feat: deterministic email-driven status suggestions

New EmailStatusClassifier scans a message subject/body for outcome
signals (interview invite, offer, rejection) and suggests a canonical
pipeline status. Priority-ordered so a rejection that mentions the prior
interview still classifies as Rejected. Deterministic - no AI - so it is
instant, reproducible, and safe.

- GET /api/jobapplications/{id}/status-suggestion reads the job's latest
  inbound correspondence (incl. Gmail imports) and suggests a forward
  status move, suppressed when already in/past that stage
- always human-confirmed via the existing PATCH .../status
- 7 classifier unit tests + 2 endpoint integration tests; backend green (133)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

JobTrackerApi.Tests/EmailStatusClassifierTests.cs

@@ -0,0 +1,61 @@
+using JobTrackerApi.Services;
+using Xunit;
+
+namespace JobTrackerApi.Tests;
+
+public sealed class EmailStatusClassifierTests
+{
+    [Fact]
+    public void Detects_rejection()
+    {
+        var s = EmailStatusClassifier.Classify("Your application", "Thank you for your time. Unfortunately, we have decided not to proceed with your application.");
+        Assert.NotNull(s);
+        Assert.Equal("Rejected", s!.SuggestedStatus);
+    }
+
+    [Fact]
+    public void Detects_offer()
+    {
+        var s = EmailStatusClassifier.Classify("Great news", "We are pleased to offer you the position of Backend Engineer.");
+        Assert.NotNull(s);
+        Assert.Equal("Offer", s!.SuggestedStatus);
+    }
+
+    [Fact]
+    public void Detects_interview_invite()
+    {
+        var s = EmailStatusClassifier.Classify("Next steps", "We would like to invite you to interview next week. What is your availability for a call?");
+        Assert.NotNull(s);
+        Assert.Equal("Interview", s!.SuggestedStatus);
+    }
+
+    [Fact]
+    public void Rejection_wins_over_interview_mention()
+    {
+        // A rejection email that references the interview the candidate had must classify as Rejected.
+        var s = EmailStatusClassifier.Classify(
+            "Update on your application",
+            "Thank you for taking the time to interview with us. Unfortunately, we will not be moving forward.");
+        Assert.NotNull(s);
+        Assert.Equal("Rejected", s!.SuggestedStatus);
+    }
+
+    [Fact]
+    public void Weak_interview_cue_is_low_confidence()
+    {
+        var s = EmailStatusClassifier.Classify("Coding challenge", "Please complete this take-home assessment.");
+        Assert.NotNull(s);
+        Assert.Equal("Interview", s!.SuggestedStatus);
+        Assert.Equal("low", s.Confidence);
+    }
+
+    [Fact]
+    public void Returns_null_for_neutral_email()
+    {
+        Assert.Null(EmailStatusClassifier.Classify("Re: question", "Thanks for the info, that answers my question about the parking."));
+    }
+
+    [Fact]
+    public void Handles_empty_input()
+        => Assert.Null(EmailStatusClassifier.Classify(null, null));
+}

JobTrackerApi.Tests/JobApplicationsEndpointBehaviorTests.cs

@@ -56,6 +56,68 @@ public sealed class JobApplicationsEndpointBehaviorTests
         Assert.Contains("Profile page", badRequest.Value?.ToString());
     }
 
+    [Fact]
+    public async Task Status_suggestion_from_latest_inbound_rejection()
+    {
+        await using var db = CreateDb();
+        var company = new Company { Name = "Acme", OwnerUserId = "user-1" };
+        db.Companies.Add(company);
+        await db.SaveChangesAsync();
+
+        var job = new JobApplication { JobTitle = "Dev", CompanyId = company.Id, OwnerUserId = "user-1", Status = "Applied" };
+        db.JobApplications.Add(job);
+        await db.SaveChangesAsync();
+
+        db.Correspondences.Add(new Correspondence
+        {
+            JobApplicationId = job.Id,
+            From = "Company",
+            Direction = "inbound",
+            Subject = "Update",
+            Content = "Unfortunately, we have decided not to proceed.",
+            Date = DateTime.Now,
+        });
+        await db.SaveChangesAsync();
+
+        var controller = CreateController(db, "user-1");
+        var result = await controller.GetStatusSuggestion(job.Id, CancellationToken.None);
+
+        var ok = Assert.IsType<OkObjectResult>(result.Result);
+        var dto = Assert.IsType<JobApplicationsController.StatusSuggestionDto>(ok.Value);
+        Assert.True(dto.HasSuggestion);
+        Assert.Equal("Rejected", dto.SuggestedStatus);
+    }
+
+    [Fact]
+    public async Task Status_suggestion_suppressed_when_already_in_stage()
+    {
+        await using var db = CreateDb();
+        var company = new Company { Name = "Acme", OwnerUserId = "user-1" };
+        db.Companies.Add(company);
+        await db.SaveChangesAsync();
+
+        var job = new JobApplication { JobTitle = "Dev", CompanyId = company.Id, OwnerUserId = "user-1", Status = "Rejected" };
+        db.JobApplications.Add(job);
+        await db.SaveChangesAsync();
+
+        db.Correspondences.Add(new Correspondence
+        {
+            JobApplicationId = job.Id,
+            From = "Company",
+            Direction = "inbound",
+            Content = "Unfortunately, we will not be moving forward.",
+            Date = DateTime.Now,
+        });
+        await db.SaveChangesAsync();
+
+        var controller = CreateController(db, "user-1");
+        var result = await controller.GetStatusSuggestion(job.Id, CancellationToken.None);
+
+        var ok = Assert.IsType<OkObjectResult>(result.Result);
+        var dto = Assert.IsType<JobApplicationsController.StatusSuggestionDto>(ok.Value);
+        Assert.False(dto.HasSuggestion);
+    }
+
     [Fact]
     public async Task Match_score_scores_job_against_profile_cv()
     {

JobTrackerApi/Controllers/JobApplicationsController.cs

@@ -1604,6 +1604,57 @@ Canonical profile:
             return NoContent();
         }
 
+        public sealed record StatusSuggestionDto(
+            bool HasSuggestion,
+            string? SuggestedStatus,
+            string? CurrentStatus,
+            string? Signal,
+            string? Confidence,
+            DateTime? MessageDate,
+            string? MessageSubject);
+
+        /// <summary>
+        /// Suggests a pipeline status from the job's most recent inbound message (e.g. an interview
+        /// invite or rejection). Deterministic and always human-confirmed via PATCH .../status.
+        /// </summary>
+        [HttpGet("{id:int}/status-suggestion")]
+        public async Task<ActionResult<StatusSuggestionDto>> GetStatusSuggestion([FromRoute] int id, CancellationToken cancellationToken)
+        {
+            var job = await _db.JobApplications.FirstOrDefaultAsync(j => j.Id == id, cancellationToken);
+            if (job is null) return NotFound();
+
+            var none = new StatusSuggestionDto(false, null, job.Status, null, null, null, null);
+
+            var latestInbound = await _db.Correspondences
+                .AsNoTracking()
+                .Where(c => c.JobApplicationId == id
+                    && c.Direction != "outbound"
+                    && c.From != "Me")
+                .OrderByDescending(c => c.Date)
+                .FirstOrDefaultAsync(cancellationToken);
+            if (latestInbound is null) return Ok(none);
+
+            var suggestion = EmailStatusClassifier.Classify(latestInbound.Subject, latestInbound.Content);
+            if (suggestion is null) return Ok(none);
+
+            // Don't nag when the job is already in (or past) the suggested stage.
+            var currentOrder = JobPipeline.OrderOf(job.Status);
+            var suggestedOrder = JobPipeline.OrderOf(suggestion.SuggestedStatus);
+            if (JobPipeline.Normalize(job.Status) == suggestion.SuggestedStatus || currentOrder >= suggestedOrder)
+            {
+                return Ok(none);
+            }
+
+            return Ok(new StatusSuggestionDto(
+                HasSuggestion: true,
+                SuggestedStatus: suggestion.SuggestedStatus,
+                CurrentStatus: job.Status,
+                Signal: suggestion.Signal,
+                Confidence: suggestion.Confidence,
+                MessageDate: latestInbound.Date,
+                MessageSubject: latestInbound.Subject));
+        }
+
 
         [HttpPost("{id:int}/refresh-ai")]
         public async Task<ActionResult<JobApplicationDto>> RefreshAi([FromRoute] int id, CancellationToken cancellationToken)

JobTrackerApi/Services/EmailStatusClassifier.cs

@@ -0,0 +1,61 @@
+namespace JobTrackerApi.Services
+{
+    public sealed record EmailStatusSuggestion(string SuggestedStatus, string Signal, string Confidence);
+
+    /// <summary>
+    /// Deterministic email → pipeline-status classifier. Scans subject/body for outcome signals and
+    /// suggests a canonical status. No AI: instant, reproducible, and safe (the user always confirms).
+    /// Priority matters — a rejection email often still mentions "interview", so rejection wins.
+    /// </summary>
+    public static class EmailStatusClassifier
+    {
+        // Ordered highest-priority first. Each stage lists lowercase phrases to look for.
+        private static readonly (string Status, string Confidence, string[] Phrases)[] Rules =
+        {
+            ("Rejected", "high", new[]
+            {
+                "regret to inform", "we regret", "unfortunately, we", "not moving forward",
+                "not be moving forward", "decided not to proceed", "will not be proceeding",
+                "not to proceed", "not been selected", "will not be progressing",
+                "unable to offer", "position has been filled", "no longer being considered",
+                "decided to move forward with other", "pursue other candidates",
+                "not to move forward", "were not successful", "was not successful",
+            }),
+            ("Offer", "high", new[]
+            {
+                "pleased to offer", "delighted to offer", "happy to offer", "offer of employment",
+                "job offer", "we would like to offer", "formal offer", "extend an offer",
+                "offer letter", "excited to offer",
+            }),
+            ("Interview", "medium", new[]
+            {
+                "invite you to interview", "invite you to an interview", "schedule an interview",
+                "would like to invite you", "phone screen", "phone interview", "video interview",
+                "technical interview", "next steps in the", "your availability for a call",
+                "availability for an interview", "set up a call", "set up an interview",
+                "meet the team", "book a time", "invitation to interview", "interview invitation",
+                "like to speak with you", "move to the interview",
+            }),
+        };
+
+        // Weaker single-word cues only fire when no strong phrase matched (kept low-confidence).
+        private static readonly string[] InterviewWeakCues = { "interview", "assessment", "coding challenge", "take-home" };
+
+        public static EmailStatusSuggestion? Classify(string? subject, string? body)
+        {
+            var text = $"{subject}\n{body}".ToLowerInvariant();
+            if (string.IsNullOrWhiteSpace(text)) return null;
+
+            foreach (var (status, confidence, phrases) in Rules)
+            {
+                var hit = phrases.FirstOrDefault(p => text.Contains(p, StringComparison.Ordinal));
+                if (hit is not null) return new EmailStatusSuggestion(status, hit, confidence);
+            }
+
+            var weak = InterviewWeakCues.FirstOrDefault(c => text.Contains(c, StringComparison.Ordinal));
+            if (weak is not null) return new EmailStatusSuggestion("Interview", weak, "low");
+
+            return null;
+        }
+    }
+}