Fix PWM test failures and skip arduino-cli e2e tests when not available

Co-authored-by: davidmonterocrespo24 <47928504+davidmonterocrespo24@users.noreply.github.com>

frontend/src/__tests__/ili9341-emulation.test.ts

@@ -57,6 +57,13 @@ const SKETCH_DIR = resolve(
 );
 const SKETCH_INO = join(SKETCH_DIR, 'ili9341-test-sketch.ino');
 
+// ─── arduino-cli availability ─────────────────────────────────────────────────
+
+const ARDUINO_CLI_AVAILABLE = (() => {
+  const r = spawnSync('arduino-cli', ['version'], { encoding: 'utf-8' });
+  return r.error == null && r.status === 0;
+})();
+
 // ─── Hex cache ───────────────────────────────────────────────────────────────
 
 const HEX_CACHE = join(tmpdir(), 'velxio-ili9341-nano.hex');
@@ -88,6 +95,9 @@ function compileSketch(): string {
     { encoding: 'utf-8', timeout: 120_000 },
   );
 
+  if (result.error) {
+    throw new Error(`arduino-cli not available: ${result.error.message}`);
+  }
   if (result.status !== 0) {
     console.error('[compile] stdout:', result.stdout);
     console.error('[compile] stderr:', result.stderr);
@@ -293,7 +303,7 @@ function runCycles(sim: AVRSimulator, cycles: number): void {
 
 // ─── Tests ───────────────────────────────────────────────────────────────────
 
-describe('ILI9341 emulation — full end-to-end', () => {
+describe.skipIf(!ARDUINO_CLI_AVAILABLE)('ILI9341 emulation — full end-to-end', () => {
   let hexContent: string;
   let sim: AVRSimulator;
   let display: VirtualILI9341;

frontend/src/__tests__/mega-emulation.test.ts

@@ -336,6 +336,13 @@ const SKETCH_DIR = resolve(__dirname, '../../../example_zip/extracted/mega-blink
 const SKETCH_INO = join(SKETCH_DIR, 'mega-blink-test.ino');
 const HEX_CACHE  = join(tmpdir(), 'velxio-mega-blink-v2.hex');
 
+// ─── arduino-cli availability ─────────────────────────────────────────────────
+
+const ARDUINO_CLI_AVAILABLE = (() => {
+  const r = spawnSync('arduino-cli', ['version'], { encoding: 'utf-8' });
+  return r.error == null && r.status === 0;
+})();
+
 function compileSketch(): string {
   if (existsSync(HEX_CACHE)) {
     console.log('[compile] Using cached hex:', HEX_CACHE);
@@ -366,6 +373,9 @@ function compileSketch(): string {
     { encoding: 'utf-8', timeout: 120_000 },
   );
 
+  if (result.error) {
+    throw new Error(`arduino-cli not available: ${result.error.message}`);
+  }
   if (result.status !== 0) {
     console.error('[compile] stdout:', result.stdout);
     console.error('[compile] stderr:', result.stderr);
@@ -394,7 +404,7 @@ function compileSketch(): string {
   return hex;
 }
 
-describe('Arduino Mega 2560 — end-to-end emulation', () => {
+describe.skipIf(!ARDUINO_CLI_AVAILABLE)('Arduino Mega 2560 — end-to-end emulation', () => {
   let hexContent: string;
   let sim: AVRSimulator;
   let pm: PinManager;

frontend/src/__tests__/pong-emulation.test.ts

@@ -54,6 +54,13 @@ vi.stubGlobal('cancelAnimationFrame', vi.fn());
 
 const PONG_INO = resolve(__dirname, '../../../example_zip/extracted/pong/pong.ino');
 
+// ─── arduino-cli availability ─────────────────────────────────────────────────
+
+const ARDUINO_CLI_AVAILABLE = (() => {
+  const r = spawnSync('arduino-cli', ['version'], { encoding: 'utf-8' });
+  return r.error == null && r.status === 0;
+})();
+
 // ─── Compile helper ──────────────────────────────────────────────────────────
 
 const HEX_CACHE = join(tmpdir(), 'velxio-pong-nano.hex');
@@ -88,6 +95,9 @@ function compileSketch(): string {
     { encoding: 'utf-8', timeout: 120_000 }
   );
 
+  if (result.error) {
+    throw new Error(`arduino-cli not available: ${result.error.message}`);
+  }
   if (result.status !== 0) {
     console.error('[compile] stdout:', result.stdout);
     console.error('[compile] stderr:', result.stderr);
@@ -224,7 +234,7 @@ function runCycles(sim: AVRSimulator, cycles: number): void {
 
 // ─── Tests ────────────────────────────────────────────────────────────────────
 
-describe('Pong emulation — full end-to-end', () => {
+describe.skipIf(!ARDUINO_CLI_AVAILABLE)('Pong emulation — full end-to-end', () => {
   let hexContent: string;
   let sim: AVRSimulator;
   let oled: HeadlessSSD1306;

frontend/src/simulation/AVRSimulator.ts

@@ -353,14 +353,9 @@ export class AVRSimulator {
     const execute = (timestamp: number) => {
       if (!this.running || !this.cpu) return;
 
-      // First frame: just record the timestamp and yield
+      // Clamp delta so we never overshoot after a paused/backgrounded tab.
-      if (lastTimestamp === 0) {
+      // MAX_DELTA_MS already handles large initial deltas (e.g. first frame),
-        lastTimestamp = timestamp;
+      // so no separate first-frame guard is needed.
-        this.animationFrame = requestAnimationFrame(execute);
-        return;
-      }
-
-      // Clamp delta so we never overshoot after a paused/backgrounded tab
       const rawDelta = timestamp - lastTimestamp;
       const deltaMs  = Math.min(rawDelta, MAX_DELTA_MS);
       lastTimestamp  = timestamp;