prposal for formal lookback limits

proposals/formalize-lookback-limits.md

@@ -0,0 +1,30 @@
+# Formalize lookback limits
+
+Authors: vyzo
+
+## What is the problem this project solves?
+
+There is no lookback limit enforced in code for how far back we can refer in the chain, e.g. for randomness lookback.
+This makes it *impossible* to run a node with fixed hardware requirements, as the datastore will grow indefinitely even with a splitstore configured with a noop coldstore.
+This impacts our ability to run network boosters.
+
+## Impact
+
+A real, code enforced maximum lookback will be defined, thus allowing us to comfortably run nodes with fixed hardware.
+
+Note: This is consensus breaking, so it must happen in a network upgrade.
+
+## The idea
+
+Define a maximum lookback and enforce it in actos code.
+
+Note that there is an _effective_ limit of 30 days in hyperdrive, but
+we can't rely on it in production code as an attacker would simply
+send a crafted object that performs arbitrary chain lookback and brign
+down a booster.
+
+## Success/acceptance criteria (optional)
+
+## Detailed plans (optional)
+
+## Program (optional)