fix: parse skill frontmatter as YAML (#25610)

codersdk/workspacesdk/frontmatter.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"golang.org/x/xerrors"
+	"gopkg.in/yaml.v3"
 )
 
 // SkillNameRegex is the regular expression used to validate kebab-case skill names.
@@ -24,32 +25,21 @@ var markdownCommentRe = regexp.MustCompile(`<!--[\s\S]*?-->`)
 // the frontmatter is missing a required name field.
 var ErrFrontmatterNameRequired = xerrors.New("frontmatter missing required 'name' field")
 
-func unquoteFrontmatterScalar(value string) string {
-	if len(value) < 2 {
-		return value
+func frontmatterStringField(frontmatter map[string]any, key string) (string, bool, error) {
+	value, ok := frontmatter[key]
+	if !ok {
+		return "", false, nil
 	}
-
-	quote := value[0]
-	if quote != value[len(value)-1] {
-		return value
-	}
-
-	inner := value[1 : len(value)-1]
-	switch quote {
-	case '"':
-		// This parser supports a small SKILL.md scalar subset, not full
-		// YAML. Double quotes only unescape quoted text and Windows paths.
-		return strings.NewReplacer(`\"`, `"`, `\\`, `\`).Replace(inner)
-	case '\'':
-		return inner
-	default:
-		return value
+	stringValue, ok := value.(string)
+	if !ok {
+		return "", true, xerrors.Errorf("frontmatter field %q must be a string", key)
 	}
+	return strings.TrimRight(stringValue, "\r\n"), true, nil
 }
 
 // ParseSkillFrontmatter extracts name, description, and the
 // remaining body from a skill meta file. The expected format is
-// YAML-ish frontmatter delimited by "---" lines:
+// YAML frontmatter delimited by "---" lines:
 //
 //	---
 //	name: my-skill
@@ -78,25 +68,23 @@ func ParseSkillFrontmatter(content string) (name, description, body string, err
 		)
 	}
 
-	for _, line := range lines[1:closingIdx] {
-		key, value, ok := strings.Cut(line, ":")
-		if !ok {
-			continue
-		}
-		key = strings.TrimSpace(key)
-		value = strings.TrimSpace(value)
-		value = unquoteFrontmatterScalar(value)
-		switch strings.ToLower(key) {
-		case "name":
-			name = value
-		case "description":
-			description = value
-		}
+	frontmatterContent := strings.Join(lines[1:closingIdx], "\n")
+	var frontmatter map[string]any
+	if err := yaml.Unmarshal([]byte(frontmatterContent), &frontmatter); err != nil {
+		return "", "", "", xerrors.Errorf("parse frontmatter YAML: %w", err)
 	}
 
-	if name == "" {
+	name, ok, err := frontmatterStringField(frontmatter, "name")
+	if err != nil {
+		return "", "", "", xerrors.Errorf("%w: %v", ErrFrontmatterNameRequired, err)
+	}
+	if !ok || name == "" {
 		return "", "", "", xerrors.Errorf("%w", ErrFrontmatterNameRequired)
 	}
+	description, _, err = frontmatterStringField(frontmatter, "description")
+	if err != nil {
+		return "", "", "", err
+	}
 
 	// Everything after the closing delimiter is the body.
 	body = strings.Join(lines[closingIdx+1:], "\n")

codersdk/workspacesdk/frontmatter_test.go

@@ -1,6 +1,7 @@
 package workspacesdk_test
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -41,13 +42,48 @@ func TestParseSkillFrontmatter(t *testing.T) {
 		require.Equal(t, "Review \"critical\" C:\\paths.", desc)
 	})
 
-	t.Run("PlainHashValue", func(t *testing.T) {
+	t.Run("FoldedDescription", func(t *testing.T) {
+		t.Parallel()
+		name, desc, body, err := workspacesdk.ParseSkillFrontmatter(
+			strings.Join([]string{
+				"---",
+				"name: brainstorming",
+				"description: >",
+				"  Use before any creative work: features, components, functionality changes,",
+				"  or behavior modifications. Turns ideas into approved designs through",
+				"  collaborative dialog. Hard gate: no implementation action until the",
+				"  design is presented and approved.",
+				"",
+				"---",
+				"Use this skill.",
+			}, "\n"),
+		)
+		require.NoError(t, err)
+		require.Equal(t, "brainstorming", name)
+		require.Equal(t, strings.Join([]string{
+			"Use before any creative work: features, components, functionality changes,",
+			"or behavior modifications. Turns ideas into approved designs through",
+			"collaborative dialog. Hard gate: no implementation action until the",
+			"design is presented and approved.",
+		}, " "), desc)
+		require.Equal(t, "Use this skill.", body)
+	})
+
+	t.Run("YAMLComments", func(t *testing.T) {
 		t.Parallel()
 		_, desc, _, err := workspacesdk.ParseSkillFrontmatter(
 			"---\nname: plain-hash\ndescription: Build # test\n---\nBody\n",
 		)
 		require.NoError(t, err)
-		require.Equal(t, "Build # test", desc)
+		require.Equal(t, "Build", desc)
+	})
+
+	t.Run("ErrorNullDescription", func(t *testing.T) {
+		t.Parallel()
+		_, _, _, err := workspacesdk.ParseSkillFrontmatter(
+			"---\nname: null-description\ndescription: null\n---\nBody\n",
+		)
+		require.ErrorContains(t, err, `frontmatter field "description" must be a string`)
 	})
 
 	t.Run("NoDescription", func(t *testing.T) {
@@ -99,14 +135,12 @@ func TestParseSkillFrontmatter(t *testing.T) {
 		require.Empty(t, body)
 	})
 
-	t.Run("CaseInsensitiveKeys", func(t *testing.T) {
+	t.Run("YAMLKeysAreCaseSensitive", func(t *testing.T) {
 		t.Parallel()
-		name, desc, _, err := workspacesdk.ParseSkillFrontmatter(
+		_, _, _, err := workspacesdk.ParseSkillFrontmatter(
 			"---\nName: upper\nDescription: Also upper\n---\n",
 		)
-		require.NoError(t, err)
-		require.Equal(t, "upper", name)
-		require.Equal(t, "Also upper", desc)
+		require.ErrorIs(t, err, workspacesdk.ErrFrontmatterNameRequired)
 	})
 
 	t.Run("UnknownKeysIgnored", func(t *testing.T) {
@@ -139,6 +173,15 @@ func TestParseSkillFrontmatter(t *testing.T) {
 		require.ErrorContains(t, err, "frontmatter missing required 'name' field")
 	})
 
+	t.Run("ErrorNullName", func(t *testing.T) {
+		t.Parallel()
+		_, _, _, err := workspacesdk.ParseSkillFrontmatter(
+			"---\nname: null\n---\nBody\n",
+		)
+		require.ErrorIs(t, err, workspacesdk.ErrFrontmatterNameRequired)
+		require.ErrorContains(t, err, `frontmatter field "name" must be a string`)
+	})
+
 	t.Run("WhitespaceAroundDelimiters", func(t *testing.T) {
 		t.Parallel()
 		name, _, _, err := workspacesdk.ParseSkillFrontmatter(