diff --git a/crates/starknet_transaction_prover/src/server/rpc_impl.rs b/crates/starknet_transaction_prover/src/server/rpc_impl.rs
index 71eb158b02f..231cde7aee6 100644
--- a/crates/starknet_transaction_prover/src/server/rpc_impl.rs
+++ b/crates/starknet_transaction_prover/src/server/rpc_impl.rs
@@ -17,6 +17,10 @@ use crate::server::config::ServiceConfig;
 use crate::server::errors::{internal_server_error, service_busy};
 use crate::server::rpc_api::ProvingRpcServer;
 
+#[cfg(test)]
+#[path = "rpc_impl_test.rs"]
+mod rpc_impl_test;
+
 /// Starknet RPC specification version (matches the pinned `starknet_specs_rev`).
 pub(crate) const SPEC_VERSION: &str = "0.10.3-rc.2";
 
diff --git a/crates/starknet_transaction_prover/src/server/rpc_impl_test.rs b/crates/starknet_transaction_prover/src/server/rpc_impl_test.rs
new file mode 100644
index 00000000000..351ca01d2d5
--- /dev/null
+++ b/crates/starknet_transaction_prover/src/server/rpc_impl_test.rs
@@ -0,0 +1,85 @@
+use std::time::Duration;
+
+use blockifier_reexecution::state_reader::rpc_objects::BlockId;
+use starknet_api::invoke_tx_args;
+use starknet_api::rpc_transaction::RpcTransaction;
+use starknet_api::test_utils::invoke::rpc_invoke_tx;
+use tracing_test::traced_test;
+
+use crate::config::ProverConfig;
+use crate::proving::virtual_snos_prover::RpcVirtualSnosProver;
+use crate::server::errors::ServiceErrorCode;
+use crate::server::rpc_api::ProvingRpcServer;
+use crate::server::rpc_impl::ProvingRpcServerImpl;
+
+/// Nothing listens here: every test below is rejected before the prover is called, so a request
+/// that slipped through fails loudly instead of quietly passing.
+const UNBOUND_RPC_NODE_URL: &str = "http://localhost:1";
+
+fn server(max_concurrent_requests: usize, max_queued_requests: usize) -> ProvingRpcServerImpl {
+    let config =
+        ProverConfig { rpc_node_url: UNBOUND_RPC_NODE_URL.to_string(), ..Default::default() };
+    ProvingRpcServerImpl::new(
+        RpcVirtualSnosProver::new(&config),
+        max_concurrent_requests,
+        max_queued_requests,
+        Duration::from_millis(1),
+    )
+}
+
+/// No admission permits at all, so a request is turned away without ever queueing.
+fn server_with_full_queue() -> ProvingRpcServerImpl {
+    server(0, 0)
+}
+
+/// One queue slot but no worker slots, so a request is admitted and then waits forever.
+fn server_with_no_free_worker() -> ProvingRpcServerImpl {
+    server(0, 1)
+}
+
+fn any_transaction() -> RpcTransaction {
+    rpc_invoke_tx(invoke_tx_args!())
+}
+
+/// With no admission permits the request is rejected outright, without waiting. Both rejection
+/// paths return the same code, so the log line is what distinguishes them - without it, deleting
+/// the admission check would leave this test passing via the queue-wait timeout instead.
+#[traced_test]
+#[tokio::test]
+async fn rejects_with_service_busy_when_the_queue_is_full() {
+    let server = server_with_full_queue();
+
+    let error = server
+        .prove_transaction(BlockId::Latest, any_transaction())
+        .await
+        .expect_err("a full queue must reject");
+
+    assert_eq!(error.code(), ServiceErrorCode::ServiceBusy.code());
+    assert!(logs_contain("queue is full"));
+    assert!(!logs_contain("timed out waiting for a worker slot"));
+}
+
+/// Admitted into the queue, but no worker slot ever frees up, so the queue-wait backstop fires.
+#[traced_test]
+#[tokio::test]
+async fn rejects_with_service_busy_when_waiting_for_a_worker_times_out() {
+    let server = server_with_no_free_worker();
+
+    let error = server
+        .prove_transaction(BlockId::Latest, any_transaction())
+        .await
+        .expect_err("an expired queue wait must reject");
+
+    assert_eq!(error.code(), ServiceErrorCode::ServiceBusy.code());
+    assert!(logs_contain("timed out waiting for a worker slot"));
+    assert!(!logs_contain("queue is full"));
+}
+
+/// `spec_version` must stay outside admission control: it is what a load balancer or the smoke
+/// script probes, and gating it behind proving capacity would make a busy service look down.
+#[tokio::test]
+async fn spec_version_is_served_even_when_the_queue_is_full() {
+    let server = server_with_full_queue();
+
+    server.spec_version().await.expect("spec_version must not be gated by proving capacity");
+}