diff --git a/codex/slotbuilder/slotbuilder.nim b/codex/slotbuilder/slotbuilder.nim
deleted file mode 100644
index 426c6a2b..00000000
--- a/codex/slotbuilder/slotbuilder.nim
+++ /dev/null
@@ -1,109 +0,0 @@
-import std/math
-import std/sequtils
-import pkg/libp2p
-import pkg/chronos
-import pkg/chronicles
-import pkg/questionable/results
-import ../merkletree
-import ../stores
-import ../manifest
-import ../utils
-import ../utils/digest
-
-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
-
-type
-  SlotBuilder* = object of RootObj
-    blockStore: BlockStore
-    manifest: Manifest
-    slotBlocks: int
-
-proc new*(
-    T: type SlotBuilder,
-    blockStore: BlockStore,
-    manifest: Manifest
-): ?!SlotBuilder =
-
-  if not manifest.protected:
-    return failure("Can only create SlotBuilder using protected manifests.")
-
-  if (manifest.blocksCount mod manifest.ecK) != 0:
-    return failure("Number of blocks must be divisable by number of slots.")
-
-  if (manifest.blockSize.int mod CellSize) != 0:
-    return failure("Block size must be divisable by cell size.")
-
-  let slotBlocks = manifest.blocksCount div manifest.numberOfSlots
-  success SlotBuilder(
-    blockStore: blockStore,
-    manifest: manifest,
-    slotBlocks: slotBlocks)
-
-proc cellsPerBlock(self: SlotBuilder): int =
-  self.manifest.blockSize.int div CellSize
-
-proc selectSlotBlocks*(
-  self: SlotBuilder,
-  slotIndex: int): Future[?!seq[Poseidon2Hash]] {.async.} =
-
-  let
-    treeCid = self.manifest.treeCid
-    blockCount = self.manifest.blocksCount
-    numberOfSlots = self.manifest.numberOfSlots
-    strategy = SteppedIndexingStrategy.new(0, blockCount - 1, numberOfSlots)
-
-  logScope:
-    treeCid = treeCid
-    blockCount = blockCount
-    numberOfSlots = numberOfSlots
-    index = blockIndex
-
-  var blocks = newSeq[Poseidon2Hash]()
-  for blockIndex in strategy.getIndicies(slotIndex):
-    without blk =? await self.blockStore.getBlock(treeCid, blockIndex), err:
-      error "Failed to get block CID for tree at index"
-
-      return failure(err)
-
-    without digestTree =? Poseidon2Tree.digest(blk.data, CellSize) and
-        blockDigest =? digestTree.root, err:
-      error "Failed to create digest for block"
-
-      return failure(err)
-
-    blocks.add(blockDigest)
-    # TODO: Remove this sleep. It's here to prevent us from locking up the thread.
-    await sleepAsync(10.millis)
-
-  success blocks
-
-proc numPaddingCells*(self: SlotBuilder, slotBlocks: int): int =
-  let
-    numberOfCells = slotBlocks * self.cellsPerBlock
-    nextPowerOfTwo = nextPowerOfTwo(numberOfCells)
-
-  return nextPowerOfTwo - numberOfCells
-
-proc buildSlotTree*(self: SlotBuilder, slotBlocks: seq[Cid], paddingCells: int): ?!Poseidon2Tree =
-  without emptyCid =? emptyCid(self.manifest.version, self.manifest.hcodec, self.manifest.codec), err:
-    error "Unable to initialize empty cid"
-    return failure(err)
-
-  let paddingBlocks = divUp(paddingCells, self.cellsPerBlock)
-  let padding = newSeqWith(paddingBlocks, emptyCid)
-
-  Poseidon2Tree.init(slotBlocks & padding)
-
-proc createSlots*(self: SlotBuilder, slotIndex: int): Future[?!Manifest] {.async.} =
-  without slotBlocks =? await self.selectSlotBlocks(slotIndex), err:
-    error "Failed to select slot blocks"
-    return failure(err)
-
-  let paddingCells = self.numPaddingCells(slotBlocks.len)
-
-  trace "Creating slot tree", slotIndex, nSlotBlocks = slotBlocks.len, paddingCells
-  return self.buildSlotTree(slotBlocks, paddingCells)
diff --git a/codex/slots/slotbuilder.nim b/codex/slots/slotbuilder.nim
new file mode 100644
index 00000000..343a6893
--- /dev/null
+++ b/codex/slots/slotbuilder.nim
@@ -0,0 +1,267 @@
+## 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.
+
+{.push raises: [].}
+
+import std/math
+import std/sequtils
+import std/sugar
+
+import pkg/libp2p
+import pkg/chronos
+import pkg/chronicles
+import pkg/questionable/results
+import pkg/poseidon2
+import pkg/poseidon2/io
+
+import ../indexingstrategy
+import ../merkletree
+import ../stores
+import ../manifest
+import ../utils
+import ../utils/digest
+
+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
+
+type
+  SlotBuilder* = object of RootObj
+    store: BlockStore
+    manifest: Manifest
+    strategy: IndexingStrategy
+    cellSize: int
+    blockPadBytes: seq[byte]
+    slotsPadLeafs: seq[Poseidon2Hash]
+    rootsPadLeafs: seq[Poseidon2Hash]
+
+func numBlockPadBytes*(self: SlotBuilder): Natural =
+  ## Number of padding bytes required for a pow2
+  ## merkle tree for each block.
+  ##
+
+  self.blockPadBytes.len
+
+func numSlotsPadLeafs*(self: SlotBuilder): Natural =
+  ## Number of padding field elements required for a pow2
+  ## merkle tree for each slot.
+  ##
+
+  self.slotsPadLeafs.len
+
+func numRootsPadLeafs*(self: SlotBuilder): Natural =
+  ## Number of padding field elements required for a pow2
+  ## merkle tree for the slot roots.
+  ##
+
+  self.rootsPadLeafs.len
+
+func numSlotBlocks*(self: SlotBuilder): Natural =
+  ## Number of blocks per slot.
+  ##
+
+  self.manifest.blocksCount div self.manifest.numSlots
+
+func numBlockRoots*(self: SlotBuilder): Natural =
+  ## Number of cells per block.
+  ##
+
+  self.manifest.blockSize.int div self.cellSize
+
+func toCellCid(cell: Poseidon2Hash): ?!Cid =
+  let
+    cellMhash = ? MultiHash.init(Pos2Bn128MrklCodec, cell.toBytes).mapFailure
+    cellCid = ? Cid.init(CIDv1, CodexSlotCell, cellMhash).mapFailure
+
+  success cellCid
+
+func toSlotCid(root: Poseidon2Hash): ?!Cid =
+  let
+    mhash = ? MultiHash.init($multiCodec("identity"), root.toBytes).mapFailure
+    treeCid = ? Cid.init(CIDv1, SlotRootCodec, mhash).mapFailure
+
+  success treeCid
+
+func toProvingCid(root: Poseidon2Hash): ?!Cid =
+  let
+    mhash = ? MultiHash.init($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 =
+
+  let
+    encodableProof = CodexProof(
+      mcodec: multiCodec("identity"), # copy bytes as is
+      index: proof.index,
+      nleaves: proof.nleaves,
+      path: proof.path.mapIt( @(it.toBytes) ))
+
+  success encodableProof
+
+func toVerifiableProof*(
+  proof: CodexProof): ?!Poseidon2Proof =
+
+  let
+    verifiableProof = Poseidon2Proof(
+      index: proof.index,
+      nleaves: proof.nleaves,
+      path: proof.path.mapIt(
+        ? Poseidon2Hash.fromBytes(it.toArray32).toResult
+      ))
+
+  success verifiableProof
+
+proc getCellHashes*(
+  self: SlotBuilder,
+  slotIndex: int): Future[?!seq[Poseidon2Hash]] {.async.} =
+
+  let
+    treeCid = self.manifest.treeCid
+    blockCount = self.manifest.blocksCount
+    numberOfSlots = self.manifest.numSlots
+
+  logScope:
+    treeCid = treeCid
+    blockCount = blockCount
+    numberOfSlots = numberOfSlots
+    index = blockIndex
+    slotIndex = slotIndex
+
+  let
+    hashes: seq[Poseidon2Hash] = collect(newSeq):
+      for blockIndex in self.strategy.getIndicies(slotIndex):
+        trace "Getting block CID for tree at index"
+
+        without blk =? (await self.store.getBlock(treeCid, blockIndex)), err:
+          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)
+
+        # TODO: Remove this sleep. It's here to prevent us from locking up the thread.
+        # await sleepAsync(10.millis)
+
+        digest
+
+  success hashes
+
+proc buildSlotTree*(
+  self: SlotBuilder,
+  slotIndex: int): Future[?!Poseidon2Tree] {.async.} =
+  without cellHashes =? (await self.getCellHashes(slotIndex)), err:
+    error "Failed to select slot blocks", err = err.msg
+    return failure(err)
+
+  Poseidon2Tree.init(cellHashes & self.slotsPadLeafs)
+
+proc buildSlot*(
+  self: SlotBuilder,
+  slotIndex: int): Future[?!Poseidon2Hash] {.async.} =
+  ## Build a slot tree and store it in the block store.
+  ##
+
+  without tree =? (await self.buildSlotTree(slotIndex)) and
+    treeCid =? tree.root.?toSlotCid, err:
+    error "Failed to build slot tree", err = err.msg
+    return failure(err)
+
+  trace "Storing slot tree", treeCid, slotIndex, leaves = tree.leavesCount
+  for i, leaf in tree.leaves:
+    without cellCid =? leaf.toCellCid, err:
+      error "Failed to get CID for slot cell", err = err.msg
+      return failure(err)
+
+    without proof =? tree.getProof(i) and
+      encodableProof =? proof.toEncodableProof, err:
+      error "Failed to get proof for slot tree", err = err.msg
+      return failure(err)
+
+    if err =? (await self.store.putCidAndProof(
+      treeCid, i, cellCid, encodableProof)).errorOption:
+      error "Failed to store slot tree", err = err.msg
+      return failure(err)
+
+  tree.root()
+
+proc buildSlots(self: SlotBuilder): Future[?!Manifest] {.async.} =
+  let
+    slotRoots: seq[Poseidon2Hash] = collect(newSeq):
+      for i in 0..<self.manifest.numSlots:
+        without root =? (await self.buildSlot(i)), err:
+          error "Failed to build slot", err = err.msg, index = i
+          return failure(err)
+        root
+
+  without provingRootCid =? Poseidon2Tree.init(slotRoots & self.rootsPadLeafs).?root.?toProvingCid, err:
+    error "Failed to build proving tree", err = err.msg
+    return failure(err)
+
+  without rootCids =? slotRoots.mapToSlotCids(), err:
+    error "Failed to map slot roots to CIDs", err = err.msg
+    return failure(err)
+
+  Manifest.new(self.manifest, provingRootCid, rootCids)
+
+func nextPowerOfTwoPad*(a: int): int =
+  ## Returns the next power of two of `a` and `b` and the difference between
+  ## the original value and the next power of two.
+  ##
+
+  nextPowerOfTwo(a) - a
+
+proc new*(
+  T: type SlotBuilder,
+  store: BlockStore,
+  manifest: Manifest,
+  strategy: IndexingStrategy = nil,
+  cellSize = CellSize): ?!SlotBuilder =
+
+  if not manifest.protected:
+    return failure("Can only create SlotBuilder using protected manifests.")
+
+  if (manifest.blocksCount mod manifest.numSlots) != 0:
+    return failure("Number of blocks must be divisable by number of slots.")
+
+  if (manifest.blockSize.int mod cellSize) != 0:
+    return failure("Block size must be divisable by cell size.")
+
+  let
+    strategy = if strategy == nil:
+      SteppedIndexingStrategy.new(
+        0, manifest.blocksCount - 1, manifest.numSlots)
+      else:
+        strategy
+
+    # all trees have to be padded to power of two
+    numBlockCells = manifest.blockSize.int div cellSize                       # number of cells per block
+    blockPadBytes
+      = newSeq[byte](numBlockCells.nextPowerOfTwoPad * cellSize)  # power of two padding for blocks
+    slotsPadLeafs
+      = newSeqWith((manifest.blocksCount div manifest.numSlots).nextPowerOfTwoPad, Poseidon2Zero)                                                  # power of two padding for block roots
+    rootsPadLeafs
+      = newSeqWith(manifest.numSlots.nextPowerOfTwoPad, Poseidon2Zero)
+
+  success SlotBuilder(
+    store: store,
+    manifest: manifest,
+    strategy: strategy,
+    cellSize: cellSize,
+    blockPadBytes: blockPadBytes,
+    slotsPadLeafs: slotsPadLeafs,
+    rootsPadLeafs: rootsPadLeafs)
diff --git a/tests/codex/slotbuilder/testslotbuilder.nim b/tests/codex/slotbuilder/testslotbuilder.nim
index d9ab78c0..b4763de0 100644
--- a/tests/codex/slotbuilder/testslotbuilder.nim
+++ b/tests/codex/slotbuilder/testslotbuilder.nim
@@ -1,5 +1,8 @@
 import std/sequtils
 import std/math
+import std/importutils
+import std/sugar
+
 import pkg/chronos
 import pkg/asynctest
 import pkg/questionable/results
@@ -9,29 +12,53 @@ import pkg/codex/stores
 import pkg/codex/chunker
 import pkg/codex/merkletree
 import pkg/codex/utils
+import pkg/codex/utils/digest
+import pkg/datastore
+import pkg/poseidon2
+import pkg/poseidon2/io
+import constantine/math/io/io_fields
 
 import ../helpers
 import ../examples
+import ../merkletree/helpers
 
-import pkg/codex/manifest/indexingstrategy
-import pkg/codex/slotbuilder/slotbuilder
+import pkg/codex/indexingstrategy {.all.}
+import pkg/codex/slots/slotbuilder {.all.}
 
-asyncchecksuite "Slot builder":
+suite "Slot builder":
   let
-    blockSize = 64 * 1024
-    numberOfCellsPerBlock = blockSize div CellSize
-    numberOfSlotBlocks = 6
-    numberOfSlots = 5
-    numberOfDatasetBlocks = numberOfSlotBlocks * numberOfSlots
-    datasetSize = numberOfDatasetBlocks * blockSize
-    chunker = RandomChunker.new(Rng.instance(), size = datasetSize, chunkSize = blockSize)
+    blockSize = 1024
+    cellSize = 64
+    ecK = 3
+    ecM = 2
+
+    numSlots = ecK + ecM
+    numDatasetBlocks = 100
+    numBlockCells = blockSize div cellSize
+
+    numTotalBlocks = calcEcBlocksCount(numDatasetBlocks, ecK, ecM)                # total number of blocks in the dataset after
+                                                                                  # EC (should will match number of slots)
+    originalDatasetSize = numDatasetBlocks * blockSize                            # size of the dataset before EC
+    totalDatasetSize = numTotalBlocks * blockSize                                 # size of the dataset after EC
+    numTotalSlotBlocks = nextPowerOfTwo(numTotalBlocks div numSlots)
+
+    blockPadBytes =
+      newSeq[byte](numBlockCells.nextPowerOfTwoPad * cellSize)                    # power of two padding for blocks
+
+    slotsPadLeafs =
+      newSeqWith((numTotalBlocks div numSlots).nextPowerOfTwoPad, Poseidon2Zero)  # power of two padding for block roots
+
+    rootsPadLeafs =
+      newSeqWith(numSlots.nextPowerOfTwoPad, Poseidon2Zero)
 
   var
     datasetBlocks: seq[bt.Block]
-    localStore = CacheStore.new()
+    localStore: BlockStore
+    manifest: Manifest
     protectedManifest: Manifest
     expectedEmptyCid: Cid
     slotBuilder: SlotBuilder
+    chunker: Chunker
 
   proc createBlocks(): Future[void] {.async.} =
     while true:
@@ -45,132 +72,225 @@ asyncchecksuite "Slot builder":
   proc createProtectedManifest(): Future[void] {.async.} =
     let
       cids = datasetBlocks.mapIt(it.cid)
-      tree = Poseidon2Tree.init(cids).tryGet()
-      treeCid = tree.rootCid().tryGet()
+      datasetTree = CodexTree.init(cids[0..<numDatasetBlocks]).tryGet()
+      datasetTreeCid = datasetTree.rootCid().tryGet()
+
+      protectedTree = CodexTree.init(cids).tryGet()
+      protectedTreeCid = protectedTree.rootCid().tryGet()
+
+    for index, cid in cids[0..<numDatasetBlocks]:
+      let proof = datasetTree.getProof(index).tryget()
+      (await localStore.putCidAndProof(datasetTreeCid, index, cid, proof)).tryGet
 
     for index, cid in cids:
-      let proof = tree.getProof(index).tryget()
-      discard await localStore.putBlockCidAndProof(treeCid, index, cid, proof)
+      let proof = protectedTree.getProof(index).tryget()
+      (await localStore.putCidAndProof(protectedTreeCid, index, cid, proof)).tryGet
+
+    manifest = Manifest.new(
+      treeCid = datasetTreeCid,
+      blockSize = blockSize.NBytes,
+      datasetSize = originalDatasetSize.NBytes)
 
     protectedManifest = Manifest.new(
-      manifest = Manifest.new(
-        treeCid = treeCid,
-        blockSize = blockSize.NBytes,
-        datasetSize = datasetSize.NBytes),
-      treeCid = treeCid,
-      datasetSize = datasetSize.NBytes,
-      ecK = numberOfSlots,
-      ecM = 0
-    )
+      manifest = manifest,
+      treeCid = protectedTreeCid,
+      datasetSize = totalDatasetSize.NBytes,
+      ecK = ecK,
+      ecM = ecM)
 
-    let manifestBlock = bt.Block.new(protectedManifest.encode().tryGet(), codec = DagPBCodec).tryGet()
-    discard await localStore.putBlock(manifestBlock)
-    expectedEmptyCid = emptyCid(protectedManifest.version, protectedManifest.hcodec, protectedManifest.codec).tryget()
+    let
+      manifestBlock = bt.Block.new(
+        manifest.encode().tryGet(),
+        codec = ManifestCodec).tryGet()
+
+      protectedManifestBlock = bt.Block.new(
+        protectedManifest.encode().tryGet(),
+        codec = ManifestCodec).tryGet()
+
+    (await localStore.putBlock(manifestBlock)).tryGet()
+    (await localStore.putBlock(protectedManifestBlock)).tryGet()
+
+    expectedEmptyCid = emptyCid(
+      protectedManifest.version,
+      protectedManifest.hcodec,
+      protectedManifest.codec).tryGet()
+
+  privateAccess(SlotBuilder) # enable access to private fields
 
   setup:
+    let
+      repoDs = SQLiteDatastore.new(Memory).tryGet()
+      metaDs = SQLiteDatastore.new(Memory).tryGet()
+    localStore = RepoStore.new(repoDs, metaDs)
+
+    chunker = RandomChunker.new(Rng.instance(), size = totalDatasetSize, chunkSize = blockSize)
     await createBlocks()
     await createProtectedManifest()
-    slotBuilder = SlotBuilder.new(localStore, protectedManifest).tryGet()
+
+  teardown:
+    await localStore.close()
+
+    # Need to reset all objects because otherwise they get
+    # captured by the test runner closures, not good!
+    reset(datasetBlocks)
+    reset(localStore)
+    reset(manifest)
+    reset(protectedManifest)
+    reset(expectedEmptyCid)
+    reset(slotBuilder)
+    reset(chunker)
 
   test "Can only create slotBuilder with protected manifest":
-    let unprotectedManifest = Manifest.new(
-      treeCid = Cid.example,
-      blockSize = blockSize.NBytes,
-      datasetSize = datasetSize.NBytes)
-
-    check:
-      SlotBuilder.new(localStore, unprotectedManifest).isErr
-
-  test "Number of blocks must be devisable by number of slots":
-    let mismatchManifest = Manifest.new(
-      manifest = Manifest.new(
+    let
+      unprotectedManifest = Manifest.new(
         treeCid = Cid.example,
         blockSize = blockSize.NBytes,
-        datasetSize = datasetSize.NBytes),
-      treeCid = Cid.example,
-      datasetSize = datasetSize.NBytes,
-      ecK = numberOfSlots - 1,
-      ecM = 0
-    )
+        datasetSize = originalDatasetSize.NBytes)
 
     check:
-      SlotBuilder.new(localStore, mismatchManifest).isErr
+      SlotBuilder.new(localStore, unprotectedManifest, cellSize = cellSize)
+        .error.msg == "Can only create SlotBuilder using protected manifests."
+
+  test "Number of blocks must be devisable by number of slots":
+    let
+      mismatchManifest = Manifest.new(
+        manifest = Manifest.new(
+          treeCid = Cid.example,
+          blockSize = blockSize.NBytes,
+          datasetSize = originalDatasetSize.NBytes),
+        treeCid = Cid.example,
+        datasetSize = totalDatasetSize.NBytes,
+        ecK = ecK - 1,
+        ecM = ecM)
+
+    check:
+      SlotBuilder.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":
-    let mismatchManifest = Manifest.new(
-      manifest = Manifest.new(
-        treeCid = Cid.example,
-        blockSize = (blockSize - 1).NBytes,
-        datasetSize = (datasetSize - numberOfDatasetBlocks).NBytes),
-      treeCid = Cid.example,
-      datasetSize = (datasetSize - numberOfDatasetBlocks).NBytes,
-      ecK = numberOfSlots,
-      ecM = 0
-    )
-
-    check:
-      SlotBuilder.new(localStore, mismatchManifest).isErr
-
-  for nSlotBlocks in [1, 12, 123, 1234, 12345]:
-    test "Can calculate the number of padding cells (" & $nSlotBlocks & ")":
-      let
-        nPadCells = slotBuilder.calculateNumberOfPaddingCells(nSlotBlocks)
-        totalSlotBytes = nSlotBlocks * blockSize
-        totalSlotCells = totalSlotBytes div CellSize
-        expectedPadCells = nextPowerOfTwo(totalSlotCells) - totalSlotCells
-      check:
-        expectedPadCells == nPadCells
-
-  for i in 0 ..< numberOfSlots:
-    test "Can select slot block CIDs (index: " & $i & ")":
-      let
-        steppedStrategy = SteppedIndexingStrategy.new(0, numberOfDatasetBlocks - 1, numberOfSlots)
-        expectedDatasetBlockIndicies = steppedStrategy.getIndicies(i)
-        expectedBlockCids = expectedDatasetBlockIndicies.mapIt(datasetBlocks[it].cid)
-
-        slotBlockCids = (await slotBuilder.selectSlotBlocks(i)).tryGet()
-
-      check:
-        expectedBlockCids == slotBlockCids
-
-    test "Can create slot tree (index: " & $i & ")":
-      let
-        expectedSlotBlockCids = (await slotBuilder.selectSlotBlocks(i)).tryGet()
-        expectedNumPadBlocks = divUp(slotBuilder.calculateNumberOfPaddingCells(expectedSlotBlockCids.len), numberOfCellsPerBlock)
-
-        slotTree = (await slotBuilder.createSlotTree(i)).tryGet()
-
-      check:
-        # Tree size
-        slotTree.leavesCount == expectedSlotBlockCids.len + expectedNumPadBlocks
-
-      for i in 0 ..< numberOfSlotBlocks:
-        check:
-          # Each slot block
-          slotTree.getLeafCid(i).tryget() == expectedSlotBlockCids[i]
-
-      for i in 0 ..< expectedNumPadBlocks:
-        check:
-          # Each pad block
-          slotTree.getLeafCid(numberOfSlotBlocks + i).tryget() == expectedEmptyCid
-
-  test "Can create slot tree":
     let
-      slotBlockCids = datasetBlocks[0 ..< numberOfSlotBlocks].mapIt(it.cid)
-      numPadCells = numberOfCellsPerBlock div 2 # We expect 1 pad block.
-
-      slotTree = slotBuilder.buildSlotTree(slotBlockCids, numPadCells).tryGet()
+      mismatchManifest = Manifest.new(
+        manifest = Manifest.new(
+          treeCid = Cid.example,
+          blockSize = (blockSize + 1).NBytes,
+          datasetSize = (originalDatasetSize - 1).NBytes),
+        treeCid = Cid.example,
+        datasetSize = (totalDatasetSize - 1).NBytes,
+        ecK = ecK,
+        ecM = ecM)
 
     check:
-      # Tree size
-      slotTree.leavesCount == slotBlockCids.len + 1
+      SlotBuilder.new(localStore, mismatchManifest, cellSize = cellSize)
+        .error.msg == "Block size must be divisable by cell size."
+
+  test "Should build correct slot builder":
+    slotBuilder = SlotBuilder.new(
+      localStore,
+      protectedManifest,
+      cellSize = cellSize).tryGet()
+
+    check:
+      slotBuilder.numBlockPadBytes == blockPadBytes.len
+      slotBuilder.numSlotsPadLeafs == slotsPadLeafs.len
+      slotBuilder.numRootsPadLeafs == rootsPadLeafs.len
+
+  test "Should build slot hashes for all slots":
+    let
+      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      slotBuilder = SlotBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+    for i in 0 ..< numSlots:
+      let
+        expectedBlock = steppedStrategy
+          .getIndicies(i)
+          .mapIt( datasetBlocks[it] )
+
+        expectedHashes: seq[Poseidon2Hash] = collect(newSeq):
+          for blk in expectedBlock:
+            SpongeMerkle.digest(blk.data & blockPadBytes, cellSize)
+
+        cellHashes = (await slotBuilder.getCellHashes(i)).tryGet()
 
-    for i in 0 ..< numberOfSlotBlocks:
       check:
-        # Each slot block
-        slotTree.getLeafCid(i).tryget() == slotBlockCids[i]
+        expectedHashes == cellHashes
+
+  test "Should build slot trees for all slots":
+    let
+      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      slotBuilder = SlotBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+    for i in 0 ..< numSlots:
+      let
+        expectedBlock = steppedStrategy
+          .getIndicies(i)
+          .mapIt( datasetBlocks[it] )
+
+        expectedHashes: seq[Poseidon2Hash] = collect(newSeq):
+          for blk in expectedBlock:
+            SpongeMerkle.digest(blk.data & blockPadBytes, cellSize)
+        expectedRoot = Merkle.digest(expectedHashes & slotsPadLeafs)
+
+        slotTree = (await slotBuilder.buildSlotTree(i)).tryGet()
+
+      check:
+        expectedRoot == slotTree.root().tryGet()
+
+  test "Should persist trees for all slots":
+    let
+      slotBuilder = SlotBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+    for i in 0 ..< numSlots:
+      let
+        slotTree = (await slotBuilder.buildSlotTree(i)).tryGet()
+        slotRoot = (await slotBuilder.buildSlot(i)).tryGet()
+        slotCid = slotRoot.toSlotCid().tryGet()
+
+      for cellIndex in 0..<numTotalSlotBlocks:
+        let
+          (cellCid, proof) = (await localStore.getCidAndProof(slotCid, cellIndex)).tryGet()
+          verifiableProof = proof.toVerifiableProof().tryGet()
+          posProof = slotTree.getProof(cellIndex).tryGet
+
+        check:
+          verifiableProof.index == posProof.index
+          verifiableProof.nleaves == posProof.nleaves
+          verifiableProof.path == posProof.path
+
+  test "Should build correct verification root":
+    let
+      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      slotBuilder = SlotBuilder.new(
+        localStore,
+        protectedManifest,
+        cellSize = cellSize).tryGet()
+
+      slotsHashes = collect(newSeq):
+        for i in 0 ..< numSlots:
+          let
+            expectedBlocks = steppedStrategy
+              .getIndicies(i)
+              .mapIt( datasetBlocks[it] )
+
+            slotHashes: seq[Poseidon2Hash] = collect(newSeq):
+              for blk in expectedBlocks:
+                SpongeMerkle.digest(blk.data & blockPadBytes, cellSize)
+
+          Merkle.digest(slotHashes & slotsPadLeafs)
+
+      expectedRoot = Merkle.digest(slotsHashes & rootsPadLeafs)
+      manifest = (await slotBuilder.buildSlots()).tryGet()
+      mhash = manifest.verificationRoot.mhash.tryGet()
+      mhashBytes = mhash.digestBytes
+      rootHash = Poseidon2Hash.fromBytes(mhashBytes.toArray32).toResult.tryGet()
 
     check:
-      # 1 pad block
-      slotTree.getLeafCid(numberOfSlotBlocks).tryget() == expectedEmptyCid
-
+      expectedRoot == rootHash