From 7d02e2a2f62752c5cf671539461a0598be81f9b7 Mon Sep 17 00:00:00 2001
From: KadenaFriend <241389759+kdafriend@users.noreply.github.com>
Date: Tue, 6 Jan 2026 15:15:14 +0000
Subject: [PATCH 1/8] Extend ForkHeight to manage by ForkNumber

---
 src/Chainweb/Chainweb/Configuration.hs   |  6 ++-
 src/Chainweb/Pact4/ModuleCache.hs        |  1 +
 src/Chainweb/Version.hs                  | 48 +++++++++++++++++++++---
 src/Chainweb/Version/Guards.hs           | 43 +++++++++++----------
 src/Chainweb/Version/Mainnet.hs          |  8 ++--
 src/Chainweb/Version/RecapDevelopment.hs |  2 +-
 src/Chainweb/Version/Testnet04.hs        |  6 +--
 src/Chainweb/Version/Utils.hs            |  2 +-
 test/lib/Chainweb/Test/TestVersions.hs   |  2 +-
 9 files changed, 82 insertions(+), 36 deletions(-)

diff --git a/src/Chainweb/Chainweb/Configuration.hs b/src/Chainweb/Chainweb/Configuration.hs
index 0f27adee78..2a65c6cc0e 100644
--- a/src/Chainweb/Chainweb/Configuration.hs
+++ b/src/Chainweb/Chainweb/Configuration.hs
@@ -605,10 +605,12 @@ parseVersion = constructVersion
             maybe (_versionUpgrades winningVersion) (\fub' ->
                 OnChains $ HM.mapWithKey
                     (\cid _ ->
-                        case winningVersion ^?! versionForks . at fub' . _Just . atChain cid of
+                        let currentUpgrades =  winningVersion ^?! versionUpgrades . atChain cid
+                        in case winningVersion ^?! versionForks . at fub' . _Just . atChain cid of
                             ForkNever -> error "Chainweb.Chainweb.Configuration.parseVersion: the fork upper bound never occurs in this version."
-                            ForkAtBlockHeight fubHeight -> HM.filterWithKey (\bh _ -> bh <= fubHeight) (winningVersion ^?! versionUpgrades . atChain cid)
+                            ForkAtBlockHeight fubHeight -> HM.filterWithKey (\bh _ -> bh <= fubHeight) currentUpgrades
                             ForkAtGenesis -> winningVersion ^?! versionUpgrades . atChain cid
+                            ForkAtForkNumber _ -> currentUpgrades -- For now, version upgrades were only allowed at blok heights
                     )
                     (HS.toMap (chainIds winningVersion))
             ) fub
diff --git a/src/Chainweb/Pact4/ModuleCache.hs b/src/Chainweb/Pact4/ModuleCache.hs
index ea961e8b80..e6e047c619 100644
--- a/src/Chainweb/Pact4/ModuleCache.hs
+++ b/src/Chainweb/Pact4/ModuleCache.hs
@@ -72,3 +72,4 @@ cleanModuleCache v cid bh =
         ForkAtBlockHeight bh' -> bh == bh'
         ForkAtGenesis -> bh == genesisHeight v cid
         ForkNever -> False
+        ForkAtForkNumber _ -> error "ChainWeb217Pact is not supposed to be indexed by a ForkNumber"
diff --git a/src/Chainweb/Version.hs b/src/Chainweb/Version.hs
index 222f26887a..7680e6f293 100644
--- a/src/Chainweb/Version.hs
+++ b/src/Chainweb/Version.hs
@@ -37,6 +37,7 @@ module Chainweb.Version
     -- * Properties of Chainweb Version
       Fork(..)
     , ForkHeight(..)
+    , succByHeight
     , _ForkAtBlockHeight
     , _ForkAtGenesis
     , _ForkNever
@@ -322,12 +323,49 @@ instance FromJSON Fork where
 instance FromJSONKey Fork where
     fromJSONKey = FromJSONKeyTextParser $ either fail return . eitherFromText
 
-data ForkHeight = ForkAtBlockHeight !BlockHeight | ForkAtGenesis | ForkNever
-    deriving stock (Generic, Eq, Ord, Show)
+data ForkHeight =  ForkAtForkNumber !ForkNumber | ForkAtBlockHeight !BlockHeight | ForkAtGenesis | ForkNever
+    deriving stock (Generic, Eq, Show)
     deriving anyclass (Hashable, NFData)
 
+instance Bounded ForkHeight where
+    minBound = ForkAtGenesis
+    maxBound = ForkNever
+
+instance Ord ForkHeight where
+    compare ForkAtGenesis ForkAtGenesis = EQ
+    compare ForkNever ForkNever = EQ
+    compare (ForkAtForkNumber a) (ForkAtForkNumber b) = compare a b
+    compare (ForkAtBlockHeight a)  (ForkAtBlockHeight b) = compare a b
+    compare ForkAtGenesis  _ = LT
+    compare _ ForkAtGenesis = GT
+    compare ForkNever _ = GT
+    compare _ ForkNever = LT
+    compare (ForkAtForkNumber fn) (ForkAtBlockHeight _)
+        | fn == 0 = LT
+        | otherwise = GT
+    compare (ForkAtBlockHeight _) (ForkAtForkNumber fn)
+        | fn == 0 = GT
+        | otherwise = LT
+
+-- We consider the following ordering for Forks:
+--   - ForkAtGenesis
+--   - ForkNumber = 0  (unusual case)
+--   - BlockHeihgt = 0 (unusual case)
+--   - Blockkheight = 1
+--          ..
+--   - BlockHeight = n
+--   - ForkNumber = 1
+--          ..
+--   - ForkNumber = n
+--   - ForkNever
+
 makePrisms ''ForkHeight
 
+succByHeight:: ForkHeight -> ForkHeight
+succByHeight (ForkAtBlockHeight x) = ForkAtBlockHeight $ succ x
+succByHeight ForkNever = ForkNever
+succByHeight _ = error "Only a Blockheight defined fork can be succ'ed"
+
 newtype ChainwebVersionName =
     ChainwebVersionName { getChainwebVersionName :: T.Text }
     deriving stock (Generic, Eq, Ord)
@@ -491,9 +529,9 @@ data ChainwebVersion
         --
         -- NOTE: This is internal. For the actual size of the serialized header
         -- use 'headerSizeBytes'.
-    , _versionMaxBlockGasLimit :: Rule BlockHeight (Maybe Natural)
+    , _versionMaxBlockGasLimit :: Rule ForkHeight (Maybe Natural)
         -- ^ The maximum gas limit for an entire block.
-    , _versionSpvProofRootValidWindow :: Rule BlockHeight (Maybe Word64)
+    , _versionSpvProofRootValidWindow :: Rule ForkHeight (Maybe Word64)
         -- ^ The minimum number of block headers a chainweb node should
         -- retain in its history at all times.
     , _versionBootstraps :: [PeerInfo]
@@ -504,7 +542,7 @@ data ChainwebVersion
         -- ^ Whether to disable any core functionality.
     , _versionDefaults :: VersionDefaults
         -- ^ Version-specific defaults that can be overridden elsewhere.
-    , _versionVerifierPluginNames :: ChainMap (Rule BlockHeight (Set VerifierName))
+    , _versionVerifierPluginNames :: ChainMap (Rule ForkHeight (Set VerifierName))
         -- ^ Verifier plugins that can be run to verify transaction contents.
     , _versionQuirks :: VersionQuirks
         -- ^ Modifications to behavior at particular blockheights
diff --git a/src/Chainweb/Version/Guards.hs b/src/Chainweb/Version/Guards.hs
index 90cbd94321..8e12df44cc 100644
--- a/src/Chainweb/Version/Guards.hs
+++ b/src/Chainweb/Version/Guards.hs
@@ -2,6 +2,9 @@
 {-# LANGUAGE ImportQualifiedPost #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
+-- TODO Remove this when checkFork' will be used for real
+{-# OPTIONS_GHC -Wno-unused-top-binds #-}
+
 -- |
 -- Module: Chainweb.Version.Guards
 -- Copyright: Copyright © 2023 Kadena LLC.
@@ -70,6 +73,7 @@ import Chainweb.BlockHeight
 import Chainweb.ChainId
 import Chainweb.Pact4.Transaction qualified as Pact4
 import Chainweb.Utils.Rule
+import Chainweb.ForkState
 import Chainweb.Version
 import Control.Lens
 import Data.Word (Word64)
@@ -86,32 +90,33 @@ import Pact.Types.Scheme (PPKScheme(ED25519, WebAuthn))
 getForkHeight :: Fork -> ChainwebVersion -> ChainId -> ForkHeight
 getForkHeight fork v cid = v ^?! versionForks . at fork . _Just . atChain cid
 
+-- Check Fork by height
 checkFork
-    :: (BlockHeight -> ForkHeight -> Bool)
+    :: (ForkHeight -> ForkHeight -> Bool)
     -> Fork -> ChainwebVersion -> ChainId -> BlockHeight -> Bool
-checkFork p f v cid h = p h (getForkHeight f v cid)
+checkFork p f v cid h = p (ForkAtBlockHeight h) (getForkHeight f v cid)
+
+-- CheckFork by forkNumber
+checkFork'
+    :: (ForkHeight -> ForkHeight -> Bool)
+    -> Fork -> ChainwebVersion -> ChainId -> ForkNumber -> Bool
+checkFork' p f v cid fn = p (ForkAtForkNumber fn) (getForkHeight f v cid)
+
 
-after :: BlockHeight -> ForkHeight -> Bool
-after bh (ForkAtBlockHeight bh') = bh > bh'
-after _ ForkAtGenesis = True
-after _ ForkNever = False
+after :: ForkHeight -> ForkHeight -> Bool
+after = (>)
 
-atOrAfter :: BlockHeight -> ForkHeight -> Bool
-atOrAfter bh (ForkAtBlockHeight bh') = bh >= bh'
-atOrAfter _ ForkAtGenesis = True
-atOrAfter _ ForkNever = False
+atOrAfter :: ForkHeight -> ForkHeight -> Bool
+atOrAfter = (>=)
 
-before :: BlockHeight -> ForkHeight -> Bool
-before bh (ForkAtBlockHeight bh') = bh < bh'
-before _ ForkAtGenesis = False
-before _ ForkNever = True
+before :: ForkHeight -> ForkHeight -> Bool
+before = (<)
 
 -- Intended for forks that intend to run upgrades at exactly one height, and so
 -- can't be "pre-activated" for genesis.
-atNotGenesis :: BlockHeight -> ForkHeight -> Bool
-atNotGenesis bh (ForkAtBlockHeight bh') = bh == bh'
+atNotGenesis :: ForkHeight -> ForkHeight -> Bool
 atNotGenesis _ ForkAtGenesis = error "fork cannot be at genesis"
-atNotGenesis _ ForkNever = False
+atNotGenesis fh fh' = fh == fh'
 
 -- -------------------------------------------------------------------------- --
 -- Header Validation Guards
@@ -332,11 +337,11 @@ pact4ParserVersion v cid bh
 
 maxBlockGasLimit :: ChainwebVersion -> BlockHeight -> Maybe Natural
 maxBlockGasLimit v bh = snd $ ruleZipperHere $ snd
-    $ ruleSeek (\h _ -> bh >= h) (_versionMaxBlockGasLimit v)
+    $ ruleSeek (\h _ -> ForkAtBlockHeight bh >= h) (_versionMaxBlockGasLimit v)
 
 minimumBlockHeaderHistory :: ChainwebVersion -> BlockHeight -> Maybe Word64
 minimumBlockHeaderHistory v bh = snd $ ruleZipperHere $ snd
-    $ ruleSeek (\h _ -> bh >= h) (_versionSpvProofRootValidWindow v)
+    $ ruleSeek (\h _ -> ForkAtBlockHeight bh >= h) (_versionSpvProofRootValidWindow v)
 
 -- | Different versions of Chainweb allow different PPKSchemes.
 --
diff --git a/src/Chainweb/Version/Mainnet.hs b/src/Chainweb/Version/Mainnet.hs
index 52e0960dbb..d7a460da7e 100644
--- a/src/Chainweb/Version/Mainnet.hs
+++ b/src/Chainweb/Version/Mainnet.hs
@@ -164,11 +164,11 @@ mainnet = ChainwebVersion
     , _versionWindow = WindowWidth 120
     , _versionHeaderBaseSizeBytes = 318 - 110
     , _versionMaxBlockGasLimit =
-        (succ $ mainnet ^?! versionForks . at Chainweb216Pact . _Just . atChain (unsafeChainId 0) . _ForkAtBlockHeight, Just 180_000) `Above`
+        (succByHeight $ mainnet ^?! versionForks . at Chainweb216Pact . _Just . atChain (unsafeChainId 0), Just 180_000) `Above`
         Bottom (minBound, Nothing)
     , _versionSpvProofRootValidWindow =
-        (succ $ mainnet ^?! versionForks . at Chainweb31 . _Just . atChain (unsafeChainId 0) . _ForkAtBlockHeight, Nothing) `Above`
-        (succ $ mainnet ^?! versionForks . at Chainweb231Pact . _Just . atChain (unsafeChainId 0) . _ForkAtBlockHeight, Just 20_000) `Above`
+        (succByHeight $ mainnet ^?! versionForks . at Chainweb31 . _Just . atChain (unsafeChainId 0), Nothing) `Above`
+        (succByHeight $ mainnet ^?! versionForks . at Chainweb231Pact . _Just . atChain (unsafeChainId 0) , Just 20_000) `Above`
         Bottom (minBound, Nothing)
     , _versionBootstraps = domainAddr2PeerInfo mainnetBootstrapHosts
     , _versionGenesis = VersionGenesis
@@ -223,7 +223,7 @@ mainnet = ChainwebVersion
         , _disableMempoolSync = False
         }
     , _versionVerifierPluginNames = AllChains $
-        (4_577_530, Set.fromList [VerifierName "hyperlane_v3_message"]) `Above`
+        (ForkAtBlockHeight $ BlockHeight 4_577_530, Set.fromList [VerifierName "hyperlane_v3_message"]) `Above`
         Bottom (minBound, mempty)
     , _versionQuirks = VersionQuirks
         { _quirkGasFees = onChains
diff --git a/src/Chainweb/Version/RecapDevelopment.hs b/src/Chainweb/Version/RecapDevelopment.hs
index 4e7fc17fb6..7936994326 100644
--- a/src/Chainweb/Version/RecapDevelopment.hs
+++ b/src/Chainweb/Version/RecapDevelopment.hs
@@ -124,7 +124,7 @@ recapDevnet = ChainwebVersion
         , _disableMempoolSync = False
         }
     , _versionVerifierPluginNames = AllChains $
-        (600, Set.fromList $ map VerifierName ["hyperlane_v3_message", "allow", "signed_list"]) `Above`
+        (ForkAtBlockHeight $ BlockHeight 600, Set.fromList $ map VerifierName ["hyperlane_v3_message", "allow", "signed_list"]) `Above`
         Bottom (minBound, mempty)
     , _versionQuirks = noQuirks
     , _versionForkNumber = 0
diff --git a/src/Chainweb/Version/Testnet04.hs b/src/Chainweb/Version/Testnet04.hs
index 7a4da9db56..ef5ffe7b59 100644
--- a/src/Chainweb/Version/Testnet04.hs
+++ b/src/Chainweb/Version/Testnet04.hs
@@ -144,10 +144,10 @@ testnet04 = ChainwebVersion
     , _versionWindow = WindowWidth 120
     , _versionHeaderBaseSizeBytes = 318 - 110
     , _versionMaxBlockGasLimit =
-        (succ $ testnet04 ^?! versionForks . at Chainweb216Pact . _Just . atChain (unsafeChainId 0) . _ForkAtBlockHeight, Just 180_000) `Above`
+        (succByHeight $ testnet04 ^?! versionForks . at Chainweb216Pact . _Just . atChain (unsafeChainId 0) , Just 180_000) `Above`
         Bottom (minBound, Nothing)
     , _versionSpvProofRootValidWindow =
-        (succ $ testnet04 ^?! versionForks . at Chainweb231Pact . _Just . atChain (unsafeChainId 0) . _ForkAtBlockHeight, Just 20_000) `Above`
+        (succByHeight $ testnet04 ^?! versionForks . at Chainweb231Pact . _Just . atChain (unsafeChainId 0) , Just 20_000) `Above`
         Bottom (minBound, Nothing)
     , _versionBootstraps = domainAddr2PeerInfo testnet04BootstrapHosts
     , _versionGenesis = VersionGenesis
@@ -190,7 +190,7 @@ testnet04 = ChainwebVersion
         { _disablePeerValidation = False
         , _disableMempoolSync = False
         }
-    , _versionVerifierPluginNames = AllChains $ (4_100_681, Set.fromList [VerifierName "hyperlane_v3_message"]) `Above`
+    , _versionVerifierPluginNames = AllChains $ (ForkAtBlockHeight $ BlockHeight $ 4_100_681, Set.fromList [VerifierName "hyperlane_v3_message"]) `Above`
         Bottom (minBound, mempty)
     , _versionQuirks = VersionQuirks
         { _quirkGasFees = onChains
diff --git a/src/Chainweb/Version/Utils.hs b/src/Chainweb/Version/Utils.hs
index b0cfb041ee..a7a32f781c 100644
--- a/src/Chainweb/Version/Utils.hs
+++ b/src/Chainweb/Version/Utils.hs
@@ -466,7 +466,7 @@ verifiersAt v cid bh =
         = snd
         $ ruleZipperHere
         $ snd
-        $ ruleSeek (\h _ -> bh >= h)
+        $ ruleSeek (\h _ -> ForkAtBlockHeight bh >= h)
         $ _versionVerifierPluginNames v ^?! atChain cid
 
 -- the mappings from names to verifier plugins is global. the list of verifier
diff --git a/test/lib/Chainweb/Test/TestVersions.hs b/test/lib/Chainweb/Test/TestVersions.hs
index b4a68d0ff4..f5afc26501 100644
--- a/test/lib/Chainweb/Test/TestVersions.hs
+++ b/test/lib/Chainweb/Test/TestVersions.hs
@@ -529,7 +529,7 @@ pact5InstantCpmTestVersionExpiryDisabled g = buildTestVersion $ \v -> v
             )
         )
     & versionSpvProofRootValidWindow .~
-        ( (BlockHeight 5, Nothing) `Above`
+        ( (ForkAtBlockHeight $ BlockHeight 5, Nothing) `Above`
             Bottom (minBound, Just 20)
         )
 

From 489728fb94663a241b75c6beea174797added013 Mon Sep 17 00:00:00 2001
From: kdafriend <241389759+kdafriend@users.noreply.github.com>
Date: Tue, 6 Jan 2026 18:43:06 +0100
Subject: [PATCH 2/8] Apply suggestions from code review

Co-authored-by: Edmund Noble <edmundnoble@users.noreply.github.com>
---
 src/Chainweb/Version.hs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/Chainweb/Version.hs b/src/Chainweb/Version.hs
index 7680e6f293..85d3375b9b 100644
--- a/src/Chainweb/Version.hs
+++ b/src/Chainweb/Version.hs
@@ -350,8 +350,8 @@ instance Ord ForkHeight where
 -- We consider the following ordering for Forks:
 --   - ForkAtGenesis
 --   - ForkNumber = 0  (unusual case)
---   - BlockHeihgt = 0 (unusual case)
---   - Blockkheight = 1
+--   - BlockHeight = 0 (unusual case)
+--   - BlockHeight = 1
 --          ..
 --   - BlockHeight = n
 --   - ForkNumber = 1
@@ -361,7 +361,7 @@ instance Ord ForkHeight where
 
 makePrisms ''ForkHeight
 
-succByHeight:: ForkHeight -> ForkHeight
+succByHeight :: ForkHeight -> ForkHeight
 succByHeight (ForkAtBlockHeight x) = ForkAtBlockHeight $ succ x
 succByHeight ForkNever = ForkNever
 succByHeight _ = error "Only a Blockheight defined fork can be succ'ed"

From 92fff2a0275c4db7e39eae3ec72a9464b4dba0da Mon Sep 17 00:00:00 2001
From: KadenaFriend <241389759+kdafriend@users.noreply.github.com>
Date: Tue, 6 Jan 2026 19:17:28 +0000
Subject: [PATCH 3/8] Add comments

---
 src/Chainweb/Version.hs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Chainweb/Version.hs b/src/Chainweb/Version.hs
index 85d3375b9b..0319d7610d 100644
--- a/src/Chainweb/Version.hs
+++ b/src/Chainweb/Version.hs
@@ -358,6 +358,11 @@ instance Ord ForkHeight where
 --          ..
 --   - ForkNumber = n
 --   - ForkNever
+--
+-- During the LLC era, forks were triggered by block heights, with a fork number of 0 (called feature flag).
+-- After version 3.1, forks are ONLY triggered by fork numbers, as soon as the fork number becomes equal to 1.
+-- So the fork heights are sorted chronologically: first block heights, then fork numbers.
+
 
 makePrisms ''ForkHeight
 

From dd5a906b2c13b7933fa742427ad60d8c869e9018 Mon Sep 17 00:00:00 2001
From: KadenaFriend <241389759+kdafriend@users.noreply.github.com>
Date: Wed, 7 Jan 2026 10:41:39 +0000
Subject: [PATCH 4/8] maxBlockGasLimit, minimumBlockHeaderHistory, verifiersAt
 use ForkNumber

---
 src/Chainweb/BlockHeaderDB/HeaderOracle.hs    |  6 +++---
 src/Chainweb/Chainweb.hs                      |  2 +-
 src/Chainweb/ForkState.hs                     |  6 ++++++
 .../Pact/PactService/Pact4/ExecBlock.hs       |  3 ++-
 .../Pact/PactService/Pact5/ExecBlock.hs       |  6 +++---
 src/Chainweb/Pact4/TransactionExec.hs         |  6 ++++--
 src/Chainweb/Pact5/TransactionExec.hs         |  2 +-
 src/Chainweb/Pact5/Types.hs                   |  5 +++++
 src/Chainweb/Version/Guards.hs                | 19 ++++++++++++-------
 src/Chainweb/Version/Utils.hs                 |  8 +++++---
 .../Chainweb/Test/Pact5/RemotePactTest.hs     |  2 +-
 11 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/src/Chainweb/BlockHeaderDB/HeaderOracle.hs b/src/Chainweb/BlockHeaderDB/HeaderOracle.hs
index 7b3ba75456..6a6d2eb4d1 100644
--- a/src/Chainweb/BlockHeaderDB/HeaderOracle.hs
+++ b/src/Chainweb/BlockHeaderDB/HeaderOracle.hs
@@ -29,14 +29,14 @@ module Chainweb.BlockHeaderDB.HeaderOracle
     where
 
 import Chainweb.BlockHash (BlockHash)
-import Chainweb.BlockHeader (BlockHeader, blockHash, blockHeight, genesisBlockHeader)
+import Chainweb.BlockHeader (BlockHeader, blockHash, blockHeight, blockForkNumber, genesisBlockHeader)
 import Chainweb.BlockHeaderDB (BlockHeaderDb)
 import Chainweb.TreeDB (seekAncestor)
 import Chainweb.TreeDB qualified as TreeDB
 import Chainweb.Version (_chainwebVersion)
 import Chainweb.Version.Guards (minimumBlockHeaderHistory)
 import Control.Exception (Exception(..), throwIO)
-import Control.Lens (view)
+import Control.Lens
 import Numeric.Natural (Natural)
 
 -- | A 'HeaderOracle' is a 'BlockHeaderDb' with a lower and upper bound, and the only
@@ -52,7 +52,7 @@ data HeaderOracle = HeaderOracle
 --   The lower bound of the oracle is determined by the 'spvProofExpirationWindow'.
 createSpv :: BlockHeaderDb -> BlockHeader -> IO HeaderOracle
 createSpv db upperBound = do
-    let mWindow = minimumBlockHeaderHistory (_chainwebVersion upperBound) (view blockHeight upperBound)
+    let mWindow = minimumBlockHeaderHistory (_chainwebVersion upperBound) (upperBound ^. blockForkNumber) (upperBound ^. blockHeight)
     let gh = genesisBlockHeader (_chainwebVersion upperBound) upperBound
     let defaultOracle = create db gh upperBound
 
diff --git a/src/Chainweb/Chainweb.hs b/src/Chainweb/Chainweb.hs
index e1ed1f0d54..28c6246db9 100644
--- a/src/Chainweb/Chainweb.hs
+++ b/src/Chainweb/Chainweb.hs
@@ -401,7 +401,7 @@ withChainwebInternal conf logger peer serviceSock rocksDb pactDbDir backupDir re
             (\cid x -> do
                 let mcfg = validatingMempoolConfig cid v (_configBlockGasLimit conf) (_configMinGasPrice conf)
                 -- NOTE: the gas limit may be set based on block height in future, so this approach may not be valid.
-                let maxGasLimit = fromIntegral <$> maxBlockGasLimit v maxBound
+                let maxGasLimit = fromIntegral <$> maxBlockGasLimit v maxBound maxBound
                 case maxGasLimit of
                     Just maxGasLimit'
                         | _configBlockGasLimit conf > maxGasLimit' ->
diff --git a/src/Chainweb/ForkState.hs b/src/Chainweb/ForkState.hs
index dc793d341a..97d2dcf34f 100644
--- a/src/Chainweb/ForkState.hs
+++ b/src/Chainweb/ForkState.hs
@@ -25,6 +25,7 @@ module Chainweb.ForkState
 -- * Fork Number
 , ForkNumber(..)
 , forkNumber
+, pact4ForkNumber
 
 -- * Fork Votes
 , ForkVotes(..)
@@ -132,6 +133,11 @@ forkNumber = lens _forkNumber $ \(ForkState w) v -> ForkState
     $ (w .&. 0xFFFFFFFF00000000)
     .|. (fromIntegral v .&. 0xFFFFFFFF)
 
+
+-- Pact4 -> Pact5 transition happened during ForkNumber=0 era.
+pact4ForkNumber:: ForkNumber
+pact4ForkNumber = 0
+
 -- ---------------------------------------------------------------------------
 -- Fork Votes
 
diff --git a/src/Chainweb/Pact/PactService/Pact4/ExecBlock.hs b/src/Chainweb/Pact/PactService/Pact4/ExecBlock.hs
index b7e92d4487..a0fb97a8c1 100644
--- a/src/Chainweb/Pact/PactService/Pact4/ExecBlock.hs
+++ b/src/Chainweb/Pact/PactService/Pact4/ExecBlock.hs
@@ -95,6 +95,7 @@ import Chainweb.Payload.PayloadStore
 import Chainweb.Time
 import Chainweb.Utils hiding (check)
 import Chainweb.Version
+import Chainweb.ForkState (pact4ForkNumber)
 import Chainweb.Version.Guards
 import Chainweb.Pact4.Backend.ChainwebPactDb
 import Data.Coerce
@@ -163,7 +164,7 @@ execBlock currHeader payload = do
     return (totalGasUsed, pwo)
   where
     blockGasLimit =
-      fromIntegral <$> maxBlockGasLimit v (view blockHeight currHeader)
+      fromIntegral <$> maxBlockGasLimit v pact4ForkNumber (view blockHeight currHeader)
 
     logInitCache = liftPactServiceM $ do
       mc <- fmap (fmap instr . _getModuleCache) <$> use psInitCache
diff --git a/src/Chainweb/Pact/PactService/Pact5/ExecBlock.hs b/src/Chainweb/Pact/PactService/Pact5/ExecBlock.hs
index 557ff53ac2..44f5bc2b50 100644
--- a/src/Chainweb/Pact/PactService/Pact5/ExecBlock.hs
+++ b/src/Chainweb/Pact/PactService/Pact5/ExecBlock.hs
@@ -577,7 +577,7 @@ execExistingBlock
   -> CheckablePayload
   -> PactBlockM logger tbl (P.Gas, PayloadWithOutputs)
 execExistingBlock currHeader payload = do
-  parentBlockHeader <- view psParentHeader
+  parentBlockHeader <- _parentHeader <$> view psParentHeader
   let plData = checkablePayloadToPayloadData payload
   miner :: Miner <- decodeStrictOrThrow (_minerData $ view payloadDataMiner plData)
   txs <- liftIO $ pact5TransactionsFromPayload plData
@@ -590,7 +590,7 @@ execExistingBlock currHeader payload = do
   isGenesis <- view psIsGenesis
   blockHandlePreCoinbase <- use pbBlockHandle
   let
-    txValidationTime = ParentCreationTime (view blockCreationTime $ _parentHeader parentBlockHeader)
+    txValidationTime = ParentCreationTime (parentBlockHeader ^. blockCreationTime)
   errors <- liftIO $ flip foldMap txs $ \tx -> do
     errorOrSuccess <- runExceptT $
       validateParsedChainwebTx logger v cid db blockHandlePreCoinbase txValidationTime
@@ -612,7 +612,7 @@ execExistingBlock currHeader payload = do
   postCoinbaseBlockHandle <- use pbBlockHandle
 
   let blockGasLimit =
-        Pact5.GasLimit . Pact5.Gas . fromIntegral <$> maxBlockGasLimit v (view blockHeight currHeader)
+        Pact5.GasLimit . Pact5.Gas . fromIntegral <$> maxBlockGasLimit v (parentBlockHeader ^. blockForkNumber) (currHeader ^. blockHeight)
 
   env <- ask
   (V.fromList -> results, (finalHandle, _finalBlockGasLimit)) <-
diff --git a/src/Chainweb/Pact4/TransactionExec.hs b/src/Chainweb/Pact4/TransactionExec.hs
index b877b1201b..7d324be85b 100644
--- a/src/Chainweb/Pact4/TransactionExec.hs
+++ b/src/Chainweb/Pact4/TransactionExec.hs
@@ -144,6 +144,7 @@ import qualified Pact.Utils.StableHashMap as SHM
 
 import Chainweb.BlockHeader
 import Chainweb.BlockHeight
+import Chainweb.ForkState (pact4ForkNumber)
 import Chainweb.Logger
 import qualified Chainweb.ChainId as Chainweb
 import Chainweb.Mempool.Mempool (pact4RequestKeyToTransactionHash)
@@ -371,7 +372,7 @@ applyCmd v logger gasLogger txFailuresCounter pdbenv miner gasModel txCtx txIdxI
     chainweb217Pact' = guardCtx chainweb217Pact txCtx
     chainweb219Pact' = guardCtx chainweb219Pact txCtx
     chainweb223Pact' = guardCtx chainweb223Pact txCtx
-    allVerifiers = verifiersAt v cid currHeight
+    allVerifiers = verifiersAt v cid pact4ForkNumber currHeight
     toEmptyPactError (PactError errty _ _ _) = PactError errty noInfo [] mempty
 
     toOldListErr pe = pe { peDoc = listErrMsg }
@@ -671,7 +672,8 @@ applyLocal logger gasLogger dbEnv gasModel txCtx spv cmdIn mc execConfig =
     currHeight = ctxCurrentBlockHeight txCtx
     cid = V._chainId txCtx
     v = _chainwebVersion txCtx
-    allVerifiers = verifiersAt v cid currHeight
+
+    allVerifiers = verifiersAt v cid pact4ForkNumber currHeight
     -- Note [Throw out verifier proofs eagerly]
     !verifiersWithNoProof =
         (fmap . fmap) (\_ -> ()) verifiers
diff --git a/src/Chainweb/Pact5/TransactionExec.hs b/src/Chainweb/Pact5/TransactionExec.hs
index a6e7fc8f0d..3be1e01d5b 100644
--- a/src/Chainweb/Pact5/TransactionExec.hs
+++ b/src/Chainweb/Pact5/TransactionExec.hs
@@ -183,7 +183,7 @@ runVerifiers txCtx cmd = do
       gasUsed <- liftIO . readIORef . _geGasRef . _txEnvGasEnv =<< ask
       let initGasRemaining = MilliGas $ case (gasToMilliGas (gasLimit ^. _GasLimit), gasUsed) of
             (MilliGas gasLimitMilliGasWord, MilliGas gasUsedMilliGasWord) -> gasLimitMilliGasWord - gasUsedMilliGasWord
-      let allVerifiers = verifiersAt v (_chainId txCtx) (ctxCurrentBlockHeight txCtx)
+      let allVerifiers = verifiersAt v (_chainId txCtx) (ctxParentForkNumber txCtx) (ctxCurrentBlockHeight txCtx)
       let toModuleName m =
             Pact4.ModuleName
                     { Pact4._mnName = _mnName m
diff --git a/src/Chainweb/Pact5/Types.hs b/src/Chainweb/Pact5/Types.hs
index 785be552e8..fa02097fa0 100644
--- a/src/Chainweb/Pact5/Types.hs
+++ b/src/Chainweb/Pact5/Types.hs
@@ -11,6 +11,7 @@ module Chainweb.Pact5.Types
     ( TxContext(..)
     , guardCtx
     , ctxCurrentBlockHeight
+    , ctxParentForkNumber
     , GasSupply(..)
     , PactBlockM(..)
     , PactBlockState(..)
@@ -34,6 +35,7 @@ import Chainweb.BlockHeader
 import Chainweb.Miner.Pact (Miner)
 import Chainweb.BlockHeight
 import Chainweb.Version
+import Chainweb.ForkState
 import Chainweb.Pact.Types
 import qualified Chainweb.ChainId
 import Control.Lens
@@ -84,6 +86,9 @@ ctxBlockHeader = _parentHeader . _tcParentHeader
 ctxCurrentBlockHeight :: TxContext -> BlockHeight
 ctxCurrentBlockHeight = succ . view blockHeight . ctxBlockHeader
 
+ctxParentForkNumber :: TxContext -> ForkNumber
+ctxParentForkNumber = view blockForkNumber . ctxBlockHeader
+
 ctxChainId :: TxContext -> Chainweb.ChainId.ChainId
 ctxChainId = _chainId . ctxBlockHeader
 
diff --git a/src/Chainweb/Version/Guards.hs b/src/Chainweb/Version/Guards.hs
index 8e12df44cc..3c1e631409 100644
--- a/src/Chainweb/Version/Guards.hs
+++ b/src/Chainweb/Version/Guards.hs
@@ -335,13 +335,18 @@ pact4ParserVersion v cid bh
     | chainweb213Pact v cid bh = Pact4.PactParserChainweb213
     | otherwise = Pact4.PactParserGenesis
 
-maxBlockGasLimit :: ChainwebVersion -> BlockHeight -> Maybe Natural
-maxBlockGasLimit v bh = snd $ ruleZipperHere $ snd
-    $ ruleSeek (\h _ -> ForkAtBlockHeight bh >= h) (_versionMaxBlockGasLimit v)
-
-minimumBlockHeaderHistory :: ChainwebVersion -> BlockHeight -> Maybe Word64
-minimumBlockHeaderHistory v bh = snd $ ruleZipperHere $ snd
-    $ ruleSeek (\h _ -> ForkAtBlockHeight bh >= h) (_versionSpvProofRootValidWindow v)
+maxBlockGasLimit :: ChainwebVersion -> ForkNumber -> BlockHeight -> Maybe Natural
+maxBlockGasLimit v fn bh = snd $ ruleZipperHere $ snd
+    $ ruleSeek (\h _ -> searchKey >= h) (_versionMaxBlockGasLimit v)
+    where
+        searchKey = ForkAtBlockHeight bh `max` ForkAtForkNumber fn
+
+
+minimumBlockHeaderHistory :: ChainwebVersion -> ForkNumber -> BlockHeight -> Maybe Word64
+minimumBlockHeaderHistory v fn bh = snd $ ruleZipperHere $ snd
+    $ ruleSeek (\h _ -> searchKey >= h) (_versionSpvProofRootValidWindow v)
+    where
+        searchKey = ForkAtBlockHeight bh `max` ForkAtForkNumber fn
 
 -- | Different versions of Chainweb allow different PPKSchemes.
 --
diff --git a/src/Chainweb/Version/Utils.hs b/src/Chainweb/Version/Utils.hs
index a7a32f781c..797003476d 100644
--- a/src/Chainweb/Version/Utils.hs
+++ b/src/Chainweb/Version/Utils.hs
@@ -64,6 +64,7 @@ import Chainweb.BlockHeight
 import Chainweb.ChainId
 import Chainweb.Difficulty
 import Chainweb.Time
+import Chainweb.ForkState
 import Chainweb.VerifierPlugin
 import qualified Chainweb.VerifierPlugin.Allow
 import qualified Chainweb.VerifierPlugin.Hyperlane.Announcement
@@ -458,16 +459,17 @@ expectedCutHeightAfterSeconds v s = eh * int (chainCountAt v (round eh))
     eh = expectedBlockHeightAfterSeconds v s
 
 -- | The verifier plugins enabled for a particular block.
-verifiersAt :: ChainwebVersion -> ChainId -> BlockHeight -> Map VerifierName VerifierPlugin
-verifiersAt v cid bh =
+verifiersAt :: ChainwebVersion -> ChainId -> ForkNumber -> BlockHeight -> Map VerifierName VerifierPlugin
+verifiersAt v cid fn bh =
     M.restrictKeys allVerifierPlugins activeVerifierNames
     where
     activeVerifierNames
         = snd
         $ ruleZipperHere
         $ snd
-        $ ruleSeek (\h _ -> ForkAtBlockHeight bh >= h)
+        $ ruleSeek (\h _ -> searchKey >= h)
         $ _versionVerifierPluginNames v ^?! atChain cid
+    searchKey = ForkAtBlockHeight bh `max` ForkAtForkNumber fn
 
 -- the mappings from names to verifier plugins is global. the list of verifier
 -- plugins active in any particular block validation context is the only thing
diff --git a/test/unit/Chainweb/Test/Pact5/RemotePactTest.hs b/test/unit/Chainweb/Test/Pact5/RemotePactTest.hs
index 2a85b549db..c6db34af54 100644
--- a/test/unit/Chainweb/Test/Pact5/RemotePactTest.hs
+++ b/test/unit/Chainweb/Test/Pact5/RemotePactTest.hs
@@ -397,7 +397,7 @@ spvExpirationTest v baseRdb prop = runResourceT $ do
         -- disabled" case, we definitely don't want to use maxBound.
         let expirationWindow = fromMaybe
                 (error "missing minimumBlockHeaderHistory")
-                (minimumBlockHeaderHistory v minBound)
+                (minimumBlockHeaderHistory v minBound minBound)
         when (int expirationWindow < waitBlocks + diameter (chainGraphAt v maxBound)) $ assertFailure "test version has a minimumBlockHeaderHistory that is too short to test"
 
         replicateM_ waitBlocks $ advanceAllChains_ fx

From 4e7fb56b48aa139184fe68f2b159c942f0339628 Mon Sep 17 00:00:00 2001
From: KadenaFriend <241389759+kdafriend@users.noreply.github.com>
Date: Wed, 7 Jan 2026 10:43:03 +0000
Subject: [PATCH 5/8] Headers compaction height depends on the ForkNumber  +
 Rename some variables

---
 src/Chainweb/Pact/Backend/Compaction.hs | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/Chainweb/Pact/Backend/Compaction.hs b/src/Chainweb/Pact/Backend/Compaction.hs
index 186b9b8536..83c1f5e43f 100644
--- a/src/Chainweb/Pact/Backend/Compaction.hs
+++ b/src/Chainweb/Pact/Backend/Compaction.hs
@@ -68,7 +68,7 @@ import "yet-another-logger" System.Logger hiding (Logger)
 import "yet-another-logger" System.Logger qualified as YAL
 import "yet-another-logger" System.Logger.Backend.ColorOption (useColor)
 import Chainweb.BlockHash
-import Chainweb.BlockHeader (blockHeight, blockHash, blockPayloadHash)
+import Chainweb.BlockHeader (blockHeight, blockForkNumber, blockHash, blockPayloadHash)
 import Chainweb.BlockHeaderDB.Internal (BlockHeaderDb(..), RankedBlockHeader(..))
 import Chainweb.BlockHeight (BlockHeight(..))
 import Chainweb.Cut.CutHashes (cutIdToText)
@@ -762,7 +762,7 @@ doCompactRocksDb logger cwVersion cids minBlockHeight srcDb targetDb = do
         iterLast it
         iterValue it >>= \case
           Nothing -> exitLog logger "Missing final payload. This is likely due to a corrupted database."
-          Just rbh -> pure (_getRankedBlockHeader rbh ^. blockHeight)
+          Just rbh -> pure $ _getRankedBlockHeader rbh
 
       -- The header that we start at depends on whether or not
       -- we have a minimal block header history window.
@@ -772,7 +772,10 @@ doCompactRocksDb logger cwVersion cids minBlockHeight srcDb targetDb = do
       --
       -- On new enough chainweb versions, we want to only copy over
       -- the minimal number of block headers.
-      case minimumBlockHeaderHistory cwVersion latestHeader of
+      -- Note, this behaviour may be dangerous in case of changes on the miniumum block history.
+      --
+      -- TODO = Option to prune headers history to the minimum should be enabled by flag.
+      case minimumBlockHeaderHistory cwVersion (latestHeader ^. blockForkNumber) (latestHeader ^. blockHeight) of
         -- Go to the earliest possible entry. We migrate all BlockHeaders, for now.
         -- They are needed for SPV.
         --
@@ -791,16 +794,18 @@ doCompactRocksDb logger cwVersion cids minBlockHeight srcDb targetDb = do
       earliestHeader <- do
         iterValue it >>= \case
           Nothing -> exitLog logger "Missing first payload. This is likely due to a corrupted database."
-          Just rbh -> pure (_getRankedBlockHeader rbh ^. blockHeight)
+          Just rbh -> pure $ _getRankedBlockHeader rbh
 
       -- Ensure that we log progress 100 times per chain
       -- I just made this number up as something that felt somewhat sensible
-      let offset = (latestHeader - earliestHeader) `div` 100
-      let headerProgressPoints = [earliestHeader + i * offset | i <- [1..100]]
+      let latestHeight = latestHeader ^. blockHeight
+          earliestHeight = earliestHeader ^. blockHeight
+          offset = (latestHeight - earliestHeight) `div` 100
+      let headerProgressPoints = [earliestHeight + i * offset | i <- [1..100]]
 
       let logHeaderProgress bHeight = do
             when (bHeight `elem` headerProgressPoints) $ do
-              let percentDone = sshow $ 100 * fromIntegral @_ @Double (bHeight - earliestHeader) / fromIntegral @_ @Double (latestHeader - earliestHeader)
+              let percentDone = sshow $ 100 * fromIntegral @_ @Double (bHeight - earliestHeight) / fromIntegral @_ @Double (latestHeight - earliestHeight)
               log' LL.Info $ percentDone <> "% done."
 
       let go = do

From e0f4b5f4c66bf863eb53945fcdeb8f2955e94a70 Mon Sep 17 00:00:00 2001
From: KadenaFriend <241389759+kdafriend@users.noreply.github.com>
Date: Wed, 7 Jan 2026 17:49:57 +0000
Subject: [PATCH 6/8] Validate that no fork or rules application happens by
 height after Chainweb31

---
 src/Chainweb/Version/RecapDevelopment.hs |  4 ++--
 src/Chainweb/Version/Registry.hs         | 26 +++++++++++++++++++++++-
 test/lib/Chainweb/Test/TestVersions.hs   |  5 +++--
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/src/Chainweb/Version/RecapDevelopment.hs b/src/Chainweb/Version/RecapDevelopment.hs
index 7936994326..a21a423cbb 100644
--- a/src/Chainweb/Version/RecapDevelopment.hs
+++ b/src/Chainweb/Version/RecapDevelopment.hs
@@ -78,8 +78,8 @@ recapDevnet = ChainwebVersion
         Chainweb228Pact -> AllChains $ ForkAtBlockHeight $ BlockHeight 650
         Chainweb230Pact -> AllChains $ ForkAtBlockHeight $ BlockHeight 680
         Chainweb231Pact -> AllChains $ ForkAtBlockHeight $ BlockHeight 690
-        Chainweb31 -> AllChains $ ForkAtBlockHeight $ BlockHeight 700
-        MigratePlatformShare -> AllChains $ ForkAtBlockHeight $ BlockHeight 710
+        MigratePlatformShare -> AllChains $ ForkAtBlockHeight $ BlockHeight 700
+        Chainweb31 -> AllChains $ ForkAtBlockHeight $ BlockHeight 710
 
     , _versionUpgrades = foldr (chainZip HM.union) (AllChains mempty)
         [ indexByForkHeights recapDevnet
diff --git a/src/Chainweb/Version/Registry.hs b/src/Chainweb/Version/Registry.hs
index f0653cdf37..aa7d3bfdfc 100644
--- a/src/Chainweb/Version/Registry.hs
+++ b/src/Chainweb/Version/Registry.hs
@@ -78,6 +78,24 @@ unregisterVersion v = do
     then error "You cannot unregister mainnet or testnet04 versions"
     else atomicModifyIORef' versionMap $ \m -> (HM.delete (_versionCode v) m, ())
 
+validateNoHeightAfterChainweb31' :: ChainwebVersion -> ForkHeight -> Either String ()
+validateNoHeightAfterChainweb31' v fh =
+    case (fork31Height, fh) of
+        (Just (ForkAtBlockHeight refAth), ForkAtBlockHeight ath) ->
+            if ath > (refAth + 1)
+                then Left ("validateVersion: Forking rule must only defined by Fork numbers after Chainweb31: " ++ show ath ++ " > " ++ show refAth)
+            else Right ()
+        _ -> Right ()
+    where
+        fork31Height =  v ^? versionForks . at Chainweb31 . _Just . atChain (unsafeChainId 0)
+
+validateNoHeightAfterChainweb31 :: ChainwebVersion -> Either String ()
+validateNoHeightAfterChainweb31 v =
+       (mapM_ (mapM_ (validateNoHeightAfterChainweb31' v)) (v ^. versionForks))
+    >> (mapM_ (validateNoHeightAfterChainweb31' v . fst) $ ruleElems $ v ^. versionMaxBlockGasLimit)
+    >> (mapM_ (validateNoHeightAfterChainweb31' v . fst) $ ruleElems $ v ^. versionSpvProofRootValidWindow)
+    >> (mapM_ (mapM_ (validateNoHeightAfterChainweb31' v . fst) . ruleElems) $ v ^. versionVerifierPluginNames)
+
 validateVersion :: HasCallStack => ChainwebVersion -> IO ()
 validateVersion v = do
     evaluate (rnf v)
@@ -92,8 +110,12 @@ validateVersion v = do
                 | not (all hasAllChains (_versionForks v)) ]
             , [ "validateVersion: chain graphs do not decrease in block height"
                 | not (ruleValid (_versionGraphs v)) ]
-            , [ "validateVersion: block gas limits do not decrease in block height"
+            , [ "validateVersion: block gas limits rules do not decrease in fork number and height"
                 | not (ruleValid (_versionMaxBlockGasLimit v)) ]
+            , [ "validateVersion: verifiers rules do not decrease in in fork number and height"
+                | not (all ruleValid (_versionVerifierPluginNames v)) ]
+             , [ "validateVersion: SPV valid window rules do not decrease in in fork number and height"
+                | not ( ruleValid (_versionSpvProofRootValidWindow v)) ]
             , [ "validateVersion: genesis data is missing for some chains"
                 | not (and
                     [ hasAllChains (_genesisBlockPayload $ _versionGenesis v)
@@ -102,6 +124,8 @@ validateVersion v = do
                     ])]
             , [ "validateVersion: some pact upgrade has no transactions"
                 | any (any isUpgradeEmpty) (_versionUpgrades v) ]
+            , [ err
+                | Left err <- [validateNoHeightAfterChainweb31 v] ]
             -- TODO: check that pact 4/5 upgrades are only enabled when pact 4/5 is enabled
             ]
     unless (null errors) $
diff --git a/test/lib/Chainweb/Test/TestVersions.hs b/test/lib/Chainweb/Test/TestVersions.hs
index f5afc26501..8f24d89ac9 100644
--- a/test/lib/Chainweb/Test/TestVersions.hs
+++ b/test/lib/Chainweb/Test/TestVersions.hs
@@ -330,8 +330,9 @@ slowForks = tabulateHashMap \case
     Chainweb228Pact -> AllChains $ ForkAtBlockHeight (BlockHeight 145)
     Chainweb230Pact -> AllChains $ ForkAtBlockHeight (BlockHeight 155)
     Chainweb231Pact -> AllChains $ ForkAtBlockHeight (BlockHeight 160)
-    Chainweb31 -> AllChains $ ForkAtBlockHeight (BlockHeight 165)
-    MigratePlatformShare -> AllChains $ ForkAtBlockHeight (BlockHeight 170)
+    MigratePlatformShare -> AllChains $ ForkAtBlockHeight (BlockHeight 165)
+    Chainweb31 -> AllChains $ ForkAtBlockHeight (BlockHeight 170)
+
 
 -- | A set of fork heights which are relatively fast, but not fast enough to break anything.
 fastForks :: HashMap Fork (ChainMap ForkHeight)

From e64444cd483cd129d121b16bb5560eea5a4689a1 Mon Sep 17 00:00:00 2001
From: kdafriend <241389759+kdafriend@users.noreply.github.com>
Date: Thu, 8 Jan 2026 09:35:33 +0100
Subject: [PATCH 7/8] Apply suggestions from code review

Co-authored-by: Edmund Noble <edmundnoble@users.noreply.github.com>
---
 src/Chainweb/Chainweb/Configuration.hs  | 2 +-
 src/Chainweb/ForkState.hs               | 2 +-
 src/Chainweb/Pact/Backend/Compaction.hs | 2 +-
 src/Chainweb/Pact5/Types.hs             | 5 +++++
 4 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/Chainweb/Chainweb/Configuration.hs b/src/Chainweb/Chainweb/Configuration.hs
index 2a65c6cc0e..fcbca2c303 100644
--- a/src/Chainweb/Chainweb/Configuration.hs
+++ b/src/Chainweb/Chainweb/Configuration.hs
@@ -610,7 +610,7 @@ parseVersion = constructVersion
                             ForkNever -> error "Chainweb.Chainweb.Configuration.parseVersion: the fork upper bound never occurs in this version."
                             ForkAtBlockHeight fubHeight -> HM.filterWithKey (\bh _ -> bh <= fubHeight) currentUpgrades
                             ForkAtGenesis -> winningVersion ^?! versionUpgrades . atChain cid
-                            ForkAtForkNumber _ -> currentUpgrades -- For now, version upgrades were only allowed at blok heights
+                            ForkAtForkNumber _ -> currentUpgrades -- For now, version upgrades were only allowed at block heights
                     )
                     (HS.toMap (chainIds winningVersion))
             ) fub
diff --git a/src/Chainweb/ForkState.hs b/src/Chainweb/ForkState.hs
index 97d2dcf34f..7b7b61a8b3 100644
--- a/src/Chainweb/ForkState.hs
+++ b/src/Chainweb/ForkState.hs
@@ -135,7 +135,7 @@ forkNumber = lens _forkNumber $ \(ForkState w) v -> ForkState
 
 
 -- Pact4 -> Pact5 transition happened during ForkNumber=0 era.
-pact4ForkNumber:: ForkNumber
+pact4ForkNumber :: ForkNumber
 pact4ForkNumber = 0
 
 -- ---------------------------------------------------------------------------
diff --git a/src/Chainweb/Pact/Backend/Compaction.hs b/src/Chainweb/Pact/Backend/Compaction.hs
index 83c1f5e43f..b0c1a9c116 100644
--- a/src/Chainweb/Pact/Backend/Compaction.hs
+++ b/src/Chainweb/Pact/Backend/Compaction.hs
@@ -772,7 +772,7 @@ doCompactRocksDb logger cwVersion cids minBlockHeight srcDb targetDb = do
       --
       -- On new enough chainweb versions, we want to only copy over
       -- the minimal number of block headers.
-      -- Note, this behaviour may be dangerous in case of changes on the miniumum block history.
+      -- Note, this behaviour may be dangerous in case of changes on the minimum block history.
       --
       -- TODO = Option to prune headers history to the minimum should be enabled by flag.
       case minimumBlockHeaderHistory cwVersion (latestHeader ^. blockForkNumber) (latestHeader ^. blockHeight) of
diff --git a/src/Chainweb/Pact5/Types.hs b/src/Chainweb/Pact5/Types.hs
index fa02097fa0..12e9aed687 100644
--- a/src/Chainweb/Pact5/Types.hs
+++ b/src/Chainweb/Pact5/Types.hs
@@ -86,6 +86,11 @@ ctxBlockHeader = _parentHeader . _tcParentHeader
 ctxCurrentBlockHeight :: TxContext -> BlockHeight
 ctxCurrentBlockHeight = succ . view blockHeight . ctxBlockHeader
 
+-- We use the parent fork number in Pact, so when the fork
+-- number is incremented, only that block's descendents will
+-- have the forking behavior active. We do this because computing
+-- the "currently active fork number" requires information from adjacent 
+-- headers, which is not actually available yet when we execute a new Pact payload.
 ctxParentForkNumber :: TxContext -> ForkNumber
 ctxParentForkNumber = view blockForkNumber . ctxBlockHeader
 

From 52c1a46c2cceb0d000e0c1631924a059b17201f8 Mon Sep 17 00:00:00 2001
From: KadenaFriend <241389759+kdafriend@users.noreply.github.com>
Date: Mon, 12 Jan 2026 19:55:16 +0000
Subject: [PATCH 8/8] Check that no fork use fork number of 0

---
 src/Chainweb/Version/Registry.hs | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/Chainweb/Version/Registry.hs b/src/Chainweb/Version/Registry.hs
index aa7d3bfdfc..5f5e1a5cb3 100644
--- a/src/Chainweb/Version/Registry.hs
+++ b/src/Chainweb/Version/Registry.hs
@@ -78,8 +78,8 @@ unregisterVersion v = do
     then error "You cannot unregister mainnet or testnet04 versions"
     else atomicModifyIORef' versionMap $ \m -> (HM.delete (_versionCode v) m, ())
 
-validateNoHeightAfterChainweb31' :: ChainwebVersion -> ForkHeight -> Either String ()
-validateNoHeightAfterChainweb31' v fh =
+validateNoHeightAfterChainweb31 :: ChainwebVersion -> ForkHeight -> Either String ()
+validateNoHeightAfterChainweb31 v fh =
     case (fork31Height, fh) of
         (Just (ForkAtBlockHeight refAth), ForkAtBlockHeight ath) ->
             if ath > (refAth + 1)
@@ -89,12 +89,21 @@ validateNoHeightAfterChainweb31' v fh =
     where
         fork31Height =  v ^? versionForks . at Chainweb31 . _Just . atChain (unsafeChainId 0)
 
-validateNoHeightAfterChainweb31 :: ChainwebVersion -> Either String ()
-validateNoHeightAfterChainweb31 v =
-       (mapM_ (mapM_ (validateNoHeightAfterChainweb31' v)) (v ^. versionForks))
-    >> (mapM_ (validateNoHeightAfterChainweb31' v . fst) $ ruleElems $ v ^. versionMaxBlockGasLimit)
-    >> (mapM_ (validateNoHeightAfterChainweb31' v . fst) $ ruleElems $ v ^. versionSpvProofRootValidWindow)
-    >> (mapM_ (mapM_ (validateNoHeightAfterChainweb31' v . fst) . ruleElems) $ v ^. versionVerifierPluginNames)
+validateNoForkAtZero :: ForkHeight -> Either String ()
+validateNoForkAtZero (ForkAtForkNumber atn)
+    | atn == 0 = Left ("ValidateSting: Fork Numbers can't be 0 ")
+    | otherwise = Right ()
+validateNoForkAtZero _ = Right ()
+
+
+validateForkHeights :: ChainwebVersion -> Either String ()
+validateForkHeights v =
+       (mapM_ (mapM_ doValidation) (v ^. versionForks))
+    >> (mapM_ (doValidation . fst) $ ruleElems $ v ^. versionMaxBlockGasLimit)
+    >> (mapM_ (doValidation . fst) $ ruleElems $ v ^. versionSpvProofRootValidWindow)
+    >> (mapM_ (mapM_ (doValidation . fst) . ruleElems) $ v ^. versionVerifierPluginNames)
+    where
+        doValidation fh = validateNoHeightAfterChainweb31 v fh >> validateNoForkAtZero fh
 
 validateVersion :: HasCallStack => ChainwebVersion -> IO ()
 validateVersion v = do
@@ -125,7 +134,7 @@ validateVersion v = do
             , [ "validateVersion: some pact upgrade has no transactions"
                 | any (any isUpgradeEmpty) (_versionUpgrades v) ]
             , [ err
-                | Left err <- [validateNoHeightAfterChainweb31 v] ]
+                | Left err <- [validateForkHeights v] ]
             -- TODO: check that pact 4/5 upgrades are only enabled when pact 4/5 is enabled
             ]
     unless (null errors) $