Zero is ~200k+ lines of Go across 800+ files with no internal architecture map. PRD.md is a product/requirements doc and AGENTS.md is a user-facing extension guide — neither explains the runtime spine a new contributor has to learn: the agent loop, the TUI↔agent callback bridge, the tool-execution lifecycle, compaction, and the package map.
A maintainer-oriented "how it works" guide fills that gap. #539 adds one.
Zero is ~200k+ lines of Go across 800+ files with no internal architecture map. PRD.md is a product/requirements doc and AGENTS.md is a user-facing extension guide — neither explains the runtime spine a new contributor has to learn: the agent loop, the TUI↔agent callback bridge, the tool-execution lifecycle, compaction, and the package map.
A maintainer-oriented "how it works" guide fills that gap. #539 adds one.