diff --git a/src/app/admin/import/furni/nitro-editor-dialog.tsx b/src/app/admin/import/furni/nitro-editor-dialog.tsx
index db5de15a64..719562de38 100644
--- a/src/app/admin/import/furni/nitro-editor-dialog.tsx
+++ b/src/app/admin/import/furni/nitro-editor-dialog.tsx
@@ -39,28 +39,56 @@ interface NitroEditorDialogProps {
 	onOpenChange: (open: boolean) => void;
 }
 
-// Keep these helpers on `any` — Next's build-time checker has repeatedly
-// disagreed with `tsc` on stricter JSON typings for this editor.
-// biome-ignore lint/suspicious/noExplicitAny: metadata tree is untyped JSON
-function updateNested(obj: any, path: string, value: unknown): any {
-	const clone = JSON.parse(JSON.stringify(obj));
+interface NitroVisualization {
+	size?: number;
+	layers?: Record<string, { z?: number; alpha?: number; ink?: string }>;
+	colors?: Record<string, Record<string, { color: number }>>;
+	animations?: Record<string, unknown>;
+}
+
+// The .nitro metadata is untyped JSON from disk; typed only for the fields the
+// editor reads/writes, with an index signature so the generic path helpers can
+// traverse arbitrary nested keys.
+interface NitroMetadata {
+	visualizationType?: string;
+	logicType?: string;
+	logic?: {
+		model?: {
+			dimensions?: { x: number; y: number; z: number };
+			directions?: number[];
+		};
+	};
+	visualizations?: NitroVisualization[];
+	[key: string]: unknown;
+}
+
+type JsonObject = Record<string, unknown>;
+
+function updateNested<T extends JsonObject>(
+	obj: T,
+	path: string,
+	value: unknown,
+): T {
+	const clone: T = JSON.parse(JSON.stringify(obj));
 	const keys = path.split(".");
-	let current = clone;
+	let current: JsonObject = clone;
 	for (let i = 0; i < keys.length - 1; i++) {
-		if (!current[keys[i]]) current[keys[i]] = {};
-		current = current[keys[i]];
+		const next = current[keys[i]];
+		if (!next || typeof next !== "object" || Array.isArray(next)) {
+			current[keys[i]] = {};
+		}
+		current = current[keys[i]] as JsonObject;
 	}
 	current[keys[keys.length - 1]] = value;
 	return clone;
 }
 
-// biome-ignore lint/suspicious/noExplicitAny: metadata tree is untyped JSON
-function getNested(obj: any, path: string, fallback?: unknown): any {
+function getNested(obj: unknown, path: string, fallback?: unknown): unknown {
 	const keys = path.split(".");
-	let current = obj;
+	let current: unknown = obj;
 	for (const key of keys) {
 		if (current == null || typeof current !== "object") return fallback;
-		current = current[key];
+		current = (current as JsonObject)[key];
 	}
 	return current ?? fallback;
 }
@@ -99,10 +127,9 @@ export function NitroEditorDialog({
 	open,
 	onOpenChange,
 }: NitroEditorDialogProps) {
-	// biome-ignore lint/suspicious/noExplicitAny: explicitly chosen here, see surrounding code
-	const [metadata, setMetadata] = useState<any>(null);
-	// biome-ignore lint/suspicious/noExplicitAny: explicitly chosen here, see surrounding code
-	const [originalMetadata, setOriginalMetadata] = useState<any>(null);
+	const [metadata, setMetadata] = useState<NitroMetadata | null>(null);
+	const [originalMetadata, setOriginalMetadata] =
+		useState<NitroMetadata | null>(null);
 	const [jsonText, setJsonText] = useState("");
 	const [loading, setLoading] = useState(false);
 	const [saving, setSaving] = useState(false);
@@ -120,10 +147,9 @@ export function NitroEditorDialog({
 	const [jsonError, setJsonError] = useState<string | null>(null);
 
 	const patchMeta = (path: string, value: unknown) => {
-		// Explicit any avoids noImplicitAny on updater params and dodges
-		// Next build's stricter JSON inference that disagreed with tsc.
-		// biome-ignore lint/suspicious/noExplicitAny: metadata tree is untyped JSON
-		setMetadata((prev: any) => updateNested(prev, path, value));
+		setMetadata((prev) =>
+			prev == null ? prev : updateNested(prev, path, value),
+		);
 	};
 
 	const fetchMetadata = useCallback(async () => {
@@ -258,12 +284,9 @@ export function NitroEditorDialog({
 	};
 
 	// Get visualization with size=64 for layer/color editing
-	// biome-ignore lint/suspicious/noExplicitAny: explicitly chosen here, see surrounding code
-	const viz64 = metadata?.visualizations?.find((v: any) => v.size === 64);
+	const viz64 = metadata?.visualizations?.find((v) => v.size === 64);
 	const viz64Index =
-		metadata?.visualizations?.findIndex(
-			(v: { size: number }) => v.size === 64,
-		) ?? -1;
+		metadata?.visualizations?.findIndex((v) => v.size === 64) ?? -1;
 
 	const layerCount = viz64?.layers ? Object.keys(viz64.layers).length : 0;
 	const colorCount = viz64?.colors ? Object.keys(viz64.colors).length : 0;