Ignore status reports older than the stored generation

internal/store/store.go

@@ -281,13 +281,17 @@ func (s *Store) UpsertDevice(ctx context.Context, d model.Device) error {
 }
 
 // RecordDeviceStatus stores an agent's apply report. reported_generation only
-// advances on applied; every report updates the last-status columns.
+// advances on applied; the last-status columns only take reports at or above
+// the stored status generation, so late or replayed reports never clobber newer state.
 func (s *Store) RecordDeviceStatus(ctx context.Context, name string, r model.StatusReport) error {
 	tag, err := s.pool.Exec(ctx, `
 		UPDATE devices SET
-			reported_generation = CASE WHEN $2 = 'applied' THEN $3 ELSE reported_generation END,
-			status = $2, status_generation = $3, status_error = $4,
-			status_at = now(), last_seen = now()
+			reported_generation = CASE WHEN $2 = 'applied' THEN GREATEST(reported_generation, $3) ELSE reported_generation END,
+			status = CASE WHEN $3 >= status_generation THEN $2 ELSE status END,
+			status_error = CASE WHEN $3 >= status_generation THEN $4 ELSE status_error END,
+			status_at = CASE WHEN $3 >= status_generation THEN now() ELSE status_at END,
+			status_generation = GREATEST(status_generation, $3),
+			last_seen = now()
 		WHERE name = $1`,
 		name, string(r.Status), r.Generation, r.Error)
 	if err != nil {

internal/store/store_integration_test.go

@@ -196,7 +196,27 @@ func TestRecordDeviceStatus(t *testing.T) {
 		t.Errorf("failed must not advance applied generation: %+v", got)
 	}
 
-	if err := s.RecordDeviceStatus(ctx, "fw1", model.StatusReport{Status: "bogus", Generation: 9}); err == nil {
+	got = report(model.StatusReport{Status: model.StatusApplied, Generation: 9})
+	if got.AppliedGeneration != 9 || got.Status != model.StatusApplied || got.Generation != 9 {
+		t.Errorf("applied 9: %+v", got)
+	}
+
+	got = report(model.StatusReport{Status: model.StatusApplied, Generation: 4})
+	if got.AppliedGeneration != 9 || got.Status != model.StatusApplied || got.Generation != 9 {
+		t.Errorf("older applied must not regress: %+v", got)
+	}
+
+	got = report(model.StatusReport{Status: model.StatusReverted, Generation: 8, Error: "stale"})
+	if got.AppliedGeneration != 9 || got.Status != model.StatusApplied || got.Generation != 9 || got.Error != "" {
+		t.Errorf("older reverted must not overwrite newer status: %+v", got)
+	}
+
+	got = report(model.StatusReport{Status: model.StatusReverted, Generation: 9, Error: "lost api"})
+	if got.AppliedGeneration != 9 || got.Status != model.StatusReverted || got.Generation != 9 || got.Error != "lost api" {
+		t.Errorf("same-generation reverted after applied must update: %+v", got)
+	}
+
+	if err := s.RecordDeviceStatus(ctx, "fw1", model.StatusReport{Status: "bogus", Generation: 10}); err == nil {
 		t.Error("db should reject unknown status")
 	}
 	if err := s.RecordDeviceStatus(ctx, "nope", model.StatusReport{Status: model.StatusApplied}); err != store.ErrNotFound {