Merge feature/inbox-2: POST /api/requests/{id}/draft (AI German reply draft, never auto-send), extract OpenAiChatClient to Ai/, privacy stripping, 8 tests [god-QA pending]

GerbilManager.Tests/ApiFactory.cs

@@ -19,6 +19,13 @@ public sealed class ApiFactory : WebApplicationFactory<Program>
 {
     private readonly SqliteConnection _connection = new("DataSource=:memory:");
 
+    /// <summary>
+    /// INBOX-2: Test-spezifische DI-Überschreibungen (z. B. AI-Stub-Handler).
+    /// Init-Property statt Konstruktor — xUnit-Klassen-Fixtures erlauben nur
+    /// EINEN öffentlichen (parameterlosen) Konstruktor.
+    /// </summary>
+    public Action<IServiceCollection>? ConfigureTestServices { get; init; }
+
     public string ContractRoot { get; } =
         Path.Combine(Path.GetTempPath(), $"gerbil-contract-tests-{Guid.NewGuid():N}");
 
@@ -46,6 +53,8 @@ public sealed class ApiFactory : WebApplicationFactory<Program>
             using var provider = services.BuildServiceProvider();
             using var scope = provider.CreateScope();
             scope.ServiceProvider.GetRequiredService<ApplicationContext>().Database.EnsureCreated();
+
+            ConfigureTestServices?.Invoke(services);
         });
     }
 

GerbilManager.Tests/InboxDraftTests.cs

@@ -0,0 +1,217 @@
+using System.Net;
+using System.Net.Http.Json;
+using System.Text;
+using System.Text.Json;
+using GerbilManagerWebAPI.Inbox;
+using GerbilManagerWebAPI.Models;
+using GerbilManagerWebAPI.SaleAd;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+
+namespace GerbilManager.Tests
+{
+    /// <summary>
+    /// INBOX-2: KI-Antwortentwurf — Prompt-Assembly (inkl. Datenminimierung +
+    /// Zitat-/Signatur-Stripping), 503-unkonfiguriert, und der Endpoint-Round-Trip
+    /// gegen einen Stub-Anbieter (Entwurf wird gespeichert UND zurückgegeben).
+    /// </summary>
+    public class InboxDraftTests
+    {
+        private static Request SampleRequest() => new()
+        {
+            Id = Guid.NewGuid(),
+            GmailMessageId = $"<{Guid.NewGuid():N}@mail.example>",
+            FromAddress = "anna.musterfrau@example.de",
+            FromName = "Anna Musterfrau",
+            Subject = "Anfrage: zwei Weibchen?",
+            BodyText = "Hallo! Habt ihr aktuell zwei junge Weibchen zur Abgabe?\nViele Grüße, Anna",
+            ReceivedAt = DateTimeOffset.UtcNow,
+        };
+
+        // ── Zitat-/Signatur-Stripping ──────────────────────────────────────
+
+        [Fact]
+        public void StripQuotedText_entfernt_Zitate_Signatur_und_Outlook_Header()
+        {
+            var body = string.Join('\n',
+                "Hallo, habt ihr Tiere abzugeben?",
+                "> alte zitierte Zeile",
+                "Von: jemand@example.de",
+                "Danke!",
+                "-- ",
+                "Anna Musterfrau",
+                "Musterweg 1");
+            var stripped = DraftReplyService.StripQuotedText(body);
+
+            Assert.Contains("Hallo, habt ihr Tiere abzugeben?", stripped);
+            Assert.Contains("Danke!", stripped);
+            Assert.DoesNotContain("alte zitierte Zeile", stripped);
+            Assert.DoesNotContain("jemand@example.de", stripped);
+            Assert.DoesNotContain("Musterweg 1", stripped); // Signatur weg
+        }
+
+        [Fact]
+        public void StripQuotedText_schneidet_beim_Gmail_Zitat_Intro_ab()
+        {
+            var body = "Meine Frage steht oben.\nAm 05.06.2026 um 10:00 schrieb Zucht der kleinen Chaoten:\n> früherer Verlauf";
+            var stripped = DraftReplyService.StripQuotedText(body);
+
+            Assert.Equal("Meine Frage steht oben.", stripped);
+        }
+
+        // ── Prompt-Assembly + Datenminimierung ─────────────────────────────
+
+        [Fact]
+        public void UserPrompt_enthält_Anfrage_und_Abgabeliste_aber_keine_Mailadresse()
+        {
+            var prompt = DraftReplyService.BuildUserPrompt(SampleRequest(),
+                [new DraftReplyService.ForSaleAnimal("Frieda", "Gold"),
+                 new DraftReplyService.ForSaleAnimal("Fine", null)]);
+
+            Assert.Contains("Von: Anna Musterfrau", prompt);
+            Assert.Contains("Betreff: Anfrage: zwei Weibchen?", prompt);
+            Assert.Contains("zwei junge Weibchen zur Abgabe", prompt);
+            Assert.Contains("- Frieda (Gold)", prompt);
+            Assert.Contains("- Fine", prompt);
+            // Datenminimierung: die E-Mail-Adresse der Absenderin geht NICHT zum Anbieter
+            Assert.DoesNotContain("anna.musterfrau@example.de", prompt);
+        }
+
+        [Fact]
+        public void UserPrompt_ohne_Abgabetiere_enthält_keine_Liste()
+        {
+            var prompt = DraftReplyService.BuildUserPrompt(SampleRequest(), []);
+            Assert.DoesNotContain("abzugebende Tiere", prompt);
+        }
+
+        [Fact]
+        public void SystemPrompt_verlangt_Entwurf_ohne_Preise_und_ohne_erfundene_Fakten()
+        {
+            var prompt = DraftReplyService.BuildSystemPrompt();
+            Assert.Contains("ENTWERFEN", prompt);
+            Assert.Contains("KEINE Fakten erfinden", prompt);
+            Assert.Contains("Keine Preise", prompt);
+            Assert.Contains("keine Adressen", prompt);
+        }
+
+        // ── 503: unkonfiguriert (Service-Ebene) ────────────────────────────
+
+        [Fact]
+        public async Task DraftAsync_meldet_NotConfigured_ohne_AI_Konfiguration()
+        {
+            var service = new DraftReplyService(
+                new HttpClient(new StubHandler(_ => throw new InvalidOperationException("darf nicht aufgerufen werden"))),
+                Options.Create(new AiOptions()));
+
+            var result = await service.DraftAsync(SampleRequest(), []);
+
+            Assert.Equal(GerbilManagerWebAPI.Ai.AiCallStatus.NotConfigured, result.Status);
+        }
+
+        // ── Endpoint-Round-Trip ────────────────────────────────────────────
+
+        [Fact]
+        public async Task Draft_Endpoint_meldet_503_AiKeyMissing_wenn_unkonfiguriert()
+        {
+            using var factory = new ApiFactory();
+            var id = await SeedRequestAsync(factory);
+
+            var response = await factory.CreateClient().PostAsync($"/api/requests/{id}/draft", null);
+
+            Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+            Assert.Contains("AiKeyMissing", await response.Content.ReadAsStringAsync());
+        }
+
+        [Fact]
+        public async Task Draft_Endpoint_speichert_und_liefert_den_Entwurf_des_Stubs()
+        {
+            const string canned = "Hallo Anna,\n\nschön, dass du fragst — aktuell suchen Frieda und Fine ein Zuhause.\n\nHerzliche Grüße";
+            var stub = new StubHandler(_ => Canned(canned));
+            using var factory = new ApiFactory
+            {
+                ConfigureTestServices = services =>
+                {
+                    services.PostConfigure<AiOptions>(o =>
+                    {
+                        o.BaseUrl = "https://api.example.com/v1";
+                        o.ApiKey = "test";
+                        o.Model = "test-model";
+                    });
+                    services.AddHttpClient<DraftReplyService>()
+                        .ConfigurePrimaryHttpMessageHandler(() => stub);
+                },
+            };
+
+            var id = await SeedRequestAsync(factory, alsoForSaleGerbil: true);
+            var client = factory.CreateClient();
+
+            var response = await client.PostAsync($"/api/requests/{id}/draft", null);
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+            using var dto = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
+            Assert.Equal(canned, dto.RootElement.GetProperty("draftReply").GetString());
+
+            // Persistiert: erneutes GET liefert den Entwurf
+            var again = await client.GetFromJsonAsync<JsonElement>($"/api/requests/{id}");
+            Assert.Equal(canned, again.GetProperty("draftReply").GetString());
+
+            // Wire-Privacy: Anfragetext + ForSale-Tier gingen zum Anbieter, die
+            // Mailadresse der Absenderin NICHT.
+            Assert.NotNull(stub.LastRequestBody);
+            Assert.Contains("zwei junge Weibchen", stub.LastRequestBody);
+            Assert.Contains("Aki", stub.LastRequestBody);
+            Assert.DoesNotContain("anna.musterfrau@example.de", stub.LastRequestBody);
+        }
+
+        // ── Helfer ─────────────────────────────────────────────────────────
+
+        private static async Task<Guid> SeedRequestAsync(ApiFactory factory, bool alsoForSaleGerbil = false)
+        {
+            using var scope = factory.Services.CreateScope();
+            var db = scope.ServiceProvider.GetRequiredService<ApplicationContext>();
+            var request = SampleRequest();
+            db.Add(request);
+            if (alsoForSaleGerbil)
+            {
+                db.Add(new Gerbil
+                {
+                    Id = Guid.NewGuid(),
+                    Name = "Aki",
+                    Gender = Gender.female,
+                    Status = GerbilStatus.ForSale,
+                });
+            }
+            await db.SaveChangesAsync();
+            return request.Id;
+        }
+
+        private static HttpResponseMessage Canned(string content)
+        {
+            var completion = new
+            {
+                choices = new[] { new { message = new { role = "assistant", content } } },
+            };
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(JsonSerializer.Serialize(completion),
+                    Encoding.UTF8, "application/json"),
+            };
+        }
+
+        /// <summary>HttpMessageHandler-Stub (Variante von SaleAdTests, hier mit Body-Capture).</summary>
+        private sealed class StubHandler(Func<HttpRequestMessage, HttpResponseMessage> respond)
+            : HttpMessageHandler
+        {
+            public string? LastRequestBody { get; private set; }
+
+            protected override async Task<HttpResponseMessage> SendAsync(
+                HttpRequestMessage request, CancellationToken cancellationToken)
+            {
+                LastRequestBody = request.Content is null
+                    ? null
+                    : await request.Content.ReadAsStringAsync(cancellationToken);
+                return respond(request);
+            }
+        }
+    }
+}

GerbilManagerWebAPI/Ai/OpenAiChatClient.cs

@@ -0,0 +1,99 @@
+using System.Net.Http.Headers;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using GerbilManagerWebAPI.SaleAd;
+using Microsoft.Extensions.Options;
+
+namespace GerbilManagerWebAPI.Ai
+{
+    public enum AiCallStatus
+    {
+        Ok,
+        /// <summary>AI section not (fully) configured -> callers map to 503 "AiKeyMissing".</summary>
+        NotConfigured,
+        /// <summary>Provider call failed -> callers map to 502 "AiUpstreamError".</summary>
+        UpstreamError,
+    }
+
+    public sealed record AiCallResult(AiCallStatus Status, string? Text, string? Error = null);
+
+    /// <summary>
+    /// INBOX-2: provider-agnostic chat client, extracted from SaleAdService so the
+    /// reply-draft (and future AI features) reuse the SAME wire implementation:
+    /// plain JSON POST to {AI:BaseUrl}/chat/completions with a Bearer key — covers
+    /// Gemini (compat endpoint), Groq, Mistral, local Ollama; no vendor SDK.
+    /// Configuration stays the single AI section (AiOptions, env-only).
+    /// </summary>
+    public sealed class OpenAiChatClient(HttpClient http, IOptions<AiOptions> options)
+    {
+        private static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
+        };
+
+        public async Task<AiCallResult> CompleteAsync(
+            string systemPrompt, string userPrompt, CancellationToken ct = default)
+        {
+            var ai = options.Value;
+            if (!ai.IsConfigured)
+            {
+                return new AiCallResult(AiCallStatus.NotConfigured, null,
+                    "KI-Anbieter ist nicht konfiguriert (AI__BaseUrl / AI__ApiKey / AI__Model).");
+            }
+
+            var payload = new ChatRequest(
+                Model: ai.Model!,
+                Messages:
+                [
+                    new ChatMessage("system", systemPrompt),
+                    new ChatMessage("user", userPrompt),
+                ],
+                Temperature: 0.7);
+
+            using var httpRequest = new HttpRequestMessage(HttpMethod.Post, BuildCompletionsUri(ai.BaseUrl!))
+            {
+                Content = new StringContent(JsonSerializer.Serialize(payload, JsonOptions),
+                    Encoding.UTF8, "application/json"),
+            };
+            httpRequest.Headers.Authorization = new AuthenticationHeaderValue("Bearer", ai.ApiKey);
+
+            try
+            {
+                using var response = await http.SendAsync(httpRequest, ct);
+                var body = await response.Content.ReadAsStringAsync(ct);
+                if (!response.IsSuccessStatusCode)
+                {
+                    return new AiCallResult(AiCallStatus.UpstreamError, null,
+                        $"KI-Anbieter antwortete mit HTTP {(int)response.StatusCode}.");
+                }
+
+                var completion = JsonSerializer.Deserialize<ChatResponse>(body, JsonOptions);
+                var text = completion?.Choices?.FirstOrDefault()?.Message?.Content?.Trim();
+                return string.IsNullOrWhiteSpace(text)
+                    ? new AiCallResult(AiCallStatus.UpstreamError, null,
+                        "KI-Antwort enthielt keinen Text.")
+                    : new AiCallResult(AiCallStatus.Ok, text);
+            }
+            catch (Exception ex) when (ex is HttpRequestException or TaskCanceledException or JsonException)
+            {
+                return new AiCallResult(AiCallStatus.UpstreamError, null,
+                    $"KI-Anbieter nicht erreichbar: {ex.Message}");
+            }
+        }
+
+        /// <summary>{BaseUrl}/chat/completions — tolerant of a trailing slash on BaseUrl.</summary>
+        internal static Uri BuildCompletionsUri(string baseUrl) =>
+            new($"{baseUrl.TrimEnd('/')}/chat/completions");
+
+        // ── OpenAI-compatible wire records (request + the slice of the response we read) ──
+        internal sealed record ChatRequest(string Model, List<ChatMessage> Messages, double? Temperature);
+
+        internal sealed record ChatMessage(string Role, string Content);
+
+        internal sealed record ChatResponse(List<ChatChoice>? Choices);
+
+        internal sealed record ChatChoice(ChatMessage? Message);
+    }
+}

GerbilManagerWebAPI/Endpoints/RequestEndpoints.cs

@@ -51,6 +51,34 @@ namespace GerbilManagerWebAPI.Endpoints
                 return TypedResults.NoContent();
             });
 
+            // POST /api/requests/{id}/draft — INBOX-2: KI-Antwortentwurf. NUR Entwurf
+            // (human-in-the-loop, Versand ist /send). 503 AiKeyMissing solange die
+            // AI-Sektion unkonfiguriert ist (gleiches UI-Muster wie sale-ad).
+            api.MapPost("/requests/{id:guid}/draft", async Task<IResult> (
+                Guid id, DraftReplyService drafter, ApplicationContext db, CancellationToken ct) =>
+            {
+                var r = await db.Requests.FirstOrDefaultAsync(x => x.Id == id, ct);
+                if (r is null) return TypedResults.NotFound();
+
+                // Datenminimierung: NUR die ForSale-Liste (Name + Farbschlag) geht
+                // zusätzlich zum Anfragetext an den Anbieter (arch §privacy).
+                var forSale = await db.Gerbils.AsNoTracking()
+                    .Where(g => g.Status == GerbilStatus.ForSale)
+                    .OrderBy(g => g.Name)
+                    .Select(g => new DraftReplyService.ForSaleAnimal(g.Name, g.ColorVariety!.Name))
+                    .ToListAsync(ct);
+
+                var result = await drafter.DraftAsync(r, forSale, ct);
+                if (result.Status == Ai.AiCallStatus.NotConfigured)
+                    return Results.Json(new { code = "AiKeyMissing", message = result.Error }, statusCode: 503);
+                if (result.Status != Ai.AiCallStatus.Ok)
+                    return Results.Json(new { code = "AiUpstreamError", message = result.Error }, statusCode: 502);
+
+                r.DraftReply = result.Text;
+                await db.SaveChangesAsync(ct);
+                return TypedResults.Ok(ToDto(r));
+            });
+
             // POST /api/requests/{id}/send — send the (edited) reply, threaded, mark Answered
             api.MapPost("/requests/{id:guid}/send", async Task<Results<Ok<RequestDto>, NotFound, ProblemHttpResult>> (
                 Guid id, SendReplyInput input, SendReplyService sender, ApplicationContext db) =>

GerbilManagerWebAPI/Inbox/DraftReplyService.cs

@@ -0,0 +1,108 @@
+using System.Text;
+using System.Text.RegularExpressions;
+using GerbilManagerWebAPI.Ai;
+using GerbilManagerWebAPI.Models;
+using GerbilManagerWebAPI.SaleAd;
+using Microsoft.Extensions.Options;
+
+namespace GerbilManagerWebAPI.Inbox
+{
+    /// <summary>
+    /// INBOX-2: AI reply DRAFT for an incoming inquiry (human-in-the-loop — the
+    /// breeder edits and sends herself, NEVER auto-send; send is INBOX-3).
+    ///
+    /// PRIVACY / data minimization (INBOX-architecture.md §privacy): the prompt
+    /// carries ONLY the inquiry's own text (signatures/quoted history stripped),
+    /// the sender's display name for the greeting, a short German context, and
+    /// optionally the current ForSale animals (name + Farbschlag). NOT the
+    /// contact DB, NOT other requests, NOT any addresses.
+    /// </summary>
+    public sealed class DraftReplyService(HttpClient http, IOptions<AiOptions> options)
+    {
+        private readonly OpenAiChatClient _client = new(http, options);
+
+        public sealed record ForSaleAnimal(string Name, string? Farbschlag);
+
+        public Task<AiCallResult> DraftAsync(
+            Request request, IReadOnlyList<ForSaleAnimal> forSale, CancellationToken ct = default)
+            => _client.CompleteAsync(BuildSystemPrompt(), BuildUserPrompt(request, forSale), ct);
+
+        internal static string BuildSystemPrompt() => """
+            Du hilfst einer Hobby-Rennmaus-Züchterin („Zucht der kleinen Chaoten“), eine
+            freundliche deutsche Antwort auf eine Anfrage zu ENTWERFEN. Sie liest den
+            Entwurf, passt ihn an und versendet selbst.
+
+            Regeln:
+            - Ton: warm, persönlich, hilfsbereit — wie eine erfahrene Hobby-Züchterin,
+              nicht wie ein Unternehmen. Anrede per „du“, Gruß mit dem Namen der
+              anfragenden Person, falls bekannt.
+            - KEINE Fakten erfinden: Verfügbarkeit, Tiere und Eigenschaften NUR aus den
+              mitgelieferten Daten. Ist keine Abgabetier-Liste mitgeliefert oder passt
+              nichts, verweise freundlich darauf, dass sie aktuelle Infos persönlich gibt.
+            - Keine Preise/Schutzgebühren nennen und keine Adressen oder sonstige
+              persönliche Daten — solche Details klärt sie selbst im Gespräch.
+            - Gib NUR den Antworttext aus (ohne Betreff, ohne Erklärungen) und beende
+              mit einem herzlichen Gruß ohne Namens-Signatur.
+            """;
+
+        internal static string BuildUserPrompt(Request request, IReadOnlyList<ForSaleAnimal> forSale)
+        {
+            var sb = new StringBuilder();
+            sb.AppendLine("Entwirf eine Antwort auf folgende Anfrage:");
+            sb.AppendLine();
+            if (!string.IsNullOrWhiteSpace(request.FromName))
+                sb.AppendLine($"Von: {request.FromName}");
+            if (!string.IsNullOrWhiteSpace(request.Subject))
+                sb.AppendLine($"Betreff: {request.Subject}");
+            sb.AppendLine();
+            sb.AppendLine("Anfrage-Text:");
+            sb.AppendLine(StripQuotedText(request.BodyText ?? ""));
+            if (forSale.Count > 0)
+            {
+                sb.AppendLine();
+                sb.AppendLine("Aktuell abzugebende Tiere (einzige zulässige Quelle für Verfügbarkeits-Aussagen):");
+                foreach (var a in forSale)
+                {
+                    sb.AppendLine(string.IsNullOrWhiteSpace(a.Farbschlag)
+                        ? $"- {a.Name}"
+                        : $"- {a.Name} ({a.Farbschlag})");
+                }
+            }
+            return sb.ToString();
+        }
+
+        // ── Signatur-/Zitat-Stripping (best effort, bewusst konservativ) ────
+
+        private static readonly Regex QuoteIntro = new(
+            @"^Am .+ schrieb .+:\s*$", RegexOptions.Compiled);
+
+        private static readonly Regex OutlookHeader = new(
+            @"^(Von|Gesendet|An|Betreff):\s", RegexOptions.Compiled);
+
+        /// <summary>
+        /// Drops quoted history ('&gt;'-lines, the German Gmail "Am … schrieb …:"
+        /// intro, Outlook-style forwarded headers) and everything below a signature
+        /// delimiter ("-- "). Keeps the sender's own words untouched.
+        /// </summary>
+        internal static string StripQuotedText(string body)
+        {
+            var lines = body.Replace("\r\n", "\n").Split('\n');
+            var kept = new List<string>();
+            foreach (var line in lines)
+            {
+                var trimmed = line.TrimEnd();
+                if (trimmed == "--" || trimmed == "-- ")
+                    break; // signature delimiter: everything below is signature
+                if (QuoteIntro.IsMatch(trimmed))
+                    break; // quoted history follows
+                if (trimmed.StartsWith('>'))
+                    continue;
+                if (OutlookHeader.IsMatch(trimmed))
+                    continue;
+                kept.Add(line);
+            }
+            // collapse the whitespace the stripping may have left behind
+            return string.Join("\n", kept).Trim();
+        }
+    }
+}

GerbilManagerWebAPI/Program.cs

@@ -41,6 +41,9 @@ builder.Services.AddOptions<GerbilManagerWebAPI.SaleAd.AiOptions>()
     .BindConfiguration(GerbilManagerWebAPI.SaleAd.AiOptions.SectionName);
 builder.Services.AddHttpClient<GerbilManagerWebAPI.SaleAd.SaleAdService>(
     http => http.Timeout = TimeSpan.FromSeconds(60));
+// INBOX-2: KI-Antwortentwurf (gleiche AI-Sektion, gleicher Wire-Client).
+builder.Services.AddHttpClient<GerbilManagerWebAPI.Inbox.DraftReplyService>(
+    http => http.Timeout = TimeSpan.FromSeconds(60));
 
 // INBOX-0: Gmail inbox. App Password encrypted at rest via Data Protection.
 builder.Services.AddDataProtection();

GerbilManagerWebAPI/SaleAd/SaleAdService.cs

@@ -1,87 +1,35 @@
-using System.Net.Http.Headers;
+using GerbilManagerWebAPI.Ai;
-using System.Text;
-using System.Text.Json;
-using System.Text.Json.Serialization;
 using Microsoft.Extensions.Options;
 
 namespace GerbilManagerWebAPI.SaleAd
 {
     /// <summary>
-    /// FEAT-12a: provider-agnostic AI client for sale-ad generation.
+    /// FEAT-12a: sale-ad generation. The provider-agnostic wire handling lives in
-    ///
+    /// <see cref="OpenAiChatClient"/> (extracted in INBOX-2 so the reply-draft and
-    /// Speaks the OpenAI-compatible chat-completions wire shape — deliberately
+    /// future AI features reuse the SAME implementation); this service contributes
-    /// WITHOUT any vendor SDK: a plain JSON POST to {AI:BaseUrl}/chat/completions
+    /// the sale-ad prompts and the SaleAd-shaped result. Public surface unchanged.
-    /// with a Bearer key covers Google Gemini (compat endpoint), Groq, Mistral,
-    /// local Ollama and any future provider. The wire shape IS the abstraction.
     /// </summary>
     public sealed class SaleAdService(HttpClient http, IOptions<AiOptions> options)
     {
-        private static readonly JsonSerializerOptions JsonOptions = new()
+        private readonly OpenAiChatClient _client = new(http, options);
-        {
-            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
-            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
-        };
 
         public async Task<SaleAdResult> GenerateAsync(SaleAdRequest request, CancellationToken ct = default)
         {
-            var ai = options.Value;
+            var result = await _client.CompleteAsync(
-            if (!ai.IsConfigured)
+                SaleAdPromptBuilder.BuildSystemPrompt(),
+                SaleAdPromptBuilder.BuildUserPrompt(request),
+                ct);
+            var status = result.Status switch
             {
-                return new SaleAdResult(SaleAdStatus.NotConfigured, null,
+                AiCallStatus.Ok => SaleAdStatus.Ok,
-                    "KI-Anbieter ist nicht konfiguriert (AI__BaseUrl / AI__ApiKey / AI__Model).");
+                AiCallStatus.NotConfigured => SaleAdStatus.NotConfigured,
-            }
+                _ => SaleAdStatus.UpstreamError,
-
-            var payload = new ChatRequest(
-                Model: ai.Model!,
-                Messages:
-                [
-                    new ChatMessage("system", SaleAdPromptBuilder.BuildSystemPrompt()),
-                    new ChatMessage("user", SaleAdPromptBuilder.BuildUserPrompt(request)),
-                ],
-                Temperature: 0.7);
-
-            using var httpRequest = new HttpRequestMessage(HttpMethod.Post, BuildCompletionsUri(ai.BaseUrl!))
-            {
-                Content = new StringContent(JsonSerializer.Serialize(payload, JsonOptions),
-                    Encoding.UTF8, "application/json"),
             };
-            httpRequest.Headers.Authorization = new AuthenticationHeaderValue("Bearer", ai.ApiKey);
+            return new SaleAdResult(status, result.Text, result.Error);
-
-            try
-            {
-                using var response = await http.SendAsync(httpRequest, ct);
-                var body = await response.Content.ReadAsStringAsync(ct);
-                if (!response.IsSuccessStatusCode)
-                {
-                    return new SaleAdResult(SaleAdStatus.UpstreamError, null,
-                        $"KI-Anbieter antwortete mit HTTP {(int)response.StatusCode}.");
-                }
-
-                var completion = JsonSerializer.Deserialize<ChatResponse>(body, JsonOptions);
-                var text = completion?.Choices?.FirstOrDefault()?.Message?.Content?.Trim();
-                return string.IsNullOrWhiteSpace(text)
-                    ? new SaleAdResult(SaleAdStatus.UpstreamError, null,
-                        "KI-Antwort enthielt keinen Text.")
-                    : new SaleAdResult(SaleAdStatus.Ok, text);
-            }
-            catch (Exception ex) when (ex is HttpRequestException or TaskCanceledException or JsonException)
-            {
-                return new SaleAdResult(SaleAdStatus.UpstreamError, null,
-                    $"KI-Anbieter nicht erreichbar: {ex.Message}");
-            }
         }
 
-        /// <summary>{BaseUrl}/chat/completions — tolerant of a trailing slash on BaseUrl.</summary>
+        /// <summary>Forwarder kept for the existing config-matrix tests.</summary>
         internal static Uri BuildCompletionsUri(string baseUrl) =>
-            new($"{baseUrl.TrimEnd('/')}/chat/completions");
+            OpenAiChatClient.BuildCompletionsUri(baseUrl);
-
-        // ── OpenAI-compatible wire records (request + the slice of the response we read) ──
-        internal sealed record ChatRequest(string Model, List<ChatMessage> Messages, double? Temperature);
-
-        internal sealed record ChatMessage(string Role, string Content);
-
-        internal sealed record ChatResponse(List<ChatChoice>? Choices);
-
-        internal sealed record ChatChoice(ChatMessage? Message);
     }
 }