diff --git a/agora-specs/Property/Governor.hs b/agora-specs/Property/Governor.hs
index 7925e80..5bd5097 100644
--- a/agora-specs/Property/Governor.hs
+++ b/agora-specs/Property/Governor.hs
@@ -30,6 +30,7 @@ import Plutarch.Context (
   output,
   script,
   withDatum,
+  withMinting,
   withOutRef,
   withValue,
  )
@@ -43,6 +44,7 @@ import PlutusLedgerApi.V1.Value (assetClassValue)
 import Property.Generator (genInput, genOutput)
 import Sample.Shared (
   govAssetClass,
+  govSymbol,
   govValidatorHash,
   governor,
   gstUTXORef,
@@ -181,7 +183,7 @@ governorMintingProperty =
               GovernorOutputNotFound -> referencedInput <> mintAmount 1
               GovernorPolicyCorrect -> referencedInput <> outputToGov <> mintAmount 1
 
-      return . buildMintingUnsafe $ inputs <> outputs <> comp
+      return . buildMintingUnsafe $ inputs <> outputs <> comp <> withMinting govSymbol
 
     expected :: ScriptContext -> Maybe ()
     expected sc =
diff --git a/agora-specs/Sample/Governor/Initialize.hs b/agora-specs/Sample/Governor/Initialize.hs
index db7f1d7..4bdc0e3 100644
--- a/agora-specs/Sample/Governor/Initialize.hs
+++ b/agora-specs/Sample/Governor/Initialize.hs
@@ -30,8 +30,6 @@ import Agora.Proposal.Time (MaxTimeRangeWidth (MaxTimeRangeWidth), ProposalTimin
 import Data.Default (Default (..))
 import Plutarch.Api.V1 (mintingPolicySymbol, mkMintingPolicy)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   mint,
   output,
@@ -46,9 +44,6 @@ import Plutarch.Context (
 import PlutusLedgerApi.V1 (
   CurrencySymbol,
   MintingPolicy,
-  ScriptContext (..),
-  ScriptPurpose (Minting),
-  TxInfo,
   TxOutRef (TxOutRef),
   ValidatorHash,
  )
@@ -59,7 +54,7 @@ import Sample.Shared (
  )
 import Sample.Shared qualified as Shared
 import Test.Specification (SpecificationTree, testPolicy)
-import Test.Util (pubKeyHashes, sortValue)
+import Test.Util (CombinableBuilder, mkMinting, pubKeyHashes, sortValue)
 
 data Parameters = Parameters
   { datumThresholdsValid :: Bool
@@ -115,8 +110,8 @@ govSymbol = mintingPolicySymbol govPolicy
 
 --------------------------------------------------------------------------------
 
-mintGST :: Parameters -> TxInfo
-mintGST ps = buildTxInfoUnsafe builder
+mintGST :: forall b. CombinableBuilder b => Parameters -> b
+mintGST ps = builder
   where
     gstAC =
       if ps.mintStateTokenWithName
@@ -149,7 +144,6 @@ mintGST ps = buildTxInfoUnsafe builder
 
     ---
 
-    witnessBuilder :: BaseBuilder
     witnessBuilder =
       if ps.presentWitness
         then
@@ -166,7 +160,6 @@ mintGST ps = buildTxInfoUnsafe builder
 
     ---
 
-    govBuilder :: BaseBuilder
     govBuilder =
       let datum =
             if ps.withGovernorDatum
@@ -177,8 +170,6 @@ mintGST ps = buildTxInfoUnsafe builder
               . withValue governorValue
               . datum
     --
-
-    builder :: BaseBuilder
     builder =
       mconcat
         [ txId "986b756ffb1c9839fc8d0b22a308ac91d5b5d0ebbfa683a47588c8a5cf70b5af"
@@ -247,17 +238,10 @@ mintGSTWithNoneEmptyNameParameters =
 --------------------------------------------------------------------------------
 
 mkTestCase :: String -> Parameters -> Bool -> SpecificationTree
-mkTestCase
-  name
-  ps
-  valid = policyTest
-    where
-      txInfo = mintGST ps
-
-      policyTest =
-        testPolicy
-          valid
-          name
-          (governorPolicy governor)
-          ()
-          (ScriptContext txInfo (Minting govSymbol))
+mkTestCase name ps valid =
+  testPolicy
+    valid
+    name
+    (governorPolicy governor)
+    ()
+    (mkMinting mintGST ps govSymbol)
diff --git a/agora-specs/Sample/Governor/Mutate.hs b/agora-specs/Sample/Governor/Mutate.hs
index 8b789b0..fa818e4 100644
--- a/agora-specs/Sample/Governor/Mutate.hs
+++ b/agora-specs/Sample/Governor/Mutate.hs
@@ -24,8 +24,6 @@ import Agora.Utils (validatorHashToTokenName)
 import Data.Default (def)
 import Plutarch.Api.V1 (PValidator, mkValidator, validatorHash)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   mint,
   output,
@@ -37,9 +35,6 @@ import Plutarch.Context (
  )
 import PlutusLedgerApi.V1 (
   Data,
-  ScriptContext (ScriptContext),
-  ScriptPurpose (Spending),
-  TxInfo,
   TxOutRef (TxOutRef),
   ValidatorHash,
   Value,
@@ -54,7 +49,7 @@ import Sample.Shared (
   minAda,
  )
 import Test.Specification (SpecificationTree, testValidator)
-import Test.Util (pubKeyHashes, sortValue, validatorHashes, withOptional)
+import Test.Util (CombinableBuilder, mkSpending, pubKeyHashes, sortValue, validatorHashes, withOptional)
 
 --------------------------------------------------------------------------------
 
@@ -131,13 +126,10 @@ governorRef =
     "6cce6dfbb697f9e2c4fe9786bb576eb7bd6cbcf7801a4ba13d596006c2d5b957"
     1
 
-governorScriptPurpose :: ScriptPurpose
-governorScriptPurpose = Spending governorRef
-
 governorRedeemer :: GovernorRedeemer
 governorRedeemer = MutateGovernor
 
-mkGovernorBuilder :: GovernorParameters -> BaseBuilder
+mkGovernorBuilder :: forall b. CombinableBuilder b => GovernorParameters -> b
 mkGovernorBuilder ps =
   let gst = Value.assetClassValue govAssetClass 1
       value = sortValue $ gst <> minAda
@@ -179,7 +171,7 @@ mkGATValue v q =
         (validatorHashToTokenName gatOwner)
         q
 
-mkMockEffectBuilder :: MockEffectParameters -> BaseBuilder
+mkMockEffectBuilder :: forall b. CombinableBuilder b => MockEffectParameters -> b
 mkMockEffectBuilder ps =
   let mkGATValue' = mkGATValue ps.gatValidity
       inputValue = mkGATValue' 1
@@ -200,13 +192,12 @@ mkMockEffectBuilder ps =
 
 --------------------------------------------------------------------------------
 
-mutate :: ParameterBundle -> TxInfo
+mutate :: forall b. CombinableBuilder b => ParameterBundle -> b
 mutate pb =
-  buildTxInfoUnsafe $
-    mconcat
-      [ mkGovernorBuilder pb.governorParameters
-      , mkMockEffectBuilder pb.mockEffectParameters
-      ]
+  mconcat
+    [ mkGovernorBuilder pb.governorParameters
+    , mkMockEffectBuilder pb.mockEffectParameters
+    ]
 
 --------------------------------------------------------------------------------
 
@@ -218,10 +209,7 @@ mkTestCase name pb (Validity forGov) =
     (governorValidator governor)
     governorInputDatum
     governorRedeemer
-    ( ScriptContext
-        (mutate pb)
-        governorScriptPurpose
-    )
+    (mkSpending mutate pb governorRef)
 
 --------------------------------------------------------------------------------
 
diff --git a/agora-specs/Sample/Proposal/Advance.hs b/agora-specs/Sample/Proposal/Advance.hs
index 28ec0e9..8c2665c 100644
--- a/agora-specs/Sample/Proposal/Advance.hs
+++ b/agora-specs/Sample/Proposal/Advance.hs
@@ -79,8 +79,6 @@ import Data.List (sort)
 import Data.Maybe (catMaybes, fromJust)
 import Data.Tagged (Tagged (..), untag)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   mint,
   output,
@@ -97,9 +95,6 @@ import PlutusLedgerApi.V1 (
   POSIXTime,
   POSIXTimeRange,
   PubKeyHash,
-  ScriptContext (ScriptContext),
-  ScriptPurpose (Minting, Spending),
-  TxInfo,
   TxOutRef (TxOutRef),
   ValidatorHash,
  )
@@ -131,9 +126,12 @@ import Test.Specification (
   testValidator,
  )
 import Test.Util (
+  CombinableBuilder,
   closedBoundedInterval,
   datumHash,
   groupsOfN,
+  mkMinting,
+  mkSpending,
   pubKeyHashes,
   sortValue,
   toDatum,
@@ -264,7 +262,7 @@ mkProposalOutputDatum ps =
 proposalRef :: TxOutRef
 proposalRef = TxOutRef proposalTxRef 1
 
-mkProposalBuilder :: ProposalParameters -> BaseBuilder
+mkProposalBuilder :: forall b. CombinableBuilder b => ProposalParameters -> b
 mkProposalBuilder ps =
   let pst = Value.singleton proposalPolicySymbol "" 1
       value = sortValue $ minAda <> pst
@@ -280,10 +278,6 @@ mkProposalBuilder ps =
               . withValue value
         ]
 
--- | Script purpose of the proposal validator.
-proposalScriptPurpose :: ScriptPurpose
-proposalScriptPurpose = Spending proposalRef
-
 {- | The proposal redeemer used to spend the proposal UTXO, which is always
       'AdvanceProposal' in this case.
 -}
@@ -327,7 +321,7 @@ getStakeInputDatumAt ps = (!!) (mkStakeInputDatums ps)
 mkStakeRef :: Index -> TxOutRef
 mkStakeRef = TxOutRef stakeTxRef . (+ 3) . fromIntegral
 
-mkStakeBuilder :: StakeParameters -> BaseBuilder
+mkStakeBuilder :: forall b. CombinableBuilder b => StakeParameters -> b
 mkStakeBuilder ps =
   let perStakeValue =
         sortValue $
@@ -360,10 +354,6 @@ mkStakeBuilder ps =
           (mkStakeInputDatums ps)
           (mkStakeOutputDatums ps)
 
--- | Script purpose of the stake validator, given which stake we want to spend.
-getStakeScriptPurposeAt :: Index -> ScriptPurpose
-getStakeScriptPurposeAt = Spending . mkStakeRef
-
 {- | The proposal redeemer used to spend the stake UTXO, which is always
       'WitnessStake' in this case.
 -}
@@ -394,7 +384,7 @@ mkGovernorOutputDatum ps =
 governorRef :: TxOutRef
 governorRef = TxOutRef governorTxRef 2
 
-mkGovernorBuilder :: GovernorParameters -> BaseBuilder
+mkGovernorBuilder :: forall b. CombinableBuilder b => GovernorParameters -> b
 mkGovernorBuilder ps =
   let gst = Value.assetClassValue govAssetClass 1
       value = sortValue $ gst <> minAda
@@ -411,9 +401,6 @@ mkGovernorBuilder ps =
               . withDatum (mkGovernorOutputDatum ps)
         ]
 
-governorScriptPurpose :: ScriptPurpose
-governorScriptPurpose = Spending governorRef
-
 {- | The proposal redeemer used to spend the governor UTXO, which is always
       'MintGATs' in this case.
 -}
@@ -424,11 +411,11 @@ governorRedeemer = MintGATs
 
 -- * Authority Token
 
-mkAuthorityTokenBuilder :: AuthorityTokenParameters -> BaseBuilder
+mkAuthorityTokenBuilder :: forall b. CombinableBuilder b => AuthorityTokenParameters -> b
 mkAuthorityTokenBuilder (AuthorityTokenParameters es mdt invalidTokenName) =
   foldMap perEffect es
   where
-    perEffect :: ValidatorHash -> BaseBuilder
+    perEffect :: ValidatorHash -> b
     perEffect vh =
       let tn =
             if invalidTokenName
@@ -445,9 +432,6 @@ mkAuthorityTokenBuilder (AuthorityTokenParameters es mdt invalidTokenName) =
                   . withValue value
             ]
 
-authorityTokenScriptPurepose :: ScriptPurpose
-authorityTokenScriptPurepose = Minting authorityTokenSymbol
-
 authorityTokenRedeemer :: ()
 authorityTokenRedeemer = ()
 
@@ -455,19 +439,20 @@ authorityTokenRedeemer = ()
 
 -- | Create a 'TxInfo' that update the status of a proposal.
 advance ::
+  forall b.
+  CombinableBuilder b =>
   ParameterBundle ->
-  TxInfo
+  b
 advance pb =
   let mkBuilderMaybe = maybe mempty
-   in buildTxInfoUnsafe $
-        mconcat
-          [ mkProposalBuilder pb.proposalParameters
-          , mkStakeBuilder pb.stakeParameters
-          , mkBuilderMaybe mkGovernorBuilder pb.governorParameters
-          , mkBuilderMaybe mkAuthorityTokenBuilder pb.authorityTokenParameters
-          , timeRange pb.transactionTimeRange
-          , maybe mempty signedWith pb.extraSignature
-          ]
+   in mconcat
+        [ mkProposalBuilder pb.proposalParameters
+        , mkStakeBuilder pb.stakeParameters
+        , mkBuilderMaybe mkGovernorBuilder pb.governorParameters
+        , mkBuilderMaybe mkAuthorityTokenBuilder pb.authorityTokenParameters
+        , timeRange pb.transactionTimeRange
+        , maybe mempty signedWith pb.extraSignature
+        ]
 
 --------------------------------------------------------------------------------
 
@@ -479,13 +464,14 @@ mkTestTree ::
   ParameterBundle ->
   Validity ->
   SpecificationTree
-mkTestTree name params val =
+mkTestTree name pb val =
   group name $ catMaybes [proposal, stake, governor, authority]
   where
-    txInfo = advance params
+    spend = mkSpending advance pb
+    mint = mkMinting advance pb
 
     proposal =
-      let proposalInputDatum = mkProposalInputDatum params.proposalParameters
+      let proposalInputDatum = mkProposalInputDatum pb.proposalParameters
        in Just $
             testValidator
               val.forProposalValidator
@@ -493,10 +479,7 @@ mkTestTree name params val =
               (proposalValidator Shared.proposal)
               proposalInputDatum
               proposalRedeemer
-              ( ScriptContext
-                  txInfo
-                  proposalScriptPurpose
-              )
+              (spend proposalRef)
 
     stake =
       let idx = 0
@@ -505,11 +488,9 @@ mkTestTree name params val =
               val.forStakeValidator
               "stake"
               (stakeValidator Shared.stake)
-              (getStakeInputDatumAt params.stakeParameters idx)
+              (getStakeInputDatumAt pb.stakeParameters idx)
               stakeRedeemer
-              ( ScriptContext
-                  txInfo
-                  (getStakeScriptPurposeAt idx)
+              ( spend (mkStakeRef idx)
               )
 
     governor =
@@ -519,11 +500,8 @@ mkTestTree name params val =
         (governorValidator Shared.governor)
         governorInputDatum
         governorRedeemer
-        ( ScriptContext
-            txInfo
-            governorScriptPurpose
-        )
-        <$ params.governorParameters
+        (spend governorRef)
+        <$ pb.governorParameters
 
     authority =
       testPolicy
@@ -531,11 +509,8 @@ mkTestTree name params val =
         "authority"
         (authorityTokenPolicy $ AuthorityToken Shared.govAssetClass)
         authorityTokenRedeemer
-        ( ScriptContext
-            txInfo
-            authorityTokenScriptPurepose
-        )
-        <$ (params.authorityTokenParameters)
+        (mint authorityTokenSymbol)
+        <$ (pb.authorityTokenParameters)
 
 mkTestTree' ::
   String ->
diff --git a/agora-specs/Sample/Proposal/Cosign.hs b/agora-specs/Sample/Proposal/Cosign.hs
index a344af3..4922c04 100644
--- a/agora-specs/Sample/Proposal/Cosign.hs
+++ b/agora-specs/Sample/Proposal/Cosign.hs
@@ -40,8 +40,6 @@ import Data.Default (def)
 import Data.List (sort)
 import Data.Tagged (Tagged, untag)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   output,
   script,
@@ -49,16 +47,13 @@ import Plutarch.Context (
   timeRange,
   txId,
   withDatum,
-  withRefIndex,
+  withOutRef,
   withTxId,
   withValue,
  )
 import PlutusLedgerApi.V1 (
   POSIXTimeRange,
   PubKeyHash,
-  ScriptContext (ScriptContext),
-  ScriptPurpose (Spending),
-  TxInfo,
   TxOutRef (..),
   Value,
  )
@@ -80,7 +75,7 @@ import Test.Specification (
   group,
   testValidator,
  )
-import Test.Util (closedBoundedInterval, pubKeyHashes, sortValue)
+import Test.Util (CombinableBuilder, closedBoundedInterval, mkSpending, pubKeyHashes, sortValue)
 
 -- | Parameters for cosigning a proposal.
 data Parameters = Parameters
@@ -138,8 +133,8 @@ mkStakeInputDatums :: Parameters -> [StakeDatum]
 mkStakeInputDatums = fmap (\pk -> StakeDatum perStakedGTs pk []) . newCosigners
 
 -- | Create a 'TxInfo' that tries to cosign a proposal with new cosigners.
-cosign :: Parameters -> TxInfo
-cosign ps = buildTxInfoUnsafe builder
+cosign :: forall b. CombinableBuilder b => Parameters -> b
+cosign ps = builder
   where
     pst = Value.singleton proposalPolicySymbol "" 1
     sst = Value.assetClassValue stakeAssetClass 1
@@ -158,7 +153,6 @@ cosign ps = buildTxInfoUnsafe builder
             (untag perStakedGTs)
           <> sst
 
-    stakeBuilder :: BaseBuilder
     stakeBuilder =
       foldMap
         ( \(stakeDatum, refIdx) ->
@@ -166,13 +160,13 @@ cosign ps = buildTxInfoUnsafe builder
                   if ps.alterOutputStakes
                     then stakeDatum {stakedAmount = 0}
                     else stakeDatum
-             in mconcat @BaseBuilder
+             in mconcat
                   [ input $
                       script stakeValidatorHash
                         . withValue stakeValue
                         . withDatum stakeDatum
                         . withTxId stakeTxRef
-                        . withRefIndex refIdx
+                        . withOutRef (mkStakeRef refIdx)
                   , output $
                       script stakeValidatorHash
                         . withValue stakeValue
@@ -182,7 +176,7 @@ cosign ps = buildTxInfoUnsafe builder
         )
         $ zip
           stakeInputDatums
-          [2 ..]
+          [0 ..]
 
     ---
 
@@ -192,7 +186,6 @@ cosign ps = buildTxInfoUnsafe builder
     proposalOutputDatum :: ProposalDatum
     proposalOutputDatum = mkProposalOutputDatum ps
 
-    proposalBuilder :: BaseBuilder
     proposalBuilder =
       mconcat
         [ input $
@@ -200,7 +193,7 @@ cosign ps = buildTxInfoUnsafe builder
               . withValue pst
               . withDatum proposalInputDatum
               . withTxId proposalTxRef
-              . withRefIndex proposalRefIdx
+              . withOutRef proposalRef
         , output $
             script proposalValidatorHash
               . withValue (sortValue (pst <> minAda))
@@ -217,7 +210,6 @@ cosign ps = buildTxInfoUnsafe builder
 
     ---
 
-    builder :: BaseBuilder
     builder =
       mconcat
         [ txId "05c67819fc3381a2052b929ab439244b7b5fe3b3bd07f2134055bbbb21bd9e52"
@@ -231,21 +223,15 @@ proposalRefIdx :: Integer
 proposalRefIdx = 1
 
 -- | Spend the proposal ST.
-proposalScriptPurpose :: ScriptPurpose
-proposalScriptPurpose =
-  Spending
-    ( TxOutRef
-        proposalTxRef
-        proposalRefIdx
-    )
+proposalRef :: TxOutRef
+proposalRef = TxOutRef proposalTxRef proposalRefIdx
 
 -- | Consume the given stake.
-mkStakeScriptPurpose :: Int -> ScriptPurpose
-mkStakeScriptPurpose idx =
-  Spending $
-    TxOutRef
-      stakeTxRef
-      $ proposalRefIdx + 1 + fromIntegral idx
+mkStakeRef :: Int -> TxOutRef
+mkStakeRef idx =
+  TxOutRef
+    stakeTxRef
+    $ proposalRefIdx + 1 + fromIntegral idx
 
 -- | Create a proposal redeemer which cosigns with the new cosginers.
 mkProposalRedeemer :: Parameters -> ProposalRedeemer
@@ -321,7 +307,7 @@ mkTestTree ::
   SpecificationTree
 mkTestTree name ps isValid = group name [proposal, stake]
   where
-    txInfo = cosign ps
+    spend = mkSpending cosign ps
 
     proposal =
       let proposalInputDatum = mkProposalInputDatum ps
@@ -331,10 +317,7 @@ mkTestTree name ps isValid = group name [proposal, stake]
             (proposalValidator Shared.proposal)
             proposalInputDatum
             (mkProposalRedeemer ps)
-            ( ScriptContext
-                txInfo
-                proposalScriptPurpose
-            )
+            (spend proposalRef)
 
     stake =
       let idx = 0
@@ -346,7 +329,4 @@ mkTestTree name ps isValid = group name [proposal, stake]
             (stakeValidator Shared.stake)
             stakeInputDatum
             stakeRedeemer
-            ( ScriptContext
-                txInfo
-                (mkStakeScriptPurpose idx)
-            )
+            (spend $ mkStakeRef idx)
diff --git a/agora-specs/Sample/Proposal/Create.hs b/agora-specs/Sample/Proposal/Create.hs
index 8374920..6ec1fac 100644
--- a/agora-specs/Sample/Proposal/Create.hs
+++ b/agora-specs/Sample/Proposal/Create.hs
@@ -45,8 +45,6 @@ import Data.Coerce (coerce)
 import Data.Default (Default (def))
 import Data.Tagged (Tagged, untag)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   mint,
   output,
@@ -63,9 +61,6 @@ import PlutusLedgerApi.V1 (
   POSIXTime (POSIXTime),
   POSIXTimeRange,
   PubKeyHash,
-  ScriptContext (ScriptContext),
-  ScriptPurpose (Minting, Spending),
-  TxInfo,
   TxOutRef (TxOutRef),
   ValidatorHash,
   always,
@@ -88,7 +83,7 @@ import Sample.Shared (
  )
 import Sample.Shared qualified as Shared
 import Test.Specification (SpecificationTree, group, testPolicy, testValidator)
-import Test.Util (closedBoundedInterval, sortValue)
+import Test.Util (CombinableBuilder, closedBoundedInterval, mkMinting, mkSpending, sortValue)
 
 -- | Parameters for creating a proposal.
 data Parameters = Parameters
@@ -269,8 +264,8 @@ governorRef = TxOutRef "0b2086cbf8b6900f8cb65e012de4516cb66b5cb08a9aaba12a8b88be
 --------------------------------------------------------------------------------
 
 -- | Create a 'TxInfo' that spends a stake to create a new proposal.
-createProposal :: Parameters -> TxInfo
-createProposal ps = buildTxInfoUnsafe builder
+createProposal :: forall b. CombinableBuilder b => Parameters -> b
+createProposal ps = builder
   where
     pst = Value.singleton proposalPolicySymbol "" 1
     sst = Value.assetClassValue stakeAssetClass 1
@@ -296,7 +291,6 @@ createProposal ps = buildTxInfoUnsafe builder
 
     ---
 
-    builder :: BaseBuilder
     builder =
       mconcat
         [ txId "0b2086cbf8b6900f8cb65e012de4516cb66b5cb08a9aaba12a8b88be"
@@ -426,7 +420,8 @@ mkTestTree
   validForStakeValidator =
     group name [proposalTest, governorTest, stakeTest]
     where
-      txInfo = createProposal ps
+      mint = mkMinting createProposal ps
+      spend = mkSpending createProposal ps
 
       proposalTest =
         testPolicy
@@ -434,7 +429,7 @@ mkTestTree
           "proposal"
           (proposalPolicy Shared.proposal.governorSTAssetClass)
           proposalPolicyRedeemer
-          (ScriptContext txInfo (Minting proposalPolicySymbol))
+          (mint proposalPolicySymbol)
 
       governorTest =
         testValidator
@@ -443,11 +438,7 @@ mkTestTree
           (governorValidator Shared.governor)
           governorInputDatum
           governorRedeemer
-          ( ScriptContext
-              txInfo
-              (Spending governorRef)
-          )
-
+          (spend governorRef)
       stakeTest =
         testValidator
           validForStakeValidator
@@ -455,7 +446,4 @@ mkTestTree
           (stakeValidator Shared.stake)
           (mkStakeInputDatum ps)
           stakeRedeemer
-          ( ScriptContext
-              txInfo
-              (Spending stakeRef)
-          )
+          (spend stakeRef)
diff --git a/agora-specs/Sample/Proposal/UnlockStake.hs b/agora-specs/Sample/Proposal/UnlockStake.hs
index 3165a5e..e5b47d6 100644
--- a/agora-specs/Sample/Proposal/UnlockStake.hs
+++ b/agora-specs/Sample/Proposal/UnlockStake.hs
@@ -40,8 +40,6 @@ import Agora.Stake.Scripts (stakeValidator)
 import Data.Default.Class (Default (def))
 import Data.Tagged (Tagged (..), untag)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   output,
   script,
@@ -54,9 +52,6 @@ import Plutarch.Context (
 import PlutusLedgerApi.V1 (
   DatumHash,
   PubKeyHash,
-  ScriptContext (..),
-  ScriptPurpose (Spending),
-  TxInfo (..),
   TxOutRef (..),
   ValidatorHash,
  )
@@ -74,7 +69,7 @@ import Sample.Shared (
  )
 import Sample.Shared qualified as Shared
 import Test.Specification (SpecificationTree, group, testValidator)
-import Test.Util (sortValue, updateMap)
+import Test.Util (CombinableBuilder, mkSpending, sortValue, updateMap)
 
 --------------------------------------------------------------------------------
 
@@ -249,7 +244,7 @@ mkProposalDatumPair params pid =
           getProposalVotes votesTemplate
 
 -- | Create a 'TxInfo' that tries to unlock a stake.
-unlockStake :: Parameters -> TxInfo
+unlockStake :: forall b. CombinableBuilder b => Parameters -> b
 unlockStake ps =
   let pst = Value.singleton proposalPolicySymbol "" 1
       sst = Value.assetClassValue stakeAssetClass 1
@@ -260,7 +255,6 @@ unlockStake ps =
         foldMap
           ( \((i, o), idx) ->
               mconcat
-                @BaseBuilder
                 [ input $
                     script proposalValidatorHash
                       . withValue pst
@@ -288,7 +282,7 @@ unlockStake ps =
       sOutDatum = mkStakeOutputDatum ps
 
       stakes =
-        mconcat @BaseBuilder
+        mconcat
           [ input $
               script stakeValidatorHash
                 . withValue stakeValue
@@ -301,13 +295,13 @@ unlockStake ps =
           ]
 
       builder =
-        mconcat @BaseBuilder
+        mconcat
           [ txId "388bc0b897b3dadcd479da4c88291de4113a50b72ddbed001faf7fc03f11bc52"
           , proposals
           , stakes
           , signedWith defOwner
           ]
-   in buildTxInfoUnsafe builder
+   in builder
 
 -- | Reference to the stake UTXO.
 stakeRef :: TxOutRef
@@ -523,7 +517,7 @@ mkAlterStakeParameters nProposals = do
 mkTestTree :: String -> Parameters -> Bool -> SpecificationTree
 mkTestTree name ps isValid = group name [stake, proposal]
   where
-    txInfo = unlockStake ps
+    spend = mkSpending unlockStake ps
 
     stake =
       testValidator
@@ -532,7 +526,7 @@ mkTestTree name ps isValid = group name [stake, proposal]
         (stakeValidator Shared.stake)
         (mkStakeInputDatum ps)
         stakeRedeemer
-        (ScriptContext txInfo (Spending stakeRef))
+        (spend stakeRef)
 
     proposal =
       let idx = 0
@@ -544,4 +538,4 @@ mkTestTree name ps isValid = group name [stake, proposal]
             (proposalValidator Shared.proposal)
             (mkProposalInputDatum ps pid)
             proposalRedeemer
-            (ScriptContext txInfo (Spending ref))
+            (spend ref)
diff --git a/agora-specs/Sample/Proposal/Vote.hs b/agora-specs/Sample/Proposal/Vote.hs
index f841dd2..765cd82 100644
--- a/agora-specs/Sample/Proposal/Vote.hs
+++ b/agora-specs/Sample/Proposal/Vote.hs
@@ -33,8 +33,6 @@ import Agora.Stake.Scripts (stakeValidator)
 import Data.Default (Default (def))
 import Data.Tagged (Tagged (Tagged), untag)
 import Plutarch.Context (
-  BaseBuilder,
-  buildTxInfoUnsafe,
   input,
   output,
   script,
@@ -47,9 +45,6 @@ import Plutarch.Context (
  )
 import PlutusLedgerApi.V1 (
   PubKeyHash,
-  ScriptContext (..),
-  ScriptPurpose (Spending),
-  TxInfo,
   TxOutRef (TxOutRef),
  )
 import PlutusLedgerApi.V1.Value qualified as Value
@@ -71,7 +66,7 @@ import Test.Specification (
   testValidator,
   validatorSucceedsWith,
  )
-import Test.Util (closedBoundedInterval, sortValue, updateMap)
+import Test.Util (CombinableBuilder, closedBoundedInterval, mkSpending, sortValue, updateMap)
 
 -- | Reference to the proposal UTXO.
 proposalRef :: TxOutRef
@@ -152,7 +147,7 @@ stakeRedeemer :: StakeRedeemer
 stakeRedeemer = PermitVote
 
 -- | Create a valid transaction that votes on a propsal, given the parameters.
-vote :: Parameters -> TxInfo
+vote :: forall b. CombinableBuilder b => Parameters -> b
 vote params =
   let pst = Value.singleton proposalPolicySymbol "" 1
       sst = Value.assetClassValue stakeAssetClass 1
@@ -203,7 +198,6 @@ vote params =
             <> Value.assetClassValue (untag stake.gtClassRef) params.voteCount
             <> minAda
 
-      builder :: BaseBuilder
       builder =
         mconcat
           [ txId "827598fb2d69a896bbd9e645bb14c307df907f422b39eecbe4d6329bc30b428c"
@@ -228,7 +222,7 @@ vote params =
                 . withValue stakeValue
                 . withDatum stakeOutputDatum
           ]
-   in buildTxInfoUnsafe builder
+   in builder
 
 ---
 
@@ -248,7 +242,7 @@ validVoteParameters =
 mkTestTree :: String -> Parameters -> Bool -> SpecificationTree
 mkTestTree name ps isValid = group name [proposal, stake]
   where
-    txInfo = vote ps
+    spend = mkSpending vote ps
 
     proposal =
       testValidator
@@ -257,10 +251,7 @@ mkTestTree name ps isValid = group name [proposal, stake]
         (proposalValidator Shared.proposal)
         proposalInputDatum
         (mkProposalRedeemer ps)
-        ( ScriptContext
-            txInfo
-            (Spending proposalRef)
-        )
+        (spend proposalRef)
 
     stake =
       let stakeInputDatum = mkStakeInputDatum ps
@@ -269,7 +260,4 @@ mkTestTree name ps isValid = group name [proposal, stake]
             (stakeValidator Shared.stake)
             stakeInputDatum
             stakeRedeemer
-            ( ScriptContext
-                txInfo
-                (Spending stakeRef)
-            )
+            (spend stakeRef)
diff --git a/agora-specs/Sample/Stake.hs b/agora-specs/Sample/Stake.hs
index 88e5dc7..ba1a835 100644
--- a/agora-specs/Sample/Stake.hs
+++ b/agora-specs/Sample/Stake.hs
@@ -40,8 +40,9 @@ import Plutarch.Context (
   signedWith,
   txId,
   withDatum,
-  withSpending,
-  withTxId,
+  withMinting,
+  withOutRef,
+  withSpendingOutRef,
   withValue,
  )
 import PlutusLedgerApi.V1 (
@@ -53,6 +54,7 @@ import PlutusLedgerApi.V1 (
   TxInfo (txInfoData, txInfoSignatories),
   ValidatorHash (ValidatorHash),
  )
+import PlutusLedgerApi.V1.Contexts (TxOutRef (..))
 import PlutusLedgerApi.V1.Value qualified as Value (
   assetClassValue,
   singleton,
@@ -86,6 +88,7 @@ stakeCreation =
               script stakeValidatorHash
                 . withValue (st <> Value.singleton "da8c30857834c6ae7203935b89278c532b3995245295456f993e1d24" "LQ" 424242424242)
                 . withDatum datum
+          , withMinting stakeSymbol
           ]
    in buildMintingUnsafe builder
 
@@ -130,6 +133,9 @@ stakeDepositWithdraw config =
       stakeAfter :: StakeDatum
       stakeAfter = stakeBefore {stakedAmount = stakeBefore.stakedAmount + config.delta}
 
+      stakeRef :: TxOutRef
+      stakeRef = TxOutRef "0ffef57e30cc604342c738e31e0451593837b313e7bfb94b0922b142782f98e6" 1
+
       builder :: SpendingBuilder
       builder =
         mconcat
@@ -140,14 +146,11 @@ stakeDepositWithdraw config =
               script stakeValidatorHash
                 . withValue (st <> Value.assetClassValue (untag stake.gtClassRef) (untag stakeBefore.stakedAmount))
                 . withDatum stakeAfter
-                . withTxId "0b2086cbf8b6900f8cb65e012de4516cb66b5cb08a9aaba12a8b88be"
+                . withOutRef stakeRef
           , output $
               script stakeValidatorHash
                 . withValue (st <> Value.assetClassValue (untag stake.gtClassRef) (untag stakeAfter.stakedAmount))
                 . withDatum stakeAfter
-          , withSpending $
-              script stakeValidatorHash
-                . withValue (st <> Value.assetClassValue (untag stake.gtClassRef) (untag stakeBefore.stakedAmount))
-                . withDatum stakeAfter
+          , withSpendingOutRef stakeRef
           ]
    in buildSpendingUnsafe builder
diff --git a/agora-specs/Sample/Treasury.hs b/agora-specs/Sample/Treasury.hs
index 632f559..2c3c902 100644
--- a/agora-specs/Sample/Treasury.hs
+++ b/agora-specs/Sample/Treasury.hs
@@ -28,6 +28,7 @@ import Plutarch.Context (
   script,
   signedWith,
   txId,
+  withMinting,
   withTxId,
   withValue,
  )
@@ -67,6 +68,7 @@ baseCtxBuilder =
         , mint (Value.singleton gatCs gatTn (-1))
         , input treasury
         , output treasury
+        , withMinting gatCs
         ]
 
 {- | A `ScriptContext` that should be compatible with treasury
diff --git a/agora-testlib/Test/Util.hs b/agora-testlib/Test/Util.hs
index e7914b7..dff8990 100644
--- a/agora-testlib/Test/Util.hs
+++ b/agora-testlib/Test/Util.hs
@@ -20,6 +20,9 @@ module Test.Util (
   validatorHashes,
   groupsOfN,
   withOptional,
+  mkSpending,
+  mkMinting,
+  CombinableBuilder,
 ) where
 
 --------------------------------------------------------------------------------
@@ -32,9 +35,26 @@ import Data.ByteString qualified as BS
 import Data.ByteString.Char8 qualified as C
 import Data.ByteString.Lazy qualified as ByteString.Lazy
 import Data.List (sortOn)
-import Plutarch.Context (UTXO)
+import Plutarch.Context (
+  Builder,
+  UTXO,
+  buildMintingUnsafe,
+  buildSpendingUnsafe,
+  withMinting,
+  withSpendingOutRef,
+ )
 import Plutarch.Crypto (pblake2b_256)
-import PlutusLedgerApi.V1 (Credential (PubKeyCredential, ScriptCredential), PubKeyHash (..), ValidatorHash (ValidatorHash))
+import PlutusLedgerApi.V1 (
+  Credential (
+    PubKeyCredential,
+    ScriptCredential
+  ),
+  CurrencySymbol,
+  PubKeyHash (..),
+  ScriptContext,
+  TxOutRef,
+  ValidatorHash (ValidatorHash),
+ )
 import PlutusLedgerApi.V1.Interval qualified as PlutusTx
 import PlutusLedgerApi.V1.Scripts (Datum (Datum), DatumHash (DatumHash))
 import PlutusLedgerApi.V1.Value (Value (..))
@@ -168,3 +188,25 @@ withOptional ::
   UTXO
 withOptional f (Just b) = f b
 withOptional _ _ = id
+
+mkSpending ::
+  forall ps.
+  (forall b. (Monoid b, Builder b) => ps -> b) ->
+  ps ->
+  TxOutRef ->
+  ScriptContext
+mkSpending mkBuilder ps oref =
+  buildSpendingUnsafe $
+    mkBuilder ps <> withSpendingOutRef oref
+
+mkMinting ::
+  forall ps.
+  (forall b. (Monoid b, Builder b) => ps -> b) ->
+  ps ->
+  CurrencySymbol ->
+  ScriptContext
+mkMinting mkBuilder ps cs =
+  buildMintingUnsafe $
+    mkBuilder ps <> withMinting cs
+
+type CombinableBuilder b = (Monoid b, Builder b)
diff --git a/bench.csv b/bench.csv
index e5c5b9b..58ff462 100644
--- a/bench.csv
+++ b/bench.csv
@@ -5,8 +5,8 @@ Agora/Effects/Treasury Withdrawal Effect/effect/Mixed Assets,455817227,1103968,3
 Agora/Effects/Governor Mutation Effect/validator/valid new governor datum/governor validator should pass,93089688,256879,8290
 Agora/Effects/Governor Mutation Effect/validator/valid new governor datum/effect validator should pass,112671240,312571,3751
 Agora/Stake/policy/stakeCreation,51008580,149029,2522
-Agora/Stake/validator/stakeDepositWithdraw deposit,183506412,498838,4745
-Agora/Stake/validator/stakeDepositWithdraw withdraw,183506412,498838,4733
+Agora/Stake/validator/stakeDepositWithdraw deposit,183506412,498838,4753
+Agora/Stake/validator/stakeDepositWithdraw withdraw,183506412,498838,4741
 Agora/Proposal/policy (proposal creation)/legal/proposal,33689644,100286,2005
 Agora/Proposal/policy (proposal creation)/legal/governor,324511293,861435,8769
 Agora/Proposal/policy (proposal creation)/legal/stake,153960499,403133,5407