Build a Head-of-Design Sub-Agent — From Vanilla HTML to a Composing Designer in One Session

Paste this into Claude Code, Cursor, or Aider and it interviews you about the agent you already have — its stack, whether it remembers anything today, whether its voice drifts over long chats — then does a strictly read-only pass over your codebase to see how it actually thinks before it changes a line. Only then does it help you build the brain that runs Trillion: a personality that lives in an editable file and reloads the moment you save it, a two-block system prompt that keeps the whole personality resident every single turn without ballooning your bill, an always-loaded core-knowledge layer so it never re-asks what it should already know, working memory that persists and recovers across sessions, and a typed, file-backed long-term memory with semantic recall — written both by the agent's own hand through tools and by an automatic end-of-session extractor that dedupes before it saves. It finishes with a self-knowledge layer so the agent knows what it is, and a personality checkpoint that stops it sliding into generic-assistant voice deep in a conversation. Interview first, map second, then build tier by tier — each tier ships independently with its own verification.