diff --git a/cmd/cue/cmd/common.go b/cmd/cue/cmd/common.go
index 302e7e2f1a8..f361704aafc 100644
--- a/cmd/cue/cmd/common.go
+++ b/cmd/cue/cmd/common.go
@@ -36,7 +36,6 @@ import (
 	"cuelang.org/go/internal/core/adt"
 	"cuelang.org/go/internal/encoding"
 	"cuelang.org/go/internal/filetypes"
-	"cuelang.org/go/internal/value"
 )
 
 var requestedVersion = os.Getenv("CUE_SYNTAX_OVERRIDE")
@@ -810,10 +809,11 @@ func buildTools(cmd *Command, args []string) (*cue.Instance, error) {
 		inst = cue.Merge(insts...)
 	}
 
-	r := value.ConvertToRuntime(inst.Value().Context())
+	ctx := inst.Value().Context()
 	for _, b := range binst {
 		for _, i := range b.Imports {
-			if _, err := r.Build(i); err != nil {
+			val := ctx.BuildInstance(i)
+			if err := val.Err(); err != nil {
 				return nil, err
 			}
 		}
diff --git a/cmd/cue/cmd/flags.go b/cmd/cue/cmd/flags.go
index 0e9e1c4cfab..91d5db73f8e 100644
--- a/cmd/cue/cmd/flags.go
+++ b/cmd/cue/cmd/flags.go
@@ -116,11 +116,6 @@ func addInjectionFlags(f *pflag.FlagSet, auto, hidden bool) {
 
 type flagName string
 
-type unaddedFlagUse struct {
-	cmd  string
-	flag flagName
-}
-
 // ensureAdded detects if a flag is being used without it first being
 // added to the flagSet. Because flagNames are global, it is quite
 // easy to accidentally use a flag in a command without adding it to
diff --git a/cmd/cue/cmd/get_go.go b/cmd/cue/cmd/get_go.go
index 9675ede0731..bee1b62fd8b 100644
--- a/cmd/cue/cmd/get_go.go
+++ b/cmd/cue/cmd/get_go.go
@@ -301,7 +301,9 @@ func typeSignature(params, results []types.Type) *types.Signature {
 	for i, result := range results {
 		resultVars[i] = types.NewParam(token.NoPos, nil, "", result)
 	}
-	return types.NewSignature(
+	return types.NewSignatureType(
+		nil,
+		nil,
 		nil,
 		types.NewTuple(paramVars...),
 		types.NewTuple(resultVars...),
diff --git a/encoding/gocode/generator.go b/encoding/gocode/generator.go
index 6c4e8befd1a..59e63d1e926 100644
--- a/encoding/gocode/generator.go
+++ b/encoding/gocode/generator.go
@@ -27,7 +27,6 @@ import (
 
 	"cuelang.org/go/cue"
 	"cuelang.org/go/cue/errors"
-	"cuelang.org/go/internal/value"
 )
 
 // Config defines options for generation Go code.
@@ -154,7 +153,7 @@ func Generate(pkgPath string, inst cue.InstanceOrValue, c *Config) (b []byte, er
 		g.decl(iter.Label(), iter.Value())
 	}
 
-	r := value.ConvertToRuntime(val.Context())
+	r := (*cue.Runtime)(val.Context())
 	b, err = r.Marshal(&val)
 	g.addErr(err)
 
diff --git a/encoding/gocode/gocodec/codec.go b/encoding/gocode/gocodec/codec.go
index b40223c9940..d5b4e5809eb 100644
--- a/encoding/gocode/gocodec/codec.go
+++ b/encoding/gocode/gocodec/codec.go
@@ -95,7 +95,7 @@ func (c *Codec) Encode(v cue.Value, x interface{}) error {
 	return v.Decode(x)
 }
 
-var defaultCodec = New(value.ConvertToRuntime(cuecontext.New()), nil)
+var defaultCodec = New(cuecontext.New(), nil)
 
 // Validate calls Validate on a default Codec for the type of x.
 func Validate(x interface{}) error {
diff --git a/internal/ci/checks/commit.go b/internal/ci/checks/commit.go
index 86c5b963d2c..3221a017ccf 100644
--- a/internal/ci/checks/commit.go
+++ b/internal/ci/checks/commit.go
@@ -51,7 +51,7 @@ func checkCommit(dir string) error {
 	// line because each commit must be signed-off.
 	lines := strings.Split(body, "\n")
 	if len(lines) > 1 && lines[1] != "" {
-		return fmt.Errorf("The second line of a commit message must be blank")
+		return fmt.Errorf("the second line of a commit message must be blank")
 	}
 
 	// All authors, including co-authors, must have a signed-off trailer by email.
diff --git a/internal/envflag/flag.go b/internal/envflag/flag.go
index 4c640ffafd2..085aa7c8c38 100644
--- a/internal/envflag/flag.go
+++ b/internal/envflag/flag.go
@@ -67,7 +67,7 @@ func Parse[T any](flags *T, env string) error {
 			v, err := strconv.ParseBool(valueStr)
 			if err != nil {
 				// Invalid format, return an error immediately.
-				return invalidError{
+				return errInvalid{
 					fmt.Errorf("invalid bool value for %s: %v", name, err),
 				}
 			}
@@ -85,11 +85,11 @@ func Parse[T any](flags *T, env string) error {
 	return errors.Join(errs...)
 }
 
-// An InvalidError indicates a malformed input string.
-var InvalidError = errors.New("invalid value")
+// An ErrInvalid indicates a malformed input string.
+var ErrInvalid = errors.New("invalid value")
 
-type invalidError struct{ error }
+type errInvalid struct{ error }
 
-func (invalidError) Is(err error) bool {
-	return err == InvalidError
+func (errInvalid) Is(err error) bool {
+	return err == ErrInvalid
 }
diff --git a/internal/envflag/flag_test.go b/internal/envflag/flag_test.go
index 378a980a086..07d4ac3e1ae 100644
--- a/internal/envflag/flag_test.go
+++ b/internal/envflag/flag_test.go
@@ -36,7 +36,7 @@ func invalid[T comparable](want T) func(t *testing.T) {
 	return func(t *testing.T) {
 		var x T
 		err := Init(&x, "TEST_VAR")
-		qt.Assert(t, qt.ErrorIs(err, InvalidError))
+		qt.Assert(t, qt.ErrorIs(err, ErrInvalid))
 		qt.Assert(t, qt.Equals(x, want))
 	}
 }
diff --git a/internal/pkg/types.go b/internal/pkg/types.go
index e3422c38c5b..e7e3bfb6254 100644
--- a/internal/pkg/types.go
+++ b/internal/pkg/types.go
@@ -74,10 +74,7 @@ func (s *Struct) IsOpen() bool {
 	}
 	// The equivalent code for the old implementation.
 	ot := s.node.OptionalTypes()
-	if ot&^adt.HasDynamic != 0 {
-		return true
-	}
-	return false
+	return ot&^adt.HasDynamic != 0
 }
 
 // A ValidationError indicates an error that is only valid if a builtin is used
diff --git a/internal/value/value.go b/internal/value/value.go
index 7f5e0bf627d..65c1b14345e 100644
--- a/internal/value/value.go
+++ b/internal/value/value.go
@@ -27,10 +27,6 @@ import (
 	"cuelang.org/go/internal/types"
 )
 
-func ConvertToRuntime(c *cue.Context) *cue.Runtime {
-	return (*cue.Runtime)(c)
-}
-
 func ConvertToContext[Ctx *cue.Runtime | *cue.Context](ctx Ctx) *cue.Context {
 	if ctx, ok := any(ctx).(*cue.Runtime); ok {
 		(*runtime.Runtime)(ctx).Init()