> For the complete documentation index, see [llms.txt](https://docs.northstar.sonicsvm.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.northstar.sonicsvm.org/architecture.md).

# Architecture

How NorthStar executes, confirms, and settles session state.

NorthStar splits execution between Solana L1 and an Ephemeral Rollup. This section covers the system behavior that makes sessions fast, isolated, and safe to settle back.

## In this section

* [ER Topology](/architecture/er-topology.md) — components and the data flow for a full session lifecycle.
* [Real-Time Confirmation](/architecture/real-time.md) — how confirmation reaches millisecond-scale latency.
* [Security Model](/architecture/security.md) — trust assumptions, custody guarantees, and the challenge protocol.

## Architectural focus

Use this section to understand:

* where execution happens
* when a transaction is considered confirmed
* how ER state becomes canonical on L1
* what holds when an operator misbehaves

For the user-facing model, start with [Concepts](/concepts.md). For protocol details, use [Reference](/reference.md).


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