diff --git a/include/ircd/ctx/promise.h b/include/ircd/ctx/promise.h
index a3490961f..a364511d5 100644
--- a/include/ircd/ctx/promise.h
+++ b/include/ircd/ctx/promise.h
@@ -196,11 +196,11 @@ ircd::ctx::promise<T>::set_value(T&& val)
 {
 	assert(valid());
 	assert(pending(*st));
+	st->val = std::move(val);
 	auto *const st{this->st};
 	invalidate(*st);
 	set_ready(*st);
-	st->val = std::move(val);
-	st->cond.notify_all();
+	notify(*st);
 }
 
 template<class T>
@@ -209,11 +209,11 @@ ircd::ctx::promise<T>::set_value(const T &val)
 {
 	assert(valid());
 	assert(pending(*st));
+	st->val = val;
 	auto *const st{this->st};
 	invalidate(*st);
 	set_ready(*st);
-	st->val = val;
-	st->cond.notify_all();
+	notify(*st);
 }
 
 inline void
@@ -224,7 +224,7 @@ ircd::ctx::promise<void>::set_value()
 	auto *const st{this->st};
 	invalidate(*st);
 	set_ready(*st);
-	st->cond.notify_all();
+	notify(*st);
 }
 
 template<class T>
@@ -233,11 +233,11 @@ ircd::ctx::promise<T>::set_exception(std::exception_ptr eptr)
 {
 	assert(valid());
 	assert(pending(*st));
+	st->eptr = std::move(eptr);
 	auto *const st{this->st};
 	invalidate(*st);
 	set_ready(*st);
-	st->eptr = std::move(eptr);
-	st->cond.notify_all();
+	notify(*st);
 }
 
 inline void
@@ -245,11 +245,11 @@ ircd::ctx::promise<void>::set_exception(std::exception_ptr eptr)
 {
 	assert(valid());
 	assert(pending(*st));
+	st->eptr = std::move(eptr);
 	auto *const st{this->st};
 	invalidate(*st);
 	set_ready(*st);
-	st->eptr = std::move(eptr);
-	st->cond.notify_all();
+	notify(*st);
 }
 
 template<class T>
diff --git a/include/ircd/ctx/shared_state.h b/include/ircd/ctx/shared_state.h
index f2cf18b2a..53a5ddb95 100644
--- a/include/ircd/ctx/shared_state.h
+++ b/include/ircd/ctx/shared_state.h
@@ -24,12 +24,14 @@ namespace ircd::ctx
 	template<class T> bool pending(const shared_state<T> &);
 	template<class T> bool ready(const shared_state<T> &);
 	template<class T> void set_ready(shared_state<T> &);
+	template<class T> void notify(shared_state<T> &);
 }
 
 struct ircd::ctx::shared_state_base
 {
 	mutable dock cond;
 	std::exception_ptr eptr;
+	std::function<void (shared_state_base &)> then;
 };
 
 template<class T>
@@ -53,6 +55,24 @@ struct ircd::ctx::shared_state<void>
 	promise<void> *p {nullptr};
 };
 
+template<class T>
+void
+ircd::ctx::notify(shared_state<T> &st)
+{
+	st.cond.notify_all();
+
+	if(!st.then)
+		return;
+
+	if(!current)
+		return st.then(st);
+
+	ircd::post([&st]
+	{
+		st.then(st);
+	});
+}
+
 template<class T>
 void
 ircd::ctx::set_ready(shared_state<T> &st)