Synthetic Heart: Persistent AI Persona Memory Across Chats

Tired of your AI character forgetting who it is the moment you open a new chat? Synthetic Heart is built to stop that reset — a modular app and framework for builders who want one persona to stay the same person across every chat interface. The trick is that its state lives in a database instead of the chat window, so memory, a diary, self-knowledge and emotion state all survive after the conversation ends.

What Synthetic Heart Is

Synthetic Heart, shortened to SyntH, is a modular application and framework for builders creating persistent AI personas. Its core idea is persistent, database-backed state: memory, a diary, self-knowledge and an emotion state that stay put over time instead of resetting with each session.

The feature list covers a lot of ground:

• Multi-interface presence. The built-in WebUI, Discord, Telegram and Matrix all connect to the same persona, and messages stay in one chain.
• Switchable engines. Gemini, OpenAI, Claude, Grok or a local OpenAI-compatible instance can be hot-swapped at runtime.
• Agentic runtime. The persona can call native actions and remote MCP tools inside a bounded reasoning loop, with focused sub-agent delegation.
• OpenAI-compatible API. OpenAI-compatible clients can reach the active persona through the project's API server.
• Media and plugin extensions. Voice, speech-to-text, vision, scheduled events and a persistent terminal arrive as modular subsystems and plugins.

Why Persistent Persona State Matters

Most AI characters are only as consistent as the chat tab they live in. Close it, and the persona is gone. SyntH treats the persona as the durable thing and the chat interface as something replaceable, which is what makes swapping engines, answering on Discord, or plugging in an OpenAI-compatible client possible without the character losing its thread.

For anyone building a companion, a roleplay bot or a long-running assistant, that is the difference between a gimmick and something that remembers you.