diff --git a/assertions/manager.go b/assertions/manager.go
index 6a4504d790..7578f8c5c0 100644
--- a/assertions/manager.go
+++ b/assertions/manager.go
@@ -94,6 +94,8 @@ type Manager struct {
 	autoDeposit                 bool
 	autoAllowanceApproval       bool
 	maxGetLogBlocks             uint64
+	confirming                  *threadsafe.LruSet[protocol.AssertionHash]
+	confirmQueueMutex           sync.Mutex
 }
 
 type assertionChainData struct {
@@ -248,6 +250,8 @@ func NewManager(
 		autoDeposit:                 true,
 		autoAllowanceApproval:       true,
 		maxGetLogBlocks:             1000,
+		confirming:                  threadsafe.NewLruSet[protocol.AssertionHash](maxAssertions),
+		confirmQueueMutex:           sync.Mutex{},
 	}
 	for _, o := range opts {
 		o(m)
diff --git a/assertions/poster.go b/assertions/poster.go
index 0148b8e6aa..fcb3c26563 100644
--- a/assertions/poster.go
+++ b/assertions/poster.go
@@ -196,7 +196,8 @@ func (m *Manager) PostAssertionBasedOnParent(
 		"postedExecutionState", fmt.Sprintf("%+v", newState),
 		"assertionHash", assertion.Id(),
 	)
-	m.observedCanonicalAssertions <- assertion.Id()
+
+	m.sendToConfirmationQueue(assertion.Id(), "PostAssertionBasedOnParent")
 	return option.Some(assertion), nil
 }
 
diff --git a/assertions/sync.go b/assertions/sync.go
index da27f05640..7193579d0a 100644
--- a/assertions/sync.go
+++ b/assertions/sync.go
@@ -308,7 +308,7 @@ func (m *Manager) findCanonicalAssertionBranch(
 				cursor = assertion.AssertionHash
 				m.assertionChainData.latestAgreedAssertion = cursor
 				m.assertionChainData.canonicalAssertions[cursor] = assertion
-				m.observedCanonicalAssertions <- cursor
+				m.sendToConfirmationQueue(cursor, "findCanonicalAssertionBranch")
 			}
 		}
 	}
@@ -365,7 +365,7 @@ func (m *Manager) respondToAnyInvalidAssertions(
 					m.assertionChainData.canonicalAssertions[postedAssertionHash] = postedRival
 					m.submittedAssertions.Insert(postedAssertionHash)
 					m.submittedRivalsCount++
-					m.observedCanonicalAssertions <- postedAssertionHash
+					m.sendToConfirmationQueue(postedAssertionHash, "respondToAnyInvalidAssertions")
 				}
 			}
 		}
@@ -559,3 +559,26 @@ func (m *Manager) saveAssertionToDB(ctx context.Context, creationInfo *protocol.
 		Status:                   status.String(),
 	})
 }
+
+// Send assertion to confirmation queue
+func (m *Manager) sendToConfirmationQueue(assertionHash protocol.AssertionHash, addedBy string) {
+	m.confirmQueueMutex.Lock()
+	defer m.confirmQueueMutex.Unlock()
+
+	// Check if assertion is already in confirmation queue
+	if m.confirming.Has(assertionHash) {
+		log.Debug("Assertion already in confirmation queue", "assertionHash", assertionHash, "addedBy", addedBy)
+		return // Already in confirmation queue, skip
+	}
+	log.Info("Sending assertion to confirmation queue", "assertionHash", assertionHash, "addedBy", addedBy)
+	// Mark as confirming
+	m.confirming.Insert(assertionHash)
+
+	// Send to confirmation queue
+	select {
+	case m.observedCanonicalAssertions <- assertionHash:
+	default:
+		m.confirming.Delete(assertionHash)
+		log.Warn("Failed to send assertion to confirmation queue: channel full", "assertionHash", assertionHash, "addedBy", addedBy)
+	}
+}
diff --git a/assertions/sync_test.go b/assertions/sync_test.go
index 53aace50d3..034426fa95 100644
--- a/assertions/sync_test.go
+++ b/assertions/sync_test.go
@@ -136,6 +136,7 @@ func Test_findCanonicalAssertionBranch(t *testing.T) {
 		execProvider:                provider,
 		chain:                       setup.Chains[0],
 		observedCanonicalAssertions: make(chan protocol.AssertionHash),
+		confirming:                  threadsafe.NewLruSet[protocol.AssertionHash](1000),
 		assertionChainData: &assertionChainData{
 			latestAgreedAssertion: numToAssertionHash(1),
 			canonicalAssertions:   make(map[protocol.AssertionHash]*protocol.AssertionCreatedInfo),
@@ -267,6 +268,7 @@ func Test_respondToAnyInvalidAssertions(t *testing.T) {
 	manager := &Manager{
 		observedCanonicalAssertions: make(chan protocol.AssertionHash),
 		submittedAssertions:         threadsafe.NewLruSet(1000, threadsafe.LruSetWithMetric[protocol.AssertionHash]("submittedAssertions")),
+		confirming:                  threadsafe.NewLruSet[protocol.AssertionHash](1000),
 		assertionChainData: &assertionChainData{
 			latestAgreedAssertion: numToAssertionHash(1),
 			canonicalAssertions:   make(map[protocol.AssertionHash]*protocol.AssertionCreatedInfo),