docs: clarify compiler setup for TypeScript 7 applications

[shreyam1008]

Changes

Correct the setup commands in the quickstart and Node API guide to install typescript@5, matching the currently published openapi-typescript@7.13.0 peer range. Installing an unqualified typescript now selects TypeScript 7, whose root module does not provide the classic compiler API used by the generator.

For TS7 applications, explain how to keep the native application compiler unchanged and run generation in a separate tooling package. Custom transforms and returned AST nodes must share the generator's JS compiler; the generated source is the boundary between that tool and the TS7 application.

Related to #2841. This is a documented workaround, not native TS7 API support, and does not close the underlying compatibility issue. It does not duplicate #2818's proposed TS6 peer-range change or change compiler ownership/runtime dependencies.

How to Review

Only docs/introduction.md and docs/node.md change. No package, lockfile, runtime, generated output, or AST contract changes.

Verified locally with Node 22.12.0 and Bun 1.4.0 using two independent package directories:

• Application: typescript@7.0.2.
• Tooling: published openapi-typescript@7.13.0 and typescript@5.9.3.
• Generate from a small local OpenAPI 3.0.3 schema with a required string name and optional date-time createdAt.
• Compile a consumer of the generated components type using the application's TS7 compiler, --noEmit --strict --skipLibCheck false; a valid assignment passes and an intentional numeric-name assignment is rejected via @ts-expect-error.
• Both ESM and CJS programmatic generation pass. An ESM transform returns ts.factory.createTypeReferenceNode("Date"); printing yields createdAt?: Date. Returned nodes can be inspected with ts.isInterfaceDeclaration.
• Assert generator and callback script resolve exactly the same typescript module, version 5.9.3.
• git diff --check passes.

The complete documentation site build and repository-wide suites were not run for this small Markdown correction. No claim of testing native TS7 AST interoperability is made.

Microsoft's explanation: https://devblogs.microsoft.com/typescript/announcing-typescript-7-0/#running-side-by-side-with-typescript-6.0 . The examples here retain TS5 because it is the currently declared supported peer, whereas TS6 widening remains proposed separately.

Checklist

• Unit tests updated — not applicable: documentation-only correction; the setup and compiler boundary were smoke-tested as described above.
• docs/ updated (if necessary)
• pnpm run update:examples run — not applicable: no generator output change.

Separate note: AI assistance

Prepared with Codex/Astra assistance. The recommendation was independently checked against the public AST API and the documented setup was executed locally before submission. A private-compiler runtime patch was deliberately not included because it could break existing custom transforms using a different compiler's AST.

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