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

# Observe (Shadow) Mode

> Enforce, observe, or skip runtime behavior with built-in decision sinks.

## Embedded Runtime Modes (Enforce / Observe / Skip)

Use `evaluate_execute_controlled(...)` for staged rollout before strict enforcement.

Modes:

* `enforce`: block writes on denied decision
* `observe`: allow writes but emit denied decision evidence
* `skip`: bypass decision evaluation and optionally emit skipped events

## Example (FastAPI-style flow)

```python theme={null}
from kernite import ObservabilityConfig, evaluate_execute_controlled

config = ObservabilityConfig.from_env()
sink = config.create_sink()

result = evaluate_execute_controlled(
    request_body,
    idempotency_key="req-001",
    mode=config.mode,
    sink=sink,
    sink_failure_policy=config.sink_failure_policy,
)

if not result["allow_write"]:
    return {"ok": False, "governance": result["governance"]}

# proceed with mutation
```

## Environment Controls

* `KERNITE_MODE=enforce|observe|skip` (default `enforce`)
* `KERNITE_SINK=none|jsonl|csv|sqlite` (default `none`)
* `KERNITE_SINK_PATH=/absolute/path` (required when sink enabled)
* `KERNITE_SINK_FAIL_POLICY=fail_open|fail_closed` (default `fail_open`)

## Sink Behavior

Built-in sinks:

* `JsonlDecisionSink`
* `CsvDecisionSink`
* `SqliteDecisionSink`

Emitted event schema: `kernite.decision_event.v1`.