diff --git a/src/renderer/src/runtime/host-session-mirror-hydration-drain.test.ts b/src/renderer/src/runtime/host-session-mirror-hydration-drain.test.ts
index 0b96e293c19..19738ffcb09 100644
--- a/src/renderer/src/runtime/host-session-mirror-hydration-drain.test.ts
+++ b/src/renderer/src/runtime/host-session-mirror-hydration-drain.test.ts
@@ -1,7 +1,9 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { clearRuntimeEnvironmentConnectionGenerationsForTests } from '@/store/slices/runtime-status'
 import {
+  getParkedHostSessionMirrorWaiterCountForTests,
   markHostSessionMirrorHydrated,
+  MAX_PARKED_HOST_SESSION_MIRROR_WAITERS,
   parkUntilHostSessionMirrorHydrates,
   resetHostSessionMirrorHydrationForTests
 } from './host-session-mirror-hydration'
@@ -28,4 +30,14 @@ describe('host session mirror hydration drain', () => {
     expect(() => markHostSessionMirrorHydrated(ENVIRONMENT_ID)).not.toThrow()
     expect(secondReplay).toHaveBeenCalledTimes(1)
   })
+
+  it('bounds parked waiter growth when environments churn', () => {
+    for (let index = 0; index < MAX_PARKED_HOST_SESSION_MIRROR_WAITERS + 4; index += 1) {
+      parkUntilHostSessionMirrorHydrates(`env-${index}`, 'repo::worktree', () => {})
+    }
+
+    expect(getParkedHostSessionMirrorWaiterCountForTests()).toBe(
+      MAX_PARKED_HOST_SESSION_MIRROR_WAITERS
+    )
+  })
 })
diff --git a/src/renderer/src/runtime/host-session-mirror-hydration.ts b/src/renderer/src/runtime/host-session-mirror-hydration.ts
index aaeb8685d73..93e23fc53d9 100644
--- a/src/renderer/src/runtime/host-session-mirror-hydration.ts
+++ b/src/renderer/src/runtime/host-session-mirror-hydration.ts
@@ -16,6 +16,7 @@ type ParkedMirrorWaiter = { environmentId: string; worktreeId: string; run: () =
 const hydratedGenerationByEnvironment = new Map<string, number>()
 const hydratedGenerationByWorktree = new Map<string, number>()
 const parkedWaitersByWorktree = new Map<string, ParkedMirrorWaiter>()
+export const MAX_PARKED_HOST_SESSION_MIRROR_WAITERS = 512
 
 function worktreeKey(environmentId: string, worktreeId: string): string {
   return `${environmentId}\0${worktreeId}`
@@ -113,11 +114,24 @@ export function parkUntilHostSessionMirrorHydrates(
   worktreeId: string,
   run: () => void
 ): void {
-  parkedWaitersByWorktree.set(worktreeKey(environmentId, worktreeId), {
+  const key = worktreeKey(environmentId, worktreeId)
+  parkedWaitersByWorktree.delete(key)
+  parkedWaitersByWorktree.set(key, {
     environmentId,
     worktreeId,
     run
   })
+  while (parkedWaitersByWorktree.size > MAX_PARKED_HOST_SESSION_MIRROR_WAITERS) {
+    const oldest = parkedWaitersByWorktree.keys().next()
+    if (oldest.done || oldest.value === key) {
+      break
+    }
+    parkedWaitersByWorktree.delete(oldest.value)
+  }
+}
+
+export function getParkedHostSessionMirrorWaiterCountForTests(): number {
+  return parkedWaitersByWorktree.size
 }
 
 export function resetHostSessionMirrorHydrationForTests(): void {