# Session Isolation

> Key all session state and memory by user identity end-to-end — so one user's agent can never read, write, or be influenced by another user's data.

- **Category**: Agentic AI
- **Subcategory**: Memory
- **Canonical URL**: https://designpattern.fyi/patterns/session_isolation/

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## Description
**Intent**: Keep one user's session state and memory unreachable from another user's agent.
**Context**: You're shipping an agent product to many users. Each expects their conversation history, preferences, and shared data to stay private. For cost and operational reasons, the backend shares infrastructure across users — caches, vector stores, model contexts — rather than running a fully isolated stack per user.
**Solution**: Session state is keyed by per-user identity (OAuth/JWT subject). Reads and writes carry that identity end-to-end. Caches are scoped per user. Prompts never include another user's content.



## Use Cases
- Multiple users share an agent backend and cross-user data leaks are unacceptable.
- Session state and caches can be keyed end-to-end by user identity.
- Auth identity (OAuth, JWT subject) flows through the full stack.






## Trade-offs


### Advantages

- Privacy and security boundary is explicit, testable, and structurally enforced.

- Multi-tenant compliance posture is simpler — the isolation is the policy.




### Considerations & Drawbacks

- Loss of cross-user cache benefits — shared embeddings, shared precomputed results.

- Auth identity must be plumbed through every layer — easy to miss one.







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**Reference**: [Original Source](https://www.agentpatternscatalog.org/patterns/session-isolation/)