Lerianstudio Ring Ring

Adopt the lib-commons Huma OpenAPI Wrapper

When to use

• A Go service needs code-first OpenAPI 3.1 over Fiber (Huma) with RFC 9457 application/problem+json errors
• User asks to "adopt the lib-commons OpenAPI/problem wrapper", "use the shared Huma wrapper", "standardize error responses on RFC 9457"
• A service already carries a local copy of the wrapper (internal/shared/adapters/openapi, shared/openapi, shared/humaerr, a hand-rolled huma.NewError override) and should move onto the shared lib-commons/v5/commons/net/http/{openapi,problem}
• A service is still on swaggo/swag (Swagger 2.0) and is migrating to Huma

Skip when

• Service is not a Go project
• Task does not involve an HTTP API / OpenAPI spec
• The service genuinely needs a bespoke error envelope that is NOT RFC 9457 (rare; challenge it first)
• Documentation-only or non-code task

You orchestrate. Agents implement. NEVER use Edit/Write/Bash on Go source files — all code changes go through Task(subagent_type="ring:backend-go"). TDD mandatory for implementation gates (RED → GREEN → REFACTOR). The orchestrator owns git (commit/push/PR/release) and NEVER commits without the user's go-ahead.

Architecture

The wrapper is two packages in lib-commons/v5 (minimum v5.6.0):

openapi.New(app, group, cfg) constructs the Fiber-v2 Huma API via humafiber.NewV2WithGroup (the default humafiber.New targets Fiber v3 — wrong major), strips Transformers/OnAddOperation/CreateHooks, and clears the auto-mounted /openapi.json + /docs (auto-mount is a latent production exposure — the spec must be served explicitly and gated). Config{Title, Version, Description, Servers}.

openapi.ServeSpec(app, api, logger, prefix, title) mounts {prefix}/openapi.json, {prefix}/openapi.yaml, {prefix}/docs (Scalar UI). It normalizes prefix (leading slash, no trailing) and HTML-escapes the docs-page title and spec URL. Gate this behind the service's Swagger.Enabled flag — never serve unconditionally.

openapi.DeclareBearerAuth(api) registers the BearerAuth security scheme component (components.securitySchemes) so Security references resolve — it does NOT attach the requirement to anything. The scheme component alone advertises ZERO secured operations. To make the spec say "auth required" you MUST also attach a requirement, one of:

• Global default (covers every op in one line, drift-safe): api.OpenAPI().Security = []map[string][]string{{"BearerAuth": {}}} right after openapi.New.
• Per-operation: Security: []map[string][]string{{"BearerAuth": {}}} on each huma.Operation.

DeclareBearerAuth without a requirement is the classic regression: a JWT-enforced API whose spec advertises every endpoint as public. Public endpoints (no auth middleware at runtime) must override the global default with an explicit empty requirement: Security: []map[string][]string{} on the operation — a non-nil empty slice, which Huma renders as security: [] because Operation.Security marshals with omitNil (Go json:"...,omitempty" would drop it and silently re-inherit the global default). Getting this wrong makes the spec lie about which routes need a token — see also the constraint-as-validation caveat under Dependency facts.

problem.Install() is the crux. It is a sync.Once override of the process-global huma.NewError, so EVERY error Huma builds — domain errors via MapError and the framework's own validation/404/422 errors — becomes a *problem.Detail. Merge semantics:

• status >= 500: body scrubbed to the static "internal error", NO errs folded. This is the central info-leak guard — even a careless huma.Error500(rawErr.Error()) cannot leak an internal cause.
• status < 500: msg passes through and errs fold into Errors[] in order (skip nil, honor huma.ErrorDetailer) — native 422 field errors are preserved.

problem.MapError(err, codeOf, statusOf, fallbackCode) is the per-rail flex seam — the one place each service injects its own taxonomy:

• codeOf func(error) (code, msg string, ok bool) — extract a domain code; ok=false → unrecognized → sanitized 500 carrying fallbackCode.
• statusOf func(code string) int — map code → HTTP status.
• fallbackCode — code carried when the error is nil/unrecognized.
• A service WITH a code taxonomy passes real callbacks + a fallback (e.g. "SPB-9000"); a bare service passes an empty fallback and code is dropped (omitempty).

problem.Detail embeds huma.ErrorModel + an omitempty Code. Services that never set a code emit a bare RFC 9457 body; coded errors mapped through MapError carry the machine code in Code + a flat Type URI (BaseURI + "/" + code). Type is set only on the MapError coded path — framework-built errors (native 422/404 via Install) keep Type at about:blank with empty Code.

Dependency facts (do not re-litigate)

• huma version MUST match what the pinned lib-commons build uses (danielgtaylor/huma/v2 v2.38.0 at v5.6.0). A mismatch is module-graph skew that the security-scan/SBOM gate will flag.
• humafiber drags gofiber/fiber/v3 as an indirect dep — this is EXPECTED, not a bug. humafiber is one package importing both Fiber majors; Go compiles the whole package, so importing it for the v2 funcs pulls v3 into the graph. Only the v2 path compiles into the binary. govulncheck stays quiet (v3 unreachable); Trivy/SBOM may flag future fiber/v3 CVEs — a waivable false positive, NOT a reason to avoid the wrapper.
• Test the API through the real *fiber.App via app.Test, not humatest (the humatest adapter diverges on Unwrap).
• Huma schema-constraint struct tags are VALIDATION, not documentation. minLength/maxLength/minItems/maxItems/minimum/maximum/pattern/enum are enforced by Huma at the framework layer — a violating request is rejected with a 422 before the handler runs. Adding one to "make the spec match the runtime limit" silently relocates rejection from the handler (its domain 400/coded error) to Huma's 422, changing the error contract and making the handler's coded path unreachable for that field. The runtime limit is usually already enforced by a validate: tag (go-playground); duplicating it as a Huma constraint moves the enforcement layer. Treat constraint tags as a behavioral change (needs error-contract + test updates), never a doc-only edit. By contrast doc:/example: tags ARE pure documentation and safe to add freely. Decisive test: if a unit test's expected status flips, it's behavioral.

Mandatory agent instruction (include in EVERY dispatch):

Use the canonical imports github.com/LerianStudio/lib-commons/v5/commons/net/http/openapi and .../problem. Do NOT reintroduce a local openapi/humaerr wrapper or a hand-rolled huma.NewError override — problem.Install() owns that globally. problem.Install() MUST be called before ANY Huma operation is registered, on BOTH the runtime API and any spec-gen API, or the runtime error bodies and the committed spec diverge. Match the huma version the pinned lib-commons uses (v2.38.0 @ v5.6.0). The indirect fiber/v3 is expected — do not try to remove it. Serve the spec only via openapi.ServeSpec, gated on the Swagger-enabled flag. Never rely on Huma auto-mount. If the API uses bearer auth, DeclareBearerAuth alone advertises nothing — attach a security requirement (global api.OpenAPI().Security default or per-op) and override genuinely-public ops with Security: []map[string][]string{}. Make the generated spec rich, not hollow: doc: + example: tags on request/response DTO fields, and info.Contact/info.License + top-level Tags (with descriptions) on the document. Do NOT add minLength/maxLength/maxItems etc. as a doc gesture — those are enforced validation (see Dependency facts). Preserve the service's existing per-rail code taxonomy verbatim — only rewire the wrapper call into problem.MapError. TDD: RED → GREEN → REFACTOR for every gate. Test via app.Test, not humatest.

Gate Overview

Gates execute sequentially. Any surviving local wrapper or hand-rolled huma.NewError override = NON-COMPLIANT = gates cannot be skipped.

Gate 0: Stack Detection + Compliance Audit

Orchestrator executes directly.

grep -n "lib-commons/v5" go.mod                                  # version (need >= v5.6.0)
grep -n "danielgtaylor/huma" go.mod                              # huma version (match the lib build)
grep -rn "humafiber\|huma.Register\|huma.Get\|huma.Post" internal/ cmd/   # existing Huma usage
grep -rln "huma.NewError" internal/ cmd/                         # hand-rolled overrides (must go)
grep -rn "shared/openapi\|shared/humaerr\|adapters/openapi" --include='*.go' .  # LOCAL wrapper (migration mode)
grep -rn "swaggo\|gofiber/swagger\|// @" --include='*.go' . docs/    # legacy swaggo (migrating from 2.0)
grep -rn "ServeSpec\|openapi.New\|problem.Install" internal/ cmd/  # already partially adopted?
grep -rn "Swagger.Enabled\|SWAGGER_ENABLED" internal/            # the serving gate flag

Mode detection:

• Migration mode — a local openapi/humaerr package or a hand-rolled huma.NewError override exists → Gate 6 runs.
• Greenfield mode — Huma not yet wired (or swaggo only) → Gate 6 skipped, Gate 3 builds fresh.

Compliance audit (if any Huma code detected):

• problem.Install() present on the runtime path AND the spec-gen path
• No surviving local wrapper / hand-rolled huma.NewError override
• Spec served only via ServeSpec, gated; no auto-mount
• huma version matches the lib-commons build

Gate 2: Version + huma alignment

Ensure go.mod requires lib-commons/v5 >= v5.6.0 and danielgtaylor/huma/v2 at the version that lib-commons build uses. go mod tidy; expect fiber/v3 to appear/stay indirect (expected). If validating against an unreleased wrapper version, use a local replace => ../lib-commons (see Gate 11) — never pin a pre-release for merge.

Gate 3: openapi.New + problem.Install — BOTH paths

The single most common defect is wiring problem.Install() on only one path. Huma resolves the error response schema at operation-registration time, and Install swaps a process-global, so it must run before every huma.Register/Get/Post on:

1. the runtime API (bootstrap/routes), and
2. every spec-gen entrypoint (the cmd/huma-spec-style builder that writes the committed openapi.yaml).

If the two disagree on whether Install ran, the served error bodies and the committed spec diverge. openapi.New itself registers no operations (auto-mount cleared), so the correct order is: api := openapi.New(...) → problem.Install() → register operations.

Gate 4: Per-rail problem.MapError

Replace the service's existing domain-error→HTTP translation with problem.MapError, preserving its code taxonomy verbatim. Wire codeOf/statusOf/fallbackCode:

• Coded rail: codeOf reads the service's domain-error code, statusOf is its code→status table, fallbackCode is the house "unknown" code.
• Bare rail: empty fallbackCode; Code is omitted from the body. Verify the mapped status semantics are unchanged from before (this gate is a rewire, not a re-design).

Gate 5: ServeSpec (gated) + bearer auth (scheme + requirement + public overrides)

Mount the spec via openapi.ServeSpec(app, api, logger, prefix, title) behind the Swagger-enabled flag. Confirm the served paths match the service's existing convention (no path drift).

If the API uses bearer auth, wiring it correctly is THREE steps, not one:

1. openapi.DeclareBearerAuth(api) before registration — registers the scheme component.
2. Attach the requirement, or the spec advertises every op as public: a global default api.OpenAPI().Security = []map[string][]string{{"BearerAuth": {}}} (one line, covers all ops, drift-safe) or per-operation Security on each huma.Operation.
3. Override genuinely-public ops (no auth middleware at runtime) with Security: []map[string][]string{} (non-nil empty → Huma renders security: []). Skipping this makes the spec claim a token is required where it isn't.

Cross-check the spec's security against the real middleware chains: every op the spec marks secured must actually enforce auth at runtime, and every public route must carry the empty override. A spec that disagrees with the middleware is a contract bug, not cosmetics.

Gate 5.5: Spec richness + document metadata

Only when the service advertises a spec to clients. A spec that lints but carries hollow schemas is low-value. Ensure:

• Field documentation: doc: and example: tags on request/response DTO fields (the leaf structs Huma reflects — for a Body <Type> marker the leaf lives in the sibling DTO file, not the *_huma.go wrapper; only structs reachable from a registered huma.Register Input/Output or r.Schema(reflect.TypeOf(...)) are reflected, so tags on inert internal structs do nothing — confirm each example appears in the regenerated spec).
• Document metadata: info.Contact, info.License, document Servers (via openapi.Config.Servers), and a top-level Tags array whose entries carry descriptions covering every operation-tag string in use. Contact/License/Tags are set post-New (api.OpenAPI().Info/.Tags); like every spec mutation they must be applied identically on BOTH the runtime and spec-gen assembly paths if the service has two (the drift/byte-identity gate enforces this).
• Do NOT reach for minLength/maxLength/maxItems to "enrich" — those are enforced validation, not docs (see Dependency facts). doc:/example: are the documentation surface.

Gate 6: Delete the local wrapper (migration mode)

Remove the local openapi/humaerr packages and any hand-rolled huma.NewError override. Then:

• grep -rn for the old import paths/symbols → must be EMPTY in Go code.
• Relocate any cross-package parity/contract test out of the deleted dirs; retarget renamed schema component names.
• Fix stale doc-comments AND live docs (READMEs/architecture docs) that point at the removed packages — the diff-stat won't show these; grep for them.

Gate 7: Regenerate spec + prove rename-only

Regenerate the committed OpenAPI spec(s). The diff should be only the error-schema rename (ErrorModel→Detail, or a local ProblemDetail→Detail) + the additive code property + $ref re-targets. Do not trust the diff-stat — an alphabetical component re-sort inflates insert/delete counts. Prove rename-only with an order-independent comparison:

diff <(git show HEAD:path/to/openapi.yaml | sed 's/ProblemDetail/Detail/g' | sort) <(sort path/to/openapi.yaml)
# EMPTY => pure rename (HEAD+rename equals worktree as a line multiset)

Confirm/refresh the committed-spec drift gate so a stale spec fails CI.

Gate 8: Tests

Build + unit -race + the spec-drift gate. Error-policy assertions (the highest-value tests in the migration): a forced >=500 asserts detail == "internal error" AND Errors == nil (no leaked cause); a <500 validation error keeps its Errors[] field list. Note: huma.ErrorModel.Type is omitempty and is set only on the MapError coded path — assert type only on coded-domain responses, never on native 422/404 (where it stays about:blank/absent). Always assert title/status/detail/code.

Gate 11: Release / pin discipline (cross-repo, only if the wrapper version is unreleased)

Relevant only when this adoption rides an unreleased lib-commons wrapper change (you modified the wrapper too). The shared security-scan gate reds any PR pinned to a pre-release version. So:

1. Validate the consumer against the beta via a local replace => path/to/lib-commons (the require can lag; replace overrides resolution).
2. Cut the lib-commons stable tag (develop→main release PR; semantic-release auto-tags) BEFORE pinning any consumer.
3. Drop the replace, bump require to the stable tag (a stale require masked by a replace will break the build when the replace is removed — bump them together), go mod tidy && go mod verify.
4. Only then open/merge the consumer PR — now the pre-release pin gate passes. Intra-repo replace directives (module wiring within a multi-module repo) are fine and version-scoped; the gate targets pre-release versions, not the existence of a replace.

Severity Reference

Related

Complementary: ring:using-lib-commons (the broader non-observability lib-commons surface; this wrapper lives under its commons/net/http) Similar: ring:migrating-to-lib-systemplane, ring:migrating-to-lib-observability Skills orchestrated:

• ring:codebase-explorer
• ring:visualizing
• ring:backend-go
• ring:reviewing-code

Source: LerianStudio/ring — distributed by TomeVault.