fix: Handle colons in skill description frontmatter (#16345)

Co-authored-by: gemini-code-assist[bot] <gemini-code-assist[bot]@users.noreply.github.com>

packages/core/src/skills/skillLoader.test.ts

@@ -100,4 +100,98 @@ describe('skillLoader', () => {
     expect(skills).toEqual([]);
     expect(coreEvents.emitFeedback).not.toHaveBeenCalled();
   });
+
+  it('should parse skill with colon in description (issue #16323)', async () => {
+    const skillDir = path.join(testRootDir, 'colon-skill');
+    await fs.mkdir(skillDir, { recursive: true });
+    const skillFile = path.join(skillDir, 'SKILL.md');
+    await fs.writeFile(
+      skillFile,
+      `---
+name: foo
+description: Simple story generation assistant for fiction writing. Use for creating characters, scenes, storylines, and prose. Trigger words: character, scene, storyline, story, prose, fiction, writing.
+---
+# Instructions
+Do something.
+`,
+    );
+
+    const skills = await loadSkillsFromDir(testRootDir);
+
+    expect(skills).toHaveLength(1);
+    expect(skills[0].name).toBe('foo');
+    expect(skills[0].description).toContain('Trigger words:');
+  });
+
+  it('should parse skill with multiple colons in description', async () => {
+    const skillDir = path.join(testRootDir, 'multi-colon-skill');
+    await fs.mkdir(skillDir, { recursive: true });
+    const skillFile = path.join(skillDir, 'SKILL.md');
+    await fs.writeFile(
+      skillFile,
+      `---
+name: multi-colon
+description: Use this for tasks like: coding, reviewing, testing. Keywords: async, await, promise.
+---
+# Instructions
+Do something.
+`,
+    );
+
+    const skills = await loadSkillsFromDir(testRootDir);
+
+    expect(skills).toHaveLength(1);
+    expect(skills[0].name).toBe('multi-colon');
+    expect(skills[0].description).toContain('tasks like:');
+    expect(skills[0].description).toContain('Keywords:');
+  });
+
+  it('should parse skill with quoted YAML description (backward compatibility)', async () => {
+    const skillDir = path.join(testRootDir, 'quoted-skill');
+    await fs.mkdir(skillDir, { recursive: true });
+    const skillFile = path.join(skillDir, 'SKILL.md');
+    await fs.writeFile(
+      skillFile,
+      `---
+name: quoted-skill
+description: "A skill with colons: like this one: and another."
+---
+# Instructions
+Do something.
+`,
+    );
+
+    const skills = await loadSkillsFromDir(testRootDir);
+
+    expect(skills).toHaveLength(1);
+    expect(skills[0].name).toBe('quoted-skill');
+    expect(skills[0].description).toBe(
+      'A skill with colons: like this one: and another.',
+    );
+  });
+
+  it('should parse skill with multi-line YAML description', async () => {
+    const skillDir = path.join(testRootDir, 'multiline-skill');
+    await fs.mkdir(skillDir, { recursive: true });
+    const skillFile = path.join(skillDir, 'SKILL.md');
+    await fs.writeFile(
+      skillFile,
+      `---
+name: multiline-skill
+description:
+  Expertise in reviewing code for style, security, and performance. Use when the
+  user asks for "feedback," a "review," or to "check" their changes.
+---
+# Instructions
+Do something.
+`,
+    );
+
+    const skills = await loadSkillsFromDir(testRootDir);
+
+    expect(skills).toHaveLength(1);
+    expect(skills[0].name).toBe('multiline-skill');
+    expect(skills[0].description).toContain('Expertise in reviewing code');
+    expect(skills[0].description).toContain('check');
+  });
 });

packages/core/src/skills/skillLoader.ts

@@ -32,6 +32,74 @@ export interface SkillDefinition {
 export const FRONTMATTER_REGEX =
   /^---\r?\n([\s\S]*?)\r?\n---(?:\r?\n([\s\S]*))?/;
 
+/**
+ * Parses frontmatter content using YAML with a fallback to simple key-value parsing.
+ * This handles cases where description contains colons that would break YAML parsing.
+ */
+function parseFrontmatter(
+  content: string,
+): { name: string; description: string } | null {
+  try {
+    const parsed = yaml.load(content);
+    if (parsed && typeof parsed === 'object') {
+      const { name, description } = parsed as Record<string, unknown>;
+      if (typeof name === 'string' && typeof description === 'string') {
+        return { name, description };
+      }
+    }
+  } catch (yamlError) {
+    debugLogger.debug(
+      'YAML frontmatter parsing failed, falling back to simple parser:',
+      yamlError,
+    );
+  }
+
+  return parseSimpleFrontmatter(content);
+}
+
+/**
+ * Simple frontmatter parser that extracts name and description fields.
+ * Handles cases where values contain colons that would break YAML parsing.
+ */
+function parseSimpleFrontmatter(
+  content: string,
+): { name: string; description: string } | null {
+  const lines = content.split(/\r?\n/);
+  let name: string | undefined;
+  let description: string | undefined;
+
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i];
+
+    if (line.startsWith('name:')) {
+      name = line.substring(5).trim();
+      continue;
+    }
+
+    if (line.startsWith('description:')) {
+      const descLines = [line.substring(12).trim()];
+
+      while (i + 1 < lines.length) {
+        const nextLine = lines[i + 1];
+        if (nextLine.match(/^[ \t]+\S/)) {
+          descLines.push(nextLine.trim());
+          i++;
+        } else {
+          break;
+        }
+      }
+
+      description = descLines.filter(Boolean).join(' ');
+      continue;
+    }
+  }
+
+  if (name !== undefined && description !== undefined) {
+    return { name, description };
+  }
+  return null;
+}
+
 /**
  * Discovers and loads all skills in the provided directory.
  */
@@ -92,19 +160,14 @@ export async function loadSkillFromFile(
       return null;
     }
 
-    const frontmatter = yaml.load(match[1]);
-    if (!frontmatter || typeof frontmatter !== 'object') {
-      return null;
-    }
-
-    const { name, description } = frontmatter as Record<string, unknown>;
-    if (typeof name !== 'string' || typeof description !== 'string') {
+    const frontmatter = parseFrontmatter(match[1]);
+    if (!frontmatter) {
       return null;
     }
 
     return {
-      name,
-      description,
+      name: frontmatter.name,
+      description: frontmatter.description,
       location: filePath,
       body: match[2].trim(),
     };