initial commit for adding EMAS to adk-samples #286

heiko-hotz · 2025-07-29T15:18:01Z

Implements "Exploring Multi-Agent Systems" (EMAS) (fka Project Horizon) architecture

mstyer-google

I did a first pass through -- generally it looks great. I have some general standards-related comments that I added to the first .py file; those apply to all files in the PR.

I'll take another look through some of the more complex Python stuff tomorrow but I wanted to get this to you in the meantime.

mstyer-google · 2025-07-29T16:14:37Z

python/solutions/emas/.env.example

You have this file here and in the examples/stock_lookup_custom_a2a directory, but it probably doesn't need to be in both places.

mstyer-google · 2025-07-30T15:04:55Z

python/solutions/emas/examples/stock_lookup_custom_a2a/README.md

+        ```bash
+        cp .env.example .env
+        ```
+    *   Open the `.env` file and populate it with your specific configuration values (API keys, ports, etc.). Refer to the comments within `.env.example`.


I noticed your .env.example file has the VERTEX variables commented out. Is your recommendation that people should use the Google AI API instead?

mstyer-google · 2025-07-30T15:06:01Z

python/solutions/emas/examples/stock_lookup_custom_a2a/README.md

+4.  **Interact:**
+    *   Click "Connect".
+    *   Click the Mic button, speak a stock request (e.g., "What is the price of Apple?").
+    *   Click the Mic button again to stop recording.


It's a little confusing knowing whether to stop the recording or not. From experimenting it seems like you can just leave the recording running, but it would be useful to clarify how this is supposed to work.

mstyer-google · 2025-07-30T15:11:28Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

@@ -0,0 +1,361 @@
+# app/live_server.py


In general I think all the files need to have the Apache header, along with a file-level docstring.

mstyer-google · 2025-07-30T15:12:42Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/static/adk-websocket-api.js

+const EventEmitter = window.EventEmitter3;
+
+// --- Assume these classes are available globally or via imports ---
+// --- You MUST copy the corresponding .js files from Pastra   ---


Is this still true?

mstyer-google · 2025-07-30T15:15:44Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

@@ -0,0 +1,361 @@
+# app/live_server.py


Re formatting, we are trying to follow the Google OSS Python style guide. We used the black autoformatter to take care of most formatting issues, so if you could run that over this repo that would be a good start.

Line length is one issue I think will come up.

mstyer-google · 2025-07-30T15:17:23Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

@@ -0,0 +1,361 @@
+# app/live_server.py


The Python style guide also asks for our Python code to be pylint-clean, either by fixing the issues or disabling inappropriate / inapplicable warnings using #pylint: disable=...

mstyer-google · 2025-07-30T15:28:02Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

@@ -0,0 +1,361 @@
+# app/live_server.py


Other docstrings are also important - class- and function-level.

mstyer-google · 2025-07-30T15:32:49Z

python/solutions/emas/examples/stock_lookup_custom_a2a/host_agent/agent.py

+
+# --- Dynamic Instruction Builder ---
+def get_host_agent_instruction() -> str:
+    base_instruction = (


""" quotes would likely be easier to read here.

mstyer-google · 2025-07-30T15:40:51Z

...ons/emas/examples/stock_lookup_custom_a2a/specialist_agents/stock_info_agent/task_manager.py

+                 logger.debug(f"A2A Task Mgr (ADK Mode): ADK Event: {event.author} - Final: {event.is_final_response()}")
+                 # We need to extract the *tool result* that the agent processed
+                 # The final response *from the ADK agent* isn't directly what the A2A server should return.
+                 if event.get_function_responses():


This conditional is a bit hard to follow, just from the indenting if nothing else. Could you break or continue on negative conditions instead of nesting the conditions?

E.g.

if not event.get_function_response(): continue for func_resp in event.get_function_responses(): if func_resp.name != "get_current_stock_price": continue

etc.

mstyer-google

OK, I've done a deeper pass over the Python code. A few things here to look at.

mstyer-google · 2025-08-01T09:49:57Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

+        )
+        logger.info(f"ADK run_live started for session {session_id}")
+
+        async def adk_to_client():


Can you move these definitions (this one and the one below) out of the try ... except block, and just call them in the block instead?? That would make the logic of this function clearer, and would also let you have longer lines without running into line length constraints.

mstyer-google · 2025-08-01T09:53:01Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

+            nonlocal adk_session
+            logger.debug(f"[{session_id}] ADK -> Client task started.")
+            audio_chunk_counter = 0
+            try:


If you're handling exceptions in the outer block, why do you need a try ... except block in these functions?

mstyer-google · 2025-08-01T09:55:51Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

+                        if not is_tool_event:
+                             logger.debug(f"[{session_id}] Skipping event: Author={event.author}, Partial={event.partial}, Content Type={type(event.content.parts[0]).__name__ if event.content and event.content.parts else 'None'}")
+                        else:
+                             if event.get_function_calls():


Can you just add these as elif statements on the containing block?

mstyer-google · 2025-08-01T09:56:17Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

+        async def client_to_adk():
+            nonlocal adk_session
+            logger.debug(f"[{session_id}] Client -> ADK task started.")
+            try:


Same comment as above about try ... except at this level.

mstyer-google · 2025-08-01T10:06:15Z

python/solutions/emas/examples/stock_lookup_custom_a2a/app/live_server.py

+    app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")
+    logger.info(f"Serving static files from {STATIC_DIR}")
+
+    @app.get("/")


Isn't there a way to configure a default for "GET /" that returns "/index.html", so you don't need to handle that in code? I'm sure e.g. Apache does this out of the box.

mstyer-google · 2025-08-01T11:13:11Z

python/solutions/emas/examples/stock_lookup_custom_a2a/host_agent/agent.py

+load_dotenv(dotenv_path=dotenv_path, override=True)
+
+# Import the new tool and discovery cache
+try:


Do you need to make this import conditional? when do you expect this import to fail?

mstyer-google · 2025-08-01T11:17:20Z

python/solutions/emas/examples/stock_lookup_custom_a2a/host_agent/agent.py

+    return base_instruction
+
+# --- Agent Definition ---
+host_agent: Optional[Agent] = None


Why is this a global?

mstyer-google · 2025-08-01T11:29:38Z

.../solutions/emas/examples/stock_lookup_custom_a2a/specialist_agents/stock_info_agent/agent.py

+        name="stock_info_agent",
+        model=MODEL,
+        description="Provides current stock price information using an external tool.",
+        instruction="You are an assistant that provides stock prices. "


""" quotes might be more readable here.

mstyer-google · 2025-08-01T11:33:56Z

python/solutions/emas/examples/stock_lookup_custom_a2a/common_impl/utils/in_memory_cache.py

+from typing import Any, Dict, Optional
+
+
+class InMemoryCache:


Where is this used? I can't find it anywhere?

mstyer-google · 2025-08-01T11:35:28Z

.../solutions/emas/examples/stock_lookup_custom_a2a/common_impl/utils/push_notification_auth.py

+        )
+        return hashlib.sha256(body_str.encode()).hexdigest()
+
+class PushNotificationSenderAuth(PushNotificationAuth):


Also can't find this -- where are these classes used?

initial commit for adding EMAS to adk-samples

1a37e22

mstyer-google self-assigned this Jul 29, 2025

mstyer-google reviewed Jul 30, 2025

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mstyer-google requested changes Aug 1, 2025

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Merge branch 'main' into feat/emas

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initial commit for adding EMAS to adk-samples #286

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initial commit for adding EMAS to adk-samples #286

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heiko-hotz commented Jul 29, 2025

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