fix(frontend): resolve 26 svelte-check type errors

- add @types/node for hooks.server process/env types
- fix katex auto-render import path (contrib/auto-render)
- declare global Web Bluetooth API types in ble-deployer
- guard simApi null in CircuitEditor autosave interval
- default-type imports for CodeEditor/CircuitEditor
- make lesson slug getter non-nullable
- add expected_flowchart to LessonContent type
- key lesson workspace by slug; drop phantom onReset prop
- guard CodeTab render when lesson data is null

frontend/package-lock.json

@@ -21,6 +21,7 @@
         "@sveltejs/kit": "^2.0.0",
         "@sveltejs/vite-plugin-svelte": "^5.0.0",
         "@types/katex": "^0.16.7",
+        "@types/node": "^26.2.0",
         "svelte": "^5.0.0",
         "svelte-check": "^4.0.0",
         "typescript": "^5.0.0",
@@ -1287,6 +1288,16 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/node": {
+      "version": "26.2.0",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-26.2.0.tgz",
+      "integrity": "sha512-5IviulTZeRNp2vAJ514cc/HUlY5nZ9fCbq9DMyC52BrhFZACo3nI0R7qBxhQmo/d27NFe96ur/b7Wwxklda+kg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "undici-types": "~8.3.0"
+      }
+    },
     "node_modules/@types/resolve": {
       "version": "1.20.2",
       "resolved": "https://registry.npmjs.org/@types/resolve/-/resolve-1.20.2.tgz",
@@ -2279,6 +2290,13 @@
         "node": ">=14.17"
       }
     },
+    "node_modules/undici-types": {
+      "version": "8.3.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-8.3.0.tgz",
+      "integrity": "sha512-j375ScV60dom+YkPFIfTLcOiPxkN/buHz5GobjLhixFuANaNs3C9l4GmrWqejgXWJ7BbJcFYpTEUkS1Ge8bpZQ==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/vite": {
       "version": "6.4.3",
       "resolved": "https://registry.npmjs.org/vite/-/vite-6.4.3.tgz",

frontend/package.json

@@ -15,6 +15,7 @@
     "@sveltejs/kit": "^2.0.0",
     "@sveltejs/vite-plugin-svelte": "^5.0.0",
     "@types/katex": "^0.16.7",
+    "@types/node": "^26.2.0",
     "svelte": "^5.0.0",
     "svelte-check": "^4.0.0",
     "typescript": "^5.0.0",

frontend/src/lib/actions/renderMath.ts

@@ -5,7 +5,7 @@ export async function autoRenderMath(node: HTMLElement) {
 	if (!browser) return;
 
 	try {
-		const renderMathInElement = (await import('katex/dist/contrib/auto-render')).default;
+		const renderMathInElement = (await import('katex/contrib/auto-render')).default;
 		await import('katex/dist/katex.min.css');
 
 		// 1. First, handle the standard delimiters

frontend/src/lib/components/CircuitEditor.svelte

@@ -127,6 +127,7 @@
 	$effect(() => {
 		if (simApi && ready && storageKey) {
 			const interval = setInterval(() => {
+				if (!simApi) return;
 				const currentText = simApi.exportCircuit();
 				const saved = localStorage.getItem(storageKey);
 				if (currentText && currentText !== saved && currentText.trim().length > 10) {

frontend/src/lib/services/ble-deployer.ts

@@ -8,6 +8,98 @@ import {
 	type DeployProgress, type BLEACKResponse
 } from '$types/deployer';
 
+/* Ambient declarations for Web Bluetooth API (not in TS lib.dom.d.ts). */
+/* Minimal subset needed by BLEHardwareDeployer.                        */
+/* Wrapped in declare global because the file is a module (has imports) */
+/* and we need these types to be globally visible.                      */
+declare global {
+	interface Navigator {
+		readonly bluetooth: Bluetooth;
+	}
+
+	interface Bluetooth {
+		requestDevice(options: RequestDeviceOptions): Promise<BluetoothDevice>;
+	}
+
+	interface RequestDeviceOptions {
+		filters?: BluetoothLEScanFilter[];
+		optionalServices?: BluetoothServiceUUID[];
+		acceptAllDevices?: boolean;
+	}
+
+	interface BluetoothLEScanFilter {
+		name?: string;
+		namePrefix?: string;
+		services?: BluetoothServiceUUID[];
+		manufacturerId?: number;
+	}
+
+	type BluetoothServiceUUID = string | number;
+
+	interface BluetoothDevice {
+		readonly id: string;
+		readonly name?: string;
+		readonly gatt?: BluetoothRemoteGATTServer;
+		addEventListener(
+			type: 'gattserverdisconnected',
+			listener: (this: BluetoothDevice, ev: Event) => void
+		): void;
+		removeEventListener(
+			type: 'gattserverdisconnected',
+			listener: (this: BluetoothDevice, ev: Event) => void
+		): void;
+	}
+
+	interface BluetoothRemoteGATTServer {
+		readonly connected: boolean;
+		readonly device: BluetoothDevice;
+		readonly mtu: number;
+		connect(): Promise<BluetoothRemoteGATTServer>;
+		disconnect(): void;
+		requestMTU(size: number): Promise<BluetoothRemoteGATTServer>;
+		getPrimaryService(service: BluetoothServiceUUID): Promise<BluetoothRemoteGATTService>;
+		getPrimaryServices(service?: BluetoothServiceUUID): Promise<BluetoothRemoteGATTService[]>;
+	}
+
+	interface BluetoothRemoteGATTService {
+		readonly device: BluetoothDevice;
+		readonly uuid: string;
+		readonly isPrimary: boolean;
+		getCharacteristic(characteristic: BluetoothServiceUUID): Promise<BluetoothRemoteGATTCharacteristic>;
+		getCharacteristics(characteristic?: BluetoothServiceUUID): Promise<BluetoothRemoteGATTCharacteristic[]>;
+	}
+
+	interface BluetoothRemoteGATTCharacteristic extends EventTarget {
+		readonly service: BluetoothRemoteGATTService;
+		readonly uuid: string;
+		readonly properties: BluetoothCharacteristicProperties;
+		readonly value: DataView | null;
+		readValue(): Promise<DataView>;
+		writeValue(value: BufferSource): Promise<void>;
+		writeValueWithResponse(value: BufferSource): Promise<void>;
+		writeValueWithoutResponse(value: BufferSource): Promise<void>;
+		startNotifications(): Promise<BluetoothRemoteGATTCharacteristic>;
+		stopNotifications(): Promise<BluetoothRemoteGATTCharacteristic>;
+		addEventListener(
+			type: 'characteristicvaluechanged',
+			listener: (this: BluetoothRemoteGATTCharacteristic, ev: Event) => void
+		): void;
+		removeEventListener(
+			type: 'characteristicvaluechanged',
+			listener: (this: BluetoothRemoteGATTCharacteristic, ev: Event) => void
+		): void;
+	}
+
+	interface BluetoothCharacteristicProperties {
+		readonly read: boolean;
+		readonly write: boolean;
+		readonly notify: boolean;
+		readonly indicate: boolean;
+		readonly writeWithoutResponse: boolean;
+		readonly broadcast: boolean;
+	}
+}
+
 let _ackNotificationCount = 0;
 function logAck(tag: string, msg: string) {
 	console.log(`[BLE-ACK#${++_ackNotificationCount}] ${tag}: ${msg}`);

frontend/src/lib/types/lesson.ts

@@ -22,6 +22,7 @@ export interface LessonContent {
 	initial_python: string;
 	initial_circuit: string;
 	initial_flowchart?: any;
+	expected_flowchart?: string;
 	initial_quiz: string;
 	initial_code_arduino: string;
 	velxio_circuit: string;

frontend/src/routes/lesson/[slug]/+page.svelte

@@ -186,7 +186,7 @@ import QuizQuestionView from './QuizQuestionView.svelte';
 </svelte:head>
 
 {#if pageData.lesson}
-	{#key pageData.lesson.filename}
+	{#key mgr.slug}
 		<div class="lesson-layout" class:single-col={float.floating || mgr.isMobile}>
 			<!-- svelte-ignore a11y_no_static_element_interactions -->
 			<div class="lesson-content" bind:this={contentEl} use:noSelect use:renderMath
@@ -326,7 +326,6 @@ import QuizQuestionView from './QuizQuestionView.svelte';
 								storageKey={mgr.flowchartStorageKey}
 								initialData={mgr.data?.initial_flowchart}
 								onRun={mgr.handleRun.bind(mgr)}
-								onReset={mgr.handleReset.bind(mgr)}
 								compiling={mgr.compiling}
 							/>
 						</div>
@@ -343,7 +342,7 @@ import QuizQuestionView from './QuizQuestionView.svelte';
 						</div>
 					{/if}
 
-					{#if !mgr.data?.active_tabs?.length || mgr.data.active_tabs.includes('c') || mgr.data.active_tabs.includes('python')}
+					{#if mgr.data && (!mgr.data.active_tabs?.length || mgr.data.active_tabs.includes('c') || mgr.data.active_tabs.includes('python'))}
 						<div class="tab-panel" class:tab-hidden={mgr.activeTab !== 'editor'}>
 							<CodeTab
 								data={mgr.data}

frontend/src/routes/lesson/[slug]/lesson.svelte.ts

@@ -11,8 +11,8 @@ import { evaluateCircuitSubmission, processLanguageEvaluation } from '$services/
 import { getVelxioState, initVelxioBridge } from '$services/velxio-manager';
 import { VelxioBridge } from '$services/velxio-bridge';
 import type { LessonContent } from '$types/lesson';
-import type { CodeEditor } from '$components/CodeEditor.svelte';
-import type { CircuitEditor } from '$components/CircuitEditor.svelte';
+import type CodeEditor from '$components/CodeEditor.svelte';
+import type CircuitEditor from '$components/CircuitEditor.svelte';
 import type { DeployState } from '$types/deployer';
 import type { QuizQuestion, QuizAnswer } from '$types/quiz';
 import {
@@ -71,7 +71,7 @@ export class LessonManager {
 	circuitEditor = $state<CircuitEditor | null>(null);
 	flowchartTab = $state<any>(null);
 
-	get slug() { return get(page).params.slug; }
+	get slug(): string { return get(page).params.slug ?? ''; }
 	
 	isVelxio = $derived(this.data?.active_tabs?.includes('velxio') ?? false);
 	isFlowchart = $derived(this.data?.active_tabs?.includes('flowchart') ?? false);
@@ -379,7 +379,7 @@ export class LessonManager {
 		this.activeTab = 'output';
 		try {
 			const circuitText = this.circuitEditor.getCircuitText();
-			const res = evaluateCircuitSubmission(simApi, circuitText, this.isHybrid, this.data, () => this.checkAllPassed());
+			const res = evaluateCircuitSubmission(simApi, circuitText, this.isHybrid ?? false, this.data, () => this.checkAllPassed());
 			if (res.error) {
 				Object.assign(this.circuitOut, { error: res.error, success: false, loading: false });
 				return;