feat: implement dynamic knowledge graph updates and state management services

src/NexusReader.Infrastructure/DependencyInjection.cs

@@ -24,9 +24,11 @@ public static class DependencyInjection
         services.Configure<AiSettings>(configuration.GetSection(AiSettings.SectionName));
         var aiSettings = configuration.GetSection(AiSettings.SectionName).Get<AiSettings>() ?? new AiSettings();
 
+        Console.WriteLine($"[Infrastructure] AI Configured: Model={aiSettings.Model}, KeyPresent={!string.IsNullOrWhiteSpace(aiSettings.ApiKey) && aiSettings.ApiKey != "PLACEHOLDER"}");
+
         if (string.IsNullOrWhiteSpace(aiSettings.ApiKey) || aiSettings.ApiKey == "PLACEHOLDER")
         {
-            // We don't throw here to allow the app to start, but services using AI will fail gracefully
+            Console.WriteLine("[Infrastructure] WARNING: AI API Key is missing or placeholder!");
         }
 
         services.AddResiliencePipeline("ai-retry", builder =>

src/NexusReader.Infrastructure/Services/KnowledgeService.cs

@@ -41,12 +41,15 @@ public class KnowledgeService : IKnowledgeService
             return Result.Fail("Input text is empty.");
         }
 
+        Console.WriteLine($"[KnowledgeService] Starting extraction for text: {text.Substring(0, Math.Min(text.Length, 50))}...");
+
         // Normalize text to ensure consistent hashing and reduce token noise
         var normalizedText = ContentHasher.Normalize(text);
 
         // Phase 4: Request Pre-processing (Token Saving)
         if (normalizedText.Length > _settings.MaxInputLength)
         {
+            Console.WriteLine($"[KnowledgeService] Error: Input too long ({normalizedText.Length} > {_settings.MaxInputLength})");
             return Result.Fail($"Input text is too long ({normalizedText.Length} characters after normalization). Max allowed is {_settings.MaxInputLength}.");
         }
 
@@ -62,6 +65,7 @@ public class KnowledgeService : IKnowledgeService
 
         if (cached != null)
         {
+            Console.WriteLine($"[KnowledgeService] Cache hit for hash: {hash}");
             try
             {
                 var packet = JsonSerializer.Deserialize<KnowledgePacket>(cached.JsonData);
@@ -70,18 +74,19 @@ public class KnowledgeService : IKnowledgeService
                     return Result.Ok(packet);
                 }
             }
-            catch (JsonException)
+            catch (JsonException ex)
             {
-                // If deserialization fails, we proceed to call the AI
+                Console.WriteLine($"[KnowledgeService] Cache deserialization error: {ex.Message}");
             }
         }
 
         // 2. Call AI Client
         try
         {
+            Console.WriteLine($"[KnowledgeService] Calling Gemini AI with Model: {_settings.Model}...");
             var options = new ChatOptions
             {
-                ResponseFormat = ChatResponseFormat.Json,
+                // ResponseFormat = ChatResponseFormat.Json, // Disabled due to GeminiMappingException in current library version
                 Temperature = (float)_settings.Temperature,
                 MaxOutputTokens = _settings.MaxOutputTokens
             };
@@ -96,19 +101,24 @@ public class KnowledgeService : IKnowledgeService
             var jsonResponse = response.Text;
             if (string.IsNullOrWhiteSpace(jsonResponse))
             {
+                Console.WriteLine("[KnowledgeService] AI returned empty response.");
                 return Result.Fail("AI returned an empty response.");
             }
 
+            Console.WriteLine($"[KnowledgeService] AI Response received ({jsonResponse.Length} chars).");
+
             // Cleanup potential markdown if Gemini still adds it despite options
             jsonResponse = jsonResponse.Replace("```json", "").Replace("```", "").Trim();
 
             var knowledgePacket = JsonSerializer.Deserialize<KnowledgePacket>(jsonResponse);
             if (knowledgePacket == null)
             {
+                Console.WriteLine("[KnowledgeService] Failed to deserialize JSON response.");
                 return Result.Fail("Failed to deserialize AI response.");
             }
 
             // 3. Save to Cache
+            Console.WriteLine("[KnowledgeService] Saving result to cache...");
             var cacheEntry = new SemanticKnowledgeCache
             {
                 ContentHash = hash,
@@ -118,7 +128,6 @@ public class KnowledgeService : IKnowledgeService
                 CreatedAt = DateTime.UtcNow
             };
 
-            // Handle potential race condition if multiple requests for same text arrive
             if (cached == null)
             {
                 _dbContext.SemanticKnowledgeCache.Add(cacheEntry);
@@ -130,12 +139,34 @@ public class KnowledgeService : IKnowledgeService
             }
 
             await _dbContext.SaveChangesAsync(cancellationToken);
+            Console.WriteLine("[KnowledgeService] Extraction successful.");
 
             return Result.Ok(knowledgePacket);
         }
         catch (Exception ex)
         {
+            Console.WriteLine($"[KnowledgeService] CRITICAL ERROR: {ex.GetType().Name}: {ex.Message}");
+            if (ex.InnerException != null)
+                Console.WriteLine($"[KnowledgeService] Inner Error: {ex.InnerException.Message}");
+            
             return Result.Fail(new Error("Failed to extract knowledge from AI").CausedBy(ex));
         }
     }
+
+    public async Task<Result> ClearCacheAsync(CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            Console.WriteLine("[KnowledgeService] Clearing SemanticKnowledgeCache...");
+            _dbContext.SemanticKnowledgeCache.RemoveRange(_dbContext.SemanticKnowledgeCache);
+            await _dbContext.SaveChangesAsync(cancellationToken);
+            Console.WriteLine("[KnowledgeService] Cache cleared successfully.");
+            return Result.Ok();
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"[KnowledgeService] Error clearing cache: {ex.Message}");
+            return Result.Fail($"Failed to clear cache: {ex.Message}");
+        }
+    }
 }

src/NexusReader.Infrastructure/Services/PromptRegistry.cs

@@ -3,7 +3,11 @@ namespace NexusReader.Infrastructure.Services;
 public static class PromptRegistry
 {
     public const string KnowledgeExtractionSystemPrompt = 
-        "You are an expert educator. Analyze the provided text to extract key concepts and generate relevant quizzes. " +
+        "You are an expert educator. Analyze the provided text to extract key concepts, generate relevant quizzes, and construct a knowledge graph. " +
         "CRITICAL: Return ONLY a minified JSON object. Do NOT include markdown formatting like ```json or ```. Do NOT include explanations. " +
-        "Schema: { \"concepts\": [ { \"title\": \"string\", \"description\": \"string\" } ], \"quizzes\": [ { \"question\": \"string\", \"options\": [ \"string\" ], \"correct_index\": 0 } ] }.";
+        "Schema: { " +
+        "\"concepts\": [ { \"title\": \"string\", \"description\": \"string\" } ], " +
+        "\"quizzes\": [ { \"question\": \"string\", \"options\": [ \"string\" ], \"correct_index\": 0 } ], " +
+        "\"graph\": { \"nodes\": [ { \"id\": \"string\", \"label\": \"string\", \"group\": \"concept\" } ], \"links\": [ { \"source\": \"string\", \"target\": \"string\", \"value\": 1 } ] } " +
+        "}.";
 }