[Init] Initial commit - NetMesh terminal manager

application/state/appearanceChromeStore.ts

@@ -0,0 +1,68 @@
+import { useSyncExternalStore } from 'react';
+
+type Listener = () => void;
+
+export type AppearanceChromeSnapshot = {
+  accentMode: 'theme' | 'custom';
+  customAccent: string;
+};
+
+const DEFAULT_SNAPSHOT: AppearanceChromeSnapshot = Object.freeze({
+  accentMode: 'theme',
+  customAccent: '',
+});
+
+/**
+ * External store for app accent chrome so Terminal leaves can apply custom
+ * accent without TerminalLayer rebuilding on every color-picker drag tick.
+ */
+class AppearanceChromeStore {
+  private snapshot: AppearanceChromeSnapshot = DEFAULT_SNAPSHOT;
+  private listeners = new Set<Listener>();
+
+  getSnapshot = (): AppearanceChromeSnapshot => this.snapshot;
+
+  subscribe = (listener: Listener): (() => void) => {
+    this.listeners.add(listener);
+    return () => {
+      this.listeners.delete(listener);
+    };
+  };
+
+  setSnapshot(next: AppearanceChromeSnapshot): void {
+    if (
+      this.snapshot.accentMode === next.accentMode
+      && this.snapshot.customAccent === next.customAccent
+    ) {
+      return;
+    }
+    this.snapshot = next;
+    for (const listener of this.listeners) {
+      listener();
+    }
+  }
+}
+
+export const appearanceChromeStore = new AppearanceChromeStore();
+
+export function publishAppearanceChromeSnapshot(
+  snapshot: AppearanceChromeSnapshot,
+): void {
+  appearanceChromeStore.setSnapshot(snapshot);
+}
+
+export function getAppearanceChromeSnapshot(): AppearanceChromeSnapshot {
+  return appearanceChromeStore.getSnapshot();
+}
+
+export function subscribeAppearanceChrome(listener: Listener): () => void {
+  return appearanceChromeStore.subscribe(listener);
+}
+
+export function useAppearanceChromeStore(): AppearanceChromeSnapshot {
+  return useSyncExternalStore(
+    subscribeAppearanceChrome,
+    getAppearanceChromeSnapshot,
+    getAppearanceChromeSnapshot,
+  );
+}