feat: implement semantic search, knowledge unit extraction, and visualization components

.agents/agents.md

@@ -1,6 +1,12 @@
+---
+type: agent-definitions
+version: 1.0
+---
+
 # Agent Personas
 
 ## NexusArchitect
+
 - **Role:** Lead Architect & Creative Technologist (.NET 10 & Blazor)
 - **Persona:** Professional, precise, Senior Full-Stack Engineer focused on performance and "invisible UI".
 - **Architecture Role:** Lead Clean Architecture Specialist.

src/NexusReader.Application/Abstractions/Persistence/IApplicationDbContext.cs

@@ -0,0 +1,15 @@
+using Microsoft.EntityFrameworkCore;
+using NexusReader.Domain.Entities;
+
+namespace NexusReader.Application.Abstractions.Persistence;
+
+public interface IApplicationDbContext
+{
+    DbSet<SemanticKnowledgeCache> SemanticKnowledgeCache { get; }
+    DbSet<KnowledgeUnit> KnowledgeUnits { get; }
+    DbSet<KnowledgeUnitLink> KnowledgeUnitLinks { get; }
+    DbSet<Ebook> Ebooks { get; }
+    DbSet<QuizResult> QuizResults { get; }
+    
+    Task<int> SaveChangesAsync(CancellationToken cancellationToken = default);
+}

src/NexusReader.Application/Abstractions/Services/IKnowledgeService.cs

@@ -7,6 +7,8 @@ public interface IKnowledgeService
 {
     Task<Result<KnowledgePacket>> GetKnowledgeAsync(string text, CancellationToken cancellationToken = default);
     Task<Result<KnowledgePacket>> GetGraphDataAsync(string text, CancellationToken cancellationToken = default);
+    Task<Result<KnowledgePacket>> GetKnowledgeMapAsync(string text, CancellationToken cancellationToken = default);
     Task<Result<KnowledgePacket>> GetSummaryAndQuizAsync(string text, CancellationToken cancellationToken = default);
+    Task<Result<List<RelevantContext>>> GetRelevantContextAsync(string query, string tenantId, CancellationToken cancellationToken = default);
     Task<Result> ClearCacheAsync(CancellationToken cancellationToken = default);
 }

src/NexusReader.Application/Commands/AI/VerifyGroundednessCommand.cs

@@ -0,0 +1,52 @@
+using FluentResults;
+using MediatR;
+using Microsoft.Extensions.AI;
+using NexusReader.Infrastructure.Services; // For PromptRegistry
+
+namespace NexusReader.Application.Commands.AI;
+
+public record VerifyGroundednessCommand(string Answer, string Context) : IRequest<Result<GroundednessResult>>;
+
+public record GroundednessResult(float Score, string Rationale, bool IsGrounded);
+
+public class VerifyGroundednessCommandHandler : IRequestHandler<VerifyGroundednessCommand, Result<GroundednessResult>>
+{
+    private readonly IChatClient _chatClient;
+
+    public VerifyGroundednessCommandHandler(IChatClient chatClient)
+    {
+        _chatClient = chatClient;
+    }
+
+    public async Task<Result<GroundednessResult>> Handle(VerifyGroundednessCommand request, CancellationToken cancellationToken)
+    {
+        var systemPrompt = @"
+        You are a Fact-Checking AI. Evaluate if the 'Answer' is supported by the 'Context'.
+        Rate the groundedness from 0.0 to 1.0.
+        Return ONLY a JSON object: { ""score"": 0.9, ""rationale"": ""string"", ""isGrounded"": true }
+        ";
+
+        var userPrompt = $"Context: {request.Context}\n\nAnswer: {request.Answer}";
+
+        try
+        {
+            var response = await _chatClient.GetResponseAsync(new List<ChatMessage>
+            {
+                new ChatMessage(ChatRole.System, systemPrompt),
+                new ChatMessage(ChatRole.User, userPrompt)
+            }, cancellationToken: cancellationToken);
+
+            var rawJson = response.Text?.Trim() ?? "{}";
+            // Simple cleanup if needed
+            rawJson = rawJson.Replace("```json", "").Replace("```", "").Trim();
+            
+            var result = System.Text.Json.JsonSerializer.Deserialize<GroundednessResult>(rawJson, new System.Text.Json.JsonSerializerOptions { PropertyNameCaseInsensitive = true });
+            
+            return result != null ? Result.Ok(result) : Result.Fail("Failed to parse groundedness result");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Failed to verify groundedness").CausedBy(ex));
+        }
+    }
+}

src/NexusReader.Application/DTOs/AI/KnowledgePacket.cs

@@ -13,10 +13,15 @@ public record QuizQuestion(
     [property: JsonPropertyName("correct_index")] int CorrectIndex
 );
 
+public record KnowledgeUnitDto(string Id, string Type, string Content, Dictionary<string, object>? Metadata = null);
+public record KnowledgeLinkDto(string Source, string Target, string Relation);
+
 public record KnowledgePacket
 {
     [JsonPropertyName("concepts")] public List<KeyConcept> Concepts { get; init; } = new();
     [JsonPropertyName("quizzes")] public List<QuizQuestion> Quizzes { get; init; } = new();
+    [JsonPropertyName("units")] public List<KnowledgeUnitDto> Units { get; init; } = new();
+    [JsonPropertyName("links")] public List<KnowledgeLinkDto> Links { get; init; } = new();
     [JsonPropertyName("graph")] public NexusReader.Application.Queries.Graph.GraphDataDto? Graph { get; init; }
     [JsonPropertyName("summary")] public string? Summary { get; init; }
 }

src/NexusReader.Application/DTOs/AI/RelevantContext.cs

@@ -0,0 +1,8 @@
+namespace NexusReader.Application.DTOs.AI;
+
+public class RelevantContext
+{
+    public string Text { get; set; } = string.Empty;
+    public string SourceId { get; set; } = string.Empty; // ContentHash or EbookTitle
+    public double Confidence { get; set; }
+}

src/NexusReader.Application/DTOs/AI/SemanticSearchResultDto.cs

@@ -0,0 +1,11 @@
+namespace NexusReader.Application.DTOs.AI;
+
+public class SemanticSearchResultDto
+{
+    public string ContentHash { get; set; } = string.Empty;
+    public string Snippet { get; set; } = string.Empty;
+    public string? UnitType { get; set; }
+    public float RelevanceScore { get; set; }
+    public string? SourceBookTitle { get; set; }
+    public Dictionary<string, object>? Metadata { get; set; } // Bonus context
+}

src/NexusReader.Application/NexusReader.Application.csproj

@@ -10,7 +10,10 @@
     <PackageReference Include="Mapster.DependencyInjection" Version="10.0.7" />
     <PackageReference Include="MediatR" Version="12.1.1" />
     <PackageReference Include="Microsoft.AspNetCore.Authorization" Version="10.0.7" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="10.0.7" />
+    <PackageReference Include="Microsoft.Extensions.AI" Version="10.5.0" />
     <PackageReference Include="Microsoft.Extensions.Identity.Core" Version="10.0.7" />
+    <PackageReference Include="Pgvector.EntityFrameworkCore" Version="0.2.1" />
   </ItemGroup>
 
   <PropertyGroup>

src/NexusReader.Application/Queries/Graph/GraphViewModels.cs

@@ -1,7 +1,7 @@
 namespace NexusReader.Application.Queries.Graph;
 
-public record GraphNodeDto(string Id, string Label, string Group);
+public record GraphNodeDto(string Id, string Label, string Group, string? Type = null);
-public record GraphLinkDto(string Source, string Target, int Value);
+public record GraphLinkDto(string Source, string Target, string RelationType, int Value = 1);
 public record GraphDataDto
 {
     public List<GraphNodeDto> Nodes { get; init; } = new();

src/NexusReader.Application/Queries/Library/SearchLibrarySemanticallyQuery.cs

@@ -0,0 +1,114 @@
+using FluentResults;
+using Mapster;
+using MediatR;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.AI;
+using NexusReader.Application.DTOs.AI;
+using NexusReader.Application.Abstractions.Persistence;
+using Pgvector.EntityFrameworkCore;
+
+namespace NexusReader.Application.Queries.Library;
+
+public record SearchLibrarySemanticallyQuery(string QueryText, string TenantId, int Limit = 5) 
+    : IRequest<Result<List<SemanticSearchResultDto>>>;
+
+public class SearchLibrarySemanticallyQueryHandler : IRequestHandler<SearchLibrarySemanticallyQuery, Result<List<SemanticSearchResultDto>>>
+{
+    private readonly IApplicationDbContext _dbContext;
+    private readonly IEmbeddingGenerator<string, Embedding<float>> _embeddingGenerator;
+
+    public SearchLibrarySemanticallyQueryHandler(
+        IApplicationDbContext dbContext,
+        IEmbeddingGenerator<string, Embedding<float>> embeddingGenerator)
+    {
+        _dbContext = dbContext;
+        _embeddingGenerator = embeddingGenerator;
+    }
+
+    public async Task<Result<List<SemanticSearchResultDto>>> Handle(SearchLibrarySemanticallyQuery request, CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(request.QueryText))
+        {
+            return Result.Fail("Query text cannot be empty.");
+        }
+
+        try
+        {
+            // 1. Generate embedding for user query
+            var embeddingResponse = await _embeddingGenerator.GenerateAsync(new[] { request.QueryText }, cancellationToken: cancellationToken);
+            var queryVector = embeddingResponse.First().Vector.ToArray();
+
+            // 2. Perform Cosine Similarity Search on Knowledge Units
+            var candidates = await _dbContext.KnowledgeUnits
+                .AsNoTracking()
+                .Where(x => (x.TenantId == request.TenantId || x.TenantId == "global") && x.Vector != null)
+                .OrderBy(x => x.Vector!.CosineDistance(queryVector))
+                .Take(request.Limit)
+                .ToListAsync(cancellationToken);
+
+            if (!candidates.Any())
+            {
+                // Fallback to legacy cache if no granular units found
+                var legacyResults = await _dbContext.SemanticKnowledgeCache
+                    .AsNoTracking()
+                    .Where(x => x.TenantId == request.TenantId && x.Vector != null)
+                    .OrderBy(x => x.Vector!.CosineDistance(queryVector))
+                    .Take(request.Limit)
+                    .ToListAsync(cancellationToken);
+
+                return Result.Ok(legacyResults.Select(r => new SemanticSearchResultDto
+                {
+                    ContentHash = r.ContentHash,
+                    Snippet = r.OriginalText,
+                    RelevanceScore = (float)(1 - r.Vector!.CosineDistance(queryVector))
+                }).ToList());
+            }
+
+            // 3. Graph Expansion: Pull related units (e.g. Definitions, Next steps)
+            var candidateIds = candidates.Select(c => c.Id).ToList();
+            var links = await _dbContext.KnowledgeUnitLinks
+                .AsNoTracking()
+                .Where(l => candidateIds.Contains(l.SourceUnitId) && (l.RelationType == "Defines" || l.RelationType == "Next"))
+                .ToListAsync(cancellationToken);
+
+            var relatedIds = links.Select(l => l.TargetUnitId).Distinct().ToList();
+            var relatedUnits = await _dbContext.KnowledgeUnits
+                .AsNoTracking()
+                .Where(u => relatedIds.Contains(u.Id))
+                .ToDictionaryAsync(u => u.Id, cancellationToken);
+
+            // 4. Mapping with Context Enrichment
+            var dtos = candidates.Select(c => 
+            {
+                var dto = new SemanticSearchResultDto
+                {
+                    ContentHash = c.Id,
+                    Snippet = c.Content,
+                    UnitType = c.Type.ToString(),
+                    RelevanceScore = (float)(1 - c.Vector!.CosineDistance(queryVector)),
+                    Metadata = string.IsNullOrEmpty(c.MetadataJson) 
+                        ? null 
+                        : System.Text.Json.JsonSerializer.Deserialize<Dictionary<string, object>>(c.MetadataJson)
+                };
+
+                // Enrich snippet with definitions if present
+                var unitLinks = links.Where(l => l.SourceUnitId == c.Id && l.RelationType == "Defines").ToList();
+                if (unitLinks.Any())
+                {
+                    var definitions = unitLinks
+                        .Where(l => relatedUnits.ContainsKey(l.TargetUnitId))
+                        .Select(l => relatedUnits[l.TargetUnitId].Content);
+                    dto.Snippet = $"[Context: {string.Join("; ", definitions)}]\n{dto.Snippet}";
+                }
+
+                return dto;
+            }).ToList();
+
+            return Result.Ok(dtos);
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Failed to perform semantic search").CausedBy(ex));
+        }
+    }
+}

src/NexusReader.Domain/Entities/KnowledgeUnit.cs

@@ -0,0 +1,41 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using NexusReader.Domain.Enums;
+
+namespace NexusReader.Domain.Entities;
+
+public class KnowledgeUnit
+{
+    [Key]
+    [MaxLength(128)]
+    public string Id { get; set; } = string.Empty; // Hash(Source + Content + Version)
+
+    [Required]
+    [MaxLength(128)]
+    public string SourceId { get; set; } = string.Empty;
+
+    [Required]
+    [MaxLength(50)]
+    public string Version { get; set; } = "1.0";
+
+    [Required]
+    public KnowledgeUnitType Type { get; set; }
+
+    [Required]
+    public string Content { get; set; } = string.Empty;
+
+    public string? MetadataJson { get; set; } // e.g. { "page": 1, "path": "Chapter 1 > Intro" }
+
+    [Required]
+    [MaxLength(128)]
+    public string TenantId { get; set; } = string.Empty;
+
+    [Column(TypeName = "vector(768)")] // Default for text-embedding-004
+    public float[]? Vector { get; set; }
+
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+    // Relationships
+    public ICollection<KnowledgeUnitLink> OutgoingLinks { get; set; } = new List<KnowledgeUnitLink>();
+    public ICollection<KnowledgeUnitLink> IncomingLinks { get; set; } = new List<KnowledgeUnitLink>();
+}

src/NexusReader.Domain/Entities/KnowledgeUnitLink.cs

@@ -0,0 +1,28 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace NexusReader.Domain.Entities;
+
+public class KnowledgeUnitLink
+{
+    [Key]
+    public int Id { get; set; }
+
+    [Required]
+    [MaxLength(128)]
+    public string SourceUnitId { get; set; } = string.Empty;
+
+    [Required]
+    [MaxLength(128)]
+    public string TargetUnitId { get; set; } = string.Empty;
+
+    [Required]
+    [MaxLength(50)]
+    public string RelationType { get; set; } = "References"; // e.g., "Next", "Defines", "Contains"
+
+    [ForeignKey(nameof(SourceUnitId))]
+    public KnowledgeUnit SourceUnit { get; set; } = null!;
+
+    [ForeignKey(nameof(TargetUnitId))]
+    public KnowledgeUnit TargetUnit { get; set; } = null!;
+}

src/NexusReader.Domain/Entities/SemanticKnowledgeCache.cs

@@ -1,4 +1,5 @@
 using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
 
 namespace NexusReader.Domain.Entities;
 
@@ -11,6 +12,9 @@ public class SemanticKnowledgeCache
     [Required]
     public string JsonData { get; set; } = string.Empty;
 
+    [Required]
+    public string OriginalText { get; set; } = string.Empty;
+
     [Required]
     [MaxLength(50)]
     public string ModelId { get; set; } = "gemini-1.5-flash";
@@ -19,5 +23,12 @@ public class SemanticKnowledgeCache
     [MaxLength(10)]
     public string PromptVersion { get; set; } = "1.0";
 
+    [Required]
+    [MaxLength(128)]
+    public string TenantId { get; set; } = string.Empty;
+
+    [Column(TypeName = "vector(1536)")] // text-embedding-004 has 768 or 1536 dims, assuming 1536 for high-fidelity
+    public float[]? Vector { get; set; }
+
     public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
 }

src/NexusReader.Domain/Enums/KnowledgeUnitType.cs

@@ -0,0 +1,12 @@
+namespace NexusReader.Domain.Enums;
+
+public enum KnowledgeUnitType
+{
+    Section,
+    Table,
+    Definition,
+    ProcedureStep,
+    PolicyRule,
+    KeyConcept,
+    Snippet
+}

src/NexusReader.Infrastructure/Persistence/AppDbContext.cs

@@ -1,21 +1,26 @@
 using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore;
 using NexusReader.Domain.Entities;
+using NexusReader.Application.Abstractions.Persistence;
 
 namespace NexusReader.Infrastructure.Persistence;
 
-public class AppDbContext : IdentityDbContext<NexusUser>
+public class AppDbContext : IdentityDbContext<NexusUser>, IApplicationDbContext
 {
     public AppDbContext(DbContextOptions<AppDbContext> options) : base(options)
     {
     }
 
     public DbSet<SemanticKnowledgeCache> SemanticKnowledgeCache => Set<SemanticKnowledgeCache>();
+    public DbSet<KnowledgeUnit> KnowledgeUnits => Set<KnowledgeUnit>();
+    public DbSet<KnowledgeUnitLink> KnowledgeUnitLinks => Set<KnowledgeUnitLink>();
     public DbSet<Ebook> Ebooks => Set<Ebook>();
     public DbSet<QuizResult> QuizResults => Set<QuizResult>();
 
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
+        modelBuilder.HasPostgresExtension("pgvector");
+
         modelBuilder.Entity<NexusUser>(entity =>
         {
             entity.Property(u => u.LastReadPageId).HasMaxLength(255);
@@ -28,6 +33,30 @@ public class AppDbContext : IdentityDbContext<NexusUser>
         {
             entity.HasKey(e => e.ContentHash);
             entity.HasIndex(e => e.ContentHash).IsUnique();
+            entity.HasIndex(e => e.TenantId);
+            entity.Property(e => e.Vector).HasColumnType("vector(1536)"); // Standard for many models
+        });
+
+        modelBuilder.Entity<KnowledgeUnit>(entity =>
+        {
+            entity.HasKey(e => e.Id);
+            entity.HasIndex(e => e.TenantId);
+            entity.HasIndex(e => e.SourceId);
+            entity.Property(e => e.Vector).HasColumnType("vector(768)"); // text-embedding-004
+        });
+
+        modelBuilder.Entity<KnowledgeUnitLink>(entity =>
+        {
+            entity.HasKey(e => e.Id);
+            entity.HasOne(e => e.SourceUnit)
+                .WithMany(u => u.OutgoingLinks)
+                .HasForeignKey(e => e.SourceUnitId)
+                .OnDelete(DeleteBehavior.Cascade);
+
+            entity.HasOne(e => e.TargetUnit)
+                .WithMany(u => u.IncomingLinks)
+                .HasForeignKey(e => e.TargetUnitId)
+                .OnDelete(DeleteBehavior.Cascade);
         });
 
         modelBuilder.Entity<Ebook>(entity =>

src/NexusReader.Infrastructure/Services/KnowledgeService.cs

@@ -12,12 +12,14 @@ using Polly;
 using Polly.Registry;
 using Microsoft.Extensions.Options;
 using NexusReader.Infrastructure.Configuration;
+using Pgvector.EntityFrameworkCore;
 
 namespace NexusReader.Infrastructure.Services;
 
 public class KnowledgeService : IKnowledgeService
 {
     private readonly IChatClient _chatClient;
+    private readonly IEmbeddingGenerator<string, Embedding<float>> _embeddingGenerator;
     private readonly AppDbContext _dbContext;
     private readonly ResiliencePipeline _retryPipeline;
     private readonly AiSettings _settings;
@@ -26,11 +28,13 @@ public class KnowledgeService : IKnowledgeService
 
     public KnowledgeService(
         IChatClient chatClient,
+        IEmbeddingGenerator<string, Embedding<float>> embeddingGenerator,
         AppDbContext dbContext,
         ResiliencePipelineProvider<string> pipelineProvider,
         IOptions<AiSettings> settings)
     {
         _chatClient = chatClient;
+        _embeddingGenerator = embeddingGenerator;
         _dbContext = dbContext;
         _retryPipeline = pipelineProvider.GetPipeline("ai-retry");
         _settings = settings.Value;
@@ -54,6 +58,11 @@ public class KnowledgeService : IKnowledgeService
         return await GetKnowledgeInternalAsync(text, PromptRegistry.SummaryAndQuizPrompt, "summary_quiz", cancellationToken);
     }
 
+    public async Task<Result<KnowledgePacket>> GetKnowledgeMapAsync(string text, CancellationToken cancellationToken = default)
+    {
+        return await GetKnowledgeInternalAsync(text, PromptRegistry.KM_ExtractionPrompt, "km_map", cancellationToken);
+    }
+
     private async Task<Result<KnowledgePacket>> GetKnowledgeInternalAsync(string text, string systemPrompt, string cacheSuffix, CancellationToken cancellationToken)
     {
         if (string.IsNullOrWhiteSpace(text))
@@ -115,18 +124,47 @@ public class KnowledgeService : IKnowledgeService
                 var knowledgePacket = JsonSerializer.Deserialize<KnowledgePacket>(jsonResponse, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
                 if (knowledgePacket == null) return Result.Fail("Failed to deserialize AI response.");
                 
-                // 3. Save to Cache
+                // 3. Generate Embedding if not present
+                float[]? vector = null;
+                try
+                {
+                    var embeddingResponse = await _retryPipeline.ExecuteAsync(async ct => 
+                        await _embeddingGenerator.GenerateAsync(new[] { normalizedText }, cancellationToken: ct), cancellationToken);
+                    vector = embeddingResponse.First().Vector.ToArray();
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine($"[KnowledgeService] Embedding Error: {ex.Message}");
+                    // We continue even if embedding fails, as the primary goal was knowledge extraction
+                }
+
+                // 4. Save to Cache
                 var cacheEntry = new SemanticKnowledgeCache
                 {
                     ContentHash = hash,
                     JsonData = jsonResponse,
+                    OriginalText = normalizedText,
                     ModelId = _settings.Model,
                     PromptVersion = PromptVersion,
+                    TenantId = "global", // Default for shared cache, should be overridden by caller context if possible
+                    Vector = vector,
                     CreatedAt = DateTime.UtcNow
                 };
 
                 if (cached == null) _dbContext.SemanticKnowledgeCache.Add(cacheEntry);
-                else { cached.JsonData = jsonResponse; cached.CreatedAt = DateTime.UtcNow; }
+                else 
+                { 
+                    cached.JsonData = jsonResponse; 
+                    cached.OriginalText = normalizedText;
+                    cached.Vector = vector;
+                    cached.CreatedAt = DateTime.UtcNow; 
+                }
+
+                // 5. Process KM-RAG Units and Links if present
+                if (knowledgePacket.Units.Any())
+                {
+                    await ProcessKnowledgeUnitsAsync(knowledgePacket, "global", cancellationToken);
+                }
 
                 await _dbContext.SaveChangesAsync(cancellationToken);
                 return Result.Ok(knowledgePacket);
@@ -143,6 +181,75 @@ public class KnowledgeService : IKnowledgeService
         }
     }
 
+    private async Task ProcessKnowledgeUnitsAsync(KnowledgePacket packet, string tenantId, CancellationToken cancellationToken)
+    {
+        foreach (var unitDto in packet.Units)
+        {
+            var unitId = unitDto.Id;
+            var existing = await _dbContext.KnowledgeUnits.FindAsync(new object[] { unitId }, cancellationToken);
+
+            var unit = existing ?? new KnowledgeUnit { Id = unitId, TenantId = tenantId };
+            unit.Type = Enum.TryParse<NexusReader.Domain.Enums.KnowledgeUnitType>(unitDto.Type, true, out var type) ? type : NexusReader.Domain.Enums.KnowledgeUnitType.Snippet;
+            unit.Content = unitDto.Content;
+            unit.SourceId = "extracted"; // Should be passed from context
+            unit.MetadataJson = JsonSerializer.Serialize(unitDto.Metadata);
+
+            // Generate unit-specific embedding for granular retrieval
+            try
+            {
+                var emb = await _embeddingGenerator.GenerateAsync(new[] { unit.Content }, cancellationToken: cancellationToken);
+                unit.Vector = emb.First().Vector.ToArray();
+            }
+            catch { /* Ignore embedding errors for now */ }
+
+            if (existing == null) _dbContext.KnowledgeUnits.Add(unit);
+        }
+
+        foreach (var linkDto in packet.Links)
+        {
+            var link = new KnowledgeUnitLink
+            {
+                SourceUnitId = linkDto.Source,
+                TargetUnitId = linkDto.Target,
+                RelationType = linkDto.Relation
+            };
+            _dbContext.KnowledgeUnitLinks.Add(link);
+        }
+    }
+
+    public async Task<Result<List<RelevantContext>>> GetRelevantContextAsync(string query, string tenantId, CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(query)) return Result.Fail("Query is empty.");
+
+        try
+        {
+            // 1. Generate embedding for query
+            var embeddingResponse = await _retryPipeline.ExecuteAsync(async ct => 
+                await _embeddingGenerator.GenerateAsync(new[] { query }, cancellationToken: ct), cancellationToken);
+            var queryVector = embeddingResponse.First().Vector.ToArray();
+
+            // 2. Search using pgvector
+            var results = await _dbContext.SemanticKnowledgeCache
+                .AsNoTracking()
+                .Where(x => (x.TenantId == tenantId || x.TenantId == "global") && x.Vector != null)
+                .OrderBy(x => x.Vector!.CosineDistance(queryVector))
+                .Take(5)
+                .Select(x => new RelevantContext
+                {
+                    Text = x.OriginalText,
+                    SourceId = x.ContentHash,
+                    Confidence = 1 - x.Vector!.CosineDistance(queryVector)
+                })
+                .ToListAsync(cancellationToken);
+
+            return Result.Ok(results);
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Failed to retrieve relevant context").CausedBy(ex));
+        }
+    }
+
     public async Task<Result> ClearCacheAsync(CancellationToken cancellationToken = default)
     {
         try

src/NexusReader.Infrastructure/Services/PromptRegistry.cs

@@ -21,4 +21,13 @@ public static class PromptRegistry
     public const string SummaryAndQuizPrompt = 
         "You are an expert educator. Provide a concise summary of the text and generate a challenging quiz (3-5 questions). " +
         "Return ONLY minified JSON. Schema: { \"summary\": \"string\", \"quizzes\": [ { \"question\": \"string\", \"options\": [ \"string\" ], \"correct_index\": 0 } ] }";
+
+    public const string KM_ExtractionPrompt = 
+        "You are an expert at Knowledge Engineering. Segment the provided text into discrete Knowledge Units. " +
+        "Identify 'units' (sections, tables, definitions, rules) and 'links' (how they relate). " +
+        "CRITICAL: Units must be granular. " +
+        "Schema: { " +
+        "\"units\": [ { \"id\": \"string\", \"type\": \"Section|Table|Definition|Rule\", \"content\": \"string\", \"metadata\": { \"page\": 0 } } ], " +
+        "\"links\": [ { \"source\": \"string\", \"target\": \"string\", \"relation\": \"Next|Defines|Contains|References\" } ] " +
+        "}.";
 }

src/NexusReader.UI.Shared/Components/Atoms/NexusSearchBox.razor

@@ -0,0 +1,39 @@
+@namespace NexusReader.UI.Shared.Components.Atoms
+
+<div class="nexus-search-container @(IsActive ? "active" : "")">
+    <div class="search-wrapper">
+        <i class="nexus-icon @IconClass"></i>
+        <input type="text" 
+               @bind="SearchValue" 
+               @bind:event="oninput"
+               @onkeypress="HandleKeyPress"
+               placeholder="@Placeholder" 
+               class="nexus-search-input" />
+        @if (!string.IsNullOrEmpty(SearchValue))
+        {
+            <button class="clear-btn" @onclick="ClearSearch">×</button>
+        }
+    </div>
+</div>
+
+@code {
+    [Parameter] public string Placeholder { get; set; } = "Search your library...";
+    [Parameter] public string IconClass { get; set; } = "bi bi-search";
+    [Parameter] public EventCallback<string> OnSearch { get; set; }
+    
+    private string SearchValue { get; set; } = string.Empty;
+    private bool IsActive => !string.IsNullOrEmpty(SearchValue);
+
+    private async Task HandleKeyPress(KeyboardEventArgs e)
+    {
+        if (e.Key == "Enter")
+        {
+            await OnSearch.InvokeAsync(SearchValue);
+        }
+    }
+
+    private void ClearSearch()
+    {
+        SearchValue = string.Empty;
+    }
+}

src/NexusReader.UI.Shared/Components/Atoms/NexusSearchBox.razor.css

@@ -0,0 +1,57 @@
+.nexus-search-container {
+    width: 100%;
+    max-width: 500px;
+    margin: 1rem auto;
+    transition: all 0.3s ease;
+}
+
+.search-wrapper {
+    position: relative;
+    display: flex;
+    align-items: center;
+    background: var(--nexus-card, #141414);
+    border: 1px solid rgba(255, 255, 255, 0.1);
+    border-radius: 12px;
+    padding: 0.5rem 1rem;
+    transition: border-color 0.3s ease, box-shadow 0.3s ease;
+}
+
+.nexus-search-container.active .search-wrapper,
+.search-wrapper:focus-within {
+    border-color: var(--nexus-neon, #00ff99);
+    box-shadow: 0 0 15px rgba(0, 255, 153, 0.2);
+}
+
+.nexus-icon {
+    color: rgba(255, 255, 255, 0.5);
+    margin-right: 0.75rem;
+    font-size: 1.1rem;
+}
+
+.nexus-search-input {
+    flex: 1;
+    background: transparent;
+    border: none;
+    color: white;
+    font-family: 'Inter', sans-serif;
+    font-size: 0.95rem;
+    outline: none;
+}
+
+.nexus-search-input::placeholder {
+    color: rgba(255, 255, 255, 0.3);
+}
+
+.clear-btn {
+    background: transparent;
+    border: none;
+    color: rgba(255, 255, 255, 0.4);
+    font-size: 1.2rem;
+    cursor: pointer;
+    padding: 0 0.5rem;
+    transition: color 0.2s ease;
+}
+
+.clear-btn:hover {
+    color: var(--nexus-neon, #00ff99);
+}

src/NexusReader.UI.Shared/Components/Molecules/GroundednessBadge.razor

@@ -0,0 +1,84 @@
+@using MediatR
+@using NexusReader.Application.Commands.AI
+@using NexusReader.UI.Shared.Components.Atoms
+@inject IMediator Mediator
+
+<div class="groundedness-badge @GetStatusClass()" title="@_result?.Rationale">
+    @if (_isChecking)
+    {
+        <span class="shimmer">Weryfikacja...</span>
+    }
+    else if (_result != null)
+    {
+        <NexusIcon Name="@(GetIcon())" Size="14" />
+        <span>@((_result.Score * 100).ToString("0"))% Grounded</span>
+    }
+</div>
+
+<style>
+    .groundedness-badge {
+        display: inline-flex;
+        align-items: center;
+        gap: 6px;
+        padding: 4px 8px;
+        border-radius: 12px;
+        font-size: 0.75rem;
+        font-weight: 600;
+        background: rgba(255,255,255,0.05);
+        border: 1px solid rgba(255,255,255,0.1);
+        transition: all 0.3s ease;
+    }
+
+    .groundedness-badge.status-high { color: var(--nexus-neon); border-color: var(--nexus-neon); }
+    .groundedness-badge.status-medium { color: #ffaa00; border-color: #ffaa00; }
+    .groundedness-badge.status-low { color: #ff4444; border-color: #ff4444; }
+
+    .shimmer { opacity: 0.6; }
+</style>
+
+@code {
+    [Parameter] public string Answer { get; set; } = string.Empty;
+    [Parameter] public string Context { get; set; } = string.Empty;
+
+    private GroundednessResult? _result;
+    private bool _isChecking;
+
+    protected override async Task OnParametersSetAsync()
+    {
+        if (!string.IsNullOrEmpty(Answer) && !string.IsNullOrEmpty(Context) && _result == null)
+        {
+            await RunCheck();
+        }
+    }
+
+    private async Task RunCheck()
+    {
+        _isChecking = true;
+        StateHasChanged();
+
+        var res = await Mediator.Send(new VerifyGroundednessCommand(Answer, Context));
+        if (res.IsSuccess)
+        {
+            _result = res.Value;
+        }
+
+        _isChecking = false;
+        StateHasChanged();
+    }
+
+    private string GetStatusClass()
+    {
+        if (_result == null) return "";
+        if (_result.Score >= 0.8) return "status-high";
+        if (_result.Score >= 0.5) return "status-medium";
+        return "status-low";
+    }
+
+    private string GetIcon()
+    {
+        if (_result == null) return "help";
+        if (_result.Score >= 0.8) return "check-circle";
+        if (_result.Score >= 0.5) return "info-circle";
+        return "alert-triangle";
+    }
+}

src/NexusReader.UI.Shared/Components/Organisms/GlobalIntelligencePanel.razor

@@ -0,0 +1,61 @@
+@using NexusReader.Application.DTOs.AI
+@using NexusReader.UI.Shared.Components.Atoms
+@namespace NexusReader.UI.Shared.Components.Organisms
+
+<div class="global-intelligence-panel">
+    <div class="panel-header">
+        <h3><i class="bi bi-cpu"></i> Global Intelligence</h3>
+        <p>Semantic search across your library</p>
+    </div>
+
+    <NexusSearchBox Placeholder="Ask a question about your books..." OnSearch="HandleSearch" />
+
+    <div class="results-container">
+        @if (IsLoading)
+        {
+            <div class="loading-state">
+                <div class="nexus-spinner"></div>
+                <span>Analyzing your library...</span>
+            </div>
+        }
+        else if (Results != null && Results.Any())
+        {
+            @foreach (var result in Results)
+            {
+                <div class="search-result-item">
+                    <div class="result-meta">
+                        <span class="relevance">@(Math.Round(result.RelevanceScore * 100))% Relevant</span>
+                        @if (!string.IsNullOrEmpty(result.SourceBookTitle))
+                        {
+                            <span class="source">in <strong>@result.SourceBookTitle</strong></span>
+                        }
+                    </div>
+                    <div class="result-snippet">
+                        @result.Snippet
+                    </div>
+                </div>
+            }
+        }
+        else if (HasSearched)
+        {
+            <div class="empty-state">
+                <i class="bi bi-search"></i>
+                <p>No semantic matches found.</p>
+            </div>
+        }
+    </div>
+</div>
+
+@code {
+    [Parameter] public List<SemanticSearchResultDto>? Results { get; set; }
+    [Parameter] public bool IsLoading { get; set; }
+    [Parameter] public EventCallback<string> OnPerformSearch { get; set; }
+
+    private bool HasSearched { get; set; }
+
+    private async Task HandleSearch(string query)
+    {
+        HasSearched = true;
+        await OnPerformSearch.InvokeAsync(query);
+    }
+}

src/NexusReader.UI.Shared/Components/Organisms/GlobalIntelligencePanel.razor.css

@@ -0,0 +1,94 @@
+.global-intelligence-panel {
+    background: var(--nexus-bg, #0a0a0a);
+    border-left: 1px solid rgba(255, 255, 255, 0.05);
+    height: 100%;
+    display: flex;
+    flex-direction: column;
+    padding: 1.5rem;
+}
+
+.panel-header h3 {
+    margin: 0;
+    color: var(--nexus-neon, #00ff99);
+    font-size: 1.25rem;
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+}
+
+.panel-header p {
+    color: rgba(255, 255, 255, 0.5);
+    font-size: 0.85rem;
+    margin: 0.25rem 0 1.5rem 0;
+}
+
+.results-container {
+    flex: 1;
+    overflow-y: auto;
+    margin-top: 1rem;
+    padding-right: 0.5rem;
+}
+
+.search-result-item {
+    background: var(--nexus-card, #141414);
+    border-radius: 8px;
+    padding: 1rem;
+    margin-bottom: 1rem;
+    border: 1px solid rgba(255, 255, 255, 0.05);
+    transition: transform 0.2s ease, border-color 0.2s ease;
+}
+
+.search-result-item:hover {
+    transform: translateX(4px);
+    border-color: rgba(0, 255, 153, 0.3);
+}
+
+.result-meta {
+    display: flex;
+    justify-content: space-between;
+    font-size: 0.75rem;
+    margin-bottom: 0.5rem;
+}
+
+.relevance {
+    color: var(--nexus-neon, #00ff99);
+    font-weight: 600;
+}
+
+.source {
+    color: rgba(255, 255, 255, 0.4);
+}
+
+.result-snippet {
+    color: rgba(255, 255, 255, 0.8);
+    font-size: 0.9rem;
+    line-height: 1.5;
+    display: -webkit-box;
+    -webkit-line-clamp: 4;
+    -webkit-box-orient: vertical;
+    overflow: hidden;
+}
+
+.loading-state, .empty-state {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    height: 200px;
+    color: rgba(255, 255, 255, 0.3);
+    text-align: center;
+}
+
+.nexus-spinner {
+    width: 30px;
+    height: 30px;
+    border: 2px solid rgba(0, 255, 153, 0.1);
+    border-top-color: var(--nexus-neon, #00ff99);
+    border-radius: 50%;
+    animation: spin 1s linear infinite;
+    margin-bottom: 1rem;
+}
+
+@keyframes spin {
+    to { transform: rotate(360deg); }
+}

src/NexusReader.UI.Shared/wwwroot/js/knowledgeGraph.js

@@ -122,13 +122,19 @@ export function updateData(data) {
     // Update Links
     link = rootGroup.select(".links-layer")
         .selectAll("path")
-        .data(data.links, d => d.source + "-" + d.target)
+        .data(data.links, d => d.source + "-" + d.target + "-" + d.relationType)
         .join(
             enter => enter.append("path")
-                .attr("stroke", "rgba(255,255,255,0.05)")
+                .attr("stroke", d => {
+                    if (d.relationType === 'Defines') return 'var(--nexus-accent)';
+                    if (d.relationType === 'Next') return 'rgba(255,255,255,0.2)';
+                    if (d.relationType === 'Contains') return 'var(--nexus-neon)';
+                    return 'rgba(255,255,255,0.1)';
+                })
                 .attr("fill", "none")
-                .attr("stroke-width", 1.5)
+                .attr("stroke-width", d => d.relationType === 'Defines' ? 2 : 1)
-                .call(e => e.transition().duration(500).attr("stroke", "rgba(255,255,255,0.1)")),
+                .attr("stroke-dasharray", d => d.relationType === 'References' ? "5,5" : "0")
+                .call(e => e.transition().duration(500).attr("opacity", 1)),
             update => update,
             exit => exit.remove()
         );
@@ -150,7 +156,12 @@ export function updateData(data) {
 
                 g.append("circle")
                     .attr("r", 30)
-                    .attr("fill", "url(#nebulaGlow)")
+                    .attr("fill", d => {
+                        if (d.type === 'Definition') return 'var(--nexus-accent)';
+                        if (d.type === 'Table') return 'var(--nexus-neon)';
+                        if (d.type === 'Rule') return '#ff4444';
+                        return "url(#nebulaGlow)";
+                    })
                     .attr("opacity", 0)
                     .transition().duration(1000).attr("opacity", d => d.group === 'current' ? 0.6 : 0.2);
 
@@ -162,14 +173,18 @@ export function updateData(data) {
                     .attr("height", 24)
                     .attr("rx", 12)
                     .attr("fill", "rgba(20, 20, 20, 0.9)")
-                    .attr("stroke", "rgba(255, 255, 255, 0.1)")
+                    .attr("stroke", d => {
+                        if (d.type === 'Definition') return 'var(--nexus-accent)';
+                        if (d.type === 'Rule') return '#ff4444';
+                        return "rgba(255, 255, 255, 0.1)";
+                    })
                     .attr("stroke-width", 1);
 
                 g.append("text")
                     .text(d => d.label)
                     .attr("text-anchor", "middle")
                     .attr("y", 4)
-                    .attr("fill", "#ccc")
+                    .attr("fill", d => d.type === 'Definition' ? 'var(--nexus-accent)' : '#ccc')
                     .attr("font-size", "0.8rem");
                 
                 return g;

src/NexusReader.Web.Client/Services/WasmKnowledgeService.cs

@@ -29,6 +29,26 @@ public class WasmKnowledgeService : IKnowledgeService
         return await CallKnowledgeApiAsync("/api/knowledge/summary", text, cancellationToken);
     }
 
+    public async Task<Result<List<RelevantContext>>> GetRelevantContextAsync(string query, string tenantId, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var response = await _httpClient.PostAsJsonAsync("/api/knowledge/relevant", new { query, tenantId }, cancellationToken);
+            if (response.IsSuccessStatusCode)
+            {
+                var context = await response.Content.ReadFromJsonAsync<List<RelevantContext>>(cancellationToken: cancellationToken);
+                return context != null ? Result.Ok(context) : Result.Fail("Failed to deserialize relevant context.");
+            }
+
+            var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
+            return Result.Fail($"Server error ({response.StatusCode}): {errorBody}");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error($"Network error: {ex.Message}").CausedBy(ex));
+        }
+    }
+
     private async Task<Result<KnowledgePacket>> CallKnowledgeApiAsync(string endpoint, string text, CancellationToken cancellationToken)
     {
         try