SIGNAL is versioned by default. Past states remain inspectable so users can see not only what is believed, but how understanding evolved over time.
Material changes create new versions with explicit lineage (supersedes / deprecated-by).
Prior versions remain accessible for auditability, critique, and learning.
The system is designed to reconstruct what SIGNAL showed at a specific historical date — using the data, methods, and assumptions available then.
This prevents retroactive revisionism while enabling serious ex post analysis.
Observations preserve when a measurement applies; derived views preserve when they were computed.
This supports honest replay of past understandings without collapsing projections into facts.
