OpenAPI Cross-Tool Preflight

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

Install and get a result in one minute

1. Install OpenAPI Cross-Tool Preflight from the Visual Studio Marketplace.
2. In VS Code, choose File > New Text File, paste the harmless synthetic document below, and save it as openapi-smoke.json:

{
  "openapi": "3.0.3",
  "info": {
    "title": "Cross-tool preflight smoke fixture",
    "version": "1.0.0"
  },
  "paths": {
    "/items/{itemId}": {
      "get": {
        "responses": {
          "200": {
            "description": "ok"
          }
        }
      }
    }
  }
}

3. Press Ctrl+Shift+P (Cmd+Shift+P on macOS), type OpenAPI: Run Cross-Tool Preflight, and select that command.
4. Expect the notification OpenAPI preflight: 1 finding(s). Open View > Problems to see: [path.parameter.undeclared] Path parameter {itemId} is not declared at path or operation level.
5. The command only reports diagnostics. It does not modify or upload the document.

Normal workflow

Open an OpenAPI JSON document and run OpenAPI: Run Cross-Tool Preflight from the Command Palette. The extension analyzes the active document and reports a small, documented set of portability risks. It does not upload specifications, call a service, enable telemetry, or replace a complete OpenAPI validator.

Checks in 0.1.x

• 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.

Version 0.1.0 was published and publicly verified on Visual Studio Marketplace on 2026-08-12. The official Gallery API and browser page both resolve japan-public-data.openapi-cross-tool-preflight:

https://marketplace.visualstudio.com/items?itemName=japan-public-data.openapi-cross-tool-preflight

The public Marketplace package also passed an isolated install-and-command acceptance test on 2026-08-12. The result is retained in the project's local acceptance record.

Current boundary

Version 0.1.x accepts JSON only so the result stays deterministic and dependency-free. YAML support, remote validators, code generation, automatic rewriting, and vendor-specific profiles remain outside this MVP.