feat(panels): render each panel's state classes from the store

A panel's collapsed, dock-pinned, dock-pinned-top, layout-auto-collapsed
and accordion-collapsed classes are drawn by its root's v-panel-state from
the gev-panel-chrome store. PanelChrome, its restore, the layout
controller, both rails and the side accordion present each panel's state
there instead of writing its classes; the rails call onCollapse(panel,
{collapsed, auto}). The directive applies a change in a synchronous
watcher, since the rails measure a panel in the task that opens or closes
it.

Destroying the chrome inside Cockpit now puts back the panels Cockpit's
entry closed while it can still present them. Without a shell, the voice
tools' set_panel_open reports that there is no panel to open. QA scripts
present the states they set instead of writing the classes.

CHANGELOG.md

@@ -108,6 +108,16 @@
   or `onChange`. `UiButton` joins the component kit with ui-vue's props
   (samehkhamis).
 
+- The panels' own state classes (`collapsed`, `dock-pinned`,
+  `dock-pinned-top`, `layout-auto-collapsed`, `accordion-collapsed`) render
+  from the `gev-panel-chrome` store: the shell, the rails and the accordion
+  present each panel's state there instead of writing its classes.
+  `layoutLeftPanelRail` and `layoutRightPanelRail` (`./ui/layout`) now call
+  `onCollapse(panel, {collapsed, auto})` and leave drawing it to the host. Without a
+  shell to own the panels, the voice tools' `set_panel_open` now reports
+  that there is no panel to open instead of writing its classes
+  (samehkhamis).
+
 ## [0.3.0] — 2026-10-27 — Street Level, On Your Phone, in Your Language
 
 - Show a Street Level view facing 359.5° or more as 0°. The viewer caption

docs/VUE-MIGRATION.md

@@ -67,7 +67,13 @@ a feature supplying only its accent.
    mirrors each side's panels and the rail renders from it. Each panel's
    collapse button (`PanelCollapseButton`), the dock tray toggles and the
    dock pins render the open and pinned state PanelChrome presents to the
-   `gev-panel-chrome` store, and their clicks call it there. Done.
+   `gev-panel-chrome` store, and their clicks call it there. Each panel's
+   root draws its own state from there too (`v-panel-state`: `collapsed`,
+   `dock-pinned`, `dock-pinned-top`, `layout-auto-collapsed`,
+   `accordion-collapsed`): PanelChrome, the rails and the accordion present
+   it rather than writing classes. The directive applies it in a synchronous
+   watcher, not on Vue's next render, because the rails measure a panel in
+   the same task that opens or closes it. Done.
 3. **Panels.** Each template and its wiring become a component, keeping ids,
    classes, `data-i18n` text and CSS. The page places each view with a
    `.gev-view` host (`display: contents`), and `mountApplicationViews()`

docs/panel-surfaces.md

@@ -101,7 +101,11 @@ Escape, bound and disposed with `bindPanelDisclosure` /
 `collapsePanelOnEscape` from `panelDisclosure.js` (which bind Escape only). Do not rerun the whole application chrome
 initializer just to add one panel. `layoutLeftPanelRail` and
 `layoutRightPanelRail` accept arbitrary direct `data-panel-id` children; their
-host owns layout scheduling, observations and collapse callbacks. Dynamic
+host owns layout scheduling, observations and collapse callbacks. A rail
+never writes a panel's classes: it calls `onCollapse(panel, {collapsed,
+auto})`, and the host draws that state (the application presents it to the
+panel chrome store, which each root's `v-panel-state` draws at once, so the
+rail can measure the panel in the same task). Dynamic
 content that changes size may require an owner-scheduled layout pass or an
 owned `ResizeObserver`; adding CSS attributes does not register new observers.
 

scripts/package-boundaries.json

@@ -122,7 +122,8 @@
       "src/firstRunCopy.js",
       "src/ui/kit/UiButton.vue",
       "src/ui/stores/panelChrome.js",
-      "src/ui/rail/PanelCollapseButton.vue"
+      "src/ui/rail/PanelCollapseButton.vue",
+      "src/ui/rail/panelState.js"
     ],
     "external": ["vue", "pinia"]
   },
@@ -1048,7 +1049,8 @@
       "src/ui/stores/worldOverlayActions.js",
       "src/ui/stores/awarenessDirection.js",
       "src/ui/stores/hud.js",
-      "src/ui/stores/panelChrome.js"
+      "src/ui/stores/panelChrome.js",
+      "src/ui/rail/panelState.js"
     ],
     "external": ["cesium", "vue", "pinia"]
   },
@@ -3054,7 +3056,8 @@
       "src/ui/stores/hud.js",
       "src/ui/stores/firstRun.js",
       "src/firstRunCopy.js",
-      "src/ui/stores/panelChrome.js"
+      "src/ui/stores/panelChrome.js",
+      "src/ui/rail/panelState.js"
     ],
     "external": [
       "hls.js",
@@ -3863,7 +3866,8 @@
       "src/ui/panelRailCatalog.js",
       "src/ui/panelAccordion.js",
       "src/ui/vueRuntime.js",
-      "src/ui/stores/panelChrome.js"
+      "src/ui/stores/panelChrome.js",
+      "src/ui/rail/panelState.js"
     ],
     "external": ["vue", "pinia"]
   },

scripts/qa-cockpit-utility.mjs

@@ -1799,7 +1799,7 @@ try {
     manager._setCockpitDisplayPortalActive(false);
     document.body.classList.remove('cockpit-mode');
     await waitFrames();
-    standard.classList.remove('collapsed');
+    manager._presentPanel(standard, { collapsed: false });
     standard.style.height = '120px';
     standard.style.maxHeight = '120px';
     standard.style.overflowY = 'auto';
@@ -1834,7 +1834,7 @@ try {
     cockpit.style.height = priorCockpitHeight;
     cockpit.style.maxHeight = priorCockpitMaxHeight;
     cockpit.style.overflowY = priorCockpitOverflow;
-    standard.classList.toggle('collapsed', standardWasCollapsed);
+    manager._presentPanel(standard, { collapsed: standardWasCollapsed });
     return {
       standardBefore,
       standardAfter,

scripts/qa-radio.mjs

@@ -1716,7 +1716,14 @@ async function main() {
           else panel.setAttribute('style', state.style);
           if (state.ariaHidden === null) panel.removeAttribute('aria-hidden');
           else panel.setAttribute('aria-hidden', state.ariaHidden);
-          manager._syncPanelCollapseButton(panel);
+          // The restored classes are the panel's state again.
+          const has = (name) => panel.classList.contains(name);
+          manager._presentPanel(panel, {
+            collapsed: has('collapsed'),
+            pinned: has('dock-pinned'),
+            pinnedTop: has('dock-pinned-top'),
+            auto: has('layout-auto-collapsed') ? 'layout' : has('accordion-collapsed') ? 'accordion' : null,
+          });
         }
         for (const [id, state] of Object.entries(prior.stacks)) {
           const stack = document.getElementById(id);
@@ -1974,7 +1981,7 @@ async function main() {
       manager._setCockpitDisplayPortalActive(true);
       hud.hidden = false;
       signal.hidden = false;
-      dataPanel.classList.remove('collapsed');
+      manager._presentPanel(dataPanel, { collapsed: false });
       window.__godsEyeView.styleManager._syncLeftPanelAdaptiveLayout();
       window.__godsEyeView.styleManager.cockpitView.syncSignalLayout();
       if (display.getAttribute('aria-expanded') === 'true') display.click();
@@ -2059,8 +2066,7 @@ async function main() {
       contextCard.hidden = false;
       // Expand the panel the same way this block already does at entry, so the
       // portaled Display groups measured further down keep their DOM home.
-      dataPanel.classList.remove('collapsed', 'layout-auto-collapsed');
+      manager._presentPanel(dataPanel, { collapsed: false, auto: null });
-      manager._syncPanelCollapseButton(dataPanel);
       manager._syncLeftPanelAdaptiveLayout();
       await waitForLayout();
       const panelRect = dataPanel.getBoundingClientRect();
@@ -2287,7 +2293,14 @@ async function main() {
           else panel.setAttribute('style', state.style);
           if (state.ariaHidden === null) panel.removeAttribute('aria-hidden');
           else panel.setAttribute('aria-hidden', state.ariaHidden);
-          manager._syncPanelCollapseButton(panel);
+          // The restored classes are the panel's state again.
+          const has = (name) => panel.classList.contains(name);
+          manager._presentPanel(panel, {
+            collapsed: has('collapsed'),
+            pinned: has('dock-pinned'),
+            pinnedTop: has('dock-pinned-top'),
+            auto: has('layout-auto-collapsed') ? 'layout' : has('accordion-collapsed') ? 'accordion' : null,
+          });
         }
         manager._panelLayout._leftStackPreferredPanelId = prior.preferredLeftPanelId;
         localStorage.clear();

scripts/qa-visual-input.mjs

@@ -57,7 +57,7 @@ try {
       persist: false,
       syncShare: false,
     });
-    manager._sliderPanel.classList.remove('collapsed');
+    manager._presentPanel(manager._sliderPanel, { collapsed: false });
     const slider = manager._sliderContainer.querySelector('input');
     window.__qaOldSlider = slider;
     const name = 'pixelation';

scripts/qa-weather-journey.mjs

@@ -261,7 +261,7 @@ try {
     for (const [id, entry] of gev.dataManager.layers)
       if (entry.enabled)
         await gev.dataManager.setEnabled(id, false, { origin: 'user' });
-    document.querySelector('#data-panel')?.classList.remove('collapsed');
+    gev.styleManager._presentPanel('data-panel', { collapsed: false });
   });
 
   // 1. Earth view, clean.

src/cockpitMarkup.test.mjs

@@ -1088,7 +1088,7 @@ test('Cockpit Display portals shared HUD, Detection, Parameters, and 3D controls
   );
   assert.match(
     ui,
-    /_revealCockpitStyleParameters\(\{ openDisplay = false \} = \{\}\) \{[\s\S]*?openDisplay[\s\S]*?_setCockpitDisclosure\?\.\('display', true\)[\s\S]*?!this\._cockpitDisclosureOpen\?\.\('display'\)[\s\S]*?classList\.remove\('collapsed'\)/,
+    /_revealCockpitStyleParameters\(\{ openDisplay = false \} = \{\}\) \{[\s\S]*?openDisplay[\s\S]*?_setCockpitDisclosure\?\.\('display', true\)[\s\S]*?!this\._cockpitDisclosureOpen\?\.\('display'\)[\s\S]*?_presentPanel\(this\._sliderPanel, \{ collapsed: false \}\)/,
   );
   assert.match(
     radioBindings,

src/mapSourceFocus.test.mjs

@@ -6,6 +6,7 @@ import assert from 'node:assert/strict';
 import { readFileSync } from 'node:fs';
 import { createPinia } from 'pinia';
 import { msg, t } from './i18n/index.js';
+import { followPanelState, readPanelState } from './ui/rail/panelState.js';
 import { usePanelChromeStore } from './ui/stores/panelChrome.js';
 
 // Exercise the installed event routes and central close method, without WebGL.
@@ -108,18 +109,22 @@ function harness({ hidden = false, selected = true, noChips = false } = {}) {
   window.clearTimeout = (id) => timers.delete(id);
   window.performance = { now: () => now };
   document.defaultView = window;
-  const methods = new Function('createHoverDisclosure', 'collapsePanelOnEscape', 'document', 'window', 'clearTimeout', 'performance', 'requestAnimationFrame', 't', 'msg',
+  const methods = new Function('createHoverDisclosure', 'collapsePanelOnEscape', 'document', 'window', 'clearTimeout', 'performance', 'requestAnimationFrame', 't', 'msg', 'readPanelState',
-    `return ({${shellMethod('_initAutoHoverPanel').toString()},\n${shellMethod('_collapsePanelOnEscape').toString()},\n${shellMethod('setPanelCollapsed').toString()},\n${shellMethod('_syncPanelCollapseButton').toString()}});`)(
+    `return ({${shellMethod('_initAutoHoverPanel').toString()},\n${shellMethod('_collapsePanelOnEscape').toString()},\n${shellMethod('setPanelCollapsed').toString()},\n${shellMethod('_presentPanel').toString()}});`)(
-    createHoverDisclosure, collapsePanelOnEscape, document, window, (id) => timers.delete(id), { now: () => now }, () => {}, t, msg,
+    createHoverDisclosure, collapsePanelOnEscape, document, window, (id) => timers.delete(id), { now: () => now }, () => {}, t, msg, readPanelState,
   );
   const saves = [];
   const claims = [];
   let shareSyncs = 0;
   const chromeStore = usePanelChromeStore(createPinia());
+  const chromeToken = chromeStore.connect({});
+  // The trays' roots draw the store's state, as v-panel-state does.
+  followPanelState(chromeStore, 'control-panel', panel);
+  followPanelState(chromeStore, 'location-bar', location);
   const manager = {
     _lifetime: { frame() {} },
     _chromeStore: chromeStore,
-    _chromeToken: chromeStore.connect({}),
+    _chromeToken: chromeToken,
     _panelLayout: { _leftStackPreferredPanelId: null, _rightStackPreferredPanelId: null },
     ...methods,
     _savePanelCollapsedState(...args) { saves.push(args); },

src/panelStackLayout.test.mjs

@@ -141,8 +141,8 @@ test('desktop panel lanes use per-panel allocations and presentation-only auto-c
   const ui = readShellSource();
   const css = readStylesheet(new URL('../style.css', import.meta.url));
   assert.doesNotMatch(ui, /_enforce(?:Left|Right)PanelAccordion/);
-  assert.match(rails, /classList\.add\('collapsed', 'layout-auto-collapsed'\)/);
+  assert.match(rails, /onCollapse\(panel, \{ collapsed: true, auto: 'layout' \}\)/);
-  assert.match(readFileSync(new URL('./ui/panelLayoutController.js', import.meta.url), 'utf8'), /classList\.remove\('collapsed', 'layout-auto-collapsed'\)/);
+  assert.match(readFileSync(new URL('./ui/panelLayoutController.js', import.meta.url), 'utf8'), /_presentPanel\(panel, \{ collapsed: false, auto: null \}\)/);
   assert.match(ui, /reconsiderAutoCollapse/);
   assert.match(
     ui,
@@ -169,7 +169,7 @@ test('desktop panel lanes use per-panel allocations and presentation-only auto-c
   assert.match(rightRail, /focusedExpandedPanel = expandedPanelsInDomOrder\.find\(\s*\(panel\) =>\s*panel\.contains\(documentRef\.activeElement\),?\s*\)/);
   // Collapse buttons render aria-expanded from the state the chrome presents
   // (panelChromeButtons.test.mjs covers the views).
-  assert.match(ui, /_chromeStore\.publish\(this\._chromeToken, panelEl\.id, \{\s*collapsed: panelEl\.classList\.contains\('collapsed'\),/);
+  assert.match(ui, /this\._presentPanel\(panelEl, \{ collapsed: nextCollapsed, auto: null \}\)/);
   assert.match(leftRail, /--left-panel-allocated-height/);
   assert.match(rightRail, /--right-panel-allocated-height/);
   assert.match(

src/radioMarkup.test.mjs

@@ -359,7 +359,7 @@ test('panel collapse is presentation-only and Radio exposes explicit voice playb
   assert.doesNotMatch(enableMethod, /contextRadio/);
   assert.match(enableMethod, /toggleRadio\(this\._radioEnableBtn\)/);
   // The collapse buttons render aria-expanded from the state the chrome presents.
-  assert.match(ui, /_chromeStore\.publish\(this\._chromeToken, panelEl\.id, \{/);
+  assert.match(ui, /this\._presentPanel\(panelEl, \{ collapsed: nextCollapsed, auto: null \}\)/);
   assert.doesNotMatch(method, /panelId === 'global-context-panel'[\s\S]*?this\._radioState\?\.enabled[\s\S]*?setPanelCollapsed\('radio-panel', false\)/);
 });
 

src/testSupport/panelState.mjs

@@ -0,0 +1,21 @@
+// src/testSupport/panelState.mjs — present a panel's state the way the shell
+// does (PanelChrome._presentPanel), drawn at once as its root's v-panel-state
+// would, for fixtures whose panels are plain objects with a classList.
+import { applyPanelState, readPanelState } from '../ui/rail/panelState.js';
+
+/**
+ * @param {object|string} panelOrId A panel, or its id in `documentRef`.
+ * @param {object} [patch] The state that changes.
+ * @param {Document} [documentRef]
+ */
+export function presentPanelLocally(
+  panelOrId,
+  patch = {},
+  documentRef = globalThis.document,
+) {
+  const panel =
+    typeof panelOrId === 'string'
+      ? documentRef?.getElementById(panelOrId)
+      : panelOrId;
+  if (panel) applyPanelState(panel, { ...readPanelState(panel), ...patch });
+}

src/tooling/panelStorageDocs.test.mjs

@@ -77,13 +77,14 @@ test('the documented outcomes hold: default, stored open, stored shut, and a sha
   // against the code that decides them.
   const { PanelPositionControls } =
     await import('../ui/panelPositionControls.js');
+  const { presentPanelLocally } = await import('../testSupport/panelState.mjs');
   const html = await readFile(
     path.join(root, 'src/ui/views/panels/CctvPanel.vue'),
     'utf8',
   );
   assert.match(
     html,
-    /<div id="cctv-panel" class="panel-collapsible collapsed"/,
+    /<div id="cctv-panel"[^>]*class="panel-collapsible collapsed"/,
     'the CCTV panel starts collapsed in the markup',
   );
 
@@ -110,7 +111,7 @@ test('the documented outcomes hold: default, stored open, stored shut, and a sha
   };
   try {
     const controls = new PanelPositionControls({
-      syncPanelCollapseButton: () => {},
+      presentPanel: presentPanelLocally,
       layoutRightPanels: () => {},
       syncCctvPanelViewport: () => {},
       showToast: () => {},

src/ui/applicationShell.js

@@ -234,8 +234,7 @@ export class StyleManager extends ShellFacade {
         _setCockpitDisclosure: (...args) => this._setCockpitDisclosure(...args),
         _cockpitDisclosureOpen: (kind) => this._cockpitDisclosureOpen(kind),
         _setMapStack: (...args) => this._setMapStack(...args),
-        _syncPanelCollapseButton: (...args) =>
+        _presentPanel: (...args) => this._presentPanel(...args),
-          this._syncPanelCollapseButton(...args),
         _syncShareState: (...args) => this._syncShareState(...args),
         setPanelCollapsed: (...args) => this.setPanelCollapsed(...args),
       },

src/ui/leftPanelRail.js

@@ -17,7 +17,8 @@ import { settleSideAccordion } from './panelAccordion.js';
  * @param {Window} options.windowRef Viewport and style reader.
  * @param {{visible: boolean, variant: string}} options.hud Current HUD presentation.
  * @param {string} options.preferredPanelId Most recently opened panel.
- * @param {Function} options.onCollapse Update a panel's disclosure chrome.
+ * @param {Function} options.onCollapse Present a panel's collapse:
+ *   `(panel, {collapsed, auto})`.
  * @param {Function} options.onRetry Request another pass after automatic collapse.
  * @param {Function} [options.getComputedStyle] Optional DOM style reader override.
  * @param {Map<string, number>} options.collapsedHeights Caller-owned measurement cache.
@@ -45,8 +46,7 @@ export function layoutLeftPanelRail({
     for (const panel of panels.filter((item) =>
       item.classList.contains('layout-auto-collapsed'),
     )) {
-      panel.classList.remove('collapsed', 'layout-auto-collapsed');
+      onCollapse(panel, { collapsed: false, auto: null });
-      onCollapse(panel);
     }
   }
 
@@ -262,8 +262,7 @@ export function layoutLeftPanelRail({
   if (autoCollapseIndices.length) {
     for (const index of autoCollapseIndices) {
       const panel = expandedPanels[index];
-      panel.classList.add('collapsed', 'layout-auto-collapsed');
+      onCollapse(panel, { collapsed: true, auto: 'layout' });
-      onCollapse(panel);
     }
     onRetry();
     return;

src/ui/panelAccordion.js

@@ -9,7 +9,8 @@
  * @param {boolean} options.enabled Whether the one-panel rule applies.
  * @param {string} [options.preferredPanelId] Most recently opened panel.
  * @param {Document} [options.documentRef] Document supplying keyboard focus.
- * @param {Function} options.onCollapse Update a panel's disclosure chrome.
+ * @param {Function} options.onCollapse Present a panel's collapse:
+ *   `(panel, {collapsed, auto})`.
  */
 export function settleSideAccordion({
   panels,
@@ -21,8 +22,7 @@ export function settleSideAccordion({
   if (!enabled) {
     for (const panel of panels) {
       if (!panel.classList.contains('accordion-collapsed')) continue;
-      panel.classList.remove('collapsed', 'accordion-collapsed');
+      onCollapse(panel, { collapsed: false, auto: null });
-      onCollapse(panel);
     }
     return;
   }
@@ -35,7 +35,6 @@ export function settleSideAccordion({
     expanded[0];
   for (const panel of expanded) {
     if (panel === owner) continue;
-    panel.classList.add('collapsed', 'accordion-collapsed');
+    onCollapse(panel, { collapsed: true, auto: 'accordion' });
-    onCollapse(panel);
   }
 }

src/ui/panelChrome.js

@@ -1,4 +1,5 @@
 import { UiLifetime } from './uiLifetime.js';
+import { readPanelState } from './rail/panelState.js';
 import { usePanelChromeStore } from './stores/panelChrome.js';
 import { applicationPinia } from './vueRuntime.js';
 import { displayPanelScroller } from './displayPanelScroll.js';
@@ -81,7 +82,7 @@ export class PanelChrome {
     this._cockpitPanelRestore = null;
     this._cockpitContextCollapsedForDataPanel = false;
     this._panelPosition = new PanelPositionControls({
-      syncPanelCollapseButton: (panel) => this._syncPanelCollapseButton(panel),
+      presentPanel: (panel, patch) => this._presentPanel(panel, patch),
       showToast: (message) => this._showToast(message),
     });
     this._panelLayout = new PanelLayoutController({
@@ -90,7 +91,7 @@ export class PanelChrome {
         variant: this.hud.getVariant(),
       }),
       scheduleCockpitLayout: () => this.cockpitView?.scheduleContextLayout(),
-      syncPanelCollapseButton: (panel) => this._syncPanelCollapseButton(panel),
+      presentPanel: (panel, patch) => this._presentPanel(panel, patch),
       readDisplayScrollTop: () =>
         this._displayPortalScrollRestoreOwner === 'standard'
           ? this._standardDisplayScrollTop
@@ -221,18 +222,18 @@ export class PanelChrome {
       typeof pin === 'boolean'
         ? pin
         : !panelEl.classList.contains('dock-pinned');
-    panelEl.classList.toggle('dock-pinned', shouldPin);
+    // The tray pinned last draws on top; unpinning hands the top to the
-    this._chromeStore.publish(this._chromeToken, panelId, {
+    // other tray if it is pinned.
-      collapsed: panelEl.classList.contains('collapsed'),
+    this._presentPanel(panelEl, { pinned: shouldPin, pinnedTop: shouldPin });
-      pinned: shouldPin,
+    for (const otherId of PINNABLE_PANEL_IDS) {
-    });
+      if (otherId === panelId) continue;
-    document
+      const other = document.getElementById(otherId);
-      .querySelectorAll('#command-dock .dock-pinned-top')
+      if (!other) continue;
-      .forEach((pinnedPanel) => {
+      this._presentPanel(other, {
-        pinnedPanel.classList.remove('dock-pinned-top');
+        pinnedTop: !shouldPin && other.classList.contains('dock-pinned'),
       });
+    }
     if (shouldPin) {
-      panelEl.classList.add('dock-pinned-top');
       this.setPanelCollapsed(panelId, false, {
         explicit: !restore,
         restore,
@@ -240,10 +241,6 @@ export class PanelChrome {
         syncShare: false,
       });
     } else {
-      const remainingPinnedPanel = document.querySelector(
-        '#command-dock .dock-pinned',
-      );
-      remainingPinnedPanel?.classList.add('dock-pinned-top');
       if (!restore && !panelEl.matches(':hover')) {
         this.setPanelCollapsed(panelId, true, {
           explicit: true,
@@ -323,11 +320,23 @@ export class PanelChrome {
     return this._panelLayout._scheduleLeftPanelLayout(options0);
   }
 
-  /** Present a panel's open state to its collapse and dock buttons. */
+  /**
-  _syncPanelCollapseButton(panelEl) {
+   * Present a panel's state, merged over what it shows now, to the panel
+   * chrome store; its root and buttons draw it from there.
+   * @param {Element|string} panelOrId
+   * @param {Partial<import('./stores/panelChrome.js').PanelState>} [patch]
+   */
+  _presentPanel(panelOrId, patch = {}) {
+    const panelEl =
+      typeof panelOrId === 'string'
+        ? document.getElementById(panelOrId)
+        : panelOrId;
     if (!panelEl?.id) return;
+    const shown =
+      this._chromeStore.panels[panelEl.id] ?? readPanelState(panelEl);
     this._chromeStore.publish(this._chromeToken, panelEl.id, {
-      collapsed: panelEl.classList.contains('collapsed'),
+      ...shown,
+      ...patch,
     });
   }
 
@@ -478,7 +487,6 @@ export class PanelChrome {
       panelEl.classList.contains('collapsed') === nextCollapsed &&
       !wasAutoCollapsed
     ) {
-      this._syncPanelCollapseButton(panelEl);
       if (priorLeftOwner !== this._panelLayout._leftStackPreferredPanelId) {
         this._scheduleLeftPanelLayout({ reconsiderAutoCollapse: true });
       }
@@ -487,7 +495,6 @@ export class PanelChrome {
       }
       return;
     }
-    panelEl.classList.remove('layout-auto-collapsed', 'accordion-collapsed');
     if (
       !nextCollapsed &&
       this.cockpitView?.active &&
@@ -518,7 +525,7 @@ export class PanelChrome {
         });
       }
     }
-    panelEl.classList.toggle('collapsed', nextCollapsed);
+    this._presentPanel(panelEl, { collapsed: nextCollapsed, auto: null });
     if (
       nextCollapsed &&
       this.cockpitView?.active &&
@@ -528,7 +535,6 @@ export class PanelChrome {
       this._cockpitContextCollapsedForDataPanel = false;
       this.cockpitView.setContextCollapsed(false);
     }
-    this._syncPanelCollapseButton(panelEl);
     if (persist !== false)
       this._savePanelCollapsedState(panelId, nextCollapsed);
     if (panelId === 'pp-toggles') {
@@ -586,6 +592,9 @@ export class PanelChrome {
   }
   destroy() {
     if (this._disposed) return;
+    // Cockpit's own teardown follows the chrome's: put back the panels its
+    // entry closed while this owner can still present them.
+    this.exitCockpit();
     this._disposed = true;
     this._lifetime.destroy();
     this._chromeStore.detach(this._chromeToken);

src/ui/panelChromeButtons.test.mjs

@@ -4,9 +4,11 @@
 import '../testSupport/registerDom.mjs';
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { createApp, h, nextTick } from 'vue';
+import { createApp, h, nextTick, withDirectives } from 'vue';
 import { createPinia } from 'pinia';
+import { settleSideAccordion } from './panelAccordion.js';
 import { PanelChrome } from './panelChrome.js';
+import { followPanelState, vPanelState } from './rail/panelState.js';
 import { bindPanelDisclosure } from './panelDisclosure.js';
 import PanelCollapseButton from './rail/PanelCollapseButton.vue';
 import { usePanelChromeStore } from './stores/panelChrome.js';
@@ -30,6 +32,8 @@ test('the store republishes a panel only when its state changes', () => {
   assert.deepEqual(store.panels['data-panel'], {
     collapsed: true,
     pinned: false,
+    pinnedTop: false,
+    auto: null,
   });
   store.publish(token, 'data-panel', { collapsed: true });
   assert.ok(store.panels === first, 'an unchanged state is not republished');
@@ -175,6 +179,8 @@ test('PanelChrome takes clicks only once initialized, pins only dock trays, and
     <div id="control-panel" class="collapsed"></div>`;
   const store = usePanelChromeStore(createPinia());
   const chrome = panelChrome(store);
+  for (const id of ['data-panel', 'cctv-panel', 'control-panel'])
+    followPanelState(store, id, document.getElementById(id));
   const calls = [];
   const setPanelCollapsed = chrome.setPanelCollapsed.bind(chrome);
   chrome.setPanelCollapsed = (id, collapsed, options) => {
@@ -196,6 +202,8 @@ test('PanelChrome takes clicks only once initialized, pins only dock trays, and
   assert.deepEqual(store.panels['control-panel'], {
     collapsed: false,
     pinned: true,
+    pinnedTop: true,
+    auto: null,
   });
   assert.equal(
     document.getElementById('control-panel').classList.contains('dock-pinned'),
@@ -206,8 +214,12 @@ test('PanelChrome takes clicks only once initialized, pins only dock trays, and
   const before = calls.length;
   store.act('toggle', 'data-panel');
   assert.equal(calls.length, before, 'a destroyed owner gets no clicks');
-  chrome._syncPanelCollapseButton(document.getElementById('cctv-panel'));
+  chrome._presentPanel('cctv-panel', { collapsed: true });
   assert.equal(store.panels['cctv-panel'], undefined, 'nor publishes');
+  assert.equal(
+    document.getElementById('cctv-panel').classList.contains('collapsed'),
+    false,
+  );
 });
 
 test('a remounted chrome starts from its own states, not a pin left behind', () => {
@@ -221,10 +233,12 @@ test('a remounted chrome starts from its own states, not a pin left behind', ()
   document.body.innerHTML = '<div id="location-bar" class="collapsed"></div>';
   const second = panelChrome(store);
   assert.equal(store.panels['location-bar'], undefined);
-  second._syncPanelCollapseButton(document.getElementById('location-bar'));
+  second._presentPanel('location-bar');
   assert.deepEqual(store.panels['location-bar'], {
     collapsed: true,
     pinned: false,
+    pinnedTop: false,
+    auto: null,
   });
   second.destroy();
 });
@@ -238,3 +252,80 @@ test('bindPanelDisclosure refuses the retired button wiring', () => {
     );
   }
 });
+
+test('a panel root draws its state at once, keeping classes others own', async (t) => {
+  const store = mount(t, {
+    render: () =>
+      withDirectives(
+        h('div', { id: 'scene-panel', class: 'panel-collapsible collapsed' }),
+        [[vPanelState, 'scene-panel']],
+      ),
+  });
+  const panel = document.getElementById('scene-panel');
+  panel.classList.add('running');
+  assert.equal(panel.classList.contains('collapsed'), true, 'markup stands');
+  const token = store.connect({});
+  store.publish(token, 'scene-panel', { collapsed: true, auto: 'accordion' });
+  // No tick: a layout measures in the same task.
+  assert.equal(panel.classList.contains('accordion-collapsed'), true);
+  store.publish(token, 'scene-panel', { collapsed: false, auto: null });
+  assert.equal(panel.classList.contains('collapsed'), false);
+  assert.equal(panel.classList.contains('accordion-collapsed'), false);
+  assert.equal(panel.classList.contains('running'), true);
+  assert.equal(panel.classList.contains('panel-collapsible'), true);
+  store.publish(token, 'scene-panel', { pinned: true, pinnedTop: true });
+  assert.ok(panel.classList.contains('dock-pinned'));
+  assert.ok(panel.classList.contains('dock-pinned-top'));
+});
+
+test('destroying the chrome inside Cockpit puts back the panels its entry closed', () => {
+  document.body.innerHTML = `
+    <div id="data-panel"></div>
+    <div id="cctv-panel" class="collapsed"></div>`;
+  const store = usePanelChromeStore(createPinia());
+  const chrome = panelChrome(store);
+  const data = document.getElementById('data-panel');
+  followPanelState(store, 'data-panel', data);
+  chrome.enterCockpit();
+  assert.equal(data.classList.contains('collapsed'), true);
+  chrome.destroy();
+  assert.equal(data.classList.contains('collapsed'), false);
+  chrome.exitCockpit();
+  assert.equal(data.classList.contains('collapsed'), false);
+});
+
+test('the accordion closes peers through the real store, and opens them again', () => {
+  document.body.innerHTML = `
+    <div id="data-panel" data-panel-id="data-panel"></div>
+    <div id="scene-panel" data-panel-id="scene-panel"></div>`;
+  const store = usePanelChromeStore(createPinia());
+  const chrome = panelChrome(store);
+  const panels = ['data-panel', 'scene-panel'].map((id) => {
+    const panel = document.getElementById(id);
+    followPanelState(store, id, panel);
+    return panel;
+  });
+  const onCollapse = (panel, patch) => chrome._presentPanel(panel, patch);
+  settleSideAccordion({
+    panels,
+    enabled: true,
+    preferredPanelId: 'scene-panel',
+    documentRef: document,
+    onCollapse,
+  });
+  assert.deepEqual(store.panels['data-panel'], {
+    collapsed: true,
+    pinned: false,
+    pinnedTop: false,
+    auto: 'accordion',
+  });
+  assert.equal(panels[0].className, 'collapsed accordion-collapsed');
+  assert.equal(
+    store.panels['scene-panel'],
+    undefined,
+    'the owner is untouched',
+  );
+  settleSideAccordion({ panels, enabled: false, onCollapse });
+  assert.equal(panels[0].className, '');
+  chrome.destroy();
+});

src/ui/panelLayoutController.js

@@ -64,12 +64,12 @@ export class PanelLayoutController {
   constructor({
     readHud,
     scheduleCockpitLayout,
-    syncPanelCollapseButton,
+    presentPanel,
     readDisplayScrollTop,
   }) {
     this.readHud = readHud;
     this.scheduleCockpitLayout = scheduleCockpitLayout;
-    this._syncPanelCollapseButton = syncPanelCollapseButton;
+    this._presentPanel = presentPanel;
     this.readDisplayScrollTop = readDisplayScrollTop;
     this.destroyed = false;
     this._adaptivePanelSettleTimer = null;
@@ -198,7 +198,6 @@ export class PanelLayoutController {
     ]) {
       if (!panel) continue;
       stack.insertBefore(panel, globalContextPanel);
-      this._syncPanelCollapseButton(panel);
     }
     if (this._sliderPanel) {
       this._sliderPanel.style.removeProperty('top');
@@ -286,8 +285,7 @@ export class PanelLayoutController {
         for (const panel of this._rightPanelStack.querySelectorAll(
           '.layout-auto-collapsed',
         )) {
-          panel.classList.remove('collapsed', 'layout-auto-collapsed');
+          this._presentPanel(panel, { collapsed: false, auto: null });
-          this._syncPanelCollapseButton(panel);
         }
       }
       this._syncRightPanelAdaptiveLayout();
@@ -303,7 +301,7 @@ export class PanelLayoutController {
       windowRef: window,
       hud: this.readHud(),
       preferredPanelId: this._rightStackPreferredPanelId,
-      onCollapse: (panel) => this._syncPanelCollapseButton(panel),
+      onCollapse: (panel, patch) => this._presentPanel(panel, patch),
       onRetry: () => this._scheduleRightPanelLayout(),
       leftStack: this._leftPanelStack,
       displayPanel: this._ppToggles,
@@ -422,8 +420,7 @@ export class PanelLayoutController {
         for (const panel of this._leftPanelStack.querySelectorAll(
           '.layout-auto-collapsed',
         )) {
-          panel.classList.remove('collapsed', 'layout-auto-collapsed');
+          this._presentPanel(panel, { collapsed: false, auto: null });
-          this._syncPanelCollapseButton(panel);
         }
       }
       this._syncLeftPanelAdaptiveLayout();
@@ -438,7 +435,7 @@ export class PanelLayoutController {
       windowRef: window,
       hud: this.readHud(),
       preferredPanelId: this._leftStackPreferredPanelId,
-      onCollapse: (panel) => this._syncPanelCollapseButton(panel),
+      onCollapse: (panel, patch) => this._presentPanel(panel, patch),
       onRetry: () => this._scheduleLeftPanelLayout(),
       collapsedHeights: this._leftStackCollapsedHeights,
       onAligned: () => this._scheduleRightPanelLayout(),

src/ui/panelPositionControls.js

@@ -14,8 +14,8 @@ const RETIRED_PANEL_KEY_PREFIXES = [
   `godsEyeView.${PANEL_POSITION_STORAGE_VERSION}.panelFloatHintShown`,
 ];
 export class PanelPositionControls {
-  constructor({ syncPanelCollapseButton, showToast }) {
+  constructor({ presentPanel, showToast }) {
-    this._syncPanelCollapseButton = syncPanelCollapseButton;
+    this._presentPanel = presentPanel;
     this._showToast = showToast;
   }
 
@@ -75,7 +75,7 @@ export class PanelPositionControls {
     // first-run mission card for the one first impression there is. A stored
     // choice still wins in both directions, so anyone who opens it keeps it.
     if (panelId === 'pp-toggles' && stored === null) collapsed = true;
-    panelEl.classList.toggle('collapsed', collapsed);
+    this._presentPanel(panelEl, { collapsed });
     // Bodies that expand themselves on first appearance must not override a
     // choice the user (or a share link) already made.
     if (panelEl.dataset)
@@ -84,7 +84,6 @@ export class PanelPositionControls {
         : stored === null
           ? 'default'
           : 'stored';
-    this._syncPanelCollapseButton(panelEl);
   }
 
   _savePanelCollapsedState(panelId, collapsed) {

src/ui/panelRails.test.mjs

@@ -7,6 +7,7 @@ import {
   layoutRightPanelRail,
   measurePanelNaturalHeight,
 } from './panelRails.js';
+import { applyPanelState, readPanelState } from './rail/panelState.js';
 
 test('Display uses an inner scroll body only in Cyber', () => {
   const body = { scrollTop: 95 };
@@ -169,7 +170,11 @@ function fixture(
       matchMedia: () => ({ matches: mobile }),
       getComputedStyle: (node) => node.computed,
     },
-    onCollapse: (panel) => collapsed.push(panel.id),
+    // The owner presents the patch; the panel's root draws it at once.
+    onCollapse: (panel, patch) => {
+      collapsed.push(panel.id);
+      applyPanelState(panel, { ...readPanelState(panel), ...patch });
+    },
     onRetry: () => {
       retries += 1;
     },

src/ui/rail/panelState.js

@@ -0,0 +1,70 @@
+import { watch } from 'vue';
+import { usePanelChromeStore } from '../stores/panelChrome.js';
+
+/** The classes a panel's state draws on its root. */
+const CLASSES = Object.freeze({
+  collapsed: (state) => state.collapsed,
+  'dock-pinned': (state) => state.pinned,
+  'dock-pinned-top': (state) => state.pinnedTop,
+  'layout-auto-collapsed': (state) => state.auto === 'layout',
+  'accordion-collapsed': (state) => state.auto === 'accordion',
+});
+
+/**
+ * Draw `state` on a panel's root with `classList`, leaving other classes.
+ * @param {Element} el
+ * @param {import('../stores/panelChrome.js').PanelState} state
+ */
+export function applyPanelState(el, state) {
+  for (const [name, on] of Object.entries(CLASSES))
+    if (el.classList.contains(name) !== on(state))
+      el.classList.toggle(name, on(state));
+}
+
+/**
+ * Keep `el` drawing the state `store` holds for `panelId`, synchronously:
+ * the panel layouts measure a panel in the same task that opens or closes
+ * it. Until the panel is presented its markup's classes stand.
+ * @returns {() => void} Stops following the store.
+ */
+export function followPanelState(store, panelId, el) {
+  return watch(
+    () => store.panels[panelId],
+    (state) => state && applyPanelState(el, state),
+    { flush: 'sync', immediate: true },
+  );
+}
+
+/**
+ * `v-panel-state="'data-panel'"`: the panel root draws its open, pinned and
+ * layout-collapsed state from the panel chrome store.
+ */
+export const vPanelState = {
+  mounted(el, binding) {
+    const store = usePanelChromeStore(binding.instance.$pinia);
+    el._stopPanelState = followPanelState(store, binding.value, el);
+  },
+  beforeUnmount(el) {
+    el._stopPanelState?.();
+  },
+};
+
+/**
+ * A panel's state as its classes draw it: the markup's state, before its
+ * owner first presents the panel.
+ * @param {Element} el
+ * @returns {import('../stores/panelChrome.js').PanelState}
+ */
+export function readPanelState(el) {
+  const has = (name) => el.classList.contains(name);
+  return {
+    collapsed: has('collapsed'),
+    pinned: has('dock-pinned'),
+    pinnedTop: has('dock-pinned-top'),
+    auto: has('layout-auto-collapsed')
+      ? 'layout'
+      : has('accordion-collapsed')
+        ? 'accordion'
+        : null,
+  };
+}

src/ui/rightPanelRail.js

@@ -41,7 +41,8 @@ function settledLeftRailTop(leftStack, viewportHeight, getComputedStyle) {
  * @param {Window} options.windowRef Viewport and style reader.
  * @param {{visible: boolean, variant: string}} options.hud Current HUD presentation.
  * @param {string} options.preferredPanelId Most recently opened panel.
- * @param {Function} options.onCollapse Update a panel's disclosure chrome.
+ * @param {Function} options.onCollapse Present a panel's collapse:
+ *   `(panel, {collapsed, auto})`.
  * @param {Function} options.onRetry Request another pass after automatic collapse.
  * @param {Function} [options.getComputedStyle] Optional DOM style reader override.
  * @param {HTMLElement} options.leftStack Rail supplying the shared top baseline.
@@ -83,8 +84,7 @@ export function layoutRightPanelRail({
     for (const panel of panels.filter((item) =>
       item.classList.contains('layout-auto-collapsed'),
     )) {
-      panel.classList.remove('collapsed', 'layout-auto-collapsed');
+      onCollapse(panel, { collapsed: false, auto: null });
-      onCollapse(panel);
     }
   }
   // One panel is open per desktop side; this marker is distinct from
@@ -275,8 +275,7 @@ export function layoutRightPanelRail({
   if (!isCollapseRetry && autoCollapseIndices.length) {
     for (const index of autoCollapseIndices) {
       const panel = expandedPanels[index];
-      panel.classList.add('collapsed', 'layout-auto-collapsed');
+      onCollapse(panel, { collapsed: true, auto: 'layout' });
-      onCollapse(panel);
     }
     pendingCollapseRetries.add(stack);
     onRetry();

src/ui/shellFacade.js

@@ -1024,13 +1024,14 @@ export class ShellFacade {
   }
 
   /**
-   * Updates collapse button glyphs based on panel state. Right-rail panels
+   * Presents a panel's state, merged over what it shows now; its root and
-   * use directional arrows; left-stack panels use +/- symbols.
+   * buttons draw it from the panel chrome store.
-   * @param {HTMLElement} panelEl - The panel DOM element.
+   * @param {HTMLElement|string} panelOrId - The panel or its id.
+   * @param {object} [patch] - The state that changes.
    * @returns {void}
    */
-  _syncPanelCollapseButton(panelEl) {
+  _presentPanel(panelOrId, patch) {
-    return this._panelChrome._syncPanelCollapseButton(...arguments);
+    return this._panelChrome._presentPanel(...arguments);
   }
 
   _buildSharePanelState() {

src/ui/shellLifecycle.test.mjs

@@ -3,6 +3,7 @@ import assert from 'node:assert/strict';
 import { UiLifetime } from './uiLifetime.js';
 import { createPinia } from 'pinia';
 import { PanelChrome } from './panelChrome.js';
+import { followPanelState } from './rail/panelState.js';
 import { usePanelChromeStore } from './stores/panelChrome.js';
 import { PanelLayoutController } from './panelLayoutController.js';
 import { ShellFeedback } from './shellFeedback.js';
@@ -150,7 +151,7 @@ test('panel layout coalesces each rail and cannot rearm after destruction', () =
     const owner = new PanelLayoutController({
       readHud: () => ({}),
       scheduleCockpitLayout() {},
-      syncPanelCollapseButton() {},
+      presentPanel() {},
       readDisplayScrollTop: () => 0,
     });
     owner._syncLeftPanelAdaptiveLayout = () => layouts++;
@@ -257,7 +258,7 @@ test('recording restores the original HUD after repeated entry and revokes retai
   }
 });
 
-test('weather rail orders between CCTV and Context, observes and syncs chrome', (t) => {
+test('weather rail orders between CCTV and Context, observes and presents chrome', (t) => {
   const f = fixture();
   const observed = new Set();
   const previousResizeObserver = globalThis.ResizeObserver;
@@ -298,16 +299,16 @@ test('weather rail orders between CCTV and Context, observes and syncs chrome',
     }
     const weather = f.nodes.get('weather-panel');
     stack.children = [weather, f.nodes.get('global-context-panel')];
-    const synced = [];
     const store = usePanelChromeStore(createPinia());
     const chrome = { _chromeStore: store, _chromeToken: store.connect({}) };
+    const presented = [];
     const owner = new PanelLayoutController({
       readHud: () => ({}),
       scheduleCockpitLayout() {},
       readDisplayScrollTop: () => 0,
-      syncPanelCollapseButton(panel) {
+      presentPanel(panel, patch) {
-        synced.push(panel.id);
+        presented.push(panel.id);
-        PanelChrome.prototype._syncPanelCollapseButton.call(chrome, panel);
+        PanelChrome.prototype._presentPanel.call(chrome, panel, patch);
       },
     });
     owner._initRightPanelAdaptiveLayout();
@@ -315,12 +316,15 @@ test('weather rail orders between CCTV and Context, observes and syncs chrome',
       stack.children.map((panel) => panel.id),
       ['pp-toggles', 'cctv-panel', 'weather-panel', 'global-context-panel'],
     );
-    assert.ok(synced.includes('weather-panel'));
     assert.ok(observed.has(weather));
-    assert.equal(store.panels['weather-panel'].collapsed, true);
+    // Moving a panel into the rail leaves its state as it was.
-    weather.classList.remove('collapsed');
+    assert.deepEqual(presented, []);
-    PanelChrome.prototype._syncPanelCollapseButton.call(chrome, weather);
+    followPanelState(store, 'weather-panel', weather);
+    PanelChrome.prototype._presentPanel.call(chrome, weather, {
+      collapsed: false,
+    });
     assert.equal(store.panels['weather-panel'].collapsed, false);
+    assert.equal(weather.classList.contains('collapsed'), false);
     owner.destroy();
     assert.equal(observed.size, 0);
     assert.equal(f.frames.size, 0);

src/ui/sidePanelDisclosure.test.mjs

@@ -1,6 +1,7 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import { PanelChrome } from './panelChrome.js';
+import { presentPanelLocally } from '../testSupport/panelState.mjs';
 
 function fixture(theme = 'cyber') {
   const nodes = new Map();
@@ -35,7 +36,7 @@ function fixture(theme = 'cyber') {
     _rightPanelStack: rail,
     _panelLayout: {},
     _lifetime: { frame() {} },
-    _syncPanelCollapseButton() {}, _scheduleRightPanelLayout() {},
+    _presentPanel: presentPanelLocally, _scheduleRightPanelLayout() {},
     _scheduleLeftPanelLayout() {}, _layoutRightPanels() {}, _syncCctvPanelViewport() {},
     _savePanelCollapsedState: (...args) => saved.push(args),
     shareLinkManager: { claimRestoreLane: (...args) => claimed.push(args), onPanelStateChange() {} },

src/ui/stores/panelChrome.js

@@ -8,15 +8,35 @@ import { shallowRef } from 'vue';
  */
 
 /**
- * Each panel's disclosure state as its collapse, dock and pin buttons render
+ * @typedef {object} PanelState
- * it. PanelChrome owns the panels: it publishes here whenever a panel opens,
+ * @property {boolean} collapsed Whether the panel is closed, by the person or
- * closes or is pinned, and connects the buttons' clicks; the views only render
+ *   by its layout.
- * and forward clicks.
+ * @property {boolean} pinned A dock tray kept open (`dock-pinned`).
+ * @property {boolean} pinnedTop The pinned tray drawn on top.
+ * @property {?('layout'|'accordion')} auto Why a layout closed the panel
+ *   (`layout-auto-collapsed`, `accordion-collapsed`), or null when the
+ *   person's own choice stands.
+ */
+
+/** A panel's state before its owner has said otherwise. */
+const BLANK = Object.freeze({
+  collapsed: false,
+  pinned: false,
+  pinnedTop: false,
+  auto: null,
+});
+
+/**
+ * Each panel's disclosure state, which its root (`vPanelState`) and its
+ * collapse, dock and pin buttons render. PanelChrome owns the panels: it and
+ * the layouts it runs publish here whenever a panel opens, closes or is
+ * pinned, and it connects the buttons' clicks; the views only render and
+ * forward clicks.
  */
 export const usePanelChromeStore = defineStore('gev-panel-chrome', () => {
   /**
-   * `{[panelId]: {collapsed, pinned}}`, frozen; a panel is absent until its
+   * `{[panelId]: PanelState}`, frozen; a panel is absent until its owner
-   * owner first presents it, and its buttons keep their markup until then.
+   * first presents it, and it keeps its markup's classes until then.
    */
   const panels = shallowRef(Object.freeze({}));
   /** @type {{handlers: PanelChromeHandlers}|null} */
@@ -44,17 +64,13 @@ export const usePanelChromeStore = defineStore('gev-panel-chrome', () => {
    * unchanged state is not republished.
    * @param {object} token
    * @param {string} panelId
-   * @param {{collapsed?: boolean, pinned?: boolean}} patch
+   * @param {Partial<PanelState>} patch
    */
   function publish(token, panelId, patch) {
     if (!owns(token) || !panelId) return;
     const prior = panels.value[panelId];
-    const next = { collapsed: false, pinned: false, ...prior, ...patch };
+    const next = { ...BLANK, ...prior, ...patch };
-    if (
+    if (prior && Object.keys(BLANK).every((key) => prior[key] === next[key]))
-      prior &&
-      prior.collapsed === next.collapsed &&
-      prior.pinned === next.pinned
-    )
       return;
     panels.value = Object.freeze({
       ...panels.value,

src/ui/views/CommandDockView.vue

@@ -1,6 +1,7 @@
 <script setup>
 import { storeToRefs } from 'pinia';
 import { msg, t } from '../../i18n/index.js';
+import { vPanelState } from '../rail/panelState.js';
 import UiButton from '../kit/UiButton.vue';
 import { vClassToggle } from '../rail/classToggle.js';
 import { useDisplayStore } from '../stores/display.js';
@@ -67,7 +68,7 @@ function selectMapSource(chip) {
   <div id="command-dock" class="ui-scroll" aria-label="Navigation, voice, and visual preset controls" data-i18n-aria-label>
   <template v-for="slot in dockOrder" :key="slot">
   <!-- Control panel -->
-  <div v-if="slot === 'control'" id="control-panel" class="panel-collapsible collapsed">
+  <div v-if="slot === 'control'" id="control-panel" v-panel-state="'control-panel'" class="panel-collapsible collapsed">
     <div class="panel-glow"></div>
     <div class="panel-inner">
       <button id="control-panel-toggle" class="panel-header dock-tray-toggle" type="button"
@@ -128,7 +129,7 @@ function selectMapSource(chip) {
   <VoiceControl v-else-if="slot === 'voice'" :key="voice.id" :view="voice" />
 
   <!-- Location bar -->
-  <div v-else-if="slot === 'location'" id="location-bar" class="panel-collapsible collapsed">
+  <div v-else-if="slot === 'location'" id="location-bar" v-panel-state="'location-bar'" class="panel-collapsible collapsed">
     <div class="panel-glow"></div>
     <div class="location-inner">
       <div class="location-toolbar">

src/ui/views/ContextView.vue

@@ -2,6 +2,7 @@
 import { computed } from 'vue';
 import { storeToRefs } from 'pinia';
 import { t } from '../../i18n/index.js';
+import { vPanelState } from '../rail/panelState.js';
 import PanelCollapseButton from '../rail/PanelCollapseButton.vue';
 import { vClassToggle } from '../rail/classToggle.js';
 import { useCockpitStore } from '../stores/cockpit.js';
@@ -28,7 +29,7 @@ const sceneRuntime = computed(() => scenePanel.value?.runtime ?? '');
 <template>
   <!-- Global Context is deliberately independent from the left layer accordion. -->
   <aside id="right-context-rail" class="ui-scroll" v-class-toggle="{ 'bhote-event-active': !!bhotePanel }">
-    <div id="weather-panel" class="panel-collapsible" data-panel-id="weather-panel" hidden>
+    <div id="weather-panel" v-panel-state="'weather-panel'" class="panel-collapsible" data-panel-id="weather-panel" hidden>
       <div class="panel-glow"></div>
       <div class="weather-panel-inner" data-rail-scroller>
         <div class="panel-header">
@@ -40,7 +41,7 @@ const sceneRuntime = computed(() => scenePanel.value?.runtime ?? '');
         <div id="weather-panel-body" class="ui-scroll" data-rail-scroller></div>
       </div>
     </div>
-    <div id="recent-imagery-panel" class="panel-collapsible" data-panel-id="recent-imagery-panel" hidden>
+    <div id="recent-imagery-panel" v-panel-state="'recent-imagery-panel'" class="panel-collapsible" data-panel-id="recent-imagery-panel" hidden>
       <div class="panel-glow"></div>
       <div class="recent-imagery-panel-inner" data-rail-scroller>
         <div class="panel-header">
@@ -52,7 +53,7 @@ const sceneRuntime = computed(() => scenePanel.value?.runtime ?? '');
         <div id="recent-imagery-panel-body" class="ui-scroll" data-rail-scroller></div>
       </div>
     </div>
-    <div id="global-context-panel" class="panel-collapsible collapsed" v-class-toggle="{ ...(ctx && { 'context-enabled': ctx.enabled }) }" :data-context-mode="ctx?.mode" data-panel-id="global-context-panel">
+    <div id="global-context-panel" v-panel-state="'global-context-panel'" class="panel-collapsible collapsed" v-class-toggle="{ ...(ctx && { 'context-enabled': ctx.enabled }) }" :data-context-mode="ctx?.mode" data-panel-id="global-context-panel">
       <div class="panel-glow"></div>
       <div class="global-context-panel-inner ui-scroll" data-rail-scroller>
         <div class="panel-header">

src/ui/views/LayerPanelsView.vue

@@ -1,6 +1,7 @@
 <script setup>
 import { storeToRefs } from 'pinia';
 import { t } from '../../i18n/index.js';
+import { vPanelState } from '../rail/panelState.js';
 import PanelCollapseButton from '../rail/PanelCollapseButton.vue';
 import { useSceneSharingStore } from '../stores/sceneSharing.js';
 import { useSceneStore } from '../stores/scenes.js';
@@ -37,7 +38,7 @@ async function importChosen(event) {
 <template>
   <div id="left-panel-stack" class="ui-scroll">
   <!-- Data Layer Toggle Panel -->
-  <div id="data-panel" class="panel-collapsible collapsed active" data-panel-id="data-panel">
+  <div id="data-panel" v-panel-state="'data-panel'" class="panel-collapsible collapsed active" data-panel-id="data-panel">
     <div class="panel-glow"></div>
     <div class="data-panel-inner">
       <div class="panel-header">
@@ -56,7 +57,7 @@ async function importChosen(event) {
   <StreetLevelPanel />
 
   <!-- Scene Director Panel -->
-  <div id="scene-panel" v-class-toggle="{ running: scene?.running, 'has-shots': scene?.hasShots }" class="panel-collapsible collapsed" data-panel-id="scene-panel">
+  <div id="scene-panel" v-panel-state="'scene-panel'" v-class-toggle="{ running: scene?.running, 'has-shots': scene?.hasShots }" class="panel-collapsible collapsed" data-panel-id="scene-panel">
     <div class="panel-glow"></div>
     <div class="scene-panel-inner ui-scroll">
       <div class="panel-header">

src/ui/views/panels/CctvPanel.vue

@@ -2,6 +2,7 @@
 import { storeToRefs } from 'pinia';
 import { computed } from 'vue';
 import { t } from '../../../i18n/index.js';
+import { vPanelState } from '../../rail/panelState.js';
 import PanelCollapseButton from '../../rail/PanelCollapseButton.vue';
 import CctvCalValue from '../../cctv/CctvCalValue.vue';
 import CctvPicker from '../../cctv/CctvPicker.vue';
@@ -27,7 +28,7 @@ const frameData = computed(() =>
 </script>
 
 <template>
-<div id="cctv-panel" class="panel-collapsible collapsed" data-panel-id="cctv-panel">
+<div id="cctv-panel" v-panel-state="'cctv-panel'" class="panel-collapsible collapsed" data-panel-id="cctv-panel">
   <div class="panel-glow"></div>
   <div class="cctv-panel-inner ui-scroll" data-rail-scroller>
     <div class="panel-header">

src/ui/views/panels/DisplayPanel.vue

@@ -2,6 +2,7 @@
 import { storeToRefs } from 'pinia';
 import { computed } from 'vue';
 import { t } from '../../../i18n/index.js';
+import { vPanelState } from '../../rail/panelState.js';
 import PanelCollapseButton from '../../rail/PanelCollapseButton.vue';
 import { vRangeValue } from '../../rail/rangeValue.js';
 import { useDisplayStore } from '../../stores/display.js';
@@ -43,7 +44,7 @@ const geoListed = computed(() => geoRows.value.length > 0);
 
 <template>
 <!-- Post-processing toggles (top-right) -->
-<div id="pp-toggles" class="panel-collapsible collapsed ui-scroll" data-panel-id="pp-toggles">
+<div id="pp-toggles" v-panel-state="'pp-toggles'" class="panel-collapsible collapsed ui-scroll" data-panel-id="pp-toggles">
   <div class="compact pp-header-row">
     <span data-i18n class="pp-header-label">DISPLAY</span>
     <span class="panel-divider" aria-hidden="true"></span>
@@ -123,7 +124,7 @@ const geoListed = computed(() => geoRows.value.length > 0);
     </div>
   </div>
   <!-- The one shared preset-parameter surface is inserted here at runtime. -->
-  <div id="param-slider-panel">
+  <div id="param-slider-panel" v-panel-state="'param-slider-panel'">
     <div class="param-panel-header">
       <span class="param-panel-title" data-i18n>PARAMETERS</span>
       <span class="param-panel-divider"></span>

src/ui/views/panels/RadioPanel.vue

@@ -2,6 +2,7 @@
 import { storeToRefs } from 'pinia';
 import { computed } from 'vue';
 import { t } from '../../../i18n/index.js';
+import { vPanelState } from '../../rail/panelState.js';
 import PanelCollapseButton from '../../rail/PanelCollapseButton.vue';
 import { vClassToggle } from '../../rail/classToggle.js';
 import { vFieldValue } from '../../rail/fieldValue.js';
@@ -29,7 +30,7 @@ const radioWords = {
 </script>
 
 <template>
-<section id="radio-panel" class="panel-collapsible collapsed" v-class-toggle="{ ...(radio && { 'radio-enabled': radio.enabled, 'lifecycle-uncertain': radio.uncertain }), ...(sdrConnected !== null && { 'sdr-connected': sdrConnected }) }" data-panel-id="radio-panel" aria-label="Internet radio and local SDR" data-i18n-aria-label>
+<section id="radio-panel" v-panel-state="'radio-panel'" class="panel-collapsible collapsed" v-class-toggle="{ ...(radio && { 'radio-enabled': radio.enabled, 'lifecycle-uncertain': radio.uncertain }), ...(sdrConnected !== null && { 'sdr-connected': sdrConnected }) }" data-panel-id="radio-panel" aria-label="Internet radio and local SDR" data-i18n-aria-label>
   <div class="radio-panel-inner ui-scroll">
     <div class="panel-header">
       <span class="panel-title" data-i18n>RADIO</span>

src/ui/views/panels/StreetLevelPanel.vue

@@ -2,6 +2,7 @@
 import { storeToRefs } from 'pinia';
 import { computed, shallowRef, watch } from 'vue';
 import { t } from '../../../i18n/index.js';
+import { vPanelState } from '../../rail/panelState.js';
 import PanelCollapseButton from '../../rail/PanelCollapseButton.vue';
 import RailChips from '../../rail/RailChips.vue';
 import { useStreetLevelStore } from '../../stores/streetLevel.js';
@@ -101,7 +102,7 @@ const vThumb = { mounted: placeThumb, updated: placeThumb };
 </script>
 
 <template>
-<div id="street-level-panel" class="panel-collapsible collapsed" data-panel-id="street-level-panel" :data-sl-enabled="view ? String(view.enabled) : undefined">
+<div id="street-level-panel" v-panel-state="'street-level-panel'" class="panel-collapsible collapsed" data-panel-id="street-level-panel" :data-sl-enabled="view ? String(view.enabled) : undefined">
   <div class="panel-glow"></div>
   <div class="street-level-panel-inner ui-scroll" data-rail-scroller>
     <div class="panel-header">

src/ui/visualSettings.js

@@ -445,8 +445,7 @@ export class VisualSettings {
       return;
     }
     if (!this._cockpitDisclosureOpen?.('display')) return;
-    this._sliderPanel.classList.remove('collapsed');
+    this._presentPanel(this._sliderPanel, { collapsed: false });
-    this._syncPanelCollapseButton(this._sliderPanel);
     this._lifetime.frame(() =>
       this._lifetime.frame(() => {
         this._sliderPanel?.scrollIntoView?.({ block: 'nearest' });
@@ -1434,8 +1433,7 @@ export class VisualSettings {
   _revealStyleParameters() {
     if (!this._sliderPanel?.classList.contains('active')) return;
     if (this._cockpitDisplayPortalActive) return;
-    this._sliderPanel.classList.remove('collapsed');
+    this._presentPanel(this._sliderPanel, { collapsed: false });
-    this._syncPanelCollapseButton(this._sliderPanel);
     this.setPanelCollapsed('pp-toggles', false, { explicit: true });
     this._lifetime.frame(() =>
       this._lifetime.frame(() => {

src/voice/gevActions.js

@@ -817,7 +817,17 @@ export function createGevActionRunner({
           ...(!applied ? { error: say } : {}),
         };
       }
-      setPanelOpen(styleManager, panelId, open);
+      if (!setPanelOpen(styleManager, panelId, open)) {
+        const say = 'There is no panel to open here.';
+        return {
+          ok: false,
+          action: 'set_panel_open',
+          panelId,
+          open,
+          say,
+          error: say,
+        };
+      }
       return { ok: true, action: 'set_panel_open', panelId, open };
     }
 
@@ -3143,13 +3153,14 @@ function normalizeAircraftClassFilter(value) {
   return raw.replace(/[\s-]+/g, '') === TR3B_CLASS ? TR3B_CLASS : raw;
 }
 
+/**
+ * @returns {boolean} Whether a shell took the change: its panel chrome owns
+ *   panel state, so without one there is no panel to open.
+ */
 function setPanelOpen(styleManager, panelId, open) {
-  if (styleManager && typeof styleManager.setPanelCollapsed === 'function') {
+  if (typeof styleManager?.setPanelCollapsed !== 'function') return false;
-    styleManager.setPanelCollapsed(panelId, !open, { explicit: true });
+  styleManager.setPanelCollapsed(panelId, !open, { explicit: true });
-  } else {
+  return true;
-    const panel = document.getElementById(panelId);
-    if (panel) panel.classList.toggle('collapsed', !open);
-  }
 }
 
 function normalizeContextMode(value) {