> ## Documentation Index
> Fetch the complete documentation index at: https://docs.infercrane.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Invariants

# System invariants

Changes that violate an invariant require maintainer review, an explicit migration and rollback
plan, and an update to this document in the same pull request.

## Data plane

* No PostgreSQL read occurs while routing an inference request.
* Authentication and aliases are resolved from immutable tenant-scoped in-memory snapshots.
* A published route is immutable; updates replace snapshots atomically.
* The gateway rewrites only the model alias and preserves streaming semantics.
* Server write timeouts remain disabled for long-lived inference streams.
* Retries are not duplicated between gateway and router.

## Control plane

* Desired state is durable; observed state can be reconstructed.
* A loopback router endpoint is consumed only by its owning gateway instance.
* Worker membership changes create a new router generation.
* Reconciliation work is bounded and cancellation-aware.
* Durable operation work has one unexpired lease owner and bounded attempts.
* Lifecycle core does not branch on provider or runtime names; composition binds versioned adapters.
* Adapter registration, hermetic qualification, real qualification, and public support are distinct.
* A supported integration capability cites executable evidence and cannot be inferred from protocol labels.
* Custom runtime revisions contain an immutable OCI digest and bounded argv; the control plane never
  builds an image or evaluates image-provided build/probe code.
* Recommendations and overflow decisions are versioned, persisted, reproducible, and fail closed on
  missing policy-required evidence; they never use an LLM or mutate a DeploymentSpec implicitly.

## Persistence

* PostgreSQL is the only production source of truth.
* Applied migrations are immutable and forward-only.
* Migration application is serialized and transactional.
* High-volume request records have indexed access paths and bounded retention.

## Security and operations

* Production secrets have no built-in defaults and do not enter logs or provider metadata.
* Credential secrets are never stored; only cryptographic hashes are persisted.
* External input sizes, concurrency, queues, timeouts and identifiers are bounded.
* Liveness does not depend on downstream systems; readiness verifies required dependencies.
* Development fakes are excluded from the production image target.
* Performance claims require reproducible tests against the exact real runtime, router and provider combination.