diff --git a/Cargo.lock b/Cargo.lock
index d71cb1e..fae5064 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -69,6 +69,25 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
+[[package]]
+name = "flatbuffers"
+version = "25.9.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09b6620799e7340ebd9968d2e0708eb82cf1971e9a16821e2091b6d6e475eed5"
+dependencies = [
+ "bitflags",
+ "rustc_version",
+]
+
+[[package]]
+name = "flatc-rust"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57e61227926ef5b237af48bee74394cc4a5a221ebd10c5147a98e612f207851d"
+dependencies = [
+ "log",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.3.4"
@@ -256,6 +275,8 @@ dependencies = [
 name = "protosol"
 version = "2.0.0"
 dependencies = [
+ "flatbuffers",
+ "flatc-rust",
  "prost",
  "prost-build",
 ]
@@ -304,6 +325,15 @@ version = "0.8.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7a2d987857b319362043e95f5353c0535c1f58eec5336fdfcf626430af7def58"
 
+[[package]]
+name = "rustc_version"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfcb3a22ef46e85b45de6ee7e79d063319ebb6594faafcf1c225ea92ab6e9b92"
+dependencies = [
+ "semver",
+]
+
 [[package]]
 name = "rustix"
 version = "0.38.44"
@@ -330,6 +360,12 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "semver"
+version = "1.0.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d767eb0aabc880b29956c35734170f26ed551a859dbd361d140cdbeca61ab1e2"
+
 [[package]]
 name = "syn"
 version = "1.0.109"
diff --git a/Cargo.toml b/Cargo.toml
index 987bdff..b70502e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,8 @@ links = "protosol"
 
 [build-dependencies]
 prost-build = "0.11.9"
+flatc-rust = "0.2.0"
 
 [dependencies]
 prost = "0.11.9"
+flatbuffers = "25.9.23"
diff --git a/build.rs b/build.rs
index b3bb799..60fff15 100644
--- a/build.rs
+++ b/build.rs
@@ -1,4 +1,8 @@
-use std::{env, fs, path::{Path, PathBuf}};
+extern crate flatc_rust;
+use std::{
+    env, fs,
+    path::{Path, PathBuf},
+};
 
 /// Normalize path only on Windows, else just return unchanged.
 fn maybe_normalize_windows_path(path: &Path) -> PathBuf {
@@ -18,34 +22,74 @@ fn maybe_normalize_windows_path(path: &Path) -> PathBuf {
     }
 }
 
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let proto_dir = PathBuf::from("proto");
+fn monitor_and_get_files(
+    dir: &PathBuf,
+    env_var: &str,
+    extension: &str,
+) -> Result<(Vec<PathBuf>, PathBuf), Box<dyn std::error::Error>> {
     let abs = env::current_dir()
         .expect("cwd")
-        .join(&proto_dir)
+        .join(dir)
         .canonicalize()
         .map(|p| maybe_normalize_windows_path(&p))
-        .expect("canonicalize proto dir");
+        .expect("canonicalize dir");
 
     println!("cargo:rerun-if-changed={}", abs.display());
-    println!("cargo:PROTO_DIR={}", abs.display());
+    println!("cargo:{}={}", env_var, abs.display());
 
-    let mut proto_files = vec![];
+    let mut files = vec![];
     for entry in fs::read_dir(&abs)? {
         let path = entry?.path();
-        if path.extension().and_then(|e| e.to_str()) == Some("proto") {
+        if path.extension().and_then(|e| e.to_str()) == Some(extension) {
             println!("cargo:rerun-if-changed={}", path.display());
-            proto_files.push(path);
+            files.push(path);
         }
     }
 
+    Ok((files, abs))
+}
+
+fn compile_protos() -> Result<(), Box<dyn std::error::Error>> {
+    let proto_dir = PathBuf::from("proto");
+    let (proto_files, abs) = monitor_and_get_files(&proto_dir, "PROTO_DIR", "proto")?;
+
     let out_dir = PathBuf::from(env::var("OUT_DIR")?);
     let mut config = prost_build::Config::new();
     config.out_dir(&out_dir);
     config.compile_protos(
-        &proto_files.iter().map(|p| p.display().to_string()).collect::<Vec<_>>(),
+        &proto_files
+            .iter()
+            .map(|p| p.display().to_string())
+            .collect::<Vec<_>>(),
         &[abs],
     )?;
 
     Ok(())
 }
+
+fn compile_flatbuffers() -> Result<(), Box<dyn std::error::Error>> {
+    let flatbuffers_dir = PathBuf::from("flatbuffers");
+    let (flatbuffers_files, abs) =
+        monitor_and_get_files(&flatbuffers_dir, "FLATBUFFERS_DIR", "fbs")?;
+
+    let out_dir = PathBuf::from(env::var("OUT_DIR")?);
+    flatc_rust::run(flatc_rust::Args {
+        lang: "rust",
+        inputs: flatbuffers_files
+            .iter()
+            .map(|p| p.as_path())
+            .collect::<Vec<_>>()
+            .as_slice(),
+        out_dir: out_dir.as_path(),
+        includes: &[abs.as_path()],
+        ..Default::default()
+    })?;
+
+    Ok(())
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    compile_protos()?;
+    compile_flatbuffers()?;
+    Ok(())
+}
diff --git a/flatbuffers/block.fbs b/flatbuffers/block.fbs
new file mode 100644
index 0000000..eaa33da
--- /dev/null
+++ b/flatbuffers/block.fbs
@@ -0,0 +1,84 @@
+// Generated from block.proto
+
+include "metadata.fbs";
+include "context.fbs";
+include "txn.fbs";
+
+namespace org.solana.sealevel.v2;
+
+table CostTracker {
+  block_cost:ulong;
+  vote_cost:ulong;
+}
+
+table Inflation {
+  initial:double;
+  terminal:double;
+  taper:double;
+  foundation:double;
+  foundation_term:double;
+}
+
+table FeeRateGovernor {
+  target_lamports_per_signature:ulong;
+  target_signatures_per_slot:ulong;
+  min_lamports_per_signature:ulong;
+  max_lamports_per_signature:ulong;
+  burn_percent:ubyte;
+}
+
+table BankFields {
+  block_height:ulong;
+  poh:Hash (required);
+  parent_bank_hash:Hash (required);
+  parent_lthash:LtHash (required);
+  current_slot:ulong;
+  parent_slot:ulong;
+  prev_lps:ulong;
+  fee_rate_governor:FeeRateGovernor (required);
+  parent_signature_count:ulong;
+  hashes_per_tick:ulong;
+  ticks_per_slot:ulong;
+  slots_per_year:double;
+  inflation:Inflation (required);
+  genesis_creation_time:ulong;
+  prev_epoch_capitalization:ulong;
+  vote_accounts_t_1:[VoteAccount] (required);
+  vote_accounts_t_2:[VoteAccount] (required);
+}
+
+struct LeaderScheduleHash {
+  hash:[ubyte:16];
+}
+
+table LeaderScheduleEffects {
+  leaders_epoch:ulong;
+  leaders_slot0:ulong;
+  leaders_slot_cnt:ulong;
+  leader_pub_cnt:ulong;
+  leaders_sched_cnt:ulong;
+  leader_schedule_hash:LeaderScheduleHash (required);
+}
+
+table BlockContext {
+  transactions:[TransactionMessage] (required);
+  account_states:[Account] (required);
+  blockhash_queue:[Hash] (required);
+  bank_fields:BankFields (required);
+  features:FeatureSet;
+}
+
+table BlockEffects {
+  has_err:bool;
+  slot_capitalization:ulong;
+  bank_hash:Hash;
+  cost_tracker:CostTracker;
+  leader_schedule:LeaderScheduleEffects;
+}
+
+table BlockFixture {
+  metadata:FixtureMetadata (required);
+  input:BlockContext (required);
+  output:BlockEffects (required);
+}
+
diff --git a/flatbuffers/context.fbs b/flatbuffers/context.fbs
new file mode 100644
index 0000000..8c61227
--- /dev/null
+++ b/flatbuffers/context.fbs
@@ -0,0 +1,36 @@
+// Generated from context.proto
+
+namespace org.solana.sealevel.v2;
+
+struct Pubkey {
+  address:[ubyte:32];
+}
+
+struct Signature {
+  signature:[ubyte:64];
+}
+
+struct Hash {
+  hash:[ubyte:32];
+}
+
+struct LtHash {
+  hash:[ushort:1024];
+}
+
+table FeatureSet {
+  features:[ulong];
+}
+
+table Account {
+  address:Pubkey (required);
+  lamports:ulong;
+  data:[ubyte] (required);
+  executable:bool;
+  owner:Pubkey (required);
+}
+
+table VoteAccount {
+  vote_account:Account (required);
+  stake:ulong;
+}
diff --git a/flatbuffers/elf.fbs b/flatbuffers/elf.fbs
new file mode 100644
index 0000000..7e36ee9
--- /dev/null
+++ b/flatbuffers/elf.fbs
@@ -0,0 +1,28 @@
+// Generated from elf.proto
+
+include "metadata.fbs";
+include "context.fbs";
+
+namespace org.solana.sealevel.v2;
+
+table ELFLoaderCtx {
+  elf_data:[ubyte] (required);
+  features:FeatureSet (required);
+  deploy_checks:bool;
+}
+
+table ELFLoaderEffects {
+  err_code:ubyte;
+  rodata_hash:ulong;
+  text_cnt:ulong;
+  text_off:ulong;
+  entry_pc:ulong;
+  calldests_hash:ulong;
+}
+
+table ELFLoaderFixture {
+  metadata:FixtureMetadata (required);
+  input:ELFLoaderCtx (required);
+  output:ELFLoaderEffects (required);
+}
+
diff --git a/flatbuffers/instr.fbs b/flatbuffers/instr.fbs
new file mode 100644
index 0000000..ab999b9
--- /dev/null
+++ b/flatbuffers/instr.fbs
@@ -0,0 +1,36 @@
+// Generated from invoke.proto
+
+include "metadata.fbs";
+include "context.fbs";
+
+namespace org.solana.sealevel.v2;
+
+table InstrAccount {
+  index:ubyte;
+  is_writable:bool;
+  is_signer:bool;
+}
+
+table InstrContext {
+  program_id:Pubkey (required);
+  account_states:[Account] (required);
+  instr_accounts:[InstrAccount] (required);
+  instr_data:[ubyte] (required);
+  cu_avail:ulong;
+  features:FeatureSet;
+}
+
+table InstrEffects {
+  err_code:ubyte;
+  custom_err_code:uint;
+  modified_accounts:[Account];
+  cu_remaining:ulong;
+  return_data:[ubyte];
+}
+
+table InstrFixture {
+  metadata:FixtureMetadata (required);
+  input:InstrContext (required);
+  output:InstrEffects (required);
+}
+
diff --git a/flatbuffers/metadata.fbs b/flatbuffers/metadata.fbs
new file mode 100644
index 0000000..92450aa
--- /dev/null
+++ b/flatbuffers/metadata.fbs
@@ -0,0 +1,8 @@
+// Generated from metadata.proto
+
+namespace org.solana.sealevel.v2;
+
+table FixtureMetadata {
+  fn_entrypoint:string (required);
+}
+
diff --git a/flatbuffers/txn.fbs b/flatbuffers/txn.fbs
new file mode 100644
index 0000000..8ef15bb
--- /dev/null
+++ b/flatbuffers/txn.fbs
@@ -0,0 +1,66 @@
+// Generated from txn.proto
+
+include "metadata.fbs";
+include "context.fbs";
+
+namespace org.solana.sealevel.v2;
+
+table MessageHeader {
+  num_required_signatures:ubyte;
+  num_readonly_signed_accounts:ubyte;
+  num_readonly_unsigned_accounts:ubyte;
+}
+
+table CompiledInstruction {
+  program_id_index:ubyte;
+  accounts:[ubyte] (required);
+  data:[ubyte] (required);
+}
+
+table AddressLookupTable {
+  account_key:Pubkey (required);
+  writable_indexes:[ubyte] (required);
+  readonly_indexes:[ubyte] (required);
+}
+
+table TransactionMessage {
+  is_legacy:bool;
+  header:MessageHeader (required);
+  account_keys:[Pubkey] (required);
+  recent_blockhash:Hash (required);
+  instructions:[CompiledInstruction] (required);
+  address_lookup_tables:[AddressLookupTable] (required);
+  message_hash:Hash (required);
+  signatures:[Signature] (required);
+}
+
+table TxnContext {
+  txn_message:TransactionMessage (required);
+  account_states:[Account] (required);
+  blockhash_queue:[Hash] (required);
+  features:FeatureSet;
+}
+
+table FeeDetails {
+  transaction_fee:ulong;
+  prioritization_fee:ulong;
+}
+
+table TxnEffects {
+  txn_err_code:ubyte;
+  instr_err_code:ubyte;
+  instr_err_idx:ubyte;
+  custom_err_code:uint;
+  modified_accounts:[Account];
+  return_data:[ubyte];
+  executed_units:ulong;
+  fee_details:FeeDetails;
+  loaded_accounts_data_size:uint;
+}
+
+table TxnFixture {
+  metadata:FixtureMetadata (required);
+  input:TxnContext (required);
+  output:TxnEffects (required);
+}
+
diff --git a/flatbuffers/vm.fbs b/flatbuffers/vm.fbs
new file mode 100644
index 0000000..2824bfd
--- /dev/null
+++ b/flatbuffers/vm.fbs
@@ -0,0 +1,90 @@
+// Generated from vm.proto
+
+include "metadata.fbs";
+include "context.fbs";
+include "instr.fbs";
+
+namespace org.solana.sealevel.v2;
+
+enum ErrKind : ubyte {
+  UNSPECIFIED = 0,
+  EBPF = 1,
+  SYSCALL = 2,
+  INSTRUCTION = 3,
+}
+
+table InputDataRegion {
+  offset:ulong;
+  content:[ubyte] (required);
+  is_writable:bool;
+}
+
+table VmContext {
+  heap_max:ulong;
+  rodata:[ubyte] (required);
+  rodata_text_section_offset:ulong;
+  rodata_text_section_length:ulong;
+  r0:ulong;
+  r1:ulong;
+  r2:ulong;
+  r3:ulong;
+  r4:ulong;
+  r5:ulong;
+  r6:ulong;
+  r7:ulong;
+  r8:ulong;
+  r9:ulong;
+  r10:ulong;
+  r11:ulong;
+  entry_pc:ulong;
+  calldests:[ubyte] (required);
+  return_data:ReturnData;
+  sbpf_version:ubyte;
+}
+
+table ReturnData {
+  program_id:Pubkey (required);
+  data:[ubyte] (required);
+}
+
+table SyscallInvocation {
+  function_name:string (required);
+  heap_prefix:[ubyte] (required);
+  stack_prefix:[ubyte] (required);
+}
+
+table SyscallContext {
+  vm_ctx:VmContext (required);
+  instr_ctx:InstrContext (required);
+  syscall_invocation:SyscallInvocation (required);
+}
+
+table SyscallEffects {
+  err_code:byte;
+  err_kind:ErrKind;
+  cu_avail:ulong;
+  heap:[ubyte];
+  stack:[ubyte];
+  input_data_regions:[InputDataRegion];
+  frame_count:ulong;
+  log:string;
+  rodata:[ubyte];
+  pc:ulong;
+  r0:ulong;
+  r1:ulong;
+  r2:ulong;
+  r3:ulong;
+  r4:ulong;
+  r5:ulong;
+  r6:ulong;
+  r7:ulong;
+  r8:ulong;
+  r9:ulong;
+  r10:ulong;
+}
+
+table SyscallFixture {
+  metadata:FixtureMetadata (required);
+  input:SyscallContext (required);
+  output:SyscallEffects (required);
+}