diff --git a/codex/blocktype.nim b/codex/blocktype.nim
index afd64061..52bb5432 100644
--- a/codex/blocktype.nim
+++ b/codex/blocktype.nim
@@ -44,7 +44,6 @@ type
     else:
       cid*: Cid
 
-
 proc `==`*(a, b: BlockAddress): bool =
   a.leaf == b.leaf and
     (
diff --git a/codex/codextypes.nim b/codex/codextypes.nim
index b2d63225..6202fdcd 100644
--- a/codex/codextypes.nim
+++ b/codex/codextypes.nim
@@ -39,7 +39,7 @@ const
   BlockCodec* = multiCodec("codex-block")
   SlotRootCodec* = multiCodec("codex-slot-root")
   SlotProvingRootCodec* = multiCodec("codex-proving-root")
-  CodexSlotCell* = multiCodec("codex-slot-cell")
+  CodexSlotCellCodec* = multiCodec("codex-slot-cell")
 
   CodexHashesCodecs* = [
     Sha256HashCodec,
@@ -53,7 +53,7 @@ const
     BlockCodec,
     SlotRootCodec,
     SlotProvingRootCodec,
-    CodexSlotCell,
+    CodexSlotCellCodec,
   ]
 
 proc initEmptyCidTable(): ?!Table[(CidVersion, MultiCodec, MultiCodec), Cid] =
diff --git a/codex/erasure/erasure.nim b/codex/erasure/erasure.nim
index cd10b53a..b6977145 100644
--- a/codex/erasure/erasure.nim
+++ b/codex/erasure/erasure.nim
@@ -72,11 +72,11 @@ type
     store*: BlockStore
 
   EncodingParams = object
-    ecK: int
-    ecM: int
-    rounded: int
-    steps: int
-    blocksCount: int
+    ecK: Natural
+    ecM: Natural
+    rounded: Natural
+    steps: Natural
+    blocksCount: Natural
 
 func indexToPos(steps, idx, step: int): int {.inline.} =
   ## Convert an index to a position in the encoded
@@ -112,7 +112,8 @@ proc getPendingBlocks(
       return await completedFut
     else:
       let (_, index) = await completedFut
-      raise newException(CatchableError, "Future for block id not found, tree cid: " & $manifest.treeCid & ", index: " & $index)
+      raise newException(CatchableError,
+        "Future for block id not found, tree cid: " & $manifest.treeCid & ", index: " & $index)
 
   Iter.new(genNext, isFinished)
 
@@ -120,10 +121,10 @@ proc prepareEncodingData(
   self: Erasure,
   manifest: Manifest,
   params: EncodingParams,
-  step: int,
+  step: Natural,
   data: ref seq[seq[byte]],
   cids: ref seq[Cid],
-  emptyBlock: seq[byte]): Future[?!int] {.async.} =
+  emptyBlock: seq[byte]): Future[?!Natural] {.async.} =
   ## Prepare data for encoding
   ##
 
@@ -157,16 +158,16 @@ proc prepareEncodingData(
       return failure(err)
     cids[idx] = emptyBlockCid
 
-  success(resolved)
+  success(resolved.Natural)
 
 proc prepareDecodingData(
   self: Erasure,
   encoded: Manifest,
-  step: int,
+  step: Natural,
   data: ref seq[seq[byte]],
   parityData: ref seq[seq[byte]],
   cids: ref seq[Cid],
-  emptyBlock: seq[byte]): Future[?!(int, int)] {.async.} =
+  emptyBlock: seq[byte]): Future[?!(Natural, Natural)] {.async.} =
   ## Prepare data for decoding
   ## `encoded`    - the encoded manifest
   ## `step`       - the current step
@@ -222,14 +223,18 @@ proc prepareDecodingData(
 
     resolved.inc
 
-  return success (dataPieces, parityPieces)
+  return success (dataPieces.Natural, parityPieces.Natural)
 
 proc init*(
   _: type EncodingParams,
   manifest: Manifest,
-  ecK: int, ecM: int): ?!EncodingParams =
+  ecK: Natural, ecM: Natural): ?!EncodingParams =
   if ecK > manifest.blocksCount:
-    return failure("Unable to encode manifest, not enough blocks, ecK = " & $ecK & ", blocksCount = " & $manifest.blocksCount)
+    return failure(
+      "Unable to encode manifest, not enough blocks, ecK = " &
+      $ecK &
+      ", blocksCount = " &
+      $manifest.blocksCount)
 
   let
     rounded = roundUp(manifest.blocksCount, ecK)
@@ -338,8 +343,8 @@ proc encodeData(
 proc encode*(
   self: Erasure,
   manifest: Manifest,
-  blocks: int,
-  parity: int): Future[?!Manifest] {.async.} =
+  blocks: Natural,
+  parity: Natural): Future[?!Manifest] {.async.} =
   ## Encode a manifest into one that is erasure protected.
   ##
   ## `manifest`   - the original manifest to be encoded
@@ -347,7 +352,7 @@ proc encode*(
   ## `parity`     - the number of parity blocks to generate - M
   ##
 
-  without params =? EncodingParams.init(manifest, blocks, parity), err:
+  without params =? EncodingParams.init(manifest, blocks.int, parity.int), err:
     return failure(err)
 
   without encodedManifest =? await self.encodeData(manifest, params), err:
@@ -373,7 +378,7 @@ proc decode*(
 
   var
     cids = seq[Cid].new()
-    recoveredIndices = newSeq[int]()
+    recoveredIndices = newSeq[Natural]()
     decoder = self.decoderProvider(encoded.blockSize.int, encoded.ecK, encoded.ecM)
     emptyBlock = newSeq[byte](encoded.blockSize.int)
 
@@ -443,7 +448,7 @@ proc decode*(
 
   let idxIter = Iter
     .fromItems(recoveredIndices)
-    .filter((i: int) => i < tree.leavesCount)
+    .filter((i: Natural) => i < tree.leavesCount)
 
   if err =? (await self.store.putSomeProofs(tree, idxIter)).errorOption:
       return failure(err)
diff --git a/codex/errors.nim b/codex/errors.nim
index ff2789b9..9947d4b7 100644
--- a/codex/errors.nim
+++ b/codex/errors.nim
@@ -31,7 +31,8 @@ template mapFailure*[T, V, E](
 template mapFailure*[T, V](exp: Result[T, V]): Result[T, ref CatchableError] =
   mapFailure(exp, CodexError)
 
-template toResult*[T](exp: Option[T]): Result[T, ref CatchableError] =
+# TODO: using a template here, causes bad codegen
+func toFailure*[T](exp: Option[T]): Result[T, ref CatchableError] {.inline.} =
   if exp.isSome:
     success exp.get
   else:
diff --git a/codex/manifest/coders.nim b/codex/manifest/coders.nim
index 21069273..aef9d452 100644
--- a/codex/manifest/coders.nim
+++ b/codex/manifest/coders.nim
@@ -39,7 +39,7 @@ proc encode*(manifest: Manifest): ?!seq[byte] =
   #
   # ```protobuf
   #   Message VerificationInfo {
-  #     bytes verificationRoot = 1;            # Decimal encoded field-element
+  #     bytes verifyRoot = 1;             # Decimal encoded field-element
   #     repeated bytes slotRoots = 2;     # Decimal encoded field-elements
   #   }
   #   Message ErasureInfo {
@@ -78,7 +78,7 @@ proc encode*(manifest: Manifest): ?!seq[byte] =
 
     if manifest.verifiable:
       var verificationInfo = initProtoBuffer()
-      verificationInfo.write(1, manifest.verificationRoot.data.buffer)
+      verificationInfo.write(1, manifest.verifyRoot.data.buffer)
       for slotRoot in manifest.slotRoots:
         verificationInfo.write(2, slotRoot.data.buffer)
       erasureInfo.write(5, verificationInfo)
@@ -109,7 +109,7 @@ proc decode*(_: type Manifest, data: openArray[byte]): ?!Manifest =
     blockSize: uint32
     originalDatasetSize: uint32
     ecK, ecM: uint32
-    verificationRoot: seq[byte]
+    verifyRoot: seq[byte]
     slotRoots: seq[seq[byte]]
 
   # Decode `Header` message
@@ -158,8 +158,8 @@ proc decode*(_: type Manifest, data: openArray[byte]): ?!Manifest =
 
     verifiable = pbVerificationInfo.buffer.len > 0
     if verifiable:
-      if pbVerificationInfo.getField(1, verificationRoot).isErr:
-        return failure("Unable to decode `verificationRoot` from manifest!")
+      if pbVerificationInfo.getField(1, verifyRoot).isErr:
+        return failure("Unable to decode `verifyRoot` from manifest!")
 
       if pbVerificationInfo.getRequiredRepeatedField(2, slotRoots).isErr:
         return failure("Unable to decode `slotRoots` from manifest!")
@@ -193,12 +193,12 @@ proc decode*(_: type Manifest, data: openArray[byte]): ?!Manifest =
 
   if verifiable:
     let
-      verificationRootCid = ? Cid.init(verificationRoot).mapFailure
+      verifyRootCid = ? Cid.init(verifyRoot).mapFailure
       slotRootCids = slotRoots.mapIt(? Cid.init(it).mapFailure)
 
     return Manifest.new(
       manifest = self,
-      verificationRoot = verificationRootCid,
+      verifyRoot = verifyRootCid,
       slotRoots = slotRootCids
     )
 
diff --git a/codex/manifest/manifest.nim b/codex/manifest/manifest.nim
index 525d4f0e..a3dbd7cc 100644
--- a/codex/manifest/manifest.nim
+++ b/codex/manifest/manifest.nim
@@ -39,8 +39,8 @@ type
       originalDatasetSize: NBytes
       case verifiable {.serialize.}: bool   # Verifiable datasets can be used to generate storage proofs
       of true:
-        verificationRoot: Cid
-        slotRoots: seq[Cid]
+        verifyRoot: Cid                     # Root of the top level merkle tree built from slot roots
+        slotRoots: seq[Cid]                 # Individual slot root built from the original dataset blocks
       else:
         discard
     else:
@@ -92,8 +92,8 @@ proc blocksCount*(self: Manifest): int =
 proc verifiable*(self: Manifest): bool =
   self.verifiable
 
-proc verificationRoot*(self: Manifest): Cid =
-  self.verificationRoot
+proc verifyRoot*(self: Manifest): Cid =
+  self.verifyRoot
 
 proc slotRoots*(self: Manifest): seq[Cid] =
   self.slotRoots
@@ -103,6 +103,7 @@ proc numSlots*(self: Manifest): int =
     0
   else:
     self.ecK + self.ecM
+
 ############################################################
 # Operations on block list
 ############################################################
@@ -159,7 +160,7 @@ proc `==`*(a, b: Manifest): bool =
       (a.originalDatasetSize == b.originalDatasetSize) and
       (a.verifiable == b.verifiable) and
         (if a.verifiable:
-          (a.verificationRoot == b.verificationRoot) and
+          (a.verifyRoot == b.verifyRoot) and
           (a.slotRoots == b.slotRoots)
         else:
           true)
@@ -181,7 +182,7 @@ proc `$`*(self: Manifest): string =
       ", originalDatasetSize: " & $self.originalDatasetSize &
       ", verifiable: " & $self.verifiable &
       (if self.verifiable:
-        ", verificationRoot: " & $self.verificationRoot &
+        ", verifyRoot: " & $self.verifyRoot &
         ", slotRoots: " & $self.slotRoots
       else:
         "")
@@ -287,15 +288,21 @@ proc new*(
 proc new*(
   T: type Manifest,
   manifest: Manifest,
-  verificationRoot: Cid,
-  slotRoots: seq[Cid]): ?!Manifest =
+  verifyRoot: Cid,
+  slotRoots: openArray[Cid]): ?!Manifest =
   ## Create a verifiable dataset from an
   ## protected one
   ##
-  if not manifest.protected:
-    return failure newException(CodexError, "Can create verifiable manifest only from protected manifest.")
 
-  success(Manifest(
+  if not manifest.protected:
+    return failure newException(
+      CodexError, "Can create verifiable manifest only from protected manifest.")
+
+  if slotRoots.len != manifest.numSlots:
+    return failure newException(
+      CodexError, "Wrong number of slot roots.")
+
+  success Manifest(
     treeCid: manifest.treeCid,
     datasetSize: manifest.datasetSize,
     version: manifest.version,
@@ -308,5 +315,5 @@ proc new*(
     originalTreeCid: manifest.treeCid,
     originalDatasetSize: manifest.originalDatasetSize,
     verifiable: true,
-    verificationRoot: verificationRoot,
-    slotRoots: slotRoots))
+    verifyRoot: verifyRoot,
+    slotRoots: @slotRoots)
diff --git a/codex/merkletree.nim b/codex/merkletree.nim
index d7f6b1d7..bf5e3630 100644
--- a/codex/merkletree.nim
+++ b/codex/merkletree.nim
@@ -3,3 +3,8 @@ import ./merkletree/codex
 import ./merkletree/poseidon2
 
 export codex, poseidon2, merkletree
+
+type
+  SomeMerkleTree* = ByteTree | CodexTree | Poseidon2Tree
+  SomeMerkleProof* = ByteProof | CodexProof | Poseidon2Proof
+  SomeMerkleHash* = ByteHash | Poseidon2Hash
diff --git a/codex/merkletree/codex/codex.nim b/codex/merkletree/codex/codex.nim
index ea9790d0..49439eb3 100644
--- a/codex/merkletree/codex/codex.nim
+++ b/codex/merkletree/codex/codex.nim
@@ -23,6 +23,8 @@ import ../../rng
 import ../../errors
 import ../../blocktype
 
+from ../../utils/digest import digestBytes
+
 import ../merkletree
 
 export merkletree
@@ -62,12 +64,6 @@ func digestSize*(self: (CodexTree or CodexProof)): int =
 
   self.mhash.size
 
-func digestBytes*(mhash: MultiHash): seq[byte] =
-  ## Extract hash digestBytes
-  ##
-
-  mhash.data.buffer[mhash.dpos..<mhash.dpos + mhash.size]
-
 func getProof*(self: CodexTree, index: int): ?!CodexProof =
   var
     proof = CodexProof(mcodec: self.mcodec)
diff --git a/codex/node.nim b/codex/node.nim
index 81fee013..16d10821 100644
--- a/codex/node.nim
+++ b/codex/node.nim
@@ -16,6 +16,7 @@ import pkg/questionable
 import pkg/questionable/results
 import pkg/chronicles
 import pkg/chronos
+import pkg/poseidon2
 
 import pkg/libp2p/[switch, multicodec, multihash]
 import pkg/libp2p/stream/bufferstream
@@ -25,6 +26,7 @@ import pkg/libp2p/routing_record
 import pkg/libp2p/signed_envelope
 
 import ./chunker
+import ./slots
 import ./clock
 import ./blocktype as bt
 import ./manifest
@@ -38,6 +40,7 @@ import ./contracts
 import ./node/batch
 import ./utils
 import ./errors
+import ./merkletree
 
 export batch
 
@@ -56,17 +59,47 @@ type
     validator: ?ValidatorInteractions
 
   CodexNodeRef* = ref object
-    switch*: Switch
-    networkId*: PeerId
-    blockStore*: BlockStore
-    engine*: BlockExcEngine
-    erasure*: Erasure
-    discovery*: Discovery
+    switch: Switch
+    networkId: PeerId
+    blockStore: BlockStore
+    engine: BlockExcEngine
+    erasure: Erasure
+    discovery: Discovery
     contracts*: Contracts
     clock*: Clock
 
   OnManifest* = proc(cid: Cid, manifest: Manifest): void {.gcsafe, closure.}
 
+func switch*(self: CodexNodeRef): Switch =
+  return self.switch
+
+func blockStore*(self: CodexNodeRef): BlockStore =
+  return self.blockStore
+
+func engine*(self: CodexNodeRef): BlockExcEngine =
+  return self.engine
+
+func erasure*(self: CodexNodeRef): Erasure =
+  return self.erasure
+
+func discovery*(self: CodexNodeRef): Discovery =
+  return self.discovery
+
+proc storeManifest*(self: CodexNodeRef, manifest: Manifest): Future[?!bt.Block] {.async.} =
+  without encodedVerifiable =? manifest.encode(), err:
+    trace "Unable to encode manifest"
+    return failure(err)
+
+  without blk =? bt.Block.new(data = encodedVerifiable, codec = ManifestCodec), error:
+    trace "Unable to create block from manifest"
+    return failure(error)
+
+  if err =? (await self.blockStore.putBlock(blk)).errorOption:
+    trace "Unable to store manifest block", cid = blk.cid, err = err.msg
+    return failure(err)
+
+  success blk
+
 proc findPeer*(
   node: CodexNodeRef,
   peerId: PeerId): Future[?PeerRecord] {.async.} =
@@ -234,7 +267,6 @@ proc store*(
       if err =? (await self.blockStore.putBlock(blk)).errorOption:
         trace "Unable to store block", cid = blk.cid, err = err.msg
         return failure(&"Unable to store block {blk.cid}")
-
   except CancelledError as exc:
     raise exc
   except CatchableError as exc:
@@ -261,21 +293,11 @@ proc store*(
     datasetSize = NBytes(chunker.offset),
     version = CIDv1,
     hcodec = hcodec,
-    codec = dataCodec
-  )
-  # Generate manifest
-  without data =? manifest.encode(), err:
-    return failure(
-      newException(CodexError, "Error encoding manifest: " & err.msg))
+    codec = dataCodec)
 
-  # Store as a dag-pb block
-  without manifestBlk =? bt.Block.new(data = data, codec = ManifestCodec):
-    trace "Unable to init block from manifest data!"
-    return failure("Unable to init block from manifest data!")
-
-  if isErr (await self.blockStore.putBlock(manifestBlk)):
-    trace "Unable to store manifest", cid = manifestBlk.cid
-    return failure("Unable to store manifest " & $manifestBlk.cid)
+  without manifestBlk =? await self.storeManifest(manifest), err:
+    trace "Unable to store manifest"
+    return failure(err)
 
   info "Stored data", manifestCid = manifestBlk.cid,
                       treeCid = treeCid,
@@ -305,6 +327,91 @@ proc iterateManifests*(node: CodexNodeRef, onManifest: OnManifest) {.async.} =
 
       onManifest(cid, manifest)
 
+proc setupRequest(
+  self: CodexNodeRef,
+  cid: Cid,
+  duration: UInt256,
+  proofProbability: UInt256,
+  nodes: uint,
+  tolerance: uint,
+  reward: UInt256,
+  collateral: UInt256,
+  expiry:  UInt256): Future[?!StorageRequest] {.async.} =
+  ## Setup slots for a given dataset
+  ##
+
+  let
+    ecK = nodes - tolerance
+    ecM = tolerance
+
+  logScope:
+    cid               = cid
+    duration          = duration
+    nodes             = nodes
+    tolerance         = tolerance
+    reward            = reward
+    proofProbability  = proofProbability
+    collateral        = collateral
+    expiry            = expiry
+    ecK               = ecK
+    ecM               = ecM
+
+  trace "Setting up slots"
+
+  without manifest =? await self.fetchManifest(cid), error:
+    trace "Unable to fetch manifest for cid"
+    return failure error
+
+  # Erasure code the dataset according to provided parameters
+  without encoded =? (await self.erasure.encode(manifest, ecK, ecM)), error:
+    trace "Unable to erasure code dataset"
+    return failure(error)
+
+  without builder =? SlotsBuilder.new(self.blockStore, encoded), err:
+    trace "Unable to create slot builder"
+    return failure(err)
+
+  without verifiable =? (await builder.buildManifest()), err:
+    trace "Unable to build verifiable manifest"
+    return failure(err)
+
+  without manifestBlk =? await self.storeManifest(verifiable), err:
+    trace "Unable to store verifiable manifest"
+    return failure(err)
+
+  let
+    verifyRoot =
+      if builder.verifyRoot.isNone:
+          return failure("No slots root")
+        else:
+          builder.verifyRoot.get.toBytes
+
+    slotRoots =
+      if builder.slotRoots.len <= 0:
+          return failure("Slots are empty")
+        else:
+          builder.slotRoots.mapIt( it.toBytes )
+
+    request = StorageRequest(
+      ask: StorageAsk(
+        slots: verifiable.numSlots.uint64,
+        slotSize: builder.slotBytes.uint.u256,
+        duration: duration,
+        proofProbability: proofProbability,
+        reward: reward,
+        collateral: collateral,
+        maxSlotLoss: tolerance
+      ),
+      content: StorageContent(
+        cid: $manifestBlk.cid, # TODO: why string?
+        merkleRoot: verifyRoot
+      ),
+      expiry: expiry
+    )
+
+  trace "Request created", request = $request
+  success request
+
 proc requestStorage*(
   self: CodexNodeRef,
   cid: Cid,
@@ -318,64 +425,38 @@ proc requestStorage*(
   ## Initiate a request for storage sequence, this might
   ## be a multistep procedure.
   ##
-  ## Roughly the flow is as follows:
-  ## - Get the original cid from the store (should have already been uploaded)
-  ## - Erasure code it according to the nodes and tolerance parameters
-  ## - Run the PoR setup on the erasure dataset
-  ## - Call into the marketplace and purchasing contracts
-  ##
-  trace "Received a request for storage!", cid, duration, nodes, tolerance, reward, proofProbability, collateral, expiry
+
+  logScope:
+    cid               = cid
+    duration          = duration
+    nodes             = nodes
+    tolerance         = tolerance
+    reward            = reward
+    proofProbability  = proofProbability
+    collateral        = collateral
+    expiry            = expiry
+
+  trace "Received a request for storage!"
 
   without contracts =? self.contracts.client:
     trace "Purchasing not available"
     return failure "Purchasing not available"
 
-  without manifest =? await self.fetchManifest(cid), error:
-    trace "Unable to fetch manifest for cid", cid
-    raise error
-
-  # Erasure code the dataset according to provided parameters
-  without encoded =? (await self.erasure.encode(manifest, nodes.int, tolerance.int)), error:
-    trace "Unable to erasure code dataset", cid
-    return failure(error)
-
-  without encodedData =? encoded.encode(), error:
-    trace "Unable to encode protected manifest"
-    return failure(error)
-
-  without encodedBlk =? bt.Block.new(data = encodedData, codec = ManifestCodec), error:
-    trace "Unable to create block from encoded manifest"
-    return failure(error)
-
-  if isErr (await self.blockStore.putBlock(encodedBlk)):
-    trace "Unable to store encoded manifest block", cid = encodedBlk.cid
-    return failure("Unable to store encoded manifest block")
-
-  let request = StorageRequest(
-    ask: StorageAsk(
-      slots: nodes + tolerance,
-      # TODO: Specify slot-specific size (as below) once dispersal is
-      # implemented. The current implementation downloads the entire dataset, so
-      # it is currently set to be the size of the entire dataset. This is
-      # because the slotSize is used to determine the amount of bytes to reserve
-      # in a Reservations
-      # TODO: slotSize: (encoded.blockSize.int * encoded.steps).u256,
-      slotSize: (encoded.blockSize.int * encoded.blocksCount).u256,
-      duration: duration,
-      proofProbability: proofProbability,
-      reward: reward,
-      collateral: collateral,
-      maxSlotLoss: tolerance
-    ),
-    content: StorageContent(
-      cid: $encodedBlk.cid,
-      merkleRoot: array[32, byte].default # TODO: add merkle root for storage proofs
-    ),
-    expiry: expiry
-  )
+  without request =?
+    (await self.setupRequest(
+      cid,
+      duration,
+      proofProbability,
+      nodes,
+      tolerance,
+      reward,
+      collateral,
+      expiry)), err:
+    trace "Unable to setup request"
+    return failure err
 
   let purchase = await contracts.purchasing.purchase(request)
-  return success purchase.id
+  success purchase.id
 
 proc new*(
   T: type CodexNodeRef,
diff --git a/codex/purchasing/purchase.nim b/codex/purchasing/purchase.nim
index add60a2f..d616e492 100644
--- a/codex/purchasing/purchase.nim
+++ b/codex/purchasing/purchase.nim
@@ -33,7 +33,8 @@ func new*(
   ## create a new instance of a Purchase
   ##
   var purchase = Purchase.new()
-  purchase.future = Future[void].new()
+  {.cast(noSideEffect).}:
+    purchase.future = newFuture[void]()
   purchase.requestId = requestId
   purchase.market = market
   purchase.clock = clock
diff --git a/codex/rest/api.nim b/codex/rest/api.nim
index 2f1b192c..69254ee9 100644
--- a/codex/rest/api.nim
+++ b/codex/rest/api.nim
@@ -300,8 +300,8 @@ proc initPurchasingApi(node: CodexNodeRef, router: var RestRouter) =
       ## proofProbability - how often storage proofs are required
       ## reward           - the maximum amount of tokens paid per second per slot to hosts the client is willing to pay
       ## expiry           - timestamp, in seconds, when the request expires if the Request does not find requested amount of nodes to host the data
-      ## nodes            - minimal number of nodes the content should be stored on
-      ## tolerance        - allowed number of nodes that can be lost before pronouncing the content lost
+      ## nodes            - number of nodes the content should be stored on
+      ## tolerance        - allowed number of nodes that can be lost before content is lost
       ## colateral        - requested collateral from hosts when they fill slot
 
       try:
@@ -319,6 +319,9 @@ proc initPurchasingApi(node: CodexNodeRef, router: var RestRouter) =
         let nodes = params.nodes |? 1
         let tolerance = params.tolerance |? 0
 
+        if (nodes - tolerance) < 1:
+          return RestApiResponse.error(Http400, "Tolerance cannot be greater or equal than nodes (nodes - tolerance)")
+
         without expiry =? params.expiry:
           return RestApiResponse.error(Http400, "Expiry required")
 
diff --git a/codex/slots.nim b/codex/slots.nim
new file mode 100644
index 00000000..a34949f3
--- /dev/null
+++ b/codex/slots.nim
@@ -0,0 +1,3 @@
+import ./slots/builder
+
+export builder
diff --git a/codex/slots/slotbuilder.nim b/codex/slots/builder.nim
similarity index 57%
rename from codex/slots/slotbuilder.nim
rename to codex/slots/builder.nim
index a3b24b35..177c17c4 100644
--- a/codex/slots/slotbuilder.nim
+++ b/codex/slots/builder.nim
@@ -19,6 +19,7 @@ import pkg/chronicles
 import pkg/questionable/results
 import pkg/poseidon2
 import pkg/poseidon2/io
+import pkg/constantine/math/arithmetic/finite_fields
 
 import ../indexingstrategy
 import ../merkletree
@@ -26,51 +27,90 @@ import ../stores
 import ../manifest
 import ../utils
 import ../utils/digest
+import ../utils/poseidon2digest
 
 const
   # TODO: Unified with the CellSize specified in branch "data-sampler"
-  # Number of bytes in a cell. A cell is the smallest unit of data used
   # in the proving circuit.
   CellSize* = 2048
 
+  DefaultEmptyBlock* = newSeq[byte](DefaultBlockSize.int)
+  DefaultEmptyCell* = newSeq[byte](DefaultCellSize.int)
+
 type
-  SlotBuilder* = object of RootObj
+  # TODO: should be a generic type that
+  # supports all merkle trees
+  SlotsBuilder* = ref object of RootObj
     store: BlockStore
     manifest: Manifest
     strategy: IndexingStrategy
     cellSize: int
+    blockEmptyDigest: Poseidon2Hash
     blockPadBytes: seq[byte]
     slotsPadLeafs: seq[Poseidon2Hash]
     rootsPadLeafs: seq[Poseidon2Hash]
+    slotRoots: seq[Poseidon2Hash]
+    verifyRoot: ?Poseidon2Hash
 
-func numBlockPadBytes*(self: SlotBuilder): Natural =
+func slotRoots*(self: SlotsBuilder): seq[Poseidon2Hash] {.inline.} =
+  ## Returns the slot roots.
+  ##
+
+  self.slotRoots
+
+func verifyRoot*(self: SlotsBuilder): ?Poseidon2Hash {.inline.} =
+  ## Returns the slots root (verification root).
+  ##
+
+  self.verifyRoot
+
+func nextPowerOfTwoPad*(a: int): int =
+  ## Returns the difference between the original
+  ## value and the next power of two.
+  ##
+
+  nextPowerOfTwo(a) - a
+
+func numBlockPadBytes*(self: SlotsBuilder): Natural =
   ## Number of padding bytes required for a pow2
   ## merkle tree for each block.
   ##
 
   self.blockPadBytes.len
 
-func numSlotsPadLeafs*(self: SlotBuilder): Natural =
+func numSlotsPadLeafs*(self: SlotsBuilder): Natural =
   ## Number of padding field elements required for a pow2
   ## merkle tree for each slot.
   ##
 
   self.slotsPadLeafs.len
 
-func numRootsPadLeafs*(self: SlotBuilder): Natural =
+func numRootsPadLeafs*(self: SlotsBuilder): Natural =
   ## Number of padding field elements required for a pow2
   ## merkle tree for the slot roots.
   ##
 
   self.rootsPadLeafs.len
 
-func numSlotBlocks*(self: SlotBuilder): Natural =
+func numSlots*(self: SlotsBuilder): Natural =
+  ## Number of slots.
+  ##
+
+  self.manifest.numSlots
+
+func numSlotBlocks*(self: SlotsBuilder): Natural =
   ## Number of blocks per slot.
   ##
 
   self.manifest.blocksCount div self.manifest.numSlots
 
-func numBlockRoots*(self: SlotBuilder): Natural =
+func slotBytes*(self: SlotsBuilder): NBytes =
+  ## Number of bytes per slot.
+  ##
+
+  (self.manifest.blockSize.int * self.numSlotBlocks).NBytes
+
+func numBlockCells*(self: SlotsBuilder): Natural =
   ## Number of cells per block.
   ##
 
@@ -79,7 +119,7 @@ func numBlockRoots*(self: SlotBuilder): Natural =
 func toCellCid*(cell: Poseidon2Hash): ?!Cid =
   let
     cellMhash = ? MultiHash.init(Pos2Bn128MrklCodec, cell.toBytes).mapFailure
-    cellCid = ? Cid.init(CIDv1, CodexSlotCell, cellMhash).mapFailure
+    cellCid = ? Cid.init(CIDv1, CodexSlotCellCodec, cellMhash).mapFailure
 
   success cellCid
 
@@ -90,16 +130,16 @@ func toSlotCid*(root: Poseidon2Hash): ?!Cid =
 
   success treeCid
 
-func toProvingCid*(root: Poseidon2Hash): ?!Cid =
+func toSlotCids*(slotRoots: openArray[Poseidon2Hash]): ?!seq[Cid] =
+  success slotRoots.mapIt( ? it.toSlotCid )
+
+func toSlotsRootsCid*(root: Poseidon2Hash): ?!Cid =
   let
     mhash = ? MultiHash.init($multiCodec("identity"), root.toBytes).mapFailure
     treeCid = ? Cid.init(CIDv1, SlotProvingRootCodec, mhash).mapFailure
 
   success treeCid
 
-func mapToSlotCids*(slotRoots: seq[Poseidon2Hash]): ?!seq[Cid] =
-  success slotRoots.mapIt( ? it.toSlotCid )
-
 func toEncodableProof*(
   proof: Poseidon2Proof): ?!CodexProof =
 
@@ -120,13 +160,13 @@ func toVerifiableProof*(
       index: proof.index,
       nleaves: proof.nleaves,
       path: proof.path.mapIt(
-        ? Poseidon2Hash.fromBytes(it.toArray32).toResult
+        ? Poseidon2Hash.fromBytes(it.toArray32).toFailure
       ))
 
   success verifiableProof
 
 proc getCellHashes*(
-  self: SlotBuilder,
+  self: SlotsBuilder,
   slotIndex: int): Future[?!seq[Poseidon2Hash]] {.async.} =
 
   let
@@ -150,16 +190,19 @@ proc getCellHashes*(
           error "Failed to get block CID for tree at index"
           return failure(err)
 
-        without digest =? Poseidon2Tree.digest(blk.data & self.blockPadBytes, self.cellSize), err:
-          error "Failed to create digest for block"
-          return failure(err)
+        if blk.isEmpty:
+          self.blockEmptyDigest
+        else:
+          without digest =? Poseidon2Tree.digest(blk.data & self.blockPadBytes, self.cellSize), err:
+            error "Failed to create digest for block"
+            return failure(err)
 
-        digest
+          digest
 
   success hashes
 
 proc buildSlotTree*(
-  self: SlotBuilder,
+  self: SlotsBuilder,
   slotIndex: int): Future[?!Poseidon2Tree] {.async.} =
   without cellHashes =? (await self.getCellHashes(slotIndex)), err:
     error "Failed to select slot blocks", err = err.msg
@@ -168,11 +211,17 @@ proc buildSlotTree*(
   Poseidon2Tree.init(cellHashes & self.slotsPadLeafs)
 
 proc buildSlot*(
-  self: SlotBuilder,
+  self: SlotsBuilder,
   slotIndex: int): Future[?!Poseidon2Hash] {.async.} =
   ## Build a slot tree and store it in the block store.
   ##
 
+  logScope:
+    cid         = self.manifest.treeCid
+    slotIndex   = slotIndex
+
+  trace "Building slot tree"
+
   without tree =? (await self.buildSlotTree(slotIndex)) and
     treeCid =? tree.root.?toSlotCid, err:
     error "Failed to build slot tree", err = err.msg
@@ -196,54 +245,65 @@ proc buildSlot*(
 
   tree.root()
 
-proc buildSlots*(self: SlotBuilder): Future[?!seq[Poseidon2Hash]] {.async.} =
-  let
-    slotRoots: seq[Poseidon2Hash] = collect(newSeq):
+func buildRootsTree*(
+  self: SlotsBuilder,
+  slotRoots: openArray[Poseidon2Hash]): ?!Poseidon2Tree =
+  Poseidon2Tree.init(@slotRoots & self.rootsPadLeafs)
+
+proc buildSlots*(self: SlotsBuilder): Future[?!void] {.async.} =
+  ## Build all slot trees and store them in the block store.
+  ##
+
+  logScope:
+    cid         = self.manifest.treeCid
+    blockCount  = self.manifest.blocksCount
+
+  trace "Building slots"
+
+  if self.slotRoots.len == 0:
+    self.slotRoots = collect(newSeq):
       for i in 0..<self.manifest.numSlots:
-        without root =? (await self.buildSlot(i)), err:
+        without slotRoot =? (await self.buildSlot(i)), err:
           error "Failed to build slot", err = err.msg, index = i
           return failure(err)
-        root
+        slotRoot
 
-  success slotRoots
+  without root =? self.buildRootsTree(self.slotRoots).?root(), err:
+    error "Failed to build slot roots tree", err = err.msg
+    return failure(err)
 
-func buildRootsTree*(
-  self: SlotBuilder,
-  slotRoots: seq[Poseidon2Hash]): ?!Poseidon2Tree =
-  Poseidon2Tree.init(slotRoots & self.rootsPadLeafs)
+  if self.verifyRoot.isSome and self.verifyRoot.get != root: # TODO: `!=` doesn't work for SecretBool
+      return failure "Existing slots root doesn't match reconstructed root."
+  else:
+    self.verifyRoot = some root
 
-proc buildManifest*(self: SlotBuilder): Future[?!Manifest] {.async.} =
+  success()
 
-  without slotRoots =? await self.buildSlots(), err:
+proc buildManifest*(self: SlotsBuilder): Future[?!Manifest] {.async.} =
+  if err =? (await self.buildSlots()).errorOption:
     error "Failed to build slot roots", err = err.msg
     return failure(err)
 
-  without provingRootCid =? self.buildRootsTree(slotRoots).?root.?toProvingCid, err:
-    error "Failed to build proving tree", err = err.msg
-    return failure(err)
-
-  without rootCids =? slotRoots.mapToSlotCids(), err:
+  without rootCids =? self.slotRoots.toSlotCids(), err:
     error "Failed to map slot roots to CIDs", err = err.msg
     return failure(err)
 
-  Manifest.new(self.manifest, provingRootCid, rootCids)
+  without rootProvingCidRes =? self.verifyRoot.?toSlotsRootsCid() and
+    rootProvingCid =? rootProvingCidRes, err: # TODO: why doesn't `.?` unpack the result?
+    error "Failed to map slot roots to CIDs", err = err.msg
+    return failure(err)
 
-func nextPowerOfTwoPad*(a: int): int =
-  ## Returns the difference between the original
-  ## value and the next power of two.
-  ##
-
-  nextPowerOfTwo(a) - a
+  Manifest.new(self.manifest, rootProvingCid, rootCids)
 
 proc new*(
-  T: type SlotBuilder,
+  T: type SlotsBuilder,
   store: BlockStore,
   manifest: Manifest,
-  strategy: IndexingStrategy = nil,
-  cellSize = CellSize): ?!SlotBuilder =
+  strategy: ?IndexingStrategy = none IndexingStrategy,
+  cellSize = CellSize): ?!SlotsBuilder =
 
   if not manifest.protected:
-    return failure("Can only create SlotBuilder using protected manifests.")
+    return failure("Can only create SlotsBuilder using protected manifests.")
 
   if (manifest.blocksCount mod manifest.numSlots) != 0:
     return failure("Number of blocks must be divisable by number of slots.")
@@ -252,11 +312,11 @@ proc new*(
     return failure("Block size must be divisable by cell size.")
 
   let
-    strategy = if strategy == nil:
+    strategy = if strategy.isNone:
       SteppedIndexingStrategy.new(
         0, manifest.blocksCount - 1, manifest.numSlots)
       else:
-        strategy
+        strategy.get
 
     # all trees have to be padded to power of two
     numBlockCells = manifest.blockSize.int div cellSize                       # number of cells per block
@@ -264,12 +324,41 @@ proc new*(
     numSlotLeafs = (manifest.blocksCount div manifest.numSlots)
     slotsPadLeafs = newSeqWith(numSlotLeafs.nextPowerOfTwoPad, Poseidon2Zero) # power of two padding for block roots
     rootsPadLeafs = newSeqWith(manifest.numSlots.nextPowerOfTwoPad, Poseidon2Zero)
+    blockEmptyDigest = ? Poseidon2Tree.digest(DefaultEmptyBlock & blockPadBytes, CellSize)
 
-  success SlotBuilder(
+  var self = SlotsBuilder(
     store: store,
     manifest: manifest,
     strategy: strategy,
     cellSize: cellSize,
     blockPadBytes: blockPadBytes,
     slotsPadLeafs: slotsPadLeafs,
-    rootsPadLeafs: rootsPadLeafs)
+    rootsPadLeafs: rootsPadLeafs,
+    blockEmptyDigest: blockEmptyDigest)
+
+  if manifest.verifiable:
+    if manifest.slotRoots.len == 0 or manifest.slotRoots.len != manifest.numSlots:
+      return failure "Manifest is verifiable but slot r"
+
+    let
+      slotRoot = ? Poseidon2Hash.fromBytes(
+        ( ? manifest.verifyRoot.mhash.mapFailure ).digestBytes.toArray32
+      ).toFailure
+
+      slotRoots = manifest.slotRoots.mapIt(
+        ? Poseidon2Hash.fromBytes(
+          ( ? it.mhash.mapFailure ).digestBytes.toArray32
+        ).toFailure
+      )
+
+    without root =? self.buildRootsTree(slotRoots).?root(), err:
+      error "Failed to build slot roots tree", err = err.msg
+      return failure(err)
+
+    if slotRoot != root:
+      return failure "Existing slots root doesn't match reconstructed root."
+
+    self.slotRoots = slotRoots
+    self.verifyRoot = some slotRoot
+
+  success self
diff --git a/codex/utils/digest.nim b/codex/utils/digest.nim
index a89c1659..4b3e68bf 100644
--- a/codex/utils/digest.nim
+++ b/codex/utils/digest.nim
@@ -1,53 +1,8 @@
-## Nim-Codex
-## Copyright (c) 2023 Status Research & Development GmbH
-## Licensed under either of
-##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
-##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
-## at your option.
-## This file may not be copied, modified, or distributed except according to
-## those terms.
 
-import pkg/poseidon2
-import pkg/poseidon2/io
-import pkg/questionable/results
-import pkg/libp2p/multihash
+from pkg/libp2p import MultiHash
 
-import ../merkletree
-
-func digestTree*(
-  _: type Poseidon2Tree,
-  bytes: openArray[byte], chunkSize: int): ?!Poseidon2Tree =
-  ## Hashes chunks of data with a sponge of rate 2, and combines the
-  ## resulting chunk hashes in a merkle root.
+func digestBytes*(mhash: MultiHash): seq[byte] =
+  ## Extract hash digestBytes
   ##
 
-  var index = 0
-  var leaves: seq[Poseidon2Hash]
-  while index < bytes.len:
-    let start = index
-    let finish = min(index + chunkSize, bytes.len)
-    let digest = Sponge.digest(bytes.toOpenArray(start, finish - 1), rate = 2)
-    leaves.add(digest)
-    index += chunkSize
-  return Poseidon2Tree.init(leaves)
-
-func digest*(
-  _: type Poseidon2Tree,
-  bytes: openArray[byte], chunkSize: int): ?!Poseidon2Hash =
-  ## Hashes chunks of data with a sponge of rate 2, and combines the
-  ## resulting chunk hashes in a merkle root.
-  ##
-
-  (? Poseidon2Tree.digestTree(bytes, chunkSize)).root
-
-func digestMhash*(
-  _: type Poseidon2Tree,
-  bytes: openArray[byte], chunkSize: int): ?!MultiHash =
-  ## Hashes chunks of data with a sponge of rate 2 and
-  ## returns the multihash of the root
-  ##
-
-  let
-    hash = ? Poseidon2Tree.digest(bytes, chunkSize)
-
-  ? MultiHash.init(Pos2Bn128MrklCodec, hash).mapFailure
+  mhash.data.buffer[mhash.dpos..<mhash.dpos + mhash.size]
diff --git a/codex/utils/poseidon2digest.nim b/codex/utils/poseidon2digest.nim
new file mode 100644
index 00000000..5ea8c671
--- /dev/null
+++ b/codex/utils/poseidon2digest.nim
@@ -0,0 +1,52 @@
+## Nim-Codex
+## Copyright (c) 2023 Status Research & Development GmbH
+## Licensed under either of
+##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+## at your option.
+## This file may not be copied, modified, or distributed except according to
+## those terms.
+
+import pkg/poseidon2
+import pkg/questionable/results
+import pkg/libp2p/multihash
+
+import ../merkletree
+
+func digestTree*(
+  _: type Poseidon2Tree,
+  bytes: openArray[byte], chunkSize: int): ?!Poseidon2Tree =
+  ## Hashes chunks of data with a sponge of rate 2, and combines the
+  ## resulting chunk hashes in a merkle root.
+  ##
+
+  var index = 0
+  var leaves: seq[Poseidon2Hash]
+  while index < bytes.len:
+    let start = index
+    let finish = min(index + chunkSize, bytes.len)
+    let digest = Sponge.digest(bytes.toOpenArray(start, finish - 1), rate = 2)
+    leaves.add(digest)
+    index += chunkSize
+  return Poseidon2Tree.init(leaves)
+
+func digest*(
+  _: type Poseidon2Tree,
+  bytes: openArray[byte], chunkSize: int): ?!Poseidon2Hash =
+  ## Hashes chunks of data with a sponge of rate 2, and combines the
+  ## resulting chunk hashes in a merkle root.
+  ##
+
+  (? Poseidon2Tree.digestTree(bytes, chunkSize)).root
+
+func digestMhash*(
+  _: type Poseidon2Tree,
+  bytes: openArray[byte], chunkSize: int): ?!MultiHash =
+  ## Hashes chunks of data with a sponge of rate 2 and
+  ## returns the multihash of the root
+  ##
+
+  let
+    hash = ? Poseidon2Tree.digest(bytes, chunkSize)
+
+  ? MultiHash.init(Pos2Bn128MrklCodec, hash).mapFailure
diff --git a/config.nims b/config.nims
index 06e6eff1..a00ce831 100644
--- a/config.nims
+++ b/config.nims
@@ -73,6 +73,7 @@ else:
 --define:nimTypeNames
 --styleCheck:usages
 --styleCheck:error
+--maxLoopIterationsVM:1000000000
 
 when (NimMajor, NimMinor) >= (1, 4):
   --warning:"ObservableStores:off"
diff --git a/tests/codex/merkletree/testcodextree.nim b/tests/codex/merkletree/testcodextree.nim
index ace612f5..3312309c 100644
--- a/tests/codex/merkletree/testcodextree.nim
+++ b/tests/codex/merkletree/testcodextree.nim
@@ -9,6 +9,7 @@ import pkg/libp2p
 
 import pkg/codex/codextypes
 import pkg/codex/merkletree
+import pkg/codex/utils/digest
 
 import ./helpers
 import ./generictreetests
diff --git a/tests/codex/merkletree/testmerkledigest.nim b/tests/codex/merkletree/testmerkledigest.nim
index 21945d2e..6ef40e4e 100644
--- a/tests/codex/merkletree/testmerkledigest.nim
+++ b/tests/codex/merkletree/testmerkledigest.nim
@@ -12,6 +12,7 @@ import pkg/questionable/results
 
 import pkg/codex/merkletree
 import pkg/codex/utils/digest
+import pkg/codex/utils/poseidon2digest
 
 import ./helpers
 
diff --git a/tests/codex/slotbuilder/testslotbuilder.nim b/tests/codex/slotbuilder/testslotbuilder.nim
index ac75a41c..8cb21d77 100644
--- a/tests/codex/slotbuilder/testslotbuilder.nim
+++ b/tests/codex/slotbuilder/testslotbuilder.nim
@@ -11,6 +11,7 @@ import pkg/codex/rng
 import pkg/codex/stores
 import pkg/codex/chunker
 import pkg/codex/merkletree
+import pkg/codex/manifest {.all.}
 import pkg/codex/utils
 import pkg/codex/utils/digest
 import pkg/datastore
@@ -23,7 +24,10 @@ import ../examples
 import ../merkletree/helpers
 
 import pkg/codex/indexingstrategy {.all.}
-import pkg/codex/slots/slotbuilder {.all.}
+import pkg/codex/slots {.all.}
+
+privateAccess(SlotsBuilder) # enable access to private fields
+privateAccess(Manifest) # enable access to private fields
 
 suite "Slot builder":
   let
@@ -57,7 +61,7 @@ suite "Slot builder":
     manifest: Manifest
     protectedManifest: Manifest
     expectedEmptyCid: Cid
-    slotBuilder: SlotBuilder
+    slotBuilder: SlotsBuilder
     chunker: Chunker
 
   proc createBlocks(): Future[void] {.async.} =
@@ -115,8 +119,6 @@ suite "Slot builder":
       protectedManifest.hcodec,
       protectedManifest.codec).tryGet()
 
-  privateAccess(SlotBuilder) # enable access to private fields
-
   setup:
     let
       repoDs = SQLiteDatastore.new(Memory).tryGet()
@@ -130,6 +132,9 @@ suite "Slot builder":
   teardown:
     await localStore.close()
 
+    # TODO: THIS IS A BUG IN asynctest, because it doesn't release the
+    #       objects after the test is done, so we need to do it manually
+    #
     # Need to reset all objects because otherwise they get
     # captured by the test runner closures, not good!
     reset(datasetBlocks)
@@ -148,8 +153,8 @@ suite "Slot builder":
         datasetSize = originalDatasetSize.NBytes)
 
     check:
-      SlotBuilder.new(localStore, unprotectedManifest, cellSize = cellSize)
-        .error.msg == "Can only create SlotBuilder using protected manifests."
+      SlotsBuilder.new(localStore, unprotectedManifest, cellSize = cellSize)
+        .error.msg == "Can only create SlotsBuilder using protected manifests."
 
   test "Number of blocks must be devisable by number of slots":
     let
@@ -164,7 +169,7 @@ suite "Slot builder":
         ecM = ecM)
 
     check:
-      SlotBuilder.new(localStore, mismatchManifest, cellSize = cellSize)
+      SlotsBuilder.new(localStore, mismatchManifest, cellSize = cellSize)
         .error.msg == "Number of blocks must be divisable by number of slots."
 
   test "Block size must be divisable by cell size":
@@ -180,11 +185,11 @@ suite "Slot builder":
         ecM = ecM)
 
     check:
-      SlotBuilder.new(localStore, mismatchManifest, cellSize = cellSize)
+      SlotsBuilder.new(localStore, mismatchManifest, cellSize = cellSize)
         .error.msg == "Block size must be divisable by cell size."
 
   test "Should build correct slot builder":
-    slotBuilder = SlotBuilder.new(
+    slotBuilder = SlotsBuilder.new(
       localStore,
       protectedManifest,
       cellSize = cellSize).tryGet()
@@ -197,7 +202,7 @@ suite "Slot builder":
   test "Should build slot hashes for all slots":
     let
       steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
-      slotBuilder = SlotBuilder.new(
+      slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
         cellSize = cellSize).tryGet()
@@ -220,7 +225,7 @@ suite "Slot builder":
   test "Should build slot trees for all slots":
     let
       steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
-      slotBuilder = SlotBuilder.new(
+      slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
         cellSize = cellSize).tryGet()
@@ -243,7 +248,7 @@ suite "Slot builder":
 
   test "Should persist trees for all slots":
     let
-      slotBuilder = SlotBuilder.new(
+      slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
         cellSize = cellSize).tryGet()
@@ -268,12 +273,13 @@ suite "Slot builder":
   test "Should build correct verification root":
     let
       steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
-      slotBuilder = SlotBuilder.new(
+      slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
         cellSize = cellSize).tryGet()
-      slotRoots = (await slotBuilder.buildSlots()).tryGet
 
+    (await slotBuilder.buildSlots()).tryGet
+    let
       slotsHashes = collect(newSeq):
         for i in 0 ..< numSlots:
           let
@@ -288,7 +294,7 @@ suite "Slot builder":
           Merkle.digest(slotHashes & slotsPadLeafs)
 
       expectedRoot = Merkle.digest(slotsHashes & rootsPadLeafs)
-      rootHash = slotBuilder.buildRootsTree(slotRoots).tryGet().root.tryGet()
+      rootHash = slotBuilder.buildRootsTree(slotBuilder.slotRoots).tryGet().root.tryGet()
 
     check:
       expectedRoot == rootHash
@@ -296,7 +302,7 @@ suite "Slot builder":
   test "Should build correct verification root manifest":
     let
       steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
-      slotBuilder = SlotBuilder.new(
+      slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
         cellSize = cellSize).tryGet()
@@ -316,9 +322,78 @@ suite "Slot builder":
 
       expectedRoot = Merkle.digest(slotsHashes & rootsPadLeafs)
       manifest = (await slotBuilder.buildManifest()).tryGet()
-      mhash = manifest.verificationRoot.mhash.tryGet()
+      mhash = manifest.verifyRoot.mhash.tryGet()
       mhashBytes = mhash.digestBytes
-      rootHash = Poseidon2Hash.fromBytes(mhashBytes.toArray32).toResult.tryGet()
+      rootHash = Poseidon2Hash.fromBytes(mhashBytes.toArray32).get
 
     check:
       expectedRoot == rootHash
+
+  test "Should not build from verifiable manifest with 0 slots":
+    var
+      slotBuilder = SlotsBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+      verifyManifest = (await slotBuilder.buildManifest()).tryGet()
+
+    verifyManifest.slotRoots = @[]
+    check SlotsBuilder.new(
+        localStore,
+        verifyManifest,
+        cellSize = cellSize).isErr
+
+  test "Should not build from verifiable manifest with incorrect number of slots":
+    var
+      slotBuilder = SlotsBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+      verifyManifest = (await slotBuilder.buildManifest()).tryGet()
+
+    verifyManifest.slotRoots.del(
+      verifyManifest.slotRoots.len - 1
+    )
+
+    check SlotsBuilder.new(
+        localStore,
+        verifyManifest,
+        cellSize = cellSize).isErr
+
+  test "Should not build from verifiable manifest with slots root":
+    let
+      slotBuilder = SlotsBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+      verifyManifest = (await slotBuilder.buildManifest()).tryGet()
+      offset = verifyManifest.verifyRoot.data.buffer.len div 2
+
+    rng.shuffle(
+      Rng.instance,
+      verifyManifest.verifyRoot.data.buffer)
+
+    check SlotsBuilder.new(
+        localStore,
+        verifyManifest,
+        cellSize = cellSize).isErr
+
+  test "Should build from verifiable manifest":
+    let
+      slotBuilder = SlotsBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+      verifyManifest = (await slotBuilder.buildManifest()).tryGet()
+
+      verificationBuilder = SlotsBuilder.new(
+        localStore,
+        verifyManifest,
+        cellSize = cellSize).tryGet()
+
+    check:
+      slotBuilder.slotRoots == verificationBuilder.slotRoots
+      slotBuilder.verifyRoot == verificationBuilder.verifyRoot
diff --git a/tests/codex/testchunking.nim b/tests/codex/testchunking.nim
index 860e52b6..99eec1c1 100644
--- a/tests/codex/testchunking.nim
+++ b/tests/codex/testchunking.nim
@@ -61,7 +61,7 @@ asyncchecksuite "Chunking":
 
   test "should chunk file":
     let
-      (path, _, _) = instantiationInfo(-2, fullPaths = true) # get this file's name
+      path = currentSourcePath()
       file = open(path)
       fileChunker = FileChunker.new(file = file, chunkSize = 256'nb, pad = false)
 
diff --git a/tests/codex/testerasure.nim b/tests/codex/testerasure.nim
index b108c6f7..0c7e08a5 100644
--- a/tests/codex/testerasure.nim
+++ b/tests/codex/testerasure.nim
@@ -39,8 +39,8 @@ suite "Erasure encode/decode":
     let
       encoded = (await erasure.encode(
         manifest,
-        buffers,
-        parity)).tryGet()
+        buffers.Natural,
+        parity.Natural)).tryGet()
 
     check:
       encoded.blocksCount mod (buffers + parity) == 0
diff --git a/tests/codex/testmanifest.nim b/tests/codex/testmanifest.nim
index 72878885..35feefb8 100644
--- a/tests/codex/testmanifest.nim
+++ b/tests/codex/testmanifest.nim
@@ -6,6 +6,10 @@ import pkg/asynctest
 import pkg/codex/chunker
 import pkg/codex/blocktype as bt
 import pkg/codex/manifest
+import pkg/poseidon2
+
+import pkg/codex/slots
+import pkg/codex/merkletree
 
 import ./helpers
 import ./examples
@@ -17,17 +21,30 @@ checksuite "Manifest":
       blockSize = 1.MiBs,
       datasetSize = 100.MiBs
     )
+
     protectedManifest = Manifest.new(
       manifest = manifest,
       treeCid = Cid.example,
       datasetSize = 200.MiBs,
-      eck = 10,
-      ecM = 10
+      eck = 2,
+      ecM = 2
     )
+
+    leaves = [
+      0.toF.Poseidon2Hash,
+      1.toF.Poseidon2Hash,
+      2.toF.Poseidon2Hash,
+      3.toF.Poseidon2Hash]
+
+    slotLeavesCids = leaves.toSlotCids().tryGet
+
+    tree = Poseidon2Tree.init(leaves).tryGet
+    slotsRootsCid = tree.root.tryGet.toSlotsRootsCid().tryGet
+
     verifiableManifest = Manifest.new(
       manifest = protectedManifest,
-      verificationRoot = Cid.example,
-      slotRoots = @[Cid.example, Cid.example]
+      verifyRoot = slotsRootsCid,
+      slotRoots = slotLeavesCids
     ).tryGet()
 
   proc encodeDecode(manifest: Manifest): Manifest =
diff --git a/tests/codex/testnode.nim b/tests/codex/testnode.nim
index 63b598c2..1ac99864 100644
--- a/tests/codex/testnode.nim
+++ b/tests/codex/testnode.nim
@@ -2,6 +2,8 @@ import std/os
 import std/options
 import std/math
 import std/times
+import std/sequtils
+import std/importutils
 
 import pkg/asynctest
 import pkg/chronos
@@ -11,6 +13,8 @@ import pkg/datastore
 import pkg/questionable
 import pkg/questionable/results
 import pkg/stint
+import pkg/poseidon2
+import pkg/poseidon2/io
 
 import pkg/nitro
 import pkg/codexdht/discv5/protocol as discv5
@@ -21,23 +25,61 @@ import pkg/codex/contracts
 import pkg/codex/systemclock
 import pkg/codex/blockexchange
 import pkg/codex/chunker
-import pkg/codex/node
+import pkg/codex/slots
 import pkg/codex/manifest
 import pkg/codex/discovery
+import pkg/codex/erasure
+import pkg/codex/merkletree
 import pkg/codex/blocktype as bt
 
+import pkg/codex/node {.all.}
+
 import ../examples
 import ./helpers
 import ./helpers/mockmarket
 import ./helpers/mockclock
 
+privateAccess(CodexNodeRef) # enable access to private fields
+
 proc toTimesDuration(d: chronos.Duration): times.Duration =
-  initDuration(seconds=d.seconds)
+  initDuration(seconds = d.seconds)
+
+proc drain(
+  stream: LPStream | Result[lpstream.LPStream, ref CatchableError]):
+  Future[seq[byte]] {.async.} =
 
-asyncchecksuite "Test Node":
   let
-    (path, _, _) = instantiationInfo(-2, fullPaths = true) # get this file's name
+    stream =
+      when typeof(stream) is Result[lpstream.LPStream, ref CatchableError]:
+        stream.tryGet()
+      else:
+        stream
 
+  defer:
+    await stream.close()
+
+  var data: seq[byte]
+  while not stream.atEof:
+    var
+      buf = newSeq[byte](DefaultBlockSize.int)
+      res = await stream.readOnce(addr buf[0], DefaultBlockSize.int)
+    check res <= DefaultBlockSize.int
+    buf.setLen(res)
+    data &= buf
+
+  data
+
+proc pipeChunker(stream: BufferStream, chunker: Chunker) {.async.} =
+  try:
+    while (
+      let chunk = await chunker.getBytes();
+      chunk.len > 0):
+      await stream.pushData(chunk)
+  finally:
+    await stream.pushEof()
+    await stream.close()
+
+template setupAndTearDown() {.dirty.} =
   var
     file: File
     chunker: Chunker
@@ -55,33 +97,13 @@ asyncchecksuite "Test Node":
     peerStore: PeerCtxStore
     pendingBlocks: PendingBlocksManager
     discovery: DiscoveryEngine
+    erasure: Erasure
 
-  proc fetch(T: type Manifest, chunker: Chunker): Future[Manifest] {.async.} =
-    # Collect blocks from Chunker into Manifest
-    await storeDataGetManifest(localStore, chunker)
-
-  proc retrieve(cid: Cid): Future[seq[byte]] {.async.} =
-    # Retrieve an entire file contents by file Cid
-    let
-      oddChunkSize = math.trunc(DefaultBlockSize.float/1.359).int  # Let's check that node.retrieve can correctly rechunk data
-      stream = (await node.retrieve(cid)).tryGet()
-    var
-      data: seq[byte]
-
-    defer: await stream.close()
-
-    while not stream.atEof:
-      var
-        buf = newSeq[byte](oddChunkSize)
-        res = await stream.readOnce(addr buf[0], oddChunkSize)
-      check res <= oddChunkSize
-      buf.setLen(res)
-      data &= buf
-
-    return data
+  let
+    path = currentSourcePath().parentDir
 
   setup:
-    file = open(path.splitFile().dir /../ "fixtures" / "test.jpg")
+    file = open(path /../ "fixtures" / "test.jpg")
     chunker = FileChunker.new(file = file, chunkSize = DefaultBlockSize)
     switch = newStandardSwitch()
     wallet = WalletRef.new(EthPrivateKey.random())
@@ -90,7 +112,7 @@ asyncchecksuite "Test Node":
     clock = SystemClock.new()
     localStoreMetaDs = SQLiteDatastore.new(Memory).tryGet()
     localStoreRepoDs = SQLiteDatastore.new(Memory).tryGet()
-    localStore = RepoStore.new(localStoreRepoDs, localStoreMetaDs, clock=clock)
+    localStore = RepoStore.new(localStoreRepoDs, localStoreMetaDs, clock = clock)
     await localStore.start()
 
     blockDiscovery = Discovery.new(
@@ -102,7 +124,8 @@ asyncchecksuite "Test Node":
     discovery = DiscoveryEngine.new(localStore, peerStore, network, blockDiscovery, pendingBlocks)
     engine = BlockExcEngine.new(localStore, wallet, network, discovery, peerStore, pendingBlocks)
     store = NetworkStore.new(engine, localStore)
-    node = CodexNodeRef.new(switch, store, engine, nil, blockDiscovery) # TODO: pass `Erasure`
+    erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
+    node = CodexNodeRef.new(switch, store, engine, erasure, blockDiscovery)
 
     await node.start()
 
@@ -110,9 +133,12 @@ asyncchecksuite "Test Node":
     close(file)
     await node.stop()
 
+asyncchecksuite "Test Node - Basic":
+  setupAndTearDown()
+
   test "Fetch Manifest":
     let
-      manifest = await Manifest.fetch(chunker)
+      manifest = await storeDataGetManifest(localStore, chunker)
 
       manifestBlock = bt.Block.new(
         manifest.encode().tryGet(),
@@ -127,7 +153,7 @@ asyncchecksuite "Test Node":
       fetched == manifest
 
   test "Block Batching":
-    let manifest = await Manifest.fetch(chunker)
+    let manifest = await storeDataGetManifest(localStore, chunker)
 
     for batchSize in 1..12:
       (await node.fetchBatched(
@@ -142,8 +168,9 @@ asyncchecksuite "Test Node":
     let
       stream = BufferStream.new()
       storeFut = node.store(stream)
-      oddChunkSize = math.trunc(DefaultBlockSize.float/3.14).NBytes  # Let's check that node.store can correctly rechunk these odd chunks
+      oddChunkSize = math.trunc(DefaultBlockSize.float / 3.14).NBytes  # Let's check that node.store can correctly rechunk these odd chunks
       oddChunker = FileChunker.new(file = file, chunkSize = oddChunkSize, pad = false)  # TODO: doesn't work with pad=tue
+
     var
       original: seq[byte]
 
@@ -159,14 +186,9 @@ asyncchecksuite "Test Node":
 
     let
       manifestCid = (await storeFut).tryGet()
-    check:
-      (await localStore.hasBlock(manifestCid)).tryGet()
-
-    let
       manifestBlock = (await localStore.getBlock(manifestCid)).tryGet()
       localManifest = Manifest.decode(manifestBlock).tryGet()
-
-    let data = await retrieve(manifestCid)
+      data = await (await node.retrieve(manifestCid)).drain()
 
     check:
       data.len == localManifest.datasetSize.int
@@ -186,80 +208,72 @@ asyncchecksuite "Test Node":
     await stream.readExactly(addr data[0], data.len)
     check string.fromBytes(data) == testString
 
+  test "Setup purchase request":
+    let
+      manifest = await storeDataGetManifest(localStore, chunker)
+      manifestBlock = bt.Block.new(
+        manifest.encode().tryGet(),
+        codec = ManifestCodec).tryGet()
 
-asyncchecksuite "Test Node - host contracts":
-  let
-    (path, _, _) = instantiationInfo(-2, fullPaths = true) # get this file's name
+      protected = (await erasure.encode(manifest, 3, 2)).tryGet()
+      builder = SlotsBuilder.new(localStore, protected).tryGet()
+      verifiable = (await builder.buildManifest()).tryGet()
+      verifiableBlock = bt.Block.new(
+        verifiable.encode().tryGet(),
+        codec = ManifestCodec).tryGet()
+
+    (await localStore.putBlock(manifestBlock)).tryGet()
+
+    let
+      request = (await node.setupRequest(
+        cid = manifestBlock.cid,
+        nodes = 5,
+        tolerance = 2,
+        duration = 100.u256,
+        reward = 2.u256,
+        proofProbability = 3.u256,
+        expiry = 200.u256,
+        collateral = 200.u256)).tryGet
+
+    check:
+      (await verifiableBlock.cid in localStore) == true
+      request.content.cid == $verifiableBlock.cid
+      request.content.merkleRoot == builder.verifyRoot.get.toBytes
+
+asyncchecksuite "Test Node - Host contracts":
+  setupAndTearDown()
 
   var
-    file: File
-    chunker: Chunker
-    switch: Switch
-    wallet: WalletRef
-    network: BlockExcNetwork
-    clock: MockClock
-    localStore: RepoStore
-    localStoreRepoDs: DataStore
-    localStoreMetaDs: DataStore
-    engine: BlockExcEngine
-    store: NetworkStore
     sales: Sales
-    node: CodexNodeRef
-    blockDiscovery: Discovery
-    peerStore: PeerCtxStore
-    pendingBlocks: PendingBlocksManager
-    discovery: DiscoveryEngine
+    purchasing: Purchasing
     manifest: Manifest
-    manifestCid: string
-
-  proc fetch(T: type Manifest, chunker: Chunker): Future[Manifest] {.async.} =
-    # Collect blocks from Chunker into Manifest
-    await storeDataGetManifest(localStore, chunker)
+    manifestCidStr: string
+    manifestCid: Cid
+    market: MockMarket
 
   setup:
-    file = open(path.splitFile().dir /../ "fixtures" / "test.jpg")
-    chunker = FileChunker.new(file = file, chunkSize = DefaultBlockSize)
-    switch = newStandardSwitch()
-    wallet = WalletRef.new(EthPrivateKey.random())
-    network = BlockExcNetwork.new(switch)
-
-    clock = MockClock.new()
-    localStoreMetaDs = SQLiteDatastore.new(Memory).tryGet()
-    localStoreRepoDs = SQLiteDatastore.new(Memory).tryGet()
-    localStore = RepoStore.new(localStoreRepoDs, localStoreMetaDs, clock=clock)
-    await localStore.start()
-
-    blockDiscovery = Discovery.new(
-      switch.peerInfo.privateKey,
-      announceAddrs = @[MultiAddress.init("/ip4/127.0.0.1/tcp/0")
-        .expect("Should return multiaddress")])
-    peerStore = PeerCtxStore.new()
-    pendingBlocks = PendingBlocksManager.new()
-    discovery = DiscoveryEngine.new(localStore, peerStore, network, blockDiscovery, pendingBlocks)
-    engine = BlockExcEngine.new(localStore, wallet, network, discovery, peerStore, pendingBlocks)
-    store = NetworkStore.new(engine, localStore)
-    node = CodexNodeRef.new(switch, store, engine, nil, blockDiscovery) # TODO: pass `Erasure`
-
     # Setup Host Contracts and dependencies
-    let market = MockMarket.new()
+    market = MockMarket.new()
     sales = Sales.new(market, clock, localStore)
-    let hostContracts = some HostInteractions.new(clock, sales)
-    node.contracts = (ClientInteractions.none, hostContracts, ValidatorInteractions.none)
+
+    node.contracts = (
+      none ClientInteractions,
+      some HostInteractions.new(clock, sales),
+      none ValidatorInteractions)
 
     await node.start()
 
     # Populate manifest in local store
     manifest = await storeDataGetManifest(localStore, chunker)
-    let manifestBlock = bt.Block.new(
+    let
+      manifestBlock = bt.Block.new(
         manifest.encode().tryGet(),
-        codec = ManifestCodec
-      ).tryGet()
-    manifestCid = $(manifestBlock.cid)
-    (await localStore.putBlock(manifestBlock)).tryGet()
+        codec = ManifestCodec).tryGet()
 
-  teardown:
-    close(file)
-    await node.stop()
+    manifestCid = manifestBlock.cid
+    manifestCidStr = $(manifestCid)
+
+    (await localStore.putBlock(manifestBlock)).tryGet()
 
   test "onExpiryUpdate callback is set":
     check sales.onExpiryUpdate.isSome
@@ -270,12 +284,13 @@ asyncchecksuite "Test Node - host contracts":
       expectedExpiry: SecondsSince1970 = clock.now + DefaultBlockTtl.seconds + 11123
       expiryUpdateCallback = !sales.onExpiryUpdate
 
-    (await expiryUpdateCallback(manifestCid, expectedExpiry)).tryGet()
+    (await expiryUpdateCallback(manifestCidStr, expectedExpiry)).tryGet()
 
     for index in 0..<manifest.blocksCount:
-      let blk = (await localStore.getBlock(manifest.treeCid, index)).tryGet
-      let expiryKey = (createBlockExpirationMetadataKey(blk.cid)).tryGet
-      let expiry = await localStoreMetaDs.get(expiryKey)
+      let
+        blk = (await localStore.getBlock(manifest.treeCid, index)).tryGet
+        expiryKey = (createBlockExpirationMetadataKey(blk.cid)).tryGet
+        expiry = await localStoreMetaDs.get(expiryKey)
 
       check (expiry.tryGet).toSecondsSince1970 == expectedExpiry
 
@@ -285,7 +300,7 @@ asyncchecksuite "Test Node - host contracts":
   test "onStore callback":
     let onStore = !sales.onStore
     var request = StorageRequest.example
-    request.content.cid = manifestCid
+    request.content.cid = manifestCidStr
     request.expiry = (getTime() + DefaultBlockTtl.toTimesDuration + 1.hours).toUnix.u256
     var fetchedBytes: uint = 0
 
@@ -298,8 +313,9 @@ asyncchecksuite "Test Node - host contracts":
     check fetchedBytes == 2293760
 
     for index in 0..<manifest.blocksCount:
-      let blk = (await localStore.getBlock(manifest.treeCid, index)).tryGet
-      let expiryKey = (createBlockExpirationMetadataKey(blk.cid)).tryGet
-      let expiry = await localStoreMetaDs.get(expiryKey)
+      let
+        blk = (await localStore.getBlock(manifest.treeCid, index)).tryGet
+        expiryKey = (createBlockExpirationMetadataKey(blk.cid)).tryGet
+        expiry = await localStoreMetaDs.get(expiryKey)
 
       check (expiry.tryGet).toSecondsSince1970 == request.expiry.toSecondsSince1970
diff --git a/tests/integration/testIntegration.nim b/tests/integration/testIntegration.nim
index ca674dd9..7863cba3 100644
--- a/tests/integration/testIntegration.nim
+++ b/tests/integration/testIntegration.nim
@@ -15,7 +15,6 @@ import ../codex/helpers
 import ../examples
 import ./twonodes
 
-
 # For debugging you can enable logging output with debugX = true
 # You can also pass a string in same format like for the `--log-level` parameter
 # to enable custom logging levels for specific topics like: debug2 = "INFO; TRACE: marketplace"
@@ -140,7 +139,7 @@ twonodessuite "Integration tests", debug1 = false, debug2 = false:
     check request.ask.proofProbability == 3.u256
     check request.expiry == expiry
     check request.ask.collateral == 200.u256
-    check request.ask.slots == 3'u64
+    check request.ask.slots == 2'u64
     check request.ask.maxSlotLoss == 1'u64
 
   # TODO: We currently do not support encoding single chunks
@@ -181,7 +180,6 @@ twonodessuite "Integration tests", debug1 = false, debug2 = false:
     check request.ask.slots == 1'u64
     check request.ask.maxSlotLoss == 0'u64
 
-
   test "nodes negotiate contracts on the marketplace":
     let size = 0xFFFFF.u256
     # client 2 makes storage available
@@ -227,6 +225,21 @@ twonodessuite "Integration tests", debug1 = false, debug2 = false:
 
     check eventually (await token.balanceOf(account2)) - startBalance == duration*reward
 
+  test "request storage fails if nodes and tolerance aren't correct":
+    let cid = client1.upload("some file contents").get
+    let expiry = (await ethProvider.currentTime()) + 30
+    let responseBefore = client1.requestStorageRaw(cid,
+      duration=100.u256,
+      reward=2.u256,
+      proofProbability=3.u256,
+      expiry=expiry,
+      collateral=200.u256,
+      nodes=1,
+      tolerance=1)
+
+    check responseBefore.status == "400 Bad Request"
+    check responseBefore.body == "Tolerance cannot be greater or equal than nodes (nodes - tolerance)"
+
   test "node requires expiry and its value to be in future":
     let currentTime = await ethProvider.currentTime()
     let cid = client1.upload("some file contents").get
diff --git a/vendor/nim-poseidon2 b/vendor/nim-poseidon2
index 3b403b07..eef2603c 160000
--- a/vendor/nim-poseidon2
+++ b/vendor/nim-poseidon2
@@ -1 +1 @@
-Subproject commit 3b403b0752790438bed6342b431412cc05474acb
+Subproject commit eef2603c11eeb5069eaed6c0296f3a1c5d23aad1