One brain, every conversation.

Two transports, one set of decisions

There is exactly one place that decides what Lewis says. The browser demo and the phone are both thin wrappers around it: they differ in how state travels, not in what happens.

In a browser, the conversation state is handed back and forth with each turn. A phone has no browser state to hand back, so the same payload lives in a row. That is the whole difference.

It matters because of what it prevents: a “quick fix” made in one surface that silently does not exist on the other. When the fix lives in the engine, the phone gets it without a second edit, and a field added to the engine and forgotten in the reducer fails a test rather than vanishing on one transport.

What lives in there

• The rails. Block, hold, allow, on every send. Guardrails.
• Taste. How it hears “more modern” or “I don’t like the interior”: evidence that reorders, never a filter, and never quoted back at somebody as if it were a fact about a home.
• Proximity. Exact distance free; a travel time only from a provider that traced streets.
• Watches. The one thing in the product that speaks first: somebody likes a place, turns down an introduction, and Lewis offers to keep an eye on it.
• Rooms. A group chat is not a louder one-to-one. It is always the buyer side, it answers some of what it hears and records all of it, and a failed gate means silence rather than a chattier bot.
• The log. Every decision, appended. Event log.

The parts that are refusals

Half of what is in the engine is a decision not to act.

A room resolves no identity, because a bare “yes” in a group has no unambiguous author, and “never guess on approvals” cannot be made to work with three people talking. So the agent side is refused in a room rather than made to work badly, and a room gets the half that is genuinely better with more people in it.

Taste never reaches a caption, so the product physically cannot claim a home is “modern” off an inference over marketing copy.

A travel time has no detour multiplier. East Boston to Back Bay is three miles straight and twenty-odd around the harbour, and there is no coefficient that fixes that.

A search can fail with results still in it. Twenty homes in range that are all the thing somebody already rejected is not an empty list; it is a useless one, and the product served from it without noticing. So the sentence carries arithmetic: “13 of the places in your range are modern…” rather than an opinion about how picky somebody is being.