feat(gateway): Requirement to stop L1->L2 transactions before v26 upgrade (#3707)

## What ❔

A way to disable the addition of new L1->L2 transactions completely
before the start of the upgrade.

The chains will be expected to firstly set the new config value to
`true` (and wait until all the older txs are processed) and after the
end of the upgrade return it back to `false` (or remove completely)

## Why ❔

<!-- Why are these changes done? What goal do they contribute to? What
are the principles behind them? -->
<!-- The `Why` has to be clear to non-Matter Labs entities running their
own ZK Chain -->
<!-- Example: PR templates ensure PR reviewers, observers, and future
iterators are in context about the evolution of repos. -->

## Is this a breaking change?

This is a breaking change for zkstack_cli functionality for gateway
upgrade as new server version would be required for it to work.

- [x] Yes
- [ ] No

## Operational changes
<!-- Any config changes? Any new flags? Any changes to any scripts? -->
<!-- Please add anything that non-Matter Labs entities running their own
ZK Chain may need to know -->

## Checklist

<!-- Check your PR fulfills the following items. -->
<!-- For draft PRs check the boxes as you complete them. -->

- [x] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [ ] Tests for the changes have been added / updated.
- [ ] Documentation comments have been added / updated.
- [x] Code has been formatted via `zkstack dev fmt` and `zkstack dev
lint`.

Author: StanislavBreadless

zkstack_cli/crates/zkstack/src/commands/dev/commands/events_gatherer.rs

@@ -144,13 +144,15 @@ pub(crate) async fn get_logs_for_events(
             // Sleep for 1 second before each JSON-RPC request to avoid hitting rate limits
             sleep(Duration::from_secs(1)).await;
 
-            let logs = match provider.get_logs(&filter).await {
-                Ok(ls) => ls,
-                Err(e) => {
-                    eprintln!(
-                        "Failed to fetch logs for event signature {event_sig} at {contract_address:?}: {e}"
-                    );
-                    continue;
+            let logs = loop {
+                match provider.get_logs(&filter).await {
+                    Ok(ls) => break ls,
+                    Err(e) => {
+                        eprintln!(
+                            "Failed to fetch logs for event signature {event_sig} at {contract_address:?}: {e}"
+                        );
+                        continue;
+                    }
                 }
             };
 

zkstack_cli/crates/zkstack/src/commands/dev/commands/gateway.rs

@@ -926,6 +926,37 @@ pub fn get_admin_call_builder(
     admin_calls_finalize
 }
 
+async fn check_no_l1_txs_absence(l2_rpc_url: &str, l2_chain_id: u64) -> anyhow::Result<()> {
+    let client = get_zk_client(l2_rpc_url, l2_chain_id)?;
+
+    let status = match client.l1_to_l2_txs_status().await {
+        Ok(x) => x,
+        Err(e) => {
+            anyhow::bail!("Failed to query the status for L1->L2 transactions. The error {:#?}. Please ensure that you run the correct server version and `unstable` namespace is enabled.", e)
+        }
+    };
+
+    anyhow::ensure!(
+        status.l1_to_l2_txs_paused,
+        "L1->L2 transactions have not been paused"
+    );
+    anyhow::ensure!(
+        status.l1_to_l2_txs_in_mempool == 0,
+        "There are still L1->L2 transactions present in the mempool"
+    );
+
+    Ok(())
+}
+
+fn print_error(err: anyhow::Error) {
+    println!(
+        "Chain is not ready to finalize the upgrade due to the reason:\n{:#?}",
+        err
+    );
+    println!("Once the chain is ready, you can re-run this command to obtain the calls to finalize the upgrade");
+    println!("If you want to display finalization params anyway, pass `--force-display-finalization-params=true`.");
+}
+
 pub(crate) async fn run(shell: &Shell, args: GatewayUpgradeCalldataArgs) -> anyhow::Result<()> {
     // 0. Read the GatewayUpgradeInfo
 
@@ -939,6 +970,15 @@ pub(crate) async fn run(shell: &Shell, args: GatewayUpgradeCalldataArgs) -> anyh
 
     // 2. Generate calldata
 
+    if !args.force_display_finalization_params.unwrap_or_default() {
+        println!("Checking whether L1->L2 transactions are disabled...");
+        if let Err(e) = check_no_l1_txs_absence(&args.l2_rpc_url, args.chain_id).await {
+            print_error(e);
+            return Ok(());
+        }
+        println!("All the L1->L2 have been paused. We can safely proceed with v26 upgrade.");
+    }
+
     let schedule_calldata = set_upgrade_timestamp_calldata(
         upgrade_info.new_protocol_version,
         args.server_upgrade_timestamp,
@@ -963,12 +1003,7 @@ pub(crate) async fn run(shell: &Shell, args: GatewayUpgradeCalldataArgs) -> anyh
         .await;
 
         if let Err(err) = chain_readiness {
-            println!(
-                "Chain is not ready to finalize the upgrade due to the reason:\n{:#?}",
-                err
-            );
-            println!("Once the chain is ready, you can re-run this command to obtain the calls to finalize the upgrade");
-            println!("If you want to display finalization params anyway, pass `--force-display-finalization-params=true`.");
+            print_error(err);
             return Ok(());
         };
     }