diff --git a/apps/web/src/components/Sidebar.tsx b/apps/web/src/components/Sidebar.tsx
index c21191d88f5b2..868aa85cec61b 100644
--- a/apps/web/src/components/Sidebar.tsx
+++ b/apps/web/src/components/Sidebar.tsx
@@ -1032,7 +1032,6 @@ export default function Sidebar({ routeReveal }: { routeReveal: SidebarRouteReve
   const projectScopeFilter = useComboboxFilter();
   const allProjectSnapshotsReady = useAllEnvironmentProjectSnapshotsReady();
   const allProjectConfigsReady = useAtomValue(environmentProjects.projectConfigsReadyAtom);
-  const headerSearchRef = useRef<HTMLDivElement | null>(null);
   // Safari may click after Ctrl+click opens settings; suppress that selection until the picker reopens.
   const suppressNextScopeChangeRef = useRef(false);
   const highlightedProjectScopeKeyRef = useRef<string | null>(null);
@@ -2990,7 +2989,6 @@ export default function Sidebar({ routeReveal }: { routeReveal: SidebarRouteReve
         fixedHeader={
           <SidebarGroup className="z-[1]">
             <SidebarThreadHeader
-              searchFieldRef={headerSearchRef}
               hasProjects={projectGroups.length > 0}
               projectScope={
                 <Combobox
@@ -3061,8 +3059,8 @@ export default function Sidebar({ routeReveal }: { routeReveal: SidebarRouteReve
                   {/* Refocusing the trigger after a pointer close shows its focus ring and opens its tooltip. */}
                   <ComboboxPopup
                     align="start"
-                    anchor={headerSearchRef}
-                    className="max-w-[min(18rem,var(--available-width))] overflow-hidden"
+                    collisionAvoidance={{ side: "flip", align: "shift" }}
+                    className="w-[min(18rem,var(--available-width))] overflow-hidden"
                     finalFocus={(closeType) => closeType === "keyboard"}
                   >
                     <ComboboxSearchInput
diff --git a/apps/web/src/components/sidebar/SidebarThreadHeader.tsx b/apps/web/src/components/sidebar/SidebarThreadHeader.tsx
index bccbd38f86a71..e400e03d27586 100644
--- a/apps/web/src/components/sidebar/SidebarThreadHeader.tsx
+++ b/apps/web/src/components/sidebar/SidebarThreadHeader.tsx
@@ -13,7 +13,6 @@ import { SidebarInput, SidebarMenuButton } from "../ui/sidebar";
 import { Tooltip, TooltipPopup, TooltipTrigger } from "../ui/tooltip";
 
 export interface SidebarThreadHeaderProps {
-  searchFieldRef?: RefObject<HTMLDivElement | null>;
   hasProjects: boolean;
   projectScope: ReactNode;
   onNewProject: () => void;
@@ -33,7 +32,6 @@ export interface SidebarThreadHeaderProps {
 }
 
 export function SidebarThreadHeader({
-  searchFieldRef,
   hasProjects,
   projectScope,
   onNewProject,
@@ -60,10 +58,7 @@ export function SidebarThreadHeader({
 
   return (
     <div className="flex items-center gap-1">
-      <div
-        ref={searchFieldRef}
-        className="flex h-8 min-w-0 flex-1 items-center gap-2 rounded-md px-2 py-1.5 text-sm font-medium text-sidebar-muted-foreground hover:bg-sidebar-row-hover hover:text-sidebar-foreground focus-within:bg-sidebar-row-hover focus-within:text-sidebar-foreground focus-within:ring-1 focus-within:ring-inset focus-within:ring-ring/70"
-      >
+      <div className="flex h-8 min-w-0 flex-1 items-center gap-2 rounded-md px-2 py-1.5 text-sm font-medium text-sidebar-muted-foreground hover:bg-sidebar-row-hover hover:text-sidebar-foreground focus-within:bg-sidebar-row-hover focus-within:text-sidebar-foreground focus-within:ring-1 focus-within:ring-inset focus-within:ring-ring/70">
         <SearchIcon className="size-4 shrink-0 text-(--sidebar-icon-color)" />
         <SidebarInput
           ref={searchInputRef}
diff --git a/apps/web/src/components/ui/combobox.tsx b/apps/web/src/components/ui/combobox.tsx
index a1db1108fa17a..739eb15b9a064 100644
--- a/apps/web/src/components/ui/combobox.tsx
+++ b/apps/web/src/components/ui/combobox.tsx
@@ -139,6 +139,7 @@ function ComboboxPopup({
   sideOffset = 4,
   alignOffset,
   align = "start",
+  collisionAvoidance,
   anchor: anchorProp,
   ...props
 }: ComboboxPrimitive.Popup.Props & {
@@ -147,6 +148,7 @@ function ComboboxPopup({
   alignOffset?: ComboboxPrimitive.Positioner.Props["alignOffset"];
   side?: ComboboxPrimitive.Positioner.Props["side"];
   anchor?: ComboboxPrimitive.Positioner.Props["anchor"];
+  collisionAvoidance?: ComboboxPrimitive.Positioner.Props["collisionAvoidance"];
 }) {
   const { chipsRef, multiple } = React.use(ComboboxContext);
   const anchor = anchorProp ?? (multiple ? chipsRef : undefined);
@@ -157,6 +159,7 @@ function ComboboxPopup({
         align={align}
         alignOffset={alignOffset}
         anchor={anchor}
+        collisionAvoidance={collisionAvoidance}
         className="z-[130] select-none"
         data-slot="combobox-positioner"
         side={side}