Mostly-Harmless_Second-Brain

Use Open Second Brain to read, write, and maintain an agent-owned second brain in an Obsidian-compatible Markdown vault. The agent owns one top-level directory (`Brain/`). User-authored notes live wherever the operator names them and are read-only inputs when listed in `notes.read_paths`.

Use when the user explicitly mentions codegraph, asks structural code questions such as callers/callees/impact, asks where a symbol is defined, asks what breaks if a symbol changes, or asks for an architectural overview of a code repository. Skip for prose-only or vault-only questions.