feat: add rhdh-coding skill for Backstage/RHDH plugin development

[rohitkrai03]

Why

RHDH is moving toward an agentic SDLC with fullsend — agents triage issues, implement features, and review code autonomously. The coding agent needs Backstage/RHDH patterns that aren't in training data (BUI is new, NFS is evolving, dynamic plugin conventions are tribal knowledge). No Backstage coding skills exist in the open-source ecosystem — the official backstage.io skills cover migrations and instrumentation, not day-to-day feature development.

This skill fills that gap. It's the daily-driver skill for agents working on RHDH plugins — installed into .fullsend/customized/skills/ alongside rhdh-workspace and available to the code agent during implementation. It also helps human developers using Claude Code, Cursor, or any skills-compatible agent.

What it covers

• BUI-first styling — component mapping, CSS variables, Remix icons (too new for training data)
• NFS Blueprints — PageBlueprint, EntityCardBlueprint, alpha exports, NFS-at-root pattern
• RHDH dynamic plugins — default export gotcha, scalprum naming, class name generator
• Dev app setup — both plugin dev mode and full Backstage app with sidebar nav
• Backstage-specific testing — TestApiProvider, renderInTestApp, entity mocking, MSW
• Plugin type decisions — page vs card vs entity tab vs backend module
• Frontend spec guidance — what to include in PRDs/OpenSpec proposals for frontend features
• Version compatibility — RHDH → Backstage version matrix awareness

How it fits into fullsend

# .fullsend/customized/harness/code.yaml
skills:
  - skills/code-implementation    # base fullsend
  - skills/rhdh-workspace         # monorepo navigation
  - skills/rhdh-coding            # Backstage/RHDH patterns (this skill)

Complements ecosystem skills (ui-ux-pro-max, frontend-design, webapp-testing) for generic UI quality, and official backstage.io skills for migration workflows.

Summary

• 9 files, ~1,200 lines
• References verified against real plugin code in rhdh-plugins and community-plugins
• Tested against a real NFS plugin implementation (boost workspace) — feedback incorporated
• Detection script verified against orchestrator and bulk-import plugins

Files

File	Lines	Purpose
SKILL.md	176	Core skill — principles, BUI-first, NFS, RHDH gotchas, sibling + official skill references
references/bui.md	149	BUI component mapping, CSS variables, Remix icons
references/dev-app.md	212	Plugin dev mode + full Backstage app setup
references/nfs.md	155	NFS Blueprints, package exports, compatWrapper
references/frontend-specs.md	86	Frontend spec guidance for PRDs/OpenSpec
references/plugin-types.md	79	Plugin type decision guide
references/rhdh.md	141	RHDH-specific patterns
references/testing.md	122	Backstage test patterns
scripts/detect-rhdh-context.py	163	Plugin context detection

Test plan

• Detection script tested against orchestrator and bulk-import plugins
• Skill tested in Cursor against real NFS plugin implementation (boost workspace)
• Real usage feedback incorporated (dev-app gaps, NavItemBlueprint removal, PageBlueprint title, translation auto-discovery, NFS-at-root pattern)
• Install via npx skills add and verify skill triggers correctly

🤖 Generated with Claude Code