Migrate to oas3 (OpenAPI 3.1 support) + header param Option fix

CHANGELOG.adoc

@@ -22,6 +22,15 @@ https://github.com/oxidecomputer/progenitor/compare/v0.13.0\...v0.14.0[Full list
 * Add CliCommand::operation_id() to get the original operationId (#1336)
 * Treat connection upgrade (HTTP 101) as normal success. (#1320)
 
+* Replace the `openapiv3` crate with `oas3`. Progenitor now targets
+  OpenAPI 3.1 documents; 3.0 documents continue to parse but their
+  `nullable: true` annotations are dropped silently. Bundled fixtures
+  under `sample_openapi/` have been migrated to 3.1 (`type: ["...",
+  "null"]`, numeric `exclusiveMinimum`/`exclusiveMaximum`). Regenerate
+  any 3.0 specs to 3.1 if their nullability is semantically
+  significant.
+
+
 == 0.13.0 (released 2026-02-24)
 
 https://github.com/oxidecomputer/progenitor/compare/v0.12.0\...v0.13.0[Full list of commits]

Cargo.toml

@@ -39,14 +39,14 @@ heck = "0.5.0"
 http = "1.4.0"
 hyper = "1.9.0"
 indexmap = "2.14.0"
-openapiv3 = "2.2.0"
+oas3 = "0.21.0"
 percent-encoding = "2.3.2"
 proc-macro2 = "1.0.106"
 quote = "1.0.45"
 rand = "0.10.1"
 regex = "1.12.3"
 regress = "0.11.1"
-reqwest = { version = "0.13.3", default-features = false, features = ["json", "query", "stream"] }
+reqwest = { version = "0.12.28", default-features = false, features = ["json", "stream"] }
 rustfmt-wrapper = "0.2.1"
 schemars = { version = "0.8.22", features = ["chrono", "uuid1"] }
 semver = "1.0.28"

cargo-progenitor/Cargo.toml

@@ -7,7 +7,7 @@ license.workspace = true
 description = "A cargo command to generate a Rust client SDK from OpenAPI"
 repository = "https://github.com/oxidecomputer/progenitor.git"
 readme = "../README.md"
-keywords = ["openapi", "openapiv3", "sdk", "generator"]
+keywords = ["openapi", "oas3", "sdk", "generator"]
 categories = ["api-bindings", "development-tools::cargo-plugins"]
 
 default-run = "cargo-progenitor"
@@ -23,7 +23,7 @@ clap = { workspace = true }
 clap-cargo = { workspace = true }
 env_logger = { workspace = true }
 expectorate = { workspace = true }
-openapiv3 = { workspace = true }
+oas3 = { workspace = true }
 rustfmt-wrapper = { workspace = true }
 serde_json = { workspace = true }
 serde_yaml = { workspace = true }

cargo-progenitor/src/main.rs

@@ -8,7 +8,7 @@ use std::{
 
 use anyhow::{Result, bail};
 use clap::{Parser, ValueEnum};
-use openapiv3::OpenAPI;
+use oas3::Spec;
 use progenitor::{GenerationSettings, Generator, InterfaceStyle, TagStyle};
 use progenitor_impl::space_out_items;
 
@@ -304,7 +304,7 @@ pub fn dependencies(builder: Generator, include_client: bool) -> Vec<String> {
     deps
 }
 
-fn load_api<P>(p: P) -> Result<OpenAPI>
+fn load_api<P>(p: P) -> Result<Spec>
 where
     P: AsRef<Path> + std::clone::Clone + std::fmt::Debug,
 {

progenitor-impl/Cargo.toml

@@ -12,7 +12,7 @@ readme = "../README.md"
 heck = { workspace = true }
 http = { workspace = true }
 indexmap = { workspace = true }
-openapiv3 = { workspace = true }
+oas3 = { workspace = true }
 proc-macro2 = { workspace = true }
 quote = { workspace = true }
 regex = { workspace = true }

progenitor-impl/src/cli.rs

@@ -3,7 +3,7 @@
 use std::collections::BTreeMap;
 
 use heck::ToKebabCase;
-use openapiv3::OpenAPI;
+use oas3::Spec;
 use proc_macro2::TokenStream;
 use quote::{format_ident, quote};
 use typify::{Type, TypeEnumVariant, TypeSpaceImpl, TypeStructPropInfo};
@@ -24,7 +24,7 @@ struct CliOperation {
 
 impl Generator {
     /// Generate a `clap`-based CLI.
-    pub fn cli(&mut self, spec: &OpenAPI, crate_name: &str) -> Result<TokenStream> {
+    pub fn cli(&mut self, spec: &Spec, crate_name: &str) -> Result<TokenStream> {
         validate_openapi(spec)?;
 
         // Convert our components dictionary to schemars
@@ -40,15 +40,15 @@ impl Generator {
         let raw_methods = spec
             .paths
             .iter()
-            .flat_map(|(path, ref_or_item)| {
-                // Exclude externally defined path items.
-                let item = ref_or_item.as_item().unwrap();
-                item.iter().map(move |(method, operation)| {
-                    (path.as_str(), method, operation, &item.parameters)
-                })
+            .flat_map(|paths| paths.iter())
+            .flat_map(|(path, item)| {
+                item.methods()
+                    .into_iter()
+                    .map(move |(method, operation)| (path.as_str(), method, operation, item))
             })
-            .map(|(path, method, operation, path_parameters)| {
-                self.process_operation(operation, &spec.components, path, method, path_parameters)
+            .map(|(path, method, operation, item)| {
+                let method_str = method.as_str().to_ascii_lowercase();
+                self.process_operation(operation, spec, path, &method_str, &item.parameters)
             })
             .collect::<Result<Vec<_>>>()?;