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Mandy is a voice- and chat-agent runtime. A trigger (phone call, WhatsApp or SMS message, widget visitor, API request) starts a session; a flow runs to completion, calling swappable speech and language providers as it goes.

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The pieces

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Session lifecycle

From a trigger to an active voice conversation: Text channels (WhatsApp, SMS, widget chat) skip the media path: the inbound message is handed to the flow executor directly and the reply is delivered through the channel adapter. The flow definition is the same either way. The flow executor is stateless per request — every invocation reconstructs state from PostgreSQL. A long conversation runs as many short executor calls, driven by inbound events (transcripts, tool callbacks, child-flow completions).

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Provider resolution

Each flow selects its STT, TTS, and LLM providers. Configuration for the selected provider merges three layers: Config precedence: flow > organization > provider defaults. The organization supplies credentials (API keys) and shared defaults; the flow picks the provider and overrides tuning per use case. Missing required secrets fail the trigger with HTTP 412 before the agent worker is dispatched — preventing opaque mid-call SDK errors.

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Channels

Conversations run over eight channel types — phone (SIP), web widget (text + voice), WhatsApp, SMS, API, store-and-forward audio clips, child-flow sessions, and Telegram (planned). Each channel declares its capabilities (addressability, persistence, outbound initiation) and its reachability window. Full detail: Channels. Channel-specific prompt hints are injected into the LLM context so a voice flow gets speech-rendering guidance and a chat flow gets markdown guidance — same flow definition, different rendering hint.

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Memory

  • The brain — one knowledge graph per organization with a personal scope per person and a shared company scope. Conversations become verbatim episodes; extraction turns them into atomic, time-stamped facts about people, assets, locations and processes, each linked to its evidence. External feeds (scanners, machine state, location) push live facts without a model in the loop.
  • Persistent variables — flow variables marked as persistent survive across sessions for the same user.
  • Knowledge bases — per-organization document collections, retrievable through the rag flow node.
Identity is unified across channels: a caller’s phone number and a messaging identity on the same number converge on one person, and an anonymous web visitor’s brain is merged into their verified identity once they are identified.