diff --git a/cmd/goyco/commands/seed.go b/cmd/goyco/commands/seed.go
index 780fa3c..e47f4a5 100644
--- a/cmd/goyco/commands/seed.go
+++ b/cmd/goyco/commands/seed.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"math/big"
 	"os"
+	"strings"
 
 	"goyco/internal/config"
 	"goyco/internal/database"
@@ -169,6 +170,10 @@ func seedDatabase(userRepo repositories.UserRepository, postRepo repositories.Po
 		progress.Complete()
 	}
 
+	if err := validateSeedConsistency(postRepo, voteRepo, allUsers, posts); err != nil {
+		return fmt.Errorf("seed consistency validation failed: %w", err)
+	}
+
 	if IsJSONOutput() {
 		outputJSON(map[string]any{
 			"action": "seed_completed",
@@ -188,7 +193,32 @@ func seedDatabase(userRepo repositories.UserRepository, postRepo repositories.Po
 	return nil
 }
 
+func findExistingSeedUser(userRepo repositories.UserRepository) (*database.User, error) {
+	users, err := userRepo.GetAll(100, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, user := range users {
+		if len(user.Username) >= 11 && user.Username[:11] == "seed_admin_" {
+			if len(user.Email) >= 13 && strings.HasSuffix(user.Email, "@goyco.local") {
+				emailPrefix := user.Email[:len(user.Email)-13]
+				if len(emailPrefix) >= 11 && emailPrefix[:11] == "seed_admin_" {
+					return &user, nil
+				}
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("no existing seed user found")
+}
+
 func ensureSeedUser(userRepo repositories.UserRepository) (*database.User, error) {
+	existingUser, err := findExistingSeedUser(userRepo)
+	if err == nil && existingUser != nil {
+		return existingUser, nil
+	}
+
 	seedPassword := "seed-password"
 	randomID := generateRandomIdentifier()
 	seedUsername := fmt.Sprintf("seed_admin_%s", randomID)
@@ -427,3 +457,35 @@ func getVoteCounts(voteRepo repositories.VoteRepository, postID uint) (int, int,
 
 	return upVotes, downVotes, nil
 }
+
+func validateSeedConsistency(postRepo repositories.PostRepository, voteRepo repositories.VoteRepository, users []database.User, posts []database.Post) error {
+	userIDs := make(map[uint]bool)
+	for _, user := range users {
+		userIDs[user.ID] = true
+	}
+
+	for _, post := range posts {
+		if post.AuthorID == nil {
+			return fmt.Errorf("post %d has no author", post.ID)
+		}
+		if !userIDs[*post.AuthorID] {
+			return fmt.Errorf("post %d has invalid author ID %d", post.ID, *post.AuthorID)
+		}
+
+		votes, err := voteRepo.GetByPostID(post.ID)
+		if err != nil {
+			return fmt.Errorf("get votes for post %d: %w", post.ID, err)
+		}
+
+		for _, vote := range votes {
+			if vote.UserID != nil && !userIDs[*vote.UserID] {
+				return fmt.Errorf("vote %d has invalid user ID %d", vote.ID, *vote.UserID)
+			}
+			if vote.PostID != post.ID {
+				return fmt.Errorf("vote %d has invalid post ID %d (expected %d)", vote.ID, vote.PostID, post.ID)
+			}
+		}
+	}
+
+	return nil
+}