OpenAPI Cross-Tool Preflight

A local-only validation MVP for API maintainers whose OpenAPI document validates in one tool but renders or generates differently in another.

The extension contributes one command: OpenAPI: Run Cross-Tool Preflight. It analyzes the active JSON document and reports a small, documented set of portability risks. It does not upload specifications, call a service, or enable telemetry.

Checks in 0.1.0

• OpenAPI version is 3.0.x or 3.1.x.
• Every {path_parameter} is declared at path or operation level.
• $ref siblings are flagged because older tooling may ignore them.
• OpenAPI 3.1 schema examples and nullable portability risks are flagged.

This is a compatibility preflight, not a complete OpenAPI validator.

Verify locally

Set-Location C:\Sumire\10-projects\openapi-cross-tool-preflight
npm run check
npm test

The command adapter is covered by deterministic tests. A real Extension Development Host smoke test also passed on 2026-08-11. The approved public package is bound to the japan-public-data Marketplace publisher and remains telemetry-free.

Try in VS Code after local packaging

Open a JSON OpenAPI document and run the command from the Command Palette. The MVP currently accepts JSON only so the first validation result stays deterministic and dependency-free.