# Retired Decisions 004-005 (Historical Notes)

This file keeps historical rationale from decisions that were retired after being absorbed by specs.

Status: pedagogical / historical (not normative).

## Mapping

- Retired `004-host-fault-taxonomy.md`
  - Canonical source now: `../specs/16a-syscall-policies.md`
- Retired `005-v1-vm-owned-input-intrinsics-and-language-agnostic-surface.md`
  - Canonical sources now:
    - `../specs/06-input-peripheral.md`
    - `../specs/16-host-abi-and-syscalls.md`
    - `../specs/16a-syscall-policies.md`

## Historical Rationale Snapshot

### 1) Why input left syscall path in v1

- repeated input reads through syscall would force large value transport;
- deterministic frame snapshot works better as VM-owned intrinsic surface;
- frontend syntax should stay language-specific while VM contract stays language-agnostic.

### 2) Why fault taxonomy was tightened

- operational domain outcomes should be returned as `status`;
- `Trap` should represent structural ABI misuse from guest side;
- `Panic` should represent runtime invariant break;
- broad `Unavailable` usage was causing severity ambiguity.

## Practical Outcome

- Input is VM-owned and deterministic per logical frame.
- Host-backed syscall ABI remains structurally stable.
- Domain agendas now anchor fault discussions on spec `16a`, not on retired decisions.