Let reviews see low-confidence suggestions and rebase preview applies

A low-confidence answer was discarded inside Classify, so Analyse showed
the row as unchanged instead of a reviewable suggestion; the fallback
decision moves to the import path, which keeps the merchant link and the
recorded confidence. ApplyPreview now rebases onto the current journal:
unrelated commits during a minutes-long paced run no longer invalidate
the review, only an edit to a selected transaction itself conflicts, and
applied changes are pruned so the rest stay appliable.

internal/app/reclassify.go

@@ -276,6 +276,21 @@ func classifyRange(ctx context.Context, client *classification.Client, s State,
 	p.NewMerchants = append([]domain.Merchant{}, s.Data.Merchants[baseMerchants:]...)
 	return p, nil
 }
+// enrichmentEqual compares enrichment semantically: tag order is not a change.
+func enrichmentEqual(a, b domain.Enrichment) bool {
+	a.TagIDs = slices.Clone(a.TagIDs)
+	b.TagIDs = slices.Clone(b.TagIDs)
+	slices.Sort(a.TagIDs)
+	slices.Sort(b.TagIDs)
+	return reflect.DeepEqual(a, b)
+}
+
+// ApplyPreview rebases the selected proposals onto the current journal. A
+// preview run is minutes long by design, so unrelated commits (a scheduled
+// sync, an import, an earlier partial apply of this same preview) must not
+// invalidate the review; only a selected transaction whose own enrichment
+// changed since the preview snapshot conflicts. Applied changes are pruned so
+// the remaining proposals stay appliable without another paced provider run.
 func (a *App) ApplyPreview(ctx context.Context, id, rev string, ids []string) (State, error) {
 	a.mu.Lock()
 	defer a.mu.Unlock()
@@ -290,12 +305,9 @@ func (a *App) ApplyPreview(ctx context.Context, id, rev string, ids []string) (S
 	if err != nil {
 		return State{}, err
 	}
-	if s.Revision != rev {
-		return State{}, errors.New("revision conflict: data changed after preview; analyse again")
-	}
-	changes := map[string]domain.Enrichment{}
+	changes := map[string]Change{}
 	for _, c := range p.Changes {
-		changes[c.ID] = c.After
+		changes[c.ID] = c
 	}
 	selected := map[string]bool{}
 	for _, id := range ids {
@@ -307,16 +319,29 @@ func (a *App) ApplyPreview(ctx context.Context, id, rev string, ids []string) (S
 	if len(selected) == 0 {
 		return State{}, errors.New("select at least one change")
 	}
+	applied := 0
 	needed := map[string]bool{}
 	for i, t := range s.Data.Transactions {
 		if !selected[t.Facts.ID] {
 			continue
 		}
-		s.Data.Transactions[i].Enrichment = changes[t.Facts.ID]
-		needed[changes[t.Facts.ID].MerchantID] = true
+		c := changes[t.Facts.ID]
+		if !enrichmentEqual(t.Enrichment, c.Before) {
+			return State{}, errors.New("revision conflict: a selected transaction changed after the preview; analyse it again")
+		}
+		s.Data.Transactions[i].Enrichment = c.After
+		needed[c.After.MerchantID] = true
+		applied++
+	}
+	if applied != len(selected) {
+		return State{}, errors.New("revision conflict: a selected transaction no longer exists; analyse again")
+	}
+	existing := map[string]bool{}
+	for _, m := range s.Data.Merchants {
+		existing[m.ID] = true
 	}
 	for _, m := range p.NewMerchants {
-		if needed[m.ID] {
+		if needed[m.ID] && !existing[m.ID] {
 			s.Data.Merchants = append(s.Data.Merchants, m)
 		}
 	}
@@ -327,14 +352,25 @@ func (a *App) ApplyPreview(ctx context.Context, id, rev string, ids []string) (S
 			LearnAlias(&s.Data, t.Facts, t.Enrichment.MerchantID)
 		}
 	}
-	state, err := a.commit(ctx, rev, s.Data)
+	state, err := a.commit(ctx, s.Revision, s.Data)
 	if err != nil {
 		return State{}, err
 	}
-	delete(a.previews, id)
-	if job := a.previewRun; job != nil && job.status.ID == id {
-		a.previewRun = nil
+	kept := make([]Change, 0, len(p.Changes)-applied)
+	for _, c := range p.Changes {
+		if !selected[c.ID] {
+			kept = append(kept, c)
+		}
 	}
+	if len(kept) == 0 {
+		delete(a.previews, id)
+		if job := a.previewRun; job != nil && job.status.ID == id {
+			a.previewRun = nil
+		}
+		return state, nil
+	}
+	p.Changes = kept
+	a.previews[id] = p
 	return state, nil
 }