Missing type stub for agent_engines.memories.retrieve() method

[UdayRajVadeghar]

Missing Type Stubs for client.agent_engines.memories.retrieve() in Google ADK

Description

The client.agent_engines.memories.retrieve() method works correctly at runtime, but it is missing from the type stubs. As a result, IDEs and type checkers (Pylance, Pyright, mypy) report errors such as:

Cannot access attribute "retrieve" for class "_AgentEngineMemories"

The method itself does exist and functions properly during execution.

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Environment

• google-adk version: (run: pip show google-adk)
• vertexai version: (run: pip show google-cloud-aiplatform)
• Python version: 3.12

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Steps to Reproduce

import vertexai

client = vertexai.Client(project="my-project", location="us-central1")

# Works at runtime, but IDE reports a type error
retrieved_memories = client.agent_engines.memories.retrieve(
    name="projects/.../reasoningEngines/...",
    scope={"app_name": "test", "user_id": "user123"},
    similarity_search_params={"search_query": "*"}
)

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Expected Behavior

The SDK's type stubs should correctly declare the retrieve() method so that IDEs and type checkers do not show false errors.

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Actual Behavior

• Runtime: works correctly, method is available and returns results.

• Type checking: fails with errors such as:

  • Cannot access attribute "retrieve" for class "_AgentEngineMemories"

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Additional Context

• The implementation exists in vertexai/_genai/memories.py (around lines 1182–1233, inside the Memories class).
• However, the type stub files (.pyi) do not expose this method.
• Other methods under agent_engines.memories such as generate(), create(), list(), and get() may also require type stub validation.

This issue affects static analysis and IDE tooling but not runtime functionality. A stub update should resolve it.