Consolidate artifact declarations

internal/artifact/artifact.go

@@ -0,0 +1,62 @@
+// Package artifact owns shared build artifact identity rules.
+package artifact
+
+import (
+	"fmt"
+	"strings"
+)
+
+const ManifestFilename = "SHA256SUMS"
+
+type Target struct {
+	OS   string
+	Arch string
+}
+
+type Declaration struct {
+	Target   Target
+	Filename string
+}
+
+// NormalizeTargets removes duplicate targets while preserving their first
+// occurrence.
+func NormalizeTargets(targets []Target) []Target {
+	seen := make(map[Target]struct{}, len(targets))
+	result := make([]Target, 0, len(targets))
+	for _, target := range targets {
+		if _, ok := seen[target]; ok {
+			continue
+		}
+		seen[target] = struct{}{}
+		result = append(result, target)
+	}
+	return result
+}
+
+// ValidComponent reports whether value is a nonempty filename component under
+// the build and receipt contracts.
+func ValidComponent(value string) bool {
+	return value != "" && !strings.ContainsAny(value, "/\\\r\n")
+}
+
+// Filename returns the declared binary filename for one target.
+func Filename(binaryName, version string, target Target) string {
+	filename := fmt.Sprintf("%s-%s-%s-%s", binaryName, version, target.OS, target.Arch)
+	if target.OS == "windows" {
+		filename += ".exe"
+	}
+	return filename
+}
+
+// ExpectedBuild returns artifact declarations in target order. Callers retain
+// responsibility for validating their boundary-specific build identity.
+func ExpectedBuild(binaryName, version string, targets []Target) []Declaration {
+	declarations := make([]Declaration, 0, len(targets))
+	for _, target := range targets {
+		declarations = append(declarations, Declaration{
+			Target:   target,
+			Filename: Filename(binaryName, version, target),
+		})
+	}
+	return declarations
+}