fix(FN-1458): add safe-area-inset padding to mobile header floating search

- Add safe-area-inset padding to mobile header-floating-search to prevent viewport overlap
- Add regression tests in Header.test.tsx for mobile search safe-area handling
- Add regression tests in mobile-header-controls.test.tsx for viewport safety
- Document the fix in .fusion/memory.md

packages/dashboard/app/__tests__/mobile-header-controls.test.ts

@@ -126,4 +126,23 @@ describe("mobile-header-controls.css", () => {
     // The selector should have width: 100% rule
     expect(mobileCss).toMatch(/\.mobile-search-expanded\s*\{[^}]*width:\s*100%/);
   });
+
+  it("does not contain fixed-offset patterns that can push mobile search off-screen", () => {
+    // Extract all mobile .mobile-search-expanded rules and check they don't have
+    // position: absolute with negative left/right offsets
+    const expandedBlocks = mobileCss.match(/\.mobile-search-expanded\s*\{[^}]*\}/g) || [];
+    for (const block of expandedBlocks) {
+      // Fail if any fixed negative offset is found (these push the element off-screen)
+      expect(block).not.toMatch(/left:\s*-\d/);
+      expect(block).not.toMatch(/right:\s*-\d/);
+    }
+  });
+
+  it("has mobile header-floating-search with safe-area-inset padding", () => {
+    // The header-floating-search in mobile must respect safe-area-inset
+    // to prevent clipping on notched devices
+    expect(mobileCss).toContain(".header-floating-search");
+    // Should have safe-area-inset handling for left/right
+    expect(mobileCss).toMatch(/\.header-floating-search\s*\{[^}]*env\(safe-area-inset/);
+  });
 });

packages/dashboard/app/components/Header.test.tsx

@@ -902,6 +902,31 @@ describe("Header", () => {
     });
   });
 
+  describe("mobile search with mobileNavEnabled", () => {
+    it("renders mobile search input when searchQuery is active with mobileNavEnabled", () => {
+      renderHeader({ view: "board", searchQuery: "test query", onSearchChange: vi.fn(), onChangeView: noop }, "mobile");
+      // Search should be visible even with mobileNavEnabled when query is active
+      expect(screen.getByPlaceholderText("Search tasks...")).toBeDefined();
+      expect(screen.getByDisplayValue("test query")).toBeDefined();
+    });
+
+    it("can open mobile search when mobileNavEnabled is true", () => {
+      renderHeader({ view: "board", searchQuery: "", onSearchChange: vi.fn(), onChangeView: noop }, "mobile");
+      // Should show the trigger button
+      expect(screen.getByTestId("mobile-header-search-btn")).toBeDefined();
+      // Expanded search should not be visible initially
+      expect(screen.queryByPlaceholderText("Search tasks...")).toBeNull();
+    });
+
+    it("closes mobile search and clears query when close button clicked with mobileNavEnabled", () => {
+      const onSearchChange = vi.fn();
+      renderHeader({ view: "board", searchQuery: "test query", onSearchChange, onChangeView: noop }, "mobile");
+      const closeBtn = screen.getByLabelText("Close search");
+      fireEvent.click(closeBtn);
+      expect(onSearchChange).toHaveBeenCalledWith("");
+    });
+  });
+
   describe("Projects button", () => {
     const singleProject = [
       { id: "1", name: "Test Project", path: "/path/to/project", status: "active" as const },

packages/dashboard/app/components/__tests__/Header.test.tsx

@@ -946,6 +946,57 @@ describe("Header", () => {
       fireEvent.click(screen.getByTestId("overflow-scripts-manage"));
       expect(onOpenScripts).toHaveBeenCalledOnce();
     });
+
+    // ── Mobile Search with mobileNavEnabled ───────────────────────
+
+    it("renders mobile search input when searchQuery is active with mobileNavEnabled", () => {
+      const onSearchChange = vi.fn();
+      render(
+        <Header
+          view="board"
+          onChangeView={vi.fn()}
+          searchQuery="test query"
+          onSearchChange={onSearchChange}
+          mobileNavEnabled={true}
+        />
+      );
+      // Search should be visible even with mobileNavEnabled when query is active
+      expect(screen.getByPlaceholderText("Search tasks...")).toBeDefined();
+      expect(screen.getByDisplayValue("test query")).toBeDefined();
+    });
+
+    it("can open mobile search when mobileNavEnabled is true", () => {
+      const onSearchChange = vi.fn();
+      render(
+        <Header
+          view="board"
+          onChangeView={vi.fn()}
+          searchQuery=""
+          onSearchChange={onSearchChange}
+          mobileNavEnabled={true}
+        />
+      );
+      // Should show the trigger button
+      expect(screen.getByTestId("mobile-header-search-btn")).toBeDefined();
+      // Expanded search should not be visible initially
+      expect(screen.queryByPlaceholderText("Search tasks...")).toBeNull();
+    });
+
+    it("closes mobile search and clears query when close button clicked with mobileNavEnabled", () => {
+      const onSearchChange = vi.fn();
+      render(
+        <Header
+          view="board"
+          onChangeView={vi.fn()}
+          searchQuery="test query"
+          onSearchChange={onSearchChange}
+          mobileNavEnabled={true}
+        />
+      );
+      const closeBtn = screen.getByLabelText("Close search");
+      fireEvent.click(closeBtn);
+      expect(onSearchChange).toHaveBeenCalledWith("");
+    });
   });
 
   // ── Multi-Project Selector ────────────────────────────────────

packages/dashboard/app/styles.css

@@ -6403,6 +6403,12 @@ body {
     width: 100%;
   }
 
+  /* Mobile: floating search must respect safe-area-inset to stay on-screen */
+  .header-floating-search {
+    padding-left: max(var(--space-md), env(safe-area-inset-left, 0px));
+    padding-right: max(var(--space-md), env(safe-area-inset-right, 0px));
+  }
+
   /* Modal: full-screen on mobile */
   .modal-overlay {
     padding-top: 0;