diff --git a/Cargo.lock b/Cargo.lock
index 789ae78..3f75dc6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -97,9 +97,9 @@ checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
 [[package]]
 name = "alloy"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f07ea118327e6ff9a1cba5ae26c0a9a9744bec1dd6734ed75b5b46fc9be6d077"
+checksum = "c62f44203459c0fdeae67338c2b264c761c614d460feca0b0a230058435e3c1d"
 dependencies = [
  "alloy-consensus",
  "alloy-contract",
@@ -139,9 +139,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-consensus"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86debde32d8dbb0ab29e7cc75ae1a98688ac7a4c9da54b3a9b14593b9b3c46d3"
+checksum = "c622b1418d86afba7116e2617280859d4a2737e06e6e4dd4694a7a96ae8aff79"
 dependencies = [
  "alloy-eips",
  "alloy-primitives",
@@ -167,9 +167,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-consensus-any"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d6cb2e7efd385b333f5a77b71baaa2605f7e22f1d583f2879543b54cbce777c"
+checksum = "90eeb45e8554a35ade97344552df4f6cdb000a53da955916f573b1998a81f791"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -182,9 +182,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-contract"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "668859fcdb42eee289de22a9d01758c910955bb6ecda675b97276f99ce2e16b0"
+checksum = "363d9d618d98952b07e50defdf3f8bc59ae24b7ba6161397a2e380370fd3ebf3"
 dependencies = [
  "alloy-consensus",
  "alloy-dyn-abi",
@@ -296,9 +296,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-eips"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "be47bf1b91674a5f394b9ed3c691d764fb58ba43937f1371550ff4bc8e59c295"
+checksum = "2cbd6558e8a2fe9de811faae7ccc0b3d2a4c71b1cd77e57e5c89cba20693420b"
 dependencies = [
  "alloy-eip2124",
  "alloy-eip2930",
@@ -344,9 +344,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-genesis"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a59f6f520c323111650d319451de1edb1e32760029a468105b9d7b0f7c11bdf2"
+checksum = "91dd00b84d8c9b9fd055254a147e4521cca0a8f19da808fd3376e4bd6f292d43"
 dependencies = [
  "alloy-eips",
  "alloy-primitives",
@@ -398,9 +398,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-json-rpc"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a24c81a56d684f525cd1c012619815ad3a1dd13b0238f069356795d84647d3c"
+checksum = "95ae5cbb425b6e72f99e24860506809e4908113b76ede8de1333996edccbf38c"
 dependencies = [
  "alloy-primitives",
  "alloy-sol-types",
@@ -413,9 +413,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-network"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "786c5b3ad530eaf43cda450f973fe7fb1c127b4c8990adf66709dafca25e3f6f"
+checksum = "5abea24fba6bfb859954d1ebfaaebf77886b802ec559cbe7fd16f992a31d41ec"
 dependencies = [
  "alloy-consensus",
  "alloy-consensus-any",
@@ -439,9 +439,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-network-primitives"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1ed40adf21ae4be786ef5eb62db9c692f6a30f86d34452ca3f849d6390ce319"
+checksum = "905f7628888eed587274dbea536168f64f6a401b377cd77b9fe91866ce1478a0"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -452,9 +452,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-node-bindings"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0f15cffc63c421d33d77f6d30d7d18ef090a44ecf32205f5bfa12d4e565360a"
+checksum = "d60ff34bfb17d2401381b8f177257bcda467d77eb26c7f4084695923d41b5821"
 dependencies = [
  "alloy-genesis",
  "alloy-hardforks 0.2.13",
@@ -505,9 +505,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-provider"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a3ca4c15818be7ac86208aff3a91b951d14c24e1426e66624e75f2215ba5e2cc"
+checksum = "991d0ccc0ed7a1d083e96f251627ad6d551769cff7ad2d07b0d0b335e99cba63"
 dependencies = [
  "alloy-chains",
  "alloy-consensus",
@@ -554,9 +554,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-pubsub"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e9eb9c9371738ac47f589e40aae6e418cb5f7436ad25b87575a7f94a60ccf43b"
+checksum = "295dba19c629c431554f4e2918b43bf02bce7464990631e67304e2a3362d9c3f"
 dependencies = [
  "alloy-json-rpc",
  "alloy-primitives",
@@ -598,9 +598,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-client"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "abe0addad5b8197e851062b49dc47157444bced173b601d91e3f9b561a060a50"
+checksum = "edc1343d06dd354cee121763e7fb243db3b7962d747df0c231ce13c249f48efd"
 dependencies = [
  "alloy-json-rpc",
  "alloy-primitives",
@@ -624,9 +624,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74d17d4645a717f0527e491f44f6f7a75c221b9c00ccf79ddba2d26c8e0df4c3"
+checksum = "03c4079f59cc4753389e2eb0e20cd2a98ddfc58f8bcec33b98d86e8d8c701f82"
 dependencies = [
  "alloy-primitives",
  "alloy-rpc-types-anvil",
@@ -643,9 +643,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-admin"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ded79e60d8fd0d7c851044f8b2f2dd7fa8dfa467c577d620595d4de3c31eff7e"
+checksum = "ebf8f659abddbafb74dab174204aa4e9e2785425bd3899eb948d1d9fae2c9bfd"
 dependencies = [
  "alloy-genesis",
  "alloy-primitives",
@@ -655,9 +655,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-anvil"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2593ce5e1fd416e3b094e7671ef361f22e6944545e0e62ee309b6dfbd702225d"
+checksum = "a816be17cfbcb36a08a8b88bc2157ee1aa2ea258fb2c48a5ba6a3e3729a7f031"
 dependencies = [
  "alloy-primitives",
  "alloy-rpc-types-eth",
@@ -667,9 +667,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-any"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0e98aabb013a71a4b67b52825f7b503e5bb6057fb3b7b2290d514b0b0574b57"
+checksum = "8405d1a23dbd570679196289c9c6ea23e8f3d69f24a9a942002a45bb4b2a844c"
 dependencies = [
  "alloy-consensus-any",
  "alloy-rpc-types-eth",
@@ -678,9 +678,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-beacon"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3a647a4e3acf49182135c2333d6f9b11ab8684559ff43ef1958ed762cfe9fe0e"
+checksum = "645d3eafd5b909d23e6248ecaadbaf66f464db5097a5794615784c1370df12bf"
 dependencies = [
  "alloy-eips",
  "alloy-primitives",
@@ -698,9 +698,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-debug"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2a1dd760b6a798ee045ab6a7bbd1a02ad8bd6a64d8e18d6e41732f4fc4a4fe5c"
+checksum = "4ca2e88ed4e5e88955d5988eb32b9c5483912a3af7936436b0e5f5f3da512880"
 dependencies = [
  "alloy-primitives",
  "derive_more",
@@ -710,9 +710,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-engine"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ddc871ae69688e358cf242a6a7ee6b6e0476a03fd0256434c68daedaec086ec4"
+checksum = "fc7bf1ae6bf74b82e033888db62466cde2cd279ca9ff601b601f5b315314fb4e"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -731,9 +731,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-eth"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5899af8417dcf89f40f88fa3bdb2f3f172605d8e167234311ee34811bbfdb0bf"
+checksum = "9be559930a667c9343b1f21179be4f1a5a345c8caf7ef506eb216ad507de4ffb"
 dependencies = [
  "alloy-consensus",
  "alloy-consensus-any",
@@ -753,9 +753,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-mev"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4d4c9229424e77bd97e629fba44dbfdadebe5bfadbb1e53ad4acbc955610b6c7"
+checksum = "da494d19924be84bbeeacd1c77ce117b67f8db46fd784a046db2cc26f3ffa407"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -768,9 +768,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-trace"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "410a80e9ac786a2d885adfd7da3568e8f392da106cb5432f00eb4787689d281a"
+checksum = "2fc955f47f331437ee9072a486088bdd2ee8230eea4df059566108fc900896ca"
 dependencies = [
  "alloy-primitives",
  "alloy-rpc-types-eth",
@@ -782,9 +782,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-txpool"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3a8074654c0292783d504bfa1f2691a69f420154ee9a7883f9212eaf611e60cd"
+checksum = "3820522d80137bac38db35ad7af40c275fdce107c7ba25fd94659b53e3d46768"
 dependencies = [
  "alloy-primitives",
  "alloy-rpc-types-eth",
@@ -794,9 +794,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-serde"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "feb73325ee881e42972a5a7bc85250f6af89f92c6ad1222285f74384a203abeb"
+checksum = "617076af047ac9ffec0e8a3ef48fccbf6eb9d5aee6b302476346f729e469c804"
 dependencies = [
  "alloy-primitives",
  "arbitrary",
@@ -806,9 +806,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-signer"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1bea4c8f30eddb11d7ab56e83e49c814655daa78ca708df26c300c10d0189cbc"
+checksum = "3540dd7ff91763cd60760438442a10392f8f04f41fb3c4981323f3c34d96ccb2"
 dependencies = [
  "alloy-primitives",
  "async-trait",
@@ -821,9 +821,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-signer-aws"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "51f6ae79701edb2c21b5f9ff007ae0228168b36e5ca25a20873b2db2cda4ad31"
+checksum = "6c9cdc832ab4353af07656e4dfc2c2bc59264a424f90f4a6cee6bd1caa0a8af4"
 dependencies = [
  "alloy-consensus",
  "alloy-network",
@@ -840,9 +840,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-signer-local"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c28bd71507db58477151a6fe6988fa62a4b778df0f166c3e3e1ef11d059fe5fa"
+checksum = "a382f4fc60d1155fa684fe68870e18a265043b0f3a11c7a2b5072447cb5fbafc"
 dependencies = [
  "alloy-consensus",
  "alloy-network",
@@ -932,9 +932,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b321f506bd67a434aae8e8a7dfe5373bf66137c149a5f09c9e7dfb0ca43d7c91"
+checksum = "6ac0e7b6ebe03a97143d0bae318212b876306d669cc9b25071184d2e85877b4a"
 dependencies = [
  "alloy-json-rpc",
  "auto_impl",
@@ -955,12 +955,13 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport-http"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "30bf12879a20e1261cd39c3b101856f52d18886907a826e102538897f0d2b66e"
+checksum = "a19f6f46ab490750059b0d32ce74323ebe7bb6d8137073523dfef754c3af2252"
 dependencies = [
  "alloy-json-rpc",
  "alloy-transport",
+ "itertools 0.14.0",
  "reqwest",
  "serde_json",
  "tower",
@@ -970,9 +971,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport-ipc"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b75f2334d400249e9672a1ec402536bab259e27a66201a94c3c9b3f1d3bae241"
+checksum = "8e0b477248bf29d1a990a10bc8ab494a7f39c3d1720bb1d6c8eae4649a28df56"
 dependencies = [
  "alloy-json-rpc",
  "alloy-pubsub",
@@ -990,9 +991,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport-ws"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "527a0d9c8bbc5c3215b03ad465d4ae8775384ff5faec7c41f033f087c851a9f9"
+checksum = "4feacef4309079e77763aaa6581090c748500a56faae3edb5928464ec3c0f769"
 dependencies = [
  "alloy-pubsub",
  "alloy-transport",
@@ -1028,9 +1029,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-tx-macros"
-version = "1.6.1"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a91d6b4c2f6574fdbcb1611e460455c326667cf5b805c6bd1640dad8e8ee4d2"
+checksum = "5f5bfa1887d55418bd22c922c5ae679f2c0dbda5cba03d1300bd7299e9602350"
 dependencies = [
  "darling 0.21.3",
  "proc-macro2",
@@ -4949,9 +4950,9 @@ dependencies = [
 
 [[package]]
 name = "init4-bin-base"
-version = "0.18.0-rc.8"
+version = "0.18.0-rc.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "185fbd1b6320603134ec222356f6014806e589a1ef73532882609fa23766b5cd"
+checksum = "9fe89ed003118f165bd3a1a9dc49b25417766b7f52fd87c380d425b8ea0ff60f"
 dependencies = [
  "alloy",
  "async-trait",
@@ -7185,9 +7186,9 @@ dependencies = [
 
 [[package]]
 name = "rapidhash"
-version = "4.2.2"
+version = "4.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "71ec30b38a417407efe7676bad0ca6b78f995f810185ece9af3bd5dc561185a9"
+checksum = "84816e4c99c467e92cf984ee6328caa976dfecd33a673544489d79ca2caaefe5"
 dependencies = [
  "rand 0.9.2",
  "rustversion",
@@ -10543,9 +10544,9 @@ dependencies = [
 
 [[package]]
 name = "ryu"
-version = "1.0.22"
+version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a50f4cf475b65d88e057964e0e9bb1f0aa9bbb2036dc65c64596b42932536984"
+checksum = "9774ba4a74de5f7b1c1451ed6cd5285a32eddb5cccb8cc655a4e50009e06477f"
 
 [[package]]
 name = "ryu-js"
@@ -12289,9 +12290,9 @@ checksum = "dbc4bc3a9f746d862c45cb89d705aa10f187bb96c76001afab07a0d35ce60142"
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.22"
+version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9312f7c4f6ff9069b165498234ce8be658059c6728633667c526e27dc2cf1df5"
+checksum = "537dd038a89878be9b64dd4bd1b260315c1bb94f4d784956b81e27a088d9a09e"
 
 [[package]]
 name = "unicode-segmentation"
@@ -13376,9 +13377,9 @@ dependencies = [
 
 [[package]]
 name = "zmij"
-version = "1.0.19"
+version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ff05f8caa9038894637571ae6b9e29466c1f4f829d26c9b28f869a29cbe3445"
+checksum = "4de98dfa5d5b7fef4ee834d0073d560c9ca7b6c46a71d058c48db7960f8cfaf7"
 
 [[package]]
 name = "zstd"
diff --git a/Cargo.toml b/Cargo.toml
index 43c7034..da5b0eb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,7 @@ name = "zenith-builder-example"
 path = "bin/builder.rs"
 
 [dependencies]
-init4-bin-base = { version = "0.18.0-rc.8", features = ["perms", "aws"] }
+init4-bin-base = { version = "0.18.0-rc.9", features = ["perms", "aws", "pylon"] }
 
 signet-constants = { version = "0.16.0-rc.8" }
 signet-sim = { version = "0.16.0-rc.8" }
diff --git a/src/config.rs b/src/config.rs
index 1296ccc..79c125a 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -12,7 +12,7 @@ use alloy::{
 };
 use eyre::Result;
 use init4_bin_base::{
-    perms::{Authenticator, OAuthConfig, SharedToken},
+    perms::{Authenticator, OAuthConfig, SharedToken, pylon},
     utils::{
         calc::SlotCalculator,
         from_env::FromEnv,
@@ -25,6 +25,9 @@ use signet_zenith::Zenith;
 use std::borrow::Cow;
 use tokio::join;
 
+/// Pylon client type for blob sidecar submission.
+pub type PylonClient = pylon::PylonClient;
+
 /// Type alias for the provider used to simulate against rollup state.
 pub type RuProvider = RootProvider<Ethereum>;
 
@@ -168,6 +171,10 @@ pub struct BuilderConfig {
 
     /// The signet system constants.
     pub constants: SignetSystemConstants,
+
+    /// URL for the Pylon blob server API.
+    #[from_env(var = "PYLON_URL", desc = "URL for the Pylon blob server API")]
+    pub pylon_url: url::Url,
 }
 
 impl BuilderConfig {
@@ -285,4 +292,9 @@ impl BuilderConfig {
         ((gas_limit as u128 * (self.max_host_gas_coefficient.unwrap_or(80) as u128)) / 100u128)
             as u64
     }
+
+    /// Connect to the Pylon blob server.
+    pub fn connect_pylon(&self) -> PylonClient {
+        PylonClient::new(self.pylon_url.clone(), self.oauth_token())
+    }
 }
diff --git a/src/tasks/block/sim.rs b/src/tasks/block/sim.rs
index 3963dc4..ea3cfe3 100644
--- a/src/tasks/block/sim.rs
+++ b/src/tasks/block/sim.rs
@@ -5,7 +5,7 @@ use crate::{
     config::{BuilderConfig, HostProvider, RuProvider},
     tasks::env::SimEnv,
 };
-use alloy::consensus::Header;
+use alloy::{consensus::Header, eips::Encodable2718, primitives::Bytes};
 use init4_bin_base::{
     deps::metrics::{counter, histogram},
     utils::calc::SlotCalculator,
@@ -62,6 +62,21 @@ impl SimResult {
     pub fn clone_span(&self) -> Span {
         self.sim_env.clone_span()
     }
+
+    /// Constructs the MEV bundle body from host transactions and the submission transaction.
+    ///
+    /// Combines all host transactions from the rollup block with the prepared rollup block
+    /// submission transaction, wrapping each as a non-revertible bundle item.
+    ///
+    /// The rollup block transaction is always included and placed last in the bundle.
+    pub fn build_bundle_body(&self, block_tx_bytes: Bytes) -> Vec<Bytes> {
+        self.block
+            .host_transactions()
+            .iter()
+            .map(|tx| tx.encoded_2718().into())
+            .chain(std::iter::once(block_tx_bytes))
+            .collect()
+    }
 }
 
 /// A task that builds blocks based on incoming [`SimEnv`]s and a simulation
diff --git a/src/tasks/cache/bundle.rs b/src/tasks/cache/bundle.rs
index eed8850..7039581 100644
--- a/src/tasks/cache/bundle.rs
+++ b/src/tasks/cache/bundle.rs
@@ -1,6 +1,6 @@
 //! Bundler service responsible for fetching bundles and sending them to the simulator.
 use crate::config::BuilderConfig;
-use init4_bin_base::perms::tx_cache::BuilderTxCache;
+use init4_bin_base::perms::tx_cache::{BuilderTxCache, BuilderTxCacheError};
 use signet_tx_cache::{TxCacheError, types::TxCacheBundle};
 use tokio::{
     sync::mpsc::{UnboundedReceiver, UnboundedSender, unbounded_channel},
@@ -51,7 +51,7 @@ impl BundlePoller {
     }
 
     /// Checks the bundle cache for new bundles.
-    pub async fn check_bundle_cache(&self) -> Result<Vec<TxCacheBundle>, TxCacheError> {
+    pub async fn check_bundle_cache(&self) -> Result<Vec<TxCacheBundle>, BuilderTxCacheError> {
         let res = self.tx_cache.get_bundles(None).await;
 
         match res {
@@ -59,12 +59,12 @@ impl BundlePoller {
                 trace!(count = ?bundles.bundles.len(), "found bundles");
                 Ok(bundles.bundles)
             }
-            Err(TxCacheError::NotOurSlot) => {
-                trace!("Not our slot to fetch bundles");
-                Err(TxCacheError::NotOurSlot)
-            }
             Err(err) => {
-                error!(?err, "Failed to fetch bundles from tx-cache");
+                if matches!(&err, BuilderTxCacheError::TxCache(TxCacheError::NotOurSlot)) {
+                    trace!("Not our slot to fetch bundles");
+                } else {
+                    error!(?err, "Failed to fetch bundles from tx-cache");
+                }
                 Err(err)
             }
         }
diff --git a/src/tasks/submit/flashbots.rs b/src/tasks/submit/flashbots.rs
index 6b3d998..8e70f66 100644
--- a/src/tasks/submit/flashbots.rs
+++ b/src/tasks/submit/flashbots.rs
@@ -1,15 +1,12 @@
 //! Flashbots Task receives simulated blocks from an upstream channel and
 //! submits them to the Flashbots relay as bundles.
 use crate::{
-    config::{BuilderConfig, FlashbotsProvider, HostProvider, ZenithInstance},
+    config::{BuilderConfig, FlashbotsProvider, HostProvider, PylonClient, ZenithInstance},
     quincey::Quincey,
     tasks::{block::sim::SimResult, submit::SubmitPrep},
 };
 use alloy::{
-    consensus::TxEnvelope,
-    eips::Encodable2718,
-    primitives::{Bytes, TxHash},
-    providers::ext::MevApi,
+    consensus::TxEnvelope, eips::Encodable2718, primitives::TxHash, providers::ext::MevApi,
     rpc::types::mev::EthSendBundle,
 };
 use init4_bin_base::{deps::metrics::counter, utils::signer::LocalOrAws};
@@ -32,6 +29,8 @@ pub struct FlashbotsTask {
     signer: LocalOrAws,
     /// Channel for sending hashes of outbound transactions.
     outbound: mpsc::UnboundedSender<TxHash>,
+    /// Pylon client for blob sidecar submission.
+    pylon: PylonClient,
 }
 
 impl FlashbotsTask {
@@ -48,8 +47,9 @@ impl FlashbotsTask {
         )?;
 
         let zenith = config.connect_zenith(host_provider);
+        let pylon = config.connect_pylon();
 
-        Ok(Self { config, quincey, zenith, flashbots, signer: builder_key, outbound })
+        Ok(Self { config, quincey, zenith, flashbots, signer: builder_key, outbound, pylon })
     }
 
     /// Prepares a MEV bundle from a simulation result.
@@ -81,7 +81,7 @@ impl FlashbotsTask {
         let tx_bytes = block_tx.encoded_2718().into();
 
         // Build the bundle body with the block_tx bytes as the last transaction in the bundle.
-        let txs = self.build_bundle_body(sim_result, tx_bytes);
+        let txs = sim_result.build_bundle_body(tx_bytes);
 
         // Create the MEV bundle (valid only in the specific host block)
         Ok(EthSendBundle {
@@ -90,7 +90,6 @@ impl FlashbotsTask {
             ..Default::default()
         })
     }
-
     /// Prepares and signs the submission transaction for the rollup block.
     ///
     /// Creates a `SubmitPrep` instance to build the transaction, then fills
@@ -130,26 +129,6 @@ impl FlashbotsTask {
         }
     }
 
-    /// Constructs the MEV bundle body from host transactions and the submission transaction.
-    ///
-    /// Combines all host transactions from the rollup block with the prepared rollup block
-    /// submission transaction, wrapping each as a non-revertible bundle item.
-    ///
-    /// The rollup block transaction is placed last in the bundle.
-    fn build_bundle_body(
-        &self,
-        sim_result: &SimResult,
-        tx_bytes: alloy::primitives::Bytes,
-    ) -> Vec<Bytes> {
-        sim_result
-            .block
-            .host_transactions()
-            .iter()
-            .map(|tx| tx.encoded_2718().into())
-            .chain(std::iter::once(tx_bytes))
-            .collect()
-    }
-
     /// Main task loop that processes simulation results and submits bundles to Flashbots.
     ///
     /// Receives `SimResult`s from the inbound channel, prepares MEV bundles, and submits
@@ -176,7 +155,6 @@ impl FlashbotsTask {
 
             // Prepare a MEV bundle with the configured call type from the sim result
             let result = self.prepare(&sim_result).instrument(span.clone()).await;
-
             let bundle = match result {
                 Ok(bundle) => bundle,
                 Err(error) => {
@@ -186,6 +164,10 @@ impl FlashbotsTask {
                 }
             };
 
+            // Due to the way the bundle is built, the block transaction is the last transaction in the bundle, and will always exist.
+            // We'll use this to forward the tx to pylon, which will preload the sidecar.
+            let block_tx = bundle.txs.last().unwrap().clone();
+
             // Make a child span to cover submission, or use the current span
             // if debug is not enabled.
             let _guard = span.enter();
@@ -193,9 +175,10 @@ impl FlashbotsTask {
 
             // Send the bundle to Flashbots, instrumenting the send future so
             // all events inside the async send are attributed to the submit
-            // span.
+            // span. If Flashbots accepts it, submit the envelope to Pylon.
             let flashbots = self.flashbots().to_owned();
             let signer = self.signer.clone();
+            let pylon = self.pylon.clone();
 
             tokio::spawn(
                 async move {
@@ -209,6 +192,19 @@ impl FlashbotsTask {
                                 hash = resp.map(|r| r.bundle_hash.to_string()),
                                 "Submitted MEV bundle to Flashbots, received OK response"
                             );
+
+                            match pylon.post_blob_tx(block_tx).await {
+                                Ok(()) => {
+                                    counter!("signet.builder.pylon.sidecars_submitted")
+                                        .increment(1);
+                                    debug!("posted sidecar to pylon");
+                                }
+                                Err(err) => {
+                                    counter!("signet.builder.pylon.submission_failures")
+                                        .increment(1);
+                                    error!(%err, "pylon submission failed");
+                                }
+                            }
                         }
                         Err(err) => {
                             counter!("signet.builder.flashbots.submission_failures").increment(1);
diff --git a/src/test_utils.rs b/src/test_utils.rs
index cb9d3e7..20119f4 100644
--- a/src/test_utils.rs
+++ b/src/test_utils.rs
@@ -56,6 +56,7 @@ pub fn setup_test_config() -> &'static BuilderConfig {
             block_query_cutoff_buffer: 3000,
             max_host_gas_coefficient: Some(80),
             constants: SignetSystemConstants::parmigiana(),
+            pylon_url: "http://localhost:8081".parse().unwrap(),
         }
     })
 }