openapi-32-querystring-parameter.md

title	OpenAPI 3.2: Support querystring parameter location
parentIssue	1673
labels	enhancement openapi-3.2
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OpenAPI 3.2 adds querystring as a new value for the in field of a Parameter Object. Unlike the existing query (which targets a single named query parameter), querystring treats the entire query string as a single field and allows it to be parsed with a schema, similar to how requestBody works for request bodies. This simplifies complex query-string APIs such as OData or OpenSearch.

Current state

src/typescript-generator/parameters-type-coder.ts generates typed objects for query, path, header, and cookie parameters. A querystring parameter would currently be silently ignored, and the dispatcher's parameter-extraction logic does not handle it.

Proposed changes

• Handle in: querystring in ParametersTypeCoder (src/typescript-generator/parameters-type-coder.ts) to generate a typed querystring property on the $ argument
• Update the dispatcher's parameter-extraction logic (src/server/dispatcher.ts) to parse the raw query string against the schema and populate $.querystring
• Ensure the generated TypeScript type for $.querystring reflects the schema defined in the parameter object

Acceptance criteria

• A parameter with in: querystring generates a querystring property on the typed $ argument
• The generated TypeScript passes tsc --noEmit without errors
• At runtime, $.querystring contains the parsed query string matching the defined schema
• Existing query, path, header, and cookie parameters are unaffected
• Unit tests cover type generation and runtime extraction for querystring parameters