diff --git a/Cargo.lock b/Cargo.lock
index 6a83b3a82bc..fb0b4f85cde 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1132,6 +1132,7 @@ dependencies = [
  "async-trait",
  "mockall",
  "serde",
+ "starknet-types-core",
  "starknet_api",
  "starknet_committer",
  "strum",
@@ -12559,7 +12560,10 @@ dependencies = [
  "apollo_config",
  "async-recursion",
  "async-trait",
+ "bincode 1.3.3",
+ "blake2",
  "derive_more",
+ "digest 0.10.7",
  "ethnum",
  "expect-test",
  "hex",
diff --git a/crates/apollo_committer/Cargo.toml b/crates/apollo_committer/Cargo.toml
index e2f536c9cec..fce52d7cbc3 100644
--- a/crates/apollo_committer/Cargo.toml
+++ b/crates/apollo_committer/Cargo.toml
@@ -8,6 +8,7 @@ description = "State root commitment computation component for the Starknet sequ
 
 [features]
 testing = []
+os_input = ["apollo_committer_types/os_input"]
 
 [dependencies]
 apollo_committer_config.workspace = true
@@ -16,7 +17,7 @@ apollo_infra.workspace = true
 apollo_metrics.workspace = true
 async-trait.workspace = true
 starknet_api.workspace = true
-starknet_committer.workspace = true
+starknet_committer = { workspace = true, features = ["os_input"] }
 starknet_patricia_storage = { workspace = true, features = ["rocksdb_storage"] }
 tracing.workspace = true
 
diff --git a/crates/apollo_committer/src/communication.rs b/crates/apollo_committer/src/communication.rs
index 4c8c44cf4d8..a4020ba572d 100644
--- a/crates/apollo_committer/src/communication.rs
+++ b/crates/apollo_committer/src/communication.rs
@@ -2,7 +2,15 @@ use apollo_committer_types::communication::{CommitterRequest, CommitterResponse}
 use apollo_infra::component_definitions::ComponentRequestHandler;
 use apollo_infra::component_server::{LocalComponentServer, RemoteComponentServer};
 use async_trait::async_trait;
-use starknet_committer::db::forest_trait::ForestStorageWithEmptyReadContext;
+#[cfg(feature = "os_input")]
+use starknet_committer::db::forest_trait::ForestStorageWithWitnesses;
+#[cfg(not(feature = "os_input"))]
+use starknet_committer::db::forest_trait::{
+    ForestStorageWithEmptyReadContext,
+    ForestWriterWithMetadataAndWitnesses,
+};
+#[cfg(feature = "os_input")]
+use starknet_patricia_storage::storage_trait::ImmutableReadOnlyStorage;
 
 use crate::committer::{ApolloCommitter, Committer, StorageConstructor};
 
@@ -10,9 +18,12 @@ pub type LocalCommitterServer =
     LocalComponentServer<ApolloCommitter, CommitterRequest, CommitterResponse>;
 pub type RemoteCommitterServer = RemoteComponentServer<CommitterRequest, CommitterResponse>;
 
+#[cfg(not(feature = "os_input"))]
 #[async_trait]
-impl<S: StorageConstructor, ForestDB: ForestStorageWithEmptyReadContext<Storage = S>>
-    ComponentRequestHandler<CommitterRequest, CommitterResponse> for Committer<S, ForestDB>
+impl<S: StorageConstructor, ForestDB> ComponentRequestHandler<CommitterRequest, CommitterResponse>
+    for Committer<S, ForestDB>
+where
+    ForestDB: ForestStorageWithEmptyReadContext<Storage = S> + ForestWriterWithMetadataAndWitnesses,
 {
     async fn handle_request(&mut self, request: CommitterRequest) -> CommitterResponse {
         match request {
@@ -25,3 +36,28 @@ impl<S: StorageConstructor, ForestDB: ForestStorageWithEmptyReadContext<Storage
         }
     }
 }
+
+#[cfg(feature = "os_input")]
+#[async_trait]
+impl<S, ForestDB> ComponentRequestHandler<CommitterRequest, CommitterResponse>
+    for Committer<S, ForestDB>
+where
+    S: StorageConstructor + ImmutableReadOnlyStorage + 'static,
+    ForestDB: ForestStorageWithWitnesses<Storage = S>,
+{
+    async fn handle_request(&mut self, request: CommitterRequest) -> CommitterResponse {
+        match request {
+            CommitterRequest::CommitBlock(commit_block_request) => {
+                CommitterResponse::CommitBlock(self.commit_block(commit_block_request).await)
+            }
+            CommitterRequest::RevertBlock(revert_block_request) => {
+                CommitterResponse::RevertBlock(self.revert_block(revert_block_request).await)
+            }
+            CommitterRequest::ReadPathsAndCommitBlock(req) => {
+                CommitterResponse::ReadPathsAndCommitBlock(
+                    self.read_paths_and_commit_block(req).await,
+                )
+            }
+        }
+    }
+}
diff --git a/crates/apollo_committer_types/src/communication.rs b/crates/apollo_committer_types/src/communication.rs
index c18aacfbed7..9b1f1af30a4 100644
--- a/crates/apollo_committer_types/src/communication.rs
+++ b/crates/apollo_committer_types/src/communication.rs
@@ -21,6 +21,8 @@ use crate::committer_types::{
     RevertBlockRequest,
     RevertBlockResponse,
 };
+#[cfg(feature = "os_input")]
+use crate::committer_types::{ReadPathsAndCommitBlockRequest, ReadPathsAndCommitBlockResponse};
 use crate::errors::{CommitterClientError, CommitterClientResult, CommitterResult};
 
 pub type LocalCommitterClient = LocalComponentClient<CommitterRequest, CommitterResponse>;
@@ -43,6 +45,14 @@ pub trait CommitterClient: Send + Sync {
         &self,
         input: RevertBlockRequest,
     ) -> CommitterClientResult<RevertBlockResponse>;
+
+    #[cfg(feature = "os_input")]
+    /// Applies the state diff, collects merged Patricia witnesses for OS input, and persists replay
+    /// data (digest + payload).
+    async fn read_paths_and_commit_block(
+        &self,
+        input: ReadPathsAndCommitBlockRequest,
+    ) -> CommitterClientResult<ReadPathsAndCommitBlockResponse>;
 }
 
 #[derive(Serialize, Deserialize, Clone, AsRefStr, EnumDiscriminants)]
@@ -54,6 +64,8 @@ pub trait CommitterClient: Send + Sync {
 pub enum CommitterRequest {
     CommitBlock(CommitBlockRequest),
     RevertBlock(RevertBlockRequest),
+    #[cfg(feature = "os_input")]
+    ReadPathsAndCommitBlock(ReadPathsAndCommitBlockRequest),
 }
 
 impl_debug_for_infra_requests_and_responses!(CommitterRequest);
@@ -64,6 +76,8 @@ impl PrioritizedRequest for CommitterRequest {}
 pub enum CommitterResponse {
     CommitBlock(CommitterResult<CommitBlockResponse>),
     RevertBlock(CommitterResult<RevertBlockResponse>),
+    #[cfg(feature = "os_input")]
+    ReadPathsAndCommitBlock(CommitterResult<ReadPathsAndCommitBlockResponse>),
 }
 
 impl_debug_for_infra_requests_and_responses!(CommitterResponse);
@@ -109,4 +123,21 @@ where
             Direct
         )
     }
+
+    #[cfg(feature = "os_input")]
+    async fn read_paths_and_commit_block(
+        &self,
+        input: ReadPathsAndCommitBlockRequest,
+    ) -> CommitterClientResult<ReadPathsAndCommitBlockResponse> {
+        let request = CommitterRequest::ReadPathsAndCommitBlock(input);
+        handle_all_response_variants!(
+            self,
+            request,
+            CommitterResponse,
+            ReadPathsAndCommitBlock,
+            CommitterClientError,
+            CommitterError,
+            Direct
+        )
+    }
 }