Module relationship 

Relationship familiarity: a light, prompt-level sense of how well the bot “knows” the person it’s talking to, derived from how much history they share (the stored message count). People treat a stranger and an old friend differently; this nudges tone the same way.

Conservative by design: only the extremes (brand-new vs. long-time) inject anything. The broad middle stays silent so we don’t over-prompt.

Functions

familiarity_hint

One-line familiarity guidance for the system prompt, or None for the broad middle where no nudge is warranted.