fix(cli): bound telemetry shutdown on signals

Refs #1356

apps/cli/src/process-shutdown.ts

@@ -0,0 +1,57 @@
+/** Bounded, escalating process shutdown for the long-lived CLI surfaces. */
+
+/** Maximum grace allowed for the application tree to dispose before process exit. */
+export const PROCESS_SHUTDOWN_TIMEOUT_MS = 5_000
+
+/** Process-exit controller shared by normal completion and Unix signal handlers. */
+export interface ProcessShutdown {
+  /** Start or join graceful disposal before exiting with `code`. */
+  shutdown(code: number): Promise<void>
+  /** Start graceful disposal, or force exit when a shutdown is already running. */
+  interrupt(code: number): void
+}
+
+/**
+ * Create one process-exit controller around an application disposer.
+ * @param dispose - Whole-application teardown that resolves at quiescence.
+ * @param exit - Process exit boundary, replaceable by tests.
+ * @param timeoutMs - Grace before forced exit, replaceable by tests.
+ * @returns A controller whose normal calls coalesce and whose repeated signal call escalates.
+ */
+export function createProcessShutdown(
+  dispose: () => Promise<void>,
+  exit: (code: number) => void = (code) => { process.exit(code) },
+  timeoutMs = PROCESS_SHUTDOWN_TIMEOUT_MS,
+): ProcessShutdown {
+  let pending: Promise<void> | undefined
+  let timeout: ReturnType<typeof setTimeout> | undefined
+  let exited = false
+
+  const exitOnce = (code: number): void => {
+    if (exited) return
+    exited = true
+    if (timeout !== undefined) clearTimeout(timeout)
+    exit(code)
+  }
+
+  const shutdown = (code: number): Promise<void> => {
+    if (pending !== undefined) return pending
+    timeout = setTimeout(() => { exitOnce(code) }, timeoutMs)
+    pending = Promise.resolve().then(dispose).then(
+      () => { exitOnce(code) },
+      () => { exitOnce(code) },
+    )
+    return pending
+  }
+
+  return {
+    shutdown,
+    interrupt(code) {
+      if (pending !== undefined) {
+        exitOnce(code)
+        return
+      }
+      void shutdown(code)
+    },
+  }
+}