add spec on vesting, proposals

docs/tech-design/vesting.md

@@ -0,0 +1,37 @@
+# Vesting contract technical design
+
+| Spec Status | Impl Status | Last Revision |
+|-------------|-------------|---------------|
+| WIP         |  WIP        | 2022-01-18    |
+
+--------------------
+
+**Spec Ownership:** [@Emily Martins]
+
+**Authors**: [@Emily Martins]
+
+**Impl Owner:** [@Emily Martins]
+
+[@Emily Martins]: https://github.com/emiflake
+
+--------------------
+
+## Vesting contract
+
+In order to distribute governance tokens, one or more vesting contracts may be deployed.
+
+First and foremost, there is a _schedule_ for the distribution of said tokens. Alongside this schedule, we keep track of how much we've distributed so far. This allows us to calculate how much is "due" at any particular time.
+
+To gain intuition, you can think of it being implemented this way:
+
+```haskell
+distributed :: Schedule -> Time -> Value
+distributed schedule time = scanl (+) mempty schedule !! time
+
+due :: Schedule -> Value -> Time -> Value
+due schedule alreadyDistributed time = distributed schedule time - alreadyDistributed
+```
+
+The vesting contract may require that only an address in a particular set can withdraw from it.
+
+The vesting contract may have an optional escape hatch for trusted authority to recover from a potential DAO operation.