feat(skill-hub): org-wide skill hub for agent procedural memory

[ZaltaClaw]

What changed

Adds a complete Skill Hub module — an org-wide library of reusable procedural memory skills that can be assigned to any agent at runtime.

New files

Path	Purpose
src/types/agent.ts	Added Skill, SkillVisibility, CreateSkillRequest, UpdateSkillRequest types
src/lib/skill-store.ts	SkillStore adapter — file-based CRUD backed by data/skills/*.md
src/app/skill-hub/page.tsx	Skill Hub page (browse grid, search, CRUD, modals)
src/app/api/skill-hub/route.ts	GET /api/skill-hub (list + filter), POST /api/skill-hub (create)
src/app/api/skill-hub/[slug]/route.ts	GET, PUT, DELETE /api/skill-hub/:slug
src/components/skill-hub/skill-card.tsx	Browse grid card (pinned indicator, tags, visibility, assign button)
src/components/skill-hub/skill-detail.tsx	Full detail modal (metadata, tags, env vars, content preview)
src/components/skill-hub/skill-editor.tsx	Create/edit modal with markdown editor + preview toggle
src/components/skill-hub/skill-filters.tsx	Visibility tab bar + tag chip filters
src/components/skill-hub/assign-skill-modal.tsx	Agent picker — appends skill content to agent system prompt
data/skills/azure-deployment-style.md	Seed: Azure infra naming, Bicep, managed identity, zero-trust
data/skills/code-review-checklist.md	Seed: Security, perf, observability, quality checklist
data/skills/incident-response.md	Seed: P0–P3 severity, response steps, communication template
data/skills/prompt-engineering-guide.md	Seed: System prompt structure, principles, anti-patterns

Modified files

• src/components/layout/sidebar.tsx — Added Skill Hub nav entry between Tools and Knowledge in the Build group
• README.md — Added Skill Hub subsection under Features
• .gitignore — Unignored data/skills/** so seed markdown files are tracked

Design decisions

File-based JSON/Markdown storage

Skills are stored as data/skills/<slug>.md files with YAML-like frontmatter + markdown body. This was chosen for the initial implementation because:

• Zero infrastructure dependency — works immediately with no database setup
• Skills are human-readable and diff-friendly in version control
• Easy to seed via PRs (just add a .md file)
• SkillStore exposes a clean interface (list, get, create, update, delete) that maps 1:1 to what a Cosmos/Postgres adapter would need

Skill → Agent assignment

The "Assign to Agent" flow appends the skill's markdown body to the selected agent's instructions field via PUT /api/agents/local/:id. This is the simplest runtime injection mechanism that works without changes to the inference path. A future iteration could use a structured skills array on the agent object and inject at request time.

Type naming

The Skill Hub types use Skill (not HubSkill) in agent.ts. The existing src/types/skill.ts file was checked and uses a different interface for a different domain — no collision.

Follow-up plan

• Cosmos/Postgres adapter: Swap SkillStore implementation when a DB is available — the interface is identical, no callsite changes needed
• Skill versioning: Track version history in the frontmatter, add a changelog view in SkillDetail
• Agent skills section: Add a "Skills" tab to the agent detail page showing attached skills with chip UI
• Import/export: Bulk export skills as a zip of .md files, import from external repos
• Skill analytics: Track which skills are most-assigned and which agents use them

Screenshots

Screenshots directory: docs/screenshots/

Skill Hub grid, detail modal, editor, and assign flow follow the existing dark-theme design system (cyan/purple accents, CSS variable tokens, consistent card/modal patterns from Marketplace and Tools pages).

Acceptance checklist

• npm run lint — 0 new errors (58 pre-existing errors in unrelated files unchanged)
• npm run build — clean build, /skill-hub appears as static route, /api/skill-hub and /api/skill-hub/[slug] as dynamic routes
• Sidebar nav updated (Skill Hub between Tools and Knowledge)
• 4 seed skills committed under data/skills/
• README.md Skill Hub subsection added

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