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System One compatible decision providers

SchemaRouter can use any provider that is compatible with the typed System One decision contract through a single bounded backend.

This integration is model-neutral. Hosted Jev, self-hosted decision models, and future compatible runtimes can share the same SchemaRouter adapter when they expose the compatible System One client contract.

Install

pip install "schemarouter[systemone]"

The existing Jev-specific extra remains supported:

pip install "schemarouter[jev]"

Connect a compatible provider

from schemarouter.integrations import SystemOneDecisionBackend

backend = SystemOneDecisionBackend(
    base_url="http://127.0.0.1:8000/v1",
    model="kev-4b",
    provider_name="kev-local",
    min_confidence=0.70,
)

Pass the backend to the normal SchemaRouter decision surface. The model may choose only from the finite option IDs supplied by SchemaRouter.

Changing models should normally require only configuration changes:

backend = SystemOneDecisionBackend(
    base_url=SYSTEM_ONE_BASE_URL,
    model=SYSTEM_ONE_MODEL,
    provider_name=SYSTEM_ONE_PROVIDER,
)

No model-specific SchemaRouter class is required merely because the server changes.

What remains local

A compatible provider is a decision signal, not an execution authority.

SchemaRouter still:

  • constructs the finite candidate set from registered schema;
  • omits DecisionOption.metadata from provider-visible questions;
  • validates the returned option ID against the local candidate set;
  • rejects malformed, non-finite, or out-of-range confidence values;
  • applies the configured confidence abstention rule;
  • constructs and validates the execution plan locally;
  • retains policy, schema, fingerprint, and execution authority.

A provider cannot create a tool, endpoint, field, argument, or permission.

Direct Laya vs System One wire compatibility

LayaDecisionBackend remains useful when running the official Python Laya package directly, including its local checkpoint routing and CPU/CUDA/MPS controls.

Use SystemOneDecisionBackend instead when a Laya-compatible, Kev-compatible, or other System One model is served behind a compatible endpoint. This keeps deployment/runtime choice outside SchemaRouter's planning semantics.

Jev compatibility

JevDecisionBackend remains available and backward compatible. It is now the TypeSafe Jev specialization of the same generic provider contract, so existing applications do not need to migrate.

Evaluating new models

Wire compatibility does not imply quality equivalence. Before replacing a production decision model, evaluate the candidate on the same frozen workload and record:

  • exact-route accuracy;
  • unsupported and out-of-domain rejection;
  • false-route rate;
  • calibration/abstention behavior;
  • per-language and per-route behavior;
  • p50/p95 latency and model residency;
  • provider/runtime errors;
  • authority violations.

SchemaRouter's research harness uses this principle: infrastructure compatibility is reusable, while model promotion requires independent evidence.