first test

backend/models/ai_features.go

@@ -0,0 +1,193 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// AISummary represents an AI-generated summary
+type AISummary struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Source content
+	ContentType string `json:"content_type" gorm:"not null"` // "bookmark", "note", "file"
+	ContentID   uint   `json:"content_id" gorm:"not null"`
+
+	// Summary data
+	Title       string `json:"title"`
+	Summary     string `json:"summary" gorm:"type:text"`
+	KeyPoints   string `json:"key_points" gorm:"type:text"`   // JSON array of key points
+	Tags        string `json:"tags" gorm:"type:text"`        // JSON array of suggested tags
+	ReadTime    int    `json:"read_time"`                    // Estimated reading time in minutes
+	Complexity  string `json:"complexity" gorm:"default:'medium'"` // "low", "medium", "high"
+
+	// AI metadata
+	ModelUsed     string    `json:"model_used"`
+	ProcessingMs  int64     `json:"processing_ms"`
+	TokenCount    int       `json:"token_count"`
+	Confidence    float64   `json:"confidence"` // AI confidence score 0-1
+	LastAnalyzed  time.Time `json:"last_analyzed"`
+}
+
+// AITaskSuggestion represents AI-generated task suggestions
+type AITaskSuggestion struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Suggestion data
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description" gorm:"type:text"`
+	Priority    string `json:"priority" gorm:"default:'medium'"` // "low", "medium", "high", "urgent"
+	Category    string `json:"category"`                        // "work", "personal", "learning", "health", etc.
+	
+	// Context and reasoning
+	Reasoning     string `json:"reasoning" gorm:"type:text"`     // Why this task is suggested
+	ContextType   string `json:"context_type"`                   // "calendar", "bookmarks", "deadlines", "habits"
+	ContextData   string `json:"context_data" gorm:"type:text"`   // JSON data about context
+	Deadline      *time.Time `json:"deadline"`
+	EstimatedTime int    `json:"estimated_time"` // in minutes
+
+	// AI metadata
+	ModelUsed    string  `json:"model_used"`
+	Confidence   float64 `json:"confidence"` // AI confidence score 0-1
+	Accepted     bool    `json:"accepted" gorm:"default:false"`
+	Dismissed    bool    `json:"dismissed" gorm:"default:false"`
+}
+
+// AITagSuggestion represents AI-generated tag suggestions
+type AITagSuggestion struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Target content
+	ContentType string `json:"content_type" gorm:"not null"` // "bookmark", "note", "task", "file"
+	ContentID   uint   `json:"content_id" gorm:"not null"`
+
+	// Tag suggestions
+	SuggestedTags string `json:"suggested_tags" gorm:"type:text"` // JSON array of suggested tags
+	ExistingTags  string `json:"existing_tags" gorm:"type:text"`  // JSON array of current tags
+	Relevance     float64 `json:"relevance"`                     // Relevance score 0-1
+
+	// AI metadata
+	ModelUsed   string `json:"model_used"`
+	Confidence  float64 `json:"confidence"`
+	Applied     bool    `json:"applied" gorm:"default:false"`
+	Dismissed   bool    `json:"dismissed" gorm:"default:false"`
+}
+
+// AIContentGeneration represents AI-generated content
+type AIContentGeneration struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Generation request
+	Prompt      string `json:"prompt" gorm:"type:text"`
+	ContentType string `json:"content_type" gorm:"not null"` // "blog", "code", "email", "summary", "outline"
+	Context     string `json:"context" gorm:"type:text"`     // Additional context for generation
+
+	// Generated content
+	Title       string `json:"title"`
+	Content     string `json:"content" gorm:"type:text"`
+	WordCount   int    `json:"word_count"`
+	ReadTime    int    `json:"read_time"` // Estimated reading time in minutes
+
+	// AI metadata
+	ModelUsed     string  `json:"model_used"`
+	ProcessingMs  int64   `json:"processing_ms"`
+	TokenCount    int     `json:"token_count"`
+	Confidence    float64 `json:"confidence"`
+	Temperature   float64 `json:"temperature"`
+	Used          bool    `json:"used" gorm:"default:false"`
+	Rating        *int    `json:"rating"` // User rating 1-5
+	Feedback      string  `json:"feedback" gorm:"type:text"`
+}
+
+// AICodeReview represents AI code review analysis
+type AICodeReview struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Code context
+	RepositoryURL string `json:"repository_url"`
+	CommitHash    string `json:"commit_hash"`
+	FilePath      string `json:"file_path"`
+	PRNumber      int    `json:"pr_number"`
+	BranchName    string `json:"branch_name"`
+
+	// Review data
+	OriginalCode  string `json:"original_code" gorm:"type:text"`
+	Suggestions    string `json:"suggestions" gorm:"type:text"`    // JSON array of suggestions
+	Issues         string `json:"issues" gorm:"type:text"`         // JSON array of issues found
+	Score          int    `json:"score" gorm:"default:0"`          // Code quality score 0-100
+	SecurityIssues string `json:"security_issues" gorm:"type:text"` // JSON array of security issues
+	Performance    string `json:"performance" gorm:"type:text"`    // Performance suggestions
+
+	// AI metadata
+	ModelUsed    string  `json:"model_used"`
+	Confidence   float64 `json:"confidence"`
+	ProcessingMs int64   `json:"processing_ms"`
+	TokenCount   int     `json:"token_count"`
+	Applied      bool    `json:"applied" gorm:"default:false"`
+}
+
+// AILearningRecommendation represents AI-generated learning recommendations
+type AILearningRecommendation struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Recommendation data
+	Title           string `json:"title" gorm:"not null"`
+	Description     string `json:"description" gorm:"type:text"`
+	Category        string `json:"category"`        // "programming", "design", "business", etc.
+	Difficulty      string `json:"difficulty"`      // "beginner", "intermediate", "advanced"
+	EstimatedHours  int    `json:"estimated_hours"`  // Estimated time to complete
+	Prerequisites   string `json:"prerequisites" gorm:"type:text"` // JSON array of prerequisites
+	Resources       string `json:"resources" gorm:"type:text"`     // JSON array of learning resources
+	CourseID        *uint  `json:"course_id"`        // Link to existing course if applicable
+
+	// Personalization
+	Reasoning       string  `json:"reasoning" gorm:"type:text"` // Why this is recommended
+	RelevanceScore  float64 `json:"relevance_score"`           // How relevant to user 0-1
+	CareerImpact    string  `json:"career_impact"`             // Career impact description
+	SkillGained     string  `json:"skill_gained"`              // Primary skill gained
+
+	// AI metadata
+	ModelUsed    string  `json:"model_used"`
+	Confidence   float64 `json:"confidence"`
+	Started      bool    `json:"started" gorm:"default:false"`
+	Completed    bool    `json:"completed" gorm:"default:false"`
+	Rating       *int    `json:"rating"` // User rating 1-5
+	Feedback     string  `json:"feedback" gorm:"type:text"`
+}

backend/models/ai_recommendation.go

@@ -0,0 +1,153 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// AIRecommendation represents an AI-generated recommendation
+type AIRecommendation struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// User information
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Recommendation details
+	RecommendationType string `json:"recommendation_type" gorm:"not null;index"` // content, task, learning, connection
+	ContentType       string `json:"content_type" gorm:"index"`                // bookmark, note, task, course, user
+	ContentID         *uint `json:"content_id,omitempty" gorm:"index"`
+	Title             string `json:"title" gorm:"not null"`
+	Description       string `json:"description"`
+	Reasoning         string `json:"reasoning"` // Why this was recommended
+
+	// Content details (for display without additional queries)
+	ContentTitle   string `json:"content_title"`
+	ContentURL     string `json:"content_url"`
+	ContentPreview string `json:"content_preview"`
+	AuthorName     string `json:"author_name"`
+	Tags           string `json:"tags" gorm:"serializer:json"`
+
+	// Recommendation metadata
+	Confidence    float64 `json:"confidence" gorm:"default:0.0"` // 0.0 to 1.0
+	Priority      string  `json:"priority" gorm:"default:medium"` // low, medium, high
+	Category      string  `json:"category"`                       // productivity, learning, collaboration, etc.
+	ExpiresAt     *time.Time `json:"expires_at"`
+	Clicked       bool      `json:"clicked" gorm:"default:false"`
+	Dismissed     bool      `json:"dismissed" gorm:"default:false"`
+	ClickedAt     *time.Time `json:"clicked_at"`
+	DismissedAt   *time.Time `json:"dismissed_at"`
+
+	// Feedback
+	Feedback     string     `json:"feedback"` // helpful, not_helpful, irrelevant
+	FeedbackAt   *time.Time `json:"feedback_at"`
+	FeedbackText string     `json:"feedback_text"`
+
+	// Source information
+	SourceModel   string `json:"source_model"`   // Which AI model generated this
+	SourceVersion string `json:"source_version"` // Version of the recommendation engine
+	TrainingData  string `json:"training_data"`  // What data was used for training
+}
+
+// UserPreference represents user preferences for recommendations
+type UserPreference struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// User information
+	UserID uint `json:"user_id" gorm:"not null;uniqueIndex"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Recommendation preferences
+	EnableRecommendations    bool     `json:"enable_recommendations" gorm:"default:true"`
+	ContentRecommendations   bool     `json:"content_recommendations" gorm:"default:true"`
+	TaskRecommendations      bool     `json:"task_recommendations" gorm:"default:true"`
+	LearningRecommendations  bool     `json:"learning_recommendations" gorm:"default:true"`
+	ConnectionRecommendations bool     `json:"connection_recommendations" gorm:"default:false"`
+	
+	// Frequency and timing
+	MaxRecommendationsPerDay int      `json:"max_recommendations_per_day" gorm:"default:5"`
+	PreferredCategories      []string `json:"preferred_categories" gorm:"serializer:json"`
+	BlockedCategories        []string `json:"blocked_categories" gorm:"serializer:json"`
+	PreferredContentTypes    []string `json:"preferred_content_types" gorm:"serializer:json"`
+	
+	// Quality thresholds
+	MinConfidenceThreshold float64 `json:"min_confidence_threshold" gorm:"default:0.6"`
+	MaxAgeHours           int     `json:"max_age_hours" gorm:"default:168"` // 1 week
+
+	// Learning and adaptation
+	EnablePersonalization bool `json:"enable_personalization" gorm:"default:true"`
+	EnableFeedbackLearning bool `json:"enable_feedback_learning" gorm:"default:true"`
+	LastRecommendationAt   *time.Time `json:"last_recommendation_at"`
+}
+
+// RecommendationInteraction tracks user interactions with recommendations
+type RecommendationInteraction struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Related entities
+	UserID          uint              `json:"user_id" gorm:"not null;index"`
+	User            User              `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	RecommendationID uint             `json:"recommendation_id" gorm:"not null;index"`
+	Recommendation  AIRecommendation  `json:"recommendation,omitempty" gorm:"foreignKey:RecommendationID"`
+
+	// Interaction details
+	InteractionType string `json:"interaction_type" gorm:"not null;index"` // view, click, dismiss, feedback, share
+	InteractionData string `json:"interaction_data" gorm:"serializer:json"` // Additional context
+	Duration        int    `json:"duration"` // Time spent in seconds (for views)
+	Context         string `json:"context"`  // Where the interaction occurred (dashboard, search, etc.)
+
+	// Machine learning features
+	UserActivityBefore string `json:"user_activity_before"` // What user was doing before
+	UserActivityAfter  string `json:"user_activity_after"`  // What user did after
+	SessionID          string `json:"session_id"`
+	DeviceType         string `json:"device_type"`
+}
+
+// TableName returns the table name for AIRecommendation
+func (AIRecommendation) TableName() string {
+	return "ai_recommendations"
+}
+
+// TableName returns the table name for UserPreference
+func (UserPreference) TableName() string {
+	return "user_preferences"
+}
+
+// TableName returns the table name for RecommendationInteraction
+func (RecommendationInteraction) TableName() string {
+	return "recommendation_interactions"
+}
+
+// BeforeCreate hooks
+func (r *AIRecommendation) BeforeCreate(tx *gorm.DB) error {
+	if r.Priority == "" {
+		r.Priority = "medium"
+	}
+	if r.Confidence == 0 {
+		r.Confidence = 0.5
+	}
+	return nil
+}
+
+func (up *UserPreference) BeforeCreate(tx *gorm.DB) error {
+	if up.MaxRecommendationsPerDay == 0 {
+		up.MaxRecommendationsPerDay = 5
+	}
+	if up.MinConfidenceThreshold == 0 {
+		up.MinConfidenceThreshold = 0.6
+	}
+	if up.MaxAgeHours == 0 {
+		up.MaxAgeHours = 168 // 1 week
+	}
+	return nil
+}

backend/models/ai_settings.go

@@ -0,0 +1,62 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// UserAISettings stores user-specific AI provider configurations
+type UserAISettings struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;uniqueIndex"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Mistral Settings
+	MistralEnabled       *bool  `json:"mistral_enabled" gorm:"default:false"`
+	MistralAPIKey        string `json:"-" gorm:"column:mistral_api_key"` // Encrypted
+	MistralModel         string `json:"mistral_model" gorm:"default:mistral-small-latest"`
+	MistralModelThinking string `json:"mistral_model_thinking" gorm:"default:mistral-large-latest"`
+
+	// Grok Settings
+	GrokEnabled       *bool  `json:"grok_enabled" gorm:"default:false"`
+	GrokAPIKey        string `json:"-" gorm:"column:grok_api_key"` // Encrypted
+	GrokBaseURL       string `json:"grok_base_url" gorm:"default:https://api.x.ai/v1"`
+	GrokModel         string `json:"grok_model" gorm:"default:grok-4-1-fast-non-reasoning-latest"`
+	GrokModelThinking string `json:"grok_model_thinking" gorm:"default:grok-4-1-fast-reasoning-latest"`
+
+	// DeepSeek Settings
+	DeepSeekEnabled       *bool  `json:"deepseek_enabled" gorm:"default:false"`
+	DeepSeekAPIKey        string `json:"-" gorm:"column:deepseek_api_key"` // Encrypted
+	DeepSeekBaseURL       string `json:"deepseek_base_url" gorm:"default:https://api.deepseek.com"`
+	DeepSeekModel         string `json:"deepseek_model" gorm:"default:deepseek-chat"`
+	DeepSeekModelThinking string `json:"deepseek_model_thinking" gorm:"default:deepseek-reasoner"`
+
+	// Ollama Settings
+	OllamaEnabled       *bool  `json:"ollama_enabled" gorm:"default:false"`
+	OllamaBaseURL       string `json:"ollama_base_url" gorm:"default:http://localhost:11434"`
+	OllamaModel         string `json:"ollama_model" gorm:"default:llama3.1"`
+	OllamaModelThinking string `json:"ollama_model_thinking" gorm:"default:llama3.1"`
+
+	// LongCat Settings
+	LongCatEnabled               *bool  `json:"longcat_enabled" gorm:"default:false"`
+	LongCatAPIKey                string `json:"-" gorm:"column:longcat_api_key"` // Encrypted
+	LongCatBaseURL               string `json:"longcat_base_url" gorm:"default:https://api.longcat.chat"`
+	LongCatOpenAIEndpoint        string `json:"longcat_openai_endpoint" gorm:"default:https://api.longcat.chat/openai"`
+	LongCatAnthropicEndpoint     string `json:"longcat_anthropic_endpoint" gorm:"default:https://api.longcat.chat/anthropic"`
+	LongCatModel                 string `json:"longcat_model" gorm:"default:LongCat-Flash-Chat"`
+	LongCatModelThinking         string `json:"longcat_model_thinking" gorm:"default:LongCat-Flash-Thinking"`
+	LongCatModelThinkingUpgraded string `json:"longcat_model_thinking_upgraded" gorm:"default:LongCat-Flash-Thinking-2601"`
+	LongCatFormat                string `json:"longcat_format" gorm:"default:openai"`
+
+	// OpenRouter Settings
+	OpenRouterEnabled       *bool  `json:"openrouter_enabled" gorm:"default:false"`
+	OpenRouterAPIKey        string `json:"-" gorm:"column:openrouter_api_key"` // Encrypted
+	OpenRouterBaseURL       string `json:"openrouter_base_url" gorm:"default:https://openrouter.ai/api"`
+	OpenRouterModel         string `json:"openrouter_model" gorm:"default:openrouter/auto"`
+	OpenRouterModelThinking string `json:"openrouter_model_thinking" gorm:"default:openrouter/auto"`
+}

backend/models/analytics.go

@@ -0,0 +1,297 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// Analytics represents user analytics data
+type Analytics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Analytics data
+	Date              time.Time `json:"date" gorm:"not null;index"`
+	HoursTracked      float64   `json:"hours_tracked"`
+	TasksCompleted    int       `json:"tasks_completed"`
+	BookmarksAdded    int       `json:"bookmarks_added"`
+	NotesCreated      int       `json:"notes_created"`
+	CoursesStarted    int       `json:"courses_started"`
+	CoursesCompleted  int       `json:"courses_completed"`
+	GitHubCommits     int       `json:"github_commits"`
+	GitHubPRs         int       `json:"github_prs"`
+	StudyStreak       int       `json:"study_streak"`
+	ProductivityScore float64   `json:"productivity_score"`
+}
+
+// ProductivityMetrics represents productivity analytics
+type ProductivityMetrics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Productivity data
+	Period               string    `json:"period"` // daily, weekly, monthly, yearly
+	StartDate            time.Time `json:"start_date"`
+	EndDate              time.Time `json:"end_date"`
+	TotalHours           float64   `json:"total_hours"`
+	BillableHours        float64   `json:"billable_hours"`
+	NonBillableHours     float64   `json:"non_billable_hours"`
+	TasksCompleted       int       `json:"tasks_completed"`
+	AverageTaskTime      float64   `json:"average_task_time"`
+	PeakProductivityHour int       `json:"peak_productivity_hour"`
+	FocusScore           float64   `json:"focus_score"`
+	EfficiencyScore      float64   `json:"efficiency_score"`
+}
+
+// LearningAnalytics represents learning progress analytics
+type LearningAnalytics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Learning data
+	CourseID         uint       `json:"course_id" gorm:"not null;index"`
+	Course           Course     `json:"course,omitempty" gorm:"foreignKey:CourseID"`
+	StartDate        time.Time  `json:"start_date"`
+	LastAccessed     time.Time  `json:"last_accessed"`
+	TimeSpent        float64    `json:"time_spent"` // in hours
+	Progress         float64    `json:"progress"`   // percentage 0-100
+	ModulesCompleted int        `json:"modules_completed"`
+	TotalModules     int        `json:"total_modules"`
+	QuizScores       []float64  `json:"quiz_scores" gorm:"serializer:json"`
+	AverageScore     float64    `json:"average_score"`
+	StreakDays       int        `json:"streak_days"`
+	SkillsAcquired   []string   `json:"skills_acquired" gorm:"serializer:json"`
+	CourseCompleted  bool       `json:"course_completed" gorm:"default:false"`
+	CompletedAt      *time.Time `json:"completed_at,omitempty"`
+}
+
+// ContentAnalytics represents content consumption patterns
+type ContentAnalytics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Content data
+	ContentType     string    `json:"content_type"` // bookmark, note, file, task
+	ContentID       uint      `json:"content_id"`
+	FirstAccessed   time.Time `json:"first_accessed"`
+	LastAccessed    time.Time `json:"last_accessed"`
+	AccessCount     int       `json:"access_count"`
+	TimeSpent       float64   `json:"time_spent"` // in minutes
+	Tags            []Tag     `json:"tags,omitempty" gorm:"many2many:content_analytics_tags;"`
+	Category        string    `json:"category"`
+	Priority        string    `json:"priority"`
+	UsefulnessScore float64   `json:"usefulness_score"` // user-rated 1-5
+}
+
+// GitHubAnalytics represents GitHub contribution analytics
+type GitHubAnalytics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// GitHub data
+	Date          time.Time      `json:"date" gorm:"not null;index"`
+	Commits       int            `json:"commits"`
+	PullRequests  int            `json:"pull_requests"`
+	IssuesOpened  int            `json:"issues_opened"`
+	IssuesClosed  int            `json:"issues_closed"`
+	Reviews       int            `json:"reviews"`
+	Contributions int            `json:"contributions"`
+	Languages     map[string]int `json:"languages" gorm:"serializer:json"`
+	Repositories  []string       `json:"repositories" gorm:"serializer:json"`
+	ActivityScore float64        `json:"activity_score"`
+}
+
+// HabitAnalytics represents habit formation insights
+type HabitAnalytics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Habit data
+	HabitName      string    `json:"habit_name"`
+	StartDate      time.Time `json:"start_date"`
+	LastCompleted  time.Time `json:"last_completed"`
+	Streak         int       `json:"streak"`
+	BestStreak     int       `json:"best_streak"`
+	TotalDays      int       `json:"total_days"`
+	CompletionRate float64   `json:"completion_rate"`
+	Frequency      string    `json:"frequency"` // daily, weekly, monthly
+	Category       string    `json:"category"`  // productivity, learning, health, etc.
+	GoalTarget     int       `json:"goal_target"`
+	GoalAchieved   bool      `json:"goal_achieved"`
+}
+
+// Goal represents user goals for tracking
+type Goal struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Goal data
+	Title        string     `json:"title" gorm:"not null"`
+	Description  string     `json:"description"`
+	Category     string     `json:"category"` // learning, productivity, health, career
+	TargetValue  float64    `json:"target_value"`
+	CurrentValue float64    `json:"current_value"`
+	Unit         string     `json:"unit"`
+	Deadline     time.Time  `json:"deadline"`
+	Status       string     `json:"status"`   // active, completed, paused, cancelled
+	Priority     string     `json:"priority"` // low, medium, high, urgent
+	Progress     float64    `json:"progress"` // percentage 0-100
+	IsCompleted  bool       `json:"is_completed" gorm:"default:false"`
+	CompletedAt  *time.Time `json:"completed_at,omitempty"`
+
+	// Relationships
+	Milestones []Milestone `json:"milestones,omitempty" gorm:"foreignKey:GoalID"`
+}
+
+// Milestone represents goal milestones
+type Milestone struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	GoalID uint `json:"goal_id" gorm:"not null;index"`
+	Goal   Goal `json:"goal,omitempty" gorm:"foreignKey:GoalID"`
+
+	// Milestone data
+	Title        string     `json:"title" gorm:"not null"`
+	Description  string     `json:"description"`
+	TargetValue  float64    `json:"target_value"`
+	CurrentValue float64    `json:"current_value"`
+	Deadline     time.Time  `json:"deadline"`
+	Status       string     `json:"status"` // pending, completed, overdue
+	IsCompleted  bool       `json:"is_completed" gorm:"default:false"`
+	CompletedAt  *time.Time `json:"completed_at,omitempty"`
+	Order        int        `json:"order"`
+}
+
+// AnalyticsReport represents a comprehensive analytics report
+type AnalyticsReport struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Report data
+	ReportType      string                 `json:"report_type"` // daily, weekly, monthly, yearly, custom
+	StartDate       time.Time              `json:"start_date"`
+	EndDate         time.Time              `json:"end_date"`
+	Title           string                 `json:"title"`
+	Summary         string                 `json:"summary"`
+	Data            map[string]interface{} `json:"data" gorm:"serializer:json"`
+	Insights        []string               `json:"insights" gorm:"serializer:json"`
+	Recommendations []string               `json:"recommendations" gorm:"serializer:json"`
+	ShareableLink   string                 `json:"shareable_link"`
+	IsPublic        bool                   `json:"is_public" gorm:"default:false"`
+}
+
+// BeforeCreate hooks for default values
+func (a *Analytics) BeforeCreate(tx *gorm.DB) error {
+	if a.Date.IsZero() {
+		a.Date = time.Now().Truncate(24 * time.Hour)
+	}
+	return nil
+}
+
+func (p *ProductivityMetrics) BeforeCreate(tx *gorm.DB) error {
+	if p.StartDate.IsZero() {
+		p.StartDate = time.Now().Truncate(24 * time.Hour)
+	}
+	if p.EndDate.IsZero() {
+		p.EndDate = p.StartDate.Add(24 * time.Hour)
+	}
+	return nil
+}
+
+func (l *LearningAnalytics) BeforeCreate(tx *gorm.DB) error {
+	if l.StartDate.IsZero() {
+		l.StartDate = time.Now()
+	}
+	if l.LastAccessed.IsZero() {
+		l.LastAccessed = time.Now()
+	}
+	return nil
+}
+
+func (c *ContentAnalytics) BeforeCreate(tx *gorm.DB) error {
+	if c.FirstAccessed.IsZero() {
+		c.FirstAccessed = time.Now()
+	}
+	if c.LastAccessed.IsZero() {
+		c.LastAccessed = time.Now()
+	}
+	if c.AccessCount == 0 {
+		c.AccessCount = 1
+	}
+	return nil
+}
+
+func (g *GitHubAnalytics) BeforeCreate(tx *gorm.DB) error {
+	if g.Date.IsZero() {
+		g.Date = time.Now().Truncate(24 * time.Hour)
+	}
+	return nil
+}
+
+func (h *HabitAnalytics) BeforeCreate(tx *gorm.DB) error {
+	if h.StartDate.IsZero() {
+		h.StartDate = time.Now()
+	}
+	return nil
+}
+
+func (g *Goal) BeforeCreate(tx *gorm.DB) error {
+	if g.Status == "" {
+		g.Status = "active"
+	}
+	if g.Priority == "" {
+		g.Priority = "medium"
+	}
+	return nil
+}
+
+func (m *Milestone) BeforeCreate(tx *gorm.DB) error {
+	if m.Status == "" {
+		m.Status = "pending"
+	}
+	return nil
+}

backend/models/audit_log.go

@@ -0,0 +1,105 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// AuditAction represents the type of action performed
+type AuditAction string
+
+const (
+	AuditActionCreate    AuditAction = "create"
+	AuditActionRead      AuditAction = "read"
+	AuditActionUpdate    AuditAction = "update"
+	AuditActionDelete    AuditAction = "delete"
+	AuditActionLogin     AuditAction = "login"
+	AuditActionLogout    AuditAction = "logout"
+	AuditActionLoginFail AuditAction = "login_failed"
+	AuditActionExport    AuditAction = "export"
+	AuditActionImport    AuditAction = "import"
+	AuditActionEnable    AuditAction = "enable"
+	AuditActionDisable   AuditAction = "disable"
+	AuditActionUpload    AuditAction = "upload"
+	AuditActionDownload  AuditAction = "download"
+	AuditActionShare     AuditAction = "share"
+	AuditActionAccess    AuditAction = "access"
+)
+
+// AuditResource represents the resource type
+type AuditResource string
+
+const (
+	AuditResourceUser         AuditResource = "user"
+	AuditResourceNote         AuditResource = "note"
+	AuditResourceFile         AuditResource = "file"
+	AuditResourceBookmark     AuditResource = "bookmark"
+	AuditResourceTask         AuditResource = "task"
+	AuditResourceTimeEntry    AuditResource = "time_entry"
+	AuditResourceIntegration  AuditResource = "integration"
+	AuditResourceTeam         AuditResource = "team"
+	AuditResourceGoal         AuditResource = "goal"
+	AuditResourceHabit        AuditResource = "habit"
+	AuditResourceCalendar     AuditResource = "calendar"
+	AuditResourceSearch       AuditResource = "search"
+	AuditResourceAI           AuditResource = "ai"
+	AuditResourceAnalytics    AuditResource = "analytics"
+	AuditResourceSecurity     AuditResource = "security"
+	AuditResourceSystem       AuditResource = "system"
+)
+
+// AuditLog represents an audit log entry
+type AuditLog struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// User information
+	UserID      uint   `json:"user_id" gorm:"not null;index"`
+	User        User   `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	UserEmail   string `json:"user_email" gorm:"not null"`
+	UserIP      string `json:"user_ip"`
+	UserAgent   string `json:"user_agent"`
+
+	// Action information
+	Action      AuditAction   `json:"action" gorm:"not null;index"`
+	Resource    AuditResource `json:"resource" gorm:"not null;index"`
+	ResourceID  *uint         `json:"resource_id,omitempty" gorm:"index"`
+
+	// Details
+	Description string                 `json:"description"`
+	Details     map[string]interface{} `json:"details" gorm:"serializer:json"`
+	OldValues   map[string]interface{} `json:"old_values" gorm:"serializer:json"`
+	NewValues   map[string]interface{} `json:"new_values" gorm:"serializer:json"`
+
+	// Security context
+	SessionID   string `json:"session_id"`
+	Success     bool   `json:"success" gorm:"default:true"`
+	FailureReason string `json:"failure_reason"`
+
+	// Geographic and device info
+	Country     string `json:"country"`
+	City        string `json:"city"`
+	Device      string `json:"device"`
+	Platform    string `json:"platform"`
+	Browser     string `json:"browser"`
+
+	// Risk assessment
+	RiskLevel   string `json:"risk_level" gorm:"default:low"` // low, medium, high, critical
+	Suspicious  bool   `json:"suspicious" gorm:"default:false"`
+}
+
+// TableName returns the table name for AuditLog
+func (AuditLog) TableName() string {
+	return "audit_logs"
+}
+
+// BeforeCreate hook to set default values
+func (a *AuditLog) BeforeCreate(tx *gorm.DB) error {
+	if a.RiskLevel == "" {
+		a.RiskLevel = "low"
+	}
+	return nil
+}

backend/models/bookmark.go

@@ -19,21 +19,21 @@ type Bookmark struct {
 	Title       string `json:"title" gorm:"not null"`
 	URL         string `json:"url" gorm:"not null"`
 	Description string `json:"description"`
-	
+
 	// Organization
-	Tags  []Tag `json:"tags,omitempty" gorm:"many2many:bookmark_tags;"`
-	
+	Tags []Tag `json:"tags,omitempty" gorm:"many2many:bookmark_tags;"`
+
 	// Metadata
 	Favicon    string `json:"favicon"`
 	Screenshot string `json:"screenshot"`
 	IsRead     bool   `json:"is_read" gorm:"default:false"`
 	IsFavorite bool   `json:"is_favorite" gorm:"default:false"`
-	
+
 	// Content extraction
-	Content     string `json:"content"`
-	Author      string `json:"author"`
+	Content     string     `json:"content"`
+	Author      string     `json:"author"`
 	PublishedAt *time.Time `json:"published_at"`
-	
+
 	// Reading tracking
 	ReadAt *time.Time `json:"read_at"`
 }

backend/models/calendar.go

@@ -0,0 +1,170 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// CalendarEvent represents an event in the calendar
+type CalendarEvent struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description"`
+	
+	// Timing
+	StartTime time.Time `json:"start_time" gorm:"not null"`
+	EndTime   time.Time `json:"end_time" gorm:"not null"`
+	
+	// Classification
+	Type     string `json:"type" gorm:"default:'reminder'"` // task, meeting, deadline, reminder, habit
+	Priority string `json:"priority" gorm:"default:'medium'"` // low, medium, high, urgent
+	
+	// Location and attendees
+	Location  string `json:"location"`
+	Attendees string `json:"attendees"` // JSON string of attendee emails/names
+	
+	// Recurrence
+	Recurring bool   `json:"recurring" gorm:"default:false"`
+	Rrule     string `json:"rrule"` // RRULE format for recurrence
+	
+	// Source integration
+	Source string `json:"source" gorm:"default:'trackeep'"` // trackeep, google, outlook, manual
+	
+	// Associations
+	TaskID     *uint    `json:"task_id,omitempty"`
+	Task       *Task    `json:"task,omitempty" gorm:"foreignKey:TaskID"`
+	BookmarkID *uint    `json:"bookmark_id,omitempty"`
+	Bookmark   *Bookmark `json:"bookmark,omitempty" gorm:"foreignKey:BookmarkID"`
+	NoteID     *uint    `json:"note_id,omitempty"`
+	Note       *Note    `json:"note,omitempty" gorm:"foreignKey:NoteID"`
+	
+	// Status
+	IsCompleted bool `json:"is_completed" gorm:"default:false"`
+	IsAllDay    bool `json:"is_all_day" gorm:"default:false"`
+	
+	// Notifications
+	ReminderMinutes int `json:"reminder_minutes"` // Minutes before event to remind
+}
+
+// RecurrenceRule represents recurrence patterns for events
+type RecurrenceRule struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	Frequency string `json:"frequency" gorm:"not null"` // daily, weekly, monthly, yearly
+	Interval  int    `json:"interval" gorm:"default:1"`  // Every N days/weeks/months/years
+	
+	// End conditions
+	EndDate    *time.Time `json:"end_date"`
+	Count      *int       `json:"count"`      // Number of occurrences
+	IsForever  bool       `json:"is_forever" gorm:"default:false"`
+	
+	// Weekly specifics
+	DaysOfWeek string `json:"days_of_week"` // JSON array: [0,1,2,3,4,5,6] where 0=Sunday
+	
+	// Monthly specifics
+	DayOfMonth     *int `json:"day_of_month"`      // 1-31
+	WeekOfMonth    *int `json:"week_of_month"`     // 1-5 (first to fifth week)
+	DayOfWeek      *int `json:"day_of_week"`       // 0-6 (Sunday to Saturday)
+	
+	// Event association
+	EventID uint `json:"event_id" gorm:"not null"`
+	Event   CalendarEvent `json:"event,omitempty" gorm:"foreignKey:EventID"`
+}
+
+// CalendarSettings represents user calendar preferences
+type CalendarSettings struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;uniqueIndex"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	
+	// Display preferences
+	DefaultView     string `json:"default_view" gorm:"default:'week'"` // month, week, day
+	WeekStartsOn    int    `json:"week_starts_on" gorm:"default:0"`   // 0=Sunday, 1=Monday
+	Timezone        string `json:"timezone" gorm:"default:'UTC'"`
+	TimeFormat24Hour bool   `json:"time_format_24_hour" gorm:"default:true"`
+	
+	// Integration settings
+	GoogleCalendarEnabled bool   `json:"google_calendar_enabled" gorm:"default:false"`
+	GoogleCalendarToken   string `json:"google_calendar_token"`
+	OutlookEnabled        bool   `json:"outlook_enabled" gorm:"default:false"`
+	OutlookToken          string `json:"outlook_token"`
+	
+	// Notification settings
+	DefaultReminderMinutes int  `json:"default_reminder_minutes" gorm:"default:15"`
+	EmailRemindersEnabled bool  `json:"email_reminders_enabled" gorm:"default:true"`
+	PushRemindersEnabled  bool  `json:"push_reminders_enabled" gorm:"default:true"`
+}
+
+// GetDuration returns the duration of the event
+func (e *CalendarEvent) GetDuration() time.Duration {
+	return e.EndTime.Sub(e.StartTime)
+}
+
+// IsOverdue checks if the event is overdue
+func (e *CalendarEvent) IsOverdue() bool {
+	return !e.IsCompleted && time.Now().After(e.EndTime)
+}
+
+// IsToday checks if the event occurs today
+func (e *CalendarEvent) IsToday() bool {
+	now := time.Now()
+	return e.StartTime.Year() == now.Year() &&
+		e.StartTime.Month() == now.Month() &&
+		e.StartTime.Day() == now.Day()
+}
+
+// IsUpcoming checks if the event is in the next 7 days
+func (e *CalendarEvent) IsUpcoming() bool {
+	now := time.Now()
+	weekLater := now.AddDate(0, 0, 7)
+	return e.StartTime.After(now) && e.StartTime.Before(weekLater)
+}
+
+// GetPriorityColor returns a color based on priority
+func (e *CalendarEvent) GetPriorityColor() string {
+	switch e.Priority {
+	case "urgent":
+		return "#ef4444" // red
+	case "high":
+		return "#f97316" // orange
+	case "medium":
+		return "#eab308" // yellow
+	case "low":
+		return "#22c55e" // green
+	default:
+		return "#6b7280" // gray
+	}
+}
+
+// GetTypeColor returns a color based on event type
+func (e *CalendarEvent) GetTypeColor() string {
+	switch e.Type {
+	case "task":
+		return "#3b82f6" // blue
+	case "meeting":
+		return "#8b5cf6" // purple
+	case "deadline":
+		return "#ef4444" // red
+	case "reminder":
+		return "#06b6d4" // cyan
+	case "habit":
+		return "#10b981" // emerald
+	default:
+		return "#6b7280" // gray
+	}
+}

backend/models/chat.go

@@ -0,0 +1,56 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// ChatMessage represents a chat message in the AI conversation
+type ChatMessage struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Content string `json:"content" gorm:"not null"`
+	Role    string `json:"role" gorm:"not null"` // "user" or "assistant"
+
+	// Session tracking
+	SessionID string `json:"session_id" gorm:"not null;index"`
+
+	// Metadata
+	TokenCount    int       `json:"token_count"`
+	ModelUsed     string    `json:"model_used"`
+	ProcessingMs  int64     `json:"processing_ms"`
+	ContextItems  []string  `json:"context_items" gorm:"serializer:json"` // IDs of referenced items
+}
+
+// ChatSession represents a chat session
+type ChatSession struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Title string `json:"title"`
+	
+	// Session metadata
+	MessageCount int       `json:"message_count" gorm:"default:0"`
+	LastMessageAt *time.Time `json:"last_message_at"`
+	
+	// Context configuration
+	IncludeBookmarks bool `json:"include_bookmarks" gorm:"default:true"`
+	IncludeTasks     bool `json:"include_tasks" gorm:"default:true"`
+	IncludeFiles     bool `json:"include_files" gorm:"default:true"`
+	IncludeNotes     bool `json:"include_notes" gorm:"default:true"`
+	
+	// Relationships
+	Messages []ChatMessage `json:"messages,omitempty" gorm:"foreignKey:SessionID"`
+}

backend/models/community.go

@@ -0,0 +1,444 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// Challenge represents a community challenge
+type Challenge struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Creator information
+	CreatorID uint `json:"creator_id" gorm:"not null;index"`
+	Creator   User `json:"creator,omitempty" gorm:"foreignKey:CreatorID"`
+
+	// Basic information
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description" gorm:"type:text"`
+	Category    string `json:"category" gorm:"not null"` // learning, productivity, fitness, creativity, technical
+
+	// Challenge details
+	Difficulty    string `json:"difficulty" gorm:"not null"` // beginner, intermediate, advanced, expert
+	Duration      int    `json:"duration" gorm:"not null"`   // Duration in days
+	Requirements  string `json:"requirements" gorm:"type:text"`
+	Rewards       string `json:"rewards" gorm:"type:text"`
+	Rules         string `json:"rules" gorm:"type:text"`
+
+	// Timeline
+	StartDate time.Time `json:"start_date"`
+	EndDate   time.Time `json:"end_date"`
+
+	// Participation settings
+	MaxParticipants *int `json:"max_participants,omitempty"` // nil for unlimited
+	IsTeamChallenge bool `json:"is_team_challenge" gorm:"default:false"`
+	TeamSize        int  `json:"team_size" gorm:"default:1"`
+
+	// Status and visibility
+	Status     string `json:"status" gorm:"default:draft"` // draft, active, completed, cancelled
+	IsPublic   bool   `json:"is_public" gorm:"default:true"`
+	IsFeatured bool   `json:"is_featured" gorm:"default:false"`
+
+	// Tags and metadata
+	Tags        []ChallengeTag `json:"tags,omitempty" gorm:"many2many:challenge_tags;"`
+	Image       string         `json:"image"`       // Challenge banner/image
+	Badge       string         `json:"badge"`       // Completion badge
+
+	// Analytics
+	ParticipantCount int       `json:"participant_count" gorm:"default:0"`
+	CompletionCount  int       `json:"completion_count" gorm:"default:0"`
+	CompletionRate   float64   `json:"completion_rate" gorm:"default:0"`
+	LastActivityAt   *time.Time `json:"last_activity_at,omitempty"`
+
+	// Relationships
+	Participants []ChallengeParticipant `json:"participants,omitempty" gorm:"foreignKey:ChallengeID"`
+	Milestones   []ChallengeMilestone   `json:"milestones,omitempty" gorm:"foreignKey:ChallengeID"`
+	Resources    []ChallengeResource    `json:"resources,omitempty" gorm:"foreignKey:ChallengeID"`
+}
+
+// ChallengeParticipant represents a user's participation in a challenge
+type ChallengeParticipant struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Participation information
+	ChallengeID uint `json:"challenge_id" gorm:"not null;index"`
+	Challenge   Challenge `json:"challenge,omitempty" gorm:"foreignKey:ChallengeID"`
+	UserID      uint `json:"user_id" gorm:"not null;index"`
+	User        User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Team information (for team challenges)
+	TeamID   *uint            `json:"team_id,omitempty"`
+	Team     *ChallengeTeam   `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	Role     string           `json:"role" gorm:"default:participant"` // participant, team_leader
+
+	// Progress tracking
+	Status        string     `json:"status" gorm:"default:joined"` // joined, in_progress, completed, dropped_out
+	Progress      float64    `json:"progress" gorm:"default:0"`    // Progress percentage (0-100)
+	StartedAt     *time.Time `json:"started_at,omitempty"`
+	CompletedAt   *time.Time `json:"completed_at,omitempty"`
+	DroppedOutAt  *time.Time `json:"dropped_out_at,omitempty"`
+
+	// Performance metrics
+	Score         int       `json:"score" gorm:"default:0"`
+	Rank          int       `json:"rank"`
+	BadgeEarned   bool      `json:"badge_earned" gorm:"default:false"`
+	LastActivityAt *time.Time `json:"last_activity_at,omitempty"`
+
+	// Notes and reflection
+	Notes         string `json:"notes" gorm:"type:text"`
+	Reflection    string `json:"reflection" gorm:"type:text"`
+}
+
+// ChallengeTeam represents a team in a team challenge
+type ChallengeTeam struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Team information
+	ChallengeID uint     `json:"challenge_id" gorm:"not null;index"`
+	Challenge   Challenge `json:"challenge,omitempty" gorm:"foreignKey:ChallengeID"`
+	Name        string   `json:"name" gorm:"not null"`
+	Description string   `json:"description" gorm:"type:text"`
+	Avatar      string   `json:"avatar"`
+
+	// Team settings
+	IsPrivate  bool `json:"is_private" gorm:"default:false"`
+	MaxMembers int  `json:"max_members" gorm:"default:5"`
+
+	// Team progress
+	Status        string     `json:"status" gorm:"default:active"` // active, completed, disbanded
+	Progress      float64    `json:"progress" gorm:"default:0"`
+	Score         int        `json:"score" gorm:"default:0"`
+	Rank          int        `json:"rank"`
+	CompletedAt   *time.Time `json:"completed_at,omitempty"`
+	LastActivityAt *time.Time `json:"last_activity_at,omitempty"`
+
+	// Relationships
+	LeaderID uint `json:"leader_id" gorm:"not null"`
+	Leader   User `json:"leader,omitempty" gorm:"foreignKey:LeaderID"`
+	Members  []ChallengeParticipant `json:"members,omitempty" gorm:"foreignKey:TeamID"`
+}
+
+// ChallengeMilestone represents a milestone in a challenge
+type ChallengeMilestone struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Milestone information
+	ChallengeID uint     `json:"challenge_id" gorm:"not null;index"`
+	Challenge   Challenge `json:"challenge,omitempty" gorm:"foreignKey:ChallengeID"`
+	Title       string   `json:"title" gorm:"not null"`
+	Description string   `json:"description" gorm:"type:text"`
+
+	// Milestone details
+	Order         int       `json:"order" gorm:"not null"` // Order in the challenge
+	TargetValue   float64   `json:"target_value" gorm:"not null"`
+	Unit          string    `json:"unit"` // days, points, hours, etc.
+	Deadline      time.Time `json:"deadline"`
+	PointsAwarded int       `json:"points_awarded" gorm:"default:0"`
+
+	// Status
+	IsActive bool `json:"is_active" gorm:"default:true"`
+
+	// Relationships
+	Completions []ChallengeMilestoneCompletion `json:"completions,omitempty" gorm:"foreignKey:MilestoneID"`
+}
+
+// ChallengeMilestoneCompletion represents a user's completion of a milestone
+type ChallengeMilestoneCompletion struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Completion information
+	MilestoneID uint `json:"milestone_id" gorm:"not null;index"`
+	Milestone   ChallengeMilestone `json:"milestone,omitempty" gorm:"foreignKey:MilestoneID"`
+	UserID      uint `json:"user_id" gorm:"not null;index"`
+	User        User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	TeamID      *uint `json:"team_id,omitempty"`
+
+	// Completion details
+	CompletedAt time.Time `json:"completed_at"`
+	Notes       string    `json:"notes" gorm:"type:text"`
+	Evidence    string    `json:"evidence" gorm:"type:text"` // Proof of completion
+	PointsEarned int       `json:"points_earned"`
+}
+
+// ChallengeResource represents a resource for a challenge
+type ChallengeResource struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Resource information
+	ChallengeID uint     `json:"challenge_id" gorm:"not null;index"`
+	Challenge   Challenge `json:"challenge,omitempty" gorm:"foreignKey:ChallengeID"`
+	Title       string   `json:"title" gorm:"not null"`
+	Description string   `json:"description" gorm:"type:text"`
+	URL         string   `json:"url"`
+	Type        string   `json:"type" gorm:"not null"` // article, video, tool, template, guide
+
+	// Resource details
+	Order      int    `json:"order" gorm:"default:0"`
+	IsRequired bool   `json:"is_required" gorm:"default:false"`
+	Duration   int    `json:"duration"` // Estimated duration in minutes
+	Tags       string `json:"tags"`     // Comma-separated tags
+}
+
+// ChallengeTag represents tags for challenges
+type ChallengeTag struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	Name        string `json:"name" gorm:"uniqueIndex;not null"`
+	Description string `json:"description"`
+	Color       string `json:"color" gorm:"default:#10b981"` // Tag color
+	UsageCount  int    `json:"usage_count" gorm:"default:0"`
+}
+
+// Mentorship represents a mentorship relationship
+type Mentorship struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Participants
+	MentorID uint `json:"mentor_id" gorm:"not null;index"`
+	Mentor   User `json:"mentor,omitempty" gorm:"foreignKey:MentorID"`
+	MenteeID uint `json:"mentee_id" gorm:"not null;index"`
+	Mentee   User `json:"mentee,omitempty" gorm:"foreignKey:MenteeID"`
+
+	// Mentorship details
+	Category    string `json:"category" gorm:"not null"` // career, technical, business, personal
+	Description string `json:"description" gorm:"type:text"`
+	Goals       string `json:"goals" gorm:"type:text"`
+
+	// Timeline
+	StartDate time.Time `json:"start_date"`
+	EndDate   *time.Time `json:"end_date,omitempty"`
+
+	// Status and settings
+	Status       string `json:"status" gorm:"default:pending"` // pending, active, paused, completed, terminated
+	IsPaid       bool   `json:"is_paid" gorm:"default:false"`
+	Rate         float64 `json:"rate" gorm:"default:0"` // Hourly rate or monthly rate
+	Currency     string `json:"currency" gorm:"default:USD"`
+	SessionLimit int    `json:"session_limit" gorm:"default:0"` // 0 for unlimited
+
+	// Matching preferences
+	MentorPreferences string `json:"mentor_preferences" gorm:"type:text"`
+	MenteePreferences string `json:"mentee_preferences" gorm:"type:text"`
+
+	// Analytics
+	SessionCount    int       `json:"session_count" gorm:"default:0"`
+	TotalHours     float64   `json:"total_hours" gorm:"default:0"`
+	LastSessionAt  *time.Time `json:"last_session_at,omitempty"`
+	SatisfactionScore float64 `json:"satisfaction_score" gorm:"default:0"` // 1-5 rating
+
+	// Relationships
+	Sessions    []MentorshipSession    `json:"sessions,omitempty" gorm:"foreignKey:MentorshipID"`
+	Reviews     []MentorshipReview     `json:"reviews,omitempty" gorm:"foreignKey:MentorshipID"`
+	Milestones  []MentorshipMilestone  `json:"milestones,omitempty" gorm:"foreignKey:MentorshipID"`
+}
+
+// MentorshipSession represents a mentoring session
+type MentorshipSession struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Session information
+	MentorshipID uint        `json:"mentorship_id" gorm:"not null;index"`
+	Mentorship   Mentorship   `json:"mentorship,omitempty" gorm:"foreignKey:MentorshipID"`
+	ScheduledFor time.Time   `json:"scheduled_for"`
+	Duration     int         `json:"duration"` // Duration in minutes
+	Status       string      `json:"status" gorm:"default:scheduled"` // scheduled, completed, cancelled, no_show
+
+	// Session details
+	Title       string `json:"title"`
+	Agenda      string `json:"agenda" gorm:"type:text"`
+	Notes       string `json:"notes" gorm:"type:text"`
+	RecordingURL string `json:"recording_url"`
+	Materials   string `json:"materials" gorm:"type:text"`
+
+	// Completion details
+	CompletedAt   *time.Time `json:"completed_at,omitempty"`
+	MentorNotes   string     `json:"mentor_notes" gorm:"type:text"`
+	MenteeNotes   string     `json:"mentee_notes" gorm:"type:text"`
+	ActionItems   string     `json:"action_items" gorm:"type:text"`
+	NextSteps     string     `json:"next_steps" gorm:"type:text"`
+
+	// Feedback
+	MentorRating   *int   `json:"mentor_rating,omitempty"`   // 1-5 rating from mentee
+	MenteeRating   *int   `json:"mentee_rating,omitempty"`   // 1-5 rating from mentor
+	MentorFeedback string `json:"mentor_feedback" gorm:"type:text"`
+	MenteeFeedback string `json:"mentee_feedback" gorm:"type:text"`
+}
+
+// MentorshipReview represents a review for a mentorship
+type MentorshipReview struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Review information
+	MentorshipID uint      `json:"mentorship_id" gorm:"not null;index"`
+	Mentorship   Mentorship `json:"mentorship,omitempty" gorm:"foreignKey:MentorshipID"`
+	ReviewerID   uint      `json:"reviewer_id" gorm:"not null;index"`
+	Reviewer     User      `json:"reviewer,omitempty" gorm:"foreignKey:ReviewerID"`
+	TargetID     uint      `json:"target_id" gorm:"not null;index"` // The person being reviewed
+	Target       User      `json:"target,omitempty" gorm:"foreignKey:TargetID"`
+
+	// Review content
+	Rating      int    `json:"rating" gorm:"not null;check:rating >= 1 AND rating <= 5"` // 1-5 stars
+	Title       string `json:"title"`
+	Content     string `json:"content" gorm:"type:text"`
+	IsPublic    bool   `json:"is_public" gorm:"default:false"`
+	IsVerified  bool   `json:"is_verified" gorm:"default:false"` // Verified mentorship
+
+	// Review metadata
+	HelpfulCount int `json:"helpful_count" gorm:"default:0"`
+	ReviewType   string `json:"review_type" gorm:"not null"` // mentor_review, mentee_review
+}
+
+// MentorshipMilestone represents a milestone in a mentorship
+type MentorshipMilestone struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Milestone information
+	MentorshipID uint      `json:"mentorship_id" gorm:"not null;index"`
+	Mentorship   Mentorship `json:"mentorship,omitempty" gorm:"foreignKey:MentorshipID"`
+	Title        string    `json:"title" gorm:"not null"`
+	Description  string    `json:"description" gorm:"type:text"`
+
+	// Milestone details
+	TargetDate   time.Time `json:"target_date"`
+	CompletedAt  *time.Time `json:"completed_at,omitempty"`
+	Status       string    `json:"status" gorm:"default:pending"` // pending, completed, overdue
+	Priority     string    `json:"priority" gorm:"default:medium"` // low, medium, high
+
+	// Progress tracking
+	Progress     float64 `json:"progress" gorm:"default:0"` // 0-100
+	Evidence     string  `json:"evidence" gorm:"type:text"`
+	Notes        string  `json:"notes" gorm:"type:text"`
+}
+
+// MentorshipRequest represents a mentorship request
+type MentorshipRequest struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Request information
+	FromUserID uint `json:"from_user_id" gorm:"not null;index"`
+	FromUser   User `json:"from_user,omitempty" gorm:"foreignKey:FromUserID"`
+	ToUserID   uint `json:"to_user_id" gorm:"not null;index"`
+	ToUser     User `json:"to_user,omitempty" gorm:"foreignKey:ToUserID"`
+
+	// Request details
+	Role         string `json:"role" gorm:"not null"` // mentor, mentee
+	Category     string `json:"category" gorm:"not null"`
+	Description  string `json:"description" gorm:"type:text"`
+	Goals        string `json:"goals" gorm:"type:text"`
+	Availability string `json:"availability" gorm:"type:text"`
+	Duration     int    `json:"duration"` // Desired duration in months
+	IsPaid       bool   `json:"is_paid"`
+	Rate         float64 `json:"rate"`
+	Currency     string `json:"currency" gorm:"default:USD"`
+
+	// Status
+	Status       string     `json:"status" gorm:"default:pending"` // pending, accepted, rejected, withdrawn
+	RespondedAt  *time.Time `json:"responded_at,omitempty"`
+	Response     string     `json:"response" gorm:"type:text"`
+
+	// Matching score (calculated by matching algorithm)
+	MatchScore   float64 `json:"match_score" gorm:"default:0"`
+	MatchReasons string  `json:"match_reasons" gorm:"type:text"`
+}
+
+// BeforeCreate hooks
+func (c *Challenge) BeforeCreate(tx *gorm.DB) error {
+	if c.Status == "" {
+		c.Status = "draft"
+	}
+	return nil
+}
+
+func (cp *ChallengeParticipant) BeforeCreate(tx *gorm.DB) error {
+	if cp.Status == "" {
+		cp.Status = "joined"
+	}
+	return nil
+}
+
+func (ct *ChallengeTeam) BeforeCreate(tx *gorm.DB) error {
+	if ct.Status == "" {
+		ct.Status = "active"
+	}
+	return nil
+}
+
+func (m *Mentorship) BeforeCreate(tx *gorm.DB) error {
+	if m.Status == "" {
+		m.Status = "pending"
+	}
+	if m.Currency == "" {
+		m.Currency = "USD"
+	}
+	return nil
+}
+
+func (ms *MentorshipSession) BeforeCreate(tx *gorm.DB) error {
+	if ms.Status == "" {
+		ms.Status = "scheduled"
+	}
+	return nil
+}
+
+func (mr *MentorshipReview) BeforeCreate(tx *gorm.DB) error {
+	if mr.ReviewType == "" {
+		mr.ReviewType = "mentor_review"
+	}
+	return nil
+}
+
+func (mm *MentorshipMilestone) BeforeCreate(tx *gorm.DB) error {
+	if mm.Status == "" {
+		mm.Status = "pending"
+	}
+	if mm.Priority == "" {
+		mm.Priority = "medium"
+	}
+	return nil
+}
+
+func (mr *MentorshipRequest) BeforeCreate(tx *gorm.DB) error {
+	if mr.Status == "" {
+		mr.Status = "pending"
+	}
+	if mr.Currency == "" {
+		mr.Currency = "USD"
+	}
+	return nil
+}

backend/models/course.go

@@ -0,0 +1,69 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// Course represents a Zero to Mastery course
+type Course struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Basic course information
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description" gorm:"type:text"`
+	Slug        string `json:"slug" gorm:"uniqueIndex;not null"` // URL-friendly course identifier
+	URL         string `json:"url" gorm:"not null"`              // ZTM course URL
+	Thumbnail   string `json:"thumbnail"`
+	Instructor  string `json:"instructor"`
+
+	// Course metadata
+	Duration      string  `json:"duration"`       // e.g., "32 Hours"
+	LessonsCount  int     `json:"lessons_count"`  // number of lessons
+	ModuleCount   int     `json:"module_count"`   // number of modules
+	Level         string  `json:"level"`          // beginner, intermediate, advanced
+	Category      string  `json:"category"`       // programming, design, cybersecurity, etc.
+	Price         float64 `json:"price"`          // course price
+	Rating        float64 `json:"rating"`         // average rating
+	StudentsCount int     `json:"students_count"` // number of enrolled students
+
+	// Course content
+	Prerequisites []string `json:"prerequisites" gorm:"serializer:json"`
+	WhatYouLearn  []string `json:"what_you_learn" gorm:"serializer:json"`
+	Topics        []string `json:"topics" gorm:"serializer:json"`
+	ToolsAndTech  []string `json:"tools_and_tech" gorm:"serializer:json"`
+
+	// ZTM specific data
+	ZTMCourseID    string     `json:"ztm_course_id"` // internal ZTM course ID
+	ZTMCategory    string     `json:"ztm_category"`  // ZTM category classification
+	IsZTMCourse    bool       `json:"is_ztm_course" gorm:"default:true"`
+	LastUpdatedZTM *time.Time `json:"last_updated_ztm"` // last sync with ZTM
+
+	// Status
+	IsActive   bool `json:"is_active" gorm:"default:true"`
+	IsFeatured bool `json:"is_featured" gorm:"default:false"`
+}
+
+// LearningPathCourse represents the relationship between learning paths and courses
+type LearningPathCourse struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	LearningPathID uint         `json:"learning_path_id" gorm:"not null;index"`
+	LearningPath   LearningPath `json:"learning_path,omitempty" gorm:"foreignKey:LearningPathID"`
+
+	CourseID uint   `json:"course_id" gorm:"not null;index"`
+	Course   Course `json:"course,omitempty" gorm:"foreignKey:CourseID"`
+
+	// Relationship metadata
+	Order          int    `json:"order" gorm:"not null"`           // order in the learning path
+	IsRequired     bool   `json:"is_required" gorm:"default:true"` // whether this course is required
+	Notes          string `json:"notes" gorm:"type:text"`          // additional notes about why this course is included
+	EstimatedWeeks int    `json:"estimated_weeks"`                 // estimated weeks to complete this course
+}

backend/models/file.go

@@ -28,24 +28,28 @@ type File struct {
 	UserID uint `json:"user_id" gorm:"not null;index"`
 	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
 
-	OriginalName string    `json:"original_name" gorm:"not null"`
-	FileName     string    `json:"file_name" gorm:"not null;uniqueIndex"`
-	FilePath     string    `json:"file_path" gorm:"not null"`
-	FileSize     int64     `json:"file_size" gorm:"not null"`
-	MimeType     string    `json:"mime_type" gorm:"not null"`
-	FileType     FileType  `json:"file_type" gorm:"not null"`
-	
+	OriginalName string   `json:"original_name" gorm:"not null"`
+	FileName     string   `json:"file_name" gorm:"not null;uniqueIndex"`
+	FilePath     string   `json:"file_path" gorm:"not null"`
+	FileSize     int64    `json:"file_size" gorm:"not null"`
+	MimeType     string   `json:"mime_type" gorm:"not null"`
+	FileType     FileType `json:"file_type" gorm:"not null"`
+
+	// Encryption
+	IsEncrypted   bool   `json:"is_encrypted" gorm:"default:false"`
+	EncryptionKey string `json:"-" gorm:"column:encryption_key"` // User-specific encryption key (optional)
+
 	// Organization
 	Tags []Tag `json:"tags,omitempty" gorm:"many2many:file_tags;"`
-	
+
 	// Metadata
 	Description string `json:"description"`
-	IsPublic     bool   `json:"is_public" gorm:"default:false"`
-	
+	IsPublic    bool   `json:"is_public" gorm:"default:false"`
+
 	// Preview/Thumbnail
 	ThumbnailPath string `json:"thumbnail_path"`
 	PreviewPath   string `json:"preview_path"`
-	
+
 	// Content extraction (for documents)
 	Content string `json:"content"`
 }

backend/models/file_analysis.go

@@ -0,0 +1,52 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// FileAnalysis represents analysis results for a file
+type FileAnalysis struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// File information
+	FileID       uint `json:"file_id" gorm:"not null;uniqueIndex:idx_file_analysis_type"`
+	File         File `json:"file,omitempty" gorm:"foreignKey:FileID"`
+	AnalysisType string `json:"analysis_type" gorm:"not null;uniqueIndex:idx_file_analysis_type"` // computer_vision, nlp, metadata
+
+	// Analysis results
+	Results    string  `json:"results" gorm:"type:text"`    // JSON-encoded analysis results
+	Confidence float64 `json:"confidence" gorm:"default:0.0"` // 0.0 to 1.0
+	Status     string  `json:"status" gorm:"default:pending"`  // pending, processing, completed, failed
+
+	// Processing metadata
+	ProcessedAt   *time.Time `json:"processed_at"`
+	ProcessingTime int        `json:"processing_time"` // in milliseconds
+	ModelVersion   string     `json:"model_version"`   // AI model version used
+	Error          string     `json:"error"`           // Error message if failed
+
+	// Additional metadata
+	Tags       string `json:"tags" gorm:"serializer:json"`
+	Metadata   string `json:"metadata" gorm:"serializer:json"`
+	ExtractedData string `json:"extracted_data" gorm:"type:text"` // Extracted text, objects, etc.
+}
+
+// TableName returns the table name for FileAnalysis
+func (FileAnalysis) TableName() string {
+	return "file_analyses"
+}
+
+// BeforeCreate hook to set default values
+func (fa *FileAnalysis) BeforeCreate(tx *gorm.DB) error {
+	if fa.Status == "" {
+		fa.Status = "pending"
+	}
+	if fa.Confidence == 0 {
+		fa.Confidence = 0.0
+	}
+	return nil
+}

backend/models/goals_habits.go

@@ -0,0 +1,173 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// Habit represents a habit that can be tracked
+type Habit struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Basic habit information
+	Name        string `json:"name" gorm:"not null"`
+	Description string `json:"description" gorm:"type:text"`
+	Category    string `json:"category" gorm:"default:personal"` // health, productivity, learning, personal
+
+	// Habit tracking
+	TargetFrequency int     `json:"target_frequency"` // e.g., 7 times per week
+	FrequencyUnit   string  `json:"frequency_unit"`   // daily, weekly, monthly
+	TargetValue     float64 `json:"target_value"`     // e.g., 30 minutes, 8 glasses
+	Unit            string  `json:"unit"`             // minutes, glasses, pages, etc.
+
+	// Schedule
+	TimeOfDay  string   `json:"time_of_day"`                         // morning, afternoon, evening, night
+	DaysOfWeek []string `json:"days_of_week" gorm:"serializer:json"` // ["monday", "tuesday", etc.]
+
+	// Status and settings
+	IsActive       bool    `json:"is_active" gorm:"default:true"`
+	IsPublic       bool    `json:"is_public" gorm:"default:false"`
+	Streak         int     `json:"streak" gorm:"default:0"`
+	LongestStreak  int     `json:"longest_streak" gorm:"default:0"`
+	CompletionRate float64 `json:"completion_rate" gorm:"default:0"` // percentage
+
+	// Relationships
+	GoalID       *uint        `json:"goal_id,omitempty"`
+	Goal         *Goal        `json:"goal,omitempty" gorm:"foreignKey:GoalID"`
+	HabitEntries []HabitEntry `json:"habit_entries,omitempty" gorm:"foreignKey:HabitID"`
+	HabitTags    []HabitTag   `json:"habit_tags,omitempty" gorm:"foreignKey:HabitID"`
+}
+
+// HabitEntry represents a single completion of a habit
+type HabitEntry struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	HabitID uint  `json:"habit_id" gorm:"not null;index"`
+	Habit   Habit `json:"habit,omitempty" gorm:"foreignKey:HabitID"`
+
+	EntryDate   time.Time `json:"entry_date" gorm:"not null;index"`
+	Value       float64   `json:"value"`        // actual value completed
+	TargetValue float64   `json:"target_value"` // target value for this entry
+	Unit        string    `json:"unit"`
+	Notes       string    `json:"notes" gorm:"type:text"`
+	IsCompleted bool      `json:"is_completed" gorm:"default:false"`
+	Quality     int       `json:"quality" gorm:"default:3"` // 1-5 rating
+	TimeSpent   int       `json:"time_spent"`               // minutes spent
+	Location    string    `json:"location"`
+	Mood        string    `json:"mood"` // happy, neutral, stressed, etc.
+}
+
+// GoalTag represents tags for goals
+type GoalTag struct {
+	ID     uint `json:"id" gorm:"primaryKey"`
+	GoalID uint `json:"goal_id" gorm:"not null;index"`
+	TagID  uint `json:"tag_id" gorm:"not null;index"`
+	Goal   Goal `json:"goal,omitempty" gorm:"foreignKey:GoalID"`
+	Tag    Tag  `json:"tag,omitempty" gorm:"foreignKey:TagID"`
+}
+
+// HabitTag represents tags for habits
+type HabitTag struct {
+	ID      uint  `json:"id" gorm:"primaryKey"`
+	HabitID uint  `json:"habit_id" gorm:"not null;index"`
+	TagID   uint  `json:"tag_id" gorm:"not null;index"`
+	Habit   Habit `json:"habit,omitempty" gorm:"foreignKey:HabitID"`
+	Tag     Tag   `json:"tag,omitempty" gorm:"foreignKey:TagID"`
+}
+
+// GoalTemplate represents templates for creating goals
+type GoalTemplate struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	Name        string  `json:"name" gorm:"not null"`
+	Description string  `json:"description" gorm:"type:text"`
+	Category    string  `json:"category"`
+	Unit        string  `json:"unit"`
+	TargetValue float64 `json:"target_value"`
+	Duration    int     `json:"duration"` // suggested duration in days
+	IsPublic    bool    `json:"is_public" gorm:"default:false"`
+	UsageCount  int     `json:"usage_count" gorm:"default:0"`
+
+	// Template milestones
+	Milestones []GoalTemplateMilestone `json:"milestones,omitempty" gorm:"foreignKey:GoalTemplateID"`
+}
+
+// GoalTemplateMilestone represents milestones in goal templates
+type GoalTemplateMilestone struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	GoalTemplateID uint         `json:"goal_template_id" gorm:"not null;index"`
+	GoalTemplate   GoalTemplate `json:"goal_template,omitempty" gorm:"foreignKey:GoalTemplateID"`
+
+	Title       string  `json:"title" gorm:"not null"`
+	Description string  `json:"description" gorm:"type:text"`
+	TargetValue float64 `json:"target_value"`
+	Unit        string  `json:"unit"`
+	DayOffset   int     `json:"day_offset"` // days from start date
+	SortOrder   int     `json:"sort_order" gorm:"default:0"`
+}
+
+// BeforeCreate hooks
+func (h *Habit) BeforeCreate(tx *gorm.DB) error {
+	if h.Category == "" {
+		h.Category = "personal"
+	}
+	if h.FrequencyUnit == "" {
+		h.FrequencyUnit = "daily"
+	}
+	return nil
+}
+
+func (he *HabitEntry) BeforeCreate(tx *gorm.DB) error {
+	// Set completion based on value vs target
+	if he.Value >= he.TargetValue {
+		he.IsCompleted = true
+	}
+	return nil
+}
+
+// BeforeUpdate hooks
+func (h *Habit) BeforeUpdate(tx *gorm.DB) error {
+	// Update completion rate and streak
+	h.updateStreakAndRate()
+	return nil
+}
+
+// Helper methods
+
+// updateStreakAndRate calculates current streak and completion rate
+func (h *Habit) updateStreakAndRate() {
+	// This would typically involve querying habit entries
+	// For now, we'll keep the existing values
+	// In a real implementation, you'd calculate based on recent entries
+}
+
+// GetTodayEntry gets today's habit entry if it exists
+func (h *Habit) GetTodayEntry() *HabitEntry {
+	// This would typically query the database
+	// For now, return nil
+	return nil
+}
+
+// GetWeeklyStreak gets the current weekly streak
+func (h *Habit) GetWeeklyStreak() int {
+	// This would calculate based on habit entries
+	// For now, return the stored streak
+	return h.Streak
+}

backend/models/integration.go

@@ -0,0 +1,293 @@
+package models
+
+import (
+	"time"
+	"gorm.io/gorm"
+)
+
+// IntegrationType represents the type of integration
+type IntegrationType string
+
+const (
+	IntegrationSlack   IntegrationType = "slack"
+	IntegrationDiscord IntegrationType = "discord"
+	IntegrationNotion  IntegrationType = "notion"
+	IntegrationPocket   IntegrationType = "pocket"
+	IntegrationTodoist  IntegrationType = "todoist"
+	IntegrationGoogle  IntegrationType = "google"
+	IntegrationGitHub  IntegrationType = "github"
+	IntegrationTwitter IntegrationType = "twitter"
+	IntegrationReddit  IntegrationType = "reddit"
+	IntegrationObsidian IntegrationType = "obsidian"
+)
+
+// IntegrationStatus represents the status of an integration
+type IntegrationStatus string
+
+const (
+	StatusActive   IntegrationStatus = "active"
+	StatusInactive IntegrationStatus = "inactive"
+	StatusError    IntegrationStatus = "error"
+	StatusPending  IntegrationStatus = "pending"
+)
+
+// Integration represents a third-party service integration
+type Integration struct {
+	ID           string            `json:"id" gorm:"primaryKey;type:uuid;default:gen_random_uuid()"`
+	UserID       string            `json:"userId" gorm:"not null;index;type:uuid"`
+	Type         IntegrationType   `json:"type" gorm:"not null;index"`
+	Status       IntegrationStatus `json:"status" gorm:"not null;default:'pending'"`
+	Name         string            `json:"name" gorm:"not null"`
+	Description  string            `json:"description"`
+	
+	// Configuration stored as JSON
+	Config       IntegrationConfig `json:"config" gorm:"type:jsonb"`
+	
+	// Authentication tokens (encrypted)
+	AccessToken  string            `json:"-" gorm:"type:text"` // Encrypted
+	RefreshToken string            `json:"-" gorm:"type:text"` // Encrypted
+	
+	// Sync settings
+	SyncEnabled  bool              `json:"syncEnabled" gorm:"default:true"`
+	LastSyncAt   *time.Time        `json:"lastSyncAt"`
+	SyncInterval int               `json:"syncInterval"` // in minutes, 0 = manual
+	
+	// Webhook settings
+	WebhookURL   string            `json:"webhookUrl" gorm:"type:text"`
+	WebhookSecret string           `json:"-" gorm:"type:text"` // Encrypted
+	
+	// Statistics
+	SyncCount    int               `json:"syncCount" gorm:"default:0"`
+	ErrorCount   int               `json:"errorCount" gorm:"default:0"`
+	LastError    string            `json:"lastError" gorm:"type:text"`
+	
+	// Timestamps
+	CreatedAt    time.Time         `json:"createdAt"`
+	UpdatedAt    time.Time         `json:"updatedAt"`
+	DeletedAt    gorm.DeletedAt    `json:"-" gorm:"index"`
+	
+	// Relationships
+	User         User              `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	SyncLogs     []SyncLog         `json:"syncLogs,omitempty" gorm:"foreignKey:IntegrationID"`
+}
+
+// IntegrationConfig holds configuration specific to each integration type
+type IntegrationConfig struct {
+	// Slack configuration
+	SlackConfig *SlackConfig `json:"slackConfig,omitempty"`
+	
+	// Discord configuration
+	DiscordConfig *DiscordConfig `json:"discordConfig,omitempty"`
+	
+	// Notion configuration
+	NotionConfig *NotionConfig `json:"notionConfig,omitempty"`
+	
+	// Google configuration
+	GoogleConfig *GoogleConfig `json:"googleConfig,omitempty"`
+	
+	// Pocket configuration
+	PocketConfig *PocketConfig `json:"pocketConfig,omitempty"`
+	
+	// Todoist configuration
+	TodoistConfig *TodoistConfig `json:"todoistConfig,omitempty"`
+	
+	// GitHub configuration
+	GitHubConfig *GitHubConfig `json:"gitHubConfig,omitempty"`
+	
+	// Twitter configuration
+	TwitterConfig *TwitterConfig `json:"twitterConfig,omitempty"`
+	
+	// Reddit configuration
+	RedditConfig *RedditConfig `json:"redditConfig,omitempty"`
+	
+	// Obsidian configuration
+	ObsidianConfig *ObsidianConfig `json:"obsidianConfig,omitempty"`
+}
+
+// SlackConfig holds Slack-specific configuration
+type SlackConfig struct {
+	TeamID      string   `json:"teamId"`
+	TeamName    string   `json:"teamName"`
+	ChannelID   string   `json:"channelId"`
+	ChannelName string   `json:"channelName"`
+	BotUserID   string   `json:"botUserId"`
+	Scopes      []string `json:"scopes"`
+	
+	// Notification settings
+	NotifyTasks       bool `json:"notifyTasks"`
+	NotifyBookmarks   bool `json:"notifyBookmarks"`
+	NotifyNotes       bool `json:"notifyNotes"`
+	NotifyDeadlines   bool `json:"notifyDeadlines"`
+	NotifyTimeEntries bool `json:"notifyTimeEntries"`
+}
+
+// DiscordConfig holds Discord-specific configuration
+type DiscordConfig struct {
+	GuildID     string   `json:"guildId"`
+	GuildName   string   `json:"guildName"`
+	ChannelID   string   `json:"channelId"`
+	ChannelName string   `json:"channelName"`
+	BotUserID   string   `json:"botUserId"`
+	Scopes      []string `json:"scopes"`
+	
+	// Notification settings
+	NotifyTasks       bool `json:"notifyTasks"`
+	NotifyBookmarks   bool `json:"notifyBookmarks"`
+	NotifyNotes       bool `json:"notifyNotes"`
+	NotifyDeadlines   bool `json:"notifyDeadlines"`
+	NotifyTimeEntries bool `json:"notifyTimeEntries"`
+}
+
+// NotionConfig holds Notion-specific configuration
+type NotionConfig struct {
+	DatabaseID string `json:"databaseId"`
+	WorkspaceID string `json:"workspaceId"`
+	WorkspaceName string `json:"workspaceName"`
+	
+	// Sync settings
+	SyncBookmarks bool `json:"syncBookmarks"`
+	SyncTasks     bool `json:"syncTasks"`
+	SyncNotes     bool `json:"syncNotes"`
+	SyncFiles     bool `json:"syncFiles"`
+	
+	// Mapping settings
+	BookmarkDatabaseID string `json:"bookmarkDatabaseId"`
+	TaskDatabaseID     string `json:"taskDatabaseId"`
+	NoteDatabaseID     string `json:"noteDatabaseId"`
+	FileDatabaseID     string `json:"fileDatabaseId"`
+}
+
+// GoogleConfig holds Google-specific configuration
+type GoogleConfig struct {
+	// Google Drive
+	DriveEnabled    bool   `json:"driveEnabled"`
+	DriveFolderID   string `json:"driveFolderId"`
+	
+	// Google Calendar
+	CalendarEnabled bool     `json:"calendarEnabled"`
+	CalendarIDs     []string `json:"calendarIds"`
+	
+	// Google Docs
+	DocsEnabled     bool `json:"docsEnabled"`
+	
+	// Sync settings
+	SyncBookmarks   bool `json:"syncBookmarks"`
+	SyncTasks       bool `json:"syncTasks"`
+	SyncNotes       bool `json:"syncNotes"`
+	SyncFiles       bool `json:"syncFiles"`
+	SyncCalendar    bool `json:"syncCalendar"`
+}
+
+// PocketConfig holds Pocket-specific configuration
+type PocketConfig struct {
+	Username string `json:"username"`
+	
+	// Sync settings
+	SyncBookmarks bool `json:"syncBookmarks"`
+	SyncTags     bool `json:"syncTags"`
+	ImportAll    bool `json:"importAll"`
+}
+
+// TodoistConfig holds Todoist-specific configuration
+type TodoistConfig struct {
+	ProjectID   string `json:"projectId"`
+	ProjectName string `json:"projectName"`
+	
+	// Sync settings
+	SyncTasks     bool `json:"syncTasks"`
+	SyncProjects  bool `json:"syncProjects"`
+	SyncLabels    bool `json:"syncLabels"`
+	ImportAll     bool `json:"importAll"`
+}
+
+// GitHubConfig holds GitHub-specific configuration
+type GitHubConfig struct {
+	Username     string `json:"username"`
+	RepoSync     bool   `json:"repoSync"`
+	IssueSync    bool   `json:"issueSync"`
+	PRSync       bool   `json:"prSync"`
+	StarSync     bool   `json:"starSync"`
+	WatchSync    bool   `json:"watchSync"`
+}
+
+// TwitterConfig holds Twitter-specific configuration
+type TwitterConfig struct {
+	Username     string `json:"username"`
+	SyncTweets   bool   `json:"syncTweets"`
+	SyncLikes    bool   `json:"syncLikes"`
+	SyncBookmarks bool `json:"syncBookmarks"`
+}
+
+// RedditConfig holds Reddit-specific configuration
+type RedditConfig struct {
+	Username     string `json:"username"`
+	SyncPosts    bool   `json:"syncPosts"`
+	SyncComments bool   `json:"syncComments"`
+	SyncSaved    bool   `json:"syncSaved"`
+	SyncUpvoted  bool   `json:"syncUpvoted"`
+}
+
+// ObsidianConfig holds Obsidian-specific configuration
+type ObsidianConfig struct {
+	VaultPath    string `json:"vaultPath"`
+	VaultName    string `json:"vaultName"`
+	SyncNotes    bool   `json:"syncNotes"`
+	SyncBookmarks bool `json:"syncBookmarks"`
+	SyncTasks    bool   `json:"syncTasks"`
+	AutoSync     bool   `json:"autoSync"`
+}
+
+// SyncLog represents a sync operation log
+type SyncLog struct {
+	ID           string    `json:"id" gorm:"primaryKey;type:uuid;default:gen_random_uuid()"`
+	IntegrationID string    `json:"integrationId" gorm:"not null;index;type:uuid"`
+	Type         string    `json:"type"` // "full", "incremental", "manual", "webhook"
+	Status       string    `json:"status"` // "success", "error", "partial"
+	
+	// Sync statistics
+	ItemsProcessed int       `json:"itemsProcessed"`
+	ItemsCreated   int       `json:"itemsCreated"`
+	ItemsUpdated   int       `json:"itemsUpdated"`
+	ItemsDeleted   int       `json:"itemsDeleted"`
+	ItemsSkipped   int       `json:"itemsSkipped"`
+	
+	// Timing
+	StartedAt     time.Time `json:"startedAt"`
+	CompletedAt   *time.Time `json:"completedAt"`
+	Duration      int       `json:"duration"` // in seconds
+	
+	// Error details
+	ErrorMessage  string    `json:"errorMessage" gorm:"type:text"`
+	ErrorDetails  string    `json:"errorDetails" gorm:"type:text"`
+	
+	// Additional data
+	SyncData      string    `json:"syncData" gorm:"type:jsonb"`
+	
+	// Timestamps
+	CreatedAt     time.Time `json:"createdAt"`
+	
+	// Relationships
+	Integration   Integration `json:"integration,omitempty" gorm:"foreignKey:IntegrationID"`
+}
+
+// WebhookEvent represents an incoming webhook event
+type WebhookEvent struct {
+	ID           string    `json:"id" gorm:"primaryKey;type:uuid;default:gen_random_uuid()"`
+	IntegrationID string    `json:"integrationId" gorm:"not null;index;type:uuid"`
+	Type         string    `json:"type"` // "slack", "discord", etc.
+	EventType    string    `json:"eventType"` // "message", "reaction_added", etc.
+	
+	// Event data
+	Payload      string    `json:"payload" gorm:"type:jsonb"`
+	Processed    bool      `json:"processed" gorm:"default:false"`
+	
+	// Processing details
+	ProcessedAt  *time.Time `json:"processedAt"`
+	ErrorMessage string    `json:"errorMessage" gorm:"type:text"`
+	
+	// Timestamps
+	CreatedAt    time.Time `json:"createdAt"`
+	
+	// Relationships
+	Integration  Integration `json:"integration,omitempty" gorm:"foreignKey:IntegrationID"`
+}

backend/models/knowledge_base.go

@@ -0,0 +1,246 @@
+package models
+
+import (
+	"regexp"
+	"strings"
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// WikiPage represents a page in the knowledge base/wiki
+type WikiPage struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Basic page information
+	Title   string `json:"title" gorm:"not null"`
+	Slug    string `json:"slug" gorm:"not null;uniqueIndex"`
+	Content string `json:"content" gorm:"type:text"`
+	Summary string `json:"summary" gorm:"type:text"`
+	Status  string `json:"status" gorm:"default:draft"` // draft, published, archived
+
+	// Organization
+	CategoryID *uint      `json:"category_id,omitempty"`
+	Category   *Category  `json:"category,omitempty" gorm:"foreignKey:CategoryID"`
+	ParentID   *uint      `json:"parent_id,omitempty"`
+	Parent     *WikiPage  `json:"parent,omitempty" gorm:"foreignKey:ParentID"`
+	Children   []WikiPage `json:"children,omitempty" gorm:"foreignKey:ParentID"`
+
+	// Metadata
+	Tags         []Tag      `json:"tags,omitempty" gorm:"many2many:wiki_page_tags;"`
+	Keywords     []string   `json:"keywords" gorm:"serializer:json"`
+	ReadingTime  int        `json:"reading_time"` // estimated minutes
+	WordCount    int        `json:"word_count"`
+	ViewCount    int        `json:"view_count" gorm:"default:0"`
+	LastViewedAt *time.Time `json:"last_viewed_at,omitempty"`
+	IsPublic     bool       `json:"is_public" gorm:"default:false"`
+	IsTemplate   bool       `json:"is_template" gorm:"default:false"`
+	TemplateID   *uint      `json:"template_id,omitempty"`
+	Template     *WikiPage  `json:"template,omitempty" gorm:"foreignKey:TemplateID"`
+
+	// Collaboration
+	IsCollaborative bool   `json:"is_collaborative" gorm:"default:false"`
+	Collaborators   []User `json:"collaborators,omitempty" gorm:"many2many:wiki_collaborators;"`
+	LastEditedBy    *uint  `json:"last_edited_by,omitempty"`
+	LastEditedUser  *User  `json:"last_edited_user,omitempty" gorm:"foreignKey:LastEditedBy"`
+	EditCount       int    `json:"edit_count" gorm:"default:0"`
+
+	// Relationships
+	Versions    []WikiVersion    `json:"versions,omitempty" gorm:"foreignKey:WikiPageID"`
+	Backlinks   []WikiBacklink   `json:"backlinks,omitempty" gorm:"foreignKey:TargetPageID"`
+	Attachments []WikiAttachment `json:"attachments,omitempty" gorm:"foreignKey:WikiPageID"`
+	Bookmarks   []Bookmark       `json:"bookmarks,omitempty" gorm:"foreignKey:WikiPageID"`
+	Notes       []Note           `json:"notes,omitempty" gorm:"foreignKey:WikiPageID"`
+}
+
+// Category represents a category for organizing wiki pages
+type Category struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Name        string     `json:"name" gorm:"not null"`
+	Slug        string     `json:"slug" gorm:"not null;uniqueIndex"`
+	Description string     `json:"description"`
+	Color       string     `json:"color" gorm:"default:#6366f1"`
+	Icon        string     `json:"icon"`
+	ParentID    *uint      `json:"parent_id,omitempty"`
+	Parent      *Category  `json:"parent,omitempty" gorm:"foreignKey:ParentID"`
+	Children    []Category `json:"children,omitempty" gorm:"foreignKey:ParentID"`
+	IsPublic    bool       `json:"is_public" gorm:"default:false"`
+	SortOrder   int        `json:"sort_order" gorm:"default:0"`
+
+	// Relationships
+	Pages []WikiPage `json:"pages,omitempty" gorm:"foreignKey:CategoryID"`
+}
+
+// WikiVersion represents a version history of a wiki page
+type WikiVersion struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	WikiPageID uint     `json:"wiki_page_id" gorm:"not null;index"`
+	WikiPage   WikiPage `json:"wiki_page,omitempty" gorm:"foreignKey:WikiPageID"`
+
+	VersionNumber int    `json:"version_number" gorm:"not null"`
+	Title         string `json:"title" gorm:"not null"`
+	Content       string `json:"content" gorm:"type:text"`
+	Summary       string `json:"summary" gorm:"type:text"`
+	ChangeLog     string `json:"change_log" gorm:"type:text"`
+
+	// Author information
+	AuthorID uint `json:"author_id" gorm:"not null"`
+	Author   User `json:"author,omitempty" gorm:"foreignKey:AuthorID"`
+
+	// Version metadata
+	WordCount         int  `json:"word_count"`
+	CharactersAdded   int  `json:"characters_added"`
+	CharactersRemoved int  `json:"characters_removed"`
+	IsMinorChange     bool `json:"is_minor_change" gorm:"default:false"`
+}
+
+// WikiBacklink represents a link between wiki pages
+type WikiBacklink struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	SourcePageID uint     `json:"source_page_id" gorm:"not null;index"`
+	SourcePage   WikiPage `json:"source_page,omitempty" gorm:"foreignKey:SourcePageID"`
+	TargetPageID uint     `json:"target_page_id" gorm:"not null;index"`
+	TargetPage   WikiPage `json:"target_page,omitempty" gorm:"foreignKey:TargetPageID"`
+
+	LinkText string `json:"link_text"`
+	Context  string `json:"context" gorm:"type:text"` // Surrounding text where the link appears
+}
+
+// WikiAttachment represents files attached to wiki pages
+type WikiAttachment struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	WikiPageID uint     `json:"wiki_page_id" gorm:"not null;index"`
+	WikiPage   WikiPage `json:"wiki_page,omitempty" gorm:"foreignKey:WikiPageID"`
+
+	FileName     string `json:"file_name" gorm:"not null"`
+	OriginalName string `json:"original_name" gorm:"not null"`
+	FilePath     string `json:"file_path" gorm:"not null"`
+	FileSize     int64  `json:"file_size"`
+	MimeType     string `json:"mime_type"`
+	Width        int    `json:"width"`  // For images
+	Height       int    `json:"height"` // For images
+	Thumbnail    string `json:"thumbnail"`
+	Description  string `json:"description"`
+	IsPublic     bool   `json:"is_public" gorm:"default:false"`
+}
+
+// Template represents reusable page templates
+type Template struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Name        string `json:"name" gorm:"not null"`
+	Slug        string `json:"slug" gorm:"not null;uniqueIndex"`
+	Description string `json:"description"`
+	Content     string `json:"content" gorm:"type:text"`
+	Category    string `json:"category"` // meeting, project, documentation, etc.
+	IsPublic    bool   `json:"is_public" gorm:"default:false"`
+	UsageCount  int    `json:"usage_count" gorm:"default:0"`
+
+	// Template variables
+	Variables []TemplateVariable `json:"variables,omitempty" gorm:"foreignKey:TemplateID"`
+}
+
+// TemplateVariable represents variables in templates
+type TemplateVariable struct {
+	ID        uint      `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+
+	TemplateID uint     `json:"template_id" gorm:"not null;index"`
+	Template   Template `json:"template,omitempty" gorm:"foreignKey:TemplateID"`
+
+	Name         string `json:"name" gorm:"not null"`
+	Type         string `json:"type" gorm:"not null"` // text, number, date, select
+	DefaultValue string `json:"default_value"`
+	Required     bool   `json:"required" gorm:"default:false"`
+	Description  string `json:"description"`
+	Options      string `json:"options" gorm:"serializer:json"` // For select type
+}
+
+// BeforeCreate hooks
+func (w *WikiPage) BeforeCreate(tx *gorm.DB) error {
+	if w.Status == "" {
+		w.Status = "draft"
+	}
+	if w.Slug == "" && w.Title != "" {
+		w.Slug = generateSlug(w.Title)
+	}
+	return nil
+}
+
+func (c *Category) BeforeCreate(tx *gorm.DB) error {
+	if c.Slug == "" && c.Name != "" {
+		c.Slug = generateSlug(c.Name)
+	}
+	return nil
+}
+
+func (t *Template) BeforeCreate(tx *gorm.DB) error {
+	if t.Slug == "" && t.Name != "" {
+		t.Slug = generateSlug(t.Name)
+	}
+	return nil
+}
+
+// BeforeUpdate hooks
+func (w *WikiPage) BeforeUpdate(tx *gorm.DB) error {
+	if w.Title != "" {
+		w.Slug = generateSlug(w.Title)
+	}
+	if w.Content != "" {
+		w.WordCount = len(strings.Fields(w.Content))
+		w.ReadingTime = estimateReadingTime(w.WordCount)
+	}
+	return nil
+}
+
+// Helper functions
+func generateSlug(title string) string {
+	// Simple slug generation - in production, you'd want more sophisticated handling
+	slug := strings.ToLower(title)
+	slug = strings.ReplaceAll(slug, " ", "-")
+	slug = regexp.MustCompile(`[^a-z0-9-]`).ReplaceAllString(slug, "")
+	slug = regexp.MustCompile(`-+`).ReplaceAllString(slug, "-")
+	slug = strings.Trim(slug, "-")
+	return slug
+}
+
+func estimateReadingTime(wordCount int) int {
+	readingSpeed := 225 // words per minute
+	readingTime := wordCount / readingSpeed
+	if readingTime < 1 {
+		readingTime = 1
+	}
+	return readingTime
+}

backend/models/learning_path.go

@@ -0,0 +1,142 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// LearningPath represents a structured learning path
+type LearningPath struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Basic information
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description"`
+	Category    string `json:"category" gorm:"not null"`           // programming, design, business, etc.
+	Difficulty  string `json:"difficulty" gorm:"default:beginner"` // beginner, intermediate, advanced
+
+	// Metadata
+	Duration    string `json:"duration"`  // estimated time to complete
+	Thumbnail   string `json:"thumbnail"` // cover image
+	IsPublished bool   `json:"is_published" gorm:"default:false"`
+	IsFeatured  bool   `json:"is_featured" gorm:"default:false"`
+
+	// Creator information
+	CreatorID uint `json:"creator_id" gorm:"not null;index"`
+	Creator   User `json:"creator,omitempty" gorm:"foreignKey:CreatorID"`
+
+	// Relationships
+	Modules     []LearningModule     `json:"modules,omitempty" gorm:"foreignKey:LearningPathID"`
+	Courses     []LearningPathCourse `json:"courses,omitempty" gorm:"foreignKey:LearningPathID"`
+	Tags        []Tag                `json:"tags,omitempty" gorm:"many2many:learning_path_tags;"`
+	Enrollments []Enrollment         `json:"enrollments,omitempty" gorm:"foreignKey:LearningPathID"`
+
+	// Statistics
+	EnrollmentCount int     `json:"enrollment_count" gorm:"default:0"`
+	Rating          float64 `json:"rating" gorm:"default:0"`
+	ReviewCount     int     `json:"review_count" gorm:"default:0"`
+}
+
+// LearningModule represents a module within a learning path
+type LearningModule struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Basic information
+	LearningPathID uint         `json:"learning_path_id" gorm:"not null;index"`
+	LearningPath   LearningPath `json:"learning_path,omitempty" gorm:"foreignKey:LearningPathID"`
+
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description"`
+	Content     string `json:"content" gorm:"type:text"`
+	Order       int    `json:"order" gorm:"not null"`
+
+	// Module type
+	ModuleType string `json:"module_type" gorm:"default:lesson"` // lesson, project, quiz, video, reading
+
+	// Resources
+	Resources []ModuleResource `json:"resources,omitempty" gorm:"foreignKey:LearningModuleID"`
+
+	// Completion tracking
+	EstimatedDuration string `json:"estimated_duration"`
+	IsRequired        bool   `json:"is_required" gorm:"default:true"`
+}
+
+// ModuleResource represents a resource within a learning module
+type ModuleResource struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	LearningModuleID uint           `json:"learning_module_id" gorm:"not null;index"`
+	LearningModule   LearningModule `json:"learning_module,omitempty" gorm:"foreignKey:LearningModuleID"`
+
+	Title       string `json:"title" gorm:"not null"`
+	URL         string `json:"url"`
+	Type        string `json:"type" gorm:"not null"` // video, article, book, tool, download
+	Description string `json:"description"`
+	Order       int    `json:"order" gorm:"not null"`
+
+	// External resource metadata
+	Thumbnail  string `json:"thumbnail"`
+	Duration   string `json:"duration"`
+	IsExternal bool   `json:"is_external" gorm:"default:true"`
+}
+
+// Enrollment represents a user's enrollment in a learning path
+type Enrollment struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID         uint         `json:"user_id" gorm:"not null;index"`
+	User           User         `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	LearningPathID uint         `json:"learning_path_id" gorm:"not null;index"`
+	LearningPath   LearningPath `json:"learning_path,omitempty" gorm:"foreignKey:LearningPathID"`
+	CourseID       *uint        `json:"course_id,omitempty"` // for direct course enrollment
+	Course         *Course      `json:"course,omitempty" gorm:"foreignKey:CourseID"`
+
+	// Enrollment status
+	Status      string     `json:"status" gorm:"default:enrolled"` // enrolled, in_progress, completed, dropped
+	StartedAt   *time.Time `json:"started_at"`
+	CompletedAt *time.Time `json:"completed_at"`
+
+	// Progress tracking
+	Progress         float64 `json:"progress" gorm:"default:0"` // percentage 0-100
+	CompletedModules []uint  `json:"completed_modules" gorm:"serializer:json"`
+	CurrentModuleID  *uint   `json:"current_module_id"`
+
+	// User feedback
+	Rating     *float64   `json:"rating"`
+	Review     string     `json:"review"`
+	ReviewDate *time.Time `json:"review_date"`
+}
+
+// Progress represents a user's progress in a specific module
+type Progress struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID           uint `json:"user_id" gorm:"not null;index"`
+	EnrollmentID     uint `json:"enrollment_id" gorm:"not null;index"`
+	LearningModuleID uint `json:"learning_module_id" gorm:"not null;index"`
+
+	// Progress status
+	Status      string     `json:"status" gorm:"default:not_started"` // not_started, in_progress, completed
+	StartedAt   *time.Time `json:"started_at"`
+	CompletedAt *time.Time `json:"completed_at"`
+
+	// Progress details
+	TimeSpent    int    `json:"time_spent"`                     // minutes
+	ProgressData string `json:"progress_data" gorm:"type:json"` // additional progress data
+}

backend/models/marketplace.go

@@ -0,0 +1,230 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// MarketplaceItem represents an item in the knowledge marketplace
+type MarketplaceItem struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Creator information
+	SellerID uint `json:"seller_id" gorm:"not null;index"`
+	Seller   User `json:"seller,omitempty" gorm:"foreignKey:SellerID"`
+
+	// Basic information
+	Title       string `json:"title" gorm:"not null"`
+	Description string `json:"description" gorm:"type:text"`
+	Category    string `json:"category" gorm:"not null"` // course, template, tool, guide, resource
+
+	// Content type and reference
+	ContentType   string `json:"content_type" gorm:"not null"` // bookmark_collection, note_template, course, learning_path, tool
+	ContentID     *uint  `json:"content_id,omitempty"`         // Reference to actual content
+	ContentURL    string `json:"content_url"`                  // Download/access URL
+	PreviewURL    string `json:"preview_url"`                  // Preview/demo URL
+	Thumbnail     string `json:"thumbnail"`                    // Item thumbnail
+
+	// Pricing
+	Price         float64 `json:"price" gorm:"default:0"`         // Price in USD
+	Currency      string  `json:"currency" gorm:"default:USD"`  // Currency code
+	IsFree        bool    `json:"is_free" gorm:"default:false"`  // Free item
+	Subscription  bool    `json:"subscription" gorm:"default:false"` // Subscription-based
+	SubscriptionPrice float64 `json:"subscription_price" gorm:"default:0"` // Monthly subscription price
+
+	// Ratings and reviews
+	Rating       float64 `json:"rating" gorm:"default:0"`       // Average rating (1-5)
+	ReviewCount  int     `json:"review_count" gorm:"default:0"` // Number of reviews
+	DownloadCount int    `json:"download_count" gorm:"default:0"` // Number of downloads
+
+	// Status and visibility
+	Status       string `json:"status" gorm:"default:draft"` // draft, published, suspended, removed
+	IsFeatured   bool   `json:"is_featured" gorm:"default:false"` // Featured item
+	IsApproved   bool   `json:"is_approved" gorm:"default:false"` // Admin approved
+	ApprovedAt   *time.Time `json:"approved_at,omitempty"`
+	ApprovedBy   *uint  `json:"approved_by,omitempty"`
+	Approver     *User  `json:"approver,omitempty" gorm:"foreignKey:ApprovedBy"`
+
+	// Tags and metadata
+	Tags        []MarketplaceTag `json:"tags,omitempty" gorm:"many2many:marketplace_item_tags;"`
+	License     string           `json:"license" gorm:"default:standard"` // License type
+	Version     string           `json:"version" gorm:"default:1.0"`     // Version
+	LastUpdated *time.Time       `json:"last_updated,omitempty"`
+
+	// Analytics
+	ViewCount    int       `json:"view_count" gorm:"default:0"`
+	LastViewedAt *time.Time `json:"last_viewed_at,omitempty"`
+
+	// Relationships
+	Reviews     []MarketplaceReview     `json:"reviews,omitempty" gorm:"foreignKey:ItemID"`
+	Purchases   []MarketplacePurchase   `json:"purchases,omitempty" gorm:"foreignKey:ItemID"`
+}
+
+// MarketplaceTag represents tags for marketplace items
+type MarketplaceTag struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	Name        string `json:"name" gorm:"uniqueIndex;not null"`
+	Description string `json:"description"`
+	Color       string `json:"color" gorm:"default:#6366f1"` // Tag color
+	UsageCount  int    `json:"usage_count" gorm:"default:0"`
+}
+
+// MarketplaceReview represents a review for a marketplace item
+type MarketplaceReview struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Review information
+	ItemID     uint  `json:"item_id" gorm:"not null;index"`
+	Item       MarketplaceItem `json:"item,omitempty" gorm:"foreignKey:ItemID"`
+	ReviewerID uint  `json:"reviewer_id" gorm:"not null;index"`
+	Reviewer   User  `json:"reviewer,omitempty" gorm:"foreignKey:ReviewerID"`
+
+	// Review content
+	Rating  int    `json:"rating" gorm:"not null;check:rating >= 1 AND rating <= 5"` // 1-5 stars
+	Title   string `json:"title"`
+	Content string `json:"content" gorm:"type:text"`
+
+	// Review metadata
+	HelpfulCount int       `json:"helpful_count" gorm:"default:0"`
+	IsVerified   bool      `json:"is_verified" gorm:"default:false"` // Verified purchase
+	PurchaseID   *uint     `json:"purchase_id,omitempty"`
+	ReviewedAt   time.Time `json:"reviewed_at"`
+
+	// Status
+	Status string `json:"status" gorm:"default:published"` // published, hidden, removed
+}
+
+// MarketplacePurchase represents a purchase from the marketplace
+type MarketplacePurchase struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Purchase information
+	ItemID    uint `json:"item_id" gorm:"not null;index"`
+	Item      MarketplaceItem `json:"item,omitempty" gorm:"foreignKey:ItemID"`
+	BuyerID   uint `json:"buyer_id" gorm:"not null;index"`
+	Buyer     User `json:"buyer,omitempty" gorm:"foreignKey:BuyerID"`
+
+	// Purchase details
+	Price        float64 `json:"price" gorm:"not null"`
+	Currency     string  `json:"currency" gorm:"default:USD"`
+	PaymentMethod string `json:"payment_method"` // stripe, paypal, crypto
+	TransactionID string `json:"transaction_id" gorm:"uniqueIndex"`
+
+	// License and access
+	LicenseType  string    `json:"license_type" gorm:"default:personal"` // personal, commercial, enterprise
+	AccessGranted bool     `json:"access_granted" gorm:"default:true"`
+	ExpiresAt    *time.Time `json:"expires_at,omitempty"` // For subscriptions
+
+	// Status
+	Status string `json:"status" gorm:"default:completed"` // pending, completed, refunded, cancelled
+	RefundedAt *time.Time `json:"refunded_at,omitempty"`
+	RefundReason string `json:"refund_reason,omitempty"`
+
+	// Analytics
+	DownloadCount int       `json:"download_count" gorm:"default:0"`
+	LastDownloadAt *time.Time `json:"last_download_at,omitempty"`
+}
+
+// ContentShare represents shared content links
+type ContentShare struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Owner information
+	OwnerID uint `json:"owner_id" gorm:"not null;index"`
+	Owner   User `json:"owner,omitempty" gorm:"foreignKey:OwnerID"`
+
+	// Content information
+	ContentType string `json:"content_type" gorm:"not null"` // bookmark, note, file, task, goal
+	ContentID   uint   `json:"content_id" gorm:"not null"`
+
+	// Share settings
+	ShareToken   string `json:"share_token" gorm:"uniqueIndex;not null"`
+	ShareURL     string `json:"share_url"`
+	Title        string `json:"title"`
+	Description  string `json:"description"`
+	Password     string `json:"-" gorm:"column:password"` // Optional password protection
+	ExpiresAt    *time.Time `json:"expires_at,omitempty"`
+
+	// Access control
+	AllowDownload bool `json:"allow_download" gorm:"default:true"`
+	AllowComment  bool `json:"allow_comment" gorm:"default:false"`
+	AllowEdit     bool `json:"allow_edit" gorm:"default:false"`
+
+	// Analytics
+	ViewCount    int       `json:"view_count" gorm:"default:0"`
+	DownloadCount int      `json:"download_count" gorm:"default:0"`
+	LastAccessedAt *time.Time `json:"last_accessed_at,omitempty"`
+
+	// Status
+	IsActive bool `json:"is_active" gorm:"default:true"`
+}
+
+// BeforeCreate hooks
+func (m *MarketplaceItem) BeforeCreate(tx *gorm.DB) error {
+	if m.Status == "" {
+		m.Status = "draft"
+	}
+	if m.Currency == "" {
+		m.Currency = "USD"
+	}
+	if m.Version == "" {
+		m.Version = "1.0"
+	}
+	if m.License == "" {
+		m.License = "standard"
+	}
+	return nil
+}
+
+func (r *MarketplaceReview) BeforeCreate(tx *gorm.DB) error {
+	if r.Status == "" {
+		r.Status = "published"
+	}
+	r.ReviewedAt = time.Now()
+	return nil
+}
+
+func (p *MarketplacePurchase) BeforeCreate(tx *gorm.DB) error {
+	if p.Status == "" {
+		p.Status = "completed"
+	}
+	if p.Currency == "" {
+		p.Currency = "USD"
+	}
+	if p.LicenseType == "" {
+		p.LicenseType = "personal"
+	}
+	return nil
+}
+
+func (s *ContentShare) BeforeCreate(tx *gorm.DB) error {
+	if s.ShareToken == "" {
+		// Generate a unique share token
+		s.ShareToken = generateShareToken()
+	}
+	return nil
+}
+
+// Helper function to generate share tokens
+func generateShareToken() string {
+	// This should generate a cryptographically secure random token
+	// For now, using a simple implementation
+	return "share_" + time.Now().Format("20060102150405")
+}

backend/models/models.go

@@ -25,5 +25,93 @@ func AutoMigrate() {
 		&Task{},
 		&File{},
 		&Note{},
+		&TimeEntry{},
+		&FileAnalysis{},
+		&ChatSession{},
+		&ChatMessage{},
+		&LearningPath{},
+		&LearningModule{},
+		&ModuleResource{},
+		&Enrollment{},
+		&Progress{},
+		&Course{},
+		&LearningPathCourse{},
+		&CalendarEvent{},
+		&RecurrenceRule{},
+		&CalendarSettings{},
+		// Search models
+		&ContentEmbedding{},
+		&SavedSearch{},
+		&SavedSearchTag{},
+		&SearchAnalytics{},
+		&SearchSuggestion{},
+		// AI Feature models
+		&AISummary{},
+		&AITaskSuggestion{},
+		&UserAISettings{},
+		&AITagSuggestion{},
+		&AIContentGeneration{},
+		&AICodeReview{},
+		&AILearningRecommendation{},
+		// Advanced AI Recommendation models
+		&AIRecommendation{},
+		&UserPreference{},
+		&RecommendationInteraction{},
+		// Integration models
+		&Integration{},
+		&SyncLog{},
+		&WebhookEvent{},
+		// Analytics models
+		&Analytics{},
+		&ProductivityMetrics{},
+		&LearningAnalytics{},
+		&ContentAnalytics{},
+		&GitHubAnalytics{},
+		&HabitAnalytics{},
+		&Goal{},
+		&Milestone{},
+		&AnalyticsReport{},
+		// Social features models
+		&Skill{},
+		&Project{},
+		&ProjectTag{},
+		&SocialLink{},
+		&Follow{},
+		// Team workspace models
+		&Team{},
+		&TeamMember{},
+		&TeamInvitation{},
+		&TeamProject{},
+		&TeamProjectTag{},
+		&TeamBookmark{},
+		&TeamNote{},
+		&TeamTask{},
+		&TeamFile{},
+		&TeamActivity{},
+		// Security models
+		&AuditLog{},
+		// Marketplace models
+		&MarketplaceItem{},
+		&MarketplaceTag{},
+		&MarketplaceReview{},
+		&MarketplacePurchase{},
+		&ContentShare{},
+		// Community models
+		&Challenge{},
+		&ChallengeParticipant{},
+		&ChallengeTeam{},
+		&ChallengeMilestone{},
+		&ChallengeMilestoneCompletion{},
+		&ChallengeResource{},
+		&ChallengeTag{},
+		&Mentorship{},
+		&MentorshipSession{},
+		&MentorshipReview{},
+		&MentorshipMilestone{},
+		&MentorshipRequest{},
+		// YouTube cache models
+		&YouTubeChannelCache{},
+		// Video bookmark models
+		&VideoBookmark{},
 	)
 }

backend/models/note.go

@@ -16,22 +16,26 @@ type Note struct {
 	UserID uint `json:"user_id" gorm:"not null;index"`
 	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
 
-	Title string `json:"title" gorm:"not null"`
+	Title   string `json:"title" gorm:"not null"`
 	Content string `json:"content" gorm:"type:text"`
-	
+
+	// Encryption
+	IsEncrypted   bool   `json:"is_encrypted" gorm:"default:false"`
+	EncryptionKey string `json:"-" gorm:"column:encryption_key"` // User-specific encryption key (optional)
+
 	// Organization
 	Tags []Tag `json:"tags,omitempty" gorm:"many2many:note_tags;"`
-	
+
 	// Metadata
 	Description string `json:"description"`
 	IsPublic    bool   `json:"is_public" gorm:"default:false"`
 	IsPinned    bool   `json:"is_pinned" gorm:"default:false"`
-	
+
 	// Formatting
 	ContentType string `json:"content_type" gorm:"default:markdown"` // markdown, html, plain
-	
+
 	// Relationships
-	ParentNoteID *uint `json:"parent_note_id,omitempty"`
-	ParentNote   *Note `json:"parent_note,omitempty" gorm:"foreignKey:ParentNoteID"`
+	ParentNoteID *uint  `json:"parent_note_id,omitempty"`
+	ParentNote   *Note  `json:"parent_note,omitempty" gorm:"foreignKey:ParentNoteID"`
 	Subnotes     []Note `json:"subnotes,omitempty" gorm:"foreignKey:ParentNoteID"`
 }

backend/models/search.go

@@ -0,0 +1,111 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// ContentEmbedding stores vector embeddings for semantic search
+type ContentEmbedding struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// Content reference
+	ContentType string `json:"content_type" gorm:"not null;index"` // 'bookmark', 'task', 'note', 'file'
+	ContentID   uint   `json:"content_id" gorm:"not null;index"`
+
+	// Embedding data
+	Embedding   string  `json:"embedding" gorm:"type:text"` // JSON array of floats
+	Model       string  `json:"model" gorm:"not null"`       // AI model used
+	Dimensions  int     `json:"dimensions" gorm:"not null"`  // Vector dimensions
+	TextContent string  `json:"text_content" gorm:"type:text"` // Original text for embedding
+
+	// Metadata
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+}
+
+// SavedSearch represents a user's saved search query
+type SavedSearch struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Name        string          `json:"name" gorm:"not null"`
+	Query       string          `json:"query" gorm:"not null"`
+	Filters     string          `json:"filters" gorm:"type:json"` // JSON serialized filters
+	Alert       bool            `json:"alert" gorm:"default:false"`
+	LastRun     *time.Time      `json:"last_run"`
+	RunCount    int             `json:"run_count" gorm:"default:0"`
+	IsPublic    bool            `json:"is_public" gorm:"default:false"`
+	Description string          `json:"description"`
+	Tags        []SavedSearchTag `json:"tags,omitempty" gorm:"many2many:saved_search_tags;"`
+}
+
+// SavedSearchTag represents tags for saved searches
+type SavedSearchTag struct {
+	ID        uint      `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+
+	Name  string `json:"name" gorm:"unique;not null"`
+	Color string `json:"color" gorm:"default:#3b82f6"`
+}
+
+// SearchAnalytics stores search analytics data
+type SearchAnalytics struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	Query       string    `json:"query" gorm:"not null;index"`
+	Filters     string    `json:"filters" gorm:"type:json"`
+	ResultsCount int      `json:"results_count"`
+	Took        int       `json:"took"` // Time in milliseconds
+	ContentType string    `json:"content_type"`
+	ClickedResultID *uint  `json:"clicked_result_id"` // Track which result was clicked
+	SessionID   string    `json:"session_id" gorm:"index"`
+	IPAddress   string    `json:"ip_address"`
+	UserAgent   string    `json:"user_agent"`
+}
+
+// SearchSuggestion represents search suggestions
+type SearchSuggestion struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	Text        string  `json:"text" gorm:"not null;uniqueIndex"`
+	Type        string  `json:"type" gorm:"not null"` // 'query', 'tag', 'content'
+	Frequency   int     `json:"frequency" gorm:"default:1"`
+	LastUsed    time.Time `json:"last_used"`
+	ContentType *string `json:"content_type,omitempty"`
+	IsPublic    bool    `json:"is_public" gorm:"default:true"`
+}
+
+// BeforeCreate hook for ContentEmbedding
+func (ce *ContentEmbedding) BeforeCreate(tx *gorm.DB) error {
+	// Set default model if not specified
+	if ce.Model == "" {
+		ce.Model = "text-embedding-ada-002"
+	}
+	
+	// Set default dimensions if not specified
+	if ce.Dimensions == 0 {
+		ce.Dimensions = 1536 // Default for OpenAI embeddings
+	}
+	
+	return nil
+}

backend/models/social.go

@@ -0,0 +1,96 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// Skill represents a user's skill
+type Skill struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint   `json:"user_id" gorm:"not null;index"`
+	Name   string `json:"name" gorm:"not null"`
+	Level  string `json:"level" gorm:"default:intermediate"` // beginner, intermediate, advanced, expert
+	Category string `json:"category"` // programming, design, business, etc.
+	Endorsements int `json:"endorsements" gorm:"default:0"`
+	Verified bool `json:"verified" gorm:"default:false"`
+
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+}
+
+// Project represents a user's project showcase
+type Project struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID          uint   `json:"user_id" gorm:"not null;index"`
+	Title           string `json:"title" gorm:"not null"`
+	Description     string `json:"description"`
+	RepositoryURL   string `json:"repository_url"`
+	LiveURL         string `json:"live_url"`
+	Thumbnail       string `json:"thumbnail"`
+	Tags            []ProjectTag `json:"tags,omitempty" gorm:"foreignKey:ProjectID"`
+	Featured        bool   `json:"featured" gorm:"default:false"`
+	Views           int    `json:"views" gorm:"default:0"`
+	Likes           int    `json:"likes" gorm:"default:0"`
+
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+}
+
+// ProjectTag represents tags for projects
+type ProjectTag struct {
+	ID        uint   `json:"id" gorm:"primaryKey"`
+	ProjectID uint   `json:"project_id" gorm:"not null;index"`
+	Tag       string `json:"tag" gorm:"not null"`
+}
+
+// SocialLink represents social media links
+type SocialLink struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint   `json:"user_id" gorm:"not null;index"`
+	Platform string `json:"platform" gorm:"not null"` // github, linkedin, twitter, etc.
+	URL     string `json:"url" gorm:"not null"`
+	Username string `json:"username"`
+	Verified bool `json:"verified" gorm:"default:false"`
+
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+}
+
+// Follow represents user following relationships
+type Follow struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	FollowerID uint `json:"follower_id" gorm:"not null;index"`
+	FollowingID uint `json:"following_id" gorm:"not null;index"`
+
+	Follower  User `json:"follower,omitempty" gorm:"foreignKey:FollowerID"`
+	Following User `json:"following,omitempty" gorm:"foreignKey:FollowingID"`
+}
+
+// UserProfileStats represents aggregated user statistics
+type UserProfileStats struct {
+	UserID            uint    `json:"user_id"`
+	FollowersCount    int     `json:"followers_count"`
+	FollowingCount    int     `json:"following_count"`
+	PublicBookmarks   int     `json:"public_bookmarks"`
+	PublicNotes       int     `json:"public_notes"`
+	ProjectsCount     int     `json:"projects_count"`
+	SkillsCount       int     `json:"skills_count"`
+	TotalViews        int     `json:"total_views"`
+	TotalLikes        int     `json:"total_likes"`
+	ProfileCompletion float64 `json:"profile_completion"` // 0-100 percentage
+}

backend/models/teams.go

@@ -0,0 +1,190 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// Team represents a collaborative workspace
+type Team struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	Name        string `json:"name" gorm:"not null"`
+	Description string `json:"description"`
+	Avatar      string `json:"avatar"`
+	IsPublic    bool   `json:"is_public" gorm:"default:false"`
+	IsActive    bool   `json:"is_active" gorm:"default:true"`
+
+	// Owner of the team
+	OwnerID uint `json:"owner_id" gorm:"not null;index"`
+	Owner   User `json:"owner,omitempty" gorm:"foreignKey:OwnerID"`
+
+	// Team members and relationships
+	Members     []TeamMember     `json:"members,omitempty" gorm:"foreignKey:TeamID"`
+	Invitations []TeamInvitation `json:"invitations,omitempty" gorm:"foreignKey:TeamID"`
+	Projects    []TeamProject    `json:"projects,omitempty" gorm:"foreignKey:TeamID"`
+	Bookmarks   []TeamBookmark   `json:"bookmarks,omitempty" gorm:"foreignKey:TeamID"`
+	Notes       []TeamNote       `json:"notes,omitempty" gorm:"foreignKey:TeamID"`
+	Tasks       []TeamTask       `json:"tasks,omitempty" gorm:"foreignKey:TeamID"`
+	Files       []TeamFile       `json:"files,omitempty" gorm:"foreignKey:TeamID"`
+}
+
+// TeamMember represents a user's membership in a team
+type TeamMember struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID   uint      `json:"team_id" gorm:"not null;index"`
+	UserID   uint      `json:"user_id" gorm:"not null;index"`
+	Role     string    `json:"role" gorm:"default:member"` // owner, admin, member, viewer
+	JoinedAt time.Time `json:"joined_at"`
+
+	Team Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+}
+
+// TeamInvitation represents an invitation to join a team
+type TeamInvitation struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID    uint      `json:"team_id" gorm:"not null;index"`
+	UserID    uint      `json:"user_id" gorm:"not null;index"`
+	Email     string    `json:"email" gorm:"not null"` // Email for non-registered users
+	Role      string    `json:"role" gorm:"default:member"`
+	Token     string    `json:"token" gorm:"uniqueIndex;not null"` // Invitation token
+	Status    string    `json:"status" gorm:"default:pending"`     // pending, accepted, declined, expired
+	ExpiresAt time.Time `json:"expires_at"`
+	InvitedBy uint      `json:"invited_by" gorm:"not null"`
+
+	Team    Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User    User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	Inviter User `json:"inviter,omitempty" gorm:"foreignKey:InvitedBy"`
+}
+
+// TeamProject represents a project within a team
+type TeamProject struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID        uint             `json:"team_id" gorm:"not null;index"`
+	Name          string           `json:"name" gorm:"not null"`
+	Description   string           `json:"description"`
+	Status        string           `json:"status" gorm:"default:active"` // active, archived, completed
+	RepositoryURL string           `json:"repository_url"`
+	LiveURL       string           `json:"live_url"`
+	Tags          []TeamProjectTag `json:"tags,omitempty" gorm:"foreignKey:ProjectID"`
+
+	Team Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+}
+
+// TeamProjectTag represents tags for team projects
+type TeamProjectTag struct {
+	ID        uint   `json:"id" gorm:"primaryKey"`
+	ProjectID uint   `json:"project_id" gorm:"not null;index"`
+	Tag       string `json:"tag" gorm:"not null"`
+}
+
+// TeamBookmark represents a bookmark shared within a team
+type TeamBookmark struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID     uint `json:"team_id" gorm:"not null;index"`
+	UserID     uint `json:"user_id" gorm:"not null;index"`
+	BookmarkID uint `json:"bookmark_id" gorm:"not null;index"`
+
+	Team     Team     `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User     User     `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	Bookmark Bookmark `json:"bookmark,omitempty" gorm:"foreignKey:BookmarkID"`
+}
+
+// TeamNote represents a note shared within a team
+type TeamNote struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID uint `json:"team_id" gorm:"not null;index"`
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	NoteID uint `json:"note_id" gorm:"not null;index"`
+
+	Team Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	Note Note `json:"note,omitempty" gorm:"foreignKey:NoteID"`
+}
+
+// TeamTask represents a task within a team
+type TeamTask struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID uint `json:"team_id" gorm:"not null;index"`
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	TaskID uint `json:"task_id" gorm:"not null;index"`
+
+	Team Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	Task Task `json:"task,omitempty" gorm:"foreignKey:TaskID"`
+}
+
+// TeamFile represents a file shared within a team
+type TeamFile struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID uint `json:"team_id" gorm:"not null;index"`
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	FileID uint `json:"file_id" gorm:"not null;index"`
+
+	Team Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+	File File `json:"file,omitempty" gorm:"foreignKey:FileID"`
+}
+
+// TeamActivity represents activity logs for team actions
+type TeamActivity struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	TeamID     uint   `json:"team_id" gorm:"not null;index"`
+	UserID     uint   `json:"user_id" gorm:"not null;index"`
+	Action     string `json:"action" gorm:"not null"`      // created, updated, deleted, joined, left, etc.
+	EntityType string `json:"entity_type" gorm:"not null"` // team, project, bookmark, note, task, file
+	EntityID   uint   `json:"entity_id" gorm:"not null"`
+	Details    string `json:"details"` // JSON string with additional details
+
+	Team Team `json:"team,omitempty" gorm:"foreignKey:TeamID"`
+	User User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+}
+
+// TeamStats represents aggregated team statistics
+type TeamStats struct {
+	TeamID         uint  `json:"team_id"`
+	MembersCount   int64 `json:"members_count"`
+	ProjectsCount  int64 `json:"projects_count"`
+	BookmarksCount int64 `json:"bookmarks_count"`
+	NotesCount     int64 `json:"notes_count"`
+	TasksCount     int64 `json:"tasks_count"`
+	FilesCount     int64 `json:"files_count"`
+	RecentActivity int64 `json:"recent_activity"` // Activity in last 7 days
+}

backend/models/time_entry.go

@@ -0,0 +1,102 @@
+package models
+
+import (
+	"fmt"
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// TimeEntry represents a time tracking entry
+type TimeEntry struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// What is being tracked
+	TaskID     *uint     `json:"task_id,omitempty"`
+	Task       *Task     `json:"task,omitempty" gorm:"foreignKey:TaskID"`
+	BookmarkID *uint     `json:"bookmark_id,omitempty"`
+	Bookmark   *Bookmark `json:"bookmark,omitempty" gorm:"foreignKey:BookmarkID"`
+	NoteID     *uint     `json:"note_id,omitempty"`
+	Note       *Note     `json:"note,omitempty" gorm:"foreignKey:NoteID"`
+
+	// Time tracking data
+	StartTime   time.Time  `json:"start_time" gorm:"not null"`
+	EndTime     *time.Time `json:"end_time"`
+	Duration    *int       `json:"duration"` // Duration in seconds
+	Description string     `json:"description"`
+
+	// Organization and metadata
+	Tags     []Tag `json:"tags,omitempty" gorm:"many2many:time_entry_tags;"`
+	Billable bool  `json:"billable" gorm:"default:false"`
+
+	// Billing information
+	HourlyRate *float64 `json:"hourly_rate"`
+
+	// Timer state
+	IsRunning bool `json:"is_running" gorm:"default:false"`
+
+	// Additional metadata
+	Source string `json:"source" gorm:"default:manual"` // manual, auto, pomodoro
+}
+
+// BeforeCreate hook to set default values
+func (t *TimeEntry) BeforeCreate(tx *gorm.DB) error {
+	if t.StartTime.IsZero() {
+		t.StartTime = time.Now()
+	}
+	return nil
+}
+
+// BeforeUpdate hook to calculate duration when end time is set
+func (t *TimeEntry) BeforeUpdate(tx *gorm.DB) error {
+	if t.EndTime != nil && !t.EndTime.IsZero() {
+		duration := int(t.EndTime.Sub(t.StartTime).Seconds())
+		t.Duration = &duration
+		t.IsRunning = false
+	}
+	return nil
+}
+
+// Stop stops the timer and calculates duration
+func (t *TimeEntry) Stop() {
+	now := time.Now()
+	t.EndTime = &now
+	duration := int(now.Sub(t.StartTime).Seconds())
+	t.Duration = &duration
+	t.IsRunning = false
+}
+
+// GetDuration returns the duration in seconds
+func (t *TimeEntry) GetDuration() int {
+	if t.Duration != nil {
+		return *t.Duration
+	}
+	if t.IsRunning {
+		return int(time.Since(t.StartTime).Seconds())
+	}
+	if t.EndTime != nil {
+		return int(t.EndTime.Sub(t.StartTime).Seconds())
+	}
+	return 0
+}
+
+// GetFormattedDuration returns a human-readable duration
+func (t *TimeEntry) GetFormattedDuration() string {
+	duration := t.GetDuration()
+	hours := duration / 3600
+	minutes := (duration % 3600) / 60
+	seconds := duration % 60
+
+	if hours > 0 {
+		return fmt.Sprintf("%dh %dm %ds", hours, minutes, seconds)
+	} else if minutes > 0 {
+		return fmt.Sprintf("%dm %ds", minutes, seconds)
+	}
+	return fmt.Sprintf("%ds", seconds)
+}

backend/models/user.go

@@ -17,15 +17,52 @@ type User struct {
 	Username string `json:"username" gorm:"uniqueIndex;not null"`
 	Password string `json:"-" gorm:"not null"` // Hashed password
 	FullName string `json:"full_name"`
-	
+	Role     string `json:"role" gorm:"default:user"` // user, admin
+
+	// GitHub OAuth fields
+	GitHubID  int    `json:"github_id" gorm:"uniqueIndex"`
+	AvatarURL string `json:"avatar_url"`
+	Provider  string `json:"provider" gorm:"default:email"` // email, github
+
 	// Preferences
-	Theme       string `json:"theme" gorm:"default:dark"`
-	Language    string `json:"language" gorm:"default:en"`
-	Timezone    string `json:"timezone" gorm:"default:UTC"`
-	
+	Theme    string `json:"theme" gorm:"default:dark"`
+	Language string `json:"language" gorm:"default:en"`
+	Timezone string `json:"timezone" gorm:"default:UTC"`
+
+	// Social Profile Features
+	Bio         string       `json:"bio"`
+	Location    string       `json:"location"`
+	Website     string       `json:"website"`
+	Company     string       `json:"company"`
+	JobTitle    string       `json:"job_title"`
+	Skills      []Skill      `json:"skills,omitempty" gorm:"foreignKey:UserID"`
+	Projects    []Project    `json:"projects,omitempty" gorm:"foreignKey:UserID"`
+	SocialLinks []SocialLink `json:"social_links,omitempty" gorm:"foreignKey:UserID"`
+
+	// Security & 2FA
+	TOTPSecret    string     `json:"-" gorm:"column:totp_secret"` // Encrypted TOTP secret
+	TOTPEnabled   bool       `json:"totp_enabled" gorm:"default:false"`
+	BackupCodes   string     `json:"-" gorm:"column:backup_codes"` // Encrypted backup codes
+	LastLoginAt   *time.Time `json:"last_login_at"`
+	LoginAttempts int        `json:"login_attempts" gorm:"default:0"`
+	LockedUntil   *time.Time `json:"locked_until"`
+
+	// Privacy Settings
+	ProfileVisibility string `json:"profile_visibility" gorm:"default:public"` // public, private, friends
+	ShowEmail         bool   `json:"show_email" gorm:"default:false"`
+	ShowActivity      bool   `json:"show_activity" gorm:"default:true"`
+	AllowMessages     bool   `json:"allow_messages" gorm:"default:true"`
+
+	// Social Stats
+	FollowersCount  int `json:"followers_count" gorm:"default:0"`
+	FollowingCount  int `json:"following_count" gorm:"default:0"`
+	PublicBookmarks int `json:"public_bookmarks" gorm:"default:0"`
+	PublicNotes     int `json:"public_notes" gorm:"default:0"`
+
 	// Relationships
-	Bookmarks []Bookmark `json:"bookmarks,omitempty" gorm:"foreignKey:UserID"`
-	Tasks     []Task     `json:"tasks,omitempty" gorm:"foreignKey:UserID"`
-	Files     []File     `json:"files,omitempty" gorm:"foreignKey:UserID"`
-	Notes     []Note     `json:"notes,omitempty" gorm:"foreignKey:UserID"`
+	Bookmarks   []Bookmark  `json:"bookmarks,omitempty" gorm:"foreignKey:UserID"`
+	Tasks       []Task      `json:"tasks,omitempty" gorm:"foreignKey:UserID"`
+	Files       []File      `json:"files,omitempty" gorm:"foreignKey:UserID"`
+	Notes       []Note      `json:"notes,omitempty" gorm:"foreignKey:UserID"`
+	TimeEntries []TimeEntry `json:"time_entries,omitempty" gorm:"foreignKey:UserID"`
 }

backend/models/video_bookmark.go

@@ -0,0 +1,27 @@
+package models
+
+import (
+	"time"
+)
+
+// VideoBookmark represents a bookmarked YouTube video
+type VideoBookmark struct {
+	ID          uint      `json:"id" gorm:"primaryKey"`
+	VideoID     string    `json:"video_id" gorm:"uniqueIndex;not null"` // YouTube video ID
+	Title       string    `json:"title" gorm:"not null"`
+	Channel     string    `json:"channel" gorm:"not null"`
+	Thumbnail   string    `json:"thumbnail" gorm:"not null"`
+	URL         string    `json:"url" gorm:"not null"`
+	UserID      uint      `json:"user_id" gorm:"not null"` // Foreign key to User
+	Description string    `json:"description" gorm:"type:text"`
+	Tags        string    `json:"tags" gorm:"type:text"` // Comma-separated tags
+	IsWatched   bool      `json:"is_watched" gorm:"default:false"`
+	IsFavorite  bool      `json:"is_favorite" gorm:"default:false"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+// TableName specifies the table name for VideoBookmark
+func (VideoBookmark) TableName() string {
+	return "video_bookmarks"
+}

backend/models/web_scraping.go

@@ -0,0 +1,174 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// ScrapedContent represents content extracted from web pages
+type ScrapedContent struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Source information
+	URL           string `json:"url" gorm:"not null"`
+	Domain        string `json:"domain"`
+	Title         string `json:"title"`
+	Description   string `json:"description"`
+	Author        string `json:"author"`
+	PublishedDate *time.Time `json:"published_date"`
+	LastScraped   time.Time `json:"last_scraped"`
+
+	// Extracted content
+	Content       string `json:"content" gorm:"type:text"`
+	Summary       string `json:"summary" gorm:"type:text"`
+	Keywords      []string `json:"keywords" gorm:"serializer:json"`
+	Tags          []Tag `json:"tags,omitempty" gorm:"many2many:scraped_content_tags;"`
+	Images        []ScrapedImage `json:"images,omitempty" gorm:"foreignKey:ScrapedContentID"`
+	Links         []ScrapedLink `json:"links,omitempty" gorm:"foreignKey:ScrapedContentID"`
+	Videos        []ScrapedVideo `json:"videos,omitempty" gorm:"foreignKey:ScrapedContentID"`
+
+	// Content analysis
+	ContentType   string  `json:"content_type"` // article, blog, news, tutorial, documentation
+	WordCount     int     `json:"word_count"`
+	ReadingTime   int     `json:"reading_time"` // estimated minutes
+	Difficulty    string  `json:"difficulty"`  // beginner, intermediate, advanced
+	QualityScore  float64 `json:"quality_score"` // 0-100
+
+	// Processing status
+	Status        string `json:"status" gorm:"default:pending"` // pending, processing, completed, failed
+	ErrorMessage  string `json:"error_message"`
+	ProcessingLog string `json:"processing_log" gorm:"type:text"`
+
+	// Relationships
+	BookmarkID    *uint    `json:"bookmark_id,omitempty"`
+	Bookmark      *Bookmark `json:"bookmark,omitempty" gorm:"foreignKey:BookmarkID"`
+	NoteID        *uint    `json:"note_id,omitempty"`
+	Note          *Note    `json:"note,omitempty" gorm:"foreignKey:NoteID"`
+}
+
+// ScrapedImage represents images extracted from web pages
+type ScrapedImage struct {
+	ID               uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt        time.Time      `json:"created_at"`
+	UpdatedAt        time.Time      `json:"updated_at"`
+	DeletedAt        gorm.DeletedAt `json:"-" gorm:"index"`
+
+	ScrapedContentID uint           `json:"scraped_content_id" gorm:"not null;index"`
+	ScrapedContent   ScrapedContent `json:"scraped_content,omitempty" gorm:"foreignKey:ScrapedContentID"`
+
+	URL          string `json:"url"`
+	AltText      string `json:"alt_text"`
+	Title        string `json:"title"`
+	Width        int    `json:"width"`
+	Height       int    `json:"height"`
+	Format       string `json:"format"` // jpg, png, gif, svg, webp
+	Size         int64  `json:"size"`   // bytes in bytes
+	IsMainImage  bool   `json:"is_main_image" gorm:"default:false"`
+	LocalPath    string `json:"local_path"` // if downloaded
+	ThumbnailPath string `json:"thumbnail_path"` // if thumbnail generated
+}
+
+// ScrapedLink represents links extracted from web pages
+type ScrapedLink struct {
+	ID               uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt        time.Time      `json:"created_at"`
+	UpdatedAt        time.Time      `json:"updated_at"`
+	DeletedAt        gorm.DeletedAt `json:"-" gorm:"index"`
+
+	ScrapedContentID uint           `json:"scraped_content_id" gorm:"not null;index"`
+	ScrapedContent   ScrapedContent `json:"scraped_content,omitempty" gorm:"foreignKey:ScrapedContentID"`
+
+	URL         string `json:"url"`
+	Text        string `json:"text"`
+	Title       string `json:"title"`
+	LinkType    string `json:"link_type"` // internal, external, download, email
+	IsNoFollow  bool   `json:"is_no_follow"`
+	IsSponsored bool   `json:"is_sponsored"`
+	Domain      string `json:"domain"`
+}
+
+// ScrapedVideo represents videos extracted from web pages
+type ScrapedVideo struct {
+	ID               uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt        time.Time      `json:"created_at"`
+	UpdatedAt        time.Time      `json:"updated_at"`
+	DeletedAt        gorm.DeletedAt `json:"-" gorm:"index"`
+
+	ScrapedContentID uint           `json:"scraped_content_id" gorm:"not null;index"`
+	ScrapedContent   ScrapedContent `json:"scraped_content,omitempty" gorm:"foreignKey:ScrapedContentID"`
+
+	URL          string `json:"url"`
+	Title        string `json:"title"`
+	Description  string `json:"description"`
+	Duration     string `json:"duration"` // in format "HH:MM:SS"
+	Thumbnail    string `json:"thumbnail"`
+	Platform     string `json:"platform"` // youtube, vimeo, twitch, etc.
+	VideoID      string `json:"video_id"` // platform-specific ID
+	IsEmbeddable bool   `json:"is_embeddable"`
+}
+
+// ScrapingJob represents a web scraping job
+type ScrapingJob struct {
+	ID        uint           `json:"id" gorm:"primaryKey"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+
+	UserID uint `json:"user_id" gorm:"not null;index"`
+	User   User `json:"user,omitempty" gorm:"foreignKey:UserID"`
+
+	// Job details
+	URL           string `json:"url" gorm:"not null"`
+	JobType       string `json:"job_type" gorm:"default:full_scrape"` // full_scrape, content_only, images_only, links_only
+	Priority      string `json:"priority" gorm:"default:normal"` // low, normal, high, urgent
+	Status        string `json:"status" gorm:"default:pending"` // pending, processing, completed, failed, cancelled
+
+	// Processing options
+	ExtractImages    bool `json:"extract_images" gorm:"default:true"`
+	ExtractLinks     bool `json:"extract_links" gorm:"default:true"`
+	ExtractVideos    bool `json:"extract_videos" gorm:"default:true"`
+	GenerateSummary  bool `json:"generate_summary" gorm:"default:true"`
+	DownloadImages   bool `json:"download_images" gorm:"default:false"`
+	ExtractMetadata  bool `json:"extract_metadata" gorm:"default:true"`
+
+	// Timing and results
+	StartedAt   *time.Time `json:"started_at,omitempty"`
+	CompletedAt *time.Time `json:"completed_at,omitempty"`
+	Progress    float64    `json:"progress" gorm:"default:0"` // 0-100
+	ErrorMessage string    `json:"error_message"`
+
+	// Relationships
+	ScrapedContentID *uint          `json:"scraped_content_id,omitempty"`
+	ScrapedContent   *ScrapedContent `json:"scraped_content,omitempty" gorm:"foreignKey:ScrapedContentID"`
+}
+
+// BeforeCreate hooks
+func (s *ScrapedContent) BeforeCreate(tx *gorm.DB) error {
+	if s.Status == "" {
+		s.Status = "pending"
+	}
+	if s.LastScraped.IsZero() {
+		s.LastScraped = time.Now()
+	}
+	return nil
+}
+
+func (j *ScrapingJob) BeforeCreate(tx *gorm.DB) error {
+	if j.Status == "" {
+		j.Status = "pending"
+	}
+	if j.Priority == "" {
+		j.Priority = "normal"
+	}
+	if j.JobType == "" {
+		j.JobType = "full_scrape"
+	}
+	return nil
+}

backend/models/youtube_cache.go

@@ -0,0 +1,27 @@
+package models
+
+import (
+	"time"
+)
+
+// YouTubeChannelCache represents cached YouTube channel data
+type YouTubeChannelCache struct {
+	ID          int       `json:"id" gorm:"primaryKey"`
+	ChannelID   string    `json:"channel_id" gorm:"uniqueIndex"`
+	ChannelName string    `json:"channel_name"`
+	ChannelURL  string    `json:"channel_url"`
+	Videos      string    `json:"videos" gorm:"type:text"` // JSON array of videos
+	LastUpdated time.Time `json:"last_updated"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+// TableName specifies the table name for YouTubeChannelCache
+func (YouTubeChannelCache) TableName() string {
+	return "youtube_channel_cache"
+}
+
+// IsExpired checks if the cache is older than 2 hours
+func (y *YouTubeChannelCache) IsExpired() bool {
+	return time.Since(y.LastUpdated) > 2*time.Hour
+}