diff --git a/backend/src/panic.h b/backend/src/panic.h
new file mode 100644
index 0000000..d80ec2f
--- /dev/null
+++ b/backend/src/panic.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define PANIC(...)                                                             \
+    (fputs("\x1b[1;31mpanic\x1b[97m: ", stderr), fprintf(stderr, __VA_ARGS__), \
+        fprintf(stderr, "\x1b[0m\n\tin %s:%d\n\tat %s:%d\n", __func__,         \
+            __LINE__, __FILE__, __LINE__),                                     \
+        exit(1), 0)
+
+__attribute__((unused)) static inline void ___include_user(void)
+{
+    PANIC("");
+}
diff --git a/backend/src/session.h b/backend/src/session.h
new file mode 100644
index 0000000..279439a
--- /dev/null
+++ b/backend/src/session.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <stdint.h>
+#include "collection.h"
+
+typedef struct {
+    int64_t user_id;
+} Session;
+
+DEFINE_VEC(Session, SessionVec, session_vec, 16)