feat: support suspending ui (#173)

Co-authored-by: Shubham Naik <shub@memgpt.ai>

src/cli/hooks/useSuspend/useSuspend.ts

@@ -0,0 +1,46 @@
+import { useInput, useStdin } from "ink";
+import { useCallback, useEffect, useState } from "react";
+
+export function useSuspend() {
+  const { stdin, isRawModeSupported } = useStdin();
+  // Use a state variable to force a re-render when needed
+  const [resumeKey, setResumeKey] = useState(0);
+
+  const forceUpdate = useCallback(() => {
+    setResumeKey((prev) => prev + 1);
+  }, []);
+
+  useInput((input, key) => {
+    // Handle CTRL-Z for suspend
+    if (key.ctrl && input === "z") {
+      if (stdin && isRawModeSupported) {
+        stdin.setRawMode(false);
+      }
+
+      process.kill(process.pid, "SIGTSTP");
+      return;
+    }
+  });
+
+  // Handle the SIGCONT (fg command) resume
+  useEffect(() => {
+    const handleResume = () => {
+      if (stdin && isRawModeSupported && stdin.setRawMode) {
+        stdin.setRawMode(true);
+      }
+
+      // clear the console
+      process.stdout.write("\x1B[H\x1B[2J");
+
+      forceUpdate();
+    };
+
+    process.on("SIGCONT", handleResume);
+
+    return () => {
+      process.off("SIGCONT", handleResume);
+    };
+  }, [stdin, isRawModeSupported, forceUpdate]);
+
+  return resumeKey;
+}