> For the complete documentation index, see [llms.txt](https://docs.convai.com/api-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.convai.com/api-docs/plugins-and-integrations/convai-unity-sdk/core-concepts.md). # Core concepts The Core Concepts section explains the systems that run beneath every Convai character in your scene — the runtime layers that manage connections, the session state machine that governs each character's lifecycle, the turn-taking system that controls who speaks and when, and the event components that let your scene react to what happens at runtime. Start with **Runtime architecture** if you are new to the SDK internals. Read the other pages when you need to configure a specific system or understand why the SDK behaves a certain way.
Runtime architecture
Runtime layers, interface inventory, and what you can replace.		/pages/LV9IsLoeHhBA2EovBKod
Session lifecycle
State machine, per-character sessions, persistence, and reconnection.		/pages/TvL9WjMsqfa9XQdTFSUo
Turn-taking modes
Hands-free vs. push-to-talk — every field and policy explained.		/pages/b9e67d1d27aaccf9e9bc9b260045411047aa37c3
Event system
Relay components, payload types, and subscription patterns.		/pages/bcd284a409f00820e1693ab998dc7a99a4fbd780
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