Keep a disabled toggle's track visible and true to its state (#2535)

A disabled toggle set its track to `bg-base`, which isn't a theme
colour. The `base` colour alias was removed long ago because it collided
with the `text-base` font-size utility, so the track rendered
transparent. As a result, every disabled toggle showed only a faint
knob:

- Plan-locked settings such as Settings › Patrol › **Container update
risk** were nearly invisible.
- In read-only sessions, a setting that was on looked the same as one
that was off.

A disabled toggle now keeps its on or off track colour and dims to 50%.
The knob relies on the track's opacity instead of dimming a second time.

Verification:
- Measured live on Settings › Patrol, in light and dark mode at 1440px
and at 390px. With the settings response set to what a free-tier backend
returns, the track background was transparent on main; it is now the off
colour (slate-200 in light mode, slate-700 in dark) at 50%.
- With an "on" value, the same disabled toggle reads as a dimmed on
switch.
- Added a toggle test and a shared-primitive guardrail. The receipt is
included.

`bg-base` is used about 80 more times elsewhere and is a no-op in each
of those places too. That is a separate sweep.

docs/release-control/v6/internal/subsystems/frontend-primitives.md

@@ -5070,6 +5070,10 @@ plus the synthetic toggle change-event runtime, and
 track/knob/container class policy, and the canonical toggle event type.
 Future toggle work should extend those owners instead of pushing synthetic
 event behavior or size/class policy back into the shell.
+A disabled toggle (a read-only session, a plan lock, a save in flight) keeps
+its on or off track colour and dims, so it still shows whether the setting is
+on; it must not swap to a separate disabled background, which hid the track
+and made a locked-on setting read as off.
 Binary on/off controls are registry-backed too. Product surfaces must compose
 `Toggle` or `TogglePrimitive` for shared track/knob styling, disabled behavior,
 label/description wiring, and synthetic checked events instead of recreating

frontend-modern/browser-verification/4aa9308843ebb8ab.json

@@ -0,0 +1,35 @@
+{
+  "version": 1,
+  "base_sha": "1dcf9418aae87f9427dbfc6bcae67dbde114bf8a",
+  "verified_at": "2026-10-05T20:47:57Z",
+  "result": "passed",
+  "changed_paths": [
+    "frontend-modern/src/components/shared/toggleModel.ts"
+  ],
+  "content_sha256": {
+    "frontend-modern/src/components/shared/toggleModel.ts": "141b8981ae6c92eb4a3f3c8d5a82ce9b8a470f675551ec5b93d2638a5330a5d6"
+  },
+  "routes": [
+    "/settings/pulse-intelligence/patrol"
+  ],
+  "viewports": [
+    {
+      "width": 1440,
+      "height": 1000
+    },
+    {
+      "width": 390,
+      "height": 1000
+    }
+  ],
+  "states": [
+    "Settings > Patrol with the Container update risk toggle disabled by its plan lock and off (the /api/settings/ai response set to what a free-tier backend returns), light and dark",
+    "Before (main): the disabled toggle's track computed to rgba(0,0,0,0), leaving only a faint half-opacity knob on the card",
+    "After: the track keeps its off colour (rgb(226,232,240) light, rgb(51,65,85) dark) at 50% opacity and reads as a dimmed off switch; enabled toggles beside it are unchanged",
+    "With the dev stack's unmasked response (on), the same disabled toggle reads as a dimmed on switch rather than an empty track",
+    "Phone at 390: same rendering"
+  ],
+  "interactions": [
+    "Compared main (reverse-applied patch) and the change with the settings response intercepted, at 1440 light and dark and 390"
+  ]
+}

frontend-modern/src/components/shared/SharedPrimitives.guardrails.test.ts

@@ -2117,6 +2117,10 @@ describe('shared primitive guardrails', () => {
     expect(toggleModelSource).toContain('getToggleTrackClass');
     expect(toggleModelSource).toContain('getToggleKnobClass');
     expect(toggleModelSource).toContain('ToggleChangeEvent');
+    // A disabled toggle keeps its on/off track and dims; bg-base names no
+    // theme colour, so a disabled track built on it rendered transparent.
+    expect(toggleModelSource).not.toMatch(/TOGGLE_DISABLED_CLASS = '[^']*bg-base/);
+    expect(toggleModelSource).toContain('checked ? TOGGLE_CHECKED_CLASS : TOGGLE_UNCHECKED_CLASS');
 
     expect(dockerRuntimeSettingsCardSource).toContain('TogglePrimitive');
     expect(dockerRuntimeSettingsCardSource).toContain('ariaLabelledBy');

frontend-modern/src/components/shared/Toggle.test.tsx

@@ -32,6 +32,23 @@ describe('Toggle', () => {
     expect(toggleModelSource).toContain('ToggleChangeEvent');
   });
 
+  it('keeps a disabled toggle on its on or off colour, dimmed', () => {
+    render(() => (
+      <>
+        <Toggle checked disabled ariaLabel="Locked on" />
+        <Toggle checked={false} disabled ariaLabel="Locked off" />
+      </>
+    ));
+
+    const lockedOn = screen.getByRole('button', { name: 'Locked on' });
+    const lockedOff = screen.getByRole('button', { name: 'Locked off' });
+    expect(lockedOn).toHaveClass('bg-blue-500', 'opacity-50', 'cursor-not-allowed');
+    expect(lockedOff).toHaveClass('bg-border', 'opacity-50', 'cursor-not-allowed');
+    // bg-base names no theme colour, so it rendered no track at all.
+    expect(lockedOn.className).not.toContain('bg-base');
+    expect(lockedOff.className).not.toContain('bg-base');
+  });
+
   it('emits the synthetic next checked state and respects preventDefault', () => {
     const onToggle = vi.fn();
     const onChange = vi.fn((event) => event.preventDefault());

frontend-modern/src/components/shared/toggleModel.ts

@@ -11,7 +11,11 @@ export interface ToggleChangeEvent {
 
 const TOGGLE_CHECKED_CLASS = 'bg-blue-500';
 const TOGGLE_UNCHECKED_CLASS = 'bg-border';
-const TOGGLE_DISABLED_CLASS = 'bg-base cursor-not-allowed opacity-50';
+// A disabled switch (read-only session, plan lock, save in flight) keeps the
+// track colour of its state and dims, so it still says whether the setting is
+// on. The old bg-base track named no theme colour and rendered transparent:
+// a disabled switch lost its track and an enabled-but-locked one read as off.
+const TOGGLE_DISABLED_CLASS = 'cursor-not-allowed opacity-50';
 const TOGGLE_KNOB_BASE_CLASS = 'bg-surface border border-border-subtle';
 const TOGGLE_CONTAINER_CLASS = 'flex items-center gap-3';
 const TOGGLE_LABEL_CLASS = 'flex flex-col text-sm text-base-content';
@@ -50,15 +54,16 @@ export function getToggleTrackClass(
 ): string {
   const config = toggleSizeConfig[size];
   return `relative inline-flex ${config.track} shrink-0 items-center rounded-full p-0.5 transition-all duration-300 ease-[cubic-bezier(0.34,1.56,0.64,1)] after:absolute after:-inset-y-2.5 after:inset-x-0 after:content-[''] focus:outline-hidden focus:ring-0 ${
-    disabled ? TOGGLE_DISABLED_CLASS : checked ? TOGGLE_CHECKED_CLASS : TOGGLE_UNCHECKED_CLASS
-  } ${className ?? ''}`.trim();
+    checked ? TOGGLE_CHECKED_CLASS : TOGGLE_UNCHECKED_CLASS
+  } ${disabled ? TOGGLE_DISABLED_CLASS : ''} ${className ?? ''}`.trim();
 }
 
-export function getToggleKnobClass(size: ToggleSize, checked: boolean, disabled: boolean): string {
+// The knob sits inside the track, so a disabled track's opacity already dims it.
+export function getToggleKnobClass(size: ToggleSize, checked: boolean, _disabled: boolean): string {
   const config = toggleSizeConfig[size];
   return `inline-block ${config.knob} rounded-full transition-transform duration-300 ease-[cubic-bezier(0.34,1.56,0.64,1)] ${TOGGLE_KNOB_BASE_CLASS} ${
     checked ? config.translateOn : 'translate-x-0'
-  } ${disabled ? 'opacity-60' : ''}`.trim();
+  }`.trim();
 }
 
 export function getToggleContainerClass(containerClass?: string): string {