API reference

SDK

@idem0/sdk is two pure functions — a config producer, not a client wrapper.

Spread the result into your provider SDK constructor, once per client.

Option	Type	Required	Description
`idem0Key`	`string`	yes	Your idem0 key. Sent as `x-idem0-key`. Not your provider token.
`provider`	`"anthropic" \| "openai"`	yes	Which upstream to route to.
`endpoint`	`string`	no	Proxy base URL. Defaults to `https://api.idem0.dev`. Set only when self-hosting.

Returns:

{
  baseURL: string;                          // <endpoint>/anthropic or <endpoint>/openai/v1
  defaultHeaders: { "x-idem0-key": string };
}

Build the per-call header. Drop it into a request’s headers.

idempotencyKey("job-42"); // → { "Idempotency-Key": "job-42" }

The key is caller-owned and passed through verbatim — idem0 never generates it.

No SDK required — any HTTP client works. Point your requests at the idem0 proxy and add two headers.

Provider	Base URL	Example path
Anthropic	`https://api.idem0.dev/anthropic`	`/anthropic/v1/messages`
OpenAI	`https://api.idem0.dev/openai/v1`	`/openai/v1/chat/completions`

The proxy strips the provider prefix and forwards everything else upstream unchanged.

Header	Description
`x-idem0-key`	Your idem0 key.
`Idempotency-Key`	Stable key for this unit of work. Same key → replay.
provider auth	Your normal provider auth, untouched: `x-api-key` (Anthropic) or `Authorization: Bearer` (OpenAI).

Header	Description
`idem0-idempotent-replayed`	`true` when the response was replayed from cache (0 credits). Absent on a fresh call.

Status	Meaning
`200`	Success — a fresh call, or a replay (check `idem0-idempotent-replayed`).
`409 Conflict`	The same key is already in flight. Retry after the first call finishes.
`422 Unprocessable`	The same key was reused with a different request body. Use a new key, or the original body.

Keyless requests pass straight through to the provider — no idempotency, no change in behavior.