FN-7450: collapse mobile chat header rows

Collapse the mobile direct chat header into the shared top row.

- Move the mobile direct-thread back button and session switcher into ViewHeader actions.
- Hide the redundant mobile thread header while preserving desktop thread identity and context details.
- Update mobile chat styling, docs, changeset, and header contract tests for the single-row layout.

Files changed:
 .changeset/fn-7450-mobile-chat-header.md           |   7 +
 docs/dashboard-guide.md                            |   3 +-
 packages/dashboard/app/components/ChatView.css     |  53 +++++-
 packages/dashboard/app/components/ChatView.tsx     | 197 +++++++++++----------
 .../__tests__/ChatView.core-contracts.test.tsx     |  48 ++---
 .../components/__tests__/ChatView.mobile.test.tsx  |  76 ++++++--
 6 files changed, 256 insertions(+), 128 deletions(-)

Fusion-Task-Id: FN-7450

Fusion-Task-Lineage: c266a9b8-7fb1-410e-9c35-adad4c6a2d47

Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>

.changeset/fn-7450-mobile-chat-header.md

@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Collapse mobile Chat thread controls into one compact header row.
+category: feature
+dev: Mobile direct-chat moves back/session controls into ViewHeader and floats the Markdown/plain toggle.

docs/dashboard-guide.md

@@ -411,7 +411,8 @@ Chat view provides project-scoped conversations with agents.
 - If you queue follow-up user messages while the assistant is still streaming, Chat persists them per session, stacks each queued preview above the input box with one shared divider, and restores/sends them one at a time in FIFO order once each active response finishes if you leave and return.
 - Chat message lists now track near-bottom scroll state: while you are reading older messages, live streaming/new replies do not force-scroll; a **Latest** jump control appears until you return to the tail.
 - On mobile direct-chat threads, entering a thread and restoring Chat after tab/page visibility returns re-anchors to the newest message (`scrollTop = scrollHeight`) so the view always opens at the live tail.
-- On mobile direct-chat threads, tapping the active title/identity in the thread header opens a lightweight conversation dropdown so you can switch to another direct session or start a New Chat without backing out to the sidebar list first; long conversation titles now stay readable in the dropdown via wrapped option text and taller touch-friendly rows.
+- On mobile direct-chat threads, the top Chat header collapses into one compact row: the back button and active conversation dropdown live beside the Chat icon, while the visible “Chat” title is hidden to preserve transcript space. Tapping the active conversation opens a lightweight dropdown so you can switch to another direct session or start a New Chat without backing out to the sidebar list first; long conversation titles stay readable in the dropdown via wrapped option text and taller touch-friendly rows.
+- On mobile direct-chat threads, the single thread-wide Markdown/plain eye toggle floats above the transcript/composer area instead of occupying a second header row; desktop/tablet keeps the toggle in the thread header.
 - Direct chat sessions can be renamed from the sidebar row edit button, the desktop conversation context menu, and the mobile session switcher; blank rename submissions clear the custom title so the default session label is shown again.
 <!-- FNXC:ChatViewDocs 2026-07-01-00:00: Task-detail planner chats are intentionally hidden from the common Direct feed by default after issue #1850; Settings keeps an opt-in for operators who want populated task-planner sessions restored without adding a mandatory Tasks tab. -->
 <!-- FNXC:TaskDetailPlannerChat 2026-07-01-22:02: Done-task planner Chat remains available for retrospective Q&A and can create a task-scoped refinement through the planner tool, while common Chat feed visibility remains opt-in. -->

packages/dashboard/app/components/ChatView.css

@@ -768,6 +768,33 @@ Mobile chat session switching needs a dedicated rename tap target beside each se
   min-width: 0;
 }
 
+/*
+FNXC:ChatHeader 2026-07-02-00:00:
+Mobile direct-chat detail uses ViewHeader as the only visible header row. Keep the Chat icon/title relationship available to assistive tech while visually collapsing only the text label, and let the moved session switcher consume the action row width without duplicating the old thread-header controls.
+*/
+.chat-view--mobile-direct-thread > .view-header .view-header__title span {
+  position: absolute;
+  inline-size: var(--btn-border-width);
+  block-size: var(--btn-border-width);
+  margin: calc(var(--btn-border-width) * -1);
+  overflow: hidden;
+  clip-path: inset(50%);
+  white-space: nowrap;
+}
+
+.chat-view--mobile-direct-thread > .view-header .view-header__actions {
+  flex: 1 1 auto;
+  justify-content: flex-start;
+}
+
+.chat-view--mobile-direct-thread .chat-back-btn {
+  flex: 0 0 auto;
+}
+
+.chat-view--mobile-direct-thread .chat-mobile-session-menu {
+  flex: 1 1 auto;
+}
+
 @media (max-width: 768px), (max-height: 480px) {
   .chat-view-header-scope-toggle {
     flex-basis: clamp(112px, 42vw, 180px);
@@ -911,9 +938,10 @@ In the narrow/mobile chat layout there is no room for an expand/maximize afforda
   }
 }
 
-/* Single thread-wide markdown / plain-text toggle, anchored to the right of
+/*
- * the header next to "New Chat". Replaces the per-message eye toggle that
+FNXC:ChatRenderMode 2026-07-02-00:00:
- * used to live inside every assistant bubble. */
+Chat keeps one thread-wide Markdown/plain control: desktop/tablet anchors it in the thread identity header, while mobile direct-thread view floats the same button above the transcript/composer so it does not reintroduce a second header row or per-message toggles.
+*/
 .chat-thread-header-render-toggle {
   margin-left: auto;
   flex-shrink: 0;
@@ -948,6 +976,25 @@ In the narrow/mobile chat layout there is no room for an expand/maximize afforda
   color: var(--text);
 }
 
+.chat-thread-header-render-toggle--floating {
+  position: absolute;
+  right: var(--space-md);
+  bottom: calc((var(--space-lg) * 2.5) + (var(--space-md) * 2) + var(--space-sm));
+  z-index: 3;
+  width: calc(var(--space-lg) * 2.25);
+  height: calc(var(--space-lg) * 2.25);
+  min-width: calc(var(--space-lg) * 2.25);
+  min-height: calc(var(--space-lg) * 2.25);
+  border: var(--btn-border-width) solid var(--border);
+  border-radius: var(--radius-full);
+  background: var(--surface);
+  box-shadow: var(--shadow-md);
+}
+
+.chat-thread-header-render-toggle--floating:hover {
+  background: var(--surface-hover);
+}
+
 /* Messages */
 .chat-messages {
   flex: 1 1 auto;

packages/dashboard/app/components/ChatView.tsx

@@ -2151,6 +2151,7 @@ export function ChatView({ projectId, addToast, floating = false, compactLayout
     })
     : null;
   const showMobileSessionSwitcher = isChatMobile && chatScope === "direct" && !!activeSession;
+  const showMobileDirectThreadHeaderControls = isChatMobile && chatScope === "direct" && hasThreadInView;
 
   const agentName =
     agentsMap.get(activeSession?.agentId ?? "")?.name ||
@@ -2578,6 +2579,71 @@ export function ChatView({ projectId, addToast, floating = false, compactLayout
   FNXC:ChatHeader 2026-06-22-18:44:
   Very narrow chat headers collapse Direct/Rooms to icons while retaining aria-selected tabs and text labels for wider headers. The segmented control must stay height-aligned with the ViewHeader action row, so icon+label markup is stable and CSS hides only the label.
   */
+  const mobileDirectSessionSwitcher = showMobileSessionSwitcher ? (
+    <div className="chat-mobile-session-menu" ref={mobileSessionMenuRef}>
+      <button
+        type="button"
+        className="btn chat-mobile-session-trigger"
+        data-testid="chat-mobile-session-trigger"
+        aria-haspopup="menu"
+        aria-expanded={mobileSessionMenuOpen}
+        onClick={() => setMobileSessionMenuOpen((open) => !open)}
+      >
+        {activeModelProvider ? <ProviderIcon provider={activeModelProvider} size="md" /> : <Bot size={16} />}
+        <span className="chat-thread-header-title">{threadHeaderTitle}</span>
+        {showThreadHeaderModelTag && <span className="chat-model-tag">{activeModelTag}</span>}
+        <ChevronDown size={16} aria-hidden="true" />
+      </button>
+      {mobileSessionMenuOpen && (
+        <div className="chat-mobile-session-dropdown" role="menu" data-testid="chat-mobile-session-dropdown">
+          {filteredSessions.map((session) => (
+            <div
+              key={session.id}
+              className={`chat-mobile-session-option-row${activeSession?.id === session.id ? " chat-mobile-session-option-row--active" : ""}`}
+              role="none"
+            >
+              <button
+                type="button"
+                role="menuitem"
+                className={`chat-mobile-session-option${activeSession?.id === session.id ? " chat-mobile-session-option--active" : ""}`}
+                data-testid={`chat-mobile-session-option-${session.id}`}
+                onClick={() => handleSessionClick(session.id)}
+              >
+                <span className="chat-mobile-session-option-title">{session.title || t("chat.untitledSession", "Untitled")}</span>
+              </button>
+              <button
+                type="button"
+                className="btn-icon chat-mobile-session-rename"
+                data-testid={`chat-mobile-session-rename-${session.id}`}
+                aria-label={t("chat.renameConversationAria", "Rename conversation {{title}}", { title: session.title || t("chat.untitledSession", "Untitled") })}
+                onClick={() => openRenameDialog(session.id)}
+              >
+                <Pencil size={14} />
+              </button>
+            </div>
+          ))}
+          {/*
+          FNXC:Chat 2026-06-27-00:00:
+          Mobile Direct-scope quick session switching must let users start a new chat without leaving the open thread. Route this affordance through the same setShowNewDialog(true) / NewChatDialog path as the header and sidebar-footer controls.
+          */}
+          <button
+            type="button"
+            role="menuitem"
+            className="chat-mobile-session-new"
+            data-testid="chat-mobile-session-new"
+            onClick={() => {
+              setMobileSessionMenuOpen(false);
+              setShowNewDialog(true);
+            }}
+          >
+            <Plus size={16} aria-hidden="true" />
+            <span>{t("chat.newChat", "New Chat")}</span>
+          </button>
+        </div>
+      )}
+    </div>
+  ) : null;
+
   const scopeToggle = chatRoomsEnabled ? (
     <div className="chat-sidebar-scope-toggle chat-view-header-scope-toggle" role="tablist" data-testid="chat-sidebar-scope-toggle">
       <button
@@ -2610,13 +2676,26 @@ export function ChatView({ projectId, addToast, floating = false, compactLayout
     FNXC:Chat 2026-06-22-12:55:
     Chat uses the shared ViewHeader so its page chrome matches the other main-content views. The height-sensitive two-pane chat layout remains isolated in .chat-view__body beneath that header, preserving sidebar resize, thread scrolling, and mobile keyboard compensation while moving the desktop New Chat action into the canonical header actions cluster.
     */
-    <div ref={chatViewRef} className={`chat-view${floating ? " chat-view--floating" : ""}${isChatMobile ? " chat-view--narrow" : ""}`}>
+    <div ref={chatViewRef} className={`chat-view${floating ? " chat-view--floating" : ""}${isChatMobile ? " chat-view--narrow" : ""}${showMobileDirectThreadHeaderControls ? " chat-view--mobile-direct-thread" : ""}`}>
       <ViewHeader
         icon={MessageSquare}
         title={t("chat.title", "Chat")}
         actions={
           <>
-            {scopeToggle}
+            {showMobileDirectThreadHeaderControls ? (
+              <>
+                {/*
+                FNXC:ChatHeader 2026-07-02-00:00:
+                Mobile direct-thread view has a single top row: move back navigation and the active conversation switcher into ViewHeader so the transcript gains the height formerly consumed by a second thread header. The ViewHeader still owns the accessible Chat title; CSS only hides its visible text in this direct-thread mobile state.
+                */}
+                <button className="btn-icon chat-back-btn" onClick={handleBack} data-testid="chat-back-btn" aria-label={t("chat.backToConversations", "Back to conversations")}>
+                  <ChevronLeft size={16} />
+                </button>
+                {mobileDirectSessionSwitcher}
+              </>
+            ) : (
+              scopeToggle
+            )}
             {!isChatMobile ? (
               <button
                 className="btn btn-sm btn-primary chat-view-header-new-chat"
@@ -3283,95 +3362,23 @@ export function ChatView({ projectId, addToast, floating = false, compactLayout
         </div>
       ) : (
       <div ref={chatThreadRef} className="chat-thread">
-        {/* Header - always rendered in desktop/tablet, only rendered in mobile when viewing a thread */}
+        {/* Header - desktop/tablet keeps the thread identity row; mobile direct-thread controls move into ViewHeader. */}
-        {(hasThreadInView || !isChatMobile) && (
+        {!isChatMobile && (hasThreadInView || !isChatMobile) && (
           <div className="chat-thread-header">
-            {isChatMobile && hasThreadInView && (
-              <button className="btn-icon" onClick={handleBack} data-testid="chat-back-btn">
-                <ChevronLeft size={16} />
-              </button>
-            )}
             <div className="chat-thread-header-identity" data-testid="chat-thread-header-identity">
-              {showMobileSessionSwitcher ? (
+              {activeModelProvider ? <ProviderIcon provider={activeModelProvider} size="md" /> : <Bot size={16} />}
-                <div className="chat-mobile-session-menu" ref={mobileSessionMenuRef}>
+              <span className="chat-thread-header-title">{threadHeaderTitle}</span>
-                  <button
+              {showThreadHeaderModelTag && <span className="chat-model-tag">{activeModelTag}</span>}
-                    type="button"
+              {showThreadHeaderContextWindow && threadHeaderContextTotal && threadHeaderContextLabel ? (
-                    className="btn chat-mobile-session-trigger"
+                <span
-                    data-testid="chat-mobile-session-trigger"
+                  className="chat-thread-header-context"
-                    aria-haspopup="menu"
+                  data-testid="chat-thread-context-window"
-                    aria-expanded={mobileSessionMenuOpen}
+                  title={threadHeaderContextLabel}
-                    onClick={() => setMobileSessionMenuOpen((open) => !open)}
+                  aria-label={threadHeaderContextLabel}
-                  >
+                >
-                    {activeModelProvider ? <ProviderIcon provider={activeModelProvider} size="md" /> : <Bot size={16} />}
+                  {threadHeaderContextUsed} / {threadHeaderContextTotal}
-                    <span className="chat-thread-header-title">{threadHeaderTitle}</span>
+                </span>
-                    {showThreadHeaderModelTag && <span className="chat-model-tag">{activeModelTag}</span>}
+              ) : null}
-                    <ChevronDown size={16} aria-hidden="true" />
-                  </button>
-                  {mobileSessionMenuOpen && (
-                    <div className="chat-mobile-session-dropdown" role="menu" data-testid="chat-mobile-session-dropdown">
-                      {filteredSessions.map((session) => (
-                        <div
-                          key={session.id}
-                          className={`chat-mobile-session-option-row${activeSession?.id === session.id ? " chat-mobile-session-option-row--active" : ""}`}
-                          role="none"
-                        >
-                          <button
-                            type="button"
-                            role="menuitem"
-                            className={`chat-mobile-session-option${activeSession?.id === session.id ? " chat-mobile-session-option--active" : ""}`}
-                            data-testid={`chat-mobile-session-option-${session.id}`}
-                            onClick={() => handleSessionClick(session.id)}
-                          >
-                            <span className="chat-mobile-session-option-title">{session.title || t("chat.untitledSession", "Untitled")}</span>
-                          </button>
-                          <button
-                            type="button"
-                            className="btn-icon chat-mobile-session-rename"
-                            data-testid={`chat-mobile-session-rename-${session.id}`}
-                            aria-label={t("chat.renameConversationAria", "Rename conversation {{title}}", { title: session.title || t("chat.untitledSession", "Untitled") })}
-                            onClick={() => openRenameDialog(session.id)}
-                          >
-                            <Pencil size={14} />
-                          </button>
-                        </div>
-                      ))}
-                      {/*
-                      FNXC:Chat 2026-06-27-00:00:
-                      Mobile Direct-scope quick session switching must let users start a new chat without leaving the open thread. Route this affordance through the same setShowNewDialog(true) / NewChatDialog path as the header and sidebar-footer controls.
-                      */}
-                      <button
-                        type="button"
-                        role="menuitem"
-                        className="chat-mobile-session-new"
-                        data-testid="chat-mobile-session-new"
-                        onClick={() => {
-                          setMobileSessionMenuOpen(false);
-                          setShowNewDialog(true);
-                        }}
-                      >
-                        <Plus size={16} aria-hidden="true" />
-                        <span>{t("chat.newChat", "New Chat")}</span>
-                      </button>
-                    </div>
-                  )}
-                </div>
-              ) : (
-                <>
-                  {activeModelProvider ? <ProviderIcon provider={activeModelProvider} size="md" /> : <Bot size={16} />}
-                  <span className="chat-thread-header-title">{threadHeaderTitle}</span>
-                  {showThreadHeaderModelTag && <span className="chat-model-tag">{activeModelTag}</span>}
-                  {showThreadHeaderContextWindow && threadHeaderContextTotal && threadHeaderContextLabel ? (
-                    <span
-                      className="chat-thread-header-context"
-                      data-testid="chat-thread-context-window"
-                      title={threadHeaderContextLabel}
-                      aria-label={threadHeaderContextLabel}
-                    >
-                      {threadHeaderContextUsed} / {threadHeaderContextTotal}
-                    </span>
-                  ) : null}
-                </>
-              )}
             </div>
             {hasThreadInView && (
               <button
@@ -3387,6 +3394,18 @@ export function ChatView({ projectId, addToast, floating = false, compactLayout
           </div>
         )}
 
+        {isChatMobile && hasThreadInView && (
+          <button
+            type="button"
+            className={`chat-thread-header-render-toggle chat-thread-header-render-toggle--floating${showAllAsPlain ? " chat-thread-header-render-toggle--plain" : ""}`}
+            data-testid="chat-thread-render-toggle"
+            aria-label={showAllAsPlain ? t("chat.showRenderedMarkdown", "Show all messages as rendered Markdown") : t("chat.showPlainText", "Show all messages as plain text")}
+            onClick={toggleAllAsPlain}
+          >
+            {showAllAsPlain ? <EyeOff size={14} /> : <Eye size={14} />}
+          </button>
+        )}
+
         {/* Messages + composer. CLI-backed chat sessions delegate this
             region to <CliChatSurface> (transcript/raw-terminal toggle +
             queued composer); generic-tier adapters render terminal-only. */}

packages/dashboard/app/components/__tests__/ChatView.core-contracts.test.tsx

@@ -526,52 +526,52 @@ describe("ChatView CSS — active state edge highlights", () => {
 describe("FN-3911 chat session list layout", () => {
   const css = loadAllAppCss();
 
-  it("reserves right padding on title and preview rows so text clears the delete button", async () => {
+  it("reserves right padding on title and preview rows so text clears the edit/delete action pair", async () => {
     const titleMatch = css.match(/\.chat-session-title\s*\{([^}]*)\}/);
     const previewMatch = css.match(/\.chat-session-preview\s*\{([^}]*)\}/);
     expect(titleMatch).toBeTruthy();
     expect(previewMatch).toBeTruthy();
-    expect(titleMatch?.[1]).toMatch(/padding-right:\s*calc\(var\(--space-md\)\s*\*\s*3\)/);
+    expect(titleMatch?.[1]).toContain("padding-right: calc((var(--space-md) * 4) + (var(--space-xs) * 2))");
-    expect(previewMatch?.[1]).toMatch(/padding-right:\s*calc\(var\(--space-md\)\s*\*\s*3\)/);
+    expect(previewMatch?.[1]).toContain("padding-right: calc((var(--space-md) * 4) + (var(--space-xs) * 2))");
   });
 
-  it("FN-4385: keeps mobile title/preview clearance matched to compact delete button", async () => {
+  it("FN-4385/FN-7441: keeps mobile title/preview clearance matched to compact row action pair", async () => {
     expect(css).toMatch(
-      /@media\s*\(max-width:\s*768px\)[\s\S]*?\.chat-session-title,\s*\.chat-session-preview\s*\{\s*padding-right:\s*calc\(var\(--space-md\)\s*\*\s*3\);\s*\}/,
+      /@media\s*\(max-width:\s*768px\)[\s\S]*?\.chat-session-title,\s*\.chat-session-preview\s*\{\s*padding-right:\s*calc\(\(var\(--space-md\)\s*\*\s*4\)\s*\+\s*\(var\(--space-xs\)\s*\*\s*2\)\);\s*\}/,
     );
   });
 });
 
-describe("Chat Session Delete Button CSS", () => {
+describe("Chat Session Row Action CSS", () => {
   const css = loadAllAppCss();
 
-  it(".chat-session-delete-btn exists with opacity: 0", async () => {
+  it(".chat-session-actions positions the edit/delete pair outside row text flow", async () => {
-    const match = css.match(/\.chat-session-delete-btn\s*\{([^}]*)\}/);
+    const actionsMatch = css.match(/\.chat-session-actions\s*\{([^}]*)\}/);
-    expect(match).toBeTruthy();
+    const actionButtonMatch = css.match(/\.chat-session-action-btn\s*\{([^}]*)\}/);
-    expect(match![1]).toContain("opacity: 0");
+    expect(actionsMatch).toBeTruthy();
+    expect(actionButtonMatch).toBeTruthy();
+    expect(actionsMatch![1]).toContain("position: absolute");
+    expect(actionsMatch![1]).toContain("right: var(--space-sm)");
+    expect(actionsMatch![1]).toContain("gap: var(--space-xs)");
+    expect(actionButtonMatch![1]).toContain("width: calc(var(--space-md) * 2)");
+    expect(actionButtonMatch![1]).toContain("min-height: calc(var(--space-md) * 2)");
   });
 
-  it(".chat-session-item:hover .chat-session-delete-btn has opacity: 1", async () => {
+  it("FN-4352: mobile row action buttons stay compact without min-size inflation", async () => {
-    const match = css.match(/\.chat-session-item:hover\s*\.chat-session-delete-btn\s*\{([^}]*)\}/);
-    expect(match).toBeTruthy();
-    expect(match![1]).toContain("opacity: 1");
-  });
-
-  it("FN-4352: mobile delete button stays visible without min-size inflation", async () => {
     const mobileRegex = /@media[^{]*\(max-width:\s*768px\)[^{]*\{([\s\S]*?)\n\}/g;
     let match;
-    let deleteRule = "";
+    let actionRule = "";
     while ((match = mobileRegex.exec(css)) !== null) {
       const mediaContent = match[1];
-      if (mediaContent.includes(".chat-session-delete-btn")) {
+      if (mediaContent.includes(".chat-session-title")) {
-        deleteRule = mediaContent.match(/\.chat-session-delete-btn\s*\{([^}]*)\}/)?.[1] ?? "";
+        actionRule = mediaContent.match(/\.chat-session-title,\s*\.chat-session-preview\s*\{([^}]*)\}/)?.[1] ?? "";
-        if (deleteRule) break;
+        if (actionRule) break;
       }
     }
 
-    expect(deleteRule).toContain("opacity: 1");
+    expect(actionRule).toContain("padding-right: calc((var(--space-md) * 4) + (var(--space-xs) * 2))");
-    expect(deleteRule).not.toContain("min-width:");
+    expect(actionRule).not.toContain("min-width:");
-    expect(deleteRule).not.toContain("min-height:");
+    expect(actionRule).not.toContain("min-height:");
   });
 });
 

packages/dashboard/app/components/__tests__/ChatView.mobile.test.tsx

@@ -220,14 +220,17 @@ describe("ChatView mobile behavior", () => {
 
       // Thread header should not be rendered when there's no active session
       expect(document.querySelector(".chat-thread-header")).not.toBeInTheDocument();
-      // Back button should not be visible
+      // Back/session controls should not appear before a direct thread is selected; ordinary Chat header remains visible.
       expect(screen.queryByTestId("chat-back-btn")).not.toBeInTheDocument();
+      expect(screen.queryByTestId("chat-mobile-session-trigger")).not.toBeInTheDocument();
+      expect(screen.getByRole("heading", { name: "Chat" })).toBeInTheDocument();
+      expect(document.querySelector(".chat-view--mobile-direct-thread")).not.toBeInTheDocument();
     } finally {
       restoreMatchMedia.mockRestore();
     }
   });
 
-  it("mobile mode: renders thread header with back button when session is active", async () => {
+  it("mobile mode: collapses direct thread controls into the top ViewHeader row", async () => {
     const restoreMatchMedia = mockMobileViewport();
     try {
       setupMockChat({
@@ -237,10 +240,51 @@ describe("ChatView mobile behavior", () => {
 
       await renderWithAct(<ChatView projectId="proj-123" addToast={vi.fn()} />);
 
-      // Thread header should be rendered when there's an active session
+      expect(document.querySelector(".chat-thread-header")).not.toBeInTheDocument();
-      expect(document.querySelector(".chat-thread-header")).toBeInTheDocument();
+      expect(document.querySelector(".chat-view--mobile-direct-thread")).toBeInTheDocument();
-      // Back button should be visible in mobile thread view
+
-      expect(screen.getByTestId("chat-back-btn")).toBeInTheDocument();
+      const viewHeader = document.querySelector(".view-header") as HTMLElement;
+      const backButton = screen.getByTestId("chat-back-btn");
+      const sessionTrigger = screen.getByTestId("chat-mobile-session-trigger");
+      const renderToggle = screen.getByTestId("chat-thread-render-toggle");
+
+      expect(viewHeader).toContainElement(backButton);
+      expect(viewHeader).toContainElement(sessionTrigger);
+      expect(viewHeader).not.toContainElement(renderToggle);
+      expect(renderToggle).toHaveClass("chat-thread-header-render-toggle--floating");
+      expect(screen.getAllByTestId("chat-back-btn")).toHaveLength(1);
+      expect(screen.getAllByTestId("chat-mobile-session-trigger")).toHaveLength(1);
+      expect(screen.getByRole("heading", { name: "Chat" })).toBeInTheDocument();
+    } finally {
+      restoreMatchMedia.mockRestore();
+    }
+  });
+
+  it("mobile mode: floating render toggle flips persisted and streaming assistant output", async () => {
+    const restoreMatchMedia = mockMobileViewport();
+    try {
+      setupMockChat({
+        activeSession: { id: "session-001", agentId: "agent-001", status: "active", title: "Test Chat", createdAt: "2026-04-08T00:00:00.000Z", updatedAt: "2026-04-08T00:00:00.000Z" },
+        messages: [{ id: "msg-001", sessionId: "session-001", role: "assistant", content: "**Persisted** reply", createdAt: "2026-04-08T00:00:00.000Z" }],
+        isStreaming: true,
+        streamingText: "**Live** reply",
+      });
+
+      await renderWithAct(<ChatView projectId="proj-123" addToast={vi.fn()} />);
+
+      const toggle = screen.getByTestId("chat-thread-render-toggle");
+      const persistedBubble = screen.getByTestId("chat-message-msg-001");
+      const streamingBubble = document.querySelector(".chat-message--streaming") as HTMLElement;
+
+      expect(toggle).toHaveClass("chat-thread-header-render-toggle--floating");
+      expect(screen.queryAllByTestId("chat-message-render-toggle")).toHaveLength(0);
+      expect(within(persistedBubble).getByText("Persisted", { selector: "strong" })).toBeInTheDocument();
+      expect(within(streamingBubble).getByText("Live", { selector: "strong" })).toBeInTheDocument();
+
+      await userEvent.click(toggle);
+
+      expect(within(persistedBubble).getByText(/\*\*Persisted\*\* reply/)).toBeInTheDocument();
+      expect(within(streamingBubble).getByText(/\*\*Live\*\* reply/)).toBeInTheDocument();
     } finally {
       restoreMatchMedia.mockRestore();
     }
@@ -340,7 +384,7 @@ describe("ChatView mobile behavior", () => {
     }
   });
 
-  it("mobile mode: thread header title opens quick session switcher and closes after selection", async () => {
+  it("mobile mode: ViewHeader session trigger opens quick session switcher and closes after selection", async () => {
     const restoreMatchMedia = mockMobileViewport();
     const selectSession = vi.fn();
     try {
@@ -1877,10 +1921,20 @@ describe("ChatView mobile CSS contract", () => {
     expect(css).toMatch(/@media\s*\(max-width:\s*768px\)[\s\S]*?\.chat-message\s*\{[^}]*max-width:\s*100%/);
   });
 
-  it("mobile keeps thread-header identity and render toggle inline", async () => {
+  it("mobile direct thread collapses header text and floats the render toggle with tokenized sizing", async () => {
-    expect(css).toMatch(/@media\s*\(max-width:\s*768px\)[\s\S]*?\.chat-thread-header\s*\{[^}]*flex-wrap:\s*nowrap/);
+    const directTitleRule = css.match(/\.chat-view--mobile-direct-thread\s*>\s*\.view-header\s+\.view-header__title\s+span\s*\{([^}]*)\}/)?.[1] ?? "";
-    expect(css).toMatch(/@media\s*\(max-width:\s*768px\)[\s\S]*?\.chat-thread-header-identity\s*\{[^}]*flex:\s*1\s+1\s+auto[^}]*white-space:\s*nowrap/);
+    const actionsRule = css.match(/\.chat-view--mobile-direct-thread\s*>\s*\.view-header\s+\.view-header__actions\s*\{([^}]*)\}/)?.[1] ?? "";
-    expect(css).toMatch(/@media\s*\(max-width:\s*768px\)[\s\S]*?\.chat-thread-header-render-toggle\s*\{[^}]*flex-shrink:\s*0/);
+    const floatingToggleRule = css.match(/\.chat-thread-header-render-toggle--floating\s*\{([^}]*)\}/)?.[1] ?? "";
+
+    expect(directTitleRule).toContain("inline-size: var(--btn-border-width)");
+    expect(directTitleRule).toContain("clip-path: inset(50%)");
+    expect(actionsRule).toContain("flex: 1 1 auto");
+    expect(floatingToggleRule).toContain("position: absolute");
+    expect(floatingToggleRule).toContain("right: var(--space-md)");
+    expect(floatingToggleRule).toContain("bottom: calc((var(--space-lg) * 2.5) + (var(--space-md) * 2) + var(--space-sm))");
+    expect(floatingToggleRule).toContain("min-width: calc(var(--space-lg) * 2.25)");
+    expect(floatingToggleRule).toContain("min-height: calc(var(--space-lg) * 2.25)");
+    expect(floatingToggleRule).toContain("box-shadow: var(--shadow-md)");
   });
 
   it("FN-4352: response copy action stays compact on mobile", async () => {