diff --git a/internal/router/embedderid_test.go b/internal/router/embedderid_test.go
index 03f1e16..6b2ecfd 100644
--- a/internal/router/embedderid_test.go
+++ b/internal/router/embedderid_test.go
@@ -1,10 +1,13 @@
 package router
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
 
 func TestEmbedderIDFromModelPath(t *testing.T) {
 	got := modelIDFromPath("/opt/maven/models/embedder/multilingual-e5-small.onnx")
-	if got != "multilingual-e5-small@384" {
+	if got != "multilingual-e5-small@384/tok2" {
 		t.Fatalf("modelIDFromPath = %q", got)
 	}
 	// A different model file must produce a different id, even at 384 dim.
@@ -12,6 +15,13 @@ func TestEmbedderIDFromModelPath(t *testing.T) {
 	if old == got {
 		t.Fatal("two different models share one id")
 	}
+	// The tokenizer is half of what makes a vector, and it changes under a
+	// model file whose name never moves (V-664). An id that ignored it would
+	// leave stored passages in one space and every new query in another, with
+	// nothing to trigger the re-embed.
+	if !strings.Contains(got, "/tok") {
+		t.Fatalf("id %q does not name the tokenizer revision", got)
+	}
 }
 
 func TestEmbedderIDIncludesDim(t *testing.T) {
diff --git a/internal/router/onnxembedder.go b/internal/router/onnxembedder.go
index cbbf63c..005255f 100644
--- a/internal/router/onnxembedder.go
+++ b/internal/router/onnxembedder.go
@@ -66,12 +66,19 @@ func NewONNXEmbedder(modelPath, tokenizerPath, libPath string) (*onnxEmbedder, e
 func (e *onnxEmbedder) Dim() int { return embedDim }
 
 // ID names the loaded model for the DB marker (Vikunja #378): the model file's
-// own name plus the dimension, so pointing the config at another model changes
-// the string on its own.
+// own name, the dimension, and the tokenizer revision, so pointing the config
+// at another model changes the string on its own.
 func (e *onnxEmbedder) ID() string { return e.id }
 
+// tokenizerRev — bumped whenever the tokenizer changes what it emits for the
+// same text, because that changes every vector while the model file's name
+// stays put. Rev 2 is the fix for the reversed word pieces (V-664): stored
+// passages embedded under rev 1 no longer sit in the same space as a query
+// embedded now, and ReembedAll rewrites them because this string moved.
+const tokenizerRev = 2
+
 // modelIDFromPath turns /opt/.../multilingual-e5-small.onnx into
-// "multilingual-e5-small@384".
+// "multilingual-e5-small@384/tok2".
 func modelIDFromPath(modelPath string) string {
 	name := modelPath
 	if i := strings.LastIndexAny(name, "/\\"); i >= 0 {
@@ -81,7 +88,7 @@ func modelIDFromPath(modelPath string) string {
 	if name == "" {
 		name = "onnx"
 	}
-	return fmt.Sprintf("%s@%d", name, embedDim)
+	return fmt.Sprintf("%s@%d/tok%d", name, embedDim, tokenizerRev)
 }
 
 // Embed treats the text as a query. The classifier compares one short
@@ -339,14 +346,17 @@ func (t *unigramTokenizer) encodeWord(word string) []int64 {
 		}
 	}
 
+	// Backtracking walks the word from its end, and prepending each piece puts
+	// it back in reading order. There used to be a second reverse after this
+	// loop, which undid it: every multi-piece word came out backwards, and
+	// "query: вода" tokenized to [0 12 1294 41 12489 2] where the reference
+	// tokenizer gives [0 41 1294 12 12489 2] (V-664). A transformer reads
+	// position, so the pieces of a long Russian word were being read in the
+	// wrong order on every turn.
 	var result []int64
 	for i := n; i > 0; i = prev[i] {
 		result = append([]int64{bestID[i]}, result...)
 	}
-	// Reverse
-	for l, r := 0, len(result)-1; l < r; l, r = l+1, r-1 {
-		result[l], result[r] = result[r], result[l]
-	}
 	return result
 }