diff --git a/frontend/src/lib/stores/playground.test.ts b/frontend/src/lib/stores/playground.test.ts
new file mode 100644
index 0000000..85279ac
--- /dev/null
+++ b/frontend/src/lib/stores/playground.test.ts
@@ -0,0 +1,55 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { get } from 'svelte/store';
+import { playgroundStore } from './playground';
+
+describe('playgroundStore stdinQueue', () => {
+	beforeEach(() => {
+		playgroundStore.reset();
+		playgroundStore.clearConsole();
+	});
+
+	it('enqueueStdin menambah baris ke antrean', () => {
+		playgroundStore.enqueueStdin('Budi');
+		playgroundStore.enqueueStdin('17');
+		const state = get(playgroundStore);
+		expect(state.stdinQueue).toEqual(['Budi', '17']);
+	});
+
+	it('enqueueStdin mengabaikan baris kosong', () => {
+		playgroundStore.enqueueStdin('');
+		playgroundStore.enqueueStdin('   ');
+		const state = get(playgroundStore);
+		expect(state.stdinQueue).toEqual([]);
+	});
+
+	it('consumeStdin mengembalikan seluruh antrean + draft, digabung dengan newline, lalu mengosongkan', () => {
+		playgroundStore.enqueueStdin('Budi');
+		playgroundStore.enqueueStdin('17');
+		playgroundStore.setConsoleInput('draft yang belum dikirim');
+		const stdin = playgroundStore.consumeStdin();
+		expect(stdin).toBe('Budi\n17\ndraft yang belum dikirim');
+		const state = get(playgroundStore);
+		expect(state.stdinQueue).toEqual([]);
+		expect(state.consoleInput).toBe('');
+	});
+
+	it('consumeStdin mengembalikan string kosong jika tidak ada baris maupun draft', () => {
+		const stdin = playgroundStore.consumeStdin();
+		expect(stdin).toBe('');
+	});
+
+	it('consumeStdin menambah baris baru di akhir masing-masing baris', () => {
+		playgroundStore.enqueueStdin('Budi');
+		const stdin = playgroundStore.consumeStdin();
+		expect(stdin).toBe('Budi\n');
+	});
+
+	it('clearStdinQueue mengosongkan antrean tanpa menyentuh consoleInput', () => {
+		playgroundStore.enqueueStdin('Budi');
+		playgroundStore.setConsoleInput('draft');
+		playgroundStore.clearStdinQueue();
+		const state = get(playgroundStore);
+		expect(state.stdinQueue).toEqual([]);
+		expect(state.consoleInput).toBe('draft');
+	});
+});
diff --git a/frontend/src/lib/stores/playground.ts b/frontend/src/lib/stores/playground.ts
index 29b1fce..3a83ef0 100644
--- a/frontend/src/lib/stores/playground.ts
+++ b/frontend/src/lib/stores/playground.ts
@@ -29,6 +29,7 @@ interface PlaygroundState {
 	activeFileId: string;
 	consoleHistory: ConsoleLine[];
 	consoleInput: string;
+	stdinQueue: string[];
 	consoleVisible: boolean;
 	running: boolean;
 }
@@ -86,6 +87,7 @@ function initialState(): PlaygroundState {
 		activeFileId: files[0]?.id ?? '',
 		consoleHistory: [],
 		consoleInput: '',
+		stdinQueue: [],
 		consoleVisible: true,
 		running: false
 	};
@@ -169,6 +171,25 @@ function createPlaygroundStore() {
 			update((s) => ({ ...s, consoleInput: text }));
 		},
 
+		enqueueStdin: (text: string) => {
+			const trimmed = text.trim();
+			if (!trimmed) return;
+			update((s) => ({ ...s, stdinQueue: [...s.stdinQueue, trimmed] }));
+		},
+
+		consumeStdin: (): string => {
+			let stdin = '';
+			update((s) => {
+				stdin = s.stdinQueue.map((line) => line + '\n').join('') + s.consoleInput;
+				return { ...s, stdinQueue: [], consoleInput: '' };
+			});
+			return stdin;
+		},
+
+		clearStdinQueue: () => {
+			update((s) => ({ ...s, stdinQueue: [] }));
+		},
+
 		toggleConsole: () => {
 			update((s) => ({ ...s, consoleVisible: !s.consoleVisible }));
 		},