feat: show research chat history as full-width tabs

README.md

@@ -201,7 +201,7 @@ available. The backend handles tools even when the browser is closed.
 Use **New chat** to leave the current conversation and start a fresh Codex
 thread with your next message. The open deck and host reports remain available.
 A running turn continues in the background when you open another chat.
-Selection belongs to the current URL; another browser does not change it. **Chat history** reopens saved conversations with their account
+Selection belongs to the current URL; another browser does not change it. **Chat history** appears as a horizontally scrollable tab strip above the chat and deck, with a **+** button for a new chat. Tabs reopen saved conversations with their account
 selection, deck and citations; the next message resumes the same Codex thread.
 SQLite stores conversation snapshots. Active selection is not stored globally.
 Each turn is limited to 6 columns, 12 upstream requests shared between list

e2e/integrations/research.test.ts

@@ -347,6 +347,17 @@ test("keeps browser conversation selection independent and restores it on reload
     const secondWorkspace = new WorkspacePage(secondPage);
     await researchPage.goTo(`?run=${first}`, { waitUntil: "domcontentloaded" });
     await workspacePage.showResearch();
+    const history = page.getByRole("navigation", { name: "Chat history" });
+    const firstTab = history.getByRole("button", { name: "Browser one conversation" });
+    const secondTab = history.getByRole("button", { name: "Browser two conversation" });
+    await expect(firstTab).toHaveAttribute("aria-current", "page");
+    await workspacePage.showDeckManagement();
+    await secondTab.click();
+    await expect(page).toHaveURL(new RegExp(`run=${second}`));
+    await expect(secondTab).toHaveAttribute("aria-current", "page");
+    await expect(researchPage.conversation).toContainText("Browser two conversation");
+    await page.goBack();
+    await expect(firstTab).toHaveAttribute("aria-current", "page");
     await secondResearch.goTo(`?run=${second}`, {
       waitUntil: "domcontentloaded",
     });

e2e/integrations/workspace.test.ts

@@ -13,6 +13,20 @@ test("keeps the sidebar, composer and deck reachable at compact widths", async (
     await workspacePage.showResearch();
     const chat = researchPage.panel;
     await expect(chat).toBeVisible();
+    const history = page.getByRole("navigation", { name: "Chat history" });
+    await expect(history).toBeVisible();
+    const historyBounds = await history.boundingBox();
+    const chatBounds = await chat.boundingBox();
+    if (!historyBounds || !chatBounds) throw new Error("Chat and history must have visible bounds");
+    expect(historyBounds.x).toBe(0);
+    const availableWidth =
+      width < 768
+        ? await page
+            .getByRole("dialog", { name: "Workspace" })
+            .evaluate((element) => element.clientWidth)
+        : width;
+    expect(historyBounds.width).toBe(availableWidth);
+    expect(historyBounds.y + historyBounds.height).toBeLessThanOrEqual(chatBounds.y);
     const composer = researchPage.composer;
     await expect(composer).toBeVisible();
     const bounds = await composer.boundingBox();

src/components/app-shell.tsx

@@ -15,6 +15,7 @@ import { WorkspaceNavigation } from "#/components/workspace-navigation";
 type ShellProps = {
   hasTemporaryDecks: boolean;
   sidebar: ReactNode;
+  researchHistory: (onSelect: () => void) => ReactNode;
   researchChat: (closeMobileSidebar: () => void) => ReactNode;
   children: ReactNode;
 };
@@ -22,16 +23,27 @@ type ShellProps = {
 export function AppShell(props: ShellProps) {
   return (
     <TooltipProvider delay={800}>
-      <SidebarProvider className="h-dvh min-h-0 overflow-hidden [--sidebar-width:25rem] [--sidebar-width-icon:4rem]">
+      <SidebarProvider className="h-dvh min-h-0 flex-col overflow-hidden [--sidebar-width:25rem] [--sidebar-width-icon:4rem]">
         <Workspace {...props} />
       </SidebarProvider>
     </TooltipProvider>
   );
 }
 
-function Workspace({ sidebar, researchChat, children, hasTemporaryDecks }: ShellProps) {
+function Workspace({
+  sidebar,
+  researchChat,
+  researchHistory,
+  children,
+  hasTemporaryDecks,
+}: ShellProps) {
   const [panel, setPanel] = useState<"chat" | "decks">("chat");
-  const { setOpen, setOpenMobile, isMobile } = useSidebar();
+  const { setOpen, setOpenMobile, isMobile, openMobile } = useSidebar();
+  const history = researchHistory(() => {
+    setPanel("chat");
+    if (isMobile) setOpenMobile(true);
+    else setOpen(true);
+  });
   const navigation = [
     { id: "chat", title: "Research chat", icon: MessageSquare },
     { id: "decks", title: "Deck manager", icon: Columns3 },
@@ -39,10 +51,12 @@ function Workspace({ sidebar, researchChat, children, hasTemporaryDecks }: Shell
 
   return (
     <>
-      <Sidebar
+      {(!isMobile || !openMobile) && history}
-        collapsible="icon"
+      <div className="relative flex min-h-0 min-w-0 flex-1">
-        className="overflow-hidden transition-none *:data-[sidebar=sidebar]:flex-row"
+        <Sidebar collapsible="icon" className="absolute! h-full overflow-hidden transition-none">
-      >
+          <div className="flex h-full w-full min-w-0 flex-col">
+            {isMobile && openMobile && history}
+            <div className="flex min-h-0 flex-1">
               <WorkspaceNavigation
                 hasTemporaryDecks={hasTemporaryDecks}
                 footer={
@@ -77,20 +91,27 @@ function Workspace({ sidebar, researchChat, children, hasTemporaryDecks }: Shell
                   </SidebarMenuItem>
                 ))}
               </WorkspaceNavigation>
-        <Sidebar collapsible="none" className="min-w-0 flex-1 group-data-[collapsible=icon]:hidden">
+              <Sidebar
+                collapsible="none"
+                className="min-w-0 flex-1 group-data-[collapsible=icon]:hidden"
+              >
                 <div className={panel === "chat" ? "flex min-h-0 flex-1 flex-col" : "hidden"}>
                   {researchChat(() => setOpenMobile(false))}
                 </div>
                 <section
                   aria-label="Deck manager"
                   className={
-              panel === "decks" ? "flex min-h-0 flex-1 flex-col overflow-y-auto p-4" : "hidden"
+                    panel === "decks"
+                      ? "flex min-h-0 flex-1 flex-col overflow-y-auto p-4"
+                      : "hidden"
                   }
                 >
                   <h2 className="mb-4 text-base font-semibold">Decks</h2>
                   <div className="flex flex-col gap-4">{sidebar}</div>
                 </section>
               </Sidebar>
+            </div>
+          </div>
         </Sidebar>
         <SidebarInset className="min-w-0 overflow-hidden">
           <header className="flex h-12 shrink-0 items-center gap-2 border-b px-3">
@@ -105,6 +126,7 @@ function Workspace({ sidebar, researchChat, children, hasTemporaryDecks }: Shell
             {children}
           </section>
         </SidebarInset>
+      </div>
     </>
   );
 }

src/components/ui/button.tsx

@@ -14,6 +14,7 @@ const buttonVariants = cva(
           "bg-secondary text-secondary-foreground hover:bg-[color-mix(in_oklch,var(--secondary),var(--foreground)_5%)] aria-expanded:bg-secondary aria-expanded:text-secondary-foreground",
         ghost:
           "hover:bg-muted hover:text-foreground aria-expanded:bg-muted aria-expanded:text-foreground dark:hover:bg-muted/50",
+        tab: "rounded-b-none border-b-2 text-muted-foreground hover:bg-muted hover:text-foreground aria-[current=page]:border-b-primary aria-[current=page]:bg-background aria-[current=page]:text-foreground",
         destructive:
           "bg-destructive/10 text-destructive hover:bg-destructive/20 focus-visible:border-destructive/40 focus-visible:ring-destructive/20 dark:bg-destructive/20 dark:hover:bg-destructive/30 dark:focus-visible:ring-destructive/40",
         link: "text-primary underline-offset-4 hover:underline",
@@ -24,6 +25,7 @@ const buttonVariants = cva(
         xs: "h-6 gap-1 rounded-[min(var(--radius-md),10px)] px-2 text-xs in-data-[slot=button-group]:rounded-lg has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*='size-'])]:size-3",
         sm: "h-7 gap-1 rounded-[min(var(--radius-md),12px)] px-2.5 text-[0.8rem] in-data-[slot=button-group]:rounded-lg has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*='size-'])]:size-3.5",
         lg: "h-9 gap-1.5 px-2.5 has-data-[icon=inline-end]:pr-2 has-data-[icon=inline-start]:pl-2",
+        tab: "h-10 w-48 min-w-24 justify-start px-3",
         icon: "size-8",
         "icon-xs":
           "size-6 rounded-[min(var(--radius-md),10px)] in-data-[slot=button-group]:rounded-lg [&_svg:not([class*='size-'])]:size-3",

src/features/decks/deck-page.tsx

@@ -153,10 +153,11 @@ export function DeckPage() {
         if (activate) clearEditors();
       }}
     >
-      {(renderResearchPanel) => (
+      {(renderResearchPanel, researchHistory) => (
         <AppShell
           hasTemporaryDecks={workspace.decks.some((deck) => !deck.persisted)}
           researchChat={renderResearchPanel}
+          researchHistory={researchHistory}
           sidebar={
             <>
               <DeckSwitcher

src/features/research/research-panel.test.tsx

@@ -117,7 +117,12 @@ function show(connections = [connection], ready = true) {
         onOpenDeck={onOpenDeck}
         onNavigateCitation={onNavigateCitation}
       >
-        {(renderPanel) => <div key={presentation}>{renderPanel()}</div>}
+        {(renderPanel, renderHistory) => (
+          <div key={presentation}>
+            {renderHistory()}
+            {renderPanel()}
+          </div>
+        )}
       </ResearchPanel>
     </QueryClientProvider>
   );
@@ -592,9 +597,7 @@ it("opens a saved chat with its context deck and selected accounts, preserving l
   fireEvent.change(screen.getByLabelText("Message"), {
     target: { value: "別の下書き" },
   });
-  fireEvent.change(screen.getByLabelText("Chat history"), {
+  fireEvent.click(screen.getByRole("button", { name: "以前の調査" }));
-    target: { value: saved.id },
-  });
   expect(await screen.findByText("保存した会話")).toBeVisible();
   fireEvent.click(screen.getByRole("link", { name: "前回の引用" }));
   expect(view.onNavigateCitation).toHaveBeenCalledWith(
@@ -659,7 +662,11 @@ it("restores a context-only chat on reload and permits browsing history during a
   };
   const view = show();
   await waitFor(() => expect(view.onOpenDeck).toHaveBeenCalledWith(contextDeck, true));
-  expect(screen.getByLabelText("Chat history")).toBeEnabled();
+  expect(screen.getByRole("button", { name: running.topic })).toBeEnabled();
+  expect(screen.getByRole("button", { name: running.topic })).toHaveAttribute(
+    "aria-current",
+    "page",
+  );
 });
 
 it("keeps newer scoped stream state when the selected chat fetch arrives late", async () => {
@@ -682,9 +689,7 @@ it("keeps newer scoped stream state when the selected chat fetch arrives late",
       : Promise.resolve(current),
   );
   const view = show();
-  fireEvent.change(await screen.findByLabelText("Chat history"), {
+  fireEvent.click(await screen.findByRole("button", { name: "Saved chat" }));
-    target: { value: saved.id },
-  });
   await waitFor(() => expect(MockEventSource.instances).toHaveLength(2));
   expect(MockEventSource.instances[0]?.close).toHaveBeenCalledOnce();
   expect(MockEventSource.instances[1]?.url).toBe("/api/research/events?run=saved");

src/features/research/research-panel.tsx

@@ -1,6 +1,6 @@
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { useServerFn } from "@tanstack/react-start";
-import { ArrowUpIcon, SquareIcon } from "lucide-react";
+import { ArrowUpIcon, PlusIcon, SquareIcon } from "lucide-react";
 import { type ReactNode, useCallback, useEffect, useId, useRef, useState } from "react";
 import { Bubble, BubbleContent } from "#/components/ui/bubble";
 import { Button } from "#/components/ui/button";
@@ -23,7 +23,6 @@ import {
   MessageScrollerProvider,
   MessageScrollerViewport,
 } from "#/components/ui/message-scroller";
-import { NativeSelect, NativeSelectOption } from "#/components/ui/native-select";
 import type { Connection } from "../connections/model";
 import type { Deck } from "../decks/model";
 import { useUrlState } from "../navigation/use-url-state";
@@ -51,6 +50,7 @@ type ResearchDraft = {
   selected: string[] | null;
 };
 type RenderResearchPanel = (onCitationNavigated?: () => void) => ReactNode;
+type RenderResearchHistory = (onSelect?: () => void) => ReactNode;
 
 export function ResearchPanel({
   ready,
@@ -65,14 +65,13 @@ export function ResearchPanel({
   connections: Connection[];
   onOpenDeck: (deck: Deck, activate?: boolean) => unknown;
   onNavigateCitation?: (url: string, citations: ResearchCitation[], restore?: boolean) => boolean;
-  children?: (renderPanel: RenderResearchPanel) => ReactNode;
+  children?: (renderPanel: RenderResearchPanel, renderHistory: RenderResearchHistory) => ReactNode;
 }) {
   const [search, setSearch] = useUrlState();
   const fetchStatus = useServerFn(loadResearchStatus);
   const start = useServerFn(startResearch);
   const cancel = useServerFn(cancelResearch);
   const client = useQueryClient();
-  const historyId = useId();
   const selectedId = search.run === "new" ? undefined : search.run;
   const selection = useRef(selectedId);
   useEffect(() => {
@@ -292,6 +291,57 @@ export function ResearchPanel({
     }
   }
 
+  const renderHistory: RenderResearchHistory = (onSelect) => (
+    <nav
+      aria-label="Chat history"
+      data-testid="research-history"
+      className="flex h-12 min-w-0 shrink-0 items-stretch border-b bg-sidebar"
+    >
+      <div className="flex min-w-0 flex-1 items-end gap-1 overflow-x-auto px-2 pt-2">
+        {status.data?.history?.map((entry) => (
+          <Button
+            key={entry.id}
+            type="button"
+            variant="tab"
+            size="tab"
+            aria-current={entry.id === selectedId ? "page" : undefined}
+            title={entry.title}
+            disabled={busy}
+            onClick={() => {
+              selectChat(entry.id);
+              onSelect?.();
+            }}
+          >
+            <span className="truncate">{entry.title}</span>
+          </Button>
+        ))}
+        {!selectedId && (
+          <span
+            className="flex h-10 w-48 shrink-0 items-center rounded-t-lg border-b-2 border-primary bg-background px-3 text-sm font-medium"
+            aria-current="page"
+          >
+            New chat
+          </span>
+        )}
+      </div>
+      <Button
+        variant="ghost"
+        size="icon"
+        type="button"
+        className="mx-2 self-center"
+        aria-label="New chat"
+        title="New chat"
+        disabled={busy || !run}
+        onClick={() => {
+          newChat();
+          onSelect?.();
+        }}
+      >
+        <PlusIcon />
+      </Button>
+    </nav>
+  );
+
   const renderPanel: RenderResearchPanel = (onCitationNavigated) => (
     <aside
       data-testid="research-panel"
@@ -303,34 +353,6 @@ export function ResearchPanel({
         className="flex shrink-0 flex-wrap items-center justify-between gap-2 border-b p-4"
       >
         <h2 className="m-0 text-base">Research chat</h2>
-        <Button variant="ghost" size="sm" type="button" disabled={busy || !run} onClick={newChat}>
-          New chat
-        </Button>
-        {(status.data?.history?.length ?? 0) > 0 && (
-          <label
-            data-testid="research-history"
-            className="flex w-full min-w-0 items-center gap-2 text-research-label text-muted-foreground [&>[data-slot=native-select-wrapper]]:min-w-0 [&>[data-slot=native-select-wrapper]]:flex-1"
-            htmlFor={historyId}
-          >
-            <span className="shrink-0">Chat history</span>
-            <NativeSelect
-              id={historyId}
-              size="sm"
-              value={run?.id ?? ""}
-              disabled={busy}
-              onChange={(event) => selectChat(event.target.value)}
-            >
-              <NativeSelectOption value="" disabled>
-                New chat
-              </NativeSelectOption>
-              {status.data?.history?.map((entry) => (
-                <NativeSelectOption key={entry.id} value={entry.id}>
-                  {entry.title}
-                </NativeSelectOption>
-              ))}
-            </NativeSelect>
-          </label>
-        )}
       </header>
       {reconnecting && (
         <p
@@ -410,7 +432,14 @@ export function ResearchPanel({
       />
     </aside>
   );
-  return children ? children(renderPanel) : renderPanel();
+  return children ? (
+    children(renderPanel, renderHistory)
+  ) : (
+    <>
+      {renderHistory()}
+      {renderPanel()}
+    </>
+  );
 }
 
 function ResearchConversation({