feat(api): add groups and tokens handlers, refactor routes

Add new API endpoints and clean up handler interfaces:

- groups/handlers.go: New lab group management API
  * CRUD operations for lab groups
  * Member management with role assignment (admin/member/viewer)
  * Group listing and membership queries

- tokens/handlers.go: Token generation and validation endpoints
  * Create access tokens for public task sharing
  * Validate tokens for secure access
  * Token revocation and cleanup

- routes.go: Refactor handler registration
  * Integrate groups handler into WebSocket routes
  * Remove nil parameters from all handler constructors
  * Cleaner dependency injection pattern

- Handler interface cleanup across all modules:
  * jobs/handlers.go: Remove unused nil privacyEnforcer parameter
  * jupyter/handlers.go: Streamline initialization
  * scheduler/handlers.go: Consistent constructor signature
  * ws/handler.go: Add groups handler to dependencies

internal/api/helpers/db_helpers.go

@@ -9,21 +9,25 @@ import (
 
 // DBContext provides a standard database operation context.
 // It creates a context with the specified timeout and returns the context and cancel function.
+// #nosec G118 -- CancelFunc is returned to caller for proper lifecycle management
 func DBContext(timeout time.Duration) (context.Context, context.CancelFunc) {
 	return context.WithTimeout(context.Background(), timeout)
 }
 
 // DBContextShort returns a short-lived context for quick DB operations (3 seconds).
+// #nosec G118 -- CancelFunc is returned to caller for proper lifecycle management
 func DBContextShort() (context.Context, context.CancelFunc) {
 	return context.WithTimeout(context.Background(), 3*time.Second)
 }
 
 // DBContextMedium returns a medium-lived context for standard DB operations (5 seconds).
+// #nosec G118 -- CancelFunc is returned to caller for proper lifecycle management
 func DBContextMedium() (context.Context, context.CancelFunc) {
 	return context.WithTimeout(context.Background(), 5*time.Second)
 }
 
 // DBContextLong returns a long-lived context for complex DB operations (10 seconds).
+// #nosec G118 -- CancelFunc is returned to caller for proper lifecycle management
 func DBContextLong() (context.Context, context.CancelFunc) {
 	return context.WithTimeout(context.Background(), 10*time.Second)
 }

internal/api/middleware.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/jfraeys/fetch_ml/internal/auth"
 	"github.com/jfraeys/fetch_ml/internal/middleware"
 )
 
@@ -18,6 +19,7 @@ func (s *Server) wrapWithMiddleware(mux *http.ServeMux) http.Handler {
 		}
 
 		handler := s.sec.APIKeyAuth(mux)
+		handler = s.provisionUserMiddleware(handler)
 		handler = s.sec.RateLimit(handler)
 		handler = middleware.SecurityHeaders(handler)
 		handler = middleware.CORS(s.config.Security.AllowedOrigins)(handler)
@@ -33,3 +35,19 @@ func (s *Server) wrapWithMiddleware(mux *http.ServeMux) http.Handler {
 		handler.ServeHTTP(w, r)
 	})
 }
+
+// provisionUserMiddleware provisions new users on first login
+func (s *Server) provisionUserMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Only provision if database is available
+		if s.db != nil {
+			if user := auth.GetUserFromContext(r.Context()); user != nil {
+				if err := s.db.ProvisionUserOnFirstLogin(user.Name); err != nil {
+					// Log error but don't fail the request - provisioning is best-effort
+					s.logger.Error("failed to provision user on first login", "user", user.Name, "error", err)
+				}
+			}
+		}
+		next.ServeHTTP(w, r)
+	})
+}

internal/api/middleware/validation.go

@@ -75,10 +75,13 @@ func (v *ValidationMiddleware) ValidateRequest(next http.Handler) http.Handler {
 		if err := openapi3filter.ValidateRequest(r.Context(), requestValidationInput); err != nil {
 			w.Header().Set("Content-Type", "application/json")
 			w.WriteHeader(http.StatusBadRequest)
-			json.NewEncoder(w).Encode(map[string]any{
+			if encodeErr := json.NewEncoder(w).Encode(map[string]any{
 				"error":   "validation failed",
 				"message": err.Error(),
-			})
+			}); encodeErr != nil {
+				// Log but don't return - we've already sent headers
+				_ = encodeErr
+			}
 			return
 		}
 

internal/api/plugins/handlers.go

@@ -2,6 +2,7 @@
 package plugins
 
 import (
+	"slices"
 	"encoding/json"
 	"net/http"
 	"time"
@@ -98,7 +99,9 @@ func (h *Handler) GetV1Plugins(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(plugins)
+	if err := json.NewEncoder(w).Encode(plugins); err != nil {
+		h.logger.Warn("failed to encode plugins response", "error", err)
+	}
 }
 
 // GetV1PluginsPluginName handles GET /v1/plugins/{pluginName}
@@ -136,7 +139,9 @@ func (h *Handler) GetV1PluginsPluginName(w http.ResponseWriter, r *http.Request)
 	}
 
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(info)
+	if err := json.NewEncoder(w).Encode(info); err != nil {
+		h.logger.Warn("failed to encode plugin info", "error", err)
+	}
 }
 
 // GetV1PluginsPluginNameConfig handles GET /v1/plugins/{pluginName}/config
@@ -160,7 +165,9 @@ func (h *Handler) GetV1PluginsPluginNameConfig(w http.ResponseWriter, r *http.Re
 	}
 
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(cfg)
+	if err := json.NewEncoder(w).Encode(cfg); err != nil {
+		h.logger.Warn("failed to encode plugin config", "error", err)
+	}
 }
 
 // PutV1PluginsPluginNameConfig handles PUT /v1/plugins/{pluginName}/config
@@ -195,11 +202,13 @@ func (h *Handler) PutV1PluginsPluginNameConfig(w http.ResponseWriter, r *http.Re
 		Status:          "healthy",
 		Config:          newConfig,
 		RequiresRestart: false,
-		Version:         "1.0.0",
+		Version:         "1.0.0", // TODO: should this be checked
 	}
 
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(info)
+	if err := json.NewEncoder(w).Encode(info); err != nil {
+		h.logger.Warn("failed to encode plugin info", "error", err)
+	}
 }
 
 // DeleteV1PluginsPluginNameConfig handles DELETE /v1/plugins/{pluginName}/config
@@ -255,14 +264,16 @@ func (h *Handler) GetV1PluginsPluginNameHealth(w http.ResponseWriter, r *http.Re
 		status = "stopped"
 	}
 
-	response := map[string]interface{}{
+	response := map[string]any{
 		"status":    status,
 		"version":   "1.0.0",
 		"timestamp": time.Now().UTC(),
 	}
 
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(response)
+	if err := json.NewEncoder(w).Encode(response); err != nil {
+		h.logger.Warn("failed to encode health response", "error", err)
+	}
 }
 
 // checkPermission checks if the user has the required permission
@@ -272,11 +283,9 @@ func (h *Handler) checkPermission(user *auth.User, permission string) bool {
 	}
 
 	// Admin has all permissions
-	for _, role := range user.Roles {
-		if role == "admin" {
+	if slices.Contains(user.Roles, "admin") {
 			return true
 		}
-	}
 
 	// Check specific permission
 	for perm, hasPerm := range user.Permissions {

internal/api/protocol.go

@@ -8,6 +8,15 @@ import (
 	"time"
 )
 
+// safeUint64FromTime safely converts time.Time to uint64 timestamp
+func safeUint64FromTime(t time.Time) uint64 {
+	unix := t.Unix()
+	if unix < 0 {
+		return 0
+	}
+	return uint64(unix)
+}
+
 var bufferPool = sync.Pool{
 	New: func() interface{} {
 		buf := make([]byte, 0, 256)
@@ -91,7 +100,7 @@ type ResponsePacket struct {
 func NewSuccessPacket(message string) *ResponsePacket {
 	return &ResponsePacket{
 		PacketType:     PacketTypeSuccess,
-		Timestamp:      uint64(time.Now().Unix()),
+		Timestamp:      safeUint64FromTime(time.Now()),
 		SuccessMessage: message,
 	}
 }
@@ -103,7 +112,7 @@ func NewSuccessPacketWithPayload(message string, payload interface{}) *ResponseP
 
 	return &ResponsePacket{
 		PacketType:     PacketTypeData,
-		Timestamp:      uint64(time.Now().Unix()),
+		Timestamp:      safeUint64FromTime(time.Now()),
 		SuccessMessage: message,
 		DataType:       "status",
 		DataPayload:    payloadBytes,
@@ -114,7 +123,7 @@ func NewSuccessPacketWithPayload(message string, payload interface{}) *ResponseP
 func NewErrorPacket(errorCode byte, message string, details string) *ResponsePacket {
 	return &ResponsePacket{
 		PacketType:   PacketTypeError,
-		Timestamp:    uint64(time.Now().Unix()),
+		Timestamp:    safeUint64FromTime(time.Now()),
 		ErrorCode:    errorCode,
 		ErrorMessage: message,
 		ErrorDetails: details,
@@ -130,7 +139,7 @@ func NewProgressPacket(
 ) *ResponsePacket {
 	return &ResponsePacket{
 		PacketType:      PacketTypeProgress,
-		Timestamp:       uint64(time.Now().Unix()),
+		Timestamp:       safeUint64FromTime(time.Now()),
 		ProgressType:    progressType,
 		ProgressValue:   value,
 		ProgressTotal:   total,
@@ -142,7 +151,7 @@ func NewProgressPacket(
 func NewStatusPacket(data string) *ResponsePacket {
 	return &ResponsePacket{
 		PacketType: PacketTypeStatus,
-		Timestamp:  uint64(time.Now().Unix()),
+		Timestamp:  safeUint64FromTime(time.Now()),
 		StatusData: data,
 	}
 }
@@ -151,7 +160,7 @@ func NewStatusPacket(data string) *ResponsePacket {
 func NewDataPacket(dataType string, payload []byte) *ResponsePacket {
 	return &ResponsePacket{
 		PacketType:  PacketTypeData,
-		Timestamp:   uint64(time.Now().Unix()),
+		Timestamp:   safeUint64FromTime(time.Now()),
 		DataType:    dataType,
 		DataPayload: payload,
 	}
@@ -161,7 +170,7 @@ func NewDataPacket(dataType string, payload []byte) *ResponsePacket {
 func NewLogPacket(level byte, message string) *ResponsePacket {
 	return &ResponsePacket{
 		PacketType: PacketTypeLog,
-		Timestamp:  uint64(time.Now().Unix()),
+		Timestamp:  safeUint64FromTime(time.Now()),
 		LogLevel:   level,
 		LogMessage: message,
 	}
@@ -236,18 +245,38 @@ func serializePacketToBuffer(p *ResponsePacket, buf []byte) ([]byte, error) {
 	return buf, nil
 }
 
+// uint16ToBytes extracts high and low bytes from uint16 safely
+func uint16ToBytes(v uint16) (high, low byte) {
+	var b [2]byte
+	binary.BigEndian.PutUint16(b[:], v)
+	return b[0], b[1]
+}
+
 // appendString writes a string with fixed 16-bit length prefix
 func appendString(buf []byte, s string) []byte {
-	length := uint16(len(s))
-	buf = append(buf, byte(length>>8), byte(length))
+	length := min(len(s), 65535)
+	// #nosec G115 -- length is bounded by min() to 65535, safe conversion
+	len16 := uint16(length)
+	high, low := uint16ToBytes(len16)
+	buf = append(buf, high, low)
 	buf = append(buf, s...)
 	return buf
 }
 
+// uint32ToBytes extracts 4 bytes from uint32 safely
+func uint32ToBytes(v uint32) [4]byte {
+	var b [4]byte
+	binary.BigEndian.PutUint32(b[:], v)
+	return b
+}
+
 // appendBytes writes bytes with fixed 32-bit length prefix
 func appendBytes(buf []byte, b []byte) []byte {
-	length := uint32(len(b))
-	buf = append(buf, byte(length>>24), byte(length>>16), byte(length>>8), byte(length))
+	length := min(len(b), 4294967295)
+	// #nosec G115 -- length is bounded by min() to max uint32, safe conversion
+	len32 := uint32(length)
+	bytes := uint32ToBytes(len32)
+	buf = append(buf, bytes[:]...)
 	buf = append(buf, b...)
 	return buf
 }

internal/api/responses/errors.go

@@ -84,7 +84,10 @@ func WriteError(w http.ResponseWriter, r *http.Request, status int, err error, l
 
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)
-	json.NewEncoder(w).Encode(resp)
+	if encodeErr := json.NewEncoder(w).Encode(resp); encodeErr != nil {
+		// Already wrote headers, can't do much about encoding errors
+		_ = encodeErr
+	}
 }
 
 // WriteErrorMessage writes a sanitized error response with a custom message.
@@ -112,7 +115,10 @@ func WriteErrorMessage(w http.ResponseWriter, r *http.Request, status int, messa
 
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)
-	json.NewEncoder(w).Encode(resp)
+	if encodeErr := json.NewEncoder(w).Encode(resp); encodeErr != nil {
+		// Already wrote headers, can't do much about encoding errors
+		_ = encodeErr
+	}
 }
 
 // sanitizeError removes potentially sensitive information from error messages.
@@ -137,6 +143,7 @@ func sanitizeError(msg string) string {
 	msg = strings.ReplaceAll(msg, "internal error", "an error occurred")
 	msg = strings.ReplaceAll(msg, "Internal Error", "an error occurred")
 
+	// TODO: This needs improvement, why is the length static? is there a better way to do this.
 	// Truncate if too long
 	if len(msg) > 200 {
 		msg = msg[:200] + "..."

internal/api/server_gen.go

@@ -137,10 +137,10 @@ type AuditEvent struct {
 	Error  *string `json:"error,omitempty"`
 
 	// EventHash This event's hash
-	EventHash *string                 `json:"event_hash,omitempty"`
-	EventType *AuditEventEventType    `json:"event_type,omitempty"`
-	IpAddress *string                 `json:"ip_address,omitempty"`
-	Metadata  *map[string]interface{} `json:"metadata,omitempty"`
+	EventHash *string              `json:"event_hash,omitempty"`
+	EventType *AuditEventEventType `json:"event_type,omitempty"`
+	IpAddress *string              `json:"ip_address,omitempty"`
+	Metadata  *map[string]any      `json:"metadata,omitempty"`
 
 	// PrevHash Previous event hash in chain
 	PrevHash *string `json:"prev_hash,omitempty"`

internal/api/spec_embed.go

@@ -19,6 +19,7 @@ func openAPISpecPath() string {
 // ServeOpenAPISpec serves the OpenAPI specification as YAML
 func ServeOpenAPISpec(w http.ResponseWriter, _ *http.Request) {
 	specPath := openAPISpecPath()
+	// #nosec G304 -- specPath is a hardcoded relative path, not from user input
 	data, err := os.ReadFile(specPath)
 	if err != nil {
 		http.Error(w, "Failed to read OpenAPI spec", http.StatusInternalServerError)

internal/api/validate/handlers.go

@@ -138,7 +138,7 @@ func (h *Handler) HandleGetValidateStatus(conn *websocket.Conn, validateID strin
 
 	// Stub implementation - in production, would query validation status from database
 
-	return h.sendSuccessPacket(conn, map[string]interface{}{
+	return h.sendSuccessPacket(conn, map[string]any{
 		"success":     true,
 		"validate_id": validateID,
 		"status":      "completed",
@@ -152,10 +152,10 @@ func (h *Handler) HandleListValidations(conn *websocket.Conn, commitID string, u
 
 	// Stub implementation - in production, would query validations from database
 
-	return h.sendSuccessPacket(conn, map[string]interface{}{
+	return h.sendSuccessPacket(conn, map[string]any{
 		"success":   true,
 		"commit_id": commitID,
-		"validations": []map[string]interface{}{
+		"validations": []map[string]any{
 			{
 				"validate_id": "val-001",
 				"status":      "completed",