diff --git a/constants.go b/constants.go
index 8018f88..2e65cab 100644
--- a/constants.go
+++ b/constants.go
@@ -43,8 +43,8 @@ const (
 
 // Field Sets for API requests
 const (
-	// Post fields
-	PostExtendedFields = "id,media_product_type,media_type,media_url,permalink,owner,username,text,timestamp,shortcode,thumbnail_url,children,is_quote_post,alt_text,link_attachment_url,has_replies,reply_audience,quoted_post,reposted_post,gif_url"
+	// Post fields (is_verified and profile_picture_url added December 16, 2025 for replies/mentions)
+	PostExtendedFields = "id,media_product_type,media_type,media_url,permalink,owner,username,text,timestamp,shortcode,thumbnail_url,children,is_quote_post,alt_text,link_attachment_url,has_replies,reply_audience,quoted_post,reposted_post,gif_url,is_verified,profile_picture_url"
 
 	// Ghost Post fields
 	GhostPostFields = "id,media_product_type,media_type,media_url,permalink,owner,username,text,timestamp,shortcode,thumbnail_url,ghost_post_status,ghost_post_expiration_timestamp"
@@ -53,7 +53,8 @@ const (
 	UserProfileFields = "id,username,name,threads_profile_picture_url,threads_biography,is_verified"
 
 	// Reply fields (includes additional reply-specific fields)
-	ReplyFields = "id,media_product_type,media_type,media_url,permalink,username,text,timestamp,shortcode,thumbnail_url,children,is_quote_post,has_replies,root_post,replied_to,is_reply,is_reply_owned_by_me,reply_audience,quoted_post,reposted_post,gif_url,alt_text,hide_status,topic_tag"
+	// is_verified and profile_picture_url added December 16, 2025 (only available on direct replies for conversations)
+	ReplyFields = "id,media_product_type,media_type,media_url,permalink,username,text,timestamp,shortcode,thumbnail_url,children,is_quote_post,has_replies,root_post,replied_to,is_reply,is_reply_owned_by_me,reply_audience,quoted_post,reposted_post,gif_url,alt_text,hide_status,topic_tag,is_verified,profile_picture_url"
 
 	// Container status fields
 	ContainerStatusFields = "id,status,error_message"
@@ -93,3 +94,11 @@ const (
 	ErrEmptyContainerID = "Container ID is required"
 	ErrEmptySearchQuery = "Search query is required"
 )
+
+// API Error Codes returned by the Threads API
+const (
+	// ErrCodeLinkLimitExceeded is returned when a post contains more than 5 unique links.
+	// This error occurs during media container creation (POST /{threads-user-id}/threads).
+	// Added December 22, 2025. Reduce the number of unique links to 5 or fewer to resolve.
+	ErrCodeLinkLimitExceeded = "THREADS_API__LINK_LIMIT_EXCEEDED"
+)
diff --git a/tests/integration/integration_test.go b/tests/integration/integration_test.go
index 872d008..102308c 100644
--- a/tests/integration/integration_test.go
+++ b/tests/integration/integration_test.go
@@ -892,6 +892,53 @@ func TestIntegration_ValidationErrors(t *testing.T) {
 			t.Logf("Validation error (expected): %v", err)
 		}
 	})
+
+	t.Run("TooManyLinks", func(t *testing.T) {
+		// Try to create post with more than 5 unique links (should fail validation)
+		// Added December 22, 2025: THREADS_API__LINK_LIMIT_EXCEEDED
+		content := &threads.TextPostContent{
+			Text: "Check out these links: https://example1.com https://example2.com https://example3.com https://example4.com https://example5.com https://example6.com",
+		}
+
+		_, err := client.CreateTextPost(context.Background(), content)
+		if err == nil {
+			t.Error("Expected validation error for too many links (max 5)")
+		} else {
+			t.Logf("Validation error (expected): %v", err)
+		}
+	})
+
+	t.Run("TooManyLinksWithLinkAttachment", func(t *testing.T) {
+		// Try to create post with 5 links in text + 1 different link_attachment (should fail validation)
+		content := &threads.TextPostContent{
+			Text:           "Links: https://example1.com https://example2.com https://example3.com https://example4.com https://example5.com",
+			LinkAttachment: "https://example6.com", // 6th unique link
+		}
+
+		_, err := client.CreateTextPost(context.Background(), content)
+		if err == nil {
+			t.Error("Expected validation error for too many links with link_attachment")
+		} else {
+			t.Logf("Validation error (expected): %v", err)
+		}
+	})
+
+	t.Run("LinksWithDuplicateLinkAttachment", func(t *testing.T) {
+		// 5 unique links in text + link_attachment that duplicates one = should pass (5 unique total)
+		// This tests that duplicate link_attachment is not double-counted
+		content := &threads.TextPostContent{
+			Text:           "Links: https://example1.com https://example2.com https://example3.com https://example4.com https://example5.com",
+			LinkAttachment: "https://example1.com", // Duplicate, should not count as 6th
+		}
+
+		// This should NOT fail validation (5 unique links is the limit)
+		err := client.ValidateTextPostContent(content)
+		if err != nil {
+			t.Errorf("Unexpected validation error for 5 unique links with duplicate link_attachment: %v", err)
+		} else {
+			t.Log("Validation passed (expected): 5 unique links with duplicate link_attachment")
+		}
+	})
 }
 
 // TestIntegration_GIFPosts tests GIF attachment functionality
diff --git a/types.go b/types.go
index 7a7e5ad..bbaec81 100644
--- a/types.go
+++ b/types.go
@@ -75,6 +75,14 @@ type Post struct {
 	TopicTag                     string        `json:"topic_tag,omitempty"`
 	GhostPostStatus              string        `json:"ghost_post_status,omitempty"`
 	GhostPostExpirationTimestamp Time          `json:"ghost_post_expiration_timestamp,omitempty"`
+	// IsVerified indicates if the post author's profile is verified on Threads.
+	// Available for replies and mentions. For conversations, only available on direct replies.
+	// Added December 16, 2025.
+	IsVerified bool `json:"is_verified,omitempty"`
+	// ProfilePictureURL is the URL of the post author's profile picture on Threads.
+	// Available for replies and mentions. For conversations, only available on direct replies.
+	// Added December 16, 2025.
+	ProfilePictureURL string `json:"profile_picture_url,omitempty"`
 }
 
 // User represents a Threads user profile with app-scoped data.