14 posts in, back to the big picture: append-only context, compaction strategy split, three-layer approval, KDL rule tree, session tree/fork are the five most borrowable; snapcompact, metaharness self-built infra are over-engineered; looplane shouldn't self-build full provider catalog, full TUI, or full collab yet. Philosophy diff: omp = batteries-included in-process, looplane = minimal + external runtime.
Treat pi as a black box first: 4 run modes, session tree persistence, mid-conversation model switching, Enter vs Alt+Enter message interjection, /tree branch navigation. Builds intuition for the architecture parts that follow.
Why Pi has no built-in permission system, Gondolin Extension (micro-VM), Docker mode, OpenShell policy-controlled sandbox, permission model philosophy, three containerization patterns, security boundary comparison, micro-VM vs container vs process isolation.
Complete Extension system analysis: Extension interface definition, onLoad/onUnload lifecycle, four major Hooks (onAgentStart/onBeforeToolCall/onAfterToolCall/onTurnEnd), five extension points (tools/commands/keybindings/ui/settings), ExtensionRunner load order and dependency resolution, ExtensionAPI capabilities, Dynamic Border, Widget, Dialog, Selector UI components, Extension inter-communication, hot reload mechanism, official example Extensions.
From user-visible features into architecture: 7 npm packages with clear boundaries, one-way dependency flow, why pi-tui/pi-telemetry have zero deps, how pi-ai encapsulates provider details, lockstep versioning avoiding diamond deps. Builds an 'outside-in' mental model.
This 17-part series takes you from CLI user perspective through pi-mono's Agent Loop, Session Tree, Tool System, Extension System, TUI Architecture, Remote Session, Telemetry, Compaction, and Release process. Ideal for developers wanting to self-host agents, research agent architecture, or contribute to pi.
The first observation of 'What course articles do you have?' was contaminated by an old cache entry. A real cache miss retrieved all four university maps but spent 51.169 seconds across three Writer and Critic passes; after catalog-specific retrieval and review fixes, one uncached production observation passed q21 in 26.821 seconds.
Ask AI first extracts intent, complexity, and 1–4 search terms. It then routes across metadata, BM25, Vectorize, and RRF; a retry adds Critic gaps and disables the first-pass-only BM25 short circuit.