fix(webapp): navigation always collapses fullscreen chat

Author: kathiekiwi

apps/webapp/app/components/dashboard-agent/chat-open-mode.test.ts

@@ -81,4 +81,12 @@ describe("useAgentPanelMode", () => {
     act(() => hook.current.revertFullscreen());
     expect(hook.current.mode).toBe("rightPanel");
   });
+
+  it("revertFullscreen always collapses to floating, even when the preference is fullscreen", () => {
+    const hook = renderAgentPanelMode("fullscreen");
+    expect(hook.current.mode).toBe("fullscreen");
+
+    act(() => hook.current.revertFullscreen());
+    expect(hook.current.mode).toBe("floating");
+  });
 });

apps/webapp/app/components/dashboard-agent/panel-layout.tsx

@@ -85,10 +85,15 @@ export function useAgentPanelMode(modePreference: DashboardAgentMode | undefined
     setMode(initialAgentMode(modePreference));
   }, [modePreference]);
 
-  // Pathname changes must drop fullscreen back to the preference, but leave any other
-  // transient mode (e.g. rightPanel) alone.
+  // Pathname changes must drop fullscreen so the new page is visible, even when the
+  // preference itself is fullscreen — the preference governs the next open, not
+  // mid-session navigation. Any other transient mode (e.g. rightPanel) is left alone.
   const revertFullscreen = useCallback(() => {
-    setMode((current) => (current !== "fullscreen" ? current : initialAgentMode(modePreference)));
+    setMode((current) => {
+      if (current !== "fullscreen") return current;
+      const next = initialAgentMode(modePreference);
+      return next === "fullscreen" ? "floating" : next;
+    });
   }, [modePreference]);
 
   return { mode, changeMode, resetToPreference, revertFullscreen };