fix(analysis): refresh stale job summaries

JobTrackerApi.Tests/JobApplicationsEndpointBehaviorTests.cs

@@ -292,11 +292,79 @@ public sealed class JobApplicationsEndpointBehaviorTests
         Assert.Equal("NO", opportunity.CountryCode);
     }
 
-    private static JobApplicationsController CreateController(JobTrackerContext db, string userId)
+    [Fact]
+    public async Task Update_refreshes_analysis_only_when_the_advert_materially_changes()
     {
+        await using var db = CreateDb();
+        var company = new Company { Name = "Acme", OwnerUserId = "user-1" };
+        db.Companies.Add(company);
+        await db.SaveChangesAsync();
+
+        var originalDescription = "Build and operate C# services with SQL, Docker and Azure. Work with product teams to deliver reliable APIs.";
+        var job = new JobApplication
+        {
+            JobTitle = "Backend Developer",
+            CompanyId = company.Id,
+            OwnerUserId = "user-1",
+            Description = originalDescription,
+            ShortSummary = "Old analysis",
+        };
+        db.JobApplications.Add(job);
+        await db.SaveChangesAsync();
+
         var summarizer = new Mock<ISummarizerService>();
+        summarizer.Setup(service => service.SummarizeAsync(It.IsAny<string>(), 160, 60)).ReturnsAsync("Fresh analysis");
+        var user = new ApplicationUser { Id = "user-1", UserName = "user", AiEnabled = true };
+        var controller = CreateController(db, "user-1", summarizer, user, new[] { "Premium" });
+        var request = new UpdateJobApplicationRequest(
+            JobTitle: "Backend Developer",
+            CompanyId: company.Id,
+            Status: "Applied",
+            ResponseReceived: false,
+            ResponseDate: null,
+            Location: null,
+            Salary: null,
+            SalaryMin: null,
+            SalaryMax: null,
+            SalaryCurrency: null,
+            SalaryPeriod: null,
+            NextAction: null,
+            FollowUpAt: null,
+            Notes: null,
+            Description: "Lead a Kubernetes platform team building Go services for machine-learning workloads and distributed event streaming.",
+            TranslatedDescription: null,
+            DescriptionLanguage: "en",
+            Tags: null,
+            Deadline: null,
+            CoverLetterText: null,
+            JobUrl: null,
+            DateApplied: null,
+            FeedbackRequestedAt: null,
+            StatusChangedAt: null);
+
+        Assert.IsType<NoContentResult>(await controller.Update(job.Id, request, CancellationToken.None));
+
+        Assert.Equal("Fresh analysis", (await db.JobApplications.SingleAsync()).ShortSummary);
+        summarizer.Verify(service => service.SummarizeAsync(It.IsAny<string>(), 160, 60), Times.Once);
+        Assert.Contains(await db.JobEvents.ToListAsync(), item => item.Type == "AiRefreshed" && item.Note!.Contains("automatically"));
+
+        request = request with { Description = request.Description + "  " };
+        Assert.IsType<NoContentResult>(await controller.Update(job.Id, request, CancellationToken.None));
+        summarizer.Verify(service => service.SummarizeAsync(It.IsAny<string>(), 160, 60), Times.Once);
+    }
+
+    private static JobApplicationsController CreateController(
+        JobTrackerContext db,
+        string userId,
+        Mock<ISummarizerService>? summarizerOverride = null,
+        ApplicationUser? lookupUser = null,
+        IReadOnlyList<string>? roles = null)
+    {
+        var summarizer = summarizerOverride ?? new Mock<ISummarizerService>();
         summarizer.Setup(x => x.SummarizeSectionAsync(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<int>(), It.IsAny<int>())).ReturnsAsync("generated text");
-        var users = CreateUserManager();
+        var users = TestHostFactory.CreateUserManager(lookupUser);
+        if (lookupUser is not null)
+            users.Setup(manager => manager.GetRolesAsync(lookupUser)).ReturnsAsync(roles?.ToList() ?? new List<string>());
 
         var controller = new JobApplicationsController(db, summarizer.Object, users.Object);
         controller.ControllerContext = new ControllerContext
@@ -312,11 +380,6 @@ public sealed class JobApplicationsEndpointBehaviorTests
         return controller;
     }
 
-    private static Mock<Microsoft.AspNetCore.Identity.UserManager<ApplicationUser>> CreateUserManager()
-    {
-        return TestHostFactory.CreateUserManager();
-    }
-
     private static JobTrackerContext CreateDb()
     {
         return TestHostFactory.CreateInMemoryDb();

JobTrackerApi/Controllers/JobApplicationsController.cs

@@ -833,6 +833,9 @@ Canonical profile:
             var oldStatus = job.Status;
             var oldResponseReceived = job.ResponseReceived;
             var oldResponseDate = job.ResponseDate;
+            var previousJobTitle = job.JobTitle;
+            var previousDescription = job.Description;
+            var previousTranslatedDescription = job.TranslatedDescription;
 
             var title = (request.JobTitle ?? "").Trim();
             if (title.Length == 0) return BadRequest("Job title is required.");
@@ -868,6 +871,36 @@ Canonical profile:
             // Status may have changed above; keep DateApplied consistent with the stage.
             SyncAppliedDateWithHistory(job);
 
+            // The persisted short analysis is generated on create. Refresh it only when the source
+            // job content materially changes; opening the workspace or saving an unrelated field
+            // must never spend another AI call. Clear the old summary first so a failed refresh
+            // cannot present analysis for an advert the user has replaced.
+            if (HasSubstantialAnalysisChange(
+                previousJobTitle, previousDescription, previousTranslatedDescription,
+                job.JobTitle, job.Description, job.TranslatedDescription))
+            {
+                job.ShortSummary = null;
+                try
+                {
+                    if (await CanCurrentUserUseAiAsync(cancellationToken))
+                    {
+                        job.ShortSummary = await _summarizer.SummarizeAsync(BuildSummarySource(job), 160, 60);
+                        _db.JobEvents.Add(new JobEvent
+                        {
+                            JobApplicationId = job.Id,
+                            Type = "AiRefreshed",
+                            Note = "Job analysis automatically refreshed after the advert changed.",
+                            At = DateTime.Now,
+                        });
+                    }
+                }
+                catch
+                {
+                    // Editing the application must still succeed if the optional analysis provider
+                    // is unavailable. The manual refresh action remains available.
+                }
+            }
+
             if (oldResponseReceived != job.ResponseReceived || oldResponseDate != job.ResponseDate)
             {
                 _db.JobEvents.Add(new JobEvent
@@ -887,6 +920,43 @@ Canonical profile:
             return NoContent();
         }
 
+        private static bool HasSubstantialAnalysisChange(
+            string? previousTitle,
+            string? previousDescription,
+            string? previousTranslatedDescription,
+            string? currentTitle,
+            string? currentDescription,
+            string? currentTranslatedDescription)
+        {
+            if (!string.Equals(NormalizeAnalysisText(previousTitle), NormalizeAnalysisText(currentTitle), StringComparison.Ordinal))
+                return true;
+
+            var before = NormalizeAnalysisText($"{previousDescription} {previousTranslatedDescription}");
+            var after = NormalizeAnalysisText($"{currentDescription} {currentTranslatedDescription}");
+            if (before == after) return false;
+            if (before.Length == 0 || after.Length == 0) return true;
+
+            var lengthChange = Math.Abs(before.Length - after.Length);
+            if (lengthChange >= Math.Max(80, before.Length / 10)) return true;
+
+            var beforeTokens = before.Split(' ', StringSplitOptions.RemoveEmptyEntries).ToHashSet(StringComparer.Ordinal);
+            var afterTokens = after.Split(' ', StringSplitOptions.RemoveEmptyEntries).ToHashSet(StringComparer.Ordinal);
+            var union = beforeTokens.Union(afterTokens).Count();
+            if (union == 0) return false;
+            var overlap = beforeTokens.Intersect(afterTokens).Count();
+            return 1d - overlap / (double)union >= 0.12d;
+        }
+
+        private static string NormalizeAnalysisText(string? value)
+        {
+            if (string.IsNullOrWhiteSpace(value)) return string.Empty;
+            var words = value.ToLowerInvariant()
+                .Split((char[]?)null, StringSplitOptions.RemoveEmptyEntries)
+                .Select(word => word.Trim().Trim(',', '.', ':', ';', '!', '?', '-', '–', '—', '(', ')', '[', ']', '"', '\''))
+                .Where(word => word.Length > 0);
+            return string.Join(' ', words);
+        }
+
         /// <summary>Canonical ordered pipeline stages so the UI renders one source of truth.</summary>
         [HttpGet("pipeline")]
         public ActionResult<IEnumerable<PipelineStageDto>> GetPipeline()