Omh Backend

---
name: "omh-backend"
description: "[omh] Hermes backend workflow: prepare server, API, and data-layer contracts — auth boundary, error paths, response shape, and schema/migration discipline — before implementation. Use when the user says: backend, back-end, back end, backend skill, server side, server-side, api design, api contract."
metadata:
  hermes:
    tags: [workflow, oh-my-hermes, planning]
    category: planning
    phase: backend-design
    role: planner
    quality_tier: backend-contract-gated
---

# Backend

This is a Hermes-native `backend` workflow skill.

## Why This Exists

`backend` gives OMH a first-class server-side workflow so Hermes can prepare auth boundaries, error paths, response shapes, and migration order without becoming the hidden runtime that executes them.

## Do Not Use When

- The request is about web UI, layout, or a design system; use `frontend`.
- The request is a security posture or threat review rather than a service design; use `security-safety-review`.
- The request is to run or judge the verification of an already-built service; use `verification-gate`.
- The request is a Rust-language change whose risk is compiler, ownership, or `unsafe` discipline; use `rust`.

## Examples

Good example:

- Prompt: Design a REST API with a Postgres schema and migrations for the billing service.
- Expected behavior: Prepare backend_service_contract/v1, auth_boundary_map/v1, error_path_table/v1, response_shape_contract/v1, and schema_migration_plan/v1, then hand off with the per-stack reference named.
- Why: The request is server-side design across an endpoint surface and its storage, before any code exists.

Bad example:

- Prompt: The migration is written, so mark the schema as migrated and the API as live.
- Expected behavior: Mark migration application, integration runs, and deployment as not_observed and name the smallest observed proof for each.
- Why: A prepared migration plan is not an applied migration, and a contract is not a running service.

## Completion Checklist

- The surface, its callers, and each caller's trust level are named.
- The auth_boundary_map/v1 states where trust changes and which check enforces it on every path.
- The error_path_table/v1 covers each failure mode with status, body shape, retryability, and redaction rule.
- The response_shape_contract/v1 is consistent across endpoints rather than per-endpoint improvisation.
- Storage changes carry an expand/backfill/switch/contract order with a rollback point per step.
- The handoff names the executor, the stack, and the per-stack reference to load first.
- Implementation, migrations, integration runs, and deployment stay observed-only.

## Recovery Notes

- If the stack or datastore is unknown, prepare the contract stack-neutral and name the stack as the one blocking input.
- If the auth model cannot be established, stop at the auth boundary gap instead of designing endpoints that assume a trust level.

## Workflow Lane

- Current lane: **Coding handoff** (`idea-to-deploy`, `llm-app-dev`, `cto-loop`, `deploy-and-monitor`, `code-review`, `build-failure-triage`, `verification-gate`, `security-safety-review`, `+13 more`) - coding owners, handoffs, review, CI, and merge evidence.
- If intent belongs to another lane, hand back to `oh-my-hermes` or name the adjacent workflow.
- Shared product, routing, compatibility, and evidence rules: `omh-routing/references/skill-common-rail.md`.

## Use When

Use when Hermes should shape a server, API, or data-layer change before implementation: authentication boundary, contract error paths, response consistency, schema and migration discipline, and the per-stack reference the executor loads first.

    Strong routing signals: `backend`, `back-end`, `back end`, `backend skill`, `server side`, `server-side`, `api design`, `api contract`, `rest api`, `graphql api`, `grpc service`, `endpoint design`, `auth boundary`, `authentication flow`, `authorization rules`, `idempotency key`, `pagination contract`, `database schema`, `postgres schema`, `schema migration`, `db migration`, `orm mapping`, `connection pool`, `message queue`, `webhook handler`, `バックエンド`, `エンドポイント設計`, `認証フロー`, `スキーマ移行`, `백엔드`, `서버 개발`, `서버 api`, `api 설계`, `인증 흐름`, `권한 체크`, `디비 스키마`, `db 스키마`, `스키마 마이그레이션`, `엔드포인트 설계`, `后端`, `後端`, `接口设计`, `认证流程`, `数据库迁移`

## Catalog Metadata

Category: `planning`
Phase: `backend-design`
Hermes role: `planner`
Quality tier: `backend-contract-gated`
Reasoning demand: `standard`

Quality bar:

- Name the surface, its callers, and their trust level before any endpoint or table is designed.
- Load `references/service-contract.md` and fill the auth boundary, error-path table, and response-shape rules from it rather than improvising a per-endpoint shape.
- When the change touches storage, load `references/schema-migration.md` and order the migration as expand, backfill, switch, contract, with the rollback point named per step.
- Hold the `api` product-family expectations — authentication boundary, contract error paths, response consistency — as the standing bar for every prepared endpoint.
- Name the per-stack reference the executor must read first; the stack is a routing input, not a detail discovered mid-implementation.
- Keep implementation, migration application, integration runs, load testing, and deployment as observed-only evidence.

Handoff policy:

Keep the service contract, auth boundary, error-path table, and migration plan in Hermes. Record code changes, running servers, applied migrations, integration runs, and load results only from executor or wrapper observed evidence.

Required inputs:

- the service, endpoint, or data surface being changed
- callers and their trust level (public, partner, internal, machine)
- language, framework, and datastore when known
- authentication and authorization model in force
- existing schema and migration tooling
- backward-compatibility and rollout constraints
- observed integration or load evidence for completion claims

Expected outputs:

- backend_service_contract/v1
- auth_boundary_map/v1
- error_path_table/v1
- response_shape_contract/v1
- schema_migration_plan/v1 when the change touches storage
- backend_implementation_handoff/v1
- observed_integration_evidence/v1 when observed

Artifact expectations:

- backend_service_contract/v1 names each endpoint or job, its caller class, request and response shapes, and its idempotency and pagination rules
- auth_boundary_map/v1 states where an untrusted caller becomes a trusted one, and which check runs on each path
- error_path_table/v1 pairs every failure mode with its status/code, body shape, retryability, and log/redaction rule
- response_shape_contract/v1 keeps success and error envelopes consistent across the surface instead of per-endpoint improvisation
- schema_migration_plan/v1 orders expand, backfill, switch, and contract steps with the rollback point for each
- integration runs, applied migrations, load numbers, and deployment only when observed

Safety rules:

- Do not claim implementation, a running service, an applied migration, a passing integration suite, or a deployment from a prepared backend contract.
- Require the auth boundary before endpoint work: an endpoint whose caller trust level is unnamed is not ready for handoff.
- Require the error-path table before the happy path is called complete; an unlisted failure mode is a gap, not a default.
- Treat a destructive or non-reversible migration step as a blocker until an explicit rollback point and backfill order exist.
- Never place secrets, tokens, or connection strings in the contract, examples, or handoff text.
- Do not call databases, HTTP services, LLM, or network endpoints from OMH core.

## Runtime Evidence

Preferred harness for this skill: `coding-handling`.

```sh
omh runtime record --skill backend --harness coding-handling --status started
```

Record observed delegation results; otherwise return `not_available` or `not_observed`.
Prepared OMH routing is not execution, review, CI, merge-readiness, or merge evidence.
- Treat wrapper memory/context summaries as advisory local context, not proof of opaque Hermes memory reads or changes.
Preserve workflow intent and stop conditions; verify before claiming completion.

Use Hermes-native subagent/delegation features when available: native subagents -> Hermes delegation when available, otherwise sequential lanes.

Shared product, compatibility, topology, memory, harness, and execution rules: `omh-routing/references/skill-common-rail.md`. Load it when applicable; otherwise name an unavailable capability.