diff --git a/proto/snapshot.proto b/proto/snapshot.proto
new file mode 100644
index 0000000..7236519
--- /dev/null
+++ b/proto/snapshot.proto
@@ -0,0 +1,109 @@
+syntax = "proto3";
+package org.solana.sealevel.v1;
+import "context.proto";
+import "block.proto";
+import "metadata.proto";
+
+// Snapshot deserialization input with explicit version selection
+message SnapshotContext {
+  // Snapshot format version (e.g. maps to DeserializableVersionedBank variants)
+  uint64 version = 1;
+
+  // Raw serialized snapshot bank data (bincode)
+  bytes data = 2;
+}
+
+message HardFork {
+  uint64 slot = 1;
+  uint64 count = 2;
+}
+
+message RentCollector {
+  uint64 epoch = 1;
+  EpochSchedule epoch_schedule = 2;
+  double slots_per_year = 3;
+  Rent rent = 4;
+}
+
+// Deserialized snapshot bank fields for comparison.
+// Mirrors DeserializableVersionedBank (Agave) / fd_snapshot_manifest (Firedancer).
+message SnapshotEffects {
+  int32 result = 1;
+
+  // Blockhash queue (ordered from oldest to newest, up to 301 entries)
+  repeated BlockhashQueueEntry blockhash_queue = 2;
+
+  // Ancestor slots (being removed in Agave v4.0 reads, zeroed in v4.1)
+  repeated uint64 ancestors = 3;
+
+  // Bank hash (32 bytes)
+  bytes hash = 4;
+
+  // Parent bank hash (32 bytes)
+  bytes parent_hash = 5;
+
+  uint64 parent_slot = 6;
+
+  repeated HardFork hard_forks = 7;
+
+  uint64 transaction_count = 8;
+
+  uint64 tick_height = 9;
+
+  uint64 signature_count = 10;
+
+  uint64 capitalization = 11;
+
+  uint64 max_tick_height = 12;
+
+  // None encoded as 0 with has_hashes_per_tick = false
+  bool has_hashes_per_tick = 13;
+  uint64 hashes_per_tick = 14;
+
+  uint64 ticks_per_slot = 15;
+
+  // uint128 encoded as 16 bytes little-endian
+  bytes ns_per_slot = 16;
+
+  int64 genesis_creation_time = 17;
+
+  double slots_per_year = 18;
+
+  uint64 accounts_data_len = 19;
+
+  uint64 slot = 20;
+
+  // Being removed in Agave v4.0 reads, zeroed in v4.1
+  uint64 epoch = 21;
+
+  uint64 block_height = 22;
+
+  // Collector pubkey (32 bytes)
+  bytes collector_id = 23;
+
+  // Being removed in Agave v4.0 reads, zeroed in v4.1
+  uint64 collector_fees = 24;
+
+  FeeRateGovernor fee_rate_governor = 25;
+
+  // Being removed in Agave v4.0 reads, zeroed in v4.1
+  RentCollector rent_collector = 26;
+
+  EpochSchedule epoch_schedule = 27;
+
+  Inflation inflation = 28;
+
+  repeated StakeDelegation stake_delegations = 29;
+
+  repeated PrevVoteAccount vote_accounts = 30;
+
+  bool is_delta = 31;
+
+  uint64 lamports_per_signature = 32;
+}
+
+message SnapshotFixture {
+  FixtureMetadata metadata = 1;
+  SnapshotContext input = 2;
+  SnapshotEffects output = 3;
+}