---
title: "Begin an OIDC authorization-code login (Zitadel redirect leg)"
method: GET
path: "/auth/oidc/start"
tags: ["Auth"]
---

# Begin an OIDC authorization-code login (Zitadel redirect leg)

`GET /auth/oidc/start`

## Request

- Base URL: `https://api.mnemom.ai/v1`
- URL: `https://api.mnemom.ai/v1/auth/oidc/start`
- Auth: none required

B1 PR-B (MNE-1449). Generates PKCE + an HMAC-signed state + single-use nonce, sets a short-lived `mnemom_oidc_initiator` cookie, and 302-redirects the browser to the Zitadel hosted-login authorize endpoint. Plumbing for hosted-login / enterprise SSO (PR-E). Returns 503 unless the cell is configured with `AUTH_PROVIDER=zitadel` + the login-client config.

## Query parameters

- `redirect_after` string

## Other responses

- `302`: Redirects to the Zitadel authorize endpoint. Sets `mnemom_oidc_initiator` cookie.
- `429`: Rate-limit exceeded. The global per-IP limiter (100 requests/minute, applied to every `/v1/*` route) rejected this request. Back off until the window resets — `Retry-After` carries the cooldown in seconds and `X-RateLimit-Reset` the absolute reset time.
- `500`: Server error — request was well-formed but the server failed to fulfill it. Typically a downstream dependency (DB / RPC / external API) returned an unexpected error.
- `503`: An upstream dependency is currently unavailable. The request was not processed; retry after the cooldown window.

---

[API](https://skmtc.dev/mnemom/apis/mnemom-api.md) · [All operations](https://skmtc.dev/mnemom/apis/mnemom-api/llms.txt) · [OpenAPI document](https://skmtc.dev/mnemom/apis/mnemom-api/revisions/274b7a6ea182?raw)