diff --git a/README.md b/README.md
index 7e30de0..44d3eda 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,8 @@ CSV++ extends traditional CSV to support **arrays** and **structured fields** wi
 
 ## Requirements
 
-- Go 1.24 or later
+- Go 1.25 or later
+- `GOEXPERIMENT=jsonv2` environment variable (required by `csvpputil` package, which uses `encoding/json/jsontext`)
 
 ## Installation
 
@@ -29,6 +30,13 @@ CSV++ extends traditional CSV to support **arrays** and **structured fields** wi
 go get github.com/osamingo/go-csvpp
 ```
 
+When building or testing packages that depend on `csvpputil`, set the experiment flag:
+
+```bash
+GOEXPERIMENT=jsonv2 go build ./...
+GOEXPERIMENT=jsonv2 go test ./...
+```
+
 ## Quick Start
 
 ### Reading CSV++ Data
@@ -234,29 +242,17 @@ writer.Flush()              // Flush buffer
 ### Marshal/Unmarshal
 
 ```go
-// Unmarshal CSV++ data into structs
+// Unmarshal CSV++ data into structs (r is io.Reader)
 var people []Person
-err := csvpp.Unmarshal(reader, &people)
+err := csvpp.Unmarshal(r, &people)
 
-// Marshal structs to CSV++ data
-err := csvpp.Marshal(writer, people)
+// Marshal structs to CSV++ data (w is io.Writer)
+err := csvpp.Marshal(w, people)
 ```
 
 ### Struct Tags
 
-Use `csvpp` struct tags to map fields:
-
-```go
-type Record struct {
-    Name     string   `csvpp:"name"`           // Simple field
-    Tags     []string `csvpp:"tags[]"`         // Array field
-    Location struct {                          // Structured field
-        Lat string
-        Lon string
-    } `csvpp:"geo(lat^lon)"`
-    Addresses []Address `csvpp:"addr[](street^city)"` // Array structured
-}
-```
+See [Struct Mapping](#struct-mapping) above for tag syntax and usage.
 
 ## JSON/YAML Conversion (csvpputil)
 
diff --git a/cmd/csvpp/README.md b/cmd/csvpp/README.md
index eeb7aac..146af2a 100644
--- a/cmd/csvpp/README.md
+++ b/cmd/csvpp/README.md
@@ -5,15 +5,17 @@ A command-line tool for working with CSV++ files.
 ## Installation
 
 ```bash
-go install github.com/osamingo/go-csvpp/cmd/csvpp@latest
+GOEXPERIMENT=jsonv2 go install github.com/osamingo/go-csvpp/cmd/csvpp@latest
 ```
 
 Or build from source:
 
 ```bash
-go build -o csvpp ./cmd/csvpp
+GOEXPERIMENT=jsonv2 go build -o csvpp ./cmd/csvpp
 ```
 
+> **Note:** `GOEXPERIMENT=jsonv2` is required because this tool depends on `encoding/json/jsontext` (Go 1.25+).
+
 ## Commands
 
 ### validate
@@ -82,9 +84,15 @@ cat input.csvpp | csvpp view
 | `↑` / `↓` | Navigate rows |
 | `Space` | Toggle row selection |
 | `y` / `c` | Copy header + selected rows to clipboard (CSV++ format) |
-| `Esc` | Clear selection |
+| `/` | Open filter input |
+| `Enter` | Apply filter (in filter mode) |
+| `Esc` | Cancel filter / Clear active filter / Clear selection |
 | `q` / `Ctrl+C` | Quit |
 
+**Filter syntax:**
+- Type text to search all columns (e.g., `Alice`)
+- Use `column:value` to search a specific column (e.g., `name:Alice`)
+
 **Note:** When stdin is not a TTY (e.g., in a pipe), a plain text table is displayed instead of the interactive TUI.
 
 ## Examples
diff --git a/csvpputil/README.md b/csvpputil/README.md
index 3026ff4..5b91c8d 100644
--- a/csvpputil/README.md
+++ b/csvpputil/README.md
@@ -42,7 +42,9 @@ if err := w.Close(); err != nil {
 #### YAMLArrayWriter
 
 ```go
-w := csvpputil.NewYAMLArrayWriter(os.Stdout, headers)
+w := csvpputil.NewYAMLArrayWriter(os.Stdout, headers,
+    csvpputil.WithYAMLCapacity(1000), // optional: pre-allocate buffer
+)
 
 for _, record := range records {
     if err := w.Write(record); err != nil {
@@ -55,6 +57,9 @@ if err := w.Close(); err != nil {
 }
 ```
 
+**Options:**
+- `WithYAMLCapacity(n)` - Pre-allocates the internal buffer for `n` records, reducing memory allocations when the approximate record count is known.
+
 **Note:** YAML output is buffered until `Close()` due to go-yaml library constraints.
 
 ### Convenience Functions
diff --git a/export_test.go b/export_test.go
index cdcdbbc..4368764 100644
--- a/export_test.go
+++ b/export_test.go
@@ -15,3 +15,8 @@ var (
 	ExtractTagName                = extractTagName
 	CachedTypeInfo                = cachedTypeInfo
 )
+
+// ReaderLine returns the current line number of the reader for testing.
+func ReaderLine(r *Reader) int {
+	return r.line
+}
diff --git a/reader.go b/reader.go
index 3f524cc..c6de9ce 100644
--- a/reader.go
+++ b/reader.go
@@ -85,6 +85,7 @@ func (r *Reader) ReadAll() ([][]*Field, error) {
 
 	result := make([][]*Field, 0, len(records))
 	for _, record := range records {
+		r.line++
 		fields, err := r.parseRecord(record)
 		if err != nil {
 			return nil, err
diff --git a/reader_test.go b/reader_test.go
index 4a41017..3ab2dad 100644
--- a/reader_test.go
+++ b/reader_test.go
@@ -576,6 +576,23 @@ func TestReader_ComponentsMoreThanHeaders(t *testing.T) {
 	}
 }
 
+func TestReader_ReadAll_LineTracking(t *testing.T) {
+	t.Parallel()
+
+	input := "name,age\nAlice,30\nBob,25\nCharlie,35\n"
+	r := csvpp.NewReader(strings.NewReader(input))
+
+	_, err := r.ReadAll()
+	if err != nil {
+		t.Fatalf("Reader.ReadAll() error = %v", err)
+	}
+
+	// After reading header (line 1) + 3 data records, line should be 4.
+	if got := csvpp.ReaderLine(r); got != 4 {
+		t.Errorf("Reader.ReadAll() line = %d, want 4", got)
+	}
+}
+
 func TestReader_ArrayStructuredInComponents(t *testing.T) {
 	t.Parallel()
 
diff --git a/writer.go b/writer.go
index bae7eba..31028f5 100644
--- a/writer.go
+++ b/writer.go
@@ -162,6 +162,9 @@ func formatComponentList(components []*ColumnHeader, delim rune) string {
 
 // formatField converts a Field to a string.
 func (w *Writer) formatField(header *ColumnHeader, field *Field) string {
+	if field == nil {
+		return ""
+	}
 	if header == nil {
 		return field.Value
 	}
diff --git a/writer_test.go b/writer_test.go
index 50d9ae0..6e60b74 100644
--- a/writer_test.go
+++ b/writer_test.go
@@ -506,6 +506,35 @@ func TestWriter_NoHeaderForRecord(t *testing.T) {
 	}
 }
 
+func TestWriter_Write_NilField(t *testing.T) {
+	t.Parallel()
+
+	headers := []*csvpp.ColumnHeader{
+		{Name: "name", Kind: csvpp.SimpleField},
+		{Name: "age", Kind: csvpp.SimpleField},
+	}
+	record := []*csvpp.Field{
+		{Value: "Alice"},
+		nil, // nil field should not panic
+	}
+
+	var buf bytes.Buffer
+	w := csvpp.NewWriter(&buf)
+	w.SetHeaders(headers)
+
+	err := w.Write(record)
+	if err != nil {
+		t.Fatalf("Writer.Write() error = %v", err)
+	}
+
+	w.Flush()
+	want := "Alice,\n"
+	got := buf.String()
+	if diff := cmp.Diff(want, got); diff != "" {
+		t.Errorf("Writer.Write() mismatch (-want +got):\n%s", diff)
+	}
+}
+
 func TestFormatComponentList(t *testing.T) {
 	t.Parallel()