diff --git a/CHANGELOG.md b/CHANGELOG.md
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+++ b/CHANGELOG.md
@@ -0,0 +1,15 @@
+# Changelog
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.1.0.0] - 2026-04-25
+
+Initial release.
+[fused-effects](https://hackage.haskell.org/package/fused-effects)
+adapter for [`valiant`](https://hackage.haskell.org/package/valiant).
+Provides a `Valiant` effect, a `ValiantPoolC` carrier (built on
+`ReaderC Pool`), and `Has (Reader Pool) sig m`-constrained smart
+constructors for query, command, and transaction operations.
+
+[0.1.0.0]: https://github.com/joshburgess/valiant/releases/tag/v0.1.0.0
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2026 Josh Burgess
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from this
+   software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,41 @@
+# valiant-fused-effects
+
+[fused-effects](https://hackage.haskell.org/package/fused-effects)
+adapter for [`valiant`](https://hackage.haskell.org/package/valiant).
+
+Provides a `Valiant` effect, a `ValiantPoolC` carrier (built on
+`ReaderC Pool`), and `Has (Reader Pool) sig m`-constrained smart
+constructors.
+
+## Quick start
+
+```haskell
+import Control.Carrier.Lift (runM)
+import Valiant (newPool, defaultPoolConfig, poolConnString)
+import Valiant.FusedEffects
+
+myApp :: (Has (Reader Pool) sig m, MonadIO m) => m [User]
+myApp = do
+  users <- fetchAllF listUsers ()
+  pure users
+
+main :: IO ()
+main = do
+  pool <- newPool defaultPoolConfig { poolConnString = "postgres://..." }
+  users <- runM . runValiantPool pool $ myApp
+  print users
+```
+
+## What you get
+
+- Effect: `data Valiant`
+- Carrier: `type ValiantPoolC m = ReaderC Pool m` with
+  `runValiantPool :: Pool -> ValiantPoolC m a -> m a`
+- Query operations: `fetchOneF`, `fetchAllF`, `fetchScalarF`,
+  `fetchOneOrThrowF`, `fetchExistsF`
+- Command operations: `executeF`, `executeReturningF`, `executeBatchF`
+- Transactions: `withTransactionF`
+- Raw access: `withConnectionF`
+
+See the [valiant tutorial](https://github.com/joshburgess/valiant/blob/main/docs/TUTORIAL.md)
+for `Statement` definitions and the `valiant prepare` workflow.
diff --git a/src/Valiant/FusedEffects.hs b/src/Valiant/FusedEffects.hs
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--- /dev/null
+++ b/src/Valiant/FusedEffects.hs
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+{-# LANGUAGE RankNTypes #-}
+
+-- | Fused-effects adapter for valiant.
+--
+-- Provides an @Valiant@ effect with a pool-based carrier via 'ReaderC'.
+--
+-- @
+-- import Control.Carrier.Lift (runM)
+-- import Valiant.FusedEffects
+--
+-- myApp :: Has Valiant sig m => m [User]
+-- myApp = do
+--   users <- fetchAllF listUsers ()
+--   pure users
+--
+-- main :: IO ()
+-- main = do
+--   pool <- newPool defaultPoolConfig { poolConnString = "..." }
+--   result <- runM . runValiantPool pool $ myApp
+--   print result
+-- @
+module Valiant.FusedEffects
+  ( -- * Effect
+    Valiant (..)
+
+    -- * Carrier
+  , ValiantPoolC
+  , runValiantPool
+
+    -- * Query operations
+  , fetchOneF
+  , fetchAllF
+  , fetchScalarF
+  , fetchOneOrThrowF
+  , fetchExistsF
+
+    -- * Command operations
+  , executeF
+  , executeReturningF
+  , executeBatchF
+
+    -- * Transaction operations
+  , withTransactionF
+
+    -- * Raw access
+  , withConnectionF
+  ) where
+
+import Control.Algebra
+import Control.Carrier.Reader (ReaderC, runReader)
+import Control.Effect.Reader (Reader, ask)
+import Control.Monad.IO.Class (MonadIO, liftIO)
+import Data.Int (Int64)
+import Data.Kind (Type)
+import Valiant (Connection, Pool, Statement, Transaction)
+import Valiant qualified
+import PgWire.Pool (withResource)
+
+------------------------------------------------------------------------
+-- Effect
+------------------------------------------------------------------------
+
+-- | The Valiant database effect for fused-effects.
+data Valiant (m :: Type -> Type) k where
+  FetchOneF :: Statement p r -> p -> Valiant m (Maybe r)
+  FetchAllF :: Statement p r -> p -> Valiant m [r]
+  FetchScalarF :: Statement p r -> p -> Valiant m r
+  FetchOneOrThrowF :: Statement p r -> p -> Valiant m r
+  FetchExistsF :: Statement p r -> p -> Valiant m Bool
+  ExecuteF :: Statement p () -> p -> Valiant m Int64
+  ExecuteReturningF :: Statement p r -> p -> Valiant m (Int64, [r])
+  ExecuteBatchF :: Statement p () -> [p] -> Valiant m Int64
+  WithTransactionF :: (Transaction -> IO a) -> Valiant m a
+  WithConnectionF :: (Connection -> IO a) -> Valiant m a
+
+------------------------------------------------------------------------
+-- Carrier (via ReaderC Pool)
+------------------------------------------------------------------------
+
+-- | Pool-based carrier. Uses 'ReaderC Pool' internally.
+type ValiantPoolC m = ReaderC Pool m
+
+-- | Run the Valiant effect with a connection pool.
+runValiantPool :: Pool -> ValiantPoolC m a -> m a
+runValiantPool = runReader
+
+------------------------------------------------------------------------
+-- Smart constructors (interpret directly via reader + IO)
+------------------------------------------------------------------------
+
+-- | Fetch zero or one row.
+fetchOneF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p r -> p -> m (Maybe r)
+fetchOneF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.fetchOne conn stmt params
+
+-- | Fetch all rows.
+fetchAllF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p r -> p -> m [r]
+fetchAllF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.fetchAll conn stmt params
+
+-- | Fetch exactly one scalar value.
+fetchScalarF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p r -> p -> m r
+fetchScalarF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.fetchScalar conn stmt params
+
+-- | Fetch one row, throwing if none returned.
+fetchOneOrThrowF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p r -> p -> m r
+fetchOneOrThrowF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.fetchOneOrThrow conn stmt params
+
+-- | Check if a query returns any rows.
+fetchExistsF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p r -> p -> m Bool
+fetchExistsF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.fetchExists conn stmt params
+
+-- | Execute a command. Returns rows affected.
+executeF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p () -> p -> m Int64
+executeF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.execute conn stmt params
+
+-- | Execute with RETURNING.
+executeReturningF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p r -> p -> m (Int64, [r])
+executeReturningF stmt params = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.executeReturning conn stmt params
+
+-- | Execute a batch of commands (pipelined).
+executeBatchF :: (Has (Reader Pool) sig m, MonadIO m) => Statement p () -> [p] -> m Int64
+executeBatchF stmt paramsList = do
+  pool <- ask
+  liftIO $ withResource pool $ \conn -> Valiant.executeBatch conn stmt paramsList
+
+-- | Run an action in a transaction.
+withTransactionF :: (Has (Reader Pool) sig m, MonadIO m) => (Transaction -> IO a) -> m a
+withTransactionF action = do
+  pool <- ask
+  liftIO $ Valiant.withTransaction pool action
+
+-- | Run an action with a raw connection.
+withConnectionF :: (Has (Reader Pool) sig m, MonadIO m) => (Connection -> IO a) -> m a
+withConnectionF action = do
+  pool <- ask
+  liftIO $ withResource pool action
diff --git a/test/Main.hs b/test/Main.hs
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--- /dev/null
+++ b/test/Main.hs
@@ -0,0 +1,77 @@
+module Main where
+
+import Control.Carrier.Lift (runM)
+import Data.ByteString (ByteString)
+import Data.ByteString.Char8 qualified as BS8
+import Data.Int (Int32)
+import Data.Text (Text)
+import Valiant (defaultPoolConfig, newPool, closePool)
+import Valiant qualified
+import Valiant.FusedEffects (fetchAllF, fetchOneF, executeF, runValiantPool)
+import PgWire.Pool.Config (PoolConfig (..))
+import System.Environment (lookupEnv)
+import Test.Hspec
+import TestSupport
+
+main :: IO ()
+main = hspec $ do
+  describe "Valiant.FusedEffects" $ do
+    it "fetchAllF returns all rows" $ do
+      withTestConnection $ \conn -> withSchema conn $ do
+        insertTestUsers conn
+        pool <- mkPool
+        result <- runM . runValiantPool pool $ fetchAllF stmtListAll ()
+        closePool pool
+        length result `shouldBe` 5
+
+    it "fetchOneF returns Just for existing row" $ do
+      withTestConnection $ \conn -> withSchema conn $ do
+        insertTestUsers conn
+        pool <- mkPool
+        result <- runM . runValiantPool pool $ fetchOneF stmtSelectOne 1
+        closePool pool
+        case result of
+          Just (_, name, _) -> name `shouldBe` "Alice"
+          Nothing -> expectationFailure "Expected a row"
+
+    it "fetchOneF returns Nothing for missing row" $ do
+      withTestConnection $ \conn -> withSchema conn $ do
+        pool <- mkPool
+        result <- runM . runValiantPool pool $ fetchOneF stmtSelectOne (-1)
+        closePool pool
+        result `shouldBe` (Nothing :: Maybe (Int32, Text, Maybe Text))
+
+    it "executeF returns rows affected" $ do
+      withTestConnection $ \conn -> withSchema conn $ do
+        insertTestUsers conn
+        pool <- mkPool
+        let stmtDel = Valiant.mkStatement "DELETE FROM users_fused_effects WHERE id = $1" [23] [] "<test>" :: Valiant.Statement Int32 ()
+        n <- runM . runValiantPool pool $ executeF stmtDel (1 :: Int32)
+        closePool pool
+        n `shouldBe` 1
+
+    it "composes multiple operations" $ do
+      withTestConnection $ \conn -> withSchema conn $ do
+        insertTestUsers conn
+        pool <- mkPool
+        (users, mUser) <- runM . runValiantPool pool $ do
+          us <- fetchAllF stmtListAll ()
+          mu <- fetchOneF stmtSelectOne 1
+          pure (us, mu)
+        closePool pool
+        length users `shouldBe` 5
+        case mUser of
+          Just (_, name, _) -> name `shouldBe` "Alice"
+          Nothing -> expectationFailure "Expected a row"
+
+mkPool :: IO Valiant.Pool
+mkPool = do
+  url <- requireDatabaseUrl'
+  newPool defaultPoolConfig { poolConnString = url, poolSize = 2, poolAcquireTimeout = 5 }
+
+requireDatabaseUrl' :: IO ByteString
+requireDatabaseUrl' = do
+  mUrl <- lookupEnv "DATABASE_URL"
+  case mUrl of
+    Just url -> pure (BS8.pack url)
+    Nothing -> error "DATABASE_URL is not set."
diff --git a/test/TestSupport.hs b/test/TestSupport.hs
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--- /dev/null
+++ b/test/TestSupport.hs
@@ -0,0 +1,63 @@
+module TestSupport
+  ( withTestConnection
+  , withSchema
+  , insertTestUsers
+  , stmtListAll
+  , stmtSelectOne
+  ) where
+
+import Data.ByteString (ByteString)
+import Data.ByteString.Char8 qualified as BS8
+import Data.Int (Int32)
+import Data.Text (Text)
+import Valiant
+import System.Environment (lookupEnv)
+
+requireDatabaseUrl :: IO ByteString
+requireDatabaseUrl = do
+  mUrl <- lookupEnv "DATABASE_URL"
+  case mUrl of
+    Just url -> pure (BS8.pack url)
+    Nothing -> error "DATABASE_URL is not set."
+
+withTestConnection :: (Connection -> IO a) -> IO a
+withTestConnection action = do
+  url <- requireDatabaseUrl
+  conn <- connectString url
+  result <- action conn
+  close conn
+  pure result
+
+withSchema :: Connection -> IO a -> IO a
+withSchema conn action = do
+  _ <- simpleQuery conn "DROP TABLE IF EXISTS users_fused_effects CASCADE"
+  _ <- simpleQuery conn
+    "CREATE TABLE users_fused_effects (\
+    \  id SERIAL PRIMARY KEY,\
+    \  name TEXT NOT NULL,\
+    \  email TEXT\
+    \)"
+  result <- action
+  _ <- simpleQuery conn "DROP TABLE IF EXISTS users_fused_effects CASCADE"
+  pure result
+
+insertTestUsers :: Connection -> IO ()
+insertTestUsers conn = do
+  _ <- simpleQuery conn
+    "INSERT INTO users_fused_effects (name, email) VALUES \
+    \('Alice', 'alice@example.com'),\
+    \('Bob', 'bob@example.com'),\
+    \('Carol', NULL),\
+    \('Dave', 'dave@example.com'),\
+    \('Eve', 'eve@example.com')"
+  pure ()
+
+stmtListAll :: Statement () (Int32, Text)
+stmtListAll = mkStatement
+  "SELECT id, name FROM users_fused_effects ORDER BY id"
+  [] ["id", "name"] "<test>"
+
+stmtSelectOne :: Statement Int32 (Int32, Text, Maybe Text)
+stmtSelectOne = mkStatement
+  "SELECT id, name, email FROM users_fused_effects WHERE id = $1"
+  [23] ["id", "name", "email"] "<test>"
diff --git a/valiant-fused-effects.cabal b/valiant-fused-effects.cabal
new file mode 100644
--- /dev/null
+++ b/valiant-fused-effects.cabal
@@ -0,0 +1,102 @@
+cabal-version:   3.0
+name:            valiant-fused-effects
+version:         0.1.0.0
+synopsis:        Fused-effects adapter for valiant
+description:
+  Provides an @Valiant@ effect and @ValiantPoolC@ carrier for the
+  @fused-effects@ effect system, enabling compile-time checked SQL
+  queries as an algebraic effect.
+
+  @
+  import Valiant.FusedEffects
+
+  myApp :: Has Valiant sig m => m [User]
+  myApp = do
+    users <- fetchAllF listUsers ()
+    pure users
+
+  main :: IO ()
+  main = do
+    pool <- newPool defaultPoolConfig { poolConnString = "..." }
+    result <- runValiantPool pool myApp
+    print result
+  @
+license:         BSD-3-Clause
+license-file:    LICENSE
+author:          Josh Burgess
+maintainer:      joshburgess.webdev@gmail.com
+category:        Database
+homepage:        https://github.com/joshburgess/valiant
+bug-reports:     https://github.com/joshburgess/valiant/issues
+build-type:      Simple
+extra-doc-files:
+  README.md
+  CHANGELOG.md
+tested-with:     GHC ==9.10.3
+
+source-repository head
+  type:     git
+  location: https://github.com/joshburgess/valiant
+  subdir:   adapters/valiant-fused-effects
+
+flag werror
+  description: Enable -Werror for development builds.
+  default:     False
+  manual:      True
+
+common warnings
+  ghc-options: -Wall -Wcompat -Wno-unticked-promoted-constructors -funbox-strict-fields -fspecialise-aggressively
+  if flag(werror)
+    ghc-options: -Werror
+
+library
+  import:           warnings
+  hs-source-dirs:   src
+  default-language: GHC2021
+  default-extensions:
+    DerivingStrategies
+    FlexibleContexts
+    FlexibleInstances
+    GADTs
+    GeneralizedNewtypeDeriving
+    KindSignatures
+    LambdaCase
+    MultiParamTypeClasses
+    OverloadedStrings
+    ScopedTypeVariables
+    StrictData
+    TypeOperators
+    UndecidableInstances
+
+  exposed-modules:
+    Valiant.FusedEffects
+
+  build-depends:
+    , base            >=4.17 && <5
+    , fused-effects   >=1.1  && <1.3
+    , valiant         >=0.1  && <0.2
+    , pg-wire         >=0.1  && <0.2
+
+test-suite valiant-fused-effects-test
+  import:           warnings
+  type:             exitcode-stdio-1.0
+  hs-source-dirs:   test
+  main-is:          Main.hs
+  default-language: GHC2021
+  default-extensions:
+    OverloadedStrings
+
+  ghc-options: -rtsopts "-with-rtsopts=-K8K"
+
+  other-modules:
+    TestSupport
+
+  build-depends:
+    , base            >=4.17 && <5
+    , bytestring      >=0.11 && <0.13
+    , fused-effects   >=1.1  && <1.3
+    , hspec           >=2.11 && <2.13
+    , valiant
+    , valiant-fused-effects
+    , pg-wire
+    , text            >=2.0  && <2.2