Add memory to a Python agent

The client reads the key from the argument or from the environment. Prefer the environment: a key in source is a key in your git history.

pip install persistmemory
export PERSISTMEMORY_API_KEY="pm_..."

Query for what earlier runs established and put it in the prompt. Recall returns a handful of memories rather than the whole history, so this stays the same size whether the agent has run twice or two thousand times.

from persistmemory import PersistMemory

client = PersistMemory()

def recall(topic: str, limit: int = 5) -> str:
    found = client.search.query(query=topic, limit=limit)
    if not found.results:
        return "Nothing known about this yet."
    return "\n".join(f"- {r.memory.content}" for r in found.results)

Write the conclusion, not the transcript. A memory is something that will still be true and still be useful next month; the reasoning that produced it usually is not.

def establish(finding: str) -> None:
    # Returns a job. Extraction runs afterwards and may produce one
    # memory, several, or none, so do not treat this as a write that
    # you can immediately read back.
    client.memories.remember(text=finding)

Writing every intermediate thought is the common mistake. It fills recall with the agent's own noise, and next month's run is then reasoning about last month's reasoning rather than about what was true.

Two calls, one before and one after. That is the whole integration.

def run(task: str) -> str:
    context = recall(task)

    answer = your_agent(
        task,
        system=f"What you already know:\n{context}"
    )

    if answer.confident:
        establish(answer.finding)

    return answer.text

If one agent serves several customers, pass a space so recall cannot cross between them. Access rules attached to a source are carried through and never widened, and a space is how you say which world a memory belongs to.

client.search.query(query=task, space_ids=["spc_northwind"], limit=5)
client.memories.remember(text=finding, space_ids=["spc_northwind"])

Worth doing from the first day rather than retrofitting. Memories written without a space are not automatically placed in one later, so a multi-tenant agent that skipped this has a mixing problem to clean up rather than a setting to change.