feat: expand corpus protocol and multipart coverage

[lightsofapollo]

Summary

Expands the real-spec corpus follow-up with bounded, contract-driven support for several wire patterns that previously prevented generated clients and Axum servers from compiling or interoperating:

• symmetric AWS query-protocol serialization and reconstruction, explicitly gated by info.x-providerName: amazonaws.com;
• typed multipart request models on generated clients and servers, preserving exact binary bytes;
• multipart request-size limits and normal generated JSON Schema validation;
• OpenAPI simple/non-exploded array headers used by S3;
• narrow embedded path-parameter affixes such as {api}.json, with canonical Axum route-collision rejection.

Protocol and safety details

AWS query conventions

• Keeps OpenAPI wire names separate from Rust-safe identifiers.
• Uses one-based numeric indexes and BTreeMap<usize, _> reconstruction.
• Preserves present-empty nested arrays, objects, and indexed object entries.
• Keeps client serialization and server reconstruction driven by matching bounded metadata.
• Rejects excessive nesting, ambiguous wire namespaces, unsupported additionalProperties, and duplicate/conflicting representations instead of guessing.
• Does not apply AWS outer-prefix conventions to ordinary OpenAPI form+explode objects.

Multipart

• Generated clients accept generated request-body models and construct reqwest::multipart::Form internally.
• Generated Axum servers extract supported bounded object schemas into the same generated models.
• Preserves raw binary bytes for BinaryStrategy::Bytes and BinaryStrategy::VecU8; supports textual BinaryStrategy::String symmetrically.
• Supports signed and unsigned scalar parsing, including uint64 above i64::MAX.
• Runs the normal generated request-body JSON Schema validator after reconstruction.
• Applies server.validation.max_body_bytes with Axum DefaultBodyLimit.
• Avoids per-byte serde_json::Value expansion: binary payloads stay in dedicated byte slots and are restored into the typed model after validation.
• Rejects duplicate, unknown, missing, malformed, unresolved, cyclic, array/object, and open additionalProperties multipart shapes deterministically.
• Emits Axum's multipart feature only when required.
• Covers validation-disabled generation, all public binary strategies, and embedded-affix paths with exact generated dependency-fragment compilation.

Headers and routes

• Emits S3-style simple arrays as one comma-separated header and reconstructs typed values server-side.
• Preserves referenced header-item models during pruning.
• Supports one parameter plus literal affixes within a path segment.
• Canonicalizes dynamic capture names when checking method/route collisions, so {id} and {name} cannot evade collision detection.

Corpus and real-spec verification

The rebuilt generator was run across all 241 corpus entries:

• 226/241 fully successful;
• client generation and operation listing succeeded for all 241;
• 15 server-generation failures are intentional bounded rejections rather than inferred/unsafe support.

Real-spec spot checks covered Adobe AEM, api.video, Amazon DocumentDB, Amazon S3, and apis.guru.

MinIO smoke test

A regenerated S3 client successfully completed:

• ListBuckets
• CreateBucket
• PutObject
• GetObject
• exact upload/download payload equality
• cleanup

Verification

• cargo test --all-features
• cargo fmt --all -- --check
• cargo clippy --all-features -- -D warnings
• RUSTDOCFLAGS='-D warnings' cargo doc --no-deps --all-features
• CONFORMANCE_REPORT=1 cargo test --test conformance --test conformance_json_schema
• conformance reports unchanged
• cargo build --quiet --bin openapi-to-rust
• generated multipart client/server runtime round trip
• generated AWS query client/server runtime round trip
• exact-dependency generated compilation for all multipart binary strategies with validation disabled and an embedded-affix path
• full 241-spec corpus probe
• repeated MinIO S3 smoke test with exact payload equality
• independent security/logic review, including remediation and clean re-review of the final linkage regression

cargo clippy --all-targets --all-features -- -D warnings remains affected by established test/example unwrap/expect lint failures; the CI-equivalent library/all-feature clippy command above is clean.

Review notes

The query and multipart implementations are intentionally bounded. This PR rejects shapes for which client/server symmetry, extraction closure, validation semantics, or memory behavior cannot be guaranteed. Please review those generation-time rejection boundaries as part of the API contract.

Draft for human review; no auto-merge.

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Project	Deployment	Actions	Updated (UTC)
openapi-to-rust	Ready	Preview, Comment	Jul 29, 2026 5:48am