diff --git a/packages/core/aqua-to-js/src/generate/__test__/generate.spec.ts b/packages/core/aqua-to-js/src/generate/__test__/generate.spec.ts
index 1deadbe8..5de31ffe 100644
--- a/packages/core/aqua-to-js/src/generate/__test__/generate.spec.ts
+++ b/packages/core/aqua-to-js/src/generate/__test__/generate.spec.ts
@@ -45,7 +45,7 @@ describe("Aqua to js/ts compiler", () => {
     };
   });
 
-  it("matches js snapshot", async () => {
+  it("matches js snapshots", async () => {
     const jsResult = generateSources(res, "js", pkg);
     const jsTypes = generateTypes(res, pkg);
 
@@ -58,7 +58,7 @@ describe("Aqua to js/ts compiler", () => {
     );
   });
 
-  it("matches ts snapshot", async () => {
+  it("matches ts snapshots", async () => {
     const tsResult = generateSources(res, "ts", pkg);
 
     await expect(tsResult).toMatchFileSnapshot(
diff --git a/packages/core/aqua-to-js/src/generate/header.ts b/packages/core/aqua-to-js/src/generate/header.ts
index ce4cfc17..17ce9763 100644
--- a/packages/core/aqua-to-js/src/generate/header.ts
+++ b/packages/core/aqua-to-js/src/generate/header.ts
@@ -39,6 +39,7 @@ ${
     : ""
 }
 
+// Making aliases to reduce chance of accidental name collision
 import {
     v5_callFunction as callFunction$$,
     v5_registerService as registerService$$,
diff --git a/packages/core/aqua-to-js/src/generate/interfaces.ts b/packages/core/aqua-to-js/src/generate/interfaces.ts
index ef330d10..3a8c400a 100644
--- a/packages/core/aqua-to-js/src/generate/interfaces.ts
+++ b/packages/core/aqua-to-js/src/generate/interfaces.ts
@@ -119,19 +119,24 @@ export class TSTypeGenerator implements TypeGenerator {
     const serviceDecl = `service: ${srvName}Def`;
     const serviceIdDecl = `serviceId: string`;
 
+    const functionOverloadsWithDefaultServiceId = [
+      [serviceDecl],
+      [serviceIdDecl, serviceDecl],
+      [peerDecl, serviceDecl],
+      [peerDecl, serviceIdDecl, serviceDecl],
+    ];
+
+    const functionOverloadsWithoutDefaultServiceId = [
+      [serviceIdDecl, serviceDecl],
+      [peerDecl, serviceIdDecl, serviceDecl],
+    ];
+
     const registerServiceArgs =
+      // This wrong type comes from aqua team. We need to discuss fix with them
       // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
       (srvDef.defaultServiceId as DefaultServiceId).s_Some__f_value != null
-        ? [
-            [serviceDecl],
-            [serviceIdDecl, serviceDecl],
-            [peerDecl, serviceDecl],
-            [peerDecl, serviceIdDecl, serviceDecl],
-          ]
-        : [
-            [serviceIdDecl, serviceDecl],
-            [peerDecl, serviceIdDecl, serviceDecl],
-          ];
+        ? functionOverloadsWithDefaultServiceId
+        : functionOverloadsWithoutDefaultServiceId;
 
     return [
       interfaces,
diff --git a/packages/core/aqua-to-js/src/generate/service.ts b/packages/core/aqua-to-js/src/generate/service.ts
index c06963a0..c58d3fd1 100644
--- a/packages/core/aqua-to-js/src/generate/service.ts
+++ b/packages/core/aqua-to-js/src/generate/service.ts
@@ -20,6 +20,7 @@ import { recursiveRenameLaquaProps } from "../utils.js";
 
 import { TypeGenerator } from "./interfaces.js";
 
+// Actual value of defaultServiceId which comes from aqua-api
 export interface DefaultServiceId {
   s_Some__f_value?: string;
 }
diff --git a/packages/core/aqua-to-js/src/generate/validators.ts b/packages/core/aqua-to-js/src/generate/validators.ts
index 78c3d6d2..5e917a98 100644
--- a/packages/core/aqua-to-js/src/generate/validators.ts
+++ b/packages/core/aqua-to-js/src/generate/validators.ts
@@ -18,12 +18,39 @@ import {
   ArrowWithoutCallbacks,
   FunctionCallDef,
   JSONValue,
+  ScalarType,
   SimpleTypes,
   UnlabeledProductType,
 } from "@fluencelabs/interfaces";
 
 import { typeToTs } from "../common.js";
 
+const numberTypes = [
+  "u8",
+  "u16",
+  "u32",
+  "u64",
+  "i8",
+  "i16",
+  "i32",
+  "i64",
+  "f32",
+  "f64",
+];
+
+function isScalar(schema: ScalarType, arg: JSONValue) {
+  if (numberTypes.includes(schema.name)) {
+    return typeof arg === "number";
+  } else if (schema.name === "bool") {
+    return typeof arg === "boolean";
+  } else if (schema.name === "string") {
+    return typeof arg === "string";
+  } else {
+    // Should not be possible
+    return false;
+  }
+}
+
 export function validateFunctionCall(
   schema: FunctionCallDef,
   ...args: JSONValue[]
@@ -47,12 +74,12 @@ export function validateFunctionCall(
 export function validateFunctionCallArg(
   schema: SimpleTypes | UnlabeledProductType | ArrowWithoutCallbacks,
   arg: JSONValue,
-  argIndex: number,
+  argPosition: number,
 ) {
   if (!isTypeMatchesSchema(schema, arg)) {
     const expectedType = typeToTs(schema);
     throw new Error(
-      `Argument ${argIndex} doesn't match schema. Expected type: ${expectedType}`,
+      `Argument ${argPosition} doesn't match schema. Expected type: ${expectedType}`,
     );
   }
 }
@@ -66,29 +93,7 @@ export function isTypeMatchesSchema(
   } else if (schema.tag === "option") {
     return arg === null || isTypeMatchesSchema(schema.type, arg);
   } else if (schema.tag === "scalar") {
-    if (
-      [
-        "u8",
-        "u16",
-        "u32",
-        "u64",
-        "i8",
-        "i16",
-        "i32",
-        "i64",
-        "f32",
-        "f64",
-      ].includes(schema.name)
-    ) {
-      return typeof arg === "number";
-    } else if (schema.name === "bool") {
-      return typeof arg === "boolean";
-    } else if (schema.name === "string") {
-      return typeof arg === "string";
-    } else {
-      // Should not be possible
-      return false;
-    }
+    return isScalar(schema, arg);
   } else if (schema.tag === "array") {
     return (
       Array.isArray(arg) &&
diff --git a/packages/core/aqua-to-js/src/utils.ts b/packages/core/aqua-to-js/src/utils.ts
index 7527f7c2..6ab0b53f 100644
--- a/packages/core/aqua-to-js/src/utils.ts
+++ b/packages/core/aqua-to-js/src/utils.ts
@@ -33,6 +33,7 @@ const packageJsonSchema = z.object({
   name: z.string(),
   version: z.string(),
   devDependencies: z.object({
+    // This version used in header file
     ["@fluencelabs/aqua-api"]: z.string(),
   }),
 });
diff --git a/packages/core/js-client/src/api.ts b/packages/core/js-client/src/api.ts
index 77702849..2544b522 100644
--- a/packages/core/js-client/src/api.ts
+++ b/packages/core/js-client/src/api.ts
@@ -33,6 +33,17 @@ import { FluencePeer } from "./jsPeer/FluencePeer.js";
 
 import { callAquaFunction, Fluence, registerService } from "./index.js";
 
+const isAquaConfig = (
+  config: JSONValue | ServiceImpl[string] | undefined,
+): config is CallAquaFunctionConfig => {
+  return (
+    typeof config === "object" &&
+    config !== null &&
+    !Array.isArray(config) &&
+    ["undefined", "number"].includes(typeof config["ttl"])
+  );
+};
+
 /**
  * Convenience function to support Aqua `func` generation backend
  * The compiler only need to generate a call the function and provide the corresponding definitions and the air script
@@ -47,9 +58,11 @@ export const v5_callFunction = async (
   script: string,
 ): Promise<unknown> => {
   const argNames = Object.keys(def.arrow);
-  const argCount = argNames.length;
+  const schemaArgCount = argNames.length;
 
-  const functionArgs: Record<string, SimpleTypes | ArrowWithoutCallbacks> =
+  type FunctionArg = SimpleTypes | ArrowWithoutCallbacks;
+
+  const schemaFunctionArgs: Record<string, FunctionArg> =
     def.arrow.domain.tag === "nil" ? {} : def.arrow.domain.fields;
 
   let peer: FluencePeer | undefined;
@@ -61,26 +74,26 @@ export const v5_callFunction = async (
     peer = Fluence.defaultClient;
   }
 
-  // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
-  const config =
-    argCount < args.length
-      ? // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
-        (args.pop() as CallAquaFunctionConfig | undefined)
-      : undefined;
-
   if (peer == null) {
     throw new Error(
       "Could not register Aqua service because the client is not initialized. Did you forget to call Fluence.connect()?",
     );
   }
 
+  // if args more than expected in schema (schemaArgCount) then last arg is config
+  const config = schemaArgCount < args.length ? args.pop() : undefined;
+
+  if (!isAquaConfig(config)) {
+    throw new Error("Config should be object type");
+  }
+
   const callArgs = Object.fromEntries<JSONValue | ServiceImpl[string]>(
-    args.slice(0, argCount).map((arg, i) => {
-      const argSchema = functionArgs[argNames[i]];
+    args.slice(0, schemaArgCount).map((arg, i) => {
+      const argSchema = schemaFunctionArgs[argNames[i]];
 
       if (argSchema.tag === "arrow") {
         if (typeof arg !== "function") {
-          throw new Error("Argument and schema doesn't match");
+          throw new Error("Argument and schema don't match");
         }
 
         const wrappedFunction = wrapFunction(arg, argSchema);
@@ -89,7 +102,7 @@ export const v5_callFunction = async (
       }
 
       if (typeof arg === "function") {
-        throw new Error("Argument and schema doesn't match");
+        throw new Error("Argument and schema don't match");
       }
 
       return [argNames[i], ts2aqua(arg, argSchema)];
@@ -111,13 +124,13 @@ export const v5_callFunction = async (
     fireAndForget: returnTypeVoid,
   });
 
-  const valueSchema =
+  const returnSchema =
     def.arrow.codomain.tag === "unlabeledProduct" &&
     def.arrow.codomain.items.length === 1
       ? def.arrow.codomain.items[0]
       : def.arrow.codomain;
 
-  return aqua2ts(result, valueSchema);
+  return aqua2ts(result, returnSchema);
 };
 
 /**
@@ -145,7 +158,13 @@ export const v5_registerService = (args: unknown[], def: ServiceDef): void => {
     );
   }
 
-  if (typeof args[0] === "string") {
+  if (args.length === 2) {
+    if (typeof args[0] !== "string") {
+      throw new Error(
+        `Service ID should be of type string. ${typeof args[0]} provided.`,
+      );
+    }
+
     serviceId = args[0];
   }
 
@@ -153,8 +172,10 @@ export const v5_registerService = (args: unknown[], def: ServiceDef): void => {
     throw new Error("Service ID is not provided");
   }
 
+  // Schema for every function in service
   const serviceSchema = def.functions.tag === "nil" ? {} : def.functions.fields;
 
+  // Wrapping service impl to convert their args ts -> aqua and backwards
   const wrappedServiceImpl = Object.fromEntries(
     Object.entries(serviceImpl).map(([name, func]) => {
       return [name, wrapFunction(func, serviceSchema[name])];
diff --git a/packages/core/js-client/src/clientPeer/__test__/client.spec.ts b/packages/core/js-client/src/clientPeer/__test__/client.spec.ts
index fc347a83..dc6c548b 100644
--- a/packages/core/js-client/src/clientPeer/__test__/client.spec.ts
+++ b/packages/core/js-client/src/clientPeer/__test__/client.spec.ts
@@ -25,8 +25,10 @@ import { checkConnection } from "../checkConnection.js";
 
 import { nodes, RELAY } from "./connection.js";
 
+const ONE_SECOND = 1000;
+
 describe("FluenceClient usage test suite", () => {
-  it("Should resolve at TTL when fire and forget behavior is used", async () => {
+  it("Should stop particle processing after TTL is reached", async () => {
     await withClient(RELAY, { defaultTtlMs: 600 }, async (peer) => {
       const script = `
     (seq
@@ -36,7 +38,7 @@ describe("FluenceClient usage test suite", () => {
 
       const particle = await peer.internals.createNewParticle(script);
 
-      const now = Date.now();
+      const start = Date.now();
 
       const promise = new Promise<JSONValue>((resolve, reject) => {
         registerHandlersHelper(peer, particle, {
@@ -51,7 +53,11 @@ describe("FluenceClient usage test suite", () => {
       });
 
       await expect(promise).rejects.toThrow(ExpirationError);
-      expect(Date.now() - 500).toBeGreaterThanOrEqual(now);
+
+      expect(
+        Date.now() - 500,
+        "Particle processing didn't stop after TTL is reached",
+      ).toBeGreaterThanOrEqual(start);
     });
   });
 
@@ -209,13 +215,17 @@ describe("FluenceClient usage test suite", () => {
       );
     });
 
-    it("With connection options: defaultTTL", async () => {
-      await withClient(RELAY, { defaultTtlMs: 1 }, async (peer) => {
-        const isConnected = await checkConnection(peer);
+    it(
+      "With connection options: defaultTTL",
+      async () => {
+        await withClient(RELAY, { defaultTtlMs: 1 }, async (peer) => {
+          const isConnected = await checkConnection(peer);
 
-        expect(isConnected).toBeFalsy();
-      });
-    }, 1000);
+          expect(isConnected).toBeFalsy();
+        });
+      },
+      ONE_SECOND,
+    );
   });
 
   it.skip("Should throw correct error when the client tries to send a particle not to the relay", async () => {
@@ -247,15 +257,11 @@ describe("FluenceClient usage test suite", () => {
           particle,
           () => {},
           (error: Error) => {
-            if (error instanceof SendError) {
-              reject(error.message);
-            }
+            reject(error);
           },
         );
       });
 
-      await promise;
-
       await expect(promise).rejects.toMatch(
         "Particle is expected to be sent to only the single peer (relay which client is connected to)",
       );
diff --git a/packages/core/js-client/src/compilerSupport/callFunction.ts b/packages/core/js-client/src/compilerSupport/callFunction.ts
index a062b326..7042fea8 100644
--- a/packages/core/js-client/src/compilerSupport/callFunction.ts
+++ b/packages/core/js-client/src/compilerSupport/callFunction.ts
@@ -69,6 +69,7 @@ export const callAquaFunction = async ({
   const particle = await peer.internals.createNewParticle(script, config.ttl);
 
   return new Promise<JSONValue>((resolve, reject) => {
+    // Registering function args as a services
     for (const [name, argVal] of Object.entries(args)) {
       let service: ServiceDescription;
 
diff --git a/packages/core/js-client/src/compilerSupport/conversions.ts b/packages/core/js-client/src/compilerSupport/conversions.ts
index cfb6cf5c..63c44783 100644
--- a/packages/core/js-client/src/compilerSupport/conversions.ts
+++ b/packages/core/js-client/src/compilerSupport/conversions.ts
@@ -147,12 +147,12 @@ export const wrapFunction = (
 
     const result = await value(...tsArgs, context);
 
-    const valueSchema =
+    const resultSchema =
       schema.codomain.tag === "unlabeledProduct" &&
       schema.codomain.items.length === 1
         ? schema.codomain.items[0]
         : schema.codomain;
 
-    return ts2aqua(result, valueSchema);
+    return ts2aqua(result, resultSchema);
   };
 };
diff --git a/packages/core/js-client/src/ephemeral/client.ts b/packages/core/js-client/src/ephemeral/client.ts
index c4d45773..e95e0bdf 100644
--- a/packages/core/js-client/src/ephemeral/client.ts
+++ b/packages/core/js-client/src/ephemeral/client.ts
@@ -37,6 +37,7 @@ export class EphemeralNetworkClient extends FluencePeer {
   ) {
     const workerLoader = new WorkerLoader();
 
+    // TODO: use js-client-isomorphic
     const controlModuleLoader = new WasmLoaderFromNpm(
       "@fluencelabs/marine-js",
       "marine-js.wasm",
diff --git a/packages/core/js-client/src/ephemeral/network.ts b/packages/core/js-client/src/ephemeral/network.ts
index ba8cf710..88514ed5 100644
--- a/packages/core/js-client/src/ephemeral/network.ts
+++ b/packages/core/js-client/src/ephemeral/network.ts
@@ -232,6 +232,7 @@ export class EphemeralNetwork {
     // shared worker for all the peers
     this.workerLoader = new WorkerLoaderFromFs("../../marine/worker-script");
 
+    // TODO: use js-client-isomorphic
     this.controlModuleLoader = new WasmLoaderFromNpm(
       "@fluencelabs/marine-js",
       "marine-js.wasm",
diff --git a/packages/core/js-client/src/jsPeer/FluencePeer.ts b/packages/core/js-client/src/jsPeer/FluencePeer.ts
index c14a6a46..3764e7bd 100644
--- a/packages/core/js-client/src/jsPeer/FluencePeer.ts
+++ b/packages/core/js-client/src/jsPeer/FluencePeer.ts
@@ -538,6 +538,17 @@ export abstract class FluencePeer {
                       "id %s. send successful",
                       newParticle.id,
                     );
+
+                    if (
+                      this.jsServiceHost.getHandler(
+                        "callbackSrv",
+                        "response",
+                        item.particle.id,
+                      ) == null
+                    ) {
+                      // try to finish script if fire-and-forget enabled
+                      item.onSuccess({});
+                    }
                   })
                   .catch((e: unknown) => {
                     log_particle.error(
@@ -623,10 +634,9 @@ export abstract class FluencePeer {
                     "callbackSrv",
                     "response",
                     item.particle.id,
-                  ) == null &&
-                  item.result.nextPeerPks.length === 0
+                  ) == null
                 ) {
-                  // try to finish script
+                  // try to finish script if fire-and-forget enabled
                   item.onSuccess({});
                 }
               }
diff --git a/packages/core/js-client/src/util/testUtils.ts b/packages/core/js-client/src/util/testUtils.ts
index da7967ff..5ce57f11 100644
--- a/packages/core/js-client/src/util/testUtils.ts
+++ b/packages/core/js-client/src/util/testUtils.ts
@@ -148,6 +148,7 @@ export class TestPeer extends FluencePeer {
   constructor(keyPair: KeyPair, connection: IConnection) {
     const workerLoader = new WorkerLoader();
 
+    // TODO: use js-client-isomorphic
     const controlModuleLoader = new WasmLoaderFromNpm(
       "@fluencelabs/marine-js",
       "marine-js.wasm",
@@ -193,6 +194,7 @@ export const withClient = async (
 ) => {
   const workerLoader = new WorkerLoader();
 
+  // TODO: use js-client-isomorphic
   const controlModuleLoader = new WasmLoaderFromNpm(
     "@fluencelabs/marine-js",
     "marine-js.wasm",