feat(ai): enforce local-first routing

Keep external providers behind server consent, task, and prompt-cost gates while persisting actual provider provenance.

JobTrackerApi.Tests/AiWorkspaceTests.cs

@@ -14,6 +14,8 @@ public sealed class AiWorkspaceTests
         public string? Next = "## Result\nGenerated suggestion.";
         public int Calls;
         public string? LastInstruction;
+        public string? ActualProvider;
+        public string? FallbackReason;
         // The source text the module assembled — what the prompt actually saw.
         public string? LastText;
         public Task<string?> SummarizeSectionAsync(string instruction, string text, int maxLength = 180, int minLength = 40)
@@ -24,6 +26,17 @@ public sealed class AiWorkspaceTests
             return Task.FromResult(Next);
         }
         public Task<string?> SummarizeAsync(string text, int maxLength = 150, int minLength = 30) => Task.FromResult(Next);
+        public async Task<AiGenerationResult?> GenerateSectionWithMetadataAsync(
+            string instruction,
+            string text,
+            int maxLength = 180,
+            int minLength = 40,
+            CancellationToken cancellationToken = default)
+        {
+            var generated = await SummarizeSectionAsync(instruction, text, maxLength, minLength);
+            return generated is null ? null : new AiGenerationResult(generated, ActualProvider, "test-model", FallbackReason,
+                FallbackReason is null ? "local_primary" : "external_fallback");
+        }
         public Task<AiTextExtractionResult?> ExtractTextAsync(Stream stream, string fileName, string? contentType = null, CancellationToken cancellationToken = default) => throw new NotImplementedException();
         public Task RunProbeAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
         public Task<AiServiceMetrics> GetMetricsAsync(CancellationToken cancellationToken = default) => throw new NotImplementedException();
@@ -72,6 +85,22 @@ public sealed class AiWorkspaceTests
         Assert.Single(await db.AiInteractions.IgnoreQueryFilters().Where(x => x.JobApplicationId == jobId).ToListAsync());
     }
 
+    [Fact]
+    public async Task Generate_records_the_actual_provider_and_fallback_metadata()
+    {
+        var (db, svc, ai) = New("user-1");
+        await using var _ = db;
+        ai.ActualProvider = "groq";
+        ai.FallbackReason = "local_circuit_open";
+        var jobId = await SeedJobAsync(db, "user-1");
+
+        var result = await svc.GenerateAsync("user-1", jobId, "cv", "Ada", Req("job-analysis"), "configured-label", default);
+
+        Assert.Equal("groq", result!.Provider);
+        Assert.Contains("local_circuit_open", result.ResultJson);
+        Assert.Contains("test-model", result.ResultJson);
+    }
+
     [Fact]
     public async Task Cover_letter_normalizes_an_unknown_mode_and_labels_the_title()
     {