feat(extract): add Text() dispatcher with md/txt passthrough

ingestion/internal/extract/extract_test.go

@@ -0,0 +1,40 @@
+// ingestion/internal/extract/extract_test.go
+package extract
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestText_Markdown(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "note.md")
+	require.NoError(t, os.WriteFile(path, []byte("# Hello\n\nWorld."), 0o644))
+
+	got, err := Text(path)
+	require.NoError(t, err)
+	assert.Equal(t, "# Hello\n\nWorld.", got)
+}
+
+func TestText_Txt(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "note.txt")
+	require.NoError(t, os.WriteFile(path, []byte("plain text"), 0o644))
+
+	got, err := Text(path)
+	require.NoError(t, err)
+	assert.Equal(t, "plain text", got)
+}
+
+func TestText_UnsupportedExtension(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "data.csv")
+	require.NoError(t, os.WriteFile(path, []byte("a,b,c"), 0o644))
+
+	_, err := Text(path)
+	assert.ErrorContains(t, err, "unsupported")
+}