diff --git a/internal/assets/mdl/mdl.go b/internal/assets/mdl/mdl.go
new file mode 100644
index 0000000..119440e
--- /dev/null
+++ b/internal/assets/mdl/mdl.go
@@ -0,0 +1,218 @@
+// Package mdl ports the ASCII MDL model-name checks from sow-assets-manifest's
+// mdl-name-lib.sh + mdl-scan.awk to pure Go. Binary (compiled) MDLs are opaque
+// here; the NWN engine is the validator for those. Detection mirrors
+// mdl-scan.awk exactly so behavior does not drift while that awk still runs in
+// sow-assets-manifest.
+package mdl
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// Mismatch is one model-name problem. Line is 1-based; 0 means the geometry
+// base-node mismatch, which the source has no single line for.
+type Mismatch struct {
+	Line int
+	What string
+	Got  string
+}
+
+// ExpectedName is the file stem with a trailing ".mdl" (any case) removed.
+func ExpectedName(path string) string {
+	base := filepath.Base(path)
+	if len(base) >= 4 && strings.EqualFold(base[len(base)-4:], ".mdl") {
+		return base[:len(base)-4]
+	}
+	return base
+}
+
+// ExpectedNameStem is an alias of ExpectedName kept for call-site clarity where
+// the value is used as the engine's model stem argument.
+func ExpectedNameStem(path string) string { return ExpectedName(path) }
+
+// IsASCII reports whether path is an uncompiled ASCII model: no NUL in the
+// first 256 bytes, and a leading keyword of '#' / newmodel / node /
+// setsupermodel. Mirrors mdl_is_ascii.
+func IsASCII(path string) (bool, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return false, err
+	}
+	return isASCII(data), nil
+}
+
+func isASCII(data []byte) bool {
+	head := data
+	if len(head) > 256 {
+		head = head[:256]
+	}
+	if bytes.IndexByte(head, 0) >= 0 {
+		return false
+	}
+	line := head
+	if i := bytes.IndexByte(line, '\n'); i >= 0 {
+		line = line[:i]
+	}
+	trimmed := strings.TrimLeft(string(line), " \t\r")
+	if strings.HasPrefix(trimmed, "#") {
+		return true
+	}
+	fields := strings.Fields(trimmed)
+	if len(fields) == 0 {
+		return false
+	}
+	tok := strings.ToLower(fields[0])
+	return strings.HasPrefix(tok, "newmodel") ||
+		strings.HasPrefix(tok, "node") ||
+		strings.HasPrefix(tok, "setsupermodel")
+}
+
+// lineFields splits a line into whitespace-delimited tokens with the trailing
+// CR removed, matching awk's default field split + \r strip.
+func lineFields(line string) []string {
+	return strings.Fields(strings.TrimRight(line, "\r"))
+}
+
+// field returns the 1-based nth field or "" if absent.
+func field(f []string, n int) string {
+	if n >= 1 && n <= len(f) {
+		return f[n-1]
+	}
+	return ""
+}
+
+// CheckNames returns every model-name mismatch in an ASCII model. Returns nil
+// for a binary model or one with no newmodel line (not a real model).
+func CheckNames(path string) ([]Mismatch, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	if !isASCII(data) {
+		return nil, nil
+	}
+	return checkNames(data, ExpectedName(path)), nil
+}
+
+func checkNames(data []byte, expected string) []Mismatch {
+	expLower := strings.ToLower(expected)
+	var out []Mismatch
+	seenModel := false
+	inGeom := false
+	curNode := ""
+	base := ""
+	baseFound := false
+
+	// header records one header-token mismatch (field n, 1-based) if the token
+	// is present and differs case-insensitively from the stem.
+	lines := strings.Split(string(data), "\n")
+	for i, raw := range lines {
+		f := lineFields(raw)
+		if len(f) == 0 {
+			continue
+		}
+		key := strings.ToLower(f[0])
+		mis := func(what string, n int) {
+			got := field(f, n)
+			if got != "" && !strings.EqualFold(got, expected) {
+				out = append(out, Mismatch{Line: i + 1, What: what, Got: got})
+			}
+		}
+		switch key {
+		case "newmodel":
+			seenModel = true
+			mis("newmodel", 2)
+		case "setsupermodel":
+			mis("setsupermodel model", 2)
+		case "beginmodelgeom":
+			inGeom = true
+			mis("beginmodelgeom", 2)
+		case "endmodelgeom":
+			inGeom = false
+			mis("endmodelgeom", 2)
+		case "donemodel":
+			mis("donemodel", 2)
+		case "newanim":
+			mis("newanim model", 3)
+		case "doneanim":
+			mis("doneanim model", 3)
+		case "node":
+			if inGeom {
+				curNode = field(f, 3)
+			}
+		case "parent":
+			if inGeom && !baseFound && strings.EqualFold(field(f, 2), "null") {
+				base = curNode
+				baseFound = true
+			}
+		}
+	}
+	if !seenModel {
+		return nil
+	}
+	if baseFound && base != "" && !strings.EqualFold(base, expLower) {
+		out = append(out, Mismatch{Line: 0, What: "root node", Got: base})
+	}
+	return out
+}
+
+// FixNames rewrites only the model identity to expected: the header tokens plus
+// the geometry base node's declaration / any parent / animroot pointing at the
+// old base name. Animation bone names and supermodel animroots are left alone
+// so inheritance keeps working. Mirrors mdl_fix_model_name in intent.
+//
+// ponytail: a rewritten line is rebuilt joining fields with single spaces and
+// drops a trailing CR, exactly like the awk it replaces; unchanged lines are
+// byte-identical. The engine ignores identity-line whitespace, and FixNames'
+// contract is only "produces a model that passes CheckNames", not byte parity.
+func FixNames(in []byte, expected string) (out []byte, changed bool) {
+	if !isASCII(in) {
+		return in, false
+	}
+	// oldbase: the base-node name to rename, only if it differs from expected.
+	oldbase := ""
+	for _, m := range checkNames(in, expected) {
+		if m.What == "root node" {
+			oldbase = m.Got
+		}
+	}
+
+	lines := strings.Split(string(in), "\n")
+	for idx, raw := range lines {
+		f := lineFields(raw)
+		if len(f) == 0 {
+			continue
+		}
+		key := strings.ToLower(f[0])
+		set := func(n int) bool {
+			if field(f, n) == "" {
+				return false
+			}
+			f[n-1] = expected
+			return true
+		}
+		modified := false
+		switch key {
+		case "newmodel", "setsupermodel", "beginmodelgeom", "endmodelgeom", "donemodel":
+			modified = set(2)
+		case "newanim", "doneanim":
+			modified = set(3)
+		case "node":
+			if oldbase != "" && strings.EqualFold(field(f, 3), oldbase) {
+				modified = set(3)
+			}
+		case "parent", "animroot":
+			if oldbase != "" && strings.EqualFold(field(f, 2), oldbase) {
+				modified = set(2)
+			}
+		}
+		if modified {
+			lines[idx] = strings.Join(f, " ")
+		}
+	}
+	out = []byte(strings.Join(lines, "\n"))
+	return out, !bytes.Equal(out, in)
+}
diff --git a/internal/assets/mdl/mdl_test.go b/internal/assets/mdl/mdl_test.go
new file mode 100644
index 0000000..6fc0dee
--- /dev/null
+++ b/internal/assets/mdl/mdl_test.go
@@ -0,0 +1,114 @@
+package mdl
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func writeMDL(t *testing.T, name, body string) string {
+	t.Helper()
+	p := filepath.Join(t.TempDir(), name)
+	if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	return p
+}
+
+func TestIsASCII(t *testing.T) {
+	ascii := writeMDL(t, "foo.mdl", "newmodel foo\nbeginmodelgeom foo\n")
+	if ok, err := IsASCII(ascii); err != nil || !ok {
+		t.Fatalf("ascii: ok=%v err=%v, want true nil", ok, err)
+	}
+	bin := writeMDL(t, "bar.mdl", "\x00\x01binary\x00garbage")
+	if ok, err := IsASCII(bin); err != nil || ok {
+		t.Fatalf("binary: ok=%v err=%v, want false nil", ok, err)
+	}
+	hash := writeMDL(t, "baz.mdl", "# a comment\nnewmodel baz\n")
+	if ok, _ := IsASCII(hash); !ok {
+		t.Fatal("leading # should be ascii")
+	}
+}
+
+func TestExpectedName(t *testing.T) {
+	for in, want := range map[string]string{
+		"a/b/Foo.MDL":     "Foo",
+		"waxbt_b_091.mdl": "waxbt_b_091",
+		"x.mdl":           "x",
+	} {
+		if got := ExpectedName(in); got != want {
+			t.Errorf("ExpectedName(%q)=%q want %q", in, got, want)
+		}
+	}
+}
+
+func TestCheckNames(t *testing.T) {
+	// Header token mismatch + base-node mismatch in one file.
+	body := "newmodel wrong\n" +
+		"setsupermodel wrong a_base\n" +
+		"beginmodelgeom foo\n" +
+		"  node dummy Wmgst_m_081\n" +
+		"    parent null\n" +
+		"  endnode\n" +
+		"endmodelgeom foo\n" +
+		"donemodel foo\n"
+	p := writeMDL(t, "foo.mdl", body)
+	got, err := CheckNames(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Expected stem "foo": newmodel(wrong), setsupermodel(wrong), base node(Wmgst_m_081).
+	if len(got) != 3 {
+		t.Fatalf("got %d mismatches, want 3: %+v", len(got), got)
+	}
+	if got[0].What != "newmodel" || got[0].Got != "wrong" || got[0].Line != 1 {
+		t.Errorf("first mismatch = %+v", got[0])
+	}
+	base := got[len(got)-1]
+	if base.What != "root node" || base.Got != "Wmgst_m_081" || base.Line != 0 {
+		t.Errorf("base mismatch = %+v", base)
+	}
+
+	// Clean model -> no mismatches.
+	clean := writeMDL(t, "bar.mdl",
+		"newmodel bar\nbeginmodelgeom bar\n  node dummy bar\n    parent null\n  endnode\nendmodelgeom bar\ndonemodel bar\n")
+	if got, _ := CheckNames(clean); len(got) != 0 {
+		t.Fatalf("clean model reported mismatches: %+v", got)
+	}
+
+	// Binary model -> nil, no error.
+	bin := writeMDL(t, "b.mdl", "\x00\x00binary")
+	if got, _ := CheckNames(bin); got != nil {
+		t.Fatalf("binary reported mismatches: %+v", got)
+	}
+}
+
+func TestFixNamesRoundTrips(t *testing.T) {
+	body := "newmodel wrong\n" +
+		"setsupermodel wrong\n" +
+		"beginmodelgeom wrong\n" +
+		"  node dummy Wmgst_m_081\n" +
+		"    parent null\n" +
+		"  endnode\n" +
+		"endmodelgeom wrong\n" +
+		"donemodel wrong\n"
+	out, changed := FixNames([]byte(body), "foo")
+	if !changed {
+		t.Fatal("expected changed=true")
+	}
+	p := filepath.Join(t.TempDir(), "foo.mdl")
+	if err := os.WriteFile(p, out, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	got, err := CheckNames(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 0 {
+		t.Fatalf("fixed model still has mismatches: %+v\n%s", got, out)
+	}
+	// Idempotent: fixing a clean model changes nothing.
+	if _, changed := FixNames(out, "foo"); changed {
+		t.Fatal("second fix reported a change")
+	}
+}