# Prometeu Runtime — Architecture (Reset Invariants)

This document captures the high-level invariants for the reset cycle. It is a stub and will
evolve as we formalize the new ISA/VM specs. The goal is to define non-negotiable properties
that guide refactors without forcing legacy compatibility.

Core invariants
---------------
- Stack-based VM with heap-allocated objects.
- Garbage Collection happens at safepoints, primarily at `FRAME_SYNC`.
- Closures are first-class (user functions). Syscalls are callable but not first-class values.
- Coroutines are the only concurrency model.
- No backward compatibility: old bytecode formats, shims, or legacy bridges are out of scope.

Scope of this stage
-------------------
- Establish tooling baselines (fmt, clippy, CI) and minimal smoke tests.
- Avoid encoding legacy ISA semantics in tests; keep tests focused on build confidence.
- Production code must remain free from test-only hooks; use dev-only utilities for determinism.

Out of scope (for now)
----------------------
- Detailed ISA definition and instruction semantics beyond what is needed to compile and run
  smoke-level validations.
- Performance tuning or GC algorithm selection.