# SlOS

> A from-scratch OS built on a replayable causal event graph, with time-travel debugging and location-transparent actors over an encrypted mesh.

- Status: active
- Started: 2026-02-23
- Category: Systems & Languages
- Tags: os, systems, c, assembly

SlOS is a hobby operating system I'm writing from scratch — but the angle that makes it interesting is time. Every kernel event (task creation, faults, messages, network operations) becomes a node in a causal event graph, so the system can answer "why did this happen?" and replay its own decisions. Named timelines let you rewind, fast-forward, and reconstruct past state instead of just reading a snapshot, with a `why` / `rewind` / `replay` style of time-travel debugging.

It's also a distributed actor OS. Location-transparent actors pass typed messages that route to local or remote nodes the same way, over an encrypted mesh (Noise_XX handshake, ChaCha20-Poly1305, SPIFFE identities). That transparency goes surprisingly far: you can run DOOM on one machine and watch — or play — it from another, with the framebuffer streamed as XOR-delta + RLE over the mesh.

Underneath it's a real kernel: multi-architecture (x86-32, x86-64, ARM64/Pi 5), a preemptive priority scheduler, paging and a heap allocator, VirtIO block and network drivers, a TCP/IP stack with DHCP and an in-kernel HTTP server, a persistent filesystem, an ELF loader for ring-3 programs, and a Linux-flavored shell with 100+ commands, pipes, and its own `slosh` scripting language. When a CPU exception fires it even drops into a "Kernel Surgeon" you can use to poke memory and resume — instead of panicking.