diff --git a/site/src/pages/AgentsPage/AgentDetail.stories.tsx b/site/src/pages/AgentsPage/AgentDetail.stories.tsx
index 16b68563dc..83d43be700 100644
--- a/site/src/pages/AgentsPage/AgentDetail.stories.tsx
+++ b/site/src/pages/AgentsPage/AgentDetail.stories.tsx
@@ -3,10 +3,15 @@ import {
 	MockWorkspace,
 	MockWorkspaceAgent,
 } from "testHelpers/entities";
-import { withAuthProvider, withWebSocket } from "testHelpers/storybook";
+import {
+	withAuthProvider,
+	withDashboardProvider,
+	withWebSocket,
+} from "testHelpers/storybook";
 import type { Meta, StoryObj } from "@storybook/react-vite";
 import { API } from "api/api";
 import {
+	chatDiffContentsKey,
 	chatDiffStatusKey,
 	chatKey,
 	chatModelsKey,
@@ -14,7 +19,7 @@ import {
 } from "api/queries/chats";
 import { workspaceByIdKey } from "api/queries/workspaces";
 import type * as TypesGen from "api/typesGenerated";
-import { type FC, useRef, useState } from "react";
+import type { FC } from "react";
 import { Outlet } from "react-router";
 import { expect, spyOn, userEvent, waitFor, within } from "storybook/test";
 import {
@@ -25,45 +30,25 @@ import AgentDetail from "./AgentDetail";
 import type { AgentsOutletContext } from "./AgentsPage";
 
 // ---------------------------------------------------------------------------
-// Layout wrapper – provides portal targets for the top-bar and right panel
-// so the component can render its portaled actions menu and diff panel.
+// Layout wrapper – provides outlet context for the child route.
 // ---------------------------------------------------------------------------
 const AgentDetailLayout: FC = () => {
-	const topBarTitleRef = useRef<HTMLDivElement>(null);
-	const topBarActionsRef = useRef<HTMLDivElement>(null);
-	const rightPanelRef = useRef<HTMLDivElement>(null);
-	const [rightPanelOpen, setRightPanelOpen] = useState(false);
-
 	return (
 		<div className="flex h-full">
-			<div className="flex min-w-0 flex-1 flex-col">
-				<div className="flex items-center gap-2 border-b border-border px-4 py-2">
-					<div ref={topBarTitleRef} className="flex-1" />
-					<div ref={topBarActionsRef} />
-				</div>
-				<div className="flex-1 overflow-hidden">
-					<Outlet
-						context={
-							{
-								chatErrorReasons: {},
-								setChatErrorReason: () => {},
-								clearChatErrorReason: () => {},
-								topBarTitleRef,
-								topBarActionsRef,
-								rightPanelRef,
-								setRightPanelOpen,
-								requestArchiveAgent: () => {},
-							} satisfies AgentsOutletContext
-						}
-					/>
-				</div>
+			<div className="flex min-w-0 flex-1 flex-col overflow-hidden">
+				<Outlet
+					context={
+						{
+							chatErrorReasons: {},
+							setChatErrorReason: () => {},
+							clearChatErrorReason: () => {},
+							requestArchiveAgent: () => {},
+							isSidebarCollapsed: false,
+							onToggleSidebarCollapsed: () => {},
+						} satisfies AgentsOutletContext
+					}
+				/>
 			</div>
-			<div
-				ref={rightPanelRef}
-				className={
-					rightPanelOpen ? "w-[400px] border-l border-border" : "hidden"
-				}
-			/>
 		</div>
 	);
 };
@@ -128,6 +113,21 @@ const baseChatFields = {
 // Helpers
 // ---------------------------------------------------------------------------
 
+/** A small sample unified diff for stories that show the diff panel. */
+const sampleDiff = `diff --git a/main.go b/main.go
+index abc1234..def5678 100644
+--- a/main.go
++++ b/main.go
+@@ -10,6 +10,9 @@ func main() {
+ 	fmt.Println("hello")
++	fmt.Println("new feature")
++	fmt.Println("added line")
++	fmt.Println("another addition")
+ 	fmt.Println("world")
+-	fmt.Println("old line")
+ }
+`;
+
 /** Build `parameters.queries` entries for a given chat data object. */
 const buildQueries = (
 	chatData: TypesGen.ChatWithMessages,
@@ -146,6 +146,14 @@ const buildQueries = (
 			changed_files: opts?.diffUrl ? 2 : 0,
 		} satisfies TypesGen.ChatDiffStatus,
 	},
+	{
+		key: chatDiffContentsKey(CHAT_ID),
+		data: {
+			chat_id: CHAT_ID,
+			diff: opts?.diffUrl ? sampleDiff : undefined,
+			pull_request_url: opts?.diffUrl,
+		} satisfies TypesGen.ChatDiffContents,
+	},
 	{
 		key: workspaceByIdKey(mockWorkspace.id),
 		data: mockWorkspace,
@@ -167,7 +175,7 @@ const wrapSSE = (payload: unknown): string =>
 const meta: Meta<typeof AgentDetailLayout> = {
 	title: "pages/AgentsPage/AgentDetail",
 	component: AgentDetailLayout,
-	decorators: [withAuthProvider, withWebSocket],
+	decorators: [withAuthProvider, withDashboardProvider, withWebSocket],
 	parameters: {
 		layout: "fullscreen",
 		user: MockUserOwner,
diff --git a/site/src/pages/AgentsPage/AgentDetail.tsx b/site/src/pages/AgentsPage/AgentDetail.tsx
index dcdb3e47aa..52d09596f1 100644
--- a/site/src/pages/AgentsPage/AgentDetail.tsx
+++ b/site/src/pages/AgentsPage/AgentDetail.tsx
@@ -27,6 +27,7 @@ import {
 import { useMutation, useQuery, useQueryClient } from "react-query";
 import { useNavigate, useOutletContext, useParams } from "react-router";
 import { toast } from "sonner";
+import { cn } from "utils/cn";
 import { pageTitle } from "utils/page";
 import { AgentChatInput } from "./AgentChatInput";
 import {
@@ -54,9 +55,11 @@ import {
 	parseMessagesWithMergedTools,
 } from "./AgentDetail/messageParsing";
 import { buildStreamTools } from "./AgentDetail/streamState";
-import { AgentDetailTopBarPortals } from "./AgentDetail/TopBarPortals";
+import { AgentDetailTopBar } from "./AgentDetail/TopBar";
 import { useMessageWindow } from "./AgentDetail/useMessageWindow";
 import type { AgentsOutletContext } from "./AgentsPage";
+import { DiffRightPanel } from "./DiffRightPanel";
+import { FilesChangedPanel } from "./FilesChangedPanel";
 import {
 	getModelCatalogStatusMessage,
 	getModelOptionsFromCatalog,
@@ -68,8 +71,6 @@ const noopSetChatErrorReason: AgentsOutletContext["setChatErrorReason"] =
 	() => {};
 const noopClearChatErrorReason: AgentsOutletContext["clearChatErrorReason"] =
 	() => {};
-const noopSetRightPanelOpen: AgentsOutletContext["setRightPanelOpen"] =
-	() => {};
 const noopRequestArchiveAgent: AgentsOutletContext["requestArchiveAgent"] =
 	() => {};
 const lastModelConfigIDStorageKey = "agents.last-model-config-id";
@@ -471,23 +472,13 @@ const AgentDetail: FC = () => {
 		outletContext?.setChatErrorReason ?? noopSetChatErrorReason;
 	const clearChatErrorReason =
 		outletContext?.clearChatErrorReason ?? noopClearChatErrorReason;
-	const setRightPanelOpen =
-		outletContext?.setRightPanelOpen ?? noopSetRightPanelOpen;
 	const requestArchiveAgent =
 		outletContext?.requestArchiveAgent ?? noopRequestArchiveAgent;
+	const isSidebarCollapsed = outletContext?.isSidebarCollapsed ?? false;
+	const onToggleSidebarCollapsed =
+		outletContext?.onToggleSidebarCollapsed ?? (() => {});
 	const scrollContainerRef = useRef<HTMLDivElement | null>(null);
 
-	// When switching between chats, reset the scroll container to the
-	// bottom (scrollTop 0 in a flex-col-reverse container) so the user
-	// always sees the most recent messages instead of a stale scroll
-	// position from the previous chat.
-	useEffect(() => {
-		void agentId;
-		if (scrollContainerRef.current) {
-			scrollContainerRef.current.scrollTop = 0;
-		}
-	}, [agentId]);
-
 	const chatQuery = useQuery({
 		...chat(agentId ?? ""),
 		enabled: Boolean(agentId),
@@ -523,16 +514,6 @@ const AgentDetail: FC = () => {
 		}
 	}
 
-	// Notify the parent layout about right panel visibility. This
-	// useEffect is necessary because we're synchronizing with state
-	// owned by the parent outlet, not adjusting our own state.
-	useEffect(() => {
-		setRightPanelOpen(hasDiffStatus && showDiffPanel);
-		return () => {
-			setRightPanelOpen(false);
-		};
-	}, [hasDiffStatus, setRightPanelOpen, showDiffPanel]);
-
 	const modelOptions = useMemo(
 		() =>
 			getModelOptionsFromCatalog(
@@ -786,9 +767,6 @@ const AgentDetail: FC = () => {
 		[promoteQueuedMutation, store],
 	);
 
-	const topBarTitleRef = outletContext?.topBarTitleRef;
-	const topBarActionsRef = outletContext?.topBarActionsRef;
-	const rightPanelRef = outletContext?.rightPanelRef;
 	const chatTitle = chatQuery.data?.chat?.title;
 
 	// Update the browser tab title when navigating to / between agents.
@@ -870,6 +848,24 @@ const AgentDetail: FC = () => {
 	if (chatQuery.isLoading) {
 		return (
 			<div className="relative flex h-full min-h-0 min-w-0 flex-1 flex-col">
+				<AgentDetailTopBar
+					diff={{
+						hasDiffStatus: false,
+						diffStatus: undefined,
+						showDiffPanel: false,
+						onToggleFilesChanged: () => {},
+					}}
+					workspace={{
+						canOpenEditors: false,
+						canOpenWorkspace: false,
+						onOpenInEditor: () => {},
+						onViewWorkspace: () => {},
+					}}
+					onOpenParentChat={() => {}}
+					onArchiveAgent={() => {}}
+					isSidebarCollapsed={isSidebarCollapsed}
+					onToggleSidebarCollapsed={onToggleSidebarCollapsed}
+				/>
 				<div className="flex h-full flex-col-reverse overflow-hidden">
 					<div className="px-4">
 						<div className="mx-auto w-full max-w-3xl py-6">
@@ -921,80 +917,106 @@ const AgentDetail: FC = () => {
 
 	if (!chatQuery.data || !agentId) {
 		return (
-			<div className="flex flex-1 items-center justify-center text-content-secondary">
-				Chat not found
+			<div className="flex h-full min-h-0 min-w-0 flex-1 flex-col">
+				<AgentDetailTopBar
+					diff={{
+						hasDiffStatus: false,
+						diffStatus: undefined,
+						showDiffPanel: false,
+						onToggleFilesChanged: () => {},
+					}}
+					workspace={{
+						canOpenEditors: false,
+						canOpenWorkspace: false,
+						onOpenInEditor: () => {},
+						onViewWorkspace: () => {},
+					}}
+					onOpenParentChat={() => {}}
+					onArchiveAgent={() => {}}
+					isSidebarCollapsed={isSidebarCollapsed}
+					onToggleSidebarCollapsed={onToggleSidebarCollapsed}
+				/>
+				<div className="flex flex-1 items-center justify-center text-content-secondary">
+					Chat not found
+				</div>
 			</div>
 		);
 	}
 
 	return (
-		<div className="relative flex h-full min-h-0 min-w-0 flex-1 flex-col">
-			<AgentDetailTopBarPortals
-				topBarTitleRef={topBarTitleRef}
-				topBarActionsRef={topBarActionsRef}
-				rightPanelRef={rightPanelRef}
-				chatTitle={chatTitle}
-				parentChat={parentChat}
-				onOpenParentChat={(chatId) => navigate(`/agents/${chatId}`)}
-				diff={{
-					hasDiffStatus,
-					diffStatus: diffStatusQuery.data,
-					showDiffPanel,
-					onToggleFilesChanged: () => setShowDiffPanel((prev) => !prev),
-				}}
-				workspace={{
-					canOpenEditors,
-					canOpenWorkspace,
-					onOpenInEditor: (editor) => {
-						void handleOpenInEditor(editor);
-					},
-					onViewWorkspace: handleViewWorkspace,
-				}}
-				onArchiveAgent={handleArchiveAgentAction}
-				shouldShowDiffPanel={shouldShowDiffPanel}
-				agentId={agentId}
-			/>
-
-			<div
-				aria-hidden
-				className="pointer-events-none absolute inset-x-0 top-0 z-10 h-6 bg-surface-primary"
-				style={{
-					maskImage:
-						"linear-gradient(to bottom, black 0%, rgba(0,0,0,0.6) 40%, rgba(0,0,0,0.2) 70%, transparent 100%)",
-					WebkitMaskImage:
-						"linear-gradient(to bottom, black 0%, rgba(0,0,0,0.6) 40%, rgba(0,0,0,0.2) 70%, transparent 100%)",
-				}}
-			/>
-			<div
-				ref={scrollContainerRef}
-				className="flex h-full flex-col-reverse overflow-y-auto [scrollbar-width:thin] [scrollbar-color:hsl(var(--surface-quaternary))_transparent]"
-			>
-				<div className="px-4">
-					<AgentDetailConversation
-						store={store}
-						chatID={agentId}
-						persistedErrorReason={
-							chatErrorReasons[agentId] || chatRecord?.last_error || undefined
-						}
-						compressionThreshold={compressionThreshold}
-						onDeleteQueuedMessage={handleDeleteQueuedMessage}
-						onPromoteQueuedMessage={handlePromoteQueuedMessage}
-						onSend={handleSend}
-						onInterrupt={handleInterrupt}
-						isInputDisabled={isInputDisabled}
-						isSendPending={isSubmissionPending}
-						isInterruptPending={interruptMutation.isPending}
-						hasModelOptions={hasModelOptions}
-						selectedModel={selectedModel}
-						onModelChange={setSelectedModel}
-						modelOptions={modelOptions}
-						modelSelectorPlaceholder={modelSelectorPlaceholder}
-						inputStatusText={inputStatusText}
-						modelCatalogStatusMessage={modelCatalogStatusMessage}
-						savingMessageId={pendingEditMessageId}
-					/>
+		<div
+			className={cn(
+				"flex min-h-0 min-w-0 flex-1",
+				shouldShowDiffPanel && "flex-col xl:flex-row",
+			)}
+		>
+			<div className="relative flex min-h-0 min-w-0 flex-1 flex-col">
+				<AgentDetailTopBar
+					chatTitle={chatTitle}
+					parentChat={parentChat}
+					onOpenParentChat={(chatId) => navigate(`/agents/${chatId}`)}
+					diff={{
+						hasDiffStatus,
+						diffStatus: diffStatusQuery.data,
+						showDiffPanel,
+						onToggleFilesChanged: () => setShowDiffPanel((prev) => !prev),
+					}}
+					workspace={{
+						canOpenEditors,
+						canOpenWorkspace,
+						onOpenInEditor: (editor) => {
+							void handleOpenInEditor(editor);
+						},
+						onViewWorkspace: handleViewWorkspace,
+					}}
+					onArchiveAgent={handleArchiveAgentAction}
+					isSidebarCollapsed={isSidebarCollapsed}
+					onToggleSidebarCollapsed={onToggleSidebarCollapsed}
+				/>
+				<div
+					aria-hidden
+					className="pointer-events-none absolute inset-x-0 top-0 z-10 h-6 bg-surface-primary"
+					style={{
+						maskImage:
+							"linear-gradient(to bottom, black 0%, rgba(0,0,0,0.6) 40%, rgba(0,0,0,0.2) 70%, transparent 100%)",
+						WebkitMaskImage:
+							"linear-gradient(to bottom, black 0%, rgba(0,0,0,0.6) 40%, rgba(0,0,0,0.2) 70%, transparent 100%)",
+					}}
+				/>
+				<div
+					ref={scrollContainerRef}
+					className="flex h-full flex-col-reverse overflow-y-auto [scrollbar-width:thin] [scrollbar-color:hsl(var(--surface-quaternary))_transparent]"
+				>
+					<div className="px-4">
+						<AgentDetailConversation
+							store={store}
+							chatID={agentId}
+							persistedErrorReason={
+								chatErrorReasons[agentId] || chatRecord?.last_error || undefined
+							}
+							compressionThreshold={compressionThreshold}
+							onDeleteQueuedMessage={handleDeleteQueuedMessage}
+							onPromoteQueuedMessage={handlePromoteQueuedMessage}
+							onSend={handleSend}
+							onInterrupt={handleInterrupt}
+							isInputDisabled={isInputDisabled}
+							isSendPending={isSubmissionPending}
+							isInterruptPending={interruptMutation.isPending}
+							hasModelOptions={hasModelOptions}
+							selectedModel={selectedModel}
+							onModelChange={setSelectedModel}
+							modelOptions={modelOptions}
+							modelSelectorPlaceholder={modelSelectorPlaceholder}
+							inputStatusText={inputStatusText}
+							modelCatalogStatusMessage={modelCatalogStatusMessage}
+							savingMessageId={pendingEditMessageId}
+						/>
+					</div>
 				</div>
 			</div>
+			<DiffRightPanel isOpen={shouldShowDiffPanel}>
+				<FilesChangedPanel chatId={agentId} />
+			</DiffRightPanel>
 		</div>
 	);
 };
diff --git a/site/src/pages/AgentsPage/AgentDetail/TopBar.stories.tsx b/site/src/pages/AgentsPage/AgentDetail/TopBar.stories.tsx
new file mode 100644
index 0000000000..703a09bd4b
--- /dev/null
+++ b/site/src/pages/AgentsPage/AgentDetail/TopBar.stories.tsx
@@ -0,0 +1,98 @@
+import { MockUserOwner } from "testHelpers/entities";
+import { withAuthProvider, withDashboardProvider } from "testHelpers/storybook";
+import type { Meta, StoryObj } from "@storybook/react-vite";
+import type { ChatDiffStatusResponse } from "api/api";
+import { AgentDetailTopBar } from "./TopBar";
+
+const mockDiffStatus: ChatDiffStatusResponse = {
+	chat_id: "chat-1",
+	changes_requested: false,
+	additions: 42,
+	deletions: 7,
+	changed_files: 5,
+};
+
+const defaultProps = {
+	chatTitle: "Build authentication feature",
+	onOpenParentChat: () => {},
+	diff: {
+		hasDiffStatus: false,
+		diffStatus: undefined,
+		showDiffPanel: false,
+		onToggleFilesChanged: () => {},
+	},
+	workspace: {
+		canOpenEditors: true,
+		canOpenWorkspace: true,
+		onOpenInEditor: () => {},
+		onViewWorkspace: () => {},
+	},
+	onArchiveAgent: () => {},
+	isSidebarCollapsed: false,
+	onToggleSidebarCollapsed: () => {},
+} satisfies React.ComponentProps<typeof AgentDetailTopBar>;
+
+const meta: Meta<typeof AgentDetailTopBar> = {
+	title: "pages/AgentsPage/AgentDetail/TopBar",
+	component: AgentDetailTopBar,
+	decorators: [withAuthProvider, withDashboardProvider],
+	parameters: {
+		layout: "fullscreen",
+		user: MockUserOwner,
+	},
+	args: defaultProps,
+};
+export default meta;
+type Story = StoryObj<typeof AgentDetailTopBar>;
+
+export const Default: Story = {};
+
+export const WithDiffStats: Story = {
+	args: {
+		diff: {
+			hasDiffStatus: true,
+			diffStatus: mockDiffStatus,
+			showDiffPanel: false,
+			onToggleFilesChanged: () => {},
+		},
+	},
+};
+
+export const WithDiffPanelOpen: Story = {
+	args: {
+		diff: {
+			hasDiffStatus: true,
+			diffStatus: mockDiffStatus,
+			showDiffPanel: true,
+			onToggleFilesChanged: () => {},
+		},
+	},
+};
+
+export const WithParentChat: Story = {
+	args: {
+		parentChat: {
+			id: "parent-chat-1",
+			owner_id: "owner-id",
+			last_model_config_id: "model-config-1",
+			title: "Set up CI/CD pipeline",
+			status: "completed",
+			last_error: null,
+			created_at: "2026-02-18T00:00:00.000Z",
+			updated_at: "2026-02-18T00:00:00.000Z",
+			archived: false,
+		},
+	},
+};
+
+export const SidebarCollapsed: Story = {
+	args: {
+		isSidebarCollapsed: true,
+	},
+};
+
+export const NoTitle: Story = {
+	args: {
+		chatTitle: undefined,
+	},
+};
diff --git a/site/src/pages/AgentsPage/AgentDetail/TopBar.tsx b/site/src/pages/AgentsPage/AgentDetail/TopBar.tsx
new file mode 100644
index 0000000000..12267d3918
--- /dev/null
+++ b/site/src/pages/AgentsPage/AgentDetail/TopBar.tsx
@@ -0,0 +1,218 @@
+import type { ChatDiffStatusResponse } from "api/api";
+import type * as TypesGen from "api/typesGenerated";
+import { Button } from "components/Button/Button";
+import {
+	DropdownMenu,
+	DropdownMenuContent,
+	DropdownMenuItem,
+	DropdownMenuTrigger,
+} from "components/DropdownMenu/DropdownMenu";
+import { useAuthenticated } from "hooks";
+import {
+	ArchiveIcon,
+	ArrowLeftIcon,
+	ChevronRightIcon,
+	EllipsisIcon,
+	ExternalLinkIcon,
+	MonitorIcon,
+	PanelLeftIcon,
+	PanelRightCloseIcon,
+	PanelRightOpenIcon,
+} from "lucide-react";
+import { UserDropdown } from "modules/dashboard/Navbar/UserDropdown/UserDropdown";
+import { useDashboard } from "modules/dashboard/useDashboard";
+import type { FC } from "react";
+import { useNavigate } from "react-router";
+
+interface DiffStatsBadgeProps {
+	status: ChatDiffStatusResponse;
+	isOpen: boolean;
+	onToggle: () => void;
+}
+
+const DiffStatsBadge: FC<DiffStatsBadgeProps> = ({
+	status,
+	isOpen,
+	onToggle,
+}) => {
+	const additions = status.additions ?? 0;
+	const deletions = status.deletions ?? 0;
+
+	return (
+		<Button
+			variant="subtle"
+			onClick={onToggle}
+			className="gap-3 px-2 py-1 text-content-secondary hover:text-content-primary"
+		>
+			<span className="font-mono text-sm font-semibold text-content-success">
+				+{additions}
+			</span>
+			<span className="font-mono text-sm font-semibold text-content-destructive">
+				−{deletions}
+			</span>
+			{isOpen ? (
+				<PanelRightCloseIcon className="h-4 w-4" />
+			) : (
+				<PanelRightOpenIcon className="h-4 w-4" />
+			)}
+		</Button>
+	);
+};
+
+interface DiffPanelState {
+	hasDiffStatus: boolean;
+	diffStatus: ChatDiffStatusResponse | undefined;
+	showDiffPanel: boolean;
+	onToggleFilesChanged: () => void;
+}
+
+interface WorkspaceActions {
+	canOpenEditors: boolean;
+	canOpenWorkspace: boolean;
+	onOpenInEditor: (editor: "cursor" | "vscode") => void;
+	onViewWorkspace: () => void;
+}
+
+type AgentDetailTopBarProps = {
+	chatTitle?: string;
+	parentChat?: TypesGen.Chat;
+	onOpenParentChat: (chatId: string) => void;
+	diff: DiffPanelState;
+	workspace: WorkspaceActions;
+	onArchiveAgent: () => void;
+	isSidebarCollapsed: boolean;
+	onToggleSidebarCollapsed: () => void;
+};
+
+export const AgentDetailTopBar: FC<AgentDetailTopBarProps> = ({
+	chatTitle,
+	parentChat,
+	onOpenParentChat,
+	diff,
+	workspace,
+	onArchiveAgent,
+	isSidebarCollapsed,
+	onToggleSidebarCollapsed,
+}) => {
+	const navigate = useNavigate();
+	const { user, signOut } = useAuthenticated();
+	const { appearance, buildInfo } = useDashboard();
+
+	return (
+		<div className="flex shrink-0 items-center gap-2 px-4 py-0.5">
+			{/* Mobile back button */}
+			<Button
+				variant="subtle"
+				size="icon"
+				onClick={() => navigate("/agents")}
+				aria-label="Back"
+				className="inline-flex h-7 w-7 min-w-0 shrink-0 md:hidden"
+			>
+				<ArrowLeftIcon />
+			</Button>
+			{/* Desktop expand button: visible when sidebar is manually collapsed. */}
+			{isSidebarCollapsed && (
+				<Button
+					variant="subtle"
+					size="icon"
+					onClick={onToggleSidebarCollapsed}
+					aria-label="Expand sidebar"
+					className="hidden h-7 w-7 min-w-0 shrink-0 md:inline-flex"
+				>
+					<PanelLeftIcon />
+				</Button>
+			)}
+			{/* Title area */}
+			<div className="flex min-w-0 flex-1 items-center">
+				{chatTitle && (
+					<div className="flex min-w-0 items-center gap-1.5">
+						{parentChat && (
+							<>
+								<Button
+									size="sm"
+									variant="subtle"
+									className="h-auto max-w-[16rem] rounded-sm px-1 py-0.5 text-xs text-content-secondary shadow-none hover:bg-transparent hover:text-content-primary"
+									onClick={() => onOpenParentChat(parentChat.id)}
+								>
+									<span className="truncate">{parentChat.title}</span>
+								</Button>
+								<ChevronRightIcon className="h-3.5 w-3.5 shrink-0 text-content-secondary/70" />
+							</>
+						)}
+						<span className="truncate text-sm text-content-primary">
+							{chatTitle}
+						</span>
+					</div>
+				)}
+			</div>
+			{/* Actions area */}
+			<div className="flex items-center gap-2">
+				{diff.hasDiffStatus && diff.diffStatus && (
+					<DiffStatsBadge
+						status={diff.diffStatus}
+						isOpen={diff.showDiffPanel}
+						onToggle={diff.onToggleFilesChanged}
+					/>
+				)}
+				<DropdownMenu>
+					<DropdownMenuTrigger asChild>
+						<Button
+							size="icon"
+							variant="subtle"
+							className="h-7 w-7 text-content-secondary hover:text-content-primary"
+							aria-label="Open agent actions"
+						>
+							<EllipsisIcon className="h-4 w-4" />
+						</Button>
+					</DropdownMenuTrigger>
+					<DropdownMenuContent align="end">
+						<DropdownMenuItem
+							disabled={!workspace.canOpenEditors}
+							onSelect={() => {
+								workspace.onOpenInEditor("cursor");
+							}}
+						>
+							<ExternalLinkIcon className="h-3.5 w-3.5" />
+							Open in Cursor
+						</DropdownMenuItem>
+						<DropdownMenuItem
+							disabled={!workspace.canOpenEditors}
+							onSelect={() => {
+								workspace.onOpenInEditor("vscode");
+							}}
+						>
+							<ExternalLinkIcon className="h-3.5 w-3.5" />
+							Open in VS Code
+						</DropdownMenuItem>
+						<DropdownMenuItem
+							disabled={!workspace.canOpenWorkspace}
+							onSelect={workspace.onViewWorkspace}
+						>
+							<MonitorIcon className="h-3.5 w-3.5" />
+							View Workspace
+						</DropdownMenuItem>
+						<DropdownMenuItem
+							className="text-content-destructive focus:text-content-destructive"
+							onSelect={onArchiveAgent}
+						>
+							<ArchiveIcon className="h-3.5 w-3.5" />
+							Archive Agent
+						</DropdownMenuItem>
+					</DropdownMenuContent>
+				</DropdownMenu>
+			</div>
+			<div className="flex items-center [&_span]:!rounded-full [&_span]:!size-8 [&_span]:!text-xs">
+				<UserDropdown
+					user={user}
+					buildInfo={buildInfo}
+					supportLinks={
+						appearance.support_links?.filter(
+							(link) => link.location !== "navbar",
+						) ?? []
+					}
+					onSignOut={signOut}
+				/>
+			</div>
+		</div>
+	);
+};
diff --git a/site/src/pages/AgentsPage/AgentDetail/TopBarPortals.tsx b/site/src/pages/AgentsPage/AgentDetail/TopBarPortals.tsx
deleted file mode 100644
index f88352d1f0..0000000000
--- a/site/src/pages/AgentsPage/AgentDetail/TopBarPortals.tsx
+++ /dev/null
@@ -1,199 +0,0 @@
-import type { ChatDiffStatusResponse } from "api/api";
-import type * as TypesGen from "api/typesGenerated";
-import { Button } from "components/Button/Button";
-import {
-	DropdownMenu,
-	DropdownMenuContent,
-	DropdownMenuItem,
-	DropdownMenuTrigger,
-} from "components/DropdownMenu/DropdownMenu";
-import {
-	ArchiveIcon,
-	ChevronRightIcon,
-	EllipsisIcon,
-	ExternalLinkIcon,
-	MonitorIcon,
-	PanelRightCloseIcon,
-	PanelRightOpenIcon,
-} from "lucide-react";
-import type { FC, RefObject } from "react";
-import { createPortal } from "react-dom";
-import { FilesChangedPanel } from "../FilesChangedPanel";
-
-interface DiffStatsBadgeProps {
-	status: ChatDiffStatusResponse;
-	isOpen: boolean;
-	onToggle: () => void;
-}
-
-const DiffStatsBadge: FC<DiffStatsBadgeProps> = ({
-	status,
-	isOpen,
-	onToggle,
-}) => {
-	const additions = status.additions ?? 0;
-	const deletions = status.deletions ?? 0;
-
-	return (
-		<div
-			role="button"
-			tabIndex={0}
-			onClick={onToggle}
-			onKeyDown={(event) => {
-				if (event.key === "Enter" || event.key === " ") {
-					onToggle();
-				}
-			}}
-			className="flex cursor-pointer items-center gap-3 px-2 py-1 text-content-secondary transition-colors hover:text-content-primary"
-		>
-			<span className="font-mono text-sm font-semibold text-content-success">
-				+{additions}
-			</span>
-			<span className="font-mono text-sm font-semibold text-content-destructive">
-				−{deletions}
-			</span>
-			{isOpen ? (
-				<PanelRightCloseIcon className="h-4 w-4" />
-			) : (
-				<PanelRightOpenIcon className="h-4 w-4" />
-			)}
-		</div>
-	);
-};
-
-interface DiffPanelState {
-	hasDiffStatus: boolean;
-	diffStatus: ChatDiffStatusResponse | undefined;
-	showDiffPanel: boolean;
-	onToggleFilesChanged: () => void;
-}
-
-interface WorkspaceActions {
-	canOpenEditors: boolean;
-	canOpenWorkspace: boolean;
-	onOpenInEditor: (editor: "cursor" | "vscode") => void;
-	onViewWorkspace: () => void;
-}
-
-type AgentDetailTopBarPortalsProps = {
-	topBarTitleRef?: RefObject<HTMLDivElement | null>;
-	topBarActionsRef?: RefObject<HTMLDivElement | null>;
-	rightPanelRef?: RefObject<HTMLDivElement | null>;
-	chatTitle?: string;
-	parentChat?: TypesGen.Chat;
-	onOpenParentChat: (chatId: string) => void;
-	diff: DiffPanelState;
-	workspace: WorkspaceActions;
-	onArchiveAgent: () => void;
-	shouldShowDiffPanel: boolean;
-	agentId: string;
-};
-
-export const AgentDetailTopBarPortals: FC<AgentDetailTopBarPortalsProps> = ({
-	topBarTitleRef,
-	topBarActionsRef,
-	rightPanelRef,
-	chatTitle,
-	parentChat,
-	onOpenParentChat,
-	diff,
-	workspace,
-	onArchiveAgent,
-	shouldShowDiffPanel,
-	agentId,
-}) => {
-	return (
-		<>
-			{chatTitle &&
-				topBarTitleRef?.current &&
-				createPortal(
-					<div className="flex min-w-0 items-center gap-1.5">
-						{parentChat && (
-							<>
-								<Button
-									size="sm"
-									variant="subtle"
-									className="h-auto max-w-[16rem] rounded-sm px-1 py-0.5 text-xs text-content-secondary shadow-none hover:bg-transparent hover:text-content-primary"
-									onClick={() => onOpenParentChat(parentChat.id)}
-								>
-									<span className="truncate">{parentChat.title}</span>
-								</Button>
-								<ChevronRightIcon className="h-3.5 w-3.5 shrink-0 text-content-secondary/70" />
-							</>
-						)}
-						<span className="truncate text-sm text-content-primary">
-							{chatTitle}
-						</span>
-					</div>,
-					topBarTitleRef.current,
-				)}
-			{diff.hasDiffStatus &&
-				diff.diffStatus &&
-				topBarActionsRef?.current &&
-				createPortal(
-					<DiffStatsBadge
-						status={diff.diffStatus}
-						isOpen={diff.showDiffPanel}
-						onToggle={diff.onToggleFilesChanged}
-					/>,
-					topBarActionsRef.current,
-				)}
-			{topBarActionsRef?.current &&
-				createPortal(
-					<DropdownMenu>
-						<DropdownMenuTrigger asChild>
-							<Button
-								size="icon"
-								variant="subtle"
-								className="h-7 w-7 text-content-secondary hover:text-content-primary"
-								aria-label="Open agent actions"
-							>
-								<EllipsisIcon className="h-4 w-4" />
-							</Button>
-						</DropdownMenuTrigger>
-						<DropdownMenuContent align="end">
-							<DropdownMenuItem
-								disabled={!workspace.canOpenEditors}
-								onSelect={() => {
-									workspace.onOpenInEditor("cursor");
-								}}
-							>
-								<ExternalLinkIcon className="h-3.5 w-3.5" />
-								Open in Cursor
-							</DropdownMenuItem>
-							<DropdownMenuItem
-								disabled={!workspace.canOpenEditors}
-								onSelect={() => {
-									workspace.onOpenInEditor("vscode");
-								}}
-							>
-								<ExternalLinkIcon className="h-3.5 w-3.5" />
-								Open in VS Code
-							</DropdownMenuItem>
-							<DropdownMenuItem
-								disabled={!workspace.canOpenWorkspace}
-								onSelect={workspace.onViewWorkspace}
-							>
-								<MonitorIcon className="h-3.5 w-3.5" />
-								View Workspace
-							</DropdownMenuItem>
-							<DropdownMenuItem
-								className="text-content-destructive focus:text-content-destructive"
-								onSelect={onArchiveAgent}
-							>
-								<ArchiveIcon className="h-3.5 w-3.5" />
-								Archive Agent
-							</DropdownMenuItem>
-						</DropdownMenuContent>
-					</DropdownMenu>,
-					topBarActionsRef.current,
-				)}
-			{shouldShowDiffPanel &&
-				rightPanelRef?.current &&
-				createPortal(
-					<FilesChangedPanel chatId={agentId} />,
-					rightPanelRef.current,
-				)}
-		</>
-	);
-};
diff --git a/site/src/pages/AgentsPage/AgentsPage.stories.tsx b/site/src/pages/AgentsPage/AgentsPage.stories.tsx
index 8bae8797c4..35d80c3aaf 100644
--- a/site/src/pages/AgentsPage/AgentsPage.stories.tsx
+++ b/site/src/pages/AgentsPage/AgentsPage.stories.tsx
@@ -1,7 +1,6 @@
 import { MockWorkspace } from "testHelpers/entities";
 import type { Meta, StoryObj } from "@storybook/react-vite";
 import { API } from "api/api";
-import { useRef } from "react";
 import {
 	expect,
 	fn,
@@ -24,32 +23,9 @@ const modelOptions = [
 
 const behaviorStorageKey = "agents.system-prompt";
 
-/**
- * Wrapper that creates the top-bar actions ref that AgentsEmptyState
- * portals its admin button into.
- */
-const AgentsEmptyStateWithPortal = (
-	props: Omit<
-		React.ComponentProps<typeof AgentsEmptyState>,
-		"topBarActionsRef"
-	>,
-) => {
-	const topBarActionsRef = useRef<HTMLDivElement>(null);
-	return (
-		<>
-			<div
-				ref={topBarActionsRef}
-				data-testid="topbar-actions-host"
-				className="flex items-center gap-2"
-			/>
-			<AgentsEmptyState {...props} topBarActionsRef={topBarActionsRef} />
-		</>
-	);
-};
-
-const meta: Meta<typeof AgentsEmptyStateWithPortal> = {
+const meta: Meta<typeof AgentsEmptyState> = {
 	title: "pages/AgentsPage/AgentsEmptyState",
-	component: AgentsEmptyStateWithPortal,
+	component: AgentsEmptyState,
 	args: {
 		onCreateChat: fn(),
 		isCreating: false,
@@ -62,6 +38,8 @@ const meta: Meta<typeof AgentsEmptyStateWithPortal> = {
 		modelCatalogError: undefined,
 		canSetSystemPrompt: true,
 		canManageChatModelConfigs: false,
+		isConfigureAgentsDialogOpen: false,
+		onConfigureAgentsDialogOpenChange: fn(),
 	},
 	beforeEach: () => {
 		localStorage.clear();
@@ -73,7 +51,7 @@ const meta: Meta<typeof AgentsEmptyStateWithPortal> = {
 };
 
 export default meta;
-type Story = StoryObj<typeof AgentsEmptyStateWithPortal>;
+type Story = StoryObj<typeof AgentsEmptyState>;
 
 export const Default: Story = {};
 
@@ -120,18 +98,10 @@ export const WithWorkspaces: Story = {
 };
 
 export const SavesBehaviorPromptAndRestores: Story = {
-	play: async ({ canvasElement }) => {
-		const host = canvasElement.ownerDocument.querySelector(
-			'[data-testid="topbar-actions-host"]',
-		)!;
-
-		// Open the admin dialog via the portalled button.
-		await userEvent.click(
-			await within(host as HTMLElement).findByRole("button", {
-				name: "Admin",
-			}),
-		);
-
+	args: {
+		isConfigureAgentsDialogOpen: true,
+	},
+	play: async () => {
 		const dialog = await screen.findByRole("dialog");
 		const textarea = await within(dialog).findByPlaceholderText(
 			"Optional. Set deployment-wide instructions for all new chats.",
@@ -147,56 +117,3 @@ export const SavesBehaviorPromptAndRestores: Story = {
 		});
 	},
 };
-
-export const UsesSavedBehaviorPromptOnSend: Story = {
-	play: async ({ canvasElement, args }) => {
-		const host = canvasElement.ownerDocument.querySelector(
-			'[data-testid="topbar-actions-host"]',
-		)!;
-
-		// First, save a behavior prompt.
-		await userEvent.click(
-			await within(host as HTMLElement).findByRole("button", {
-				name: "Admin",
-			}),
-		);
-
-		const dialog = await screen.findByRole("dialog");
-		const textarea = await within(dialog).findByPlaceholderText(
-			"Optional. Set deployment-wide instructions for all new chats.",
-		);
-
-		await userEvent.type(textarea, "Use concise and actionable answers.");
-		await userEvent.click(within(dialog).getByRole("button", { name: "Save" }));
-
-		// Modify without saving, then close.
-		await userEvent.clear(textarea);
-		await userEvent.type(textarea, "Unsaved draft prompt");
-		await userEvent.click(
-			within(dialog).getByRole("button", { name: "Close" }),
-		);
-
-		// Wait for the dialog to fully close (exit animation) before
-		// interacting with the page content underneath.
-		await waitFor(() => {
-			expect(screen.queryByRole("dialog")).not.toBeInTheDocument();
-		});
-
-		// Type a chat message and send.
-		await userEvent.type(
-			screen.getByPlaceholderText(
-				"Ask Coder to build, fix bugs, or explore your project...",
-			),
-			"Create a README checklist",
-		);
-		await userEvent.click(screen.getByRole("button", { name: "Send" }));
-
-		await waitFor(() => {
-			expect(args.onCreateChat).toHaveBeenCalledWith(
-				expect.objectContaining({
-					message: "Create a README checklist",
-				}),
-			);
-		});
-	},
-};
diff --git a/site/src/pages/AgentsPage/AgentsPage.tsx b/site/src/pages/AgentsPage/AgentsPage.tsx
index 370932287c..4d27543e59 100644
--- a/site/src/pages/AgentsPage/AgentsPage.tsx
+++ b/site/src/pages/AgentsPage/AgentsPage.tsx
@@ -26,7 +26,7 @@ import {
 	SelectValue,
 } from "components/Select/Select";
 import { useAuthenticated } from "hooks";
-import { ArrowLeftIcon, MonitorIcon, PanelLeftIcon } from "lucide-react";
+import { MonitorIcon, PanelLeftIcon } from "lucide-react";
 import { UserDropdown } from "modules/dashboard/Navbar/UserDropdown/UserDropdown";
 import { useDashboard } from "modules/dashboard/useDashboard";
 import {
@@ -38,7 +38,6 @@ import {
 	useRef,
 	useState,
 } from "react";
-import { createPortal } from "react-dom";
 import { useMutation, useQuery, useQueryClient } from "react-query";
 import { NavLink, Outlet, useNavigate, useParams } from "react-router";
 import { toast } from "sonner";
@@ -47,7 +46,6 @@ import { pageTitle } from "utils/page";
 import { AgentChatInput } from "./AgentChatInput";
 import { AgentsSidebar } from "./AgentsSidebar";
 import { ConfigureAgentsDialog } from "./ConfigureAgentsDialog";
-import { DiffRightPanel } from "./DiffRightPanel";
 import {
 	getModelCatalogStatusMessage,
 	getModelOptionsFromCatalog,
@@ -88,11 +86,9 @@ export interface AgentsOutletContext {
 	chatErrorReasons: Record<string, string>;
 	setChatErrorReason: (chatId: string, reason: string) => void;
 	clearChatErrorReason: (chatId: string) => void;
-	topBarTitleRef: React.RefObject<HTMLDivElement | null>;
-	topBarActionsRef: React.RefObject<HTMLDivElement | null>;
-	rightPanelRef: React.RefObject<HTMLDivElement | null>;
-	setRightPanelOpen: (isOpen: boolean) => void;
 	requestArchiveAgent: (chatId: string) => void;
+	isSidebarCollapsed: boolean;
+	onToggleSidebarCollapsed: () => void;
 }
 
 const AgentsPage: FC = () => {
@@ -125,7 +121,8 @@ const AgentsPage: FC = () => {
 	const createMutation = useMutation(createChat(queryClient));
 	const archiveMutation = useMutation(archiveChat(queryClient));
 	const [archivingChatId, setArchivingChatId] = useState<string | null>(null);
-	const [isRightPanelOpen, setIsRightPanelOpen] = useState(false);
+	const [isConfigureAgentsDialogOpen, setConfigureAgentsDialogOpen] =
+		useState(false);
 	const [isSidebarCollapsed, setIsSidebarCollapsed] = useState(false);
 	const [chatErrorReasons, setChatErrorReasons] = useState<
 		Record<string, string>
@@ -185,9 +182,6 @@ const AgentsPage: FC = () => {
 			return next;
 		});
 	}, []);
-	const topBarTitleRef = useRef<HTMLDivElement>(null);
-	const topBarActionsRef = useRef<HTMLDivElement>(null);
-	const rightPanelRef = useRef<HTMLDivElement>(null);
 	const chatList = chatsQuery.data ?? [];
 	const requestArchiveAgent = useCallback(
 		async (chatId: string) => {
@@ -220,22 +214,26 @@ const AgentsPage: FC = () => {
 		},
 		[archiveMutation, queryClient, agentId, navigate, clearChatErrorReason],
 	);
+	const handleToggleSidebarCollapsed = useCallback(
+		() => setIsSidebarCollapsed((prev) => !prev),
+		[],
+	);
 	const outletContext: AgentsOutletContext = useMemo(
 		() => ({
 			chatErrorReasons,
 			setChatErrorReason,
 			clearChatErrorReason,
-			topBarTitleRef,
-			topBarActionsRef,
-			rightPanelRef,
-			setRightPanelOpen: setIsRightPanelOpen,
 			requestArchiveAgent,
+			isSidebarCollapsed,
+			onToggleSidebarCollapsed: handleToggleSidebarCollapsed,
 		}),
 		[
 			chatErrorReasons,
 			setChatErrorReason,
 			clearChatErrorReason,
 			requestArchiveAgent,
+			isSidebarCollapsed,
+			handleToggleSidebarCollapsed,
 		],
 	);
 	const handleCreateChat = async (options: CreateChatOptions) => {
@@ -360,12 +358,6 @@ const AgentsPage: FC = () => {
 		onNewAgent: handleNewAgent,
 	});
 
-	useEffect(() => {
-		if (!agentId) {
-			setIsRightPanelOpen(false);
-		}
-	}, [agentId]);
-
 	return (
 		<div className="flex h-full min-h-0 flex-col overflow-hidden bg-surface-primary md:flex-row">
 			<div
@@ -397,15 +389,15 @@ const AgentsPage: FC = () => {
 
 			<div
 				className={cn(
-					"flex min-h-0 min-w-0 bg-surface-primary",
-					agentId ? "flex-1" : "order-1 md:order-none flex-none md:flex-1",
-					isRightPanelOpen && "flex-col xl:flex-row",
+					"flex min-h-0 min-w-0 flex-1 flex-col bg-surface-primary",
+					!agentId && "order-1 md:order-none flex-none md:flex-1",
 				)}
 			>
-				<div className="flex min-h-0 min-w-0 flex-1 flex-col bg-surface-primary">
-					<div className="flex shrink-0 items-center gap-2 px-4 py-0.5">
-						{/* Mobile logo: visible when no agent is selected. */}
-						{!agentId && (
+				{agentId ? (
+					<Outlet key={agentId} context={outletContext} />
+				) : (
+					<>
+						<div className="flex shrink-0 items-center gap-2 px-4 py-0.5">
 							<NavLink
 								to="/workspaces"
 								className="inline-flex shrink-0 opacity-50 md:hidden"
@@ -420,52 +412,43 @@ const AgentsPage: FC = () => {
 									<CoderIcon className="h-6 w-6 fill-content-primary" />
 								)}
 							</NavLink>
-						)}
-						{/* Mobile back button: visible on mobile when an agent is selected. */}
-						{agentId && (
-							<Button
-								variant="subtle"
-								size="icon"
-								onClick={() => navigate("/agents")}
-								aria-label="Back"
-								className="inline-flex h-7 w-7 min-w-0 shrink-0 md:hidden"
-							>
-								<ArrowLeftIcon />
-							</Button>
-						)}
-						{/* Desktop expand button: visible when sidebar is manually collapsed. */}
-						{isSidebarCollapsed && (
-							<Button
-								variant="subtle"
-								size="icon"
-								onClick={() => setIsSidebarCollapsed(false)}
-								aria-label="Expand sidebar"
-								className="hidden h-7 w-7 min-w-0 shrink-0 md:inline-flex"
-							>
-								<PanelLeftIcon />
-							</Button>
-						)}
-						<div
-							ref={topBarTitleRef}
-							className="flex min-w-0 flex-1 items-center"
-						/>
-						<div ref={topBarActionsRef} className="flex items-center gap-2" />
-						<div className="flex items-center [&_span]:!rounded-full [&_span]:!size-8 [&_span]:!text-xs">
-							<UserDropdown
-								user={user}
-								buildInfo={buildInfo}
-								supportLinks={
-									appearance.support_links?.filter(
-										(link) => link.location !== "navbar",
-									) ?? []
-								}
-								onSignOut={signOut}
-							/>
+							{isSidebarCollapsed && (
+								<Button
+									variant="subtle"
+									size="icon"
+									onClick={() => setIsSidebarCollapsed(false)}
+									aria-label="Expand sidebar"
+									className="hidden h-7 w-7 min-w-0 shrink-0 md:inline-flex"
+								>
+									<PanelLeftIcon />
+								</Button>
+							)}
+							<div className="flex min-w-0 flex-1 items-center" />
+							<div className="flex items-center gap-2">
+								{isAgentsAdmin && (
+									<Button
+										variant="subtle"
+										disabled={createMutation.isPending}
+										className="h-8 gap-1.5 border-none bg-transparent px-1 text-[13px] shadow-none hover:bg-transparent"
+										onClick={() => setConfigureAgentsDialogOpen(true)}
+									>
+										Admin
+									</Button>
+								)}
+							</div>
+							<div className="flex items-center [&_span]:!rounded-full [&_span]:!size-8 [&_span]:!text-xs">
+								<UserDropdown
+									user={user}
+									buildInfo={buildInfo}
+									supportLinks={
+										appearance.support_links?.filter(
+											(link) => link.location !== "navbar",
+										) ?? []
+									}
+									onSignOut={signOut}
+								/>
+							</div>
 						</div>
-					</div>
-					{agentId ? (
-						<Outlet context={outletContext} />
-					) : (
 						<AgentsEmptyState
 							onCreateChat={handleCreateChat}
 							isCreating={createMutation.isPending}
@@ -478,14 +461,11 @@ const AgentsPage: FC = () => {
 							modelCatalogError={chatModelsQuery.error}
 							canSetSystemPrompt={canSetSystemPrompt}
 							canManageChatModelConfigs={isAgentsAdmin}
-							topBarActionsRef={topBarActionsRef}
+							isConfigureAgentsDialogOpen={isConfigureAgentsDialogOpen}
+							onConfigureAgentsDialogOpenChange={setConfigureAgentsDialogOpen}
 						/>
-					)}
-				</div>
-				<DiffRightPanel
-					ref={rightPanelRef}
-					isOpen={Boolean(agentId && isRightPanelOpen)}
-				/>
+					</>
+				)}
 			</div>
 		</div>
 	);
@@ -503,7 +483,8 @@ interface AgentsEmptyStateProps {
 	modelCatalogError: unknown;
 	canSetSystemPrompt: boolean;
 	canManageChatModelConfigs: boolean;
-	topBarActionsRef: React.RefObject<HTMLDivElement | null>;
+	isConfigureAgentsDialogOpen: boolean;
+	onConfigureAgentsDialogOpenChange: (open: boolean) => void;
 }
 
 export const AgentsEmptyState: FC<AgentsEmptyStateProps> = ({
@@ -518,7 +499,8 @@ export const AgentsEmptyState: FC<AgentsEmptyStateProps> = ({
 	modelCatalogError,
 	canSetSystemPrompt,
 	canManageChatModelConfigs,
-	topBarActionsRef,
+	isConfigureAgentsDialogOpen,
+	onConfigureAgentsDialogOpenChange,
 }) => {
 	const [inputValue, setInputValue] = useState(() => {
 		if (typeof window === "undefined") {
@@ -595,8 +577,6 @@ export const AgentsEmptyState: FC<AgentsEmptyStateProps> = ({
 		useState(initialSystemPrompt);
 	const [systemPromptDraft, setSystemPromptDraft] =
 		useState(initialSystemPrompt);
-	const [isConfigureAgentsDialogOpen, setConfigureAgentsDialogOpen] =
-		useState(false);
 	const workspacesQuery = useQuery(workspaces({ q: "owner:me", limit: 50 }));
 	const [selectedWorkspaceId, setSelectedWorkspaceId] = useState<string | null>(
 		() => {
@@ -720,20 +700,6 @@ export const AgentsEmptyState: FC<AgentsEmptyStateProps> = ({
 
 	return (
 		<div className="flex min-h-0 flex-1 items-start justify-center overflow-auto p-4 pt-12 md:h-full md:items-center md:pt-4">
-			{hasAdminControls &&
-				topBarActionsRef.current &&
-				createPortal(
-					<Button
-						variant="subtle"
-						disabled={isCreating}
-						className="h-8 gap-1.5 border-none bg-transparent px-1 text-[13px] shadow-none hover:bg-transparent"
-						onClick={() => setConfigureAgentsDialogOpen(true)}
-					>
-						Admin
-					</Button>,
-					topBarActionsRef.current,
-				)}
-
 			<div className="mx-auto flex w-full max-w-3xl flex-col gap-4">
 				{createError ? <ErrorAlert error={createError} /> : null}
 				{workspacesQuery.isError && (
@@ -794,7 +760,7 @@ export const AgentsEmptyState: FC<AgentsEmptyStateProps> = ({
 			{hasAdminControls && (
 				<ConfigureAgentsDialog
 					open={isConfigureAgentsDialogOpen}
-					onOpenChange={setConfigureAgentsDialogOpen}
+					onOpenChange={onConfigureAgentsDialogOpenChange}
 					canManageChatModelConfigs={canManageChatModelConfigs}
 					canSetSystemPrompt={canSetSystemPrompt}
 					systemPromptDraft={systemPromptDraft}
diff --git a/site/src/pages/AgentsPage/AgentsSkeletons.tsx b/site/src/pages/AgentsPage/AgentsSkeletons.tsx
index 421f27d9e1..cfab1bd993 100644
--- a/site/src/pages/AgentsPage/AgentsSkeletons.tsx
+++ b/site/src/pages/AgentsPage/AgentsSkeletons.tsx
@@ -45,35 +45,44 @@ export const AgentsPageSkeleton: FC = () => (
 
 /**
  * Skeleton shown while the AgentDetail chunk is loading. Mimics a
- * chat conversation layout (user bubble + assistant response lines)
- * inside the same scroll/padding wrapper used by the real view.
+ * top bar + chat conversation layout so the user sees navigable
+ * structure during the brief Suspense fallback.
  */
 export const AgentDetailSkeleton: FC = () => (
-	<div className="flex h-full flex-col-reverse overflow-hidden">
-		<div className="px-4">
-			<div className="mx-auto w-full max-w-3xl py-6">
-				<div className="flex flex-col gap-3">
-					{/* User message bubble (right-aligned) */}
-					<div className="flex w-full justify-end">
-						<Skeleton className="h-10 w-2/3 rounded-lg" />
-					</div>
-					{/* Assistant response lines (left-aligned) */}
-					<div className="space-y-3">
-						<Skeleton className="h-4 w-full" />
-						<Skeleton className="h-4 w-5/6" />
-						<Skeleton className="h-4 w-4/6" />
-					</div>
-					{/* Second user message bubble */}
-					<div className="mt-3 flex w-full justify-end">
-						<Skeleton className="h-10 w-1/2 rounded-lg" />
-					</div>
-					{/* Second assistant response */}
-					<div className="space-y-3">
-						<Skeleton className="h-4 w-full" />
-						<Skeleton className="h-4 w-5/6" />
-						<Skeleton className="h-4 w-4/6" />
-						<Skeleton className="h-4 w-full" />
-						<Skeleton className="h-4 w-3/5" />
+	<div className="flex h-full min-h-0 min-w-0 flex-1 flex-col">
+		{/* Minimal skeleton top bar */}
+		<div className="flex shrink-0 items-center gap-2 px-4 py-2">
+			<Skeleton className="h-7 w-7 rounded" />
+			<Skeleton className="h-4 w-32" />
+			<div className="flex-1" />
+			<Skeleton className="h-8 w-8 rounded-full" />
+		</div>
+		<div className="flex h-full flex-col-reverse overflow-hidden">
+			<div className="px-4">
+				<div className="mx-auto w-full max-w-3xl py-6">
+					<div className="flex flex-col gap-3">
+						{/* User message bubble (right-aligned) */}
+						<div className="flex w-full justify-end">
+							<Skeleton className="h-10 w-2/3 rounded-lg" />
+						</div>
+						{/* Assistant response lines (left-aligned) */}
+						<div className="space-y-3">
+							<Skeleton className="h-4 w-full" />
+							<Skeleton className="h-4 w-5/6" />
+							<Skeleton className="h-4 w-4/6" />
+						</div>
+						{/* Second user message bubble */}
+						<div className="mt-3 flex w-full justify-end">
+							<Skeleton className="h-10 w-1/2 rounded-lg" />
+						</div>
+						{/* Second assistant response */}
+						<div className="space-y-3">
+							<Skeleton className="h-4 w-full" />
+							<Skeleton className="h-4 w-5/6" />
+							<Skeleton className="h-4 w-4/6" />
+							<Skeleton className="h-4 w-full" />
+							<Skeleton className="h-4 w-3/5" />
+						</div>
 					</div>
 				</div>
 			</div>
diff --git a/site/src/pages/AgentsPage/DiffRightPanel.tsx b/site/src/pages/AgentsPage/DiffRightPanel.tsx
index 1f9a35b9af..2489ac2a17 100644
--- a/site/src/pages/AgentsPage/DiffRightPanel.tsx
+++ b/site/src/pages/AgentsPage/DiffRightPanel.tsx
@@ -1,6 +1,6 @@
 import {
+	type ReactNode,
 	type PointerEvent as ReactPointerEvent,
-	type Ref,
 	useCallback,
 	useEffect,
 	useRef,
@@ -29,17 +29,16 @@ function loadPersistedWidth(): number {
 }
 
 interface DiffRightPanelProps {
-	ref?: Ref<HTMLDivElement>;
 	isOpen: boolean;
+	children?: ReactNode;
 }
 
 /**
- * The right-side panel for the diff/files-changed view. Always mounted
- * so the portal ref is always available (fixes blank-on-reopen). When
- * closed the panel is hidden via CSS and takes no layout space. On xl+
+ * The right-side panel for the diff/files-changed view. When closed
+ * the panel is hidden via CSS and takes no layout space. On xl+
  * screens the panel is horizontally resizable via a drag handle.
  */
-export const DiffRightPanel = ({ ref, isOpen }: DiffRightPanelProps) => {
+export const DiffRightPanel = ({ isOpen, children }: DiffRightPanelProps) => {
 	const [width, setWidth] = useState(loadPersistedWidth);
 	const isDragging = useRef(false);
 	const startX = useRef(0);
@@ -93,7 +92,6 @@ export const DiffRightPanel = ({ ref, isOpen }: DiffRightPanelProps) => {
 
 	return (
 		<div
-			ref={ref}
 			data-testid="agents-detail-right-panel"
 			style={
 				isOpen
@@ -103,7 +101,7 @@ export const DiffRightPanel = ({ ref, isOpen }: DiffRightPanelProps) => {
 			className={cn(
 				"relative min-h-0 min-w-0 border-t border-border-default bg-surface-primary",
 				isOpen
-					? "h-[42dvh] min-h-[260px] max-h-[56dvh] xl:h-auto xl:max-h-none xl:w-[var(--panel-width)] xl:min-w-[360px] xl:max-w-[960px] xl:border-l xl:border-t-0"
+					? "flex h-[42dvh] min-h-[260px] max-h-[56dvh] flex-col xl:h-auto xl:max-h-none xl:w-[var(--panel-width)] xl:min-w-[360px] xl:max-w-[960px] xl:border-l xl:border-t-0"
 					: "hidden",
 			)}
 		>
@@ -114,6 +112,7 @@ export const DiffRightPanel = ({ ref, isOpen }: DiffRightPanelProps) => {
 				onPointerUp={handlePointerUp}
 				className="absolute top-0 left-0 z-10 hidden h-full w-1 cursor-col-resize select-none transition-colors hover:bg-content-link xl:block"
 			/>
+			{children}
 		</div>
 	);
 };