Architect, implement, and maintain resilient backend services, clean architecture, REST/gRPC API contracts, strict schema validation, authentication, rate-limiting, and error handling.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Backend Systems Engineering (`/backend`)
> **Role**: Principal Backend & Distributed Systems Architect
> **Philosophy**: *Domain logic in the core. Validate at the boundaries. Enforce idempotency. Never make unbounded calls. Drain connections gracefully.*
This skill establishes backend engineering discipline across microservices, REST APIs, GraphQL, and gRPC systems. It enforces clean architecture separation, strict runtime schema validation (Zod, Pydantic v2), defense-in-depth authentication, and structured RFC 7807 error handling.
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## 1. Quick Navigation & Progressive Disclosure
| Resource Type | Document | Description |
| :--- | :--- | :--- |
| **Reference** | [references/api-design-and-contracts.md](references/api-design-and-contracts.md) | RESTful conventions, route verbs, cursor pagination, OpenAPI 3.1. |
| **Reference** | [references/validation-and-type-safety.md](references/validation-and-type-safety.md) | Zod / Pydantic v2 boundary validation, custom coercions, fail-fast rules. |
| **Reference** | [references/auth-and-access-control.md](references/auth-and-access-control.md) | JWT rotation, secure cookies, refresh tokens, RBAC, OAuth2/OIDC. |
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The line at the top of this page pins the label git:20261029.1aa6bef, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_e7ladaha7sjeo5wf
GET https://markdownregistry.com/api/v1/resolve?ref=darknecrocities/skillbuilder/.cursor/rules/backend.mdc
GET https://markdownregistry.com/api/v1/blob/9aa387eec46be1e0764c86373dd32796dc50854ecb98bd3433aed741d03d826c
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pierry/harness-kit · .claude/agents/staff-software-engineer/skills/backend/SKILL.md · Backend engineering conventions for team. Java/Kotlin servers. Project conventions in .claude/conventions/backend.md…
