Warn about vectors written before the marker existed

internal/store/meta_test.go

@@ -3,6 +3,7 @@ package store
 import (
 	"context"
 	"testing"
+	"time"
 )
 
 // A fresh DB has no marker yet, so the current embedder is recorded and
@@ -30,6 +31,38 @@ func TestCheckEmbedderFreshDBRecords(t *testing.T) {
 	}
 }
 
+// The deployed box: notes were written by the old embedder, before the marker
+// existed. Claiming them for the current one would hide exactly the problem
+// the marker is for, so an unmarked DB that already holds vectors is a
+// mismatch.
+func TestCheckEmbedderUnmarkedDBWithVectorsIsMismatch(t *testing.T) {
+	s := newTestStore(t)
+	ctx := context.Background()
+
+	if _, err := s.WriteNote(ctx, time.Now(), "молоко в холодильнике", []float32{0.1, 0.2}, "voice"); err != nil {
+		t.Fatalf("WriteNote: %v", err)
+	}
+
+	stored, mismatch, err := s.CheckEmbedder(ctx, "multilingual-e5-small@384")
+	if err != nil {
+		t.Fatalf("CheckEmbedder: %v", err)
+	}
+	if !mismatch {
+		t.Fatal("an unmarked DB with stored vectors should report a mismatch")
+	}
+	if stored != EmbedderUnknown {
+		t.Fatalf("stored = %q, want %q", stored, EmbedderUnknown)
+	}
+	// It must NOT claim the DB — that would silence the warning on restart.
+	got, err := s.Meta(ctx, metaKeyEmbedderID)
+	if err != nil {
+		t.Fatalf("Meta: %v", err)
+	}
+	if got != "" {
+		t.Fatalf("marker written despite unknown provenance: %q", got)
+	}
+}
+
 // Both models are 384-dim, so this is the only thing that catches the swap.
 func TestCheckEmbedderDifferentModelMismatch(t *testing.T) {
 	s := newTestStore(t)