Credential boundary

Skryba owns the credentials required to call detector APIs and RentAHuman. It does not hold direct model-provider keys: generation and quality judging go through Brama using a Brama client token.

Three credential domains

Domain	Variables	Used by
Detectors	GPTZERO_API_KEY, WINSTON_API_KEY, ORIGINALITY_API_KEY, SAPLING_API_KEY	score, rewrite, train
Brama	BRAMA_TOKEN; optional paired SKRYBA_AGENT_ID and SKRYBA_AGENT_AUTH_SECRET	rewrite, train, benchmark
RentAHuman	RENTAHUMAN_API_KEY	rentahuman create/get

score does not need Brama. benchmark does not call detectors. RentAHuman commands call neither Brama nor detectors.

Detector selection

Without --detectors, Skryba includes every detector whose key exists and is non-empty. With --detectors, the list is trimmed and lowercased, and each named provider's key must exist. This means environment changes can change the ensemble; pin names when scores must be comparable.

Exact refusals:

• no detector credentials found; configure GPTZERO_API_KEY, WINSTON_API_KEY, ORIGINALITY_API_KEY, or SAPLING_API_KEY
• <KEY_VARIABLE> is required for <detector>
• unknown detector "<name>"; available detectors: gptzero, originality, sapling, winston

Brama authentication

BRAMA_TOKEN is sent as a bearer token. The optional agent identity is all-or-nothing:

SKRYBA_AGENT_ID and SKRYBA_AGENT_AUTH_SECRET must be configured together

When both are present, src/brama.rs derives request authentication from the pair in addition to the bearer client token. Skryba never asks for Anthropic, OpenAI, or other model-provider keys.

RentAHuman authentication

The API key is sent in X-API-Key. A key containing control characters is refused with RENTAHUMAN_API_KEY contains invalid characters. Humanization ids are restricted to ASCII alphanumerics, _, and -, so caller input cannot rewrite the request path.

Desktop boundary

Skryba Desktop inherits its launch environment, then fills only missing variables from ~/.config/skryba/env. Existing environment values always win. The app passes that merged environment to one installed skryba process and does not parse, store, or transform credentials itself.