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+Sketch is an agentic coding tool with a two-layer architecture:
+
+1. Outer sketch: CLI command running on user's machine
+2. Inner sketch: Binary running inside Docker containers for isolated work
+
+Both layers use the same entrypoint (cmd/sketch). Outer sketch sets up containerization and starts inner sketch. Changes made in inner sketch are pushed via git to outer sketch.
+
+## Core Packages
+
+- termui, webui: Both interfaces operate at all times
+- loop: Central state machine that manages agent conversation flow
+- claudetools: Tool calls available to LLMs
+- llm: Common LLM interface and conversation management, with provider-specific integrations
+
+## Development Guidelines
+
+- Do NOT git add or modify .gitignore, makefiles, or executable binaries unless requested
+- When changing tool schemas, update both termui and webui
+- For unsafe/recursive development, use `-unsafe` flag
+- Unless explicitly requested, do not add backwards compatibility shims