diff --git a/README.md b/README.md
index 9c29878..2597985 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,8 @@ It explains how to combine a strong planning/review model with faster workers,
 reusable skills, subagent handoffs, Git worktrees, and explicit verification.
 An interactive field kit compares common behavior skills such as
 `ponytail-lite`, `caveman`, `unlazy`, research, debugging, and review.
+The skill-forge workflow covers discovery, triggers, package anatomy,
+progressive instructions, structural validation, and behavioral iteration.
 
 ## Run locally
 
diff --git a/app.js b/app.js
index 71880b6..b17f13a 100644
--- a/app.js
+++ b/app.js
@@ -28,6 +28,13 @@ const interactiveCopy = {
     scripts: { icon: '›_', title: 'scripts/', en: 'Deterministic checks and repeated operations. Prefer executable proof over prose.', pt: 'Verificações determinísticas e operações repetidas. Prefira prova executável a prosa.' },
     assets: { icon: '▧', title: 'assets/', en: 'Templates and examples the agent can copy without reinventing the expected shape.', pt: 'Templates e exemplos que o agente pode copiar sem reinventar o formato esperado.' }
   },
+  skillWorkflow: {
+    observe: { number: '01', title: { en: 'Start from repeated friction', pt: 'Comece pelo atrito repetido' }, question: { en: 'Which non-obvious decision keeps being rediscovered?', pt: 'Qual decisão não óbvia continua sendo redescoberta?' }, action: { en: 'Collect two or three realistic requests. Separate durable judgment from one project’s temporary details.', pt: 'Colete dois ou três pedidos realistas. Separe julgamento durável dos detalhes temporários de um projeto.' }, output: { en: 'A narrow capability and concrete examples.', pt: 'Uma capacidade estreita e exemplos concretos.' }, proof: { en: 'Without the skill, agents repeatedly make the same avoidable mistake.', pt: 'Sem a skill, agentes repetem o mesmo erro evitável.' } },
+    trigger: { number: '02', title: { en: 'Make discovery precise', pt: 'Torne a descoberta precisa' }, question: { en: 'When should this load—and when should it stay out?', pt: 'Quando isto deve carregar — e quando deve ficar de fora?' }, action: { en: 'Choose a short action-oriented name. Write a discriminating description that names the task and meaningful boundary.', pt: 'Escolha um nome curto orientado à ação. Escreva uma descrição discriminante que nomeie a tarefa e seu limite.' }, output: { en: 'YAML name + description in SKILL.md.', pt: 'Nome + descrição YAML em SKILL.md.' }, proof: { en: 'Relevant prompts select it; nearby unrelated prompts do not.', pt: 'Prompts relevantes selecionam; prompts próximos mas não relacionados, não.' } },
+    scaffold: { number: '03', title: { en: 'Choose only useful anatomy', pt: 'Escolha apenas a anatomia útil' }, question: { en: 'What must be instructions, executable, consulted, or copied?', pt: 'O que deve ser instrução, executável, consultado ou copiado?' }, action: { en: 'Keep shared guidance in SKILL.md. Add scripts for repeated deterministic work, references for conditional facts, and assets for generated output.', pt: 'Mantenha orientação comum em SKILL.md. Adicione scripts para trabalho determinístico, referências para fatos condicionais e assets para saída.' }, output: { en: 'Smallest folder structure that supports the workflow.', pt: 'A menor estrutura de pastas que sustenta o fluxo.' }, proof: { en: 'Every file has a real caller; no placeholder directories.', pt: 'Cada arquivo tem um consumidor real; nenhuma pasta placeholder.' } },
+    write: { number: '04', title: { en: 'Write what changes decisions', pt: 'Escreva o que muda decisões' }, question: { en: 'What would a capable agent still get wrong?', pt: 'O que um agente capaz ainda erraria?' }, action: { en: 'State outcome, non-obvious constraints, routing, and stopping conditions. Remove generic advice, duplicate facts, and speculative rules.', pt: 'Declare resultado, restrições não óbvias, roteamento e condições de parada. Remova conselhos genéricos, fatos duplicados e regras especulativas.' }, output: { en: 'Lean SKILL.md with progressive links.', pt: 'SKILL.md enxuto com links progressivos.' }, proof: { en: 'Another agent can act correctly without loading irrelevant detail.', pt: 'Outro agente consegue agir corretamente sem carregar detalhes irrelevantes.' } },
+    validate: { number: '05', title: { en: 'Test behavior, then sharpen', pt: 'Teste comportamento, depois refine' }, question: { en: 'Did the skill improve a realistic outcome?', pt: 'A skill melhorou um resultado realista?' }, action: { en: 'Run structural validation, execute every new script, and forward-test realistic requests. Fix observed failures with the narrowest rule.', pt: 'Execute validação estrutural, rode cada script novo e teste pedidos realistas. Corrija falhas observadas com a regra mais estreita.' }, output: { en: 'Validated package plus evidence from real use.', pt: 'Pacote validado mais evidência de uso real.' }, proof: { en: 'quick_validate passes and behavior improves without unrelated side effects.', pt: 'quick_validate passa e o comportamento melhora sem efeitos colaterais.' } }
+  },
   commonSkills: {
     ponytail: { number: '01', kind: { en: 'SIMPLIFICATION INSTINCT', pt: 'INSTINTO DE SIMPLIFICAÇÃO' }, title: 'ponytail-lite', rule: { en: 'Stop at the first rung that holds.', pt: 'Pare no primeiro degrau que sustenta.' }, use: { en: 'Use when a request invites frameworks, dependencies, abstractions, or speculative scaffolding. It checks reuse, standard library, and native platform features before adding code.', pt: 'Use quando um pedido convida frameworks, dependências, abstrações ou scaffolding especulativo. Verifica reúso, biblioteca padrão e recursos nativos antes de adicionar código.' }, example: { en: 'Date picker? Start with <input type="date">.', pt: 'Seletor de data? Comece com <input type="date">.' }, caution: { en: 'Never simplify away security, accessibility, validation, or real edge cases.', pt: 'Nunca simplifique segurança, acessibilidade, validação ou casos extremos reais.' } },
     caveman: { number: '02', kind: { en: 'COMMUNICATION STYLE', pt: 'ESTILO DE COMUNICAÇÃO' }, title: 'caveman', rule: { en: 'Signal first. Drop filler.', pt: 'Sinal primeiro. Corte o excesso.' }, use: { en: 'Use for routine status, handoffs, and technical summaries where speed matters. Short fragments make actions and evidence easy to scan.', pt: 'Use em status, handoffs e resumos técnicos rotineiros onde velocidade importa. Fragmentos curtos facilitam localizar ações e evidências.' }, example: { en: 'Built. Tests pass. Published.', pt: 'Feito. Testes passaram. Publicado.' }, caution: { en: 'Drop the style for security warnings, irreversible actions, and sequences where terse wording can be misread.', pt: 'Abandone o estilo em alertas de segurança, ações irreversíveis e sequências onde concisão pode causar erro.' } },
@@ -41,7 +48,7 @@ const interactiveCopy = {
 
 const translations = {
   pt: {
-    '.chapter-links a:nth-child(1)': '01 frota', '.chapter-links a:nth-child(2)': '02 worktrees', '.chapter-links a:nth-child(3)': '03 skills', '.chapter-links a:nth-child(4)': '04 kit de campo', '.edition': 'ENGENHARIA DE IA <i></i> 01 / 2026',
+    '.chapter-links a:nth-child(1)': '01 frota', '.chapter-links a:nth-child(2)': '02 worktrees', '.chapter-links a:nth-child(3)': '03 skills', '.chapter-links a:nth-child(4)': '04 criar', '.chapter-links a:nth-child(5)': '05 kit de campo', '.edition': 'ENGENHARIA DE IA <i></i> 01 / 2026',
     '.hero .eyebrow': 'Uma apresentação para quem entrega software', '.lede': 'Você não precisa de um exército de modelos. Precisa de um sistema: uma mente para enquadrar o trabalho, várias mãos para executá-lo e uma fronteira clara entre cada tarefa.', '.hero-index span': 'NOTA DE CAMPO / 001', '.hero-index strong': 'Entregue o<br /><em>sistema.</em>', '.hero-index small': 'Skills · agentes · worktrees · evidências',
     '.hero-stats div:nth-child(1) span': 'modelo forte<br />para ambiguidade', '.hero-stats div:nth-child(2) span': 'workers delimitados<br />em paralelo', '.hero-stats div:nth-child(3) span': 'iterações<br />com evidências', '.hero-stats p': 'Leia isto como um mapa de rota, não como uma receita de prompt.',
     '.thesis span': 'REGRA ZERO', '.thesis strong': 'Modelo forte para ambiguidade.<br />Modelo leve para trabalho delimitado.', '.fleet .section-label span:nth-child(1)': 'Uma pequena frota', '.fleet .section-label span:nth-child(2)': 'coordenação antes do paralelismo', '.captain span': 'ORQUESTRADOR', '.captain h2': 'Decide o que<br />precisa acontecer.', '.worker-card[data-worker="ui"] strong': 'Componentes e estados visuais', '.worker-card[data-worker="tests"] strong': 'Casos de aceitação', '.worker-card[data-worker="docs"] strong': 'Guia e exemplos', '.caption': 'O orquestrador preserva a intenção, escreve pequenos contratos e reúne resultados verificáveis. Ele não precisa digitar cada linha.',
@@ -52,6 +59,22 @@ const translations = {
   }
 };
 
+Object.assign(translations.pt, {
+  '.skill-builder .section-label span:nth-child(1)': 'Criar uma skill',
+  '.skill-builder .section-label span:nth-child(2)': 'atrito repetido → julgamento reutilizável',
+  '.builder-intro .eyebrow': 'A forja de skills',
+  '.builder-intro h2': 'Ensine a decisão.<br />Mantenha o contexto <em>leve.</em>',
+  '.builder-intro > p': 'Não empacote tudo o que você sabe. Capture as escolhas não óbvias que melhoram resultados repetidamente e prove que a skill muda o comportamento.',
+  '[data-skill-step="observe"] span': 'Observar', '[data-skill-step="observe"] small': 'encontre atrito repetido',
+  '[data-skill-step="trigger"] span': 'Definir gatilho', '[data-skill-step="trigger"] small': 'roteie com precisão',
+  '[data-skill-step="scaffold"] span': 'Escolher anatomia', '[data-skill-step="scaffold"] small': 'apenas arquivos necessários',
+  '[data-skill-step="write"] span': 'Escrever orientação', '[data-skill-step="write"] small': 'decisões, não trivialidades',
+  '[data-skill-step="validate"] span': 'Validar', '[data-skill-step="validate"] small': 'teste comportamento real',
+  '.artifact-head span': 'SAÍDA / PACOTE DE SKILL', '.artifact-command span': 'VALIDAR',
+  '.builder-loop > span': 'APÓS USO REAL',
+  '.builder-loop > div': '<b>observar falha</b><i>→</i><b>refinar uma regra</b><i>→</i><b>retestar comportamento</b><i>→</i><b>manter estreita</b>'
+});
+
 const panel = document.querySelector('#phase-panel');
 const buttons = document.querySelectorAll('[data-phase]');
 const originals = new Map();
@@ -104,6 +127,16 @@ function renderSkillFile(id) {
   selectButtons('[data-skill-file]', id, 'skillFile');
 }
 
+function renderSkillWorkflow(id) {
+  const item = interactiveCopy.skillWorkflow[id];
+  const language = currentLanguage;
+  const labels = language === 'pt'
+    ? ['PERGUNTA', 'AÇÃO', 'ARTEFATO', 'PROVA']
+    : ['QUESTION', 'ACTION', 'ARTIFACT', 'PROOF'];
+  document.querySelector('#builder-detail').innerHTML = `<header><span>${item.number}</span><small>${labels[0]}</small></header><h3>${item.title[language]}</h3><blockquote>${item.question[language]}</blockquote><div class="builder-action"><span>${labels[1]}</span><p>${item.action[language]}</p></div><footer><div><span>${labels[2]}</span><strong>${item.output[language]}</strong></div><div><span>${labels[3]}</span><strong>${item.proof[language]}</strong></div></footer>`;
+  selectButtons('[data-skill-step]', id, 'skillStep');
+}
+
 function renderCommonSkill(id) {
   const item = interactiveCopy.commonSkills[id];
   const language = currentLanguage;
@@ -119,6 +152,7 @@ function renderInteractive() {
   renderTree(document.querySelector('[data-tree].active')?.dataset.tree || 'main');
   renderRoute(document.querySelector('[data-route].active')?.dataset.route || 'plan');
   renderSkillFile(document.querySelector('[data-skill-file].active')?.dataset.skillFile || 'skill');
+  renderSkillWorkflow(document.querySelector('[data-skill-step].active')?.dataset.skillStep || 'observe');
   renderCommonSkill(document.querySelector('[data-common-skill].active')?.dataset.commonSkill || 'ponytail');
 }
 
@@ -139,6 +173,7 @@ document.querySelectorAll('[data-worker]').forEach((button) => button.addEventLi
 document.querySelectorAll('[data-tree]').forEach((button) => button.addEventListener('click', () => renderTree(button.dataset.tree)));
 document.querySelectorAll('[data-route]').forEach((button) => button.addEventListener('click', () => renderRoute(button.dataset.route)));
 document.querySelectorAll('[data-skill-file]').forEach((button) => button.addEventListener('click', () => renderSkillFile(button.dataset.skillFile)));
+document.querySelectorAll('[data-skill-step]').forEach((button) => button.addEventListener('click', () => renderSkillWorkflow(button.dataset.skillStep)));
 document.querySelectorAll('[data-common-skill]').forEach((button) => button.addEventListener('click', () => renderCommonSkill(button.dataset.commonSkill)));
 window.addEventListener('scroll', () => { const height = document.documentElement.scrollHeight - window.innerHeight; document.querySelector('.reading-progress span').style.width = `${height > 0 ? (window.scrollY / height) * 100 : 0}%`; }, { passive: true });
 
diff --git a/index.html b/index.html
index 8f58034..c31cd86 100644
--- a/index.html
+++ b/index.html
@@ -11,7 +11,7 @@
 <body>
 <div class="reading-progress" aria-hidden="true"><span></span></div>
 <main>
-<header class="topbar"><a class="brand" href="#top"><span class="mark">A</span> field guide</a><nav class="chapter-links" aria-label="Chapter sections"><a href="#fleet">01 fleet</a><a href="#worktrees">02 worktrees</a><a href="#skills">03 skills</a><a href="#field-kit">04 field kit</a></nav><div class="topbar-tools"><div class="lang-switch" aria-label="Language"><button class="active" data-lang="en" aria-pressed="true">EN</button><span>/</span><button data-lang="pt" aria-pressed="false">PT</button></div><span class="edition">AI ENGINEERING <i></i> 01 / 2026</span></div></header>
+<header class="topbar"><a class="brand" href="#top"><span class="mark">A</span> field guide</a><nav class="chapter-links" aria-label="Chapter sections"><a href="#fleet">01 fleet</a><a href="#worktrees">02 worktrees</a><a href="#skills">03 skills</a><a href="#create-skill">04 create</a><a href="#field-kit">05 field kit</a></nav><div class="topbar-tools"><div class="lang-switch" aria-label="Language"><button class="active" data-lang="en" aria-pressed="true">EN</button><span>/</span><button data-lang="pt" aria-pressed="false">PT</button></div><span class="edition">AI ENGINEERING <i></i> 01 / 2026</span></div></header>
 <section class="hero" id="top"><div><p class="eyebrow">A presentation for humans who ship</p><h1>AI for<br /><em>dummies.</em></h1><p class="lede">You do not need an army of models. You need a system: one mind to frame the work, several hands to execute it, and a clean boundary between every task.</p></div><aside class="hero-index"><span>FIELD NOTE / 001</span><strong>Ship the<br /><em>system.</em></strong><small>Skills · agents · worktrees · proof</small></aside></section>
 <section class="hero-stats" aria-label="Chapter summary"><div><strong>01</strong><span>strong model<br />for ambiguity</span></div><div><strong>03</strong><span>bounded workers<br />in parallel</span></div><div><strong>∞</strong><span>iterations<br />with evidence</span></div><p>Read this as a route map, not a prompt recipe.</p></section>
 <section class="thesis"><div><span>RULE ZERO</span><strong>Strong model for ambiguity.<br />Light model for bounded work.</strong></div><div class="signal" aria-hidden="true"><b>THINK</b><i></i><i></i><i></i><b>MAKE</b></div></section>
@@ -22,6 +22,7 @@
 <section class="worktrees" id="worktrees"><div class="worktree-intro"><p class="eyebrow">Git worktrees</p><h2>One branch<br />per <em>hand.</em></h2><p>A worktree is another directory linked to the same repository. Each agent gets its own checkout and index; history remains shared.</p><p class="interaction-hint">Select a node to inspect its checkout, owner, and next action.</p></div><div class="tree-lab"><div class="tree-toolbar"><span>repository topology</span><span class="tree-live"><i></i> 4 checkouts</span></div><div class="tree-stage" role="tree" aria-label="Repository worktree topology"><svg viewBox="0 0 760 330" preserveAspectRatio="none" aria-hidden="true"><path class="tree-edge trunk" d="M380 48 V118"/><path class="tree-edge" d="M380 118 C380 170 110 150 110 224"/><path class="tree-edge" d="M380 118 V224"/><path class="tree-edge" d="M380 118 C380 170 650 150 650 224"/></svg><button class="tree-node root active" data-tree="main" role="treeitem" aria-selected="true"><span>ROOT</span><strong>main</strong><small>● clean</small></button><button class="tree-node branch ui" data-tree="ui" role="treeitem" aria-selected="false"><span>UI AGENT</span><strong>agent/ui</strong><small>3 files · working</small></button><button class="tree-node branch tests" data-tree="tests" role="treeitem" aria-selected="false"><span>TEST AGENT</span><strong>agent/tests</strong><small>8 checks · ready</small></button><button class="tree-node branch docs" data-tree="docs" role="treeitem" aria-selected="false"><span>DOCS AGENT</span><strong>agent/docs</strong><small>2 pages · review</small></button></div><article class="tree-detail" id="tree-detail" aria-live="polite"></article></div></section>
 <section class="routing"><div><p class="eyebrow">Model routing</p><h2>Do not pay for<br />reasoning where<br />you need <em>rhythm.</em></h2><p class="interaction-hint">Choose a job to see why the model profile changes.</p></div><div class="route-console"><div class="route-table"><div class="head"><span>Work</span><span>Profile</span><span>Prompt shape</span></div><button class="active" data-route="plan" aria-pressed="true"><strong>Plan</strong><b>strong / broad</b><small>What changes? What can break?</small></button><button data-route="build" aria-pressed="false"><strong>Build</strong><b>fast / focused</b><small>Implement this slice. Run these checks.</small></button><button data-route="explore" aria-pressed="false"><strong>Explore</strong><b>read-only / light</b><small>Find where this contract is used.</small></button><button data-route="review" aria-pressed="false"><strong>Review</strong><b>independent</b><small>Does the diff satisfy the brief?</small></button></div><article class="route-detail" id="route-detail" aria-live="polite"></article></div></section>
 <section class="skills" id="skills"><div><p class="eyebrow">Skills</p><h2>Write the right way<br /><em>once.</em></h2><p>A skill is a reusable procedure. It can carry instructions, references, scripts, and assets. It is not magical memory, and it does not replace acceptance criteria.</p><div class="skill-principles"><span>01 / trigger clearly</span><span>02 / load detail on demand</span><span>03 / return evidence</span></div></div><div class="skill-explorer"><div class="skill-package" role="tree" aria-label="Skill package files"><span>SKILL PACKAGE</span><button class="active" data-skill-file="skill" role="treeitem" aria-selected="true"><code>SKILL.md</code><small>procedure and limits</small></button><button data-skill-file="references" role="treeitem" aria-selected="false"><code>references/</code><small>facts to consult</small></button><button data-skill-file="scripts" role="treeitem" aria-selected="false"><code>scripts/</code><small>repeatable checks</small></button><button data-skill-file="assets" role="treeitem" aria-selected="false"><code>assets/</code><small>templates and examples</small></button></div><article class="skill-detail" id="skill-detail" aria-live="polite"></article></div><pre><code>name: review-ui · check focus, mobile, reduced motion · run verification · return evidence</code></pre></section>
+<section class="skill-builder" id="create-skill"><div class="section-label"><span>Create a skill</span><span>repeatable pain → reusable judgment</span></div><div class="builder-intro"><div><p class="eyebrow">The skill forge</p><h2>Teach the decision.<br />Keep the context <em>light.</em></h2></div><p>Do not package everything you know. Capture the non-obvious choices that repeatedly improve an outcome, then prove the skill changes behavior.</p></div><div class="builder-workbench"><nav class="builder-steps" role="tablist" aria-label="Skill creation workflow"><button class="active" data-skill-step="observe" role="tab" aria-selected="true"><b>01</b><span>Observe</span><small>find repeated friction</small></button><button data-skill-step="trigger" role="tab" aria-selected="false"><b>02</b><span>Define trigger</span><small>route precisely</small></button><button data-skill-step="scaffold" role="tab" aria-selected="false"><b>03</b><span>Choose anatomy</span><small>only needed files</small></button><button data-skill-step="write" role="tab" aria-selected="false"><b>04</b><span>Write guidance</span><small>decisions, not trivia</small></button><button data-skill-step="validate" role="tab" aria-selected="false"><b>05</b><span>Validate</span><small>test real behavior</small></button></nav><article class="builder-detail" id="builder-detail" aria-live="polite"></article><aside class="builder-artifact"><div class="artifact-head"><span>OUTPUT / SKILL PACKAGE</span><i></i></div><pre aria-label="Example skill structure"><code>review-ui/<br />├── SKILL.md<br />├── agents/<br />│   └── openai.yaml<br />├── references/<br />│   └── accessibility.md<br />└── scripts/<br />    └── verify.mjs</code></pre><div class="artifact-command"><span>VALIDATE</span><code>quick_validate.py ./review-ui</code></div></aside></div><div class="builder-loop"><span>AFTER REAL USE</span><div><b>observe failure</b><i>→</i><b>sharpen one rule</b><i>→</i><b>retest behavior</b><i>→</i><b>keep it narrow</b></div></div></section>
 <section class="skill-catalog" id="field-kit"><div class="section-label"><span>Common skills</span><span>choose behavior before model</span></div><div class="catalog-intro"><div><p class="eyebrow">The field kit</p><h2>Different jobs.<br />Different <em>instincts.</em></h2></div><p>A skill changes how an agent approaches work. Some shape communication. Others enforce research, debugging, review, or completion discipline. Select one to inspect its operating rule.</p></div><div class="skill-deck"><div class="skill-index" role="tablist" aria-label="Common agent skills"><button class="active" data-common-skill="ponytail" role="tab" aria-selected="true"><span>SIMPLIFY</span><strong>ponytail-lite</strong><small>minimum code that holds</small></button><button data-common-skill="caveman" role="tab" aria-selected="false"><span>COMMUNICATE</span><strong>caveman</strong><small>signal without filler</small></button><button data-common-skill="unlazy" role="tab" aria-selected="false"><span>COMPLETE</span><strong>unlazy</strong><small>gates and evidence</small></button><button data-common-skill="research" role="tab" aria-selected="false"><span>INVESTIGATE</span><strong>research</strong><small>primary sources first</small></button><button data-common-skill="debug" role="tab" aria-selected="false"><span>DIAGNOSE</span><strong>diagnosing-bugs</strong><small>tight feedback loop</small></button><button data-common-skill="review" role="tab" aria-selected="false"><span>REVIEW</span><strong>code-review</strong><small>standards × spec</small></button><button data-common-skill="tokens" role="tab" aria-selected="false"><span>ECONOMIZE</span><strong>token-saver</strong><small>compress noisy output</small></button></div><article class="common-skill-detail" id="common-skill-detail" aria-live="polite"></article></div><div class="skill-loadout"><span>ONE PRACTICAL LOADOUT</span><div><b>PLAN</b> unlazy <i>→</i> <b>BUILD</b> ponytail-lite <i>→</i> <b>DEBUG</b> diagnosing-bugs <i>→</i> <b>REPORT</b> caveman</div></div></section>
 <aside class="rule"><span>THE HUMAN JOB</span><strong>The agent may be autonomous in execution. Intent, boundaries, and evidence remain yours.</strong></aside><aside class="callout"><span>START HERE</span><strong>Begin with one agent and one skill. Add parallelism only when the tasks are truly independent.</strong></aside>
 <section class="sources"><div class="section-label"><span>Keep learning</span><span>12 new readings + primary docs</span></div><p>Go deeper with official documentation, production case studies, Medium, and practitioner workflows. <a href="docs/references/README.md">Primary references →</a> <a href="docs/references/additional-reading.md">12-part reading path →</a></p></section>
diff --git a/responsive.css b/responsive.css
index 5807e0a..51191ec 100644
--- a/responsive.css
+++ b/responsive.css
@@ -36,6 +36,14 @@ button{font-family:inherit}
 .worker-card:focus-visible,.tree-node:focus-visible,.route-table button:focus-visible,.skill-package button:focus-visible{outline:3px solid var(--gold);outline-offset:-3px}
 
 /* Skill shelf */
+.skill-builder{margin-bottom:150px;padding-top:80px;border-top:1px solid var(--line)}
+.builder-intro{display:grid;grid-template-columns:.95fr 1.05fr;gap:70px;align-items:end;margin:45px 0}.builder-intro h2{margin-bottom:0}.builder-intro>p{max-width:620px;margin:0;color:var(--muted);font-size:14px;line-height:1.75}
+.builder-workbench{display:grid;grid-template-columns:minmax(220px,.65fr) minmax(380px,1.35fr) minmax(270px,.85fr);min-height:570px;border:1px solid var(--line);background:var(--line)}
+.builder-steps{display:grid;grid-template-rows:repeat(5,1fr);gap:1px;background:var(--line)}.builder-steps button{display:grid;grid-template-columns:42px 1fr;grid-template-rows:auto auto;align-content:center;column-gap:13px;padding:18px;border:0;color:var(--ink);background:var(--paper);text-align:left;cursor:pointer}.builder-steps button b{grid-row:1/-1;align-self:center;color:var(--accent);font:500 11px 'DM Mono',monospace}.builder-steps button span{font:700 12px 'DM Mono',monospace}.builder-steps button small{margin-top:5px;color:var(--muted);font-size:10px}.builder-steps button:hover{background:#eceff0}.builder-steps button.active{color:var(--paper);background:var(--blue);box-shadow:inset 5px 0 0 var(--gold)}.builder-steps button.active b,.builder-steps button.active small{color:var(--gold)}
+.builder-detail{display:grid;grid-template-rows:auto auto auto 1fr auto;align-content:start;padding:38px clamp(28px,4vw,58px);color:var(--paper);background:var(--deep)}.builder-detail header{display:flex;justify-content:space-between;align-items:center}.builder-detail header span{color:#ffffff30;font:500 54px 'DM Mono',monospace}.builder-detail header small,.builder-action span,.builder-detail footer span{color:var(--gold);font:500 8px 'DM Mono',monospace;letter-spacing:.1em}.builder-detail h3{margin:27px 0 14px;font-size:clamp(26px,3vw,44px);line-height:1.05;letter-spacing:-.05em}.builder-detail blockquote{margin:0;padding:0;color:#a9bcc8;font:italic 20px/1.35 Georgia,serif}.builder-action{align-self:center;margin:34px 0}.builder-action p{margin:11px 0 0;color:#d5dde2;font-size:13px;line-height:1.7}.builder-detail footer{display:grid;grid-template-columns:1fr 1fr;gap:1px;background:#ffffff2b}.builder-detail footer>div{display:grid;gap:10px;padding:17px;background:#18364a}.builder-detail footer strong{font-size:11px;line-height:1.5}
+.builder-artifact{display:grid;grid-template-rows:auto 1fr auto;color:var(--paper);background:#0b1b27}.artifact-head{display:flex;justify-content:space-between;padding:17px;border-bottom:1px solid #344c5d;font:500 8px 'DM Mono',monospace;letter-spacing:.09em}.artifact-head i{width:8px;height:8px;border-radius:50%;background:#80c69a;box-shadow:0 0 0 4px #80c69a20}.builder-artifact pre{display:grid;align-items:center;margin:0;padding:28px;overflow:auto;color:#bed0dc;background-image:linear-gradient(#ffffff05 1px,transparent 1px),linear-gradient(90deg,#ffffff05 1px,transparent 1px);background-size:22px 22px}.builder-artifact pre code{font:12px/1.9 'DM Mono',monospace}.artifact-command{display:grid;gap:9px;padding:18px;border-top:1px solid #344c5d}.artifact-command span{color:var(--gold);font:500 8px 'DM Mono',monospace;letter-spacing:.09em}.artifact-command code{font:10px 'DM Mono',monospace}
+.builder-loop{display:grid;grid-template-columns:200px 1fr;gap:25px;padding:23px 28px;color:var(--ink);background:var(--gold)}.builder-loop>span{font:700 9px 'DM Mono',monospace;letter-spacing:.09em}.builder-loop>div{font:600 11px 'DM Mono',monospace}.builder-loop i{margin:0 12px;color:var(--accent);font-style:normal}.builder-steps button:focus-visible{position:relative;z-index:2;outline:3px solid var(--gold);outline-offset:-3px}
+
 .skill-catalog{margin-bottom:130px;padding-top:80px;border-top:1px solid var(--line)}
 .catalog-intro{display:grid;grid-template-columns:.9fr 1.1fr;gap:70px;align-items:end;margin:45px 0}.catalog-intro h2{margin-bottom:0}.catalog-intro>p{max-width:620px;margin:0;color:var(--muted);font-size:14px;line-height:1.75}
 .skill-deck{display:grid;grid-template-columns:minmax(270px,.8fr) minmax(0,1.7fr);min-height:620px;border:1px solid var(--line);background:var(--line)}
@@ -46,7 +54,8 @@ button{font-family:inherit}
 .skill-loadout{display:grid;grid-template-columns:210px 1fr;gap:25px;padding:24px 28px;color:var(--paper);background:var(--ink)}.skill-loadout>span{color:var(--gold);font:500 9px 'DM Mono',monospace;letter-spacing:.09em}.skill-loadout>div{font:500 11px 'DM Mono',monospace}.skill-loadout b{color:var(--accent);font-size:9px}.skill-loadout i{margin:0 10px;color:var(--gold);font-style:normal}.skill-index button:focus-visible{position:relative;z-index:2;outline:3px solid var(--gold);outline-offset:-3px}
 @media(min-width:1600px){.tree-stage{height:390px}.tree-stage svg{height:330px;top:30px}.tree-node.root{top:45px}.tree-node.branch{top:255px}.tree-node{width:190px;padding:17px}.tree-detail{grid-template-columns:.6fr .8fr 1.8fr}.worker-card{min-height:210px;padding:28px}}
 @media(min-width:2200px){main{max-width:2880px;padding-inline:clamp(140px,7vw,280px)}.hero{max-width:1420px}.hero h1{font-size:clamp(150px,7vw,220px)}.tree-stage{height:460px}.tree-stage svg{height:380px;top:45px}.tree-node.root{top:65px}.tree-node.branch{top:305px}.tree-node{width:240px;padding:22px}.tree-node strong{font-size:15px}.tree-detail>*{font-size:14px!important}.fleet,.failure-map{margin-bottom:170px}.workflow,.routing,.skills{margin-bottom:180px}}
+@media(max-width:1100px){.chapter-links{display:none}.builder-workbench{grid-template-columns:minmax(210px,.65fr) minmax(0,1.35fr)}.builder-artifact{grid-column:1/-1;grid-template-columns:1fr 1fr;grid-template-rows:auto}.builder-artifact .artifact-head{grid-column:1/-1}.artifact-command{align-content:center;border-top:0;border-left:1px solid #344c5d}}
 @media(max-width:1050px){.tree-node{width:145px}.tree-detail{grid-template-columns:1fr 1fr}.tree-detail p{grid-column:1/-1}.skill-explorer{grid-template-columns:1fr}}
-@media(max-width:800px){.worker-detail{grid-template-columns:1fr}.worktrees{display:block}.worktree-intro{margin-bottom:40px}.tree-lab{box-shadow:9px 9px 0 #081621}.route-table button{min-width:620px}.skill-explorer{grid-template-columns:1fr 1fr}.catalog-intro{grid-template-columns:1fr;gap:20px}.skill-deck{grid-template-columns:1fr}.skill-index{grid-template-columns:1fr 1fr;grid-template-rows:none}.common-skill-detail{min-height:600px}.common-skill-notes{grid-template-columns:1fr 1fr}.common-skill-notes>div:first-child{grid-column:1/-1}}
-@media(max-width:600px){.tree-stage{height:auto;min-height:560px;padding:24px}.tree-stage svg{display:none}.tree-node,.tree-node.root,.tree-node.branch,.tree-node.ui,.tree-node.tests,.tree-node.docs{position:relative;top:auto;right:auto;left:auto;width:100%;margin:0 0 34px;transform:none}.tree-node:not(:last-child)::after{content:'↓';position:absolute;left:50%;bottom:-28px;color:var(--gold)}.tree-node:hover,.tree-node.active,.tree-node.root:hover,.tree-node.root.active,.tree-node.tests:hover,.tree-node.tests.active{transform:translateY(-2px)}.tree-detail{grid-template-columns:1fr}.tree-detail p,.tree-detail code{grid-column:auto}.skill-explorer{grid-template-columns:1fr}.route-detail{grid-template-columns:70px 1fr}.route-meter{width:56px;height:70px}.skill-index{grid-template-columns:1fr}.skill-index button{min-height:78px}.common-skill-detail{min-height:0;padding:30px 24px}.common-skill-notes{grid-template-columns:1fr}.common-skill-notes>div:first-child{grid-column:auto}.skill-loadout{grid-template-columns:1fr}.skill-loadout>div{line-height:2}.skill-loadout i{margin-inline:4px}}
+@media(max-width:800px){.worker-detail{grid-template-columns:1fr}.worktrees{display:block}.worktree-intro{margin-bottom:40px}.tree-lab{box-shadow:9px 9px 0 #081621}.route-table button{min-width:620px}.skill-explorer{grid-template-columns:1fr 1fr}.builder-intro,.catalog-intro{grid-template-columns:1fr;gap:20px}.builder-workbench{grid-template-columns:1fr}.builder-steps{grid-template-columns:1fr 1fr;grid-template-rows:none}.builder-artifact{grid-column:auto}.skill-deck{grid-template-columns:1fr}.skill-index{grid-template-columns:1fr 1fr;grid-template-rows:none}.common-skill-detail{min-height:600px}.common-skill-notes{grid-template-columns:1fr 1fr}.common-skill-notes>div:first-child{grid-column:1/-1}}
+@media(max-width:600px){.tree-stage{height:auto;min-height:560px;padding:24px}.tree-stage svg{display:none}.tree-node,.tree-node.root,.tree-node.branch,.tree-node.ui,.tree-node.tests,.tree-node.docs{position:relative;top:auto;right:auto;left:auto;width:100%;margin:0 0 34px;transform:none}.tree-node:not(:last-child)::after{content:'↓';position:absolute;left:50%;bottom:-28px;color:var(--gold)}.tree-node:hover,.tree-node.active,.tree-node.root:hover,.tree-node.root.active,.tree-node.tests:hover,.tree-node.tests.active{transform:translateY(-2px)}.tree-detail{grid-template-columns:1fr}.tree-detail p,.tree-detail code{grid-column:auto}.skill-explorer{grid-template-columns:1fr}.route-detail{grid-template-columns:70px 1fr}.route-meter{width:56px;height:70px}.builder-steps{grid-template-columns:1fr}.builder-steps button{min-height:78px}.builder-detail{padding:28px 24px}.builder-detail footer{grid-template-columns:1fr}.builder-artifact{grid-template-columns:1fr}.builder-artifact .artifact-head{grid-column:auto}.artifact-command{border-left:0;border-top:1px solid #344c5d}.builder-loop{grid-template-columns:1fr}.builder-loop>div{line-height:2}.builder-loop i{margin-inline:4px}.skill-index{grid-template-columns:1fr}.skill-index button{min-height:78px}.common-skill-detail{min-height:0;padding:30px 24px}.common-skill-notes{grid-template-columns:1fr}.common-skill-notes>div:first-child{grid-column:auto}.skill-loadout{grid-template-columns:1fr}.skill-loadout>div{line-height:2}.skill-loadout i{margin-inline:4px}}
 @media(prefers-reduced-motion:reduce){.worker-card,.tree-node,.route-meter span{transition:none}.reading-progress span{transition:none}}
diff --git a/scripts/verify.mjs b/scripts/verify.mjs
index 849af90..0248dfd 100644
--- a/scripts/verify.mjs
+++ b/scripts/verify.mjs
@@ -6,8 +6,8 @@ const refs = read('docs/references/README.md');
 const additional = read('docs/references/additional-reading.md');
 for (const url of ['https://code.claude.com/docs/en/sub-agents','https://code.claude.com/docs/en/skills','https://code.claude.com/docs/en/worktrees','https://git-scm.com/docs/git-worktree.html','https://developers.openai.com/codex/skills']) if (!refs.includes(url)) throw new Error(`missing reference ${url}`);
 console.log('content verification passed');
-for (const token of ['data-phase="plan"','data-phase="build"','data-phase="review"','data-tree="main"','data-tree="ui"','data-worker="ui"','data-route="plan"','data-skill-file="skill"','data-common-skill="ponytail"','data-common-skill="caveman"','data-common-skill="unlazy"','additional-reading.md','role="tablist"','<table']) if (!html.includes(token)) throw new Error(`missing content ${token}`);
-for (const token of ['const phases','addEventListener','render(\'plan\')','renderTree','renderWorker','renderRoute','renderSkillFile','renderCommonSkill']) if (!js.includes(token)) throw new Error(`missing interaction ${token}`);
+for (const token of ['data-phase="plan"','data-phase="build"','data-phase="review"','data-tree="main"','data-tree="ui"','data-worker="ui"','data-route="plan"','data-skill-file="skill"','data-skill-step="observe"','data-skill-step="validate"','data-common-skill="ponytail"','data-common-skill="caveman"','data-common-skill="unlazy"','additional-reading.md','role="tablist"','<table']) if (!html.includes(token)) throw new Error(`missing content ${token}`);
+for (const token of ['const phases','addEventListener','render(\'plan\')','renderTree','renderWorker','renderRoute','renderSkillFile','renderSkillWorkflow','renderCommonSkill']) if (!js.includes(token)) throw new Error(`missing interaction ${token}`);
 for (const token of ['medium.com','anthropic.com/engineering','openai.com/business','git-scm.com/docs/git-worktree']) if (!additional.includes(token)) throw new Error(`missing additional source ${token}`);
 if ((additional.match(/^### \d+\./gm) || []).length < 5) throw new Error('fewer than five additional readings');
 console.log('interaction verification passed');