Implement FetchBlock SyncService method via node kernel access

Adds in-process block fetching from ChainDB, bypassing N2C IPC.
Response includes raw CBOR bytes and cardano block header (slot, hash, height).

Author: carbolymer

.changes/20260602_cardano_api_consensus_reexports.yml

@@ -0,0 +1,6 @@
+project: cardano-api
+pr: 1232
+kind:
+  - compatible
+description: |
+  Re-export consensus types from Cardano.Api.Consensus for node kernel access: NodeKernel, ChainDB, BlockComponent, RealPoint, OneEraHash, HeaderHash, HasHeader, BlockType, StandardCrypto, CardanoBlock, blockNo.

.changes/20260602_cardano_rpc_fetchblock.yml

@@ -0,0 +1,6 @@
+project: cardano-rpc
+pr: 1232
+kind:
+  - feature
+description: |
+  Implement FetchBlock SyncService method via node kernel access. Fetches blocks from ChainDB with raw CBOR bytes and cardano block header (slot, hash, height).

.gitignore

@@ -85,3 +85,4 @@ cardano-wasm/examples/*/main.js
 cardano-wasm/examples/*/cardano_node_grpc_web_pb.js
 .ghc-wasm/
 
+.serena/

cardano-api/src/Cardano/Api/Consensus.hs

@@ -47,14 +47,25 @@ module Cardano.Api.Consensus
   , ProtocolClientInfoArgs (..)
 
     -- * Reexports from @ouroboros-consensus@
+  , BlockComponent (..)
   , ByronBlock
+  , CardanoBlock
+  , ChainDB.ChainDB
+  , ChainDB.getBlockComponent
   , ChainDepState
   , GenTx (..)
   , EraMismatch (..)
+  , HasHeader
+  , HeaderHash
+  , NodeKernel (..)
+  , OneEraHash (..)
   , PastHorizonException
   , PraosProtocolSupportsNode
   , PraosProtocolSupportsNodeCrypto
+  , RealPoint (..)
   , ShelleyGenesisStaking (..)
+  , StandardCrypto
+  , blockNo
   , byronIdTx
   , condense
   , getOpCertCounters
@@ -68,3 +79,5 @@ import Cardano.Api.Consensus.Internal.InMode
 import Cardano.Api.Consensus.Internal.Mode
 import Cardano.Api.Consensus.Internal.Protocol
 import Cardano.Api.Consensus.Internal.Reexport
+
+import Ouroboros.Consensus.Storage.ChainDB qualified as ChainDB

cardano-api/src/Cardano/Api/Consensus/Internal/Reexport.hs

@@ -1,12 +1,21 @@
 module Cardano.Api.Consensus.Internal.Reexport
-  ( ByronBlock
+  ( BlockComponent (..)
+  , ByronBlock
+  , CardanoBlock
   , ChainDepState
   , GenTx (..)
+  , HasHeader
+  , HeaderHash
   , EraMismatch (..)
+  , NodeKernel (..)
+  , OneEraHash (..)
   , PastHorizonException
   , PraosProtocolSupportsNode
   , PraosProtocolSupportsNodeCrypto
+  , RealPoint (..)
   , ShelleyGenesisStaking (..)
+  , StandardCrypto
+  , blockNo
   , byronIdTx
   , condense
   , getOpCertCounters
@@ -16,19 +25,24 @@ module Cardano.Api.Consensus.Internal.Reexport
   )
 where
 
+import Cardano.Protocol.Crypto (StandardCrypto)
+import Ouroboros.Consensus.Block (HasHeader, HeaderHash, RealPoint (..), blockNo)
 import Ouroboros.Consensus.Byron.Ledger (ByronBlock, GenTx (..), byronIdTx)
-import Ouroboros.Consensus.Cardano.Block (EraMismatch (..))
+import Ouroboros.Consensus.Cardano.Block (CardanoBlock, EraMismatch (..))
+import Ouroboros.Consensus.HardFork.Combinator.AcrossEras (OneEraHash (..))
 import Ouroboros.Consensus.HardFork.History.EpochInfo (interpreterToEpochInfo)
 import Ouroboros.Consensus.HardFork.History.Qry
   ( PastHorizonException
   , unsafeExtendSafeZone
   )
 import Ouroboros.Consensus.Ledger.SupportsMempool (txId)
+import Ouroboros.Consensus.Node (NodeKernel (..))
 import Ouroboros.Consensus.Protocol.Abstract (ChainDepState)
 import Ouroboros.Consensus.Protocol.Praos.Common
   ( PraosProtocolSupportsNode
   , PraosProtocolSupportsNodeCrypto
   , getOpCertCounters
   )
 import Ouroboros.Consensus.Shelley.Node (ShelleyGenesisStaking (..))
+import Ouroboros.Consensus.Storage.Common (BlockComponent (..))
 import Ouroboros.Consensus.Util.Condense (condense)

cardano-rpc/README.md

@@ -33,7 +33,7 @@ It implements [UTxO RPC](https://utxorpc.org/introduction) protobuf communicatio
 
 | Method | Status |
 |--------|--------|
-| [FetchBlock](https://utxorpc.org/sync/spec/#fetchblockrequest) | ⬜ Not supported |
+| [FetchBlock](https://utxorpc.org/sync/spec/#fetchblockrequest) | 🚧 In progress (missing: `Block.timestamp`, `Block.body.tx`) |
 | [DumpHistory](https://utxorpc.org/sync/spec/#dumphistoryrequest) | ⬜ Not supported |
 | [FollowTip](https://utxorpc.org/sync/spec/#followtiprequest) | ⬜ Not supported |
 | [ReadTip](https://utxorpc.org/sync/spec/#readtiprequest) | ⬜ Not supported |

cardano-rpc/cardano-rpc.cabal

@@ -51,6 +51,7 @@ library
     Cardano.Rpc.Proto.Api.Node
     Cardano.Rpc.Proto.Api.UtxoRpc.Query
     Cardano.Rpc.Proto.Api.UtxoRpc.Submit
+    Cardano.Rpc.Proto.Api.UtxoRpc.Sync
     Cardano.Rpc.Server
     Cardano.Rpc.Server.Config
     Cardano.Rpc.Server.Internal.Env
@@ -62,7 +63,10 @@ library
     Cardano.Rpc.Server.Internal.UtxoRpc.Predicate
     Cardano.Rpc.Server.Internal.UtxoRpc.Query
     Cardano.Rpc.Server.Internal.UtxoRpc.Submit
+    Cardano.Rpc.Server.Internal.UtxoRpc.Sync
     Cardano.Rpc.Server.Internal.UtxoRpc.Type
+    Cardano.Rpc.Server.NodeKernelAccess
+    Cardano.Rpc.Server.NodeKernelAccess.Internal
 
   other-modules:
     Cardano.Rpc.Server.Internal.Orphans
@@ -111,6 +115,8 @@ library gen
     Proto.Utxorpc.V1beta.Query.Query_Fields
     Proto.Utxorpc.V1beta.Submit.Submit
     Proto.Utxorpc.V1beta.Submit.Submit_Fields
+    Proto.Utxorpc.V1beta.Sync.Sync
+    Proto.Utxorpc.V1beta.Sync.Sync_Fields
 
   build-depends:
     proto-lens-protobuf-types,