diff --git a/internal/e2e/error_handling_test.go b/internal/e2e/error_handling_test.go
index 96ea902..7109d44 100644
--- a/internal/e2e/error_handling_test.go
+++ b/internal/e2e/error_handling_test.go
@@ -422,9 +422,7 @@ func TestE2E_ConcurrentPostCreation(t *testing.T) {
 
 		for _, user := range users {
 			u := user
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				client, err := ctx.loginUserSafe(t, u.Username, u.Password)
 				if err != nil || client == nil {
 					results <- nil
@@ -443,7 +441,7 @@ func TestE2E_ConcurrentPostCreation(t *testing.T) {
 
 				post, err := client.CreatePostSafe("Concurrent Post", url, "Content")
 				results <- post
-			}()
+			})
 		}
 
 		wg.Wait()
diff --git a/internal/e2e/error_recovery_test.go b/internal/e2e/error_recovery_test.go
index f8cd68f..beed19e 100644
--- a/internal/e2e/error_recovery_test.go
+++ b/internal/e2e/error_recovery_test.go
@@ -56,10 +56,8 @@ func TestE2E_DatabaseFailureRecovery(t *testing.T) {
 		var wg sync.WaitGroup
 		errors := make(chan error, 10)
 
-		for i := 0; i < 5; i++ {
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+		for range 5 {
+			wg.Go(func() {
 				conn, err := sqlDB.Conn(context.Background())
 				if err != nil {
 					errors <- err
@@ -68,7 +66,7 @@ func TestE2E_DatabaseFailureRecovery(t *testing.T) {
 				defer conn.Close()
 
 				time.Sleep(100 * time.Millisecond)
-			}()
+			})
 		}
 
 		wg.Wait()
@@ -297,7 +295,7 @@ func TestE2E_DatabaseConnectionPool(t *testing.T) {
 
 		initialStats := sqlDB.Stats()
 
-		for i := 0; i < 5; i++ {
+		for range 5 {
 			req, err := http.NewRequest("GET", ctx.baseURL+"/api/posts", nil)
 			if err != nil {
 				continue
diff --git a/internal/e2e/performance_test.go b/internal/e2e/performance_test.go
index e55ede1..6a3d449 100644
--- a/internal/e2e/performance_test.go
+++ b/internal/e2e/performance_test.go
@@ -59,7 +59,7 @@ func TestE2E_Performance(t *testing.T) {
 				var totalTime time.Duration
 				iterations := 10
 
-				for i := 0; i < iterations; i++ {
+				for range iterations {
 					req, err := endpoint.req()
 					if err != nil {
 						t.Fatalf("Failed to create request: %v", err)
@@ -98,11 +98,9 @@ func TestE2E_Performance(t *testing.T) {
 		var errorCount int64
 
 		var wg sync.WaitGroup
-		for i := 0; i < concurrency; i++ {
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
-				for j := 0; j < requestsPerGoroutine; j++ {
+		for range concurrency {
+			wg.Go(func() {
+				for range requestsPerGoroutine {
 					req, err := http.NewRequest("GET", ctx.baseURL+"/api/posts", nil)
 					if err != nil {
 						atomic.AddInt64(&errorCount, 1)
@@ -123,7 +121,7 @@ func TestE2E_Performance(t *testing.T) {
 						atomic.AddInt64(&errorCount, 1)
 					}
 				}
-			}()
+			})
 		}
 
 		wg.Wait()
@@ -138,7 +136,7 @@ func TestE2E_Performance(t *testing.T) {
 		createdUser := ctx.createUserWithCleanup(t, "dbperf", "StrongPass123!")
 		authClient := ctx.loginUser(t, createdUser.Username, createdUser.Password)
 
-		for i := 0; i < 10; i++ {
+		for i := range 10 {
 			authClient.CreatePost(t, fmt.Sprintf("Post %d", i), fmt.Sprintf("https://example.com/%d", i), "Content")
 		}
 
@@ -160,7 +158,7 @@ func TestE2E_Performance(t *testing.T) {
 		authClient := ctx.loginUser(t, createdUser.Username, createdUser.Password)
 
 		initialPosts := 50
-		for i := 0; i < initialPosts; i++ {
+		for i := range initialPosts {
 			authClient.CreatePost(t, fmt.Sprintf("Memory Test Post %d", i), fmt.Sprintf("https://example.com/mem%d", i), "Content")
 		}
 
@@ -271,16 +269,14 @@ func TestE2E_ConcurrentWrites(t *testing.T) {
 
 		for _, user := range users {
 			u := user
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				authClient, err := ctx.loginUserSafe(t, u.Username, u.Password)
 				if err != nil {
 					atomic.AddInt64(&errorCount, 1)
 					return
 				}
 
-				for i := 0; i < 5; i++ {
+				for i := range 5 {
 					post, err := authClient.CreatePostSafe(
 						fmt.Sprintf("Concurrent Post %d", i),
 						fmt.Sprintf("https://example.com/concurrent%d-%d", u.ID, i),
@@ -292,7 +288,7 @@ func TestE2E_ConcurrentWrites(t *testing.T) {
 						atomic.AddInt64(&errorCount, 1)
 					}
 				}
-			}()
+			})
 		}
 
 		wg.Wait()
@@ -311,7 +307,7 @@ func TestE2E_ResponseSize(t *testing.T) {
 		createdUser := ctx.createUserWithCleanup(t, "sizetest", "StrongPass123!")
 		authClient := ctx.loginUser(t, createdUser.Username, createdUser.Password)
 
-		for i := 0; i < 100; i++ {
+		for i := range 100 {
 			authClient.CreatePost(t, fmt.Sprintf("Post %d", i), fmt.Sprintf("https://example.com/%d", i), "Content")
 		}
 
diff --git a/internal/e2e/rate_limiting_test.go b/internal/e2e/rate_limiting_test.go
index 619ed8e..322f807 100644
--- a/internal/e2e/rate_limiting_test.go
+++ b/internal/e2e/rate_limiting_test.go
@@ -38,7 +38,7 @@ func TestE2E_RateLimitingHeaders(t *testing.T) {
 					t.Error("Expected Retry-After header when rate limited")
 				}
 
-				var jsonResponse map[string]interface{}
+				var jsonResponse map[string]any
 				body, _ := json.Marshal(map[string]string{})
 				_ = json.Unmarshal(body, &jsonResponse)
 
@@ -72,7 +72,7 @@ func TestE2E_RateLimitingHeaders(t *testing.T) {
 				if resp.StatusCode != http.StatusTooManyRequests {
 					t.Errorf("Expected status 429 on request %d, got %d", i+1, resp.StatusCode)
 				} else {
-					var errorResponse map[string]interface{}
+					var errorResponse map[string]any
 					body, _ := io.ReadAll(resp.Body)
 					if err := json.Unmarshal(body, &errorResponse); err == nil {
 						if errorResponse["error"] == nil {
diff --git a/internal/e2e/version_test.go b/internal/e2e/version_test.go
index e048c67..c886ff1 100644
--- a/internal/e2e/version_test.go
+++ b/internal/e2e/version_test.go
@@ -30,12 +30,12 @@ func TestE2E_VersionEndpoint(t *testing.T) {
 			return
 		}
 
-		var apiInfo map[string]interface{}
+		var apiInfo map[string]any
 		if err := json.NewDecoder(resp.Body).Decode(&apiInfo); err != nil {
 			t.Fatalf("Failed to decode API info response: %v", err)
 		}
 
-		data, ok := apiInfo["data"].(map[string]interface{})
+		data, ok := apiInfo["data"].(map[string]any)
 		if !ok {
 			t.Fatalf("API info data is not a map")
 		}
@@ -74,12 +74,12 @@ func TestE2E_VersionEndpoint(t *testing.T) {
 			return
 		}
 
-		var healthInfo map[string]interface{}
+		var healthInfo map[string]any
 		if err := json.NewDecoder(resp.Body).Decode(&healthInfo); err != nil {
 			t.Fatalf("Failed to decode health response: %v", err)
 		}
 
-		data, ok := healthInfo["data"].(map[string]interface{})
+		data, ok := healthInfo["data"].(map[string]any)
 		if !ok {
 			t.Fatalf("Health data is not a map")
 		}
@@ -130,18 +130,18 @@ func TestE2E_VersionEndpoint(t *testing.T) {
 			return
 		}
 
-		var apiInfo map[string]interface{}
+		var apiInfo map[string]any
 		if err := json.NewDecoder(apiResp.Body).Decode(&apiInfo); err != nil {
 			t.Fatalf("Failed to decode API info: %v", err)
 		}
 
-		var healthInfo map[string]interface{}
+		var healthInfo map[string]any
 		if err := json.NewDecoder(healthResp.Body).Decode(&healthInfo); err != nil {
 			t.Fatalf("Failed to decode health info: %v", err)
 		}
 
-		apiData, _ := apiInfo["data"].(map[string]interface{})
-		healthData, _ := healthInfo["data"].(map[string]interface{})
+		apiData, _ := apiInfo["data"].(map[string]any)
+		healthData, _ := healthInfo["data"].(map[string]any)
 
 		apiVersion, apiOk := apiData["version"].(string)
 		healthVersion, healthOk := healthData["version"].(string)
@@ -169,12 +169,12 @@ func TestE2E_VersionEndpoint(t *testing.T) {
 			return
 		}
 
-		var apiInfo map[string]interface{}
+		var apiInfo map[string]any
 		if err := json.NewDecoder(resp.Body).Decode(&apiInfo); err != nil {
 			t.Fatalf("Failed to decode API info: %v", err)
 		}
 
-		data, ok := apiInfo["data"].(map[string]interface{})
+		data, ok := apiInfo["data"].(map[string]any)
 		if !ok {
 			return
 		}
diff --git a/internal/e2e/workflows_realistic_test.go b/internal/e2e/workflows_realistic_test.go
index 3bffced..8ec926c 100644
--- a/internal/e2e/workflows_realistic_test.go
+++ b/internal/e2e/workflows_realistic_test.go
@@ -455,7 +455,7 @@ func TestE2E_ConcurrentRequestsWithSameSession(t *testing.T) {
 		authClient := ctx.loginUser(t, createdUser.Username, createdUser.Password)
 
 		results := make(chan bool, 5)
-		for i := 0; i < 5; i++ {
+		for range 5 {
 			go func() {
 				profile := authClient.GetProfile(t)
 				results <- (profile != nil && profile.Data.Username == createdUser.Username)
@@ -463,7 +463,7 @@ func TestE2E_ConcurrentRequestsWithSameSession(t *testing.T) {
 		}
 
 		successCount := 0
-		for i := 0; i < 5; i++ {
+		for range 5 {
 			if <-results {
 				successCount++
 			}
@@ -562,7 +562,7 @@ func TestE2E_RapidSuccessiveActions(t *testing.T) {
 
 		post := authClient.CreatePost(t, "Rapid Vote Test", "https://example.com/rapid", "Content")
 
-		for i := 0; i < 10; i++ {
+		for i := range 10 {
 			voteType := "up"
 			if i%2 == 0 {
 				voteType = "down"
diff --git a/internal/e2e/workflows_test.go b/internal/e2e/workflows_test.go
index 7de40ad..6344558 100644
--- a/internal/e2e/workflows_test.go
+++ b/internal/e2e/workflows_test.go
@@ -134,9 +134,7 @@ func TestE2E_ConcurrentUserWorkflows(t *testing.T) {
 
 		for _, user := range users {
 			u := user
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				var err error
 				authClient, loginErr := ctx.loginUserSafe(t, u.Username, u.Password)
 				if loginErr != nil || authClient == nil || authClient.Token == "" {
@@ -157,7 +155,7 @@ func TestE2E_ConcurrentUserWorkflows(t *testing.T) {
 				case results <- result{userID: u.ID, err: err}:
 				case <-done:
 				}
-			}()
+			})
 		}
 
 		go func() {