This article argues that the Unix philosophy of 'everything is a file' should really be understood as 'everything is a stream,' illustrating how streams underpin foundational computing concepts from Turing machines to LLMs. It contrasts plugin architectures (where everything can be swappable) with the necessity of a non-pluggable core that defines the system's behavior, suggesting that the most valuable feedback loops occur at the malleable surface while the agent core requires expensive verification.