feat(app): load xterm search addon + surface→addon registry

app/src/TerminalView.tsx

@@ -1,7 +1,9 @@
 import { useEffect, useRef } from "react";
 import { Terminal } from "@xterm/xterm";
 import { WebglAddon } from "@xterm/addon-webgl";
+import { SearchAddon } from "@xterm/addon-search";
 import { attachSurface, detachSurface, sendInput, resizeSurface } from "./socketBridge";
+import { registerSearch, unregisterSearch } from "./searchRegistry";
 
 const decoder = new TextDecoder();
 const encoder = new TextEncoder();
@@ -11,7 +13,7 @@ export function TerminalView({ surfaceId }: { surfaceId: string }) {
 
   useEffect(() => {
     if (!ref.current) return;
-    const term = new Terminal({ fontFamily: "'JetBrains Mono Variable', 'JetBrains Mono', monospace", fontSize: 13, convertEol: false });
+    const term = new Terminal({ fontFamily: "'JetBrains Mono Variable', 'JetBrains Mono', monospace", fontSize: 13, convertEol: false, scrollback: 10000 });
     try {
       term.loadAddon(new WebglAddon());
     } catch {
@@ -19,6 +21,10 @@ export function TerminalView({ surfaceId }: { surfaceId: string }) {
     }
     term.open(ref.current);
 
+    const search = new SearchAddon();
+    term.loadAddon(search);
+    registerSearch(surfaceId, search);
+
     // Input → daemon.
     const inputDisposable = term.onData((data) => {
       void sendInput(surfaceId, encoder.encode(data));
@@ -42,6 +48,7 @@ export function TerminalView({ surfaceId }: { surfaceId: string }) {
       disposed = true;
       inputDisposable.dispose();
       void detachSurface(surfaceId);
+      unregisterSearch(surfaceId);
       term.dispose();
     };
   }, [surfaceId]);

app/src/searchRegistry.ts

@@ -0,0 +1,17 @@
+import type { SearchAddon } from "@xterm/addon-search";
+
+/** Maps a surfaceId to its terminal's SearchAddon so the search bar can reach
+ * the focused panel without prop-drilling through the layout tree. */
+const registry = new Map<string, SearchAddon>();
+
+export function registerSearch(surfaceId: string, addon: SearchAddon): void {
+  registry.set(surfaceId, addon);
+}
+
+export function unregisterSearch(surfaceId: string): void {
+  registry.delete(surfaceId);
+}
+
+export function getSearch(surfaceId: string): SearchAddon | undefined {
+  return registry.get(surfaceId);
+}