---
id: review-001-openapi-loud-degradation
name: Loud unsupported-OpenAPI-feature handling (OAI-06)
status: pending
depends_on: []
scope: narrow
risk: low
impact: component
level: implementation
tags: [adapters, review-001, from-openapi, follow-up]
---

## Description

Review 001 finding OAI-06 — deliberately deferred during decomposition
("revisit after the input-schema work"): unsupported OpenAPI features
still degrade **silently**, each producing an op that misbehaves only at
call time (verified still true post-remediation):

- `default`/wildcard response keys become
  `ErrorDefinition { code: "HTTP_0", http_status: None }`
  (`from_openapi.rs:build_error_schemas`, ~:238-243) — entries that never
  match a real status.
- `trace` ops silently skipped (`openapi_spec.rs`); `servers` overrides
  ignored; parameter `style`/`explode` unsupported and silent (arrays
  serialize `"[1,2]"`); a `default`-declared SSE stream is missed by
  `detect_op_type` and would return one giant text string.

Since OAI-03's fix, the codebase already has the right pattern —
`in: cookie` fails import with a clear `SchemaParse` naming the feature
and the remediation. Extend that posture: unsupported features that
would produce a wrong-behaving op **fail import loudly** (or degrade in
a way that is documented, tested, and visibly warned), never silently.

Per-feature decision, implementer's judgment with the review's map:
reject at import (cookie-style, preferred for anything that changes
wire semantics: `style`/`explode` non-default forms, `servers` override
on a non-matching base), or support (HTTP_0's real fix is mapping
`default` → a documented catch-all code or dropping it with a warning
— pick one and test it), or document-as-inert (`trace` skip is
defensible if logged).

## Acceptance Criteria

- [ ] A spec using each unsupported feature either imports with a documented, warned, tested behavior or fails import with a feature-naming error (tests per feature)
- [ ] `HTTP_0` no longer emitted (default responses mapped or dropped loudly) — `/search` never advertises a code that can't match
- [ ] `style`/`explode` non-default forms do not silently mis-serialize arrays
- [ ] `cargo test` and `cargo clippy --all-targets -- -D warnings` pass

## References

- docs/reviews/001-initial-implementation-review.md (Part E, OAI-06)
- tasks/adapters/review-001-input-schema-enforcement.md (the loud-unsupported pattern to extend)

## Notes

> Agent fills during implementation. Deferred from the original
> decomposition for staleness reasons; unblocked once OAI-02/03/07/09
> landed (they did). Scope guard: this is import-time fidelity, not
> new feature support — do not implement `servers` overrides or style
> serialization here.

## Summary

> Filled on completion.