feat(validator): lint personas for name, description and Composition

The smaller version asked for when #610 was closed. docs/agents.md states
three rules for agents/<name>.md — the same frontmatter format as a skill
with name equal to the file stem (the name is the subagent_type commands
spawn) and a description, and a closing Composition block — and no
validator checked them.

Add lintPersonaContent to scripts/lib/skill-lint.js, reusing the existing
frontmatter parsing and YAML-validity rules, and have validate-skills.js
walk agents/*.md after the skills, skipping an index README.md. Headings
are read from fence-stripped content so an example block after
Composition does not count as a later section. No spawn-reference
scanning, no listing-table checks, no new script, no workflow change.

All four personas pass: 25 skills and 4 personas checked, 0 errors.

scripts/lib/skill-lint-test.js

@@ -9,7 +9,7 @@ const fs   = require('node:fs');
 const os   = require('node:os');
 const path = require('node:path');
 
-const { lintSkillContent, lintSkillLayout, topLevelFrontmatterKeys } = require('./skill-lint.js');
+const { lintSkillContent, lintSkillLayout, topLevelFrontmatterKeys, lintPersonaContent } = require('./skill-lint.js');
 
 const KNOWN = new Set(['alpha', 'beta']);
 
@@ -648,3 +648,69 @@ test('the spec-key check tolerates CRLF frontmatter', () => {
   const { errors } = lintSkillContent('alpha', content, KNOWN);
   assert.equal(errors.filter(e => /key 'temperature'/.test(e)).length, 1);
 });
+
+// ─── Personas (agents/<name>.md) ─────────────────────────────────────────────
+//
+// docs/agents.md: same frontmatter format as a skill, name equal to the file
+// stem, and the file ends with a Composition block. Nothing more is checked.
+
+function personaFile({ name = 'code-reviewer', description = 'Reviews changes. Use before merging.', body } = {}) {
+  const fm = ['---', name === null ? null : `name: ${name}`, description === null ? null : `description: ${description}`, '---']
+    .filter(l => l !== null).join('\n');
+  return `${fm}\n\n${body ?? '# Persona\n\n## Rules\n\nBe precise.\n\n## Composition\n\n- **Invoke via:** `/ship`.\n'}`;
+}
+
+test('a conforming persona produces no errors', () => {
+  assert.deepEqual(lintPersonaContent('code-reviewer', personaFile()).errors, []);
+});
+
+test('persona: frontmatter name must match the file stem', () => {
+  const { errors } = lintPersonaContent('code-reviewer', personaFile({ name: 'reviewer' }));
+  assert.equal(errors.length, 1);
+  assert.match(errors[0], /name 'reviewer' does not match file name 'code-reviewer'/);
+});
+
+test('persona: description is required', () => {
+  const { errors } = lintPersonaContent('code-reviewer', personaFile({ description: null }));
+  assert.equal(errors.length, 1);
+  assert.match(errors[0], /missing required field: 'description'/);
+});
+
+test('persona: a missing frontmatter block is reported and nothing else is attempted', () => {
+  const { errors } = lintPersonaContent('code-reviewer', '# Persona\n\n## Composition\n');
+  assert.equal(errors.length, 1);
+  assert.match(errors[0], /Missing or malformed YAML frontmatter/);
+});
+
+test('persona: frontmatter a host would reject as YAML is reported', () => {
+  const { errors } = lintPersonaContent('code-reviewer', personaFile({ description: 'Reviews: everything. Use before merging.' }));
+  assert.equal(errors.length, 1);
+  assert.match(errors[0], /Frontmatter line/);
+});
+
+test('persona: the Composition section is required', () => {
+  const { errors } = lintPersonaContent('code-reviewer', personaFile({ body: '# Persona\n\n## Rules\n\nBe precise.\n' }));
+  assert.equal(errors.length, 1);
+  assert.match(errors[0], /Missing "## Composition" section/);
+});
+
+test('persona: Composition must be the last section', () => {
+  const { errors } = lintPersonaContent('code-reviewer', personaFile({
+    body: '# Persona\n\n## Composition\n\n- **Invoke via:** `/ship`.\n\n## Output Format\n\nA report.\n',
+  }));
+  assert.equal(errors.length, 1);
+  assert.match(errors[0], /must be the last section, but "## Output Format" follows it/);
+});
+
+test('persona: a heading inside a fenced example after Composition is not a later section', () => {
+  const body = [
+    '# Persona', '', '## Composition', '', '- **Invoke via:** `/ship`. Report in this shape:', '',
+    '```markdown', '## Review: [title]', 'Findings…', '```', '',
+  ].join('\n');
+  assert.deepEqual(lintPersonaContent('code-reviewer', personaFile({ body })).errors, []);
+});
+
+test('persona: the Composition heading match is case-insensitive and tolerates trailing spaces', () => {
+  const body = '# Persona\n\n## composition   \n\n- **Invoke via:** `/ship`.\n';
+  assert.deepEqual(lintPersonaContent('code-reviewer', personaFile({ body })).errors, []);
+});

scripts/lib/skill-lint.js

@@ -543,6 +543,59 @@ function lintSkillLayout(skillDir) {
   return errors;
 }
 
+/**
+ * Lint a persona file (agents/<name>.md) against the three rules docs/agents.md
+ * states for them: frontmatter in the same format as a skill, with `name`
+ * equal to the file stem (the name is the `subagent_type` commands spawn) and
+ * a `description`; and a closing `## Composition` section. Headings inside
+ * fenced blocks are ignored, so an example after Composition does not count as
+ * a later section. Pure: no filesystem access. Returns { errors }.
+ */
+function lintPersonaContent(stem, content) {
+  const errors = [];
+
+  const fm = parseFrontmatter(content);
+  if (!fm) {
+    errors.push('Missing or malformed YAML frontmatter (expected --- block at top of file)');
+    return { errors };
+  }
+  errors.push(...frontmatterYamlErrors(content));
+
+  if (!fm.name) {
+    errors.push("Frontmatter missing required field: 'name'");
+  } else if (fm.name !== stem) {
+    errors.push(`Frontmatter name '${fm.name}' does not match file name '${stem}' (the name is the subagent_type commands spawn)`);
+  }
+  if (!fm.description) {
+    errors.push("Frontmatter missing required field: 'description'");
+  }
+
+  const headings = [...stripFencedCodeBlocks(content).matchAll(/^## +(.+?)\s*$/gm)].map(m => m[1]);
+  const compositionAt = headings.findIndex(h => /^Composition$/i.test(h));
+  if (compositionAt === -1) {
+    errors.push('Missing "## Composition" section (docs/agents.md: every persona file ends with a Composition block)');
+  } else if (compositionAt !== headings.length - 1) {
+    errors.push(`"## Composition" must be the last section, but "## ${headings[headings.length - 1]}" follows it`);
+  }
+
+  return { errors };
+}
+
+/**
+ * Lint a persona by file name: reads agents/<file>, then delegates to
+ * lintPersonaContent. Returns { errors }.
+ */
+function lintPersona(fileName, agentsDir) {
+  const stem = fileName.replace(/\.md$/, '');
+  let content;
+  try {
+    content = fs.readFileSync(path.join(agentsDir, fileName), 'utf8');
+  } catch (err) {
+    return { errors: [`Unreadable persona file: ${err.message}`] };
+  }
+  return lintPersonaContent(stem, content);
+}
+
 /**
  * Lint a skill by directory name: reads its SKILL.md, then delegates to
  * lintSkillContent. This is the thin filesystem wrapper the CLI uses.
@@ -581,4 +634,6 @@ module.exports = {
   lintSkillContent,
   lintSkillLayout,
   lintSkill,
+  lintPersonaContent,
+  lintPersona,
 };

scripts/validate-skills.js

@@ -3,7 +3,8 @@
  * validate-skills.js
  *
  * CLI that validates every skill in skills/ against the rules in
- * docs/skill-anatomy.md. The rules themselves live in scripts/lib/skill-lint.js
+ * docs/skill-anatomy.md, and every persona in agents/ against the three rules
+ * in docs/agents.md. The rules themselves live in scripts/lib/skill-lint.js
  * (a single source of truth, importable and unit-testable); this file is a thin
  * wrapper that walks the skills directory, runs the linter, prints the report,
  * and sets the exit code.
@@ -16,9 +17,10 @@
 const fs   = require('fs');
 const path = require('path');
 
-const { lintSkill } = require('./lib/skill-lint');
+const { lintSkill, lintPersona } = require('./lib/skill-lint');
 
 const SKILLS_DIR = path.resolve(__dirname, '..', 'skills');
+const AGENTS_DIR = path.resolve(__dirname, '..', 'agents');
 
 // ─── Main ────────────────────────────────────────────────────────────────────
 
@@ -53,8 +55,29 @@ function main() {
     }
   }
 
+  // ── Personas ─────────────────────────────────────────────────────────────
+  // agents/<name>.md files are consumed as subagents and spawned by name from
+  // commands, so they get the same frontmatter contract plus a closing
+  // Composition section (docs/agents.md). An index file such as README.md is
+  // not a persona and is skipped.
+  const personaFiles = fs.existsSync(AGENTS_DIR)
+    ? fs.readdirSync(AGENTS_DIR).filter(f => f.endsWith('.md') && !/^readme\.md$/i.test(f)).sort()
+    : [];
+
+  if (personaFiles.length > 0) console.log('');
+  for (const fileName of personaFiles) {
+    const { errors } = lintPersona(fileName, AGENTS_DIR);
+    totalErrors += errors.length;
+    if (errors.length === 0) {
+      console.log(`  ✓  agents/${fileName}`);
+    } else {
+      console.log(`  ✗  agents/${fileName}`);
+      for (const msg of errors) console.log(`       ERROR: ${msg}`);
+    }
+  }
+
   const status = totalErrors > 0 ? 'FAILED' : totalWarnings > 0 ? 'PASSED WITH WARNINGS' : 'PASSED';
-  console.log(`\n${skillDirs.length} skills checked — ${totalErrors} error(s), ${totalWarnings} warning(s) — ${status}`);
+  console.log(`\n${skillDirs.length} skills and ${personaFiles.length} personas checked — ${totalErrors} error(s), ${totalWarnings} warning(s) — ${status}`);
 
   if (totalErrors > 0) process.exit(1);
 }