Backend Engineering — Edho Ferdian Mode

Where this sits

• api-design-edho-ferdian decides the contract at the boundary.
• data-layer-patterns-edho-ferdian decides the storage behind it.
• This skill is the middle: how the code between them is layered, how it fails, and how it defers work.
• code-review-edho-ferdian reviews the result — in particular silent-failure-lens.md, which is the review-side mirror of references/error-and-resilience.md here. Cross-reference, never restate.

References

• references/error-and-resilience.md

• references/llm-pipelines.md — regex-first parsing with confidence-scoring as the LLM gate, plus cost-aware model routing, budget tracking, retry policy, and prompt caching for pipelines that call an LLM API.

• references/scheduled-collection.md — unattended collect/enrich/store pipelines (scrapers, feed pollers, report builders): source selection, per-source failure isolation, LLM-enrichment batching and fallback, prompt-injection rules for untrusted scraped content, idempotent upsert, and cron/alerting operations. Covers the background-job concerns (idempotency, dead-letter-style backfill, run scheduling) for this class of job — see the note below for what it does not cover.

• references/nestjs.md — NestJS project structure (common/, config/, modules/<fitur>/ with module-local DTOs), canonical bootstrap (global ValidationPipe, ClassSerializerInterceptor, HttpExceptionFilter), env validation at boot, repository/transaction placement, and background jobs/event consumers in their own modules. Not speculative — this is the framework behind ghostfolio, a real project in Edho's stack.

• references/rails.md — Rails 7.1+/8.x authoring: directory contract, when to extract a service/form/query object or ViewComponent, service result objects and transactions, ActiveRecord discipline (eager loading, callbacks, no default_scope), idempotent jobs, Hotwire, and the Rails 8 Solid stack. Review and build-failure lenses for Ruby live in language-code-review-edho-ferdian and build-fix-edho-ferdian.

• references/layering-and-boundaries.md — ports & adapters (hexagonal architecture) with a framework-agnostic dependency-direction diagram, the repository-vs-service layer split with a misplaced-concern test, the composition root (NestJS DI and hand-wired bootstrap variants), a six-step migration playbook for entangled/legacy code, and a checklist for adding a new integration cleanly through the same port/adapter seam.

• references/jobs-and-queues.md — generic queue-backend reference, distinct from references/scheduled-collection.md (which covers the scheduled-collection job shape specifically): backend choice (BullMQ vs SQS vs Postgres-based pg-boss/graphile-worker), worker-pool concurrency sizing, retry/backoff classification, dead-letter queues generically, job idempotency keys, and queue observability.

External docs (fixed — see skill-authoring-edho-ferdian's canonical contract)

Before using a fast-moving or rarely-touched framework/queue/ORM API surface (new integration, version upgrade, NestJS/BullMQ/pg-boss specifics), resolve it live via Context7 rather than from memory. Full contract: skill-authoring-edho-ferdian §9.

Surgical changes (fixed — see skill-authoring-edho-ferdian's canonical contract)

This skill inherits the default as-is: when extending or fixing an existing service, error path, or job, change only what the task requires — don't relayer or restructure adjacent, already-working code as a side effect. Full contract: skill-authoring-edho-ferdian §10.

Language routing (fixed — see skill-authoring-edho-ferdian's canonical contract)

Communication to the user in Bahasa Indonesia; code, comments, and any generated files in English — fixed, never ask. Full contract: skill-authoring-edho-ferdian §7.