feat(ethexe/rpc): Add streaming subscription for all ethexe promises to RPC

ethexe/rpc/client/src/apis/injected/mod.rs

@@ -1,6 +1,7 @@
 // Copyright (C) Gear Technologies Inc.
 // SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
 
+use crate::types::PromiseSubscriptionFilter;
 use ethexe_common::{
     HashOf,
     injected::{
@@ -30,6 +31,19 @@ pub trait Injected {
         transaction: SignedInjectedTransaction,
     ) -> jsonrpsee::core::SubscriptionResult;
 
+    /// Subscribes to a stream of all newly computed promises. Promises are
+    /// delivered as they are computed; there is no replay of historical
+    /// promises. An optional filter narrows the stream per subscriber.
+    #[subscription(
+        name = "subscribePromises",
+        unsubscribe = "unsubscribePromises",
+        item = crate::types::PromiseEnvelope
+    )]
+    async fn subscribe_promises(
+        &self,
+        filter: Option<PromiseSubscriptionFilter>,
+    ) -> jsonrpsee::core::SubscriptionResult;
+
     #[method(name = "getTransactionReceipt")]
     async fn get_transaction_receipt(
         &self,

ethexe/rpc/common/Cargo.toml

@@ -20,5 +20,8 @@ gprimitives = { workspace = true, features = ["serde", "ethexe"] }
 serde = { workspace = true, features = ["std"] }
 gear-workspace-hack.workspace = true
 
+[dev-dependencies]
+serde_json.workspace = true
+
 [lints]
 workspace = true