Authentication

All authenticated endpoints accept a single Bearer token, configured server-side as RUST_API_BEARER in .env. The token is opaque (random 32-byte hex by convention) and compared constant-time to defeat timing attacks.

Authorization: Bearer <token>

Send it on every request to:

/v1/chat/completions
/v1/models
/v1/info
/v1/embeddings
/v1/images*
/v1/audio/transcriptions, /v1/audio/translations
/v1/tools/execute
/v1/memory*, /v1/system-prompts*
/v1/tenant/config* (Cut 2.13 — needs tenant_config:read|write scope)
/c1/chat
/c1/conversations*
/a1/agents*, /a1/rag/indices*

These endpoints are public (no Bearer required):

/
/healthz
/readyz
/openapi, /openapi.json, /redoc
/docs/*
/errors
/playground

Errors

Code	Status	When
`missing_authorization`	401	No `Authorization` header
`invalid_authorization`	401	Bearer doesn't match server config
`rate_limit_exceeded`	429	Too many requests for this token (see below)

# Without auth — gets 401:
curl -i https://dgx.spass.fun/v1/info

# With auth — 200 OK:
curl -s -H "Authorization: Bearer $BEARER" https://dgx.spass.fun/v1/info \
  | jq '.models[0].alias'

Rate limits

Per-token rate limits are enforced via tower_governor:

Default: 1 request/second, burst of 30.
Bucket key: SHA-256 hash of the bearer token — not the IP. Distinct tokens get distinct buckets even from the same IP; the same token shares one bucket across all IPs.
Tunable server-side: RATE_LIMIT_PER_SECOND, RATE_LIMIT_BURST env vars.

When you exceed the limit you get HTTP 429 with the standard error envelope:

{
  "error": {
    "type": "rate_limit_exceeded",
    "code": "rate_limit_exceeded",
    "message": "Rate limit exceeded"
  }
}

End-User Identity (Header-only, ADR 0016 / Cut 2.23c)

SPASS-User-Id is the sole authority for end-user identity across all user-scoped endpoints (/c1/*, /v1/chat/completions, /v1/memory/*, /v1/system-prompts/*, /a1/agents/*/sessions/*).

Mandatory — endpoints reject requests without it with HTTP 400 missing_field, param: headers.spass-user-id. Exception: tokens with role tenant_admin may omit the header for read-only endpoints to get a tenant-wide view (no user-id filter).

Body and query user_id are forbidden — sending either returns HTTP 400 invalid_field with param: body.user_id or query.user_id.

POST /c1/chat
Authorization: Bearer <token>
SPASS-User-Id: alice
Content-Type: application/json

{
  "model": "llama-4-scout",
  "conversation_id": "<id-owned-by-alice>",
  "message": "...",
  "stream": false
}

Requesting a conversation_id that belongs to a different end-user returns HTTP 404 conversation_not_found (avoids existence-leak).

Agent sessions are user-scoped — /a1/agents/{name}/sessions/* filter strictly on SPASS-User-Id. A user only sees their own sessions, even when the bearer is shared across multiple end-users.

For the migration history (Cut 2.19 → ADR 0014 → ADR 0016 strict-mode sweep), see docs/adr/0016-user-identity-authority-header-only.md.

Token rotation

Rotating the bearer is server-side only:

NEW=$(openssl rand -hex 32)
sed -i "s/^RUST_API_BEARER=.*/RUST_API_BEARER=$NEW/" /home/dietmar/dgx-llm/.env
docker compose restart rust-api

There's no on-the-fly token refresh — clients must be updated externally with the new value. For production deployments where multiple clients share a key, consider scripting this into your secrets pipeline.

Body size limit

Bodies larger than MAX_BODY_BYTES (default 32 MB) get HTTP 413 with code: body_too_large. Triggered most often by very large base64-encoded image inputs; resize the image or split the conversation.