A cast that keeps living when you close the app

A chat window, and then nothing

• A backend, a client, and a character who could hold a conversation.
• Then it sat for six weeks. It worked, but it was just a chat window — the characters forgot everything the moment you left.

One source of truth

• The World Journal. Every event in the world writes to one journal, and every prompt reads from it. This is the whole fix for the thing that ruined the apps I was modelling against: the story and the chat can no longer contradict each other, because there is only one story.
• Memory. Every few turns, a cheap model reads the conversation and extracts what the character now knows about you, plus one sentence on where you stand. That sentence goes into every future prompt.
• The world tick. Time passing generates private conversations between characters, posts, comments and unprompted messages to you. Never on a timer — only when you open the app after a gap, or ask for it. The world moving should never quietly spend money.
• Situations. Events you write yourself that colour every prompt until you end them.
• Relationships are a sentence, not a score. Rebuilt as meters two days later — see below.

Twelve people, and the small things that sell it

• Twelve characters, each with a history, a personality, a way of speaking, and opinions about the other eleven. The full portrait goes into that character's own conversations; a compact version goes to the narrator that runs the world.
• Replies arrive as one to three separate bubbles, revealed one at a time, instead of a single essay. Cheapest realism win of the whole project.
• Every message you send carries its real timestamp into the prompt, so characters notice it's late, or that you've been gone three days.
• Per-character notes you can write yourself, which override everything else in that character's prompt.
• Hand-drawn emblem avatars rather than faces — a deliberate choice, and one I'd make again.

Long memory, a self-moving world, and a budget

• Long-term memory. Old journal entries fold into a rolling chronicle instead of being dropped, so the world still remembers last week without paying to re-read it every time.
• The world moves on its own. A tick can now start its own situation or shift a relationship — nobody has to author every event. Come back after a day away and it runs the catch-up you missed.
• A group chat for the whole household, which only fires when something actually happens. It stays quiet otherwise, on purpose.
• A daily spend cap. Every action's cost is tracked and totalled; past the cap, everything optional is refused and only your own conversations still work. A usage screen shows today against the cap.
• Meters — friendship and romance, 0 to 100, with named stages. I'd explicitly rejected points two days earlier and changed my mind, with one condition: every movement is logged with the reason it moved, and hurting someone moves it down. Everyone starts at the bottom.

The reversal is the honest bit. "No points, relationships are a sentence" was the right instinct about opaque scores, not about scores. A number you can see the reasons behind turned out to be the thing I wanted all along.