feat(theming): integrate NvChad chadrc rewrite into Apply

internal/modules/neovim/neovim.go

@@ -88,6 +88,44 @@ func (m Module) resolvedTheme() string {
 	return "gruvbox"
 }
 
+// WriteChadrc renders chadrc.lua for the given NvChad theme name and writes
+// it to ~/.config/nvim/lua/chadrc.lua. If the file does not already exist
+// and the surrounding nvim config dir does not exist, the function returns
+// nil without writing anything (the user hasn't installed neovim yet).
+//
+// Exported so the theming package can re-render chadrc on theme switches
+// without re-running the full Module pipeline.
+func WriteChadrc(nvChadThemeName string) error {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return err
+	}
+	cfg := filepath.Join(home, ".config", "nvim")
+	chadrcPath := filepath.Join(cfg, "lua", "chadrc.lua")
+
+	// If chadrc doesn't exist, only write when the parent dir exists. A
+	// fresh system where nvim was never installed should be a no-op.
+	if _, err := os.Stat(chadrcPath); err != nil {
+		if _, err := os.Stat(cfg); err != nil {
+			return nil
+		}
+	}
+
+	tmplBytes, err := assets.ReadFile("assets/chadrc.lua.tmpl")
+	if err != nil {
+		return err
+	}
+	tmpl, err := template.New("chadrc").Parse(string(tmplBytes))
+	if err != nil {
+		return err
+	}
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, struct{ NvChadTheme string }{NvChadTheme: nvChadThemeName}); err != nil {
+		return err
+	}
+	return platform.WriteUserFile(chadrcPath, buf.Bytes(), 0o644)
+}
+
 func (m Module) renderChadrc() ([]byte, error) {
 	tmplBytes, err := assets.ReadFile("assets/chadrc.lua.tmpl")
 	if err != nil {

internal/modules/neovim/neovim_test.go

@@ -177,4 +177,34 @@ func TestUnknownThemeFallsBackToFirst(t *testing.T) {
 	}
 }
 
+func TestWriteChadrcWritesFile(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	cfg := filepath.Join(home, ".config", "nvim")
+	if err := os.MkdirAll(cfg, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := WriteChadrc("dracula"); err != nil {
+		t.Fatal(err)
+	}
+	data, err := os.ReadFile(filepath.Join(cfg, "lua", "chadrc.lua"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(string(data), `theme = "dracula"`) {
+		t.Fatalf("theme not applied: %s", data)
+	}
+}
+
+func TestWriteChadrcNoopWithoutConfigDir(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	if err := WriteChadrc("gruvbox"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(home, ".config", "nvim", "lua", "chadrc.lua")); !os.IsNotExist(err) {
+		t.Fatal("chadrc should not be created on a bare system")
+	}
+}
+
 var _ module.Module = Module{}