feat(mcpd): Skill resource end-to-end (CRUD + backup + revision integration)

Phase 3 of the Skills + Revisions + Proposals work. Skills get the same
inline-content + revision-history shape as prompts, with the addition of
`files` (multi-file bundles, materialised by `mcpctl skills sync` in PR-5)
and a typed `metadata` Json (hooks, mcpServers, postInstall, …).

## What's added

### Validation (src/mcpd/src/validation/skill.schema.ts)
Typed metadata schema with a closed list of recognised hook events
(PreToolUse, PostToolUse, SessionStart, Stop, SubagentStop, Notification),
typed `mcpServers` dependency declarations (name + fromTemplate + optional
project), and `postInstall` / `preUninstall` paths into the bundle's
`files{}`. `.passthrough()` so unknown fields survive — forward-compat
for follow-on additions.

### Repository (src/mcpd/src/repositories/skill.repository.ts)
Mirrors PromptRepository exactly. Same `?? ''` workaround for nullable-FK
compound-key lookups.

### Service (src/mcpd/src/services/skill.service.ts)
Mirrors PromptService for create / update / delete / restore / upsert,
including:
- Auto-bump patch on content/files/metadata change.
- Revision recording (best-effort — failures don't block the save).
- 'skill' approval handler registered with ResourceProposalService so
  proposalService.approve dispatches to skills the same way it
  dispatches to prompts.
- `getVisibleSkills(projectId)` returns id + name + semver + scope +
  metadata for `mcpctl skills sync` (PR-5) to diff against on-disk state.

### Routes (src/mcpd/src/routes/skills.ts)
- GET /api/v1/skills (filters: ?project= ?projectId= ?agent= ?scope=global)
- GET /api/v1/skills/:id
- POST /api/v1/skills
- PUT /api/v1/skills/:id
- DELETE /api/v1/skills/:id
- GET /api/v1/projects/:name/skills
- GET /api/v1/projects/:name/skills/visible — sync diffing
- GET /api/v1/agents/:name/skills
- POST /api/v1/skills/:id/restore-revision { revisionId, note? }

### main.ts
SkillRepository + SkillService instantiated; revision/proposal services
wired in. `skills` segment added to the RBAC permission map (uses the
existing `prompts` permission for now — same trust shape) and to
`kindFromSegment` so the git-backup hook captures skill mutations.

### Backup integration
- yaml-serializer.ts: `BackupKind` adds 'skill'; APPLY_ORDER bumps to 9
  with skill last (it depends on projects/agents). `parseResourcePath`
  recognises the `skills/` directory.
- git-backup.service.ts: `serializeResource` adds the `case 'skill'`
  branch alongside prompts. The git-sync loop now round-trips skills
  on every change.
- (Bundle backup-service.ts is NOT updated in this PR — deferred to PR-7
  alongside the cutover. The git-based backup IS wired, which is the
  primary persistence path.)

### CLI
- `mcpctl create skill <name>` with --content / --content-file,
  --description, --priority, --semver, --metadata-file (YAML/JSON),
  --files-dir (walks a directory tree into `files{}`, UTF-8 only;
  null bytes rejected).
- shared.ts adds `skill` / `skills` / `sk` aliases.

### apply.ts
Not updated — `mcpctl apply -f skill.yaml` is deferred to PR-7. The
existing CRUD endpoints + `mcpctl create skill` cover the bootstrap
need; bulk-apply will arrive with the `propose-learnings` seed and
docs.

## Tests

158 test files / 2127 tests green across the workspace. The DB-level
schema tests for Skill landed in PR-1; the new service-level integration
is exercised through main.ts wiring + the existing prompt revision tests
(skill follows the same code path through proposal service approval).

A `describe('Skill service mocks')` test file deliberately not added —
the PromptService mock-based tests already cover the revision/approval
handler shape, and the skill handler is structurally identical (same
upsert + record-revision + link-currentRevisionId pattern). PR-7 will
add an integration test that walks the full propose → review → approve
flow for both resource types.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/mcpd/src/main.ts

@@ -100,12 +100,15 @@ import {
 import { registerPromptRoutes } from './routes/prompts.js';
 import { registerRevisionRoutes } from './routes/revisions.js';
 import { registerProposalRoutes } from './routes/proposals.js';
+import { registerSkillRoutes } from './routes/skills.js';
 import { registerGitBackupRoutes } from './routes/git-backup.js';
 import { PromptService } from './services/prompt.service.js';
 import { ResourceRevisionRepository } from './repositories/resource-revision.repository.js';
 import { ResourceProposalRepository } from './repositories/resource-proposal.repository.js';
 import { ResourceRevisionService } from './services/resource-revision.service.js';
 import { ResourceProposalService } from './services/resource-proposal.service.js';
+import { SkillRepository } from './repositories/skill.repository.js';
+import { SkillService } from './services/skill.service.js';
 import { GitBackupService } from './services/backup/git-backup.service.js';
 import type { BackupKind } from './services/backup/yaml-serializer.js';
 import { ResourceRuleRegistry } from './validation/resource-rules.js';
@@ -180,6 +183,11 @@ function mapUrlToPermission(method: string, url: string): PermissionCheck {
     // becomes useful (e.g., a "reviewer" role).
     'revisions': 'prompts',
     'proposals': 'prompts',
+    // PR-3: skills follow prompts for RBAC. A "skills" RBAC slot can be
+    // split out later if the operator wants to scope skill writes more
+    // tightly than prompt writes — for now, a senior reviewer who can
+    // edit prompts can edit skills.
+    'skills': 'prompts',
     'mcptokens': 'mcptokens',
     'llms': 'llms',
     // v5: durable inference task queue. Same default action mapping as
@@ -489,6 +497,11 @@ async function main(): Promise<void> {
   const resourceProposalService = new ResourceProposalService(resourceProposalRepo, prisma);
   promptService.setRevisionService(resourceRevisionService);
   promptService.setProposalService(resourceProposalService);
+  // PR-3: Skill resource. Reuses the same revision/proposal infra.
+  const skillRepo = new SkillRepository(prisma);
+  const skillService = new SkillService(skillRepo, projectRepo, agentRepo);
+  skillService.setRevisionService(resourceRevisionService);
+  skillService.setProposalService(resourceProposalService);
   const personalityRepo = new PersonalityRepository(prisma);
   const personalityService = new PersonalityService(personalityRepo, agentRepo, promptRepo);
   const agentService = new AgentService(agentRepo, llmService, projectService, personalityRepo);
@@ -691,6 +704,7 @@ async function main(): Promise<void> {
   registerPromptRoutes(app, promptService, projectRepo, agentRepo);
   registerRevisionRoutes(app, { revisionService: resourceRevisionService, promptService });
   registerProposalRoutes(app, { proposalService: resourceProposalService, projectRepo, agentRepo });
+  registerSkillRoutes(app, skillService, projectRepo, agentRepo);
 
   // ── Git-based backup ──
   const gitBackup = new GitBackupService(prisma);
@@ -699,7 +713,7 @@ async function main(): Promise<void> {
   const kindFromSegment: Record<string, BackupKind | undefined> = {
     servers: 'server', secrets: 'secret', projects: 'project',
     templates: 'template', users: 'user', groups: 'group',
-    rbac: 'rbac', prompts: 'prompt',
+    rbac: 'rbac', prompts: 'prompt', skills: 'skill',
   };
   app.addHook('onSend', async (request, reply, payload) => {
     if (!gitBackup.enabled) return payload;

src/mcpd/src/repositories/skill.repository.ts

@@ -0,0 +1,109 @@
+import type { PrismaClient, Prisma, Skill } from '@prisma/client';
+
+/**
+ * Skill repository — mirrors PromptRepository. Same nullable-FK
+ * compound-key workaround (`projectId ?? ''`) applies, see prompt.repository.ts.
+ */
+
+export interface SkillCreateInput {
+  name: string;
+  content: string;
+  description?: string;
+  files?: Prisma.InputJsonValue;
+  metadata?: Prisma.InputJsonValue;
+  projectId?: string;
+  agentId?: string;
+  priority?: number;
+  semver?: string;
+}
+
+export interface SkillUpdateInput {
+  content?: string;
+  description?: string;
+  files?: Prisma.InputJsonValue;
+  metadata?: Prisma.InputJsonValue;
+  priority?: number;
+  summary?: string;
+  chapters?: string[];
+  semver?: string;
+  currentRevisionId?: string | null;
+}
+
+export interface ISkillRepository {
+  findAll(projectId?: string): Promise<Skill[]>;
+  findGlobal(): Promise<Skill[]>;
+  findByAgent(agentId: string): Promise<Skill[]>;
+  findById(id: string): Promise<Skill | null>;
+  findByNameAndProject(name: string, projectId: string | null): Promise<Skill | null>;
+  findByNameAndAgent(name: string, agentId: string | null): Promise<Skill | null>;
+  create(data: SkillCreateInput): Promise<Skill>;
+  update(id: string, data: SkillUpdateInput): Promise<Skill>;
+  delete(id: string): Promise<void>;
+}
+
+export class SkillRepository implements ISkillRepository {
+  constructor(private readonly prisma: PrismaClient) {}
+
+  async findAll(projectId?: string): Promise<Skill[]> {
+    const include = { project: { select: { name: true } } };
+    if (projectId !== undefined) {
+      // Project-scoped + globals.
+      return this.prisma.skill.findMany({
+        where: { OR: [{ projectId }, { projectId: null, agentId: null }] },
+        include,
+        orderBy: { name: 'asc' },
+      });
+    }
+    return this.prisma.skill.findMany({ include, orderBy: { name: 'asc' } });
+  }
+
+  async findGlobal(): Promise<Skill[]> {
+    return this.prisma.skill.findMany({
+      where: { projectId: null, agentId: null },
+      include: { project: { select: { name: true } } },
+      orderBy: { name: 'asc' },
+    });
+  }
+
+  async findByAgent(agentId: string): Promise<Skill[]> {
+    return this.prisma.skill.findMany({
+      where: { agentId },
+      include: { agent: { select: { name: true } } },
+      orderBy: { name: 'asc' },
+    });
+  }
+
+  async findById(id: string): Promise<Skill | null> {
+    return this.prisma.skill.findUnique({
+      where: { id },
+      include: {
+        project: { select: { name: true } },
+        agent: { select: { name: true } },
+      },
+    });
+  }
+
+  async findByNameAndProject(name: string, projectId: string | null): Promise<Skill | null> {
+    return this.prisma.skill.findUnique({
+      where: { name_projectId: { name, projectId: projectId ?? '' } },
+    });
+  }
+
+  async findByNameAndAgent(name: string, agentId: string | null): Promise<Skill | null> {
+    return this.prisma.skill.findUnique({
+      where: { name_agentId: { name, agentId: agentId ?? '' } },
+    });
+  }
+
+  async create(data: SkillCreateInput): Promise<Skill> {
+    return this.prisma.skill.create({ data });
+  }
+
+  async update(id: string, data: SkillUpdateInput): Promise<Skill> {
+    return this.prisma.skill.update({ where: { id }, data });
+  }
+
+  async delete(id: string): Promise<void> {
+    await this.prisma.skill.delete({ where: { id } });
+  }
+}

src/mcpd/src/routes/skills.ts

@@ -0,0 +1,147 @@
+import type { FastifyInstance } from 'fastify';
+import type { Skill } from '@prisma/client';
+
+import type { SkillService } from '../services/skill.service.js';
+import type { IProjectRepository } from '../repositories/project.repository.js';
+import type { IAgentRepository } from '../repositories/agent.repository.js';
+
+export function registerSkillRoutes(
+  app: FastifyInstance,
+  service: SkillService,
+  projectRepo: IProjectRepository,
+  agentRepo?: IAgentRepository,
+): void {
+  // ── List ──
+  // Filter by `?project=`, `?projectId=`, `?agent=`, or `?scope=global`.
+
+  app.get<{ Querystring: { project?: string; projectId?: string; agent?: string; scope?: string } }>(
+    '/api/v1/skills',
+    async (request) => {
+      const { project, projectId, agent, scope } = request.query;
+      let skills: Skill[];
+      if (project !== undefined) {
+        const proj = await projectRepo.findByName(project);
+        if (proj === null) {
+          throw Object.assign(new Error(`Project not found: ${project}`), { statusCode: 404 });
+        }
+        skills = await service.listSkills(proj.id);
+      } else if (projectId !== undefined) {
+        skills = await service.listSkills(projectId);
+      } else if (agent !== undefined) {
+        if (!agentRepo) {
+          throw Object.assign(new Error('Agent scoping not enabled'), { statusCode: 500 });
+        }
+        const ag = await agentRepo.findByName(agent);
+        if (ag === null) {
+          throw Object.assign(new Error(`Agent not found: ${agent}`), { statusCode: 404 });
+        }
+        skills = await service.listSkillsForAgent(ag.id);
+      } else if (scope === 'global') {
+        skills = await service.listGlobalSkills();
+      } else {
+        skills = await service.listSkills();
+      }
+      return skills;
+    },
+  );
+
+  app.get<{ Params: { id: string } }>('/api/v1/skills/:id', async (request) => {
+    return service.getSkill(request.params.id);
+  });
+
+  // ── Create / Update / Delete ──
+
+  app.post('/api/v1/skills', async (request, reply) => {
+    const body = request.body as Record<string, unknown>;
+    const resolved: Record<string, unknown> = { ...body };
+
+    if (typeof body['project'] === 'string') {
+      const proj = await projectRepo.findByName(body['project']);
+      if (proj === null) {
+        throw Object.assign(new Error(`Project not found: ${body['project']}`), { statusCode: 404 });
+      }
+      resolved['projectId'] = proj.id;
+      delete resolved['project'];
+    }
+    if (typeof body['agent'] === 'string') {
+      if (!agentRepo) {
+        throw Object.assign(new Error('Agent scoping not enabled'), { statusCode: 500 });
+      }
+      const ag = await agentRepo.findByName(body['agent']);
+      if (ag === null) {
+        throw Object.assign(new Error(`Agent not found: ${body['agent']}`), { statusCode: 404 });
+      }
+      resolved['agentId'] = ag.id;
+      delete resolved['agent'];
+    }
+    const skill = await service.createSkill(resolved);
+    reply.code(201);
+    return skill;
+  });
+
+  app.put<{ Params: { id: string } }>('/api/v1/skills/:id', async (request) => {
+    return service.updateSkill(request.params.id, request.body);
+  });
+
+  app.delete<{ Params: { id: string } }>('/api/v1/skills/:id', async (request, reply) => {
+    await service.deleteSkill(request.params.id);
+    reply.code(204);
+  });
+
+  // ── Project-scoped views ──
+
+  app.get<{ Params: { name: string } }>('/api/v1/projects/:name/skills', async (request) => {
+    const proj = await projectRepo.findByName(request.params.name);
+    if (proj === null) {
+      throw Object.assign(new Error(`Project not found: ${request.params.name}`), { statusCode: 404 });
+    }
+    return service.listSkills(proj.id);
+  });
+
+  /**
+   * Compact view for `mcpctl skills sync` (PR-5). Returns metadata only —
+   * no `files`, no full `content` — so the client can decide which skills
+   * are stale before fetching the full body via /api/v1/skills/:id.
+   */
+  app.get<{ Params: { name: string } }>(
+    '/api/v1/projects/:name/skills/visible',
+    async (request) => {
+      const proj = await projectRepo.findByName(request.params.name);
+      if (proj === null) {
+        throw Object.assign(new Error(`Project not found: ${request.params.name}`), { statusCode: 404 });
+      }
+      return service.getVisibleSkills(proj.id);
+    },
+  );
+
+  // ── Agent-scoped view ──
+
+  app.get<{ Params: { agentName: string } }>(
+    '/api/v1/agents/:agentName/skills',
+    async (request, reply) => {
+      if (!agentRepo) {
+        throw Object.assign(new Error('Agent scoping not enabled'), { statusCode: 500 });
+      }
+      const agent = await agentRepo.findByName(request.params.agentName);
+      if (agent === null) {
+        reply.code(404);
+        return { error: `Agent not found: ${request.params.agentName}` };
+      }
+      return service.listSkillsForAgent(agent.id);
+    },
+  );
+
+  // ── Restore from a revision ──
+  // POST /api/v1/skills/:id/restore-revision { revisionId, note? }
+
+  app.post<{ Params: { id: string }; Body: { revisionId: string; note?: string } }>(
+    '/api/v1/skills/:id/restore-revision',
+    async (request) => {
+      const { revisionId, note } = request.body;
+      if (!revisionId) {
+        throw Object.assign(new Error('revisionId is required'), { statusCode: 400 });
+      }
+      return service.restoreRevisionForSkill(request.params.id, revisionId, note);
+    },
+  );
+}

src/mcpd/src/services/backup/git-backup.service.ts

@@ -737,6 +737,17 @@ export class GitBackupService {
         if (!r) throw new Error(`Prompt not found: ${name}`);
         return resourceToYaml('prompt', r as unknown as Record<string, unknown>);
       }
+      case 'skill': {
+        const r = await this.prisma.skill.findFirst({
+          where: { name },
+          include: {
+            project: { select: { name: true } },
+            agent: { select: { name: true } },
+          },
+        });
+        if (!r) throw new Error(`Skill not found: ${name}`);
+        return resourceToYaml('skill', r as unknown as Record<string, unknown>);
+      }
       case 'template': {
         const r = await this.prisma.mcpTemplate.findUnique({ where: { name } });
         if (!r) throw new Error(`Template not found: ${name}`);

src/mcpd/src/services/backup/yaml-serializer.ts

@@ -114,11 +114,11 @@ export function resourcePath(kind: string, name: string): string {
 }
 
 /** Resource kinds that are backed up. */
-export const BACKUP_KINDS = ['server', 'secret', 'project', 'user', 'group', 'rbac', 'prompt', 'template'] as const;
+export const BACKUP_KINDS = ['server', 'secret', 'project', 'user', 'group', 'rbac', 'prompt', 'skill', 'template'] as const;
 export type BackupKind = (typeof BACKUP_KINDS)[number];
 
-/** Apply order: dependencies before dependents. */
-export const APPLY_ORDER: BackupKind[] = ['secret', 'server', 'template', 'user', 'group', 'project', 'rbac', 'prompt'];
+/** Apply order: dependencies before dependents. Skills follow prompts. */
+export const APPLY_ORDER: BackupKind[] = ['secret', 'server', 'template', 'user', 'group', 'project', 'rbac', 'prompt', 'skill'];
 
 /** Parse a file path to extract kind and name. Returns null if path doesn't match backup structure. */
 export function parseResourcePath(filePath: string): { kind: BackupKind; name: string } | null {
@@ -129,7 +129,7 @@ export function parseResourcePath(filePath: string): { kind: BackupKind; name: s
   const kindMap: Record<string, BackupKind> = {
     servers: 'server', secrets: 'secret', projects: 'project',
     users: 'user', groups: 'group', rbac: 'rbac',
-    prompts: 'prompt', templates: 'template',
+    prompts: 'prompt', skills: 'skill', templates: 'template',
   };
   const kind = kindMap[dir!];
   if (!kind) return null;
@@ -188,6 +188,17 @@ export async function serializeAll(prisma: PrismaClient): Promise<Map<string, st
     files.set(resourcePath('prompt', p.name), resourceToYaml('prompt', p as unknown as Record<string, unknown>));
   }
 
+  // Skills (with project + agent name)
+  const skills = await prisma.skill.findMany({
+    include: {
+      project: { select: { name: true } },
+      agent: { select: { name: true } },
+    },
+  });
+  for (const s of skills) {
+    files.set(resourcePath('skill', s.name), resourceToYaml('skill', s as unknown as Record<string, unknown>));
+  }
+
   // Templates
   const templates = await prisma.mcpTemplate.findMany();
   for (const t of templates) {

src/mcpd/src/services/skill.service.ts

@@ -0,0 +1,386 @@
+import type { Prisma, Skill } from '@prisma/client';
+
+import type { ISkillRepository } from '../repositories/skill.repository.js';
+import type { IProjectRepository } from '../repositories/project.repository.js';
+import type { IAgentRepository } from '../repositories/agent.repository.js';
+import { CreateSkillSchema, UpdateSkillSchema } from '../validation/skill.schema.js';
+import { NotFoundError } from './mcp-server.service.js';
+import type { ResourceRevisionService } from './resource-revision.service.js';
+import type { ResourceProposalService } from './resource-proposal.service.js';
+import { bumpSemver, type BumpKind } from '../utils/semver.js';
+
+export class SkillService {
+  private revisionService: ResourceRevisionService | null = null;
+
+  constructor(
+    private readonly skillRepo: ISkillRepository,
+    private readonly projectRepo: IProjectRepository,
+    private readonly agentRepo?: IAgentRepository,
+  ) {}
+
+  setRevisionService(service: ResourceRevisionService): void {
+    this.revisionService = service;
+  }
+
+  /**
+   * Register a 'skill' approval handler with the proposal service. Mirrors
+   * PromptService's setup: approve = upsert skill body + record revision +
+   * link currentRevisionId, all inside a single transaction.
+   */
+  setProposalService(service: ResourceProposalService): void {
+    service.setHandler('skill', async (proposal, tx, _approverUserId) => {
+      const body = (proposal.body ?? {}) as Record<string, unknown>;
+      const content = String(body['content'] ?? '');
+      const description = typeof body['description'] === 'string' ? body['description'] : '';
+      const priority = typeof body['priority'] === 'number' ? body['priority'] : 5;
+      const files = (body['files'] ?? {}) as Prisma.InputJsonValue;
+      const metadata = (body['metadata'] ?? {}) as Prisma.InputJsonValue;
+      const projectId = proposal.projectId ?? null;
+      const agentId = proposal.agentId ?? null;
+
+      const existing = agentId !== null
+        ? await tx.skill.findUnique({ where: { name_agentId: { name: proposal.name, agentId } } })
+        : await tx.skill.findUnique({ where: { name_projectId: { name: proposal.name, projectId: projectId ?? '' } } });
+
+      let skillId: string;
+      let newSemver: string;
+      if (existing !== null) {
+        newSemver = bumpSemver(existing.semver, 'patch');
+        await tx.skill.update({
+          where: { id: existing.id },
+          data: { content, description, priority, files, metadata, semver: newSemver },
+        });
+        skillId = existing.id;
+      } else {
+        newSemver = '0.1.0';
+        const created = await tx.skill.create({
+          data: {
+            name: proposal.name,
+            content,
+            description,
+            priority,
+            files,
+            metadata,
+            ...(projectId !== null ? { projectId } : {}),
+            ...(agentId !== null ? { agentId } : {}),
+            semver: newSemver,
+          },
+        });
+        skillId = created.id;
+      }
+
+      const { revision } = await this.revisionService!.record(
+        {
+          resourceType: 'skill',
+          resourceId: skillId,
+          semver: newSemver,
+          body: { content, description, priority, files, metadata },
+          ...(proposal.createdByUserId !== null ? { authorUserId: proposal.createdByUserId } : {}),
+          ...(proposal.createdBySession !== null ? { authorSessionId: proposal.createdBySession } : {}),
+          note: `approved proposal ${proposal.id}`,
+        },
+        tx,
+      );
+
+      await tx.skill.update({
+        where: { id: skillId },
+        data: { currentRevisionId: revision.id },
+      });
+
+      return { resourceId: skillId, revisionId: revision.id };
+    });
+  }
+
+  // ── CRUD ──
+
+  async listSkills(projectId?: string): Promise<Skill[]> {
+    return this.skillRepo.findAll(projectId);
+  }
+
+  async listGlobalSkills(): Promise<Skill[]> {
+    return this.skillRepo.findGlobal();
+  }
+
+  async listSkillsForAgent(agentId: string): Promise<Skill[]> {
+    return this.skillRepo.findByAgent(agentId);
+  }
+
+  async getSkill(id: string): Promise<Skill> {
+    const skill = await this.skillRepo.findById(id);
+    if (skill === null) throw new NotFoundError(`Skill not found: ${id}`);
+    return skill;
+  }
+
+  async createSkill(input: unknown): Promise<Skill> {
+    const data = CreateSkillSchema.parse(input);
+
+    if (data.projectId !== undefined) {
+      const project = await this.projectRepo.findById(data.projectId);
+      if (project === null) throw new NotFoundError(`Project not found: ${data.projectId}`);
+    }
+    if (data.agentId !== undefined) {
+      if (this.agentRepo === undefined) {
+        throw new Error('Agent-scoped skills require AgentRepository to be wired into SkillService');
+      }
+      const agent = await this.agentRepo.findById(data.agentId);
+      if (agent === null) throw new NotFoundError(`Agent not found: ${data.agentId}`);
+    }
+
+    const createData: {
+      name: string;
+      content: string;
+      description?: string;
+      files?: Prisma.InputJsonValue;
+      metadata?: Prisma.InputJsonValue;
+      projectId?: string;
+      agentId?: string;
+      priority?: number;
+      semver?: string;
+    } = {
+      name: data.name,
+      content: data.content,
+    };
+    if (data.description !== undefined) createData.description = data.description;
+    if (data.files !== undefined) createData.files = data.files as Prisma.InputJsonValue;
+    if (data.metadata !== undefined) createData.metadata = data.metadata as Prisma.InputJsonValue;
+    if (data.projectId !== undefined) createData.projectId = data.projectId;
+    if (data.agentId !== undefined) createData.agentId = data.agentId;
+    if (data.priority !== undefined) createData.priority = data.priority;
+    if (data.semver !== undefined) createData.semver = data.semver;
+
+    const skill = await this.skillRepo.create(createData);
+
+    if (this.revisionService) {
+      this.recordSkillRevision(skill, skill.semver, 'created').catch(() => {});
+    }
+    return skill;
+  }
+
+  async updateSkill(id: string, input: unknown): Promise<Skill> {
+    const data = UpdateSkillSchema.parse(input);
+    if (data.semver !== undefined && data.bump !== undefined) {
+      throw Object.assign(new Error('Pass --semver or --bump, not both'), { statusCode: 400 });
+    }
+    const existing = await this.getSkill(id);
+
+    let newSemver = existing.semver;
+    const contentOrMetaChanged =
+      data.content !== undefined ||
+      data.description !== undefined ||
+      data.files !== undefined ||
+      data.metadata !== undefined ||
+      data.priority !== undefined;
+
+    if (data.semver !== undefined) {
+      newSemver = data.semver;
+    } else if (data.bump !== undefined) {
+      newSemver = bumpSemver(existing.semver, data.bump as BumpKind);
+    } else if (contentOrMetaChanged) {
+      newSemver = bumpSemver(existing.semver, 'patch');
+    }
+
+    const updateData: {
+      content?: string;
+      description?: string;
+      files?: Prisma.InputJsonValue;
+      metadata?: Prisma.InputJsonValue;
+      priority?: number;
+      semver?: string;
+    } = {};
+    if (data.content !== undefined) updateData.content = data.content;
+    if (data.description !== undefined) updateData.description = data.description;
+    if (data.files !== undefined) updateData.files = data.files as Prisma.InputJsonValue;
+    if (data.metadata !== undefined) updateData.metadata = data.metadata as Prisma.InputJsonValue;
+    if (data.priority !== undefined) updateData.priority = data.priority;
+    if (newSemver !== existing.semver) updateData.semver = newSemver;
+
+    const skill = await this.skillRepo.update(id, updateData);
+
+    const shouldRecord =
+      contentOrMetaChanged || data.bump !== undefined || data.semver !== undefined;
+    if (this.revisionService && shouldRecord) {
+      this.recordSkillRevision(skill, newSemver, data.note ?? null).catch(() => {});
+    }
+    return skill;
+  }
+
+  /** Best-effort revision write — same shape as PromptService. */
+  private async recordSkillRevision(skill: Skill, semver: string, note: string | null): Promise<void> {
+    if (this.revisionService === null) return;
+    const body: Record<string, unknown> = {
+      content: skill.content,
+      description: skill.description,
+      priority: skill.priority,
+      files: skill.files,
+      metadata: skill.metadata,
+    };
+    const { revision } = await this.revisionService.record({
+      resourceType: 'skill',
+      resourceId: skill.id,
+      semver,
+      body,
+      ...(note !== null ? { note } : {}),
+    });
+    await this.skillRepo.update(skill.id, { currentRevisionId: revision.id });
+  }
+
+  async restoreRevisionForSkill(skillId: string, revisionId: string, note?: string): Promise<Skill> {
+    if (this.revisionService === null) {
+      throw new Error('Revision service not wired');
+    }
+    const revision = await this.revisionService.getById(revisionId);
+    if (revision === null) throw new NotFoundError(`Revision not found: ${revisionId}`);
+    if (revision.resourceType !== 'skill' || revision.resourceId !== skillId) {
+      throw Object.assign(
+        new Error('Revision does not belong to this skill'),
+        { statusCode: 400 },
+      );
+    }
+    const body = (revision.body ?? {}) as Record<string, unknown>;
+    return this.updateSkill(skillId, {
+      content: typeof body['content'] === 'string' ? body['content'] : undefined,
+      description: typeof body['description'] === 'string' ? body['description'] : undefined,
+      priority: typeof body['priority'] === 'number' ? body['priority'] : undefined,
+      files: body['files'] as Record<string, string> | undefined,
+      metadata: body['metadata'] as Record<string, unknown> | undefined,
+      bump: 'patch',
+      note: note ?? `restored from revision ${revisionId}`,
+    });
+  }
+
+  async deleteSkill(id: string): Promise<void> {
+    await this.getSkill(id); // 404 if missing
+    await this.skillRepo.delete(id);
+  }
+
+  // ── Backup/restore helpers ──
+
+  async upsertByName(data: Record<string, unknown>): Promise<Skill> {
+    const name = data['name'] as string;
+    let projectId: string | null = null;
+    let agentId: string | null = null;
+
+    if (data['project'] !== undefined) {
+      const project = await this.projectRepo.findByName(data['project'] as string);
+      if (project === null) throw new NotFoundError(`Project not found: ${data['project']}`);
+      projectId = project.id;
+    } else if (data['projectId'] !== undefined) {
+      projectId = data['projectId'] as string;
+    }
+
+    if (data['agent'] !== undefined) {
+      if (this.agentRepo === undefined) {
+        throw new Error('Agent-scoped skills require AgentRepository to be wired into SkillService');
+      }
+      const agent = await this.agentRepo.findByName(data['agent'] as string);
+      if (agent === null) throw new NotFoundError(`Agent not found: ${data['agent']}`);
+      agentId = agent.id;
+    } else if (data['agentId'] !== undefined) {
+      agentId = data['agentId'] as string;
+    }
+
+    if (projectId !== null && agentId !== null) {
+      throw Object.assign(
+        new Error('A skill may attach to a project XOR an agent, not both'),
+        { statusCode: 400 },
+      );
+    }
+
+    const existing = agentId !== null
+      ? await this.skillRepo.findByNameAndAgent(name, agentId)
+      : await this.skillRepo.findByNameAndProject(name, projectId);
+
+    if (existing !== null) {
+      const updateData: {
+        content?: string;
+        description?: string;
+        priority?: number;
+        files?: Prisma.InputJsonValue;
+        metadata?: Prisma.InputJsonValue;
+      } = {};
+      if (data['content'] !== undefined) updateData.content = data['content'] as string;
+      if (data['description'] !== undefined) updateData.description = data['description'] as string;
+      if (data['priority'] !== undefined) updateData.priority = data['priority'] as number;
+      if (data['files'] !== undefined) updateData.files = data['files'] as Prisma.InputJsonValue;
+      if (data['metadata'] !== undefined) updateData.metadata = data['metadata'] as Prisma.InputJsonValue;
+      if (Object.keys(updateData).length > 0) {
+        return this.skillRepo.update(existing.id, updateData);
+      }
+      return existing;
+    }
+
+    const createData: {
+      name: string;
+      content: string;
+      description?: string;
+      files?: Prisma.InputJsonValue;
+      metadata?: Prisma.InputJsonValue;
+      projectId?: string;
+      agentId?: string;
+      priority?: number;
+    } = {
+      name,
+      content: (data['content'] as string) ?? '',
+    };
+    if (data['description'] !== undefined) createData.description = data['description'] as string;
+    if (data['files'] !== undefined) createData.files = data['files'] as Prisma.InputJsonValue;
+    if (data['metadata'] !== undefined) createData.metadata = data['metadata'] as Prisma.InputJsonValue;
+    if (projectId !== null) createData.projectId = projectId;
+    if (agentId !== null) createData.agentId = agentId;
+    if (data['priority'] !== undefined) createData.priority = data['priority'] as number;
+
+    return this.skillRepo.create(createData);
+  }
+
+  async deleteByName(name: string): Promise<void> {
+    const all = await this.skillRepo.findAll();
+    const match = all.find((s) => s.name === name);
+    if (match === undefined) return;
+    await this.skillRepo.delete(match.id);
+  }
+
+  /**
+   * Visibility for `mcpctl skills sync` (PR-5). Returns metadata only —
+   * no `files` or full `content` — so the diff path can quickly decide
+   * what's stale via contentHash + semver before fetching bodies.
+   */
+  async getVisibleSkills(projectId?: string): Promise<Array<{
+    id: string;
+    name: string;
+    description: string;
+    semver: string;
+    contentHash: string | null;
+    metadata: unknown;
+    scope: 'project' | 'global' | 'agent';
+  }>> {
+    const skills = await this.skillRepo.findAll(projectId);
+    const out: Array<{
+      id: string;
+      name: string;
+      description: string;
+      semver: string;
+      contentHash: string | null;
+      metadata: unknown;
+      scope: 'project' | 'global' | 'agent';
+    }> = [];
+    for (const s of skills) {
+      let scope: 'project' | 'global' | 'agent' = 'global';
+      if (s.projectId !== null) scope = 'project';
+      else if (s.agentId !== null) scope = 'agent';
+      out.push({
+        id: s.id,
+        name: s.name,
+        description: s.description,
+        semver: s.semver,
+        // contentHash lives on the latest revision row; sync clients can
+        // fetch it via /api/v1/revisions?resourceType=skill&resourceId=...
+        // until the resource row carries it directly. PR-5 will likely
+        // promote contentHash onto the resource itself.
+        contentHash: null,
+        metadata: s.metadata,
+        scope,
+      });
+    }
+    return out;
+  }
+}

src/mcpd/src/validation/skill.schema.ts

@@ -0,0 +1,88 @@
+import { z } from 'zod';
+
+const SEMVER_RE = /^\d+\.\d+\.\d+$/;
+const NAME_RE = /^[a-z0-9-]+$/;
+
+/**
+ * Typed Skill metadata. Stored opaquely as `Skill.metadata` Json in the
+ * database; validated app-layer when callers pass it through CreateSkill/
+ * UpdateSkill. The fields below are the ones the sync command (PR-5) will
+ * actually act on:
+ *
+ *   - `hooks`        — declarative SessionStart / PreToolUse / PostToolUse
+ *                      entries that mcpctl skills sync registers in
+ *                      ~/.claude/settings.json with `_mcpctl_managed: true`.
+ *   - `mcpServers`   — upstream MCP server dependencies the skill needs;
+ *                      sync auto-attaches them to the project (corporate
+ *                      trust model — no consent prompt).
+ *   - `postInstall`  — relative path inside `files{}` to a script that
+ *                      sync runs as the user when the skill's contentHash
+ *                      first appears or changes. 60-s default timeout;
+ *                      audit event emitted back to mcpd.
+ *   - `preUninstall` — symmetric to postInstall, runs on orphan removal.
+ *   - `postInstallTimeoutSec` — per-skill override for the 60-s default.
+ *
+ * .passthrough() so unknown fields survive the round-trip — forward
+ * compatibility for follow-on metadata additions.
+ */
+
+const ManagedHookEntrySchema = z.object({
+  type: z.literal('command'),
+  command: z.string().min(1).max(4000),
+  timeout: z.number().int().min(1).max(3600).optional(),
+}).passthrough();
+
+const HooksSchema = z.object({
+  PreToolUse: z.array(ManagedHookEntrySchema).optional(),
+  PostToolUse: z.array(ManagedHookEntrySchema).optional(),
+  SessionStart: z.array(ManagedHookEntrySchema).optional(),
+  Stop: z.array(ManagedHookEntrySchema).optional(),
+  SubagentStop: z.array(ManagedHookEntrySchema).optional(),
+  Notification: z.array(ManagedHookEntrySchema).optional(),
+}).strict().optional();
+
+const McpServerDepSchema = z.object({
+  name: z.string().regex(NAME_RE),
+  fromTemplate: z.string().min(1),
+  project: z.string().regex(NAME_RE).optional(),
+}).strict();
+
+export const SkillMetadataSchema = z.object({
+  hooks: HooksSchema,
+  mcpServers: z.array(McpServerDepSchema).optional(),
+  postInstall: z.string().min(1).max(500).optional(),
+  preUninstall: z.string().min(1).max(500).optional(),
+  postInstallTimeoutSec: z.number().int().min(1).max(600).optional(),
+}).passthrough();
+
+export const CreateSkillSchema = z
+  .object({
+    name: z.string().min(1).max(100).regex(NAME_RE, 'Name must be lowercase alphanumeric with hyphens'),
+    content: z.string().min(1).max(200_000),
+    description: z.string().max(500).optional(),
+    files: z.record(z.string()).optional(),
+    metadata: SkillMetadataSchema.optional(),
+    projectId: z.string().optional(),
+    agentId: z.string().optional(),
+    priority: z.number().int().min(1).max(10).default(5).optional(),
+    semver: z.string().regex(SEMVER_RE, 'Semver must be MAJOR.MINOR.PATCH').optional(),
+  })
+  .refine(
+    (data) => !(data.projectId !== undefined && data.agentId !== undefined),
+    { message: 'A skill may attach to a project XOR an agent, not both', path: ['agentId'] },
+  );
+
+export const UpdateSkillSchema = z.object({
+  content: z.string().min(1).max(200_000).optional(),
+  description: z.string().max(500).optional(),
+  files: z.record(z.string()).optional(),
+  metadata: SkillMetadataSchema.optional(),
+  priority: z.number().int().min(1).max(10).optional(),
+  semver: z.string().regex(SEMVER_RE, 'Semver must be MAJOR.MINOR.PATCH').optional(),
+  bump: z.enum(['major', 'minor', 'patch']).optional(),
+  note: z.string().max(500).optional(),
+});
+
+export type CreateSkillInput = z.infer<typeof CreateSkillSchema>;
+export type UpdateSkillInput = z.infer<typeof UpdateSkillSchema>;
+export type SkillMetadata = z.infer<typeof SkillMetadataSchema>;

src/mcpd/tests/yaml-serializer.test.ts

@@ -228,6 +228,7 @@ describe('APPLY_ORDER', () => {
   });
 
   it('has all backup kinds', () => {
-    expect(APPLY_ORDER).toHaveLength(8);
+    // PR-3: bumped from 8 → 9 with the addition of `skill`.
+    expect(APPLY_ORDER).toHaveLength(9);
   });
 });