diff --git a/Shakefile.hs b/Shakefile.hs
--- a/Shakefile.hs
+++ b/Shakefile.hs
@@ -37,8 +37,9 @@
 
   -- | sanity
   --
-  fake "." pats "sanity" $ const $
-    need [ "build-error", "lint", "weed" ]
+  fake "." pats "sanity" $ const $ do
+    need [ "build-error" ]
+    need [ "lint", "weed" ]
 
   -- | Default things to run.
   --
diff --git a/src/Network/AWS/Wolf/Act.hs b/src/Network/AWS/Wolf/Act.hs
--- a/src/Network/AWS/Wolf/Act.hs
+++ b/src/Network/AWS/Wolf/Act.hs
@@ -14,38 +14,33 @@
 import Network.AWS.Wolf.Ctx
 import Network.AWS.Wolf.File
 import Network.AWS.Wolf.Prelude
+import Network.AWS.Wolf.S3
 import Network.AWS.Wolf.SWF
 import Network.AWS.Wolf.Types
 import System.Directory
 import System.Exit
 import System.Process
 
--- | S3 copy call.
---
-cp :: MonadIO m => FilePath -> FilePath -> m ()
-cp f t = liftIO $ callProcess "aws" [ "s3", "cp", "--quiet", "--recursive", f, t ]
-
--- | Key to download and upload objects from.
---
-key :: MonadAmazonStore c m => m FilePath
-key = do
-  b <- view cBucket <$> view ccConf
-  p <- view ascPrefix
-  pure $ "s3:/" -/- textToString b -/- textToString p
-
 -- | Download artifacts to the store input directory.
 --
 download :: MonadAmazonStore c m => FilePath -> m ()
 download dir = do
   traceInfo "download" [ "dir" .= dir ]
-  flip cp dir =<< key
+  ks <- listArtifacts
+  forM_ ks $ \k -> do
+    traceInfo "download" [ "dir" .= dir, "key" .= k ]
+    touchDirectory (dir </> k)
+    getArtifact (dir </> k) k
 
 -- | Upload artifacts from the store output directory.
 --
 upload :: MonadAmazonStore c m => FilePath -> m ()
 upload dir = do
   traceInfo "upload" [ "dir" .= dir ]
-  cp dir =<< key
+  ks <- findRelativeFiles dir
+  forM_ ks $ \k -> do
+    traceInfo "upload" [ "dir" .= dir, "key" .= k ]
+    putArtifact (dir </> k) k
 
 -- | callCommand wrapper that maybe returns an exception.
 --
diff --git a/src/Network/AWS/Wolf/Ctx.hs b/src/Network/AWS/Wolf/Ctx.hs
--- a/src/Network/AWS/Wolf/Ctx.hs
+++ b/src/Network/AWS/Wolf/Ctx.hs
@@ -43,7 +43,7 @@
 --
 topSomeExceptionCatch :: MonadStatsCtx c m => SomeException -> m a
 topSomeExceptionCatch ex = do
-  statsIncrement "exception" [ "reason" =. textFromString (displayException ex) ]
+  statsIncrement "wolf.exception" [ "reason" =. textFromString (displayException ex) ]
   throwIO ex
 
 -- | Run bottom TransT.
diff --git a/src/Network/AWS/Wolf/File.hs b/src/Network/AWS/Wolf/File.hs
--- a/src/Network/AWS/Wolf/File.hs
+++ b/src/Network/AWS/Wolf/File.hs
@@ -4,7 +4,9 @@
 -- | Files, directories, and encoding / decoding file functions.
 --
 module Network.AWS.Wolf.File
-  ( dataDirectory
+  ( findRelativeFiles
+  , touchDirectory
+  , dataDirectory
   , storeDirectory
   , inputDirectory
   , outputDirectory
@@ -20,9 +22,24 @@
 import qualified Data.ByteString.Lazy     as LBS
 import           Data.Time
 import           Data.Yaml                hiding (encode)
-import           Network.AWS.Wolf.Prelude
+import           Network.AWS.Wolf.Prelude hiding (find)
 import           System.Directory
+import           System.FilePath
+import           System.FilePath.Find
 import           System.IO                hiding (readFile, writeFile)
+
+-- | Recursively find all files under a directory.
+--
+findRelativeFiles :: MonadIO m => FilePath -> m [FilePath]
+findRelativeFiles dir = do
+  files <- liftIO $ find always (fileType ==? RegularFile) dir
+  pure $ makeRelative dir <$> files
+
+-- | Create parent directory of file if missing.
+--
+touchDirectory :: MonadIO m => FilePath -> m ()
+touchDirectory =
+  liftIO . createDirectoryIfMissing True . takeDirectory
 
 -- | Determine path to data directory and create it.
 --
diff --git a/src/Network/AWS/Wolf/Prelude.hs b/src/Network/AWS/Wolf/Prelude.hs
--- a/src/Network/AWS/Wolf/Prelude.hs
+++ b/src/Network/AWS/Wolf/Prelude.hs
@@ -10,7 +10,7 @@
   ) where
 
 import Control.Concurrent.Async.Lifted
-import Preamble                        as Exports
+import Preamble                        as Exports hiding (stripPrefix)
 
 -- | Run a list of actions concurrently.
 --
diff --git a/src/Network/AWS/Wolf/S3.hs b/src/Network/AWS/Wolf/S3.hs
new file mode 100644
--- /dev/null
+++ b/src/Network/AWS/Wolf/S3.hs
@@ -0,0 +1,54 @@
+{-# LANGUAGE FlexibleContexts  #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- | S3 Calls.
+--
+module Network.AWS.Wolf.S3
+  ( listArtifacts
+  , getArtifact
+  , putArtifact
+  ) where
+
+import Control.Monad.Trans.AWS
+import Data.Conduit
+import Data.Conduit.Combinators
+import Network.AWS.Data
+import Network.AWS.Data.Body
+import Network.AWS.S3           hiding (cBucket)
+import Network.AWS.Wolf.Ctx
+import Network.AWS.Wolf.Prelude hiding (concatMap)
+import Network.AWS.Wolf.Types
+import System.FilePath
+
+-- | List keys in bucket with prefix.
+--
+listArtifacts :: MonadAmazonStore c m => m [FilePath]
+listArtifacts = do
+  b <- view cBucket <$> view ccConf
+  p <- view ascPrefix
+  runResourceT $ runAmazonCtx $
+    paginate (set loPrefix (pure p) $ listObjects (BucketName b))
+      =$= concatMap ((makeRelative (textToString p) . textToString . toText . view oKey <$>) . view lorsContents)
+      $$  sinkList
+
+-- | Get object in bucket with key.
+--
+getArtifact :: MonadAmazonStore c m => FilePath -> FilePath -> m ()
+getArtifact file key = do
+  b <- view cBucket <$> view ccConf
+  p <- view ascPrefix
+  runResourceT $ runAmazonCtx $ do
+    gors <- send $ getObject (BucketName b) (ObjectKey (p -/- textFromString key))
+    sinkBody (gors ^. gorsBody) (sinkFileBS file)
+
+-- | Put object in bucket with key.
+--
+putArtifact :: MonadAmazonStore c m => FilePath -> FilePath -> m ()
+putArtifact file key = do
+  b <- view cBucket <$> view ccConf
+  p <- view ascPrefix
+  runResourceT $ runAmazonCtx $ do
+    (sha, len) <- sourceFileBS file $$ getZipSink $ (,) <$> ZipSink sinkSHA256 <*> ZipSink lengthE
+    void $ send $ putObject (BucketName b) (ObjectKey (p -/- textFromString key)) $
+      Hashed $ HashedStream sha len $ sourceFileBS file
+
diff --git a/src/Network/AWS/Wolf/SWF.hs b/src/Network/AWS/Wolf/SWF.hs
--- a/src/Network/AWS/Wolf/SWF.hs
+++ b/src/Network/AWS/Wolf/SWF.hs
@@ -18,7 +18,7 @@
 
 import Control.Monad.Trans.AWS
 import Data.Conduit
-import Data.Conduit.List        hiding (concatMap, map)
+import Data.Conduit.Combinators hiding (concatMap)
 import Network.AWS.SWF
 import Network.AWS.Wolf.Ctx
 import Network.AWS.Wolf.Prelude
@@ -45,9 +45,9 @@
   d      <- view cDomain <$> view ccConf
   tl     <- taskList <$> view awcQueue
   runResourceT $ runAmazonCtx $ do
-    pfdtrs <- paginate (pollForDecisionTask d tl) $$ consume
+    pfdtrs <- paginate (pollForDecisionTask d tl) $$ sinkList
     pure
-      ( join $ headMay $ map (view pfdtrsTaskToken) pfdtrs
+      ( join $ headMay $ view pfdtrsTaskToken <$> pfdtrs
       , reverse $ concatMap (view pfdtrsEvents) pfdtrs
       )
 
diff --git a/wolf.cabal b/wolf.cabal
--- a/wolf.cabal
+++ b/wolf.cabal
@@ -1,5 +1,5 @@
 name: wolf
-version: 0.3.34
+version: 0.3.35
 cabal-version: >=1.22
 build-type: Simple
 license: MIT
@@ -23,11 +23,15 @@
     build-depends:
         aeson >=0.11.3.0,
         amazonka >=1.4.3,
+        amazonka-core >=1.4.3,
+        amazonka-s3 >=1.4.3,
         amazonka-swf >=1.4.3,
         base >=4.8 && <5,
         bytestring >=0.10.6.0,
         conduit >=1.2.10,
+        conduit-combinators >=1.0.8.3,
         directory >=1.2.2.0,
+        filemanip >=0.3.6.3,
         filepath >=1.4.0.0,
         http-types >=0.9.1,
         lifted-async >=0.9.1.1,
@@ -46,6 +50,7 @@
         Network.AWS.Wolf.Decide
         Network.AWS.Wolf.File
         Network.AWS.Wolf.Prelude
+        Network.AWS.Wolf.S3
         Network.AWS.Wolf.SWF
         Network.AWS.Wolf.Types
         Network.AWS.Wolf.Types.Ctx