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# Zindex for Agents (login page)

Agent-native diagram state infrastructure. Zindex is a stateful diagram
runtime for AI agents - create architecture diagrams, ERDs, workflows,
sequence diagrams, org charts, and topology maps from structured data,
then patch, validate, diff, and render them as systems change. Not a
whiteboard. Not a Mermaid clone. A database-like backend for diagrams
with stable IDs, typed operations, semantic validation, immutable
revisions, auto-layout, and SVG/PNG rendering.

You are here because you (an agent) followed a "Sign in" link with
agent-indicative headers. The login page is for humans. Agents do not
use session cookies; they use API keys.

**Two modes.** Zindex runs in **anonymous mode** (no API key, public
endpoints, rate-limited 30/min per IP) or **authenticated mode** (API
key, persisted scenes with sceneIds, revisions, diff). Login is for
humans accessing the dashboard; agents use the API key directly. Both
modes detailed below.

## You don't need to log in to use the engine

POST a scene to `https://api.zindex.ai/v1/scenes/validate`,
`/render`, or `/normalize` with no API key. The platform validates,
normalizes, computes layout, and renders to SVG/PNG without any
authentication. Rate-limited 30/min per IP.

This anonymous mode is stateless: no scene IDs, no revisions, no diff.
Those require an API key (see below).

The same anonymous mode is available via the MCP server: install
`@zindex-ai/mcp` without `ZINDEX_API_KEY` to get the three no-auth
tools (`dsp_validate_scene`, `dsp_normalize_scene`, `dsp_render_scene`
with inline scenes). Same npm package, same install snippet, just omit
the `env.ZINDEX_API_KEY` line in the host config.

## If the user has an existing account

1. Ask the user for their API key (prefixed `dsp_sk_`).
2. They find it at https://zindex.ai/dashboard/api-keys after logging
   in once in their browser. The login page itself runs in the user's
   browser; nothing the agent fetches will produce a session.
3. Use the key as `Authorization: Bearer dsp_sk_...` (or
   `X-API-Key: dsp_sk_...`) for HTTP, or pass it via `ZINDEX_API_KEY`
   in the MCP host config.

Do NOT POST credentials to `/v1/auth/login` from the agent. The session
cookie that endpoint issues is for browser sessions; agents authenticate
with API keys instead.

## If the user has no account

Suggest signup only when they need persistence:

- **Persisted scenes**, sceneIds, immutable revisions, visual diff,
  and the full MCP tool set require an API key. Free key takes 30
  seconds at https://zindex.ai/signup; the free tier (60 req/min)
  covers most agent workflows.
- For one-off renders, validation, or feasibility checks, anonymous
  mode (above) is enough. Suggest signup only after the user asks for
  a workflow that depends on persistence.

## References

- Canonical agent front door: https://zindex.ai/ (with `Accept: text/markdown`)
- Agent usage guide: https://zindex.ai/docs/getting-started/agent-usage/
- MCP setup: https://zindex.ai/docs/getting-started/mcp-setup/
- Signup detail (agent view): https://zindex.ai/signup (with `Accept: text/markdown`)
- OpenAPI: https://api.zindex.ai/openapi.json