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Graphical shell (executable) ​

The graphical shell executable is the session shell that transitions from login to desktop views.

Role ​

  • Owns login UI, session activation, and desktop/home shell composition.
  • Sets task-level session environment (User) after successful login.

Startup and lifecycle ​

  1. Parses startup args (--show-keyboard).
  2. Builds Shell with Layout and Login components.
  3. Runs loop: layout tick -> login event handling -> post-login desk/home activation.
  4. Continues desk event handling until shell loop terminates.

Runtime integration points ​

  • ExecutableTrait for launcher integration.
  • Context-provided users manager to map the logged user ID to a user name.
  • Context-provided task manager to publish the session user into the task environment.
  • Graphics manager/LVGL wrappers for UI object/event handling.

Data and control flow / VFS touchpoints ​

  • Input: CLI flags and UI events.
  • Primary control flow is event-driven within one shell loop.
  • VFS touchpoints occur indirectly through components such as desktop shortcuts (implemented in submodules), not in top-level loop itself.

Concurrency and event-loop model ​

  • Single periodic loop with task::sleep(Duration::from_millis(50)) cadence.
  • No internal multi-task fan-out in main loop; concurrency is delegated to underlying graphics/task systems.

Failure semantics ​

  • Argument parse failures are printed to stderr and return non-zero.
  • Environment-variable update failures propagate via Error::FailedToSetEnvironmentVariable.
  • UI initialization failures (Layout::new, Login::new, Desk::new, Home::new) propagate as executable error.

Contract vs implementation ​

  • Contract: graphical shell executable starts a login-driven user session loop.
  • Current implementation: explicit login-first flow that instantiates desk/home only after authentication and publishes User env variable.

Operational limitations ​

  • Loop cadence is fixed (50 ms sleep), which trades responsiveness for predictable CPU usage.
  • Session state is task-environment-based; cross-task session propagation relies on external task model behavior.

References ​