From 591c9b8a648799a182050672160b70985105421f Mon Sep 17 00:00:00 2001
From: cesnimda <dj@cesnimda.co.uk>
Date: Sat, 11 Apr 2026 21:55:51 +0200
Subject: [PATCH] Clamp AI summarize lengths for CV rewrite

---
 JobTrackerApi.Tests/SummarizerServiceTests.cs | 49 +++++++++++++++++++
 JobTrackerApi/Services/SummarizerService.cs   | 15 +++++-
 2 files changed, 62 insertions(+), 2 deletions(-)
 create mode 100644 JobTrackerApi.Tests/SummarizerServiceTests.cs

diff --git a/JobTrackerApi.Tests/SummarizerServiceTests.cs b/JobTrackerApi.Tests/SummarizerServiceTests.cs
new file mode 100644
index 0000000..c7d317a
--- /dev/null
+++ b/JobTrackerApi.Tests/SummarizerServiceTests.cs
@@ -0,0 +1,49 @@
+using System.Net;
+using System.Net.Http;
+using System.Text;
+using Microsoft.Extensions.Caching.Memory;
+using Moq;
+using Xunit;
+using JobTrackerApi.Services;
+
+namespace JobTrackerApi.Tests;
+
+public sealed class SummarizerServiceTests
+{
+    [Fact]
+    public async Task Summarize_section_clamps_lengths_to_ai_service_limits()
+    {
+        var handler = new CapturingHandler();
+        var httpClient = new HttpClient(handler)
+        {
+            BaseAddress = new Uri("http://localhost:8001")
+        };
+
+        var httpFactory = new Mock<IHttpClientFactory>();
+        httpFactory.Setup(x => x.CreateClient("ai-service")).Returns(httpClient);
+
+        using var memoryCache = new MemoryCache(new MemoryCacheOptions());
+        var service = new SummarizerService(httpFactory.Object, memoryCache);
+
+        var result = await service.SummarizeSectionAsync("Rewrite this CV", "Professional Summary\nBuilt backend systems.", 1800, 400);
+
+        Assert.Equal("ok", result);
+        Assert.NotNull(handler.LastBody);
+        Assert.Contains("\"max_length\":256", handler.LastBody);
+        Assert.Contains("\"min_length\":180", handler.LastBody);
+    }
+
+    private sealed class CapturingHandler : HttpMessageHandler
+    {
+        public string? LastBody { get; private set; }
+
+        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            LastBody = request.Content is null ? null : await request.Content.ReadAsStringAsync(cancellationToken);
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("{\"summary\":\"ok\"}", Encoding.UTF8, "application/json")
+            };
+        }
+    }
+}
diff --git a/JobTrackerApi/Services/SummarizerService.cs b/JobTrackerApi/Services/SummarizerService.cs
index 404a184..8942c1c 100644
--- a/JobTrackerApi/Services/SummarizerService.cs
+++ b/JobTrackerApi/Services/SummarizerService.cs
@@ -76,6 +76,10 @@ namespace JobTrackerApi.Services
     public class SummarizerService : ISummarizerService
     {
         private const int AiSummarizeMaxInputChars = 20000;
+        private const int AiServiceMaxSummaryLength = 256;
+        private const int AiServiceMaxMinLength = 180;
+        private const int AiServiceMinSummaryLength = 24;
+        private const int AiServiceMinMinLength = 8;
         private readonly IHttpClientFactory _httpFactory;
         private readonly IMemoryCache _cache;
         private readonly object _metricsLock = new();
@@ -172,7 +176,14 @@ namespace JobTrackerApi.Services
 
         private async Task<string?> SummarizeCoreAsync(string text, int maxLength, int minLength)
         {
-            var key = BuildCacheKey(text, maxLength, minLength);
+            var normalizedMaxLength = Math.Clamp(maxLength, AiServiceMinSummaryLength, AiServiceMaxSummaryLength);
+            var normalizedMinLength = Math.Clamp(minLength, AiServiceMinMinLength, AiServiceMaxMinLength);
+            if (normalizedMinLength >= normalizedMaxLength)
+            {
+                normalizedMinLength = Math.Max(AiServiceMinMinLength, normalizedMaxLength - 1);
+            }
+
+            var key = BuildCacheKey(text, normalizedMaxLength, normalizedMinLength);
             Interlocked.Increment(ref _requests);
 
             if (_cache.TryGetValue<string>(key, out var cached))
@@ -189,7 +200,7 @@ namespace JobTrackerApi.Services
             Interlocked.Increment(ref _cacheMisses);
 
             var client = _httpFactory.CreateClient("ai-service");
-            var payload = JsonSerializer.Serialize(new { text, max_length = maxLength, min_length = minLength });
+            var payload = JsonSerializer.Serialize(new { text, max_length = normalizedMaxLength, min_length = normalizedMinLength });
             using var content = new StringContent(payload, Encoding.UTF8, "application/json");
             var sw = Stopwatch.StartNew();