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skillpackage/validate.go

@@ -0,0 +1,102 @@
+package skillpackage
+
+import (
+	"fmt"
+	"strings"
+	"unicode/utf8"
+
+	"gopkg.in/yaml.v3"
+)
+
+var agentSkillsSpecFrontMatterKeys = map[string]struct{}{
+	"name": {}, "description": {}, "license": {}, "compatibility": {},
+	"metadata": {}, "allowed-tools": {},
+}
+
+// ValidateAgentSkillManifest enforces Agent Skills rules for name and description.
+func ValidateAgentSkillManifest(m *SkillManifest) error {
+	if m == nil {
+		return fmt.Errorf("skill manifest is nil")
+	}
+	if strings.TrimSpace(m.Name) == "" {
+		return fmt.Errorf("SKILL.md front matter: name is required")
+	}
+	if strings.TrimSpace(m.Description) == "" {
+		return fmt.Errorf("SKILL.md front matter: description is required")
+	}
+	if utf8.RuneCountInString(m.Name) > 64 {
+		return fmt.Errorf("name exceeds 64 characters (Agent Skills limit)")
+	}
+	if utf8.RuneCountInString(m.Description) > 1024 {
+		return fmt.Errorf("description exceeds 1024 characters (Agent Skills limit)")
+	}
+	if m.Name != strings.ToLower(m.Name) {
+		return fmt.Errorf("name must be lowercase (Agent Skills)")
+	}
+	for _, r := range m.Name {
+		if !((r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-') {
+			return fmt.Errorf("name must contain only lowercase letters, numbers, hyphens (Agent Skills)")
+		}
+	}
+	if strings.HasPrefix(m.Name, "-") || strings.HasSuffix(m.Name, "-") {
+		return fmt.Errorf("name must not start or end with a hyphen (Agent Skills spec)")
+	}
+	if strings.Contains(m.Name, "--") {
+		return fmt.Errorf("name must not contain consecutive hyphens (Agent Skills spec)")
+	}
+	lname := strings.ToLower(m.Name)
+	if strings.Contains(lname, "anthropic") || strings.Contains(lname, "claude") {
+		return fmt.Errorf("name must not contain reserved words anthropic or claude")
+	}
+	return nil
+}
+
+// ValidateAgentSkillManifestInPackage checks manifest and that name matches package directory.
+func ValidateAgentSkillManifestInPackage(m *SkillManifest, packageDirName string) error {
+	if err := ValidateAgentSkillManifest(m); err != nil {
+		return err
+	}
+	if strings.TrimSpace(packageDirName) == "" {
+		return nil
+	}
+	if m.Name != packageDirName {
+		return fmt.Errorf("SKILL.md name %q must match directory name %q (Agent Skills spec)", m.Name, packageDirName)
+	}
+	return nil
+}
+
+// ValidateOfficialFrontMatterTopLevelKeys rejects keys not in the open spec.
+func ValidateOfficialFrontMatterTopLevelKeys(fmYAML string) error {
+	var top map[string]interface{}
+	if err := yaml.Unmarshal([]byte(fmYAML), &top); err != nil {
+		return fmt.Errorf("SKILL.md front matter: %w", err)
+	}
+	for k := range top {
+		if _, ok := agentSkillsSpecFrontMatterKeys[k]; !ok {
+			return fmt.Errorf("SKILL.md front matter: unsupported key %q (allowed: name, description, license, compatibility, metadata, allowed-tools — see https://agentskills.io/specification.md)", k)
+		}
+	}
+	return nil
+}
+
+// ValidateSkillMDPackage validates SKILL.md bytes for writes.
+func ValidateSkillMDPackage(raw []byte, packageDirName string) error {
+	fmYAML, body, err := ExtractSkillMDFrontMatterYAML(raw)
+	if err != nil {
+		return err
+	}
+	if err := ValidateOfficialFrontMatterTopLevelKeys(fmYAML); err != nil {
+		return err
+	}
+	if strings.TrimSpace(body) == "" {
+		return fmt.Errorf("SKILL.md: markdown body after front matter must not be empty")
+	}
+	var fm SkillManifest
+	if err := yaml.Unmarshal([]byte(fmYAML), &fm); err != nil {
+		return fmt.Errorf("SKILL.md front matter: %w", err)
+	}
+	if c := strings.TrimSpace(fm.Compatibility); c != "" && utf8.RuneCountInString(c) > 500 {
+		return fmt.Errorf("compatibility exceeds 500 characters (Agent Skills spec)")
+	}
+	return ValidateAgentSkillManifestInPackage(&fm, packageDirName)
+}