# Controller guidance

Inherit the root and package guides. This scope preserves controllers as process-lifetime authorities for shared
transitions. Services own execution resources; existing prompts are presentation compatibility paths.

## Shared state authorities

- Controllers own process-lifetime shared state and transition policy. They coordinate injected repositories/services
  and publish structured Qt signals. New behavior delegates presentation and execution resources to their owners;
  existing host-setting prompts do not justify moving network replies, core processes, or pools into controllers.
- `ConnectionController` is the sole connection state machine. A GUI start remains `Connecting` while one
  generation-checked `ConnectionManager` transaction acquires readiness/TUN resources. The selected live profile is
  exposed during `Connecting`; successful runtime commit precedes System Proxy setup and `Connected`. Failure resets
  the active profile. Disconnect/reconnect cancels the exact in-flight generation and ignores stale completion.
- Preserve state and signal ordering, interaction gating, the exact selected `ServerProfile`, runtime snapshots,
  reconnect preference, and rollback after validation, runtime, TUN, System Proxy exceptions, cancellation, or unexpected-exit
  failure. Worker/native callbacks cross to the controller’s Qt thread before transition.
- The active live profile is not the prepared document used by an already-started runtime. Resolve identity and
  generation before changing state or host effects, and preserve typed runtime failures; cancellation and supersession
  are not generic connection errors.
- `RoutingController` owns available capability options plus selected/persisted routing. Distinguish a newly
  selected repository profile from the active-profile reference and the independent runtime document; changes use
  controlled reconnect, not mutation of the running document. Capability refresh prefers the active profile and
  otherwise the repository's activated profile. Normalizing the displayed option does not itself persist a new
  preference; explicit selection owns that mutation. User-defined routing labels are not translatable UI literals.
- `SettingsController` is the shared policy path used by Home, Settings, tray, and platform integration. Startup
  registration persists only after host success; other preferences may apply immediately or on the next connection.
  Preserve each setting's actual application timing instead of imposing one transaction order on all preferences.
- System Proxy configuration is best effort. Its helper logs host failures; an explicit False return does not roll
  back an otherwise usable committed runtime or prevent Connected. Preserve exception-path recovery separately.
  Exercise actual helper results with mocked OS boundaries; Connected does not guarantee the OS proxy was applied.

## Verification and evolution

- Test exact states and signal counts for async success, invalid input, supersession, cancellation, partial
  acquisition, System Proxy failure, unexpected exit, routing refresh/reconnect, startup restoration, failed host
  settings, missing partial-startup dependencies, and repeated shutdown. If ownership moves deliberately, update
  this guide and the affected controller tests instead of keeping a compatibility controller as a second authority.
  Start with `tests/test_controllers.py`, `tests/test_connection_startup_async.py`, and the shared-state cases in
  `tests/test_qt_interactions.py`.