diff --git a/pkg/memory/jsonl.go b/pkg/memory/jsonl.go
index 13f450835..6e6722b96 100644
--- a/pkg/memory/jsonl.go
+++ b/pkg/memory/jsonl.go
@@ -328,15 +328,16 @@ func (s *JSONLStore) TruncateHistory(
 		return err
 	}
 
-	// If the meta count might be stale (e.g. after a crash during
-	// addMsg), reconcile with the actual line count on disk.
-	if meta.Count == 0 {
-		n, countErr := countLines(s.jsonlPath(sessionKey))
-		if countErr != nil {
-			return countErr
-		}
-		meta.Count = n
+	// Always reconcile meta.Count with the actual line count on disk.
+	// A crash between the JSONL append and the meta update in addMsg
+	// leaves meta.Count stale (e.g. file has 101 lines but meta says
+	// 100). Counting lines is cheap — no unmarshal, just a scan — and
+	// TruncateHistory is not a hot path, so always re-count.
+	n, countErr := countLines(s.jsonlPath(sessionKey))
+	if countErr != nil {
+		return countErr
 	}
+	meta.Count = n
 
 	if keepLast <= 0 {
 		meta.Skip = meta.Count
diff --git a/pkg/memory/jsonl_test.go b/pkg/memory/jsonl_test.go
index 779cab041..356ff14ff 100644
--- a/pkg/memory/jsonl_test.go
+++ b/pkg/memory/jsonl_test.go
@@ -544,6 +544,57 @@ func TestCompact_ThenAppend(t *testing.T) {
 	}
 }
 
+func TestTruncateHistory_StaleMetaCount(t *testing.T) {
+	// Simulates a crash between JSONL append and meta update in addMsg:
+	// file has N+1 lines but meta.Count is still N. TruncateHistory must
+	// reconcile with the real line count so that keepLast is accurate.
+	store := newTestStore(t)
+	ctx := context.Background()
+
+	// Write 10 messages normally (meta.Count = 10).
+	for i := 0; i < 10; i++ {
+		err := store.AddMessage(ctx, "stale", "user", string(rune('a'+i)))
+		if err != nil {
+			t.Fatalf("AddMessage: %v", err)
+		}
+	}
+
+	// Simulate crash: append a line to JSONL but do NOT update meta.
+	// This leaves meta.Count = 10 while the file has 11 lines.
+	jsonlPath := store.jsonlPath("stale")
+	f, err := os.OpenFile(jsonlPath, os.O_WRONLY|os.O_APPEND, 0o644)
+	if err != nil {
+		t.Fatalf("open for append: %v", err)
+	}
+	_, err = f.WriteString(`{"role":"user","content":"orphan"}` + "\n")
+	if err != nil {
+		t.Fatalf("write orphan: %v", err)
+	}
+	f.Close()
+
+	// TruncateHistory(keepLast=4) should keep the last 4 of 11 lines,
+	// not the last 4 of 10.
+	err = store.TruncateHistory(ctx, "stale", 4)
+	if err != nil {
+		t.Fatalf("TruncateHistory: %v", err)
+	}
+
+	history, err := store.GetHistory(ctx, "stale")
+	if err != nil {
+		t.Fatalf("GetHistory: %v", err)
+	}
+	if len(history) != 4 {
+		t.Fatalf("expected 4, got %d", len(history))
+	}
+	// Last 4 of [a,b,c,d,e,f,g,h,i,j,orphan] = [h,i,j,orphan]
+	if history[0].Content != "h" {
+		t.Errorf("first kept = %q, want 'h'", history[0].Content)
+	}
+	if history[3].Content != "orphan" {
+		t.Errorf("last kept = %q, want 'orphan'", history[3].Content)
+	}
+}
+
 func TestCrashRecovery_PartialLine(t *testing.T) {
 	store := newTestStore(t)
 	ctx := context.Background()