Generated types make an attachment's disposition required, though the spec gives it a default

[AminDhouib]

What happens

In sendly-sdk@1.0.0, dist/index.d.ts types an attachment's disposition as required:

attachments?: {
    filename: string
    content: string
    contentType?: string
    disposition: "attachment" | "inline"   // <- not optional
}[]

So this does not compile:

await sendly.emails.send({
    to: 'someone@example.com',
    from: 'us@example.com',
    subject: 'Report',
    body: '<p>Attached.</p>',
    attachments: [{ filename: 'report.pdf', content: base64 }],
})
// Property 'disposition' is missing in type '{ filename: string; content: string; }'

Why it is wrong

The OpenAPI schema declares default: "attachment" for that property, and it is not in the schema's required list. The API supplies the value; TypeScript should not force the caller to.

This is the usual openapi-typescript behaviour for a property carrying a default — the generator treats the default as a guarantee about the response shape and emits it as required on the request shape too. It is a generator artifact, not an intentional API constraint.

Suggested fix

The curated alias layer already solves exactly this elsewhere — PartialKeys<> is applied to CampaignV1Create.type and ListSubscribe.allowResubscribe. Extending it to the attachment item's disposition is a one-line change and needs no regeneration:

export type SendEmailV1Attachment = PartialKeys<
    NonNullable<components['schemas']['SendEmailV1']['attachments']>[number],
    'disposition'
>

It may be worth auditing the rest of the generated surface for other properties that carry a spec default and came out required for the same reason.

Context

Found while migrating a production app onto Sendly (transactional email, three services). Verified against the published sendly-sdk@1.0.0 tarball and https://api.sendly.now/api/openapi.json on 2026-09-03.