What is syscall-agent?

syscall-agent is a coding agent written in pure C that runs from a single compiled binary. It connects to OpenRouter, a service that routes requests to various AI language models, and uses a tool-calling loop to carry out tasks, reading and writing files, searching the web, running commands, doing DNS lookups, checking network connectivity, and watching for file changes. Rather than relying on a runtime or framework, it implements its capabilities using OS-level system calls directly: things like fork, execvp, mmap, rename, getaddrinfo, and non-blocking sockets. The agent keeps persistent notes in a plain Markdown file called MEMORY.md, with locking to prevent corruption when appending. File writes are done atomically using a temporary file that gets renamed into place. For reading large files, it uses mmap-backed range reads instead of loading entire files into memory. You can run it as a plain command-line tool by passing a question or task as an argument, or open an interactive terminal interface with the --tui flag. The TUI shows model responses as they stream in, supports real-time tool call display, and includes a live model picker that fetches the current list of models from OpenRouter. Subprocess tools that execute local commands are disabled by default and must be opted into explicitly via a flag. It runs on macOS, Linux, and Android through Termux, the terminal environment for Android. Android users get additional tools for reading battery status, Wi-Fi details, and clipboard content through Termux's device API. Dependencies are a C11 compiler, make, and libcurl. The full README is longer than what was provided.