Two memory primitives with different lifecycle scopes

Primitives used: persona · memory

// The closed memory lifecycle catalog:
//   ephemeral  — single-turn; cleared as the writing step returns
//   none       — alias for ephemeral; explicit "intentionally amnesiac"
//   session    — lives across the conversation; cleared on disconnect
//   persistent — survives reconnect, scoped by tenant + user

persona Tutor {
    domain: ["education"]
    tone: friendly
    confidence_threshold: 0.7
    cite_sources: false
}

// Per-turn scratch — gone the moment the step returns.
memory ScratchPad {
    store:     ephemeral
    retrieval: exact
}

// Lives for the duration of the conversation.
memory SessionState {
    store:     session
    retrieval: semantic
}

// Survives reconnect — tenant + user scoped.
memory StudentProgress {
    store:     persistent
    backend:   pgvector
    retrieval: semantic
    decay:     never
}