# Phase 004 Execution

## Scope
- Added fuel and maintenance event creation from the vehicle detail page.
- Added nested event routes and focused create controllers.
- Added odometer update behavior for fuel and maintenance entries.
- Added placeholder event attribution until Phase 005 authentication exists.
- Added request and model specs for the new behavior.

## Changes
- Added nested `fuel_entries#create` and `maintenance_entries#create` routes under vehicles.
- Added `FuelEntriesController` for creating fuel entries from a vehicle page.
- Added `MaintenanceEntriesController` for creating maintenance entries from a vehicle page.
- Added a private `unknown_user` controller helper that looks up `unknown@example.invalid`.
- Added an idempotent `Unknown User` seed in `db/seeds.rb` for temporary Phase 004 attribution.
- Updated `vehicles#show` setup to build form objects and eager-load event users.
- Added fuel and maintenance forms to `vehicles#show`.
- Added inline validation error display for both event forms.
- Added maintenance type selection from the vehicle's existing maintenance schedules.
- Disabled maintenance entry creation in the UI when a vehicle has no maintenance schedules.
- Added `Updated by` columns to fuel and maintenance history tables.
- Added fuel-entry validation rejecting odometer readings lower than the vehicle current odometer.
- Added vehicle odometer updates when saved fuel or maintenance entries have newer odometer readings.
- Added a Stimulus controller that warns when a maintenance odometer is more than 500 miles behind the current vehicle odometer.
- Added server-side flash warning and application log warning for maintenance entries more than 500 miles behind the current vehicle odometer.
- Hardened temporary `Unknown User` attribution so event creation creates the placeholder if the seed has not been run.
- Added a user-visible warning path for attribution setup failures instead of raising a server error.

## Decisions
- Phase 004 uses `Unknown User` for event attribution because Phase 005 will add actual authentication and session identity.
- `Unknown User` is seeded instead of silently created by controllers so missing setup is visible.
- Controllers also create `Unknown User` as a runtime fallback because a missing seed should not produce a 404/server error for users.
- Fuel entries below the current vehicle odometer are rejected.
- Maintenance entries below the current vehicle odometer are allowed because paperwork may be entered later.
- Maintenance entries update the vehicle odometer only when their odometer is newer.
- Maintenance entry names must match an existing maintenance schedule for the vehicle.
- Client-side maintenance odometer warnings are advisory only; server-side logging is the durable audit trail.

## Phase 005 Follow-Up
- Replace `Unknown User` attribution with the authenticated/current session user.
- Remove or stop using the temporary `Unknown User` seed once all event creation requires an identified user.

## Verification
- Passed: `bundle exec rspec spec/models/fuel_entry_spec.rb spec/requests/vehicles_spec.rb`
- Passed: `bundle exec rspec`
- Passed: `bin/rubocop app/controllers/application_controller.rb app/controllers/vehicles_controller.rb app/controllers/fuel_entries_controller.rb app/controllers/maintenance_entries_controller.rb app/models/fuel_entry.rb spec/models/fuel_entry_spec.rb spec/requests/vehicles_spec.rb db/seeds.rb`
- Passed after attribution hardening: `bundle exec rspec spec/requests/vehicles_spec.rb`
- Passed after attribution hardening: `bundle exec rspec`
- Passed after attribution hardening: `bin/rubocop app/controllers/application_controller.rb app/controllers/fuel_entries_controller.rb app/controllers/maintenance_entries_controller.rb spec/requests/vehicles_spec.rb`