refactor(ship): carve into skeleton + on-demand sections (Claude) (T9)

ship/SKILL.md drops 167KB → 68.7KB (~59% of the always-loaded skill) by moving
8 prose-heavy steps into ship/sections/*.md, read on demand:
tests, test-coverage, plan-completion, review-army, greptile, adversarial,
changelog, pr-body. Step 12's version logic now calls the tested
gstack-version-bump CLI instead of inline bash.

Claude-first (S2): {{SECTION:id}} emits a STOP-Read pointer on Claude (skeleton +
generated section files) and INLINES the content on every other host, so external
hosts keep the full monolith — verified factory at 162KB with no sections dir.
{{SECTION_INDEX:ship}} renders the situation→section table from the PASSIVE
manifest (CM2 / v2_PLAN.md:663); required-reads live only in test fixtures.
Multi-pass resolve expands inlined sections' own resolvers.

Parity: ship invariant flipped to sectioned (union content checks + maxSkeletonBytes
asserts the shrink). Carve-fallout fixed across gen-skill-docs/skill-validation/
golden/plan-completion/#1539/size-budget tests via skeleton+sections union reads.
Free suite green except the pre-existing investigate parity drift.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/resolvers/index.ts

@@ -34,6 +34,7 @@ import { generateGBrainContextLoad, generateGBrainSaveResults } from './gbrain';
 import { generateQuestionPreferenceCheck, generateQuestionLog, generateInlineTuneFeedback } from './question-tuning';
 import { generateMakePdfSetup } from './make-pdf';
 import { generateTasksSectionEmit, generateTasksSectionAggregate } from './tasks-section';
+import { SECTION, SECTION_INDEX } from './sections';
 
 export const RESOLVERS: Record<string, ResolverValue> = {
   SLUG_EVAL: generateSlugEval,
@@ -92,4 +93,6 @@ export const RESOLVERS: Record<string, ResolverValue> = {
   MAKE_PDF_SETUP: generateMakePdfSetup,
   TASKS_SECTION_EMIT: generateTasksSectionEmit,
   TASKS_SECTION_AGGREGATE: generateTasksSectionAggregate,
+  SECTION,
+  SECTION_INDEX,
 };

scripts/resolvers/sections.ts

@@ -0,0 +1,96 @@
+/**
+ * Section resolvers (v2 plan T9, Claude-first carve).
+ *
+ * A carved skill keeps its prose-heavy steps in `<skill>/sections/<id>.md`, read
+ * on demand. The SAME template ships to every host, so these resolvers make the
+ * carve host-aware:
+ *
+ *  - On CLAUDE: {{SECTION:id}} emits a STOP-Read pointer to the generated section
+ *    file (the skeleton), and the section .md is generated + installed separately.
+ *  - On every OTHER host: {{SECTION:id}} INLINES the section template's content,
+ *    so external hosts keep the full monolith ship skill (no section files, no
+ *    host-portable-path problem). Inlined content keeps its own {{RESOLVER}}
+ *    tokens, which the generator's multi-pass resolve expands.
+ *
+ * {{SECTION_INDEX:skill}} renders the situation→section table from the PASSIVE
+ * manifest on Claude (empty on other hosts — they have no sections). The manifest
+ * is the single source of id/file/title/trigger text (CM2; v2_PLAN.md:663).
+ */
+
+import * as fs from 'fs';
+import * as path from 'path';
+import type { ResolverFn, TemplateContext } from './types';
+
+const ROOT = path.resolve(import.meta.dir, '..', '..');
+
+interface SectionEntry {
+  id: string;
+  file: string;
+  title: string;
+  trigger: string;
+}
+interface SectionManifest {
+  skill: string;
+  sections: SectionEntry[];
+}
+
+function loadManifest(skill: string): SectionManifest {
+  const p = path.join(ROOT, skill, 'sections', 'manifest.json');
+  const raw = fs.readFileSync(p, 'utf-8');
+  return JSON.parse(raw) as SectionManifest;
+}
+
+function findSection(skill: string, id: string): SectionEntry {
+  const entry = loadManifest(skill).sections.find(s => s.id === id);
+  if (!entry) {
+    throw new Error(`{{SECTION:${id}}} — no section "${id}" in ${skill}/sections/manifest.json`);
+  }
+  return entry;
+}
+
+/**
+ * {{SECTION:id}} — pointer on Claude, inline on other hosts.
+ * Claude path uses the stable gstack-root install (`{skillRoot}/{skill}/sections/`),
+ * which always exists, instead of a naked relative path (Codex outside-voice #7).
+ */
+export const SECTION: ResolverFn = (ctx: TemplateContext, args?: string[]): string => {
+  const id = args?.[0];
+  if (!id) throw new Error('{{SECTION:id}} requires a section id');
+  const entry = findSection(ctx.skillName, id);
+
+  if (ctx.host === 'claude') {
+    const sectionPath = `${ctx.paths.skillRoot}/${ctx.skillName}/sections/${entry.file}`;
+    return [
+      `> **STOP.** Before ${entry.trigger}, Read \`${sectionPath}\` and execute it`,
+      `> in full. Do not work from memory — that section is the source of truth for this step.`,
+    ].join('\n');
+  }
+
+  // Non-Claude hosts inline the section template content (monolith preserved).
+  // Inner {{RESOLVER}} tokens are expanded by the generator's multi-pass resolve.
+  const tmplPath = path.join(ROOT, ctx.skillName, 'sections', `${entry.file}.tmpl`);
+  return fs.readFileSync(tmplPath, 'utf-8').trimEnd();
+};
+
+/**
+ * {{SECTION_INDEX:skill}} — situation→section table from the passive manifest.
+ * Claude only; other hosts inline everything so an index would be noise.
+ */
+export const SECTION_INDEX: ResolverFn = (ctx: TemplateContext, args?: string[]): string => {
+  if (ctx.host !== 'claude') return '';
+  const skill = args?.[0] ?? ctx.skillName;
+  const manifest = loadManifest(skill);
+  const lines: string[] = [
+    '## Section index — Read each section when its situation applies',
+    '',
+    'This skill is a decision-tree skeleton. The steps below point to on-demand',
+    'sections. Read a section in full before doing its step; do not work from memory.',
+    '',
+    '| When | Read this section |',
+    '|------|-------------------|',
+  ];
+  for (const s of manifest.sections) {
+    lines.push(`| ${s.trigger} | \`sections/${s.file}\` |`);
+  }
+  return lines.join('\n');
+};