fix: correct nullability, SSE, base URL, and dependency defects found by live API testing

[lightsofapollo]

Five generator defects, all found by generating a client from RunPod's published v2 OpenAPI document and exercising it against the live API.

Worth stating up front: the published spec was accurate in every case. All 31 collected live response bodies validated clean against it. Every failure was ours. Spec-diffing alone would have reported "all green" indefinitely.

Fixed

OpenAPI 3.1 nullability on required properties (openapi-generator-dsu, P0)

A property both listed in required and declared nullable via type: ["X", "null"] generated a bare T. Such a client compiles, then fails to deserialize the first real response containing null.

GET /v2/catalog/gpus and GET /v2/pods failed outright: GpuType.pool and Pod.template are null in production. Pod.startedAt was the worst latent case — null for any pod that hasn't started, taking out the whole listPods call.

The Option decision (!is_required || prop.nullable) was already correct; prop.nullable was simply never set for this form. Two call sites checked only nullable: true and the anyOf-with-null shape. This bug has now recurred once per nullability spelling added, each time by missing a site, so all three route through a single is_nullable_any() helper. Covers allOf-composed schemas too — RunPod's Pod keeps its required list inside an allOf branch.

SSE operations returned () and hung forever (openapi-generator-x9v, P1)

Operations whose success content is text/event-stream generated -> Result<(), _> and called response.text().await on an open stream, which never returns. With no default timeout on the generated client, this deadlocks the caller's task rather than erroring. Measured hung past 600s.

The streaming signal was already detected in analysis and honored by the server generator; only the client ignored it. These now return impl futures_util::Stream<Item = Result<bytes::Bytes, reqwest::Error>>. The error path still buffers, since error responses are finite.

Scoped deliberately: operations declaring both a JSON body and SSE keep their JSON contract, since those are the stream: true endpoints covered by explicit [streaming] config and changing their return type would break existing callers.

Configured base_url was ignored (openapi-generator-igg)

Worse than originally filed: generated clients started with String::new() regardless, so even users who set [http_client] base_url in TOML got a client that sent every request to a relative path. Now seeded from config, and the CLI resolves servers[0].url into config when the TOML is silent. Explicit config still wins; relative (/v1) and templated ({region}) server URLs are ignored as unusable.

Default(..) error variant was never constructed (openapi-generator-oug)

Declared on every per-operation error enum, constructed zero times — a live 422 whose body parsed cleanly still surfaced as typed: None, so the typed-errors feature silently didn't work for default responses.

Multipart clients didn't compile (openapi-generator-upz)

REQUIRED_DEPS.toml enabled reqwest's multipart feature on reqwest-middleware but not on reqwest, which is pinned default-features = false. Any spec with a file upload — OpenAI's included — produced non-compiling output.

Verification

362 tests pass. One intermediate failure was every_generation_mode_compiles_from_its_exact_dependency_fragment correctly catching that SSE output now requires futures-util; its passing confirms the streaming client compiles from its own declared fragment.

Against the live RunPod API, list_gpu_types and list_pods both failed before and now succeed. These are not trivial passes — the responses contain pool: None on 24 GPU types (alongside real Some("AMPERE_80") values) and template: None on all 8 pods, so the previously-broken path is genuinely exercised.

Not addressed here

Three findings from the same investigation remain open:

• format: float maps to f32 and loses money precision (live: 0.03 deserializes as 0.029999999329447746). RunPod's billing endpoints use double; catalog prices don't.
• problem_details() can never succeed against this API's error shape.
• x-enum-varnames is ignored for parameter enums.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
openapi-to-rust	Ready	Preview, Comment	Jul 27, 2026 1:15am