Merge feature/fix-mistral-story-generation into main

.env.example

@@ -16,7 +16,7 @@ JWT_EXPIREHOURS=24
 # ============================================
 MISTRAL_APIKEY=YOUR_MISTRAL_API_KEY_HERE
 MISTRAL_BASEURL=https://api.mistral.ai/v1/
-MISTRAL_DEFAULTMODEL=mistral-medium
+MISTRAL_DEFAULTMODEL=mistral-small-latest
 MISTRAL_TIMEOUTSECONDS=30
 MISTRAL_MAXRETRIES=3
 MISTRAL_RATELIMITPERMINUTE=10

GermanApp/Application/Models/MistralRequest.cs

@@ -1,3 +1,5 @@
+using System.Text.Json.Serialization;
+
 namespace GermanApp.Application.Models;
 
 /// <summary>
@@ -108,72 +110,38 @@ public record MistralChatRequest
     /// <summary>
     /// ID of the model to use.
     /// </summary>
-    public string Model { get; init; } = "mistral-medium";
+    [JsonPropertyName("model")]
+    public string Model { get; init; } = "mistral-small-latest";
 
     /// <summary>
     /// A list of messages comprising the conversation so far.
     /// </summary>
+    [JsonPropertyName("messages")]
     public IReadOnlyList<MistralMessage> Messages { get; init; } = new List<MistralMessage>();
 
     /// <summary>
     /// The maximum number of tokens to generate in the completion.
     /// </summary>
-    public int? MaxTokens { get; init; } = 512;
+    [JsonPropertyName("max_tokens")]
+    public int? MaxTokens { get; init; }
 
     /// <summary>
     /// What sampling temperature to use.
     /// </summary>
-    public double? Temperature { get; init; } = 0.7;
+    [JsonPropertyName("temperature")]
-
+    public double? Temperature { get; init; }
-    /// <summary>
-    /// Nucleus sampling.
-    /// </summary>
-    public double? TopP { get; init; } = 1.0;
-
-    /// <summary>
-    /// How many chat completions to generate for each input message.
-    /// </summary>
-    public int? N { get; init; } = 1;
-
-    /// <summary>
-    /// Whether to stream partial responses.
-    /// </summary>
-    public bool? Stream { get; init; } = false;
-
-    /// <summary>
-    /// Up to 4 sequences where the API will stop generating further tokens.
-    /// </summary>
-    public IReadOnlyList<string>? Stop { get; init; }
-
-    /// <summary>
-    /// Number between -2.0 and 2.0. Positive values penalize new tokens based on their frequency.
-    /// </summary>
-    public double? FrequencyPenalty { get; init; }
-
-    /// <summary>
-    /// Number between -2.0 and 2.0. Positive values penalize new tokens based on whether they appear.
-    /// </summary>
-    public double? PresencePenalty { get; init; }
-
-    /// <summary>
-    /// User identifier for tracking usage.
-    /// </summary>
-    public string? User { get; init; }
 
     /// <summary>
     /// Factory method to create a chat request.
     /// </summary>
-    public static MistralChatRequest CreateChat(IReadOnlyList<MistralMessage> messages, string model = "mistral-medium", int maxTokens = 512)
+    public static MistralChatRequest CreateChat(IReadOnlyList<MistralMessage> messages, string model = "mistral-small-latest", int maxTokens = 512)
     {
         return new MistralChatRequest
         {
             Model = model,
             Messages = messages,
             MaxTokens = maxTokens,
-            Temperature = 0.7,
+            Temperature = 0.7
-            TopP = 1.0,
-            N = 1,
-            Stream = false
         };
     }
 }
@@ -186,11 +154,13 @@ public record MistralMessage
     /// <summary>
     /// The role of the message author.
     /// </summary>
+    [JsonPropertyName("role")]
     public string Role { get; init; } = string.Empty;
 
     /// <summary>
     /// The content of the message.
     /// </summary>
+    [JsonPropertyName("content")]
     public string Content { get; init; } = string.Empty;
 
     /// <summary>

GermanApp/Application/Services/MistralService.cs

@@ -24,6 +24,7 @@ public class MistralService : IMistralService
 
     /// <summary>
     /// Generates text from a prompt using Mistral API.
+    /// Uses chat completion endpoint (completions endpoint is deprecated).
     /// </summary>
     public virtual async Task<string> GenerateTextAsync(
         string prompt,
@@ -33,22 +34,29 @@ public class MistralService : IMistralService
         CancellationToken cancellationToken = default)
     {
         model ??= _config.DefaultModel;
-        maxTokens ??= 500;
 
-        var request = new MistralRequest
+        // Use chat completion endpoint instead of completions (which is deprecated)
+        // Send minimal request matching the working curl: only model + messages
+        var messages = new List<MistralMessage>
         {
-            Model = model,
+            new MistralMessage { Role = "user", Content = prompt }
-            Prompt = prompt,
-            Temperature = temperature,
-            MaxTokens = maxTokens.Value
         };
 
-        var response = await _connector.CompleteAsync(request, cancellationToken);
+        // Build request - only include max_tokens and temperature if explicitly provided
+        var request = new MistralChatRequest
+        {
+            Model = model,
+            Messages = messages,
+            MaxTokens = maxTokens,
+            Temperature = temperature == 0.7f ? null : temperature
+        };
+
+        var response = await _connector.ChatAsync(request, cancellationToken);
         
         if (response.Choices == null || response.Choices.Count == 0)
             throw new InvalidOperationException("No choices returned from Mistral API");
 
-        return response.Choices[0].Text ?? string.Empty;
+        return response.Choices[0].Message?.Content ?? string.Empty;
     }
 
     /// <summary>

GermanApp/Application/Services/StoryGenerationService.cs

@@ -52,6 +52,8 @@ public class StoryGenerationService
         int levelId,
         string theme,
         IReadOnlyList<Lesson> lessons,
+        int segmentCount = 5,
+        string? customPrompt = null,
         CancellationToken cancellationToken = default)
     {
         _logger.LogInformation(
@@ -68,7 +70,7 @@ public class StoryGenerationService
         }
 
         // Build the prompt for Mistral
-        var prompt = BuildStoryPrompt(levelId, theme, allVocabulary, lessons.Count);
+        var prompt = BuildStoryPrompt(levelId, theme, allVocabulary, segmentCount, customPrompt);
         
         _logger.LogDebug("Story generation prompt: {Prompt}", prompt);
 
@@ -347,7 +349,7 @@ public class StoryGenerationService
     /// <param name="vocabulary">List of vocabulary words</param>
     /// <param name="segmentCount">Number of segments to generate</param>
     /// <returns>The prompt string</returns>
-    private string BuildStoryPrompt(int levelId, string theme, IReadOnlyList<string> vocabulary, int segmentCount)
+    private string BuildStoryPrompt(int levelId, string theme, IReadOnlyList<string> vocabulary, int segmentCount, string? customPrompt = null)
     {
         var levelCode = GetLevelCode(levelId);
         var vocabularyString = string.Join(", ", vocabulary.Take(20));
@@ -358,12 +360,19 @@ public class StoryGenerationService
         }
 
         var requirements = GetStoryRequirements(levelCode);
-        return $@"Write a {segmentCount}-part continuous story for a German {levelCode} learner. 
+        var prompt = $@"Write a {segmentCount}-part continuous story for a German {levelCode} learner. 
 The story theme is: {theme}. 
 Include these German words and phrases: {vocabularyString}. 
 
 REQUIREMENTS:
 {requirements}";
+        
+        if (!string.IsNullOrWhiteSpace(customPrompt))
+        {
+            prompt += $"\n\nCUSTOM PROMPT:\n{customPrompt}";
+        }
+        
+        return prompt;
     }
 
     private string GetStoryRequirements(string levelCode) => levelCode switch

GermanApp/Infrastructure/Configuration/MistralConfig.cs

@@ -19,9 +19,9 @@ public class MistralConfig
 
     /// <summary>
     /// The default model to use for completions.
-    /// Default: mistral-medium
+    /// Default: mistral-small-latest
     /// </summary>
-    public string DefaultModel { get; set; } = "mistral-medium";
+    public string DefaultModel { get; set; } = "mistral-small-latest";
 
     /// <summary>
     /// Timeout in seconds for HTTP requests.

GermanApp/Infrastructure/Services/MistralConnector.cs

@@ -32,10 +32,11 @@ public class MistralConnector : IMistralConnector
         _cache = cache;
         
         // Initialize JSON options (always needed)
+        // Mistral API uses snake_case for property names (max_tokens, not maxTokens)
         _jsonOptions = new JsonSerializerOptions
         {
             PropertyNameCaseInsensitive = true,
-            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+            PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
         };
         
         // Skip validation and initialization during EF migrations
@@ -160,6 +161,7 @@ public class MistralConnector : IMistralConnector
             var response = await ExecuteWithRetryAsync(async () =>
             {
                 var json = JsonSerializer.Serialize(request, _jsonOptions);
+                _logger.LogDebug("Mistral API request to {Endpoint}: {Request}", endpoint, json);
                 var content = new StringContent(json, Encoding.UTF8, "application/json");
                 var httpResponse = await _httpClient.PostAsync(endpoint, content, cancellationToken);
                 return await HandleResponseAsync<TResponse>(httpResponse);
@@ -224,22 +226,68 @@ public class MistralConnector : IMistralConnector
         if (!httpResponse.IsSuccessStatusCode)
         {
             var errorContent = await httpResponse.Content.ReadAsStringAsync();
-            var errorResponse = JsonSerializer.Deserialize<MistralErrorResponse>(errorContent, _jsonOptions);
+            _logger.LogError("Mistral API error response (status {StatusCode}): {Content}",
+                (int)httpResponse.StatusCode, errorContent);
             
-            var errorCode = errorResponse?.ErrorCode ?? MapStatusCodeToErrorCode(httpResponse.StatusCode);
+            AiErrorCode errorCode = MapStatusCodeToErrorCode(httpResponse.StatusCode);
-            var message = errorResponse?.Message ?? $"HTTP {(int)httpResponse.StatusCode}: {httpResponse.ReasonPhrase}";
+            string message = $"HTTP {(int)httpResponse.StatusCode}: {httpResponse.ReasonPhrase}";
+            
+            // Try to extract error message from JSON without requiring exact DTO match
+            try
+            {
+                using var doc = JsonDocument.Parse(errorContent);
+                if (doc.RootElement.TryGetProperty("message", out var messageElement))
+                {
+                    message = messageElement.ValueKind switch
+                    {
+                        JsonValueKind.String => messageElement.GetString() ?? message,
+                        JsonValueKind.Object => messageElement.EnumerateObject().FirstOrDefault().Value.GetString() ?? message,
+                        JsonValueKind.Array => messageElement.EnumerateArray().FirstOrDefault().GetString() ?? message,
+                        _ => message
+                    };
+                }
+                if (doc.RootElement.TryGetProperty("type", out var typeElement) && typeElement.ValueKind == JsonValueKind.String)
+                {
+                    errorCode = typeElement.GetString() switch
+                    {
+                        "rate_limit_exceeded" or "rate_limit" => AiErrorCode.RateLimited,
+                        "invalid_request_error" => AiErrorCode.InvalidRequest,
+                        "authentication_error" or "invalid_api_key" => AiErrorCode.AuthenticationError,
+                        "server_error" or "internal_server_error" => AiErrorCode.Temporary,
+                        "timeout" => AiErrorCode.Timeout,
+                        _ => errorCode
+                    };
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Could not parse error response JSON, using status code mapping");
+            }
             
             _logger.LogError("Mistral API error: {StatusCode} - {Message}", 
                 (int)httpResponse.StatusCode, message);
             
-            httpResponse.EnsureSuccessStatusCode(); // This will throw
+            httpResponse.EnsureSuccessStatusCode();
         }
 
         var content = await httpResponse.Content.ReadAsStringAsync();
-        return JsonSerializer.Deserialize<T>(content, _jsonOptions) 
+        try
-            ?? throw new AiServiceException("Invalid response from Mistral API",
+        {
+            var result = JsonSerializer.Deserialize<T>(content, _jsonOptions);
+            if (result == null)
+            {
+                _logger.LogError("Mistral API returned null when deserializing to {Type}. Content: {Content}", typeof(T).Name, content);
+                throw new AiServiceException("Invalid response from Mistral API",
                     AiErrorCode.InvalidResponse);
             }
+            return result;
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to deserialize Mistral response to {Type}. Raw JSON: {Content}", typeof(T).Name, content);
+            throw;
+        }
+    }
 
     private string GenerateCacheKey<T>(T request)
     {

GermanApp/Presentation/Controllers/StoryController.cs

@@ -243,6 +243,8 @@ public class StoryController : ControllerBase
                 levelId,
                 request.Theme,
                 lessons,
+                request.SegmentCount,
+                request.CustomPrompt,
                 cancellationToken);
 
             return Ok(response);

docker-compose.yml

@@ -34,17 +34,17 @@ services:
       Jwt__Issuer: ${JWT_ISSUER:-DeutschLernen}
       Jwt__Audience: ${JWT_AUDIENCE:-DeutschLernen}
       Jwt__ExpireHours: ${JWT_EXPIREHOURS:-24}
-      # Mistral API Configuration (from appsettings.Development.json)
+      # Mistral API Configuration (from Woodpecker secrets or environment)
-      Mistral__ApiKey: Odq70O3NUQ1H8hMhGJAFAz5OJfukX6lT
+      Mistral__ApiKey: ${MISTRAL_APIKEY:-}
-      Mistral__BaseUrl: https://api.mistral.ai/v1/
+      Mistral__BaseUrl: ${MISTRAL_BASEURL:-https://api.mistral.ai/v1/}
-      Mistral__DefaultModel: mistral-medium
+      Mistral__DefaultModel: ${MISTRAL_DEFAULTMODEL:-mistral-small-latest}
-      Mistral__TimeoutSeconds: 30
+      Mistral__TimeoutSeconds: ${MISTRAL_TIMEOUTSECONDS:-30}
-      Mistral__MaxRetries: 3
+      Mistral__MaxRetries: ${MISTRAL_MAXRETRIES:-3}
-      Mistral__RateLimitPerMinute: 10
+      Mistral__RateLimitPerMinute: ${MISTRAL_RATELIMITPERMINUTE:-10}
-      Mistral__EnableCaching: true
+      Mistral__EnableCaching: ${MISTRAL_ENABLECACHING:-true}
-      Mistral__CacheTTLMinutes: 60
+      Mistral__CacheTTLMinutes: ${MISTRAL_CACHETTLMINUTES:-60}
-      Mistral__CircuitBreakerFailureThreshold: 5
+      Mistral__CircuitBreakerFailureThreshold: ${MISTRAL_CIRCUITBREAKERFAILURETHRESHOLD:-5}
-      Mistral__CircuitBreakerResetMinutes: 1
+      Mistral__CircuitBreakerResetMinutes: ${MISTRAL_CIRCUITBREAKERRESETMINUTES:-1}
     depends_on:
       db:
         condition: service_healthy