docs: clarify validation slash model

CONTEXT.md

@@ -82,6 +82,14 @@ _Avoid_: mock contract, fake chain, temporary hack
 A trusted node (or the tracker itself) that re-runs a sample of inference requests to detect fraud.
 _Avoid_: auditor, checker, referee
 
+**Validation Event**:
+A completed inference record that contains enough information for a validator to decide whether to sample and re-run the request: session id, model preset, messages, inference route, node wallets, and observed output.
+_Avoid_: audit log, trace, receipt
+
+**Slash Proof**:
+The record submitted by a validator when a sampled re-run diverges from the observed output beyond tolerance. In the prototype this is deterministic local contract state; later it maps to an on-chain proof transaction.
+_Avoid_: accusation, report, claim
+
 ### Client-facing
 
 **Client**: