---
id: PLN-0053
ticket: system-os-service-ownership-and-module-layout
title: Move Logging Ownership To SystemOS
status: done
created: 2026-05-14
ref_decisions: [DEC-0024]
tags: [runtime, os, services, module-layout, vm, window-manager, logging]
---

## Briefing

Move `LogService` ownership from `VirtualMachineRuntime` to `SystemOS`, while
allowing VM execution code to use OS logging through an explicit reference or
handle.

## Source Decisions

- `DEC-0024`: `LogService` SHALL move from `VirtualMachineRuntime` to
  `SystemOS`; VM execution MAY use an explicit OS logging reference or handle
  but MUST NOT own logging.

## Target

Make logging an OS-owned service and reduce `VirtualMachineRuntime` to a user of
logging rather than its owner.

## Dependencies

- Source decision: `DEC-0024`.
- Depends on `PLN-0051`.
- May run after or alongside `PLN-0052`, but code integration is simpler after
  `SystemOS` service ownership is established.

## Scope

- Add `LogService` ownership to `SystemOS`.
- Remove `log_service: LogService` from `VirtualMachineRuntime`.
- Update VM runtime methods that read/write logs to receive logging access from
  `SystemOS` or a narrow explicit handle.
- Update construction paths so `LogService::new(4096)` is owned by `SystemOS`.
- Update tests that currently inspect runtime-owned logs.

## Out of Scope

- Do not change log capacity or log record semantics.
- Do not change VM syscall behavior except for the ownership path.
- Do not introduce compatibility accessors that imply VM ownership.
- Do not move filesystem or memcard ownership in this plan.

## Execution Plan

1. Add a `LogService` field to `SystemOS` and initialize it in `SystemOS::new`.
2. Remove `LogService` initialization and storage from
   `VirtualMachineRuntime::new`.
3. Update VM logging call paths in `dispatch`, `tick`, lifecycle, and tests to
   use OS-owned logging.
4. If borrow constraints require it, introduce a narrow logging handle/reference
   parameter at the call boundary instead of giving the VM ownership.
5. Update all tests that assert logging behavior.
6. Run formatting and tests.

## Acceptance Criteria

- `VirtualMachineRuntime` no longer stores `LogService`.
- `SystemOS` owns `LogService`.
- VM execution can still emit and expose logs through the existing behavior.
- No compatibility API suggests that logging remains VM-owned.
- Existing logging tests pass or are updated to assert OS ownership.

## Tests / Validation

- Run `cargo test -p prometeu-system`.
- Include focused tests covering VM log writes and reads after ownership moves
  to `SystemOS`.

## Risks

- Borrowing constraints around `NativeInterface` may require a narrow access
  pattern rather than simply borrowing all of `SystemOS`.
- Tests that currently construct only `VirtualMachineRuntime` may need to move
  to `SystemOS` construction to reflect the new owner.

## Affected Artifacts

- `crates/console/prometeu-system/src/os/system_os.rs`
- `crates/console/prometeu-system/src/services/vm_runtime/**`
- Tests under the VM runtime module