diff --git a/src/renderer/components/thread/ThreadToolRail.tsx b/src/renderer/components/thread/ThreadToolRail.tsx
index 1523c749..62ddaf78 100644
--- a/src/renderer/components/thread/ThreadToolRail.tsx
+++ b/src/renderer/components/thread/ThreadToolRail.tsx
@@ -1,4 +1,4 @@
-import { useLayoutEffect, useRef, useState } from "react";
+import { useEffect, useLayoutEffect, useRef, useState } from "react";
 import { createPortal } from "react-dom";
 import type { LucideIcon } from "lucide-react";
 import { FileDiff, FolderOpen, NotebookPen, PanelRightOpen, TerminalSquare } from "lucide-react";
@@ -27,6 +27,7 @@ const railPillClass = "flex flex-col items-center gap-0.5 rounded-full p-1";
  * each side — 920 + 2 × 44.
  */
 const ALWAYS_OPEN_MIN_PANE_WIDTH = 1008;
+const HEADER_MENU_CLOSE_DELAY_MS = 250;
 
 interface RailTool {
   id: string;
@@ -84,14 +85,32 @@ export function ThreadToolRail(props: {
 
   const paneAnchorRef = useRef<HTMLSpanElement>(null);
   const pillRef = useRef<HTMLDivElement>(null);
+  const headerMenuCloseTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
   const [paneElement, setPaneElement] = useState<HTMLElement | null>(null);
   const [paneWidth, setPaneWidth] = useState<number | null>(null);
   const [paneHeight, setPaneHeight] = useState<number | null>(null);
   const [railHeight, setRailHeight] = useState<number | null>(null);
   const [headerMenuPhase, setHeaderMenuPhase] = useState<HeaderMenuPhase>("ready");
+  const [headerMenuPointerOpen, setHeaderMenuPointerOpen] = useState(false);
+  const [headerMenuFocusOpen, setHeaderMenuFocusOpen] = useState(false);
   const alwaysOpen =
     paneCount === 1 && paneWidth !== null && paneWidth >= ALWAYS_OPEN_MIN_PANE_WIDTH;
   const sideRailVisible = alwaysOpen && paneElement !== null && !sidePanelOpen;
+  const headerMenuOpen =
+    headerMenuPhase === "ready" && (headerMenuPointerOpen || headerMenuFocusOpen);
+
+  const cancelHeaderMenuClose = () => {
+    if (headerMenuCloseTimerRef.current === null) return;
+    clearTimeout(headerMenuCloseTimerRef.current);
+    headerMenuCloseTimerRef.current = null;
+  };
+
+  useEffect(
+    () => () => {
+      cancelHeaderMenuClose();
+    },
+    [],
+  );
 
   useLayoutEffect(() => {
     if (paneCount !== 1 || sidePanelOpen) return;
@@ -188,6 +207,9 @@ export function ThreadToolRail(props: {
   if (!primaryTool) return null;
 
   const suppressHeaderMenu = () => {
+    cancelHeaderMenuClose();
+    setHeaderMenuPointerOpen(false);
+    setHeaderMenuFocusOpen(false);
     setHeaderMenuPhase("suppressed");
   };
 
@@ -247,14 +269,38 @@ export function ThreadToolRail(props: {
         <div
           data-poracode-thread-tool-rail=""
           data-placement="header"
-          className="poracode-overlay-header__controls group/thread-tools relative shrink-0"
+          className="poracode-overlay-header__controls relative shrink-0"
           onPointerLeave={() => {
-            setHeaderMenuPhase((phase) => (phase === "suppressed" ? "awaiting-reentry" : phase));
+            if (headerMenuPhase === "suppressed") {
+              setHeaderMenuPhase("awaiting-reentry");
+              return;
+            }
+            cancelHeaderMenuClose();
+            headerMenuCloseTimerRef.current = setTimeout(() => {
+              headerMenuCloseTimerRef.current = null;
+              setHeaderMenuPointerOpen(false);
+            }, HEADER_MENU_CLOSE_DELAY_MS);
           }}
           onPointerEnter={() => {
-            setHeaderMenuPhase((phase) => (phase === "awaiting-reentry" ? "ready" : phase));
+            cancelHeaderMenuClose();
+            if (headerMenuPhase === "suppressed") return;
+            setHeaderMenuPointerOpen(true);
+            if (headerMenuPhase === "awaiting-reentry") setHeaderMenuPhase("ready");
+          }}
+          onFocusCapture={() => {
+            cancelHeaderMenuClose();
+            setHeaderMenuPhase("ready");
+            setHeaderMenuFocusOpen(true);
+          }}
+          onBlurCapture={(event) => {
+            if (
+              event.relatedTarget instanceof Node &&
+              event.currentTarget.contains(event.relatedTarget)
+            ) {
+              return;
+            }
+            setHeaderMenuFocusOpen(false);
           }}
-          onFocusCapture={() => setHeaderMenuPhase("ready")}
         >
           <button
             type="button"
@@ -271,9 +317,7 @@ export function ThreadToolRail(props: {
           <div
             data-poracode-thread-tool-menu=""
             className={`pointer-events-none invisible absolute left-1/2 top-full z-30 w-9 -translate-x-1/2 opacity-0 transition-opacity duration-150 ${
-              headerMenuPhase !== "ready"
-                ? ""
-                : "group-hover/thread-tools:pointer-events-auto group-hover/thread-tools:visible group-hover/thread-tools:opacity-100 group-focus-within/thread-tools:pointer-events-auto group-focus-within/thread-tools:visible group-focus-within/thread-tools:opacity-100"
+              headerMenuOpen ? "pointer-events-auto visible opacity-100" : ""
             }`}
           >
             <div className="pt-1">
diff --git a/src/renderer/components/thread/ThreadView.test.tsx b/src/renderer/components/thread/ThreadView.test.tsx
index c2907d5a..c72ba559 100644
--- a/src/renderer/components/thread/ThreadView.test.tsx
+++ b/src/renderer/components/thread/ThreadView.test.tsx
@@ -1641,59 +1641,77 @@ describe("ThreadView", () => {
     expect(hasAncestorWithClassFragment(terminalPane.parentElement, "max-w-[1040px]")).toBe(true);
   });
 
-  it("moves thread tools into the header when the pane cannot clear a side rail", () => {
-    renderThreadView({
-      thread: {
-        id: "thread-split-tool-menu",
-        projectId: "project-1",
-        title: "Split pane thread",
-        agentKind: "codex",
-        config: {
-          model: "gpt-5.4",
+  it("keeps header thread tools open while the pointer crosses into the menu", async () => {
+    vi.useFakeTimers();
+    try {
+      renderThreadView({
+        thread: {
+          id: "thread-split-tool-menu",
+          projectId: "project-1",
+          title: "Split pane thread",
+          agentKind: "codex",
+          config: {
+            model: "gpt-5.4",
+          },
+          status: "idle",
+          attention: "none",
+          canResumeWithConfig: true,
+          archived: false,
+          done: false,
+          starred: false,
+          createdAt: new Date().toISOString(),
+          updatedAt: new Date().toISOString(),
+        },
+        agentStatus: undefined,
+        projectLocation: {
+          kind: "windows",
+          path: "C:\\repo",
         },
-        status: "idle",
-        attention: "none",
-        canResumeWithConfig: true,
-        archived: false,
-        done: false,
-        starred: false,
-        createdAt: new Date().toISOString(),
-        updatedAt: new Date().toISOString(),
-      },
-      agentStatus: undefined,
-      projectLocation: {
-        kind: "windows",
-        path: "C:\\repo",
-      },
-      paneCount: 2,
-      onMarkDone: () => undefined,
-    });
+        paneCount: 2,
+        onMarkDone: () => undefined,
+      });
 
-    const headerTrigger = screen.getByRole("button", { name: "Show thread tools" });
-    const headerMenu = headerTrigger.closest("[data-poracode-thread-tool-rail]");
-    const toolMenu = headerMenu?.querySelector("[data-poracode-thread-tool-menu]");
-    const doneButton = screen.getByRole("button", { name: "Mark done" });
-
-    expect(headerMenu).toHaveAttribute("data-placement", "header");
-    expect(headerMenu).not.toHaveClass("invisible");
-    expect(toolMenu).toHaveClass("left-1/2", "w-9", "-translate-x-1/2");
-    expect(toolMenu).toHaveClass("transition-opacity");
-    expect(toolMenu).not.toHaveClass("grid-rows-[0fr]");
-    expect(toolMenu).toHaveClass("group-hover/thread-tools:visible");
-    expect(doneButton.nextElementSibling).toBe(headerMenu);
-    expect(hasAncestorWithClassFragment(headerMenu as HTMLElement, "@container")).toBe(true);
-    expect(headerMenu?.querySelector('[aria-label="Git"]')).not.toBeNull();
-    expect(headerMenu?.querySelector('[aria-label="Files"]')).not.toBeNull();
-    expect(headerMenu?.querySelector('[aria-label="Terminal"]')).not.toBeNull();
-    expect(headerMenu?.querySelector('[aria-label="Notes"]')).not.toBeNull();
-
-    fireEvent.click(headerTrigger);
-    expect(toolMenu).not.toHaveClass("group-hover/thread-tools:visible");
-    fireEvent.pointerLeave(headerMenu as HTMLElement);
-    expect(toolMenu).not.toHaveClass("group-hover/thread-tools:visible");
-    fireEvent.pointerEnter(headerMenu as HTMLElement);
-    expect(toolMenu).toHaveClass("group-hover/thread-tools:visible");
-    fireEvent.click(headerTrigger);
+      const headerTrigger = screen.getByRole("button", { name: "Show thread tools" });
+      const headerMenu = headerTrigger.closest("[data-poracode-thread-tool-rail]");
+      const toolMenu = headerMenu?.querySelector("[data-poracode-thread-tool-menu]");
+      const doneButton = screen.getByRole("button", { name: "Mark done" });
+
+      expect(headerMenu).toHaveAttribute("data-placement", "header");
+      expect(headerMenu).not.toHaveClass("invisible");
+      expect(toolMenu).toHaveClass("left-1/2", "w-9", "-translate-x-1/2");
+      expect(toolMenu).toHaveClass("transition-opacity");
+      expect(toolMenu).not.toHaveClass("grid-rows-[0fr]");
+      expect(toolMenu).toHaveClass("invisible");
+      expect(doneButton.nextElementSibling).toBe(headerMenu);
+      expect(hasAncestorWithClassFragment(headerMenu as HTMLElement, "@container")).toBe(true);
+      expect(headerMenu?.querySelector('[aria-label="Git"]')).not.toBeNull();
+      expect(headerMenu?.querySelector('[aria-label="Files"]')).not.toBeNull();
+      expect(headerMenu?.querySelector('[aria-label="Terminal"]')).not.toBeNull();
+      expect(headerMenu?.querySelector('[aria-label="Notes"]')).not.toBeNull();
+
+      fireEvent.pointerEnter(headerMenu as HTMLElement);
+      expect(toolMenu).toHaveClass("visible");
+
+      fireEvent.pointerLeave(headerMenu as HTMLElement);
+      expect(toolMenu).toHaveClass("visible");
+      fireEvent.pointerEnter(toolMenu as HTMLElement);
+      await act(() => vi.advanceTimersByTimeAsync(300));
+      expect(toolMenu).toHaveClass("visible");
+
+      fireEvent.pointerLeave(headerMenu as HTMLElement);
+      await act(() => vi.advanceTimersByTimeAsync(300));
+      expect(toolMenu).toHaveClass("invisible");
+
+      fireEvent.pointerEnter(headerMenu as HTMLElement);
+      fireEvent.click(headerTrigger);
+      expect(toolMenu).toHaveClass("invisible");
+      fireEvent.pointerLeave(headerMenu as HTMLElement);
+      fireEvent.pointerEnter(headerMenu as HTMLElement);
+      expect(toolMenu).toHaveClass("visible");
+      fireEvent.click(headerTrigger);
+    } finally {
+      vi.useRealTimers();
+    }
   });
 
   it("allows queued follow-ups and stop while a GUI ACP thread is running", async () => {