feat: add environment check helper

check_env.py

@@ -0,0 +1,54 @@
+```py
+"""
+Simple helper to verify that environment variables required for
+Kalshi starter code are present.
+
+Usage:
+    python check_env.py
+"""
+
+import os
+import textwrap
+
+
+REQUIRED_VARS = [
+    "KALSHI_API_KEY",
+    "KALSHI_API_SECRET",
+    "KALSHI_ENV",  # e.g. "demo" or "prod"
+]
+
+
+def main() -> None:
+    print("Checking Kalshi environment variables...\n")
+
+    missing = []
+    for name in REQUIRED_VARS:
+        value = os.getenv(name)
+        if value:
+            print(f"✅ {name} is set (hidden)")
+        else:
+            print(f"⚠️ {name} is NOT set")
+            missing.append(name)
+
+    if missing:
+        print("\nSome variables are missing:")
+        for name in missing:
+            print(f"  - {name}")
+
+        print(
+            "\nYou can export them before running the starter code, e.g.:\n"
+        )
+        example = textwrap.dedent(
+            """
+            export KALSHI_API_KEY=your_api_key_here
+            export KALSHI_API_SECRET=your_secret_here
+            export KALSHI_ENV=demo
+            """
+        ).strip()
+        print(example)
+    else:
+      print("\nAll required variables appear to be set. ✅")
+
+
+if __name__ == "__main__":
+    main()