feat: automatically clear unsupplied blacklisted tokens (backport #1808)

CHANGELOG.md

@@ -46,6 +46,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+### Features
+
+- [1808](https://github.com/umee-network/umee/pull/1808) Blacklisted tokens automatically cleared from token registry if they have not yet been supplied.
+
 ### Fixes
 
 - [1812](https://github.com/umee-network/umee/pull/1812) MaxCollateralShare now works during partial oracle outages when certain conditions are safe.

x/leverage/README.md

@@ -298,6 +298,12 @@ See [leverage tx proto](https://github.com/umee-network/umee/blob/main/proto/ume
 
 `Update-Registry` gov proposal will adds the new tokens to token registry or update the existing token with new settings.
 
+Under certain conditions, tokens will be automatically deleted:
+- The token has been blacklisted by a previous proposal or the current one
+- The token has not been supplied to the module, so there are no uTokens, borrows, or collateral associated with it.
+
+The conditions allow for mistakenly registered tokens which have never been used to be removed from the registry. It is not safe to remove a token with active supply or borrows, so those stay listed in the registry when blacklisted.
+
 ### CLI
 ```bash
 umeed tx gov submit-proposal [path-to-proposal-json] [flags]

x/leverage/keeper/msg_server.go

@@ -470,5 +470,11 @@ func (s msgServer) GovUpdateRegistry(
 		return &types.MsgGovUpdateRegistryResponse{}, err
 	}
 
+	// cleans blacklisted tokens from the registry if they have not been supplied
+	err = s.keeper.CleanTokenRegistry(ctx)
+	if err != nil {
+		return &types.MsgGovUpdateRegistryResponse{}, err
+	}
+
 	return &types.MsgGovUpdateRegistryResponse{}, nil
 }

x/leverage/keeper/token.go

@@ -5,6 +5,36 @@ import (
 	"github.com/umee-network/umee/v4/x/leverage/types"
 )
 
+// CleanTokenRegistry deletes all blacklisted tokens in the leverage registry
+// whose uToken supplies are zero. Called automatically on registry update.
+func (k Keeper) CleanTokenRegistry(ctx sdk.Context) error {
+	tokens := k.GetAllRegisteredTokens(ctx)
+	for _, t := range tokens {
+		if t.Blacklist {
+			uDenom := types.ToUTokenDenom(t.BaseDenom)
+			uSupply := k.GetUTokenSupply(ctx, uDenom)
+			if uSupply.IsZero() {
+				err := k.deleteTokenSettings(ctx, t)
+				if err != nil {
+					return err
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// deleteTokenSettings deletes a Token in the x/leverage module's KVStore.
+// it should only be called by CleanTokenRegistry.
+func (k Keeper) deleteTokenSettings(ctx sdk.Context, token types.Token) error {
+	store := ctx.KVStore(k.storeKey)
+	tokenKey := types.KeyRegisteredToken(token.BaseDenom)
+	store.Delete(tokenKey)
+	// call oracle hooks on deleted (not just blacklisted) token
+	k.hooks.AfterRegisteredTokenRemoved(ctx, token)
+	return nil
+}
+
 // SetTokenSettings stores a Token into the x/leverage module's KVStore.
 func (k Keeper) SetTokenSettings(ctx sdk.Context, token types.Token) error {
 	if err := token.Validate(); err != nil {