Architecture Decisions

Relevant source files

ADRs record why major choices were made: status, context, decision, alternatives, consequences and supersession. An accepted ADR may name an implementation gap, but it is not an implementation manual or a substitute for the current architecture docs. In the repository’s authority order, accepted ADRs rank directly below the generated reference tables and above prose architecture docs.

ADR	Title	Status	Date	One-line summary
0001	Runtime scheduling, preemption, interrupts and lock ordering	Accepted with implementation gap (reschedule IPI pending)	2026-07-14	Per-CPU run queues, bounded stealing, generation-checked waits, strict lock ranks, no logging in hot paths
0002	Kernel error policy	Accepted	2026-07-14	Errors classified by boundary; typed errors only; publish after fallible preparation or roll back
0003	Supported target and feature matrix	Accepted	2026-07-14	x86_64 QEMU supported; Pi 5 and RP2040 supported after HIL; `virt` and RISC-V experimental; signed-only production
0004	BPF JIT policy	Accepted	2026-07-14	v1.0 is interpreter-only; any future JIT needs a superseding ADR meeting six conditions

Design documents follow a separate lifecycle under docs/design/: active/ (under discussion or implementation), accepted/ (reasoning retained after implementation), rejected/. On main all three contain only their README, so no design documents are currently open, accepted or rejected there.