internal/pkg: optionally named static file

These are generally for generating configuration files or build scripts, naming them is quite useful.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/file.go

@@ -3,6 +3,7 @@ package pkg
 import (
 	"context"
 	"crypto/sha512"
+	"fmt"
 )
 
 // A fileArtifact is an [Artifact] that cures into data known ahead of time.
@@ -10,10 +11,28 @@ type fileArtifact []byte
 
 var _ KnownChecksum = fileArtifact{}
 
+// fileArtifactNamed embeds fileArtifact alongside a caller-supplied name.
+type fileArtifactNamed struct {
+	fileArtifact
+	// Caller-supplied user-facing reporting name.
+	name string
+}
+
+var _ fmt.Stringer = fileArtifactNamed{}
+
+// String returns the caller-supplied reporting name.
+func (a fileArtifactNamed) String() string { return a.name }
+
 // NewFile returns a [File] that cures into a caller-supplied byte slice.
 //
-// Caller must not modify data after NewBin returns.
-func NewFile(data []byte) File { return fileArtifact(data) }
+// Caller must not modify data after NewFile returns.
+func NewFile(name string, data []byte) File {
+	f := fileArtifact(data)
+	if name != "" {
+		return fileArtifactNamed{f, name}
+	}
+	return f
+}
 
 // Kind returns the hardcoded [Kind] constant.
 func (a fileArtifact) Kind() Kind { return KindFile }