---
title: "Begin a server-orchestrated external SSO login (Zitadel idpIntent)"
method: GET
path: "/auth/idp/start"
tags: ["Auth"]
---

# Begin a server-orchestrated external SSO login (Zitadel idpIntent)

`GET /auth/idp/start`

## Request

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

MNE-1449 re-flip. Server-drives the external-IdP (Microsoft Entra) login via Zitadel's idpIntent CORE API so the Zitadel hosted-login UI never renders. Starts a `POST /v2/idp_intents`, sets a short-lived `mnemom_idp_initiator` cookie (HMAC-signed state carrying the allowlisted `redirect_after` — the CSRF binding), and 302-redirects the browser to the external IdP authorize URL. DARK: returns 503 unless the cell is configured with `AUTH_PROVIDER=zitadel` + `ZITADEL_DEFAULT_IDP_ID`.

## Query parameters

- `redirect_after` string

## Other responses

- `302`: Redirects to the external IdP authorize endpoint. Sets `mnemom_idp_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.
- `502`: An upstream dependency returned an invalid response.
- `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)