feat(opencode): add interactive split-footer mode to run (#23557)

packages/opencode/src/cli/cmd/run/runtime.stdin.ts

@@ -0,0 +1,37 @@
+import fs from "fs"
+import * as tty from "node:tty"
+
+export const INTERACTIVE_INPUT_ERROR = "--interactive requires a controlling terminal for input"
+
+type InteractiveStdin = {
+  stdin: NodeJS.ReadStream
+  cleanup?: () => void
+}
+
+function openTerminalStdin(path: string): NodeJS.ReadStream {
+  return new tty.ReadStream(fs.openSync(path, "r"))
+}
+
+export function resolveInteractiveStdin(
+  stdin: NodeJS.ReadStream = process.stdin,
+  open: (path: string) => NodeJS.ReadStream = openTerminalStdin,
+  platform = process.platform,
+): InteractiveStdin {
+  if (stdin.isTTY) {
+    return { stdin }
+  }
+
+  const file = platform === "win32" ? "CONIN$" : "/dev/tty"
+
+  try {
+    const stream = open(file)
+    return {
+      stdin: stream,
+      cleanup: () => {
+        stream.destroy()
+      },
+    }
+  } catch (error) {
+    throw new Error(INTERACTIVE_INPUT_ERROR, { cause: error })
+  }
+}