Update openspec with clarified design decisions

openspec/changes/declpac-cli-tool/specs/aur-sync/spec.md

@@ -1,23 +1,30 @@
 ## ADDED Requirements
 
-### Requirement: Can handle AUR packages with pacman fallback
+### Requirement: Handle AUR packages with fallback and upgrade
 
-The system SHALL attempt to install AUR packages by first trying pacman
-repositories, then falling back to AUR when pacman fails, and finally reporting
-errors for packages still missing.
+The system SHALL first attempt to install packages via pacman, then fall back
+to AUR for packages not found in repos, and upgrade AUR packages to
+latest versions.
 
-#### Scenario: Install from pacman first
+#### Scenario: Try pacman first
 - **WHEN** package is in pacman repositories
-- **THEN** system shall install via pacman
+- **THEN** install via pacman -Syu
 
 #### Scenario: Fall back to AUR
 - **WHEN** package is not in pacman repositories but is in AUR
-- **THEN** system shall attempt installation via makepkg (direct AUR build)
+- **THEN** query AUR via Jguer/aur library
+- **AND** build and install with makepkg -si
+
+#### Scenario: Upgrade AUR packages
+- **WHEN** AUR package is already installed but outdated
+- **THEN** rebuild and reinstall with makepkg to get latest version
 
 #### Scenario: Report error for missing packages
 - **WHEN** package is not in pacman repositories or AUR
-- **THEN** system shall report error and print to stderr
+- **THEN** print error to stderr with package name
+- **AND** exit with code 1
 
-#### Scenario: Continue for remaining packages
-- **WHEN** some packages are installed and some fail
-- **THEN** system shall continue installation process for successful packages
+#### Scenario: AUR build failure
+- **WHEN** makepkg fails to build package
+- **THEN** print makepkg error to stderr
+- **AND** exit with code 1