editor external changes sync

frontend/src/lib/components/Editor.svelte

@@ -1921,6 +1921,25 @@
 		})
 	})
 
+	// External `code` prop changes should flow into the Monaco editor. The
+	// `untrack` block reads/writes Monaco without subscribing — only the
+	// prop read above is tracked — so the editor's own change handler
+	// (`updateCode`) re-running with the same value short-circuits and we
+	// don't loop.
+	$effect(() => {
+		const next = code ?? ''
+		const ed = editor
+		if (!ed) return
+		untrack(() => {
+			if (ed.getValue() === next) return
+			const model = ed.getModel()
+			if (!model) return
+			ed.pushUndoStop()
+			ed.executeEdits('external', [{ range: model.getFullModelRange(), text: next }])
+			ed.pushUndoStop()
+		})
+	})
+
 	let isTsWorkerInitialized = resource([() => lang, () => initialized], async () => {
 		if (lang !== 'typescript' || !initialized) return false
 		// Use the stable model URI (computed once at mount), not filePath which changes on rename