   onDeleteTask: (task: Task) => void;
@@ -27,6 +28,7 @@ export type KanbanBoardGridProps = {
 export function KanbanBoardGrid({
   columns,
   tasks,
+  onPreviewTask,
   onOpenTask,
   onEditTask,
   onDeleteTask,
@@ -72,6 +74,7 @@ export function KanbanBoardGrid({
                 key={column.id}
                 column={column}
                 tasks={getTasksForColumn(column.id)}
+                onPreviewTask={onPreviewTask}
                 onOpenTask={onOpenTask}
                 onEditTask={onEditTask}
                 onDeleteTask={onDeleteTask}
diff --git a/apps/web/components/kanban-board.tsx b/apps/web/components/kanban-board.tsx
index 041c428fa3..fd3be48383 100644
--- a/apps/web/components/kanban-board.tsx
+++ b/apps/web/components/kanban-board.tsx
@@ -16,7 +16,12 @@ import { useTaskActions } from '@/hooks/use-task-actions';
 import { KanbanBoardHeader } from './kanban-board-header';
 import { KanbanBoardGrid } from './kanban-board-grid';
 
-export function KanbanBoard() {
+interface KanbanBoardProps {
+  onPreviewTask?: (task: Task) => void;
+  onOpenTask?: (task: Task) => void;
+}
+
+export function KanbanBoard({ onPreviewTask, onOpenTask }: KanbanBoardProps = {}) {
   const [isDialogOpen, setIsDialogOpen] = useState(false);
   const [activeTaskId, setActiveTaskId] = useState<string | null>(null);
   const [isMovingTask, setIsMovingTask] = useState(false);
@@ -192,7 +197,20 @@ export function KanbanBoard() {
   };
 
   const handleOpenTask = (task: Task) => {
-    router.push(`/task/${task.id}`);
+    if (onOpenTask) {
+      onOpenTask(task);
+    } else {
+      router.push(`/task/${task.id}`);
+    }
+  };
+
+  const handlePreviewTask = (task: Task) => {
+    if (onPreviewTask) {
+      onPreviewTask(task);
+    } else {
+      // Fallback to opening full page if no preview handler
+      handleOpenTask(task);
+    }
   };
 
   const handleEditTask = (task: Task) => {
@@ -358,6 +376,7 @@ export function KanbanBoard() {
       <KanbanBoardGrid
         columns={activeColumns}
         tasks={visibleTasks}
+        onPreviewTask={handlePreviewTask}
         onOpenTask={handleOpenTask}
         onEditTask={handleEditTask}
         onDeleteTask={handleDeleteTask}
diff --git a/apps/web/components/kanban-card.tsx b/apps/web/components/kanban-card.tsx
index c73c194f33..76d1115e94 100644
--- a/apps/web/components/kanban-card.tsx
+++ b/apps/web/components/kanban-card.tsx
@@ -2,7 +2,7 @@
 
 import { useDraggable } from '@dnd-kit/core';
 import { CSS } from '@dnd-kit/utilities';
-import { IconAlertTriangle, IconCircleCheck, IconCircleX, IconDots, IconLoader2 } from '@tabler/icons-react';
+import { IconAlertTriangle, IconCircleCheck, IconCircleX, IconDots, IconLoader2, IconArrowsMaximize } from '@tabler/icons-react';
 import { Card, CardContent } from '@kandev/ui/card';
 import {
   DropdownMenu,
@@ -29,6 +29,7 @@ interface KanbanCardProps {
   onClick?: (task: Task) => void;
   onEdit?: (task: Task) => void;
   onDelete?: (task: Task) => void;
+  onOpenFullPage?: (task: Task) => void;
 }
 
 function KanbanCardBody({
@@ -77,7 +78,7 @@ function KanbanCardLayout({ task, className }: KanbanCardProps & { className?: s
   );
 }
 
-export function KanbanCard({ task, onClick, onEdit, onDelete }: KanbanCardProps) {
+export function KanbanCard({ task, onClick, onEdit, onDelete, onOpenFullPage }: KanbanCardProps) {
   const { attributes, listeners, setNodeRef, transform, isDragging } = useDraggable({
     id: task.id,
   });
@@ -137,13 +138,29 @@ export function KanbanCard({ task, onClick, onEdit, onDelete }: KanbanCardProps)
           actions={
             <div className="flex items-center gap-2">
               {statusIcon}
+              {onOpenFullPage && (
+                <button
+                  type="button"
+                  className="text-muted-foreground hover:text-foreground hover:bg-accent rounded-sm p-1 -m-1 transition-colors cursor-pointer"
+                  onClick={(event) => {
+                    event.stopPropagation();
+                    onOpenFullPage(task);
+                  }}
+                  onPointerDown={(event) => event.stopPropagation()}
+                  aria-label="Open full page"
+                  title="Open full page"
+                >
+                  <IconArrowsMaximize className="h-4 w-4" />
+                </button>
+              )}
               <DropdownMenu>
                 <DropdownMenuTrigger asChild>
                   <button
                     type="button"
-                    className="text-muted-foreground hover:text-foreground cursor-pointer"
+                    className="text-muted-foreground hover:text-foreground hover:bg-muted rounded-sm p-1 -m-1 transition-colors cursor-pointer"
                     onClick={(event) => event.stopPropagation()}
                     onPointerDown={(event) => event.stopPropagation()}
+                    aria-label="More options"
                   >
                     <IconDots className="h-4 w-4" />
                   </button>
diff --git a/apps/web/components/kanban-column.tsx b/apps/web/components/kanban-column.tsx
index 0955bb8b06..6d88beb6a1 100644
--- a/apps/web/components/kanban-column.tsx
+++ b/apps/web/components/kanban-column.tsx
@@ -14,12 +14,13 @@ export interface Column {
 interface KanbanColumnProps {
   column: Column;
   tasks: Task[];
+  onPreviewTask: (task: Task) => void;
   onOpenTask: (task: Task) => void;
   onEditTask: (task: Task) => void;
   onDeleteTask: (task: Task) => void;
 }
 
-export function KanbanColumn({ column, tasks, onOpenTask, onEditTask, onDeleteTask }: KanbanColumnProps) {
+export function KanbanColumn({ column, tasks, onPreviewTask, onOpenTask, onEditTask, onDeleteTask }: KanbanColumnProps) {
   const { setNodeRef, isOver } = useDroppable({
     id: column.id,
   });
@@ -52,7 +53,8 @@ export function KanbanColumn({ column, tasks, onOpenTask, onEditTask, onDeleteTa
             <KanbanCard
               key={task.id}
               task={task}
-              onClick={onOpenTask}
+              onClick={onPreviewTask}
+              onOpenFullPage={onOpenTask}
               onEdit={onEditTask}
               onDelete={onDeleteTask}
             />
diff --git a/apps/web/components/kanban-with-preview.tsx b/apps/web/components/kanban-with-preview.tsx
new file mode 100644
index 0000000000..542dba75d9
--- /dev/null
+++ b/apps/web/components/kanban-with-preview.tsx
@@ -0,0 +1,242 @@
+"use client";
+
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { useRouter } from "next/navigation";
+import { KanbanBoard } from "./kanban-board";
+import { TaskPreviewPanel } from "./task-preview-panel";
+import { useKanbanPreview } from "@/hooks/use-kanban-preview";
+import { useAppStore } from "@/components/state-provider";
+import { Task } from "./kanban-card";
+import { PREVIEW_PANEL } from "@/lib/settings/constants";
+
+export function KanbanWithPreview() {
+  const router = useRouter();
+  const containerRef = useRef<HTMLDivElement>(null);
+  const [containerWidth, setContainerWidth] = useState<number>(0);
+  const isResizingRef = useRef(false);
+
+  // Get tasks from the kanban store
+  const kanbanTasks = useAppStore((state) => state.kanban.tasks);
+
+  const {
+    selectedTaskId,
+    isOpen,
+    previewWidthPx,
+    open,
+    close,
+    updatePreviewWidth,
+  } = useKanbanPreview({
+    onClose: () => {
+      // Cleanup handled by close
+    },
+  });
+
+  // Compute selected task from kanbanTasks and selectedTaskId
+  const selectedTask = useMemo(() => {
+    if (!selectedTaskId || kanbanTasks.length === 0) return null;
+
+    const task = kanbanTasks.find((t) => t.id === selectedTaskId);
+    if (!task) return null;
+
+    return {
+      id: task.id,
+      title: task.title,
+      columnId: task.columnId,
+      state: task.state,
+      description: task.description,
+      position: task.position,
+      repositoryUrl: task.repositoryUrl,
+    };
+  }, [selectedTaskId, kanbanTasks]);
+
+  // Measure container width on mount and resize
+  useEffect(() => {
+    if (!containerRef.current) return;
+
+    const updateWidth = () => {
+      if (containerRef.current) {
+        setContainerWidth(containerRef.current.offsetWidth);
+      }
+    };
+
+    updateWidth();
+    const resizeObserver = new ResizeObserver(updateWidth);
+    resizeObserver.observe(containerRef.current);
+
+    return () => {
+      resizeObserver.disconnect();
+    };
+  }, []);
+
+  // Calculate if we should be in floating mode
+  // Float when preview would make kanban less than minimum percentage
+  const minKanbanWidthPx = (PREVIEW_PANEL.MIN_KANBAN_WIDTH_PERCENT / 100) * containerWidth;
+  const availableForKanban = containerWidth - previewWidthPx;
+  const shouldFloat = isOpen && containerWidth > 0 && availableForKanban < minKanbanWidthPx;
+
+  // Close panel if selected task no longer exists
+  useEffect(() => {
+    if (isOpen && selectedTaskId && !selectedTask) {
+      close();
+    }
+  }, [isOpen, selectedTaskId, selectedTask, close]);
+
+  const handleNavigateToTask = useCallback(
+    (task: Task) => {
+      close();
+      router.push(`/task/${task.id}`);
+    },
+    [close, router]
+  );
+
+  // Preview handler - task data is computed from selectedTaskId
+  // Toggle behavior: clicking the same task closes the panel
+  const handlePreviewTaskWithData = useCallback(
+    (task: Task) => {
+      if (isOpen && selectedTaskId === task.id) {
+        close();
+      } else {
+        open(task.id);
+      }
+    },
+    [isOpen, selectedTaskId, open, close]
+  );
+
+  // Handle Escape key to close preview
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (e.key === "Escape" && isOpen) {
+        close();
+      }
+    };
+
+    window.addEventListener("keydown", handleKeyDown);
+    return () => window.removeEventListener("keydown", handleKeyDown);
+  }, [isOpen, close]);
+
+  // Unified resize handler for both inline and floating modes
+  const handleResizeMouseDown = useCallback((e: React.MouseEvent) => {
+    e.preventDefault();
+    isResizingRef.current = true;
+
+    const startX = e.clientX;
+    const startWidth = previewWidthPx;
+
+    const handleMouseMove = (moveEvent: MouseEvent) => {
+      if (!isResizingRef.current) return;
+
+      // Calculate new width (moving left increases width)
+      const deltaX = startX - moveEvent.clientX;
+      const newWidth = startWidth + deltaX;
+
+      // No maximum limit - can resize all the way to the left
+      // updatePreviewWidth enforces minimum width
+      updatePreviewWidth(newWidth);
+    };
+
+    const handleMouseUp = () => {
+      isResizingRef.current = false;
+      window.removeEventListener("mousemove", handleMouseMove);
+      window.removeEventListener("mouseup", handleMouseUp);
+    };
+
+    window.addEventListener("mousemove", handleMouseMove);
+    window.addEventListener("mouseup", handleMouseUp);
+  }, [previewWidthPx, updatePreviewWidth]);
+
+  // Calculate kanban width - keep it at min width when floating to avoid repainting
+  const kanbanWidth = shouldFloat
+    ? minKanbanWidthPx
+    : (isOpen ? containerWidth - previewWidthPx : containerWidth);
+
+  return (
+    <div ref={containerRef} className="h-screen w-full flex flex-col bg-background relative">
+      {shouldFloat ? (
+        // Floating mode: kanban at min width, preview overlays
+        <>
+          <div
+            className="flex-1 overflow-hidden"
+            style={{
+              width: `${kanbanWidth}px`,
+            }}
+          >
+            <KanbanBoard
+              onPreviewTask={handlePreviewTaskWithData}
+              onOpenTask={handleNavigateToTask}
+            />
+          </div>
+
+          {/* Backdrop */}
+          <div
+            className="fixed inset-0 bg-black/30 z-30"
+            onClick={close}
+            aria-label="Close preview"
+          />
+
+          {/* Floating Panel */}
+          <div
+            className="fixed right-0 top-0 bottom-0 z-40 shadow-2xl bg-background flex"
+            style={{
+              width: `${previewWidthPx}px`,
+              maxWidth: `${PREVIEW_PANEL.MAX_WIDTH_VW}vw`,
+            }}
+          >
+            {/* Resize handle on the left edge */}
+            <div
+              className="w-1 bg-border hover:bg-primary cursor-col-resize flex-shrink-0 relative group"
+              onMouseDown={handleResizeMouseDown}
+            >
+              <div className="absolute inset-y-0 -left-2 -right-2" />
+              <div className="absolute top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 w-1 h-8 bg-border group-hover:bg-primary rounded-full transition-colors" />
+            </div>
+
+            {/* Panel content */}
+            <div className="flex-1 min-w-0 overflow-hidden">
+              <TaskPreviewPanel task={selectedTask} onClose={close} onMaximize={handleNavigateToTask} />
+            </div>
+          </div>
+        </>
+      ) : (
+        // Inline mode: side by side with custom resize
+        <div className="flex-1 flex overflow-hidden">
+          {/* Kanban Board */}
+          <div
+            className="overflow-hidden"
+            style={{
+              width: `${kanbanWidth}px`,
+            }}
+          >
+            <KanbanBoard
+              onPreviewTask={handlePreviewTaskWithData}
+              onOpenTask={handleNavigateToTask}
+            />
+          </div>
+
+          {/* Preview Panel */}
+          {isOpen && (
+            <div
+              className="flex-shrink-0 border-l bg-background flex"
+              style={{
+                width: `${previewWidthPx}px`,
+              }}
+            >
+              {/* Resize handle */}
+              <div
+                className="w-1 bg-border hover:bg-primary cursor-col-resize flex-shrink-0 relative group"
+                onMouseDown={handleResizeMouseDown}
+              >
+                <div className="absolute inset-y-0 -left-2 -right-2" />
+                <div className="absolute top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 w-1 h-8 bg-border group-hover:bg-primary rounded-full transition-colors" />
+              </div>
+
+              {/* Panel content */}
+              <div className="flex-1 min-w-0 overflow-hidden">
+                <TaskPreviewPanel task={selectedTask} onClose={close} onMaximize={handleNavigateToTask} />
+              </div>
+            </div>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}
diff --git a/apps/web/components/task-preview-panel.tsx b/apps/web/components/task-preview-panel.tsx
new file mode 100644
index 0000000000..8c90383c04
--- /dev/null
+++ b/apps/web/components/task-preview-panel.tsx
@@ -0,0 +1,155 @@
+"use client";
+
+import { IconX, IconCircleCheck, IconCircleX, IconLoader2, IconAlertTriangle, IconArrowsMaximize } from "@tabler/icons-react";
+import { Button } from "@kandev/ui/button";
+import { Badge } from "@kandev/ui/badge";
+import { getRepositoryDisplayName } from "@/lib/utils";
+import type { Task } from "./kanban-card";
+
+interface TaskPreviewPanelProps {
+  task: Task | null;
+  onClose: () => void;
+  onMaximize?: (task: Task) => void;
+}
+
+function getStateDisplay(state?: string) {
+  switch (state) {
+    case "IN_PROGRESS":
+    case "SCHEDULING":
+      return {
+        label: state === "SCHEDULING" ? "Scheduling" : "In Progress",
+        icon: <IconLoader2 className="h-3 w-3 animate-spin" />,
+        variant: "default" as const,
+      };
+    case "COMPLETED":
+      return {
+        label: "Completed",
+        icon: <IconCircleCheck className="h-3 w-3" />,
+        variant: "default" as const,
+        className: "bg-emerald-500/10 text-emerald-500 border-emerald-500/20",
+      };
+    case "FAILED":
+    case "CANCELLED":
+      return {
+        label: state === "FAILED" ? "Failed" : "Cancelled",
+        icon: <IconCircleX className="h-3 w-3" />,
+        variant: "destructive" as const,
+      };
+    case "BLOCKED":
+    case "WAITING_FOR_INPUT":
+      return {
+        label: state === "BLOCKED" ? "Blocked" : "Waiting for Input",
+        icon: <IconAlertTriangle className="h-3 w-3" />,
+        variant: "default" as const,
+        className: "bg-yellow-500/10 text-yellow-500 border-yellow-500/20",
+      };
+    case "TODO":
+      return {
+        label: "To Do",
+        icon: null,
+        variant: "secondary" as const,
+      };
+    case "REVIEW":
+      return {
+        label: "Review",
+        icon: null,
+        variant: "default" as const,
+      };
+    case "CREATED":
+    default:
+      return {
+        label: "Created",
+        icon: null,
+        variant: "secondary" as const,
+      };
+  }
+}
+
+export function TaskPreviewPanel({ task, onClose, onMaximize }: TaskPreviewPanelProps) {
+  if (!task) {
+    return (
+      <div className="flex h-full w-full flex-col border-l bg-background">
+        <div className="flex items-center justify-between border-b px-4 py-3">
+          <h2 className="text-sm font-semibold">Task Preview</h2>
+          <Button variant="ghost" size="icon" className="h-8 w-8 cursor-pointer" onClick={onClose}>
+            <IconX className="h-4 w-4" />
+            <span className="sr-only">Close preview</span>
+          </Button>
+        </div>
+        <div className="flex flex-1 items-center justify-center p-8">
+          <p className="text-sm text-muted-foreground">Select a task to preview</p>
+        </div>
+      </div>
+    );
+  }
+
+  const repoName = getRepositoryDisplayName(task.repositoryUrl);
+  const stateDisplay = getStateDisplay(task.state);
+
+  return (
+    <div className="flex h-full w-full flex-col border-l bg-background">
+      {/* Header */}
+      <div className="flex items-center justify-between border-b px-4 py-3">
+        <h2 className="text-sm font-semibold">Task Preview</h2>
+        <div className="flex items-center gap-1">
+          {onMaximize && (
+            <Button
+              variant="ghost"
+              size="icon"
+              className="h-8 w-8 cursor-pointer"
+              onClick={() => onMaximize(task)}
+              title="Open full page"
+            >
+              <IconArrowsMaximize className="h-4 w-4" />
+              <span className="sr-only">Open full page</span>
+            </Button>
+          )}
+          <Button variant="ghost" size="icon" className="h-8 w-8 cursor-pointer" onClick={onClose}>
+            <IconX className="h-4 w-4" />
+            <span className="sr-only">Close preview</span>
+          </Button>
+        </div>
+      </div>
+
+      {/* Content */}
+      <div className="flex-1 overflow-y-auto p-4">
+        <div className="space-y-4">
+          {/* Repository */}
+          {repoName && (
+            <div>
+              <p className="text-xs font-medium text-muted-foreground mb-1">Repository</p>
+              <p className="text-sm">{repoName}</p>
+            </div>
+          )}
+
+          {/* Title */}
+          <div>
+            <p className="text-xs font-medium text-muted-foreground mb-1">Title</p>
+            <h3 className="text-base font-semibold">{task.title}</h3>
+          </div>
+
+          {/* State */}
+          {task.state && (
+            <div>
+              <p className="text-xs font-medium text-muted-foreground mb-1">Status</p>
+              <Badge variant={stateDisplay.variant} className={stateDisplay.className}>
+                {stateDisplay.icon && <span className="mr-1">{stateDisplay.icon}</span>}
+                {stateDisplay.label}
+              </Badge>
+            </div>
+          )}
+
+          {/* Description */}
+          {task.description && (
+            <div>
+              <p className="text-xs font-medium text-muted-foreground mb-1">Description</p>
+              <p className="text-sm text-muted-foreground whitespace-pre-wrap">
+                {task.description}
+              </p>
+            </div>
+          )}
+        </div>
+      </div>
+    </div>
+  );
+}
diff --git a/apps/web/hooks/use-kanban-preview.ts b/apps/web/hooks/use-kanban-preview.ts
new file mode 100644
index 0000000000..94a8d6d533
--- /dev/null
+++ b/apps/web/hooks/use-kanban-preview.ts
@@ -0,0 +1,84 @@
+"use client";
+
+import { useState, useEffect, useCallback, useRef } from "react";
+import { getKanbanPreviewState, setKanbanPreviewState } from "@/lib/local-storage";
+import { PREVIEW_PANEL } from "@/lib/settings/constants";
+
+interface UseKanbanPreviewOptions {
+  onClose?: () => void;
+}
+
+export function useKanbanPreview(options: UseKanbanPreviewOptions = {}) {
+  // Always start with default values to avoid hydration mismatch
+  const [selectedTaskId, setSelectedTaskId] = useState<string | null>(null);
+  const [isOpen, setIsOpen] = useState(false);
+  const [previewWidthPx, setPreviewWidthPx] = useState(PREVIEW_PANEL.DEFAULT_WIDTH_PX);
+  const containerRef = useRef<HTMLDivElement | null>(null);
+
+  // Load persisted state from localStorage AFTER hydration
+  // This is necessary to avoid hydration mismatch between server and client
+  useEffect(() => {
+    const savedState = getKanbanPreviewState({
+      isOpen: false,
+      previewWidthPx: PREVIEW_PANEL.DEFAULT_WIDTH_PX,
+      selectedTaskId: null,
+    });
+
+    if (savedState.isOpen) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect
+      setIsOpen(true);
+    }
+    if (savedState.previewWidthPx) {
+      setPreviewWidthPx(Math.max(PREVIEW_PANEL.MIN_WIDTH_PX, savedState.previewWidthPx));
+    }
+    if (savedState.selectedTaskId) {
+      setSelectedTaskId(savedState.selectedTaskId);
+    }
+  }, []);
+
+  // Persist state to localStorage
+  useEffect(() => {
+    setKanbanPreviewState({ isOpen });
+  }, [isOpen]);
+
+  useEffect(() => {
+    if (isOpen && previewWidthPx > 0) {
+      setKanbanPreviewState({ previewWidthPx });
+    }
+  }, [isOpen, previewWidthPx]);
+
+  useEffect(() => {
+    setKanbanPreviewState({ selectedTaskId });
+  }, [selectedTaskId]);
+
+  const open = useCallback((taskId: string) => {
+    setSelectedTaskId(taskId);
+    setIsOpen(true);
+  }, []);
+
+  const close = useCallback(() => {
+    setIsOpen(false);
+    setSelectedTaskId(null);
+    options.onClose?.();
+  }, [options]);
+
+  const toggle = useCallback(() => {
+    setIsOpen((prev) => !prev);
+  }, []);
+
+  const updatePreviewWidth = useCallback((width: number) => {
+    setPreviewWidthPx(Math.max(PREVIEW_PANEL.MIN_WIDTH_PX, width));
+  }, []);
+
+  return {
+    selectedTaskId,
+    isOpen,
+    previewWidthPx,
+    open,
+    close,
+    toggle,
+    setSelectedTaskId,
+    updatePreviewWidth,
+    containerRef,
+  };
+}
diff --git a/apps/web/lib/local-storage.ts b/apps/web/lib/local-storage.ts
index 36e910007e..bf0608ab62 100644
--- a/apps/web/lib/local-storage.ts
+++ b/apps/web/lib/local-storage.ts
@@ -28,3 +28,50 @@ export function removeLocalStorage(key: string): void {
     // Ignore removal failures.
   }
 }
+
+// Internal storage keys for kanban preview (not exported - encapsulated)
+const KANBAN_PREVIEW_KEYS = {
+  OPEN: 'kandev.kanban.preview.open',
+  WIDTH: 'kandev.kanban.preview.width',
+  SELECTED_TASK: 'kandev.kanban.preview.selectedTask',
+} as const;
+
+// Kanban preview state type
+export interface KanbanPreviewState {
+  isOpen: boolean;
+  previewWidthPx: number;
+  selectedTaskId: string | null;
+}
+
+/**
+ * Get the kanban preview state from localStorage
+ * @param defaults - Default values to use if not found in localStorage
+ * @returns The kanban preview state
+ */
+export function getKanbanPreviewState(defaults: KanbanPreviewState): KanbanPreviewState {
+  return {
+    isOpen: getLocalStorage(KANBAN_PREVIEW_KEYS.OPEN, defaults.isOpen),
+    previewWidthPx: getLocalStorage(KANBAN_PREVIEW_KEYS.WIDTH, defaults.previewWidthPx),
+    selectedTaskId: getLocalStorage(KANBAN_PREVIEW_KEYS.SELECTED_TASK, defaults.selectedTaskId),
+  };
+}
+
+/**
+ * Set the kanban preview state in localStorage
+ * @param state - Partial state to update (only provided fields are updated)
+ */
+export function setKanbanPreviewState(state: Partial<KanbanPreviewState>): void {
+  if (state.isOpen !== undefined) {
+    setLocalStorage(KANBAN_PREVIEW_KEYS.OPEN, state.isOpen);
+  }
+  if (state.previewWidthPx !== undefined) {
+    setLocalStorage(KANBAN_PREVIEW_KEYS.WIDTH, state.previewWidthPx);
+  }
+  if (state.selectedTaskId !== undefined) {
+    if (state.selectedTaskId === null) {
+      removeLocalStorage(KANBAN_PREVIEW_KEYS.SELECTED_TASK);
+    } else {
+      setLocalStorage(KANBAN_PREVIEW_KEYS.SELECTED_TASK, state.selectedTaskId);
+    }
+  }
+}
diff --git a/apps/web/lib/settings/constants.ts b/apps/web/lib/settings/constants.ts
index 1667f70e20..32a9b442eb 100644
--- a/apps/web/lib/settings/constants.ts
+++ b/apps/web/lib/settings/constants.ts
@@ -4,3 +4,18 @@ export const STORAGE_KEYS = {
 } as const;
 
 export const DEFAULT_BACKEND_URL = 'http://localhost:8080';
+
+// Kanban Preview Panel Settings
+export const PREVIEW_PANEL = {
+  // Minimum width of the preview panel in pixels (prevents panel from being too narrow)
+  MIN_WIDTH_PX: 300,
+
+  // Default width of the preview panel in pixels when first opened
+  DEFAULT_WIDTH_PX: 500,
+
+  // Maximum width of the preview panel in viewport width percentage (prevents covering entire screen)
+  MAX_WIDTH_VW: 95,
+
+  // Minimum width of the kanban board as a percentage of viewport before the panel switches to floating mode
+  MIN_KANBAN_WIDTH_PERCENT: 50,
+} as const;