feat(ctb): Rename lastSigned to more accurate lastLive

This is more accurate because of the fact that showLiveness can be
used without approving a transaction.

packages/contracts-bedrock/src/Safe/LivenessGuard.sol

@@ -21,8 +21,8 @@ contract LivenessGuard is ISemver, GetSigners, BaseGuard {
     string public constant version = "1.0.0";
 
     Safe public immutable safe;
-    mapping(address => uint256) public lastSigned;
 
+    mapping(address => uint256) public lastLive;
     EnumerableSet.AddressSet private ownersBefore;
 
     constructor(Safe _safe) {
@@ -42,14 +42,14 @@ contract LivenessGuard is ISemver, GetSigners, BaseGuard {
             // If the value was present, remove() returns true.
             if (ownersBefore.remove(ownersAfter[i]) == false) {
                 // This address was not already an owner, add it to the lastSigned mapping
-                lastSigned[ownersAfter[i]] = block.timestamp;
+                lastLive[ownersAfter[i]] = block.timestamp;
             }
         }
         // Now iterate over the remaining ownersBefore entries. Any remaining addresses are no longer an owner, so we
         // delete them from the lastSigned mapping.
         for (uint256 j = 0; j < ownersBefore.length(); j++) {
             address owner = ownersBefore.at(j);
-            delete lastSigned[owner];
+            delete lastLive[owner];
         }
         return;
     }
@@ -104,7 +104,7 @@ contract LivenessGuard is ISemver, GetSigners, BaseGuard {
             _getNSigners({ dataHash: txHash, signatures: signatures, requiredSignatures: threshold });
 
         for (uint256 i = 0; i < signers.length; i++) {
-            lastSigned[signers[i]] = block.timestamp;
+            lastLive[signers[i]] = block.timestamp;
         }
         emit SignersRecorded(txHash, signers);
     }
@@ -113,7 +113,7 @@ contract LivenessGuard is ISemver, GetSigners, BaseGuard {
     ///         This is useful for owners who have not recently signed a transaction via the Safe.
     function showLiveness() external {
         require(safe.isOwner(msg.sender), "LivenessGuard: only Safe owners may demontstrate liveness");
-        lastSigned[msg.sender] = block.timestamp;
+        lastLive[msg.sender] = block.timestamp;
         address[] memory signers = new address[](1);
         signers[0] = msg.sender;
 

packages/contracts-bedrock/src/Safe/LivenessModule.sol

@@ -56,7 +56,7 @@ contract LivenessModule is ISemver {
     function removeOwner(address owner) external {
         // Check that the owner has not signed a transaction in the last 30 days
         require(
-            livenessGuard.lastSigned(owner) < block.timestamp - livenessInterval,
+            livenessGuard.lastLive(owner) < block.timestamp - livenessInterval,
             "LivenessModule: owner has signed recently"
         );
 

packages/contracts-bedrock/test/LivenessGuard.t.sol

@@ -51,7 +51,7 @@ contract LivnessGuard_CheckTx_Test is LivnessGuard_TestInit {
         safeInstance.execTransaction({ to: address(1111), value: 0, data: hex"abba" });
 
         for (uint256 i; i < safeInstance.threshold; i++) {
-            assertEq(livenessGuard.lastSigned(safeInstance.owners[i]), block.timestamp);
+            assertEq(livenessGuard.lastLive(safeInstance.owners[i]), block.timestamp);
         }
     }
 }
@@ -70,6 +70,6 @@ contract LivenessGuard_ShowLiveness_Test is LivnessGuard_TestInit {
         vm.prank(caller);
         livenessGuard.showLiveness();
 
-        assertEq(livenessGuard.lastSigned(caller), block.timestamp);
+        assertEq(livenessGuard.lastLive(caller), block.timestamp);
     }
 }

specs/safe-liveness-checking.md

@@ -32,7 +32,7 @@ This is achieved using two types of contracts which the Safe contract has built-
 
 For implementing liveness checks a `LivenessGuard` is created which receives the signatures from
 each executed transaction, and tracks the latest time at which a transaction was signed by each
-signer. This time is made publicly available by calling a `lastSigned(address)(Timestamp)` method.
+signer. This time is made publicly available by calling a `lastLive(address)(Timestamp)` method.
 
 Signers may also call the contract directly in order to prove liveness.
 
@@ -42,13 +42,12 @@ A `LivenessModule` is also created which does the following:
 
 1. Has a function `removeOwner()` that anyone may call to specify an owner to be removed from the
    Safe.
-1. The Module would then check the `LivenessGuard.lastSigned()` to determine if the signer is
+1. The Module would then check the `LivenessGuard.lastLive()` to determine if the signer is
    eligible for removal.
 1. If so, it will call the Safe's `removeSigner()` to remove the non-live signer, and if necessary
    reduce the threshold.
 1. When a member is removed, the signing parameters are modified such that `M/N` is the lowest ratio
-   which remains above 75%. These ratios are (9 of 12, 9 of 11, 8 of 10, 7 of 9, 6 of 8). Using
-   integer math, this can be expressed as `M = (N * 75 + 99) / 100`.
+   which remains above 75%. Using integer math, this can be expressed as `M = (N * 75 + 99) / 100`.
 
 ### Shutdown