# Signals

## Purpose
Reachability scoring, unknowns registry, and signal APIs.

## Inputs
- Call graphs and runtime facts

## Outputs
- Reachability facts and unknowns records

## Data and storage
- PostgreSQL and artifact store

## Key dependencies
- Scanner and Zastava

## Notes and boundaries
- Deterministic scoring with unknowns pressure

## Related docs
- docs/modules/signals/evidence/README.md
- docs/modules/signals/unknowns/2025-12-01-unknowns-registry.md