agentc - a minimal agent in C: under 1 MB, no runtime

Hi everyone, just sharing a small project: A minimal, extensible coding agent, built around the question of what an agent's extension surface should actually be. - MCP for anything external: tools, prompts and resources over stdio, with reconnect behind capped exponential backoff - A versioned C ABI (include/agentc_ext.h) for anything that needs to be in-process: sync or async tools, providers, models, and prompt/theme roots - Extensions either link into the binary or load at runtime on macOS/Windows; C and Rust reference extensions included - Session state is JSONL, config is JSONC, and there's no cross-agent file-format compatibility to worry about - One static binary under 1 MB, no libc; ~0.7 MB RSS at startup, ~2–4 MB idle MIT. Would like to hear how others are drawing the line between MCP and in-process extensions. Would love for anyone on macOS or Windows to try it: Linux is tested end to end, but those two have only run in CI so far. Binaries are up for Linux (x64, arm64, riscv64), Windows (x64, arm64) and macOS (arm64).