diff --git a/GerbilManagerWebAPI/Ai/OpenAiChatClient.cs b/GerbilManagerWebAPI/Ai/OpenAiChatClient.cs
new file mode 100644
index 0000000..4cda969
--- /dev/null
+++ b/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);
+    }
+}
diff --git a/GerbilManagerWebAPI/SaleAd/SaleAdService.cs b/GerbilManagerWebAPI/SaleAd/SaleAdService.cs
index 47a7c5c..109c2a8 100644
--- a/GerbilManagerWebAPI/SaleAd/SaleAdService.cs
+++ b/GerbilManagerWebAPI/SaleAd/SaleAdService.cs
@@ -1,87 +1,35 @@
-using System.Net.Http.Headers;
-using System.Text;
-using System.Text.Json;
-using System.Text.Json.Serialization;
+using GerbilManagerWebAPI.Ai;
 using Microsoft.Extensions.Options;
 
 namespace GerbilManagerWebAPI.SaleAd
 {
     /// <summary>
-    /// FEAT-12a: provider-agnostic AI client for sale-ad generation.
-    ///
-    /// Speaks the OpenAI-compatible chat-completions wire shape — deliberately
-    /// WITHOUT any vendor SDK: a plain JSON POST to {AI:BaseUrl}/chat/completions
-    /// with a Bearer key covers Google Gemini (compat endpoint), Groq, Mistral,
-    /// local Ollama and any future provider. The wire shape IS the abstraction.
+    /// FEAT-12a: sale-ad generation. The provider-agnostic wire handling lives in
+    /// <see cref="OpenAiChatClient"/> (extracted in INBOX-2 so the reply-draft and
+    /// future AI features reuse the SAME implementation); this service contributes
+    /// the sale-ad prompts and the SaleAd-shaped result. Public surface unchanged.
     /// </summary>
     public sealed class SaleAdService(HttpClient http, IOptions<AiOptions> options)
     {
-        private static readonly JsonSerializerOptions JsonOptions = new()
-        {
-            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
-            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
-        };
+        private readonly OpenAiChatClient _client = new(http, options);
 
         public async Task<SaleAdResult> GenerateAsync(SaleAdRequest request, CancellationToken ct = default)
         {
-            var ai = options.Value;
-            if (!ai.IsConfigured)
+            var result = await _client.CompleteAsync(
+                SaleAdPromptBuilder.BuildSystemPrompt(),
+                SaleAdPromptBuilder.BuildUserPrompt(request),
+                ct);
+            var status = result.Status switch
             {
-                return new SaleAdResult(SaleAdStatus.NotConfigured, null,
-                    "KI-Anbieter ist nicht konfiguriert (AI__BaseUrl / AI__ApiKey / AI__Model).");
-            }
-
-            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"),
+                AiCallStatus.Ok => SaleAdStatus.Ok,
+                AiCallStatus.NotConfigured => SaleAdStatus.NotConfigured,
+                _ => SaleAdStatus.UpstreamError,
             };
-            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 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}");
-            }
+            return new SaleAdResult(status, result.Text, result.Error);
         }
 
-        /// <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");
-
-        // ── 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);
+            OpenAiChatClient.BuildCompletionsUri(baseUrl);
     }
 }