diff --git a/src/panelStackLayout.test.mjs b/src/panelStackLayout.test.mjs
index a13f5c04b..ecccd21a1 100644
--- a/src/panelStackLayout.test.mjs
+++ b/src/panelStackLayout.test.mjs
@@ -188,7 +188,7 @@ test('desktop panel lanes use per-panel allocations and presentation-only auto-c
     'focus mode must hide every collapsed sibling, including presentation-only auto-collapses',
   );
   assert.doesNotMatch(css, /layout-focus > \[data-panel-id\]\.collapsed:not\(\.layout-auto-collapsed\)/);
-  assert.match(leftRail, /const hiddenSibling =\s*shouldFocus && panel\.classList\.contains\('collapsed'\);/);
+  assert.match(leftRail, /if \(exclusive && panel\.classList\.contains\('collapsed'\)\)\s*panel\.setAttribute\('aria-hidden', 'true'\)/);
 });
 
 test('share-panel state excludes responsive collapse and preserves recipient preferences', () => {
@@ -198,7 +198,7 @@ test('share-panel state excludes responsive collapse and preserves recipient pre
 
   assert.match(
     ui,
-    /const collapsed =[\s\S]*?panelEl\.classList\.contains\('layout-auto-collapsed'\)[\s\S]*?panelEl\.classList\.contains\('cyber-accordion-collapsed'\)[\s\S]*?\? false\s*: panelEl\.classList\.contains\('collapsed'\);/,
+    /const collapsed =[\s\S]*?panelEl\.classList\.contains\('layout-auto-collapsed'\)[\s\S]*?panelEl\.classList\.contains\('accordion-collapsed'\)[\s\S]*?\? false\s*: panelEl\.classList\.contains\('collapsed'\);/,
     'responsive auto-collapse must serialize the explicit expanded preference',
   );
   assert.match(
diff --git a/src/rightRailPolicy.js b/src/rightRailPolicy.js
index 02d7972c4..08eab4fb0 100644
--- a/src/rightRailPolicy.js
+++ b/src/rightRailPolicy.js
@@ -1,5 +1,3 @@
-export { shouldHideCollapsedRightPanels } from './ui/panelRailGeometry.js';
-
 const GLOBAL_CONTEXT_EXPLICIT_ACTIONS = new Set([
   'contacts',
   'space-missions',
diff --git a/src/rightRailPolicy.test.mjs b/src/rightRailPolicy.test.mjs
index 2254ea24e..dde4c64be 100644
--- a/src/rightRailPolicy.test.mjs
+++ b/src/rightRailPolicy.test.mjs
@@ -2,50 +2,20 @@ import { readStylesheet } from './testSupport/readStylesheet.mjs';
 import assert from 'node:assert/strict';
 import { readFileSync } from 'node:fs';
 import test from 'node:test';
-import {
-  shouldExpandGlobalContextPanel,
-  shouldHideCollapsedRightPanels,
-} from './rightRailPolicy.js';
+import { shouldExpandGlobalContextPanel } from './rightRailPolicy.js';
 
-test('Tactical HUD hides collapsed right-rail siblings while one panel is expanded', () => {
-  assert.equal(shouldHideCollapsedRightPanels({
-    hudVariant: 'tactical',
-    hasExpandedPanel: true,
-  }), true);
-});
-
-test('collapsed launchers remain when Tactical has no expanded panel', () => {
-  assert.equal(shouldHideCollapsedRightPanels({
-    hudVariant: 'tactical',
-    hasExpandedPanel: false,
-  }), false);
-});
-
-test('other HUD layouts keep collapsed right-rail launchers visible', () => {
-  assert.equal(shouldHideCollapsedRightPanels({
-    hudVariant: 'minimal',
-    hasExpandedPanel: true,
-  }), false);
-  assert.equal(shouldHideCollapsedRightPanels({
-    hudVariant: 'full',
-    hasExpandedPanel: true,
-  }), false);
-});
-
-test('desktop Display participates in Tactical exclusivity without changing mobile Display behavior', () => {
-  const ui = readFileSync(new URL('./ui/rightPanelRail.js', import.meta.url), 'utf8');
+test('desktop side rails hide collapsed panels in every HUD layout, never on phones', () => {
+  const right = readFileSync(new URL('./ui/rightPanelRail.js', import.meta.url), 'utf8');
+  const left = readFileSync(new URL('./ui/leftPanelRail.js', import.meta.url), 'utf8');
   const css = readStylesheet(new URL('../style.css', import.meta.url));
-  assert.match(ui, /const isMobile = windowRef\.matchMedia\('\(max-width: 720px\)'\)\.matches/);
-  assert.match(
-    ui,
-    /!panel\.classList\.contains\('collapsed'\)\s*&&\s*\(!isMobile \|\| panel\.id !== 'pp-toggles'\)/,
-  );
-  assert.doesNotMatch(
-    ui,
-    /panel\.id !== 'pp-toggles' && !panel\.classList\.contains\('collapsed'\)/,
-  );
-  assert.match(ui, /if \(exclusive && panel\.classList\.contains\('collapsed'\)\)\s*panel\.setAttribute\('aria-hidden', 'true'\)/);
+  for (const ui of [right, left]) {
+    assert.match(ui, /const isMobile = windowRef\.matchMedia\('\(max-width: 720px\)'\)\.matches/);
+    assert.match(ui, /const exclusive = !isMobile;/);
+    assert.match(ui, /if \(exclusive && panel\.classList\.contains\('collapsed'\)\)\s*panel\.setAttribute\('aria-hidden', 'true'\)/);
+    assert.doesNotMatch(ui, /hud\.variant === 'cyber'/);
+  }
   assert.match(css, /#right-context-rail\.layout-exclusive > \[data-panel-id\]\.collapsed \{/);
+  assert.match(css, /#left-panel-stack\.layout-exclusive > \[data-panel-id\]\.collapsed \{/);
 });
 
 test('explicit Contacts, Space Missions, and Cockpit actions expand Global Context after success', () => {
diff --git a/src/ui/leftPanelRail.js b/src/ui/leftPanelRail.js
index 607e13083..a0de82746 100644
--- a/src/ui/leftPanelRail.js
+++ b/src/ui/leftPanelRail.js
@@ -21,6 +21,7 @@ import { measurePanelNaturalHeight } from './panelMeasurement.js';
  * @param {Function} [options.getComputedStyle] Optional DOM style reader override.
  * @param {Map<string, number>} options.collapsedHeights Caller-owned measurement cache.
  * @param {Function} options.onAligned Notify the caller after the left rail moves.
+ * @param {Document} [options.documentRef] Document supplying current keyboard focus.
  */
 export function layoutLeftPanelRail({
   stack,
@@ -32,6 +33,7 @@ export function layoutLeftPanelRail({
   onRetry,
   collapsedHeights,
   onAligned,
+  documentRef = stack?.ownerDocument,
   getComputedStyle = (element) => windowRef.getComputedStyle(element),
 }) {
   if (!stack) return;
@@ -49,20 +51,49 @@ export function layoutLeftPanelRail({
 
   // The existing narrow-screen composition has its own full-width stack.
   // Keep this desktop lane engine from fighting those dedicated rules.
-  if (windowRef.matchMedia('(max-width: 720px)').matches) {
+  const isMobile = windowRef.matchMedia('(max-width: 720px)').matches;
+  if (isMobile) {
     stack.classList.remove('layout-focus');
     stack.classList.remove('layout-tail');
     stack.style.removeProperty('--left-stack-safe-top');
     stack.style.removeProperty('--left-stack-safe-bottom');
     stack.style.removeProperty('--left-stack-centered-height');
+    stack.classList.remove('layout-exclusive');
     stack.dataset.layoutMode = 'mobile';
     for (const panel of panels) {
+      if (panel.classList.contains('accordion-collapsed')) {
+        panel.classList.remove('collapsed', 'accordion-collapsed');
+        onCollapse(panel);
+      }
       panel.removeAttribute('aria-hidden');
       panel.style.removeProperty('--left-panel-allocated-height');
     }
     return;
   }
 
+  // One panel is open per desktop side and the panel rail lists the others,
+  // so collapsed panels are hidden. Normalize restored state without
+  // overwriting saved panel preferences.
+  const expandedBeforeAccordion = panels.filter(
+    (panel) => !panel.classList.contains('collapsed'),
+  );
+  const accordionOwner =
+    expandedBeforeAccordion.find((panel) => panel.id === preferredPanelId) ||
+    expandedBeforeAccordion.find((panel) =>
+      panel.contains(documentRef?.activeElement),
+    ) ||
+    expandedBeforeAccordion[0];
+  for (const panel of expandedBeforeAccordion) {
+    if (panel === accordionOwner) continue;
+    panel.classList.add('collapsed', 'accordion-collapsed');
+    onCollapse(panel);
+  }
+  const exclusive = !isMobile;
+  stack.classList.toggle('layout-exclusive', exclusive);
+  const laidOutPanels = panels.filter(
+    (panel) => !exclusive || !panel.classList.contains('collapsed'),
+  );
+
   const viewportHeight = Math.max(1, windowRef.innerHeight);
   const stackRect = stack.getBoundingClientRect();
   const baseTop = viewportHeight * 0.26;
@@ -162,7 +193,7 @@ export function layoutLeftPanelRail({
     (sum, height) => sum + height,
     0,
   );
-  const siblingHeight = panels.reduce((total, panel) => {
+  const siblingHeight = laidOutPanels.reduce((total, panel) => {
     if (!panel.classList.contains('collapsed')) return total;
     const measured = collapsedHeights.get(panel.id);
     return total + (measured || panel.getBoundingClientRect().height || 0);
@@ -170,12 +201,8 @@ export function layoutLeftPanelRail({
   let requiredHeight = siblingHeight;
 
   const rowGap = parseFloat(getComputedStyle(stack).rowGap) || 0;
-  if (expandedPanels.length) {
-    requiredHeight += naturalExpandedHeight;
-    requiredHeight += rowGap * Math.max(0, panels.length - 1);
-  } else {
-    requiredHeight += rowGap * Math.max(0, panels.length - 1);
-  }
+  if (expandedPanels.length) requiredHeight += naturalExpandedHeight;
+  requiredHeight += rowGap * Math.max(0, laidOutPanels.length - 1);
 
   const wasFocused = stack.classList.contains('layout-focus');
   const wasTail = stack.classList.contains('layout-tail');
@@ -189,7 +216,7 @@ export function layoutLeftPanelRail({
   const tailRequiredHeight =
     naturalExpandedHeight +
     siblingHeight +
-    rowGap * Math.max(0, panels.length - 1);
+    rowGap * Math.max(0, laidOutPanels.length - 1);
   // A compact expansion should not make the whole control stack jump down
   // merely to center a few short rows. Preserve the normal top anchor when
   // the centered stack would begin below it; tall stacks can still grow
@@ -296,8 +323,8 @@ export function layoutLeftPanelRail({
   // CockpitView.syncSignalLayout() owns `--cockpit-utility-top` instead.
 
   for (const panel of panels) {
-    const hiddenSibling = shouldFocus && panel.classList.contains('collapsed');
-    if (hiddenSibling) panel.setAttribute('aria-hidden', 'true');
+    if (exclusive && panel.classList.contains('collapsed'))
+      panel.setAttribute('aria-hidden', 'true');
     else panel.removeAttribute('aria-hidden');
   }
   // The right controls share this top baseline; update them after the left
diff --git a/src/ui/mobileShell.js b/src/ui/mobileShell.js
index 2363fd9ed..07c21a46b 100644
--- a/src/ui/mobileShell.js
+++ b/src/ui/mobileShell.js
@@ -208,7 +208,7 @@ export function initMobileShell({
     return (
       classes.contains('collapsed') &&
       !classes.contains('layout-auto-collapsed') &&
-      !classes.contains('cyber-accordion-collapsed')
+      !classes.contains('accordion-collapsed')
     );
   };
 
diff --git a/src/ui/panelChrome.js b/src/ui/panelChrome.js
index bcf730f60..459694967 100644
--- a/src/ui/panelChrome.js
+++ b/src/ui/panelChrome.js
@@ -362,7 +362,7 @@ export class PanelChrome {
       // restore the user's explicit expanded preference at its own viewport.
       const collapsed =
         panelEl.classList.contains('layout-auto-collapsed') ||
-        panelEl.classList.contains('cyber-accordion-collapsed')
+        panelEl.classList.contains('accordion-collapsed')
           ? false
           : panelEl.classList.contains('collapsed');
       // A panel the phone shell only borrowed for a sheet shares its own state.
@@ -420,19 +420,22 @@ export class PanelChrome {
     const nextCollapsed = Boolean(collapsed);
     const wasAutoCollapsed =
       panelEl.classList.contains('layout-auto-collapsed') ||
-      panelEl.classList.contains('cyber-accordion-collapsed');
-    // A user opening a Cyber rail panel owns the whole accordion, including
-    // peers that were only presentation-collapsed during a saved-state restore.
+      panelEl.classList.contains('accordion-collapsed');
+    // One panel is open per desktop side: a user opening a side panel owns
+    // the whole accordion, including peers that were only
+    // presentation-collapsed during a saved-state restore.
+    const sideStack = [this._leftPanelStack, this._rightPanelStack].find(
+      (stack) => stack && panelEl.parentElement === stack,
+    );
     if (
       explicit &&
       !restore &&
       !nextCollapsed &&
-      document.documentElement?.dataset.uiTheme === 'cyber' &&
-      panelEl.parentElement === this._rightPanelStack &&
+      sideStack &&
       // Phone sheets show several rail panels at once.
       !document.body?.classList?.contains('mobile-shell')
     ) {
-      for (const peer of this._rightPanelStack.children) {
+      for (const peer of sideStack.children) {
         if (
           peer !== panelEl &&
           peer.matches('[data-panel-id]') &&
@@ -480,7 +483,6 @@ export class PanelChrome {
     // Reveal Radio's owner before the no-op check: the nested section may
     // already be expanded while its Context parent is closed.
     if (
-      document.documentElement?.dataset.uiTheme === 'cyber' &&
       !nextCollapsed &&
       panelId === 'radio-panel' &&
       document
@@ -507,10 +509,7 @@ export class PanelChrome {
       }
       return;
     }
-    panelEl.classList.remove(
-      'layout-auto-collapsed',
-      'cyber-accordion-collapsed',
-    );
+    panelEl.classList.remove('layout-auto-collapsed', 'accordion-collapsed');
     if (
       !nextCollapsed &&
       this.cockpitView?.active &&
@@ -522,20 +521,6 @@ export class PanelChrome {
         this.cockpitView.setContextCollapsed(true);
       }
     }
-    if (
-      !nextCollapsed &&
-      panelId === 'radio-panel' &&
-      document.documentElement?.dataset.uiTheme !== 'cyber' &&
-      document
-        .getElementById('global-context-panel')
-        ?.classList.contains('collapsed')
-    ) {
-      this.setPanelCollapsed('global-context-panel', false, {
-        restore,
-        persist,
-        syncShare,
-      });
-    }
     if (!nextCollapsed && !restore && panelId === 'location-bar') {
       const otherPanel = document.getElementById('control-panel');
       if (otherPanel && !otherPanel.classList.contains('dock-pinned')) {
diff --git a/src/ui/panelRailGeometry.js b/src/ui/panelRailGeometry.js
index 8045286b0..b5a129c21 100644
--- a/src/ui/panelRailGeometry.js
+++ b/src/ui/panelRailGeometry.js
@@ -60,19 +60,3 @@ export function resolveHudRailLayout({
     constrained: panelHeight > availableHeight,
   };
 }
-
-/**
- * Tactical HUD gives an expanded right-rail panel the whole control lane.
- * Other HUD layouts keep collapsed launchers visible for quick switching.
- *
- * @param {object} input Current rail state.
- * @param {string} input.hudVariant Active HUD layout variant.
- * @param {boolean} input.hasExpandedPanel Whether any rail panel is expanded.
- * @returns {boolean} Whether collapsed sibling launchers should be hidden.
- */
-export function shouldHideCollapsedRightPanels({
-  hudVariant,
-  hasExpandedPanel,
-}) {
-  return hudVariant === 'tactical' && Boolean(hasExpandedPanel);
-}
diff --git a/src/ui/panelRails.js b/src/ui/panelRails.js
index a67371cc7..e447d6302 100644
--- a/src/ui/panelRails.js
+++ b/src/ui/panelRails.js
@@ -1,10 +1,7 @@
 export { layoutLeftPanelRail } from './leftPanelRail.js';
 export { layoutRightPanelRail } from './rightPanelRail.js';
 export { measurePanelNaturalHeight } from './panelMeasurement.js';
-export {
-  resolveHudRailLayout,
-  shouldHideCollapsedRightPanels,
-} from './panelRailGeometry.js';
+export { resolveHudRailLayout } from './panelRailGeometry.js';
 export {
   allocatePanelStackHeights,
   panelStackAutoCollapseIndices,
diff --git a/src/ui/panelRails.test.mjs b/src/ui/panelRails.test.mjs
index 546cad87b..e7f0d07cf 100644
--- a/src/ui/panelRails.test.mjs
+++ b/src/ui/panelRails.test.mjs
@@ -20,61 +20,57 @@ test('Display uses an inner scroll body only in Cyber', () => {
   assert.equal(displayPanelScroller(null), null);
 });
 
-test('Cyber restores one expanded owner, keeps launchers, and restores other theme preferences', () => {
-  for (const mobile of [false]) {
-    const f = fixture('right', {
-      mobile,
-      hud: { visible: true, variant: 'cyber' },
-    });
+for (const side of ['left', 'right']) {
+  test(`${side} desktop rail keeps one expanded owner in every HUD layout`, () => {
+    for (const variant of ['tactical', 'minimal', 'cyber']) {
+      const f = fixture(side, { hud: { visible: true, variant } });
+      f.expand(f.first, 250);
+      f.expand(f.second, 250);
+      f.options.preferredPanelId = f.second.id;
+      f.run();
+      assert.equal(f.first.classList.contains('accordion-collapsed'), true);
+      assert.equal(f.second.classList.contains('collapsed'), false);
+      assert.equal(f.stack.classList.contains('layout-exclusive'), true);
+      assert.equal(f.first.getAttribute('aria-hidden'), 'true');
+      assert.equal(f.retries(), 0, 'the accordion needs no auto-collapse pass');
+      f.run();
+      assert.equal(
+        f.first.classList.contains('collapsed'),
+        true,
+        'layout does not reopen a peer',
+      );
+      // Phone sheets restore the presentation-only collapse.
+      f.options.windowRef.matchMedia = () => ({ matches: true });
+      f.run();
+      assert.equal(f.first.classList.contains('collapsed'), false);
+      assert.equal(f.first.classList.contains('accordion-collapsed'), false);
+      assert.equal(f.stack.classList.contains('layout-exclusive'), false);
+    }
+  });
+
+  test(`${side} rail keeps no accordion on phones, where it is presented as tab sheets`, () => {
+    // A sheet (for example Cameras: CCTV with Street Level) shows several of the
+    // rail's panels at once; the accordion would collapse all but one.
+    const f = fixture(side, { mobile: true });
     f.expand(f.first, 250);
     f.expand(f.second, 250);
     f.options.preferredPanelId = f.second.id;
     f.run();
-    assert.equal(f.first.classList.contains('cyber-accordion-collapsed'), true);
-    assert.equal(f.second.classList.contains('collapsed'), false);
-    assert.equal(f.first.getAttribute('aria-hidden'), undefined);
-    f.run();
-    assert.equal(
-      f.first.classList.contains('collapsed'),
-      true,
-      'layout does not reopen a peer',
-    );
-    f.options.hud.variant = 'minimal';
-    f.run();
     assert.equal(f.first.classList.contains('collapsed'), false);
-    assert.equal(
-      f.first.classList.contains('cyber-accordion-collapsed'),
-      false,
-    );
+    assert.equal(f.first.classList.contains('accordion-collapsed'), false);
     assert.equal(f.second.classList.contains('collapsed'), false);
-  }
-});
-
-test('Cyber keeps no accordion on phones, where the rail is presented as tab sheets', () => {
-  // A sheet (for example Cameras: CCTV with Street Level) shows several of the
-  // rail's panels at once; the accordion would collapse all but one.
-  const f = fixture('right', {
-    mobile: true,
-    hud: { visible: true, variant: 'cyber' },
   });
-  f.expand(f.first, 250);
-  f.expand(f.second, 250);
-  f.options.preferredPanelId = f.second.id;
-  f.run();
-  assert.equal(f.first.classList.contains('collapsed'), false);
-  assert.equal(f.first.classList.contains('cyber-accordion-collapsed'), false);
-  assert.equal(f.second.classList.contains('collapsed'), false);
-});
 
-test('Cyber restored accordion prefers keyboard focus when no explicit owner exists', () => {
-  const f = fixture('right', { hud: { visible: true, variant: 'cyber' } });
-  f.expand(f.first, 250);
-  f.expand(f.second, 250);
-  f.options.documentRef.activeElement = f.second;
-  f.run();
-  assert.equal(f.first.classList.contains('collapsed'), true);
-  assert.equal(f.second.classList.contains('collapsed'), false);
-});
+  test(`${side} restored accordion prefers keyboard focus when no explicit owner exists`, () => {
+    const f = fixture(side);
+    f.expand(f.first, 250);
+    f.expand(f.second, 250);
+    f.options.documentRef.activeElement = f.second;
+    f.run();
+    assert.equal(f.first.classList.contains('collapsed'), true);
+    assert.equal(f.second.classList.contains('collapsed'), false);
+  });
+}
 
 function element(
   id,
@@ -250,16 +246,16 @@ for (const side of ['left', 'right']) {
     );
     assert.equal(f.first.getAttribute('aria-hidden'), undefined);
   });
-  test(`${side} constrained layout preserves the preferred panel and requests another pass`, () => {
+  test(`${side} constrained layout keeps the preferred panel without another pass`, () => {
     const f = fixture(side);
     f.expand(f.first, 900);
     f.expand(f.second, 900);
     f.options.preferredPanelId = 'second';
     f.run();
     assert.equal(f.second.classList.contains('collapsed'), false);
-    assert.equal(f.first.classList.contains('layout-auto-collapsed'), true);
+    assert.equal(f.first.classList.contains('accordion-collapsed'), true);
     assert.deepEqual(f.collapsed, ['first']);
-    assert.equal(f.retries(), 1);
+    assert.equal(f.retries(), 0);
   });
   test(`${side} hidden HUD restores automatic collapse without altering manual collapse`, () => {
     const f = fixture(side, { hud: { visible: false, variant: 'tactical' } });
@@ -277,7 +273,7 @@ test('right layout uses keyboard focus when there is no preferred panel', () =>
   f.expand(f.second, 900);
   f.options.documentRef.activeElement = f.second;
   f.run();
-  assert.equal(f.first.classList.contains('layout-auto-collapsed'), true);
+  assert.equal(f.first.classList.contains('accordion-collapsed'), true);
   assert.equal(f.second.classList.contains('collapsed'), false);
 });
 
@@ -532,26 +528,27 @@ test('right rail enters focus only above available height and leaves below the f
   assert.equal(f.stack.classList.contains('layout-focus'), false);
 });
 
-test('right rail auto-collapse requests only one retry and settles within two passes', () => {
+test('right rail settles a second tall panel through the accordion in one pass', () => {
   const f = thrashingRightRail({ weatherOpen: true });
   const modes = [];
   for (let pass = 0; pass < 10; pass++) {
     f.run();
-    modes.push(f.stack.classList.contains('layout-focus'));
+    modes.push(f.stack.dataset.layoutMode);
   }
   assert.deepEqual(f.collapsed, ['weather-panel']);
-  assert.equal(f.retries(), 1);
-  assert.deepEqual(modes.slice(1), Array(9).fill(true));
+  assert.equal(f.weather.classList.contains('accordion-collapsed'), true);
+  assert.equal(f.retries(), 0);
+  assert.deepEqual(modes.slice(1), Array(9).fill(modes[0]));
 });
 
-test('right rail retry cannot enqueue another retry even if disclosure changes before it runs', () => {
+test('right rail reopening a peer outside the rail keeps one owner without retrying', () => {
   const f = thrashingRightRail({ weatherOpen: true });
   f.run();
-  assert.equal(f.retries(), 1);
-  f.weather.classList.remove('collapsed', 'layout-auto-collapsed');
+  f.weather.classList.remove('collapsed', 'accordion-collapsed');
   f.run();
-  assert.equal(f.retries(), 1);
-  assert.equal(f.stack.dataset.layoutMode, 'focus');
+  assert.equal(f.retries(), 0);
+  assert.equal(f.weather.classList.contains('collapsed'), true);
+  assert.equal(f.cctv.classList.contains('collapsed'), false);
 });
 
 test('right rail restores presentation even when intrinsic measurement throws', () => {
@@ -595,14 +592,14 @@ test('right rail measuring pass keeps an opted-in scroller position', () => {
 });
 
 for (const variant of ['minimal', 'full']) {
-  test(`right rail does not retry collapse that the ${variant} HUD immediately restores`, () => {
+  test(`right rail settles two tall panels without retrying in the ${variant} HUD`, () => {
     const f = fixture('right', { hud: { visible: true, variant } });
     f.expand(f.first, 900);
     f.expand(f.second, 900);
     for (let pass = 0; pass < 10; pass++) f.run();
     assert.equal(f.retries(), 0);
     assert.equal(f.first.classList.contains('collapsed'), false);
-    assert.equal(f.second.classList.contains('collapsed'), false);
+    assert.equal(f.second.classList.contains('accordion-collapsed'), true);
   });
 }
 // ── Narrow-screen rail overflow pin ──────────────────────────────────────────
@@ -699,10 +696,11 @@ test('right layout ignores a CSS-hidden expanded panel when deciding exclusivity
 
   f.run();
 
-  assert.equal(f.stack.classList.contains('layout-exclusive'), false);
+  // The rail lists the collapsed panels; the CSS-hidden one claims nothing.
+  assert.equal(f.stack.classList.contains('layout-exclusive'), true);
   assert.equal(f.stack.dataset.expandedCount, '0');
-  assert.equal(f.first.getAttribute('aria-hidden'), undefined);
-  assert.equal(f.second.getAttribute('aria-hidden'), undefined);
+  assert.equal(weather.classList.contains('collapsed'), false);
+  assert.equal(weather.getAttribute('aria-hidden'), undefined);
   assert.equal(
     weather.style.getPropertyValue('--right-panel-allocated-height'),
     '',
@@ -730,9 +728,10 @@ test('right layout still restores panels that exclusive presentation hides', ()
 
   f.options.hud.visible = false;
   f.run();
-  assert.equal(f.second.classList.contains('collapsed'), false);
+  // Restored from the space-based collapse, it yields to the accordion owner.
   assert.equal(f.second.classList.contains('layout-auto-collapsed'), false);
-  assert.deepEqual(f.collapsed, ['second']);
+  assert.equal(f.second.classList.contains('accordion-collapsed'), true);
+  assert.equal(f.first.classList.contains('collapsed'), false);
 });
 
 test('right layout ignores a hidden panel: no lane, no gap, no auto-collapse', () => {
@@ -766,10 +765,10 @@ test('right layout ignores a hidden panel: no lane, no gap, no auto-collapse', (
   const retriesBefore = f.retries();
   f.run();
   assert.ok(
-    f.collapsed.includes('recent-imagery-panel'),
-    'focus mode collapses the later panel and asks for another pass',
+    imagery.classList.contains('accordion-collapsed'),
+    'the accordion keeps the first panel and collapses the later one',
   );
-  assert.equal(f.retries(), retriesBefore + 1);
+  assert.equal(f.retries(), retriesBefore);
   f.run();
   assert.equal(f.stack.dataset.expandedCount, '1');
   assert.ok(
diff --git a/src/ui/rightPanelRail.js b/src/ui/rightPanelRail.js
index 5d3e5e40c..5afdce2b7 100644
--- a/src/ui/rightPanelRail.js
+++ b/src/ui/rightPanelRail.js
@@ -2,10 +2,7 @@ import {
   allocatePanelStackHeights,
   panelStackAutoCollapseIndices,
 } from '../panelStackLayout.js';
-import {
-  resolveHudRailLayout,
-  shouldHideCollapsedRightPanels,
-} from './panelRailGeometry.js';
+import { resolveHudRailLayout } from './panelRailGeometry.js';
 
 import { displayPanelScroller } from './displayPanelScroll.js';
 
@@ -89,11 +86,12 @@ export function layoutRightPanelRail({
       onCollapse(panel);
     }
   }
-  // Normalize restored state and theme entry without overwriting saved panel
-  // preferences. This marker is distinct from Tactical's space-based collapse.
-  // Phones present the rail as tab sheets that show several panels at once.
+  // One panel is open per desktop side. Normalize restored state without
+  // overwriting saved panel preferences; this marker is distinct from
+  // Tactical's space-based collapse. Phones present the rail as tab sheets
+  // that show several panels at once.
   const isMobile = windowRef.matchMedia('(max-width: 720px)').matches;
-  if (hud.variant === 'cyber' && !isMobile) {
+  if (!isMobile) {
     const expanded = panels.filter(
       (panel) => !panel.classList.contains('collapsed'),
     );
@@ -103,29 +101,20 @@ export function layoutRightPanelRail({
       expanded[0];
     for (const panel of expanded) {
       if (panel === owner) continue;
-      panel.classList.add('collapsed', 'cyber-accordion-collapsed');
+      panel.classList.add('collapsed', 'accordion-collapsed');
       onCollapse(panel);
     }
   } else {
     for (const panel of panels) {
-      if (!panel.classList.contains('cyber-accordion-collapsed')) continue;
-      panel.classList.remove('collapsed', 'cyber-accordion-collapsed');
+      if (!panel.classList.contains('accordion-collapsed')) continue;
+      panel.classList.remove('collapsed', 'accordion-collapsed');
       onCollapse(panel);
     }
   }
-  const hasExpandedPanel = panels.some(
-    (panel) =>
-      !panel.classList.contains('collapsed') &&
-      (!isMobile || panel.id !== 'pp-toggles'),
-  );
+  // The desktop panel rail lists every panel, so collapsed ones are hidden.
   // Phones present the rail as tab sheets (mobileShell.js), which choose what
   // shows; hiding collapsed siblings would empty a sheet and its a11y tree.
-  const exclusive =
-    !isMobile &&
-    shouldHideCollapsedRightPanels({
-      hudVariant: hud.variant,
-      hasExpandedPanel,
-    });
+  const exclusive = !isMobile;
   stack.classList.toggle('layout-exclusive', exclusive);
   for (const panel of panels) {
     if (exclusive && panel.classList.contains('collapsed'))
diff --git a/src/ui/cyberPanelDisclosure.test.mjs b/src/ui/sidePanelDisclosure.test.mjs
similarity index 60%
rename from src/ui/cyberPanelDisclosure.test.mjs
rename to src/ui/sidePanelDisclosure.test.mjs
index e2a666ba5..41b0977f7 100644
--- a/src/ui/cyberPanelDisclosure.test.mjs
+++ b/src/ui/sidePanelDisclosure.test.mjs
@@ -19,6 +19,10 @@ function fixture(theme = 'cyber') {
     nodes.set(id, value);
     return value;
   };
+  const left = node('left-stack');
+  const layers = node('data-panel', false), scenes = node('scene-panel');
+  left.children = [layers, scenes];
+  for (const panel of left.children) panel.parentElement = left;
   const rail = node('rail');
   const display = node('pp-toggles'), context = node('global-context-panel'), cctv = node('cctv-panel'), radio = node('radio-panel');
   rail.children = [display, context, cctv];
@@ -27,6 +31,7 @@ function fixture(theme = 'cyber') {
   radio.parentElement = context;
   const saved = [], claimed = [];
   const owner = {
+    _leftPanelStack: left,
     _rightPanelStack: rail,
     _panelLayout: {},
     _lifetime: { frame() {} },
@@ -36,29 +41,36 @@ function fixture(theme = 'cyber') {
     shareLinkManager: { claimRestoreLane: (...args) => claimed.push(args), onPanelStateChange() {} },
   };
   owner.setPanelCollapsed = PanelChrome.prototype.setPanelCollapsed.bind(owner);
-  return { display, context, cctv, radio, owner, saved, claimed,
+  return { layers, scenes, display, context, cctv, radio, owner, saved, claimed,
     doc: { documentElement: { dataset: { uiTheme: theme } }, getElementById: (id) => nodes.get(id) },
   };
 }
 
-test('explicit Cyber opening collapses peers and claims their restoration lanes', () => {
-  const f = fixture(), prior = globalThis.document;
-  globalThis.document = f.doc;
-  try {
-    f.owner.setPanelCollapsed('global-context-panel', false, { explicit: true });
-    f.owner.setPanelCollapsed('pp-toggles', false, { explicit: true });
-    assert.equal(f.display.classList.contains('collapsed'), false);
-    assert.equal(f.context.classList.contains('collapsed'), true);
-    assert.ok(f.saved.some(([id, collapsed]) => id === 'global-context-panel' && collapsed));
-    assert.ok(f.claimed.some(([, id]) => id === 'global-context-panel'));
-    f.cctv.classList.add('cyber-accordion-collapsed');
-    f.owner.setPanelCollapsed('cctv-panel', true, { explicit: true });
-    assert.equal(f.cctv.classList.contains('cyber-accordion-collapsed'), false);
-  } finally { globalThis.document = prior; }
+test('explicit opening collapses side peers and claims their restoration lanes in every theme', () => {
+  for (const theme of ['tactical', 'minimal', 'cyber']) {
+    const f = fixture(theme), prior = globalThis.document;
+    globalThis.document = f.doc;
+    try {
+      f.owner.setPanelCollapsed('global-context-panel', false, { explicit: true });
+      f.owner.setPanelCollapsed('pp-toggles', false, { explicit: true });
+      assert.equal(f.display.classList.contains('collapsed'), false);
+      assert.equal(f.context.classList.contains('collapsed'), true);
+      assert.ok(f.saved.some(([id, collapsed]) => id === 'global-context-panel' && collapsed));
+      assert.ok(f.claimed.some(([, id]) => id === 'global-context-panel'));
+      f.cctv.classList.add('accordion-collapsed');
+      f.owner.setPanelCollapsed('cctv-panel', true, { explicit: true });
+      assert.equal(f.cctv.classList.contains('accordion-collapsed'), false);
+      // The left side has its own accordion; the right side is untouched.
+      f.owner.setPanelCollapsed('scene-panel', false, { explicit: true });
+      assert.equal(f.scenes.classList.contains('collapsed'), false);
+      assert.equal(f.layers.classList.contains('collapsed'), true);
+      assert.equal(f.display.classList.contains('collapsed'), false);
+    } finally { globalThis.document = prior; }
+  }
 });
 
 test('opening already-expanded Radio reveals Context and closes Display', () => {
-  const f = fixture(), prior = globalThis.document;
+  const f = fixture('tactical'), prior = globalThis.document;
   globalThis.document = f.doc;
   try {
     f.owner.setPanelCollapsed('radio-panel', false, { explicit: true });
@@ -71,17 +83,17 @@ test('opening already-expanded Radio reveals Context and closes Display', () =>
   } finally { globalThis.document = prior; }
 });
 
-test('non-Cyber explicit panels and restored preferences retain their existing policy', () => {
+test('restored preferences keep every saved panel open for the layout to normalize', () => {
   for (const theme of ['tactical', 'minimal', 'cyber']) {
     const f = fixture(theme), prior = globalThis.document;
     globalThis.document = f.doc;
     try {
-      const options = theme === 'cyber' ? { restore: true, persist: false } : { explicit: true };
+      const options = { restore: true, persist: false };
       f.owner.setPanelCollapsed('pp-toggles', false, options);
       f.owner.setPanelCollapsed('cctv-panel', false, options);
       assert.equal(f.display.classList.contains('collapsed'), false);
       assert.equal(f.cctv.classList.contains('collapsed'), false);
-      if (theme === 'cyber') assert.deepEqual(f.saved, []);
+      assert.deepEqual(f.saved, []);
     } finally { globalThis.document = prior; }
   }
 });
diff --git a/src/ui/styles/layers.css b/src/ui/styles/layers.css
index 0f8ed5522..e71cd381c 100644
--- a/src/ui/styles/layers.css
+++ b/src/ui/styles/layers.css
@@ -260,6 +260,9 @@
 #right-context-rail.layout-exclusive > [data-panel-id].collapsed {
   display: none;
 }
+#left-panel-stack.layout-exclusive > [data-panel-id].collapsed {
+  display: none;
+}
 #right-context-rail.layout-focus > [data-panel-id].collapsed {
   display: block;
   flex: 0 0 auto;