diff --git a/src/core/skillpack/bundle.ts b/src/core/skillpack/bundle.ts
index 8cc3eb697..ec1130bc5 100644
--- a/src/core/skillpack/bundle.ts
+++ b/src/core/skillpack/bundle.ts
@@ -10,6 +10,8 @@
 import { existsSync, readFileSync, statSync, readdirSync } from 'fs';
 import { join, dirname, isAbsolute, resolve } from 'path';
 
+import { parseMarkdown } from '../markdown.ts';
+
 export interface BundleManifest {
   name: string;
   version: string;
@@ -224,3 +226,240 @@ export function pathSlug(relPath: string): string {
 export function bundledSkillSlugs(manifest: BundleManifest): string[] {
   return manifest.skills.map(pathSlug).sort();
 }
+
+// ---------------------------------------------------------------------------
+// Frontmatter `sources:` — paired source files declared by a skill (v0.33+)
+// ---------------------------------------------------------------------------
+//
+// A skill that ships paired implementation (e.g. book-mirror's
+// `src/commands/book-mirror.ts`) declares it in its SKILL.md frontmatter:
+//
+//   ---
+//   name: book-mirror
+//   sources:
+//     - src/commands/book-mirror.ts
+//   ---
+//
+// The bundler reads this on every enumerate; scaffold copies the paired
+// files alongside the skill markdown. Single source of truth co-located
+// with the skill — no parallel manifest in openclaw.plugin.json.
+
+/** A skill's declared paired-source paths (repo-relative). */
+export interface SkillSources {
+  slug: string;
+  sources: string[];
+}
+
+/**
+ * Read `<gbrainRoot>/<skillRel>/SKILL.md` and return its `sources:`
+ * frontmatter array. Empty array when absent or empty.
+ *
+ * Fail-loud validation (throws `BundleError` with `manifest_malformed`):
+ *   - every entry must be a string
+ *   - relative path only (no leading `/`, no `../` traversal)
+ *   - every referenced file must exist under `<gbrainRoot>`
+ *
+ * Skills without `sources:` declared, or with `sources: []`, return an
+ * empty array (no validation work performed).
+ */
+export function loadSkillSources(gbrainRoot: string, skillRel: string): SkillSources {
+  const slug = pathSlug(skillRel);
+  const skillMd = join(gbrainRoot, skillRel, 'SKILL.md');
+  if (!existsSync(skillMd)) {
+    // Some bundled "skills" are markdown-only without a SKILL.md (rare,
+    // e.g. shared-conventions directories). Treat as no sources.
+    return { slug, sources: [] };
+  }
+  let content: string;
+  try {
+    content = readFileSync(skillMd, 'utf-8');
+  } catch (err) {
+    throw new BundleError(
+      `Failed to read ${skillMd}: ${(err as Error).message}`,
+      'manifest_malformed',
+    );
+  }
+  let parsed;
+  try {
+    parsed = parseMarkdown(content, skillMd);
+  } catch (err) {
+    throw new BundleError(
+      `${skillMd}: frontmatter parse error — ${(err as Error).message}`,
+      'manifest_malformed',
+    );
+  }
+  const raw = parsed.frontmatter.sources;
+  if (raw === undefined || raw === null) {
+    return { slug, sources: [] };
+  }
+  if (!Array.isArray(raw)) {
+    throw new BundleError(
+      `${skillMd}: frontmatter \`sources:\` must be an array of strings`,
+      'manifest_malformed',
+    );
+  }
+  const sources: string[] = [];
+  for (const entry of raw) {
+    if (typeof entry !== 'string') {
+      throw new BundleError(
+        `${skillMd}: every entry in frontmatter \`sources:\` must be a string`,
+        'manifest_malformed',
+      );
+    }
+    if (entry.length === 0) {
+      throw new BundleError(
+        `${skillMd}: empty string in frontmatter \`sources:\``,
+        'manifest_malformed',
+      );
+    }
+    if (isAbsolute(entry)) {
+      throw new BundleError(
+        `${skillMd}: frontmatter \`sources:\` entry "${entry}" must be relative to the repo root, not absolute`,
+        'manifest_malformed',
+      );
+    }
+    if (entry.includes('..')) {
+      throw new BundleError(
+        `${skillMd}: frontmatter \`sources:\` entry "${entry}" contains \`..\` traversal — refusing for safety`,
+        'manifest_malformed',
+      );
+    }
+    const abs = join(gbrainRoot, entry);
+    if (!existsSync(abs)) {
+      throw new BundleError(
+        `${skillMd}: frontmatter \`sources:\` declares "${entry}" but the file is missing from ${gbrainRoot}`,
+        'manifest_malformed',
+      );
+    }
+    sources.push(entry);
+  }
+  return { slug, sources };
+}
+
+// ---------------------------------------------------------------------------
+// ScaffoldEntry — workspace-rooted, includes paired-source files
+// ---------------------------------------------------------------------------
+
+/**
+ * Like `BundleEntry`, but `relWorkspaceTarget` is rooted at the target
+ * workspace (not the target skills dir). Lets scaffold place paired
+ * source files at their mirror path (`src/commands/foo.ts`) alongside
+ * the skill markdown (`skills/<slug>/SKILL.md`).
+ */
+export interface ScaffoldEntry {
+  source: string;
+  relWorkspaceTarget: string;
+  sharedDep: boolean;
+  /** Whether from a skill's frontmatter `sources:` declaration. */
+  pairedSource: boolean;
+}
+
+/**
+ * Enumerate every file the new scaffold model would copy. Workspace-
+ * rooted targets:
+ *   - skill files     → `skills/<slug>/<rel>`
+ *   - shared deps     → `skills/<rel>`
+ *   - paired sources  → `<source>` (e.g. `src/commands/book-mirror.ts`)
+ *
+ * Fail-loud on missing declared paired sources via `loadSkillSources`.
+ */
+export function enumerateScaffoldEntries(opts: EnumerateOptions): ScaffoldEntry[] {
+  const { gbrainRoot, skillSlug, manifest } = opts;
+  const entries: ScaffoldEntry[] = [];
+
+  const skillsToIncludePaths = skillSlug
+    ? manifest.skills.filter(p => pathSlug(p) === skillSlug)
+    : manifest.skills;
+
+  if (skillSlug && skillsToIncludePaths.length === 0) {
+    throw new BundleError(
+      `Skill '${skillSlug}' is not listed in openclaw.plugin.json#skills`,
+      'skill_not_found',
+    );
+  }
+
+  // 1. Skill files — every file under `<gbrainRoot>/skills/<slug>/`.
+  //    relWorkspaceTarget = `skills/<slug>/<rest>` (workspace-rooted).
+  for (const rel of skillsToIncludePaths) {
+    const abs = join(gbrainRoot, rel);
+    if (!existsSync(abs)) {
+      throw new BundleError(
+        `Bundle lists '${rel}' but the path does not exist in ${gbrainRoot}`,
+        'skill_not_found',
+      );
+    }
+    walkScaffoldFiles(abs, rel, entries, false, false);
+  }
+
+  // 2. Paired sources — declared via each skill's frontmatter `sources:`.
+  //    relWorkspaceTarget = `<source>` (already workspace-relative).
+  for (const rel of skillsToIncludePaths) {
+    const { sources } = loadSkillSources(gbrainRoot, rel);
+    for (const src of sources) {
+      entries.push({
+        source: join(gbrainRoot, src),
+        relWorkspaceTarget: src,
+        sharedDep: false,
+        pairedSource: true,
+      });
+    }
+  }
+
+  // 3. Shared deps — convention files etc. relWorkspaceTarget = `skills/<rest>`.
+  for (const dep of manifest.shared_deps) {
+    const abs = join(gbrainRoot, dep);
+    if (!existsSync(abs)) continue; // missing shared dep is a warning, not fatal
+    let stat;
+    try {
+      stat = statSync(abs);
+    } catch {
+      continue;
+    }
+    if (stat.isDirectory()) {
+      walkScaffoldFiles(abs, dep, entries, true, false);
+    } else if (stat.isFile()) {
+      entries.push({
+        source: abs,
+        relWorkspaceTarget: dep,
+        sharedDep: true,
+        pairedSource: false,
+      });
+    }
+  }
+
+  return entries;
+}
+
+function walkScaffoldFiles(
+  absDir: string,
+  workspaceRelPrefix: string,
+  out: ScaffoldEntry[],
+  sharedDep: boolean,
+  pairedSource: boolean,
+): void {
+  let entries: string[];
+  try {
+    entries = readdirSync(absDir);
+  } catch {
+    return;
+  }
+  for (const e of entries) {
+    const abs = join(absDir, e);
+    let stat;
+    try {
+      stat = statSync(abs);
+    } catch {
+      continue;
+    }
+    if (stat.isDirectory()) {
+      walkScaffoldFiles(abs, join(workspaceRelPrefix, e), out, sharedDep, pairedSource);
+    } else if (stat.isFile()) {
+      out.push({
+        source: abs,
+        relWorkspaceTarget: join(workspaceRelPrefix, e),
+        sharedDep,
+        pairedSource,
+      });
+    }
+  }
+}
diff --git a/src/core/skillpack/scaffold.ts b/src/core/skillpack/scaffold.ts
new file mode 100644
index 000000000..53f43117b
--- /dev/null
+++ b/src/core/skillpack/scaffold.ts
@@ -0,0 +1,149 @@
+/**
+ * skillpack/scaffold.ts — `gbrain skillpack scaffold <name>`.
+ *
+ * One-time, additive copy of a bundled skill into a host workspace. The
+ * file-copy primitive is shared with harvest (host→gbrain) via
+ * `copyArtifacts`. The bundle enumeration is shared with the bundle
+ * manifest itself via `enumerateScaffoldEntries` — which now also picks
+ * up paired source files declared in each skill's frontmatter
+ * `sources:` array.
+ *
+ * Contracts (the new model):
+ *   1. **No managed-block writes.** The host's RESOLVER.md / AGENTS.md
+ *      stays untouched. Routing happens via each skill's frontmatter
+ *      `triggers:` array, which downstream agents walk at runtime.
+ *   2. **Refuses to overwrite existing files.** Once a file lands, the
+ *      user owns it. To update, run `gbrain skillpack reference <name>`
+ *      and decide.
+ *   3. **Partial-state policy.** When `skills/<slug>/` already exists
+ *      but the skill's frontmatter declares paired `sources:` that are
+ *      missing on host, scaffold copies the missing paired files into
+ *      place. Existing files are still preserved. Closes the
+ *      "skill shipped, later gained a paired source" gap.
+ *   4. **No lockfile, no cumulative-slugs receipt, no `--all` prune.**
+ *      All deleted. The new model lets the user own the files; nothing
+ *      to lock or to track.
+ */
+
+import { join } from 'path';
+
+import { copyArtifacts, walkSourceDir } from './copy.ts';
+import type { CopyItem } from './copy.ts';
+import { enumerateScaffoldEntries, loadBundleManifest } from './bundle.ts';
+import type { ScaffoldEntry } from './bundle.ts';
+
+export interface ScaffoldOptions {
+  /** Absolute path to gbrain repo root (source-of-truth bundle). */
+  gbrainRoot: string;
+  /** Absolute path to the target workspace (e.g. ~/git/wintermute). */
+  targetWorkspace: string;
+  /** Single skill slug, or `null` for --all. */
+  skillSlug: string | null;
+  /** Dry-run: validate + report; no writes. */
+  dryRun?: boolean;
+}
+
+export type ScaffoldOutcome = 'wrote_new' | 'skipped_existing';
+
+export interface ScaffoldFileResult {
+  source: string;
+  target: string;
+  outcome: ScaffoldOutcome;
+  sharedDep: boolean;
+  pairedSource: boolean;
+}
+
+export interface ScaffoldResult {
+  dryRun: boolean;
+  files: ScaffoldFileResult[];
+  summary: {
+    wroteNew: number;
+    skippedExisting: number;
+    /** Among `wroteNew`, how many were paired source files (frontmatter
+     *  `sources:`) — useful for partial-state cases where the skill
+     *  already existed but a paired source was missing. */
+    pairedSourcesWritten: number;
+  };
+}
+
+export class ScaffoldError extends Error {
+  constructor(
+    message: string,
+    public code: 'bundle_error' | 'target_missing' | 'unknown_skill',
+  ) {
+    super(message);
+    this.name = 'ScaffoldError';
+  }
+}
+
+/**
+ * Run a scaffold. Loads the bundle manifest, enumerates every file the
+ * skill (or all skills when slug=null) would land, and copies them into
+ * the target workspace at their mirror paths. Refuses to overwrite any
+ * existing file.
+ *
+ * Idempotent: re-running on a fully-scaffolded workspace is a no-op.
+ *
+ * Partial-state handled naturally: if `skills/<slug>/` exists but a
+ * declared paired source is missing, the missing item is copied while
+ * the present ones are skipped.
+ */
+export function runScaffold(opts: ScaffoldOptions): ScaffoldResult {
+  const manifest = loadBundleManifest(opts.gbrainRoot);
+
+  // enumerateScaffoldEntries throws BundleError if the slug is unknown
+  // or if any declared paired source is missing on disk. Surface those
+  // as ScaffoldError with the matching code for caller ergonomics.
+  let entries: ScaffoldEntry[];
+  try {
+    entries = enumerateScaffoldEntries({
+      gbrainRoot: opts.gbrainRoot,
+      skillSlug: opts.skillSlug ?? undefined,
+      manifest,
+    });
+  } catch (err) {
+    const e = err as Error & { code?: string };
+    if (e.code === 'skill_not_found') {
+      throw new ScaffoldError(e.message, 'unknown_skill');
+    }
+    throw new ScaffoldError(e.message, 'bundle_error');
+  }
+
+  // Map ScaffoldEntry → CopyItem (workspace-rooted target path).
+  const items: CopyItem[] = entries.map(e => ({
+    source: e.source,
+    target: join(opts.targetWorkspace, e.relWorkspaceTarget),
+  }));
+
+  // Shared copy primitive. Refuses to overwrite existing files; no
+  // symlink check or path confinement (the scaffold source is gbrain's
+  // own trusted bundle).
+  const copyResult = copyArtifacts(items, { dryRun: opts.dryRun });
+
+  // Stitch outcomes back to ScaffoldEntry metadata so callers can tell
+  // sharedDep / pairedSource per file.
+  const files: ScaffoldFileResult[] = copyResult.files.map((f, i) => ({
+    source: f.source,
+    target: f.target,
+    outcome: f.outcome,
+    sharedDep: entries[i].sharedDep,
+    pairedSource: entries[i].pairedSource,
+  }));
+
+  return {
+    dryRun: copyResult.dryRun,
+    files,
+    summary: {
+      wroteNew: copyResult.summary.wroteNew,
+      skippedExisting: copyResult.summary.skippedExisting,
+      pairedSourcesWritten: files.filter(
+        f => f.outcome === 'wrote_new' && f.pairedSource,
+      ).length,
+    },
+  };
+}
+
+// Re-export the public symbols from copy.ts so callers can `import
+// { walkSourceDir } from 'scaffold.ts'` if they prefer one entry point.
+// (Not load-bearing — direct imports from copy.ts are equally fine.)
+export { copyArtifacts, walkSourceDir };
diff --git a/test/skillpack-frontmatter-sources.test.ts b/test/skillpack-frontmatter-sources.test.ts
new file mode 100644
index 000000000..4679fa753
--- /dev/null
+++ b/test/skillpack-frontmatter-sources.test.ts
@@ -0,0 +1,130 @@
+/**
+ * Tests for `loadSkillSources` in src/core/skillpack/bundle.ts —
+ * the per-skill paired-source declaration via SKILL.md frontmatter
+ * `sources:` array (v0.33+, D2).
+ *
+ * Pins the fail-loud validation contract:
+ *   - empty/absent `sources:` → empty array, no error
+ *   - non-string entry → BundleError(manifest_malformed)
+ *   - absolute path → BundleError
+ *   - `..` traversal → BundleError
+ *   - declared file missing on disk → BundleError
+ */
+
+import { describe, expect, it, afterEach } from 'bun:test';
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+
+import { BundleError, loadSkillSources } from '../src/core/skillpack/bundle.ts';
+
+const created: string[] = [];
+afterEach(() => {
+  while (created.length) {
+    const p = created.pop()!;
+    try {
+      rmSync(p, { recursive: true, force: true });
+    } catch {}
+  }
+});
+
+function scratchGbrain(): string {
+  const root = mkdtempSync(join(tmpdir(), 'fms-gbrain-'));
+  created.push(root);
+  mkdirSync(join(root, 'src', 'commands'), { recursive: true });
+  mkdirSync(join(root, 'skills', 'sample'), { recursive: true });
+  return root;
+}
+
+function writeSkill(root: string, name: string, frontmatter: string): void {
+  const dir = join(root, 'skills', name);
+  mkdirSync(dir, { recursive: true });
+  writeFileSync(join(dir, 'SKILL.md'), `---\n${frontmatter}\n---\n# ${name}\n`);
+}
+
+describe('loadSkillSources', () => {
+  it('returns empty array when frontmatter has no `sources:` field', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'plain', 'name: plain\nversion: 0.1.0');
+
+    const out = loadSkillSources(root, 'skills/plain');
+    expect(out.slug).toBe('plain');
+    expect(out.sources).toEqual([]);
+  });
+
+  it('returns empty array when SKILL.md is missing (shared-conventions dirs)', () => {
+    const root = scratchGbrain();
+    mkdirSync(join(root, 'skills', 'no-md-dir'));
+    writeFileSync(join(root, 'skills', 'no-md-dir', 'README.md'), 'no skill here');
+
+    const out = loadSkillSources(root, 'skills/no-md-dir');
+    expect(out.sources).toEqual([]);
+  });
+
+  it('reads a valid `sources:` array and returns repo-relative paths', () => {
+    const root = scratchGbrain();
+    writeFileSync(join(root, 'src', 'commands', 'demo.ts'), '// stub');
+    writeSkill(
+      root,
+      'demo',
+      'name: demo\nsources:\n  - src/commands/demo.ts',
+    );
+
+    const out = loadSkillSources(root, 'skills/demo');
+    expect(out.sources).toEqual(['src/commands/demo.ts']);
+  });
+
+  it('returns empty array when `sources: []` is explicitly empty', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'empty-sources', 'name: empty-sources\nsources: []');
+
+    const out = loadSkillSources(root, 'skills/empty-sources');
+    expect(out.sources).toEqual([]);
+  });
+
+  it('throws BundleError when `sources:` is not an array', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'bad', 'name: bad\nsources: not-an-array');
+
+    expect(() => loadSkillSources(root, 'skills/bad')).toThrow(BundleError);
+  });
+
+  it('throws when an entry is not a string', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'bad', 'name: bad\nsources:\n  - 42');
+
+    expect(() => loadSkillSources(root, 'skills/bad')).toThrow(BundleError);
+  });
+
+  it('throws on absolute paths', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'bad', 'name: bad\nsources:\n  - /etc/passwd');
+
+    expect(() => loadSkillSources(root, 'skills/bad')).toThrow(/absolute/);
+  });
+
+  it('throws on `..` traversal', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'bad', 'name: bad\nsources:\n  - ../other-repo/src/leak.ts');
+
+    expect(() => loadSkillSources(root, 'skills/bad')).toThrow(/traversal/);
+  });
+
+  it('throws when a declared source file is missing on disk', () => {
+    const root = scratchGbrain();
+    writeSkill(
+      root,
+      'gone',
+      'name: gone\nsources:\n  - src/commands/never-built.ts',
+    );
+
+    expect(() => loadSkillSources(root, 'skills/gone')).toThrow(/missing from/);
+  });
+
+  it('throws on empty string entries', () => {
+    const root = scratchGbrain();
+    writeSkill(root, 'bad', 'name: bad\nsources:\n  - ""');
+
+    expect(() => loadSkillSources(root, 'skills/bad')).toThrow(BundleError);
+  });
+});
diff --git a/test/skillpack-scaffold.test.ts b/test/skillpack-scaffold.test.ts
new file mode 100644
index 000000000..b42d18d9e
--- /dev/null
+++ b/test/skillpack-scaffold.test.ts
@@ -0,0 +1,274 @@
+/**
+ * Tests for src/core/skillpack/scaffold.ts — the new (v0.33) scaffold
+ * model that replaces the managed-block installer.
+ *
+ * Pins:
+ *   - happy path: skill files + shared deps + paired sources land at
+ *     workspace-rooted paths
+ *   - refuses to overwrite existing files (the user owns them)
+ *   - partial-state policy: skill present, paired source missing → fill
+ *   - --all (skillSlug: null) installs every bundled skill
+ *   - dry-run reports outcomes but writes nothing
+ *   - IRON-RULE regressions: no managed block, no lockfile, no
+ *     cumulative-slugs receipt, no .gbrain-skillpack.lock file
+ */
+
+import { describe, expect, it, afterEach } from 'bun:test';
+import { existsSync, mkdirSync, mkdtempSync, readFileSync, readdirSync, rmSync, writeFileSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+
+import { runScaffold, ScaffoldError } from '../src/core/skillpack/scaffold.ts';
+
+const created: string[] = [];
+afterEach(() => {
+  while (created.length) {
+    const p = created.pop()!;
+    try {
+      rmSync(p, { recursive: true, force: true });
+    } catch {}
+  }
+});
+
+interface GbrainFixture {
+  gbrainRoot: string;
+}
+
+function scratchGbrain(opts: { withPairedSource?: boolean } = {}): GbrainFixture {
+  const root = mkdtempSync(join(tmpdir(), 'sp-scaffold-gbrain-'));
+  created.push(root);
+  mkdirSync(join(root, 'src', 'cli.ts').replace('cli.ts', ''), { recursive: true });
+  writeFileSync(join(root, 'src', 'cli.ts'), '// stub');
+  mkdirSync(join(root, 'src', 'commands'), { recursive: true });
+
+  // book-mirror with paired source
+  mkdirSync(join(root, 'skills', 'book-mirror'), { recursive: true });
+  const bmFm = opts.withPairedSource
+    ? '---\nname: book-mirror\ntriggers:\n  - bm trigger\nsources:\n  - src/commands/book-mirror.ts\n---\n# book-mirror\n'
+    : '---\nname: book-mirror\ntriggers:\n  - bm trigger\n---\n# book-mirror\n';
+  writeFileSync(join(root, 'skills', 'book-mirror', 'SKILL.md'), bmFm);
+  writeFileSync(join(root, 'skills', 'book-mirror', 'routing-eval.jsonl'), '{"intent":"bm"}\n');
+
+  if (opts.withPairedSource) {
+    writeFileSync(join(root, 'src', 'commands', 'book-mirror.ts'), '// real impl\n');
+  }
+
+  // plain second skill (no paired source)
+  mkdirSync(join(root, 'skills', 'query'), { recursive: true });
+  writeFileSync(
+    join(root, 'skills', 'query', 'SKILL.md'),
+    '---\nname: query\ntriggers:\n  - q trigger\n---\n# query\n',
+  );
+
+  // shared deps
+  mkdirSync(join(root, 'skills', 'conventions'), { recursive: true });
+  writeFileSync(join(root, 'skills', 'conventions', 'quality.md'), '# quality\n');
+  writeFileSync(join(root, 'skills', '_brain-filing-rules.md'), '# filing rules\n');
+
+  // bundle manifest
+  writeFileSync(
+    join(root, 'openclaw.plugin.json'),
+    JSON.stringify(
+      {
+        name: 'gbrain-test',
+        version: '0.33.0-test',
+        skills: ['skills/book-mirror', 'skills/query'],
+        shared_deps: ['skills/conventions', 'skills/_brain-filing-rules.md'],
+      },
+      null,
+      2,
+    ),
+  );
+  return { gbrainRoot: root };
+}
+
+function scratchWorkspace(): string {
+  const ws = mkdtempSync(join(tmpdir(), 'sp-scaffold-ws-'));
+  created.push(ws);
+  return ws;
+}
+
+describe('runScaffold — happy path', () => {
+  it('copies a single skill plus shared deps to the workspace', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    const result = runScaffold({
+      gbrainRoot,
+      targetWorkspace: ws,
+      skillSlug: 'book-mirror',
+    });
+
+    expect(result.summary.wroteNew).toBeGreaterThan(0);
+    expect(existsSync(join(ws, 'skills', 'book-mirror', 'SKILL.md'))).toBe(true);
+    expect(existsSync(join(ws, 'skills', 'book-mirror', 'routing-eval.jsonl'))).toBe(true);
+    expect(existsSync(join(ws, 'skills', 'conventions', 'quality.md'))).toBe(true);
+    expect(existsSync(join(ws, 'skills', '_brain-filing-rules.md'))).toBe(true);
+  });
+
+  it('copies paired source files declared in frontmatter `sources:`', () => {
+    const { gbrainRoot } = scratchGbrain({ withPairedSource: true });
+    const ws = scratchWorkspace();
+
+    const result = runScaffold({
+      gbrainRoot,
+      targetWorkspace: ws,
+      skillSlug: 'book-mirror',
+    });
+
+    expect(existsSync(join(ws, 'src', 'commands', 'book-mirror.ts'))).toBe(true);
+    expect(readFileSync(join(ws, 'src', 'commands', 'book-mirror.ts'), 'utf-8')).toBe(
+      '// real impl\n',
+    );
+    expect(result.summary.pairedSourcesWritten).toBe(1);
+  });
+
+  it('--all (skillSlug: null) installs every bundled skill', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: null });
+
+    expect(existsSync(join(ws, 'skills', 'book-mirror', 'SKILL.md'))).toBe(true);
+    expect(existsSync(join(ws, 'skills', 'query', 'SKILL.md'))).toBe(true);
+  });
+});
+
+describe('runScaffold — refuses to overwrite (user owns the files)', () => {
+  it('re-running is idempotent (every file skipped_existing)', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+    const second = runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+
+    expect(second.summary.wroteNew).toBe(0);
+    expect(second.summary.skippedExisting).toBeGreaterThan(0);
+    expect(second.files.every(f => f.outcome === 'skipped_existing')).toBe(true);
+  });
+
+  it('preserves local edits to a scaffolded file', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+    writeFileSync(join(ws, 'skills', 'book-mirror', 'SKILL.md'), 'MY EDITS');
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+    expect(readFileSync(join(ws, 'skills', 'book-mirror', 'SKILL.md'), 'utf-8')).toBe('MY EDITS');
+  });
+
+  it('does not overwrite existing shared-dep files', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    mkdirSync(join(ws, 'skills', 'conventions'), { recursive: true });
+    writeFileSync(join(ws, 'skills', 'conventions', 'quality.md'), 'USER OWNS THIS');
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+    expect(readFileSync(join(ws, 'skills', 'conventions', 'quality.md'), 'utf-8')).toBe(
+      'USER OWNS THIS',
+    );
+  });
+});
+
+describe('runScaffold — partial-state policy (F-CDX-6)', () => {
+  it('skill dir exists but paired source missing → copies the paired source only', () => {
+    const { gbrainRoot } = scratchGbrain({ withPairedSource: true });
+    const ws = scratchWorkspace();
+
+    // First, scaffold without the paired source declared (simulating "skill
+    // shipped before sources: was added"). We model this by pre-creating
+    // the skill files manually:
+    mkdirSync(join(ws, 'skills', 'book-mirror'), { recursive: true });
+    writeFileSync(join(ws, 'skills', 'book-mirror', 'SKILL.md'), '# pre-existing skill content\n');
+    writeFileSync(join(ws, 'skills', 'book-mirror', 'routing-eval.jsonl'), '{}\n');
+
+    // Now scaffold (gbrain bundle has the paired source declared); the
+    // existing skill files are preserved, the missing paired source lands.
+    const result = runScaffold({
+      gbrainRoot,
+      targetWorkspace: ws,
+      skillSlug: 'book-mirror',
+    });
+
+    expect(existsSync(join(ws, 'src', 'commands', 'book-mirror.ts'))).toBe(true);
+    expect(readFileSync(join(ws, 'skills', 'book-mirror', 'SKILL.md'), 'utf-8')).toBe(
+      '# pre-existing skill content\n',
+    );
+    expect(result.summary.pairedSourcesWritten).toBe(1);
+  });
+});
+
+describe('runScaffold — dry-run', () => {
+  it('reports outcomes without writing anything', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    const result = runScaffold({
+      gbrainRoot,
+      targetWorkspace: ws,
+      skillSlug: 'book-mirror',
+      dryRun: true,
+    });
+
+    expect(result.dryRun).toBe(true);
+    expect(result.summary.wroteNew).toBeGreaterThan(0);
+    expect(existsSync(join(ws, 'skills'))).toBe(false);
+  });
+});
+
+describe('runScaffold — error paths', () => {
+  it('unknown skill slug → ScaffoldError(unknown_skill)', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    try {
+      runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'does-not-exist' });
+      throw new Error('expected throw');
+    } catch (err) {
+      expect(err).toBeInstanceOf(ScaffoldError);
+      expect((err as ScaffoldError).code).toBe('unknown_skill');
+    }
+  });
+});
+
+describe('runScaffold — IRON-RULE regressions (R1, R2)', () => {
+  it('R1: never writes managed-block markers to RESOLVER.md/AGENTS.md', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    // Pre-create a RESOLVER.md so we can check it survives untouched.
+    writeFileSync(join(ws, 'RESOLVER.md'), '# my routing\n');
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+
+    const resolver = readFileSync(join(ws, 'RESOLVER.md'), 'utf-8');
+    expect(resolver).toBe('# my routing\n');
+    expect(resolver).not.toContain('gbrain:skillpack:begin');
+    expect(resolver).not.toContain('gbrain:skillpack:end');
+    expect(resolver).not.toContain('gbrain:skillpack:manifest');
+  });
+
+  it('R2: never writes a .gbrain-skillpack.lock file', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+
+    expect(existsSync(join(ws, '.gbrain-skillpack.lock'))).toBe(false);
+    // Lock should also not exist anywhere in the workspace tree.
+    expect(readdirSync(ws)).not.toContain('.gbrain-skillpack.lock');
+  });
+
+  it('R2: never writes a cumulative-slugs receipt anywhere in workspace', () => {
+    const { gbrainRoot } = scratchGbrain();
+    const ws = scratchWorkspace();
+
+    writeFileSync(join(ws, 'AGENTS.md'), 'existing agents content\n');
+
+    runScaffold({ gbrainRoot, targetWorkspace: ws, skillSlug: 'book-mirror' });
+
+    expect(readFileSync(join(ws, 'AGENTS.md'), 'utf-8')).not.toContain('cumulative-slugs');
+  });
+});