feat(FN-2637): align usage window hide/show controls

- Remove the per-row eye toggle for already hidden usage windows so hidden rows no longer show a show/hide button
- Keep hide controls visible for active rows and preserve existing hide interactions
- Update UsageIndicator tests to assert hidden rows omit hide buttons and visible rows still render hide controls
- Drop obsolete per-row unhide test now that restoring hidden windows is handled through the provider-level show hidden flow

packages/dashboard/app/components/UsageIndicator.tsx

@@ -1,6 +1,6 @@
 import { useState, useEffect, useCallback, useRef } from "react";
 import type { CSSProperties } from "react";
-import { X, RefreshCw, Activity, TrendingUp, CheckCircle, AlertTriangle, Eye, EyeOff } from "lucide-react";
+import { X, RefreshCw, Activity, TrendingUp, CheckCircle, AlertTriangle, Eye } from "lucide-react";
 import type { ProviderUsage, UsageWindow } from "../api";
 import { useUsageData } from "../hooks/useUsageData";
 import { ProviderIcon } from "./ProviderIcon";
@@ -187,14 +187,16 @@ function UsageWindowRow({ window, viewMode, isHidden, onToggleHidden }: UsageWin
         <span className="usage-window-label">{window.label}</span>
         <div className="usage-window-header-controls">
           {!isHidden && <span className="usage-window-percentage">{headerText}</span>}
-          <button
-            className="btn-icon usage-window-hide-btn"
-            onClick={onToggleHidden}
-            aria-label={`${isHidden ? "Show" : "Hide"} ${window.label}`}
-            data-testid="usage-window-hide-btn"
-          >
-            {isHidden ? <EyeOff size={14} /> : <Eye size={14} />}
-          </button>
+          {!isHidden && (
+            <button
+              className="btn-icon usage-window-hide-btn"
+              onClick={onToggleHidden}
+              aria-label={`Hide ${window.label}`}
+              data-testid="usage-window-hide-btn"
+            >
+              <Eye size={14} />
+            </button>
+          )}
         </div>
       </div>
       <div className="usage-progress-wrapper">

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

@@ -673,6 +673,7 @@ describe("UsageIndicator", () => {
     expect(hiddenRow).toHaveClass("usage-window--hidden");
     expect(sessionLabel).not.toBeVisible();
     expect(screen.queryByText("45% used")).not.toBeInTheDocument();
+    expect(screen.queryByRole("button", { name: "Hide Session (5h)" })).not.toBeInTheDocument();
   });
 
   it("persists hidden windows to localStorage", () => {
@@ -748,6 +749,8 @@ describe("UsageIndicator", () => {
     expect(screen.queryByTestId("usage-show-hidden-btn")).not.toBeInTheDocument();
     expect(screen.getByText("Session (5h)").closest(".usage-window")).not.toHaveClass("usage-window--hidden");
     expect(screen.getByText("Weekly").closest(".usage-window")).not.toHaveClass("usage-window--hidden");
+    expect(screen.getByRole("button", { name: "Hide Session (5h)" })).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: "Hide Weekly" })).toBeInTheDocument();
   });
 
   it("does not show provider-level show hidden button when no windows are hidden", () => {
@@ -764,22 +767,6 @@ describe("UsageIndicator", () => {
     expect(screen.queryByTestId("usage-show-hidden-btn")).not.toBeInTheDocument();
   });
 
-  it("allows un-hiding a specific hidden window", () => {
-    mockUseUsageData.mockReturnValue({
-      providers: mockProviders,
-      loading: false,
-      error: null,
-      lastUpdated: new Date(),
-      refresh: mockRefresh,
-    });
-
-    render(<UsageIndicator isOpen={true} onClose={mockOnClose} projectId={TEST_PROJECT_ID} />);
-
-    fireEvent.click(screen.getByRole("button", { name: "Hide Session (5h)" }));
-    fireEvent.click(screen.getByRole("button", { name: "Show Session (5h)" }));
-
-    expect(screen.getByText("Session (5h)").closest(".usage-window")).not.toHaveClass("usage-window--hidden");
-  });
 
   // ProviderIcon integration tests
   it("renders SVG provider icons instead of emoji", () => {