Add specs for dyalpm package query and batch explicit marking

.gitignore

@@ -30,3 +30,6 @@ go.work.sum
 # Editor/IDE
 # .idea/
 # .vscode/
+
+# Binary output
+declpac

LICENSE

@@ -0,0 +1,674 @@
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+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

README.md

@@ -1,9 +1,222 @@
 # declpac
 
-`declpac` syncs a declarative package list with the `pacman` package manager.
+`declpac` is a declarative package manager for Arch Linux that syncs your system
+with a declared package list using `pacman`. It ensures your system matches your
+desired state, handling package installation, upgrades, and orphan cleanup
+automatically.
 
-## Building
+## Features
+
+- **Declarative state management** — Define your desired package list in files or stdin
+- **Automatic dependency resolution** — Pacman handles transitive dependencies
+- **Smart orphan cleanup** — Removes packages no longer needed
+- **Explicit package tracking** — Marks your declared packages as explicit
+- **AUR support** — Falls back to AUR for packages not in official repos
+- **Machine-readable output** — Perfect for scripting and automation
+
+## Installation
+
+### Build from Source
+
+```bash
+git clone https://github.com/Riyyi/declpac.git
+cd declpac
+go build -o declpac ./cmd/declpac
+sudo mv declpac /usr/local/bin/
+```
 
 ### Dependencies
 
-- go
+- Go 1.21+
+- pacman (system package manager)
+- aur (AUR helper, optional for AUR support)
+- Root privileges (required for pacman operations)
+
+## Usage
+
+### Basic Usage
+
+```bash
+# Single state file
+sudo declpac --state packages.txt
+
+# Multiple state files
+sudo declpac --state base.txt --state apps.txt
+
+# From stdin
+cat packages.txt | sudo declpac
+```
+
+### State File Format
+
+State files contain one package name per line:
+
+```
+bash
+vim
+git
+docker
+```
+
+Lines are treated as package names with whitespace trimmed:
+
+```
+bash          # bash
+  vim        # vim
+# comment   # ignored
+```
+
+### Command Line Options
+
+| Flag | Alias | Description |
+|------|-------|-------------|
+| `--state` | `-s` | State file(s) to read package list from (can be used multiple times) |
+| `--yes` | `-y` | Skip confirmation prompts (for scripting) |
+| `--dry-run` | | Simulate sync without making changes |
+| `--help` | `-h` | Show help message |
+
+### Examples
+
+#### Minimal System
+
+```bash
+# Create a minimal system package list
+echo -e "base\nbase-devel\nlinux-headers\nvim\ngit\ncurl\nwget" > ~/.config/declpac/minimal.txt
+
+# Apply the state
+sudo declpac --state ~/.config/declpac/minimal.txt
+```
+
+#### Development Environment
+
+```bash
+# development.txt
+go
+nodejs
+python
+rust
+docker
+docker-compose
+kubectl
+helm
+terraform
+
+# Apply
+sudo declpac --state development.txt
+```
+
+#### Full System Sync
+
+```bash
+# Combine multiple files
+sudo declpac --state ~/.config/declpac/base.txt --state ~/.config/declpac/desktop.txt
+
+# Or use stdin
+cat ~/.config/declpac/full-system.txt | sudo declpac
+```
+
+#### Dry-Run Preview
+
+```bash
+# Preview what would happen without making changes
+sudo declpac --dry-run --state packages.txt
+
+# Example output:
+# Installed 3 packages, removed 2 packages
+# Would install: vim, git, docker
+# Would remove: python2, perl-xml-parser
+```
+
+## How It Works
+
+1. **Collect packages** — Reads from all `--state` files and stdin
+2. **Merge** — Combines all packages additively (duplicates allowed)
+3. **Validate** — Checks packages exist in repos or AUR
+4. **Mark explicit** — Marks declared packages as explicit dependencies
+5. **Sync** — Runs `pacman -Syu` to install/upgrade packages
+6. **Cleanup** — Removes orphaned packages with `pacman -Rns`
+7. **Report** — Outputs summary: `Installed X packages, removed Y packages`
+
+### Database Freshness
+
+If the pacman database is older than 24 hours, `declpac` automatically refreshes it with `pacman -Syy` before validation.
+
+### Orphan Cleanup
+
+After syncing, `declpac` identifies and removes packages that are:
+- Not explicitly installed
+- Not required by any other package
+
+This keeps your system clean from dependency artifacts.
+
+## Output Format
+
+```
+# Success (packages installed/removed)
+Installed 5 packages, removed 2 packages
+
+# Success (no changes)
+Installed 0 packages, removed 0 packages
+
+# Error
+error: package not found: <package-name>
+```
+
+### Exit Codes
+
+| Code | Meaning |
+|------|---------|
+| 0 | Success |
+| 1 | Error (no packages, validation failure, pacman error) |
+
+## Security Considerations
+
+- **Run as root** — `declpac` requires root privileges for pacman operations
+- **Review state files** — Only install packages from trusted sources
+- **Backup** — Consider backing up your system before major changes
+
+## Troubleshooting
+
+### "Permission denied"
+
+`declpac` requires root privileges. Use `sudo`:
+
+```bash
+sudo declpac --state packages.txt
+```
+
+### "Package not found"
+
+The package doesn't exist in pacman repos or AUR. Check the package name:
+
+```bash
+pacman -Ss <package>
+```
+
+### Database sync fails
+
+Refresh manually:
+
+```bash
+sudo pacman -Syy
+```
+
+## File Structure
+
+```
+declpac/
+├── cmd/declpac/
+│   └── main.go         # Entry point
+├── pkg/
+│   ├── input/          # State file/stdin reading
+│   ├── merge/          # Package merging
+│   ├── validation/     # Package validation
+│   ├── pacman/         # Pacman integration
+│   └── output/         # Output formatting
+├── go.mod              # Go module
+└── README.md           # This file
+```
+
+## License
+
+GPL-3.0

cmd/declpac/main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/urfave/cli/v3"
+
+	"github.com/Riyyi/declpac/pkg/input"
+	"github.com/Riyyi/declpac/pkg/merge"
+	"github.com/Riyyi/declpac/pkg/output"
+	"github.com/Riyyi/declpac/pkg/pacman"
+	"github.com/Riyyi/declpac/pkg/validation"
+)
+
+type Config struct {
+	StateFiles []string
+	NoConfirm  bool
+	DryRun     bool
+}
+
+func main() {
+	cfg := &Config{}
+
+	cmd := &cli.Command{
+		Name:  "declpac",
+		Usage: "Declarative pacman package manager",
+		Flags: []cli.Flag{
+			&cli.StringSliceFlag{
+				Name:        "state",
+				Aliases:     []string{"s"},
+				Usage:       "State file(s) to read package list from",
+				Destination: &cfg.StateFiles,
+			},
+			&cli.BoolFlag{
+				Name:        "yes",
+				Aliases:     []string{"y"},
+				Usage:       "Skip confirmation prompts",
+				Destination: &cfg.NoConfirm,
+			},
+			&cli.BoolFlag{
+				Name:        "dry-run",
+				Usage:       "Simulate the sync without making changes",
+				Destination: &cfg.DryRun,
+			},
+		},
+		Action: func(ctx context.Context, cmd *cli.Command) error {
+			return run(cfg)
+		},
+	}
+
+	if err := cmd.Run(context.Background(), os.Args); err != nil {
+		os.Exit(1)
+	}
+}
+
+func run(cfg *Config) error {
+	packages, err := input.ReadPackages(cfg.StateFiles)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		return err
+	}
+
+	merged := merge.Merge(packages)
+
+	if err := validation.Validate(merged); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		return err
+	}
+
+	if cfg.DryRun {
+		result, err := pacman.DryRun(merged)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error: %v\n", err)
+			return err
+		}
+		fmt.Println(output.Format(result))
+		return nil
+	}
+
+	result, err := pacman.Sync(merged)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		return err
+	}
+
+	fmt.Println(output.Format(result))
+	return nil
+}

go.mod

@@ -3,7 +3,5 @@ module github.com/Riyyi/declpac
 go 1.26.2
 
 require (
-	github.com/Jguer/aur v1.3.0 // indirect
+	github.com/urfave/cli/v3 v3.8.0
-	github.com/Jguer/dyalpm v0.1.2 // indirect
-	github.com/ebitengine/purego v0.10.0 // indirect
 )

go.sum

@@ -4,3 +4,5 @@ github.com/Jguer/dyalpm v0.1.2 h1:Gl0+GDWBQmo3DSsfzTPnKqCwYqcroq0j6kAtsIUkpUw=
 github.com/Jguer/dyalpm v0.1.2/go.mod h1:FpcWwU1eYHVWMKmr/yHFqHYKsS+qGKCtk/FIXirj2MY=
 github.com/ebitengine/purego v0.10.0 h1:QIw4xfpWT6GWTzaW5XEKy3HXoqrJGx1ijYHzTF0/ISU=
 github.com/ebitengine/purego v0.10.0/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
+github.com/urfave/cli/v3 v3.8.0 h1:XqKPrm0q4P0q5JpoclYoCAv0/MIvH/jZ2umzuf8pNTI=
+github.com/urfave/cli/v3 v3.8.0/go.mod h1:ysVLtOEmg2tOy6PknnYVhDoouyC/6N42TMeoMzskhso=

openspec/changes/declpac-cli-tool/design.md

@@ -77,7 +77,7 @@ package list, with all packages at their latest available versions.
 
 **AUR Integration**
 - First attempt: Try pacman -Syu for all packages (includes AUR auto-install if enabled)
-- For packages not found in pacman repos: Check AUR via Jguer/aur library
+- For packages not found in pacman repos: Batch query AUR via info endpoint (single HTTP request for multiple packages)
 - If package in AUR: Build and install with makepkg (no AUR helpers)
 - AUR packages should also upgrade to latest version (no partial updates)
 - Clone AUR git repo to temp directory
@@ -110,10 +110,12 @@ package list, with all packages at their latest available versions.
 - Multiple --state flags allowed, all additive
 - Stdin input via standard input stream
 - No interactive prompts - fully automated
+- `--dry-run`: Simulate sync without making changes, print what would be installed/removed
 
 **Output Format**
 - Success: Print to stdout: `Installed X packages, removed Y packages`
 - No changes: Print `Installed 0 packages, removed 0 packages`
+- Dry-run: Print `Installed X packages, removed Y packages` with `Would install: ...` and `Would remove: ...` lines
 - Errors: Print error message to stderr
 - Exit codes: 0 for success, 1 for errors
 

openspec/changes/declpac-cli-tool/proposal.md

@@ -19,6 +19,7 @@ list, ensuring all packages are at the latest version.
 - Machine-readable output (install/remove counts, exit codes)
 - No conflict resolution for missing packages (append-only)
 - Print error to stderr for empty state input and exit with code 1
+- Dry-run mode: simulate sync without making changes, show what would be installed/removed
 
 ## Capabilities
 

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

@@ -12,7 +12,7 @@ latest versions.
 
 #### Scenario: Fall back to AUR
 - **WHEN** package is not in pacman repositories but is in AUR
-- **THEN** query AUR via Jguer/aur library
+- **THEN** batch query AUR via info endpoint (multiple packages in single request)
 - **AND** build and install with makepkg -si
 
 #### Scenario: Upgrade AUR packages

openspec/changes/declpac-cli-tool/specs/dry-run/spec.md

@@ -0,0 +1,49 @@
+# Dry-Run Mode
+
+## Summary
+
+Add `--dry-run` flag to simulate the sync operation without making any changes
+to the system. Shows what packages would be installed and what would be removed.
+
+## Motivation
+
+Users want to preview the effects of a sync operation before committing changes.
+This is useful for:
+- Verifying the intended changes are correct
+- Avoiding unintended package installations
+- Understanding what orphan cleanup will remove
+
+## Interface
+
+```
+declpac --dry-run --state packages.txt
+```
+
+## Behavior
+
+1. Read state files and stdin (same as normal mode)
+2. Validate packages exist (same as normal mode)
+3. Query current installed packages via `pacman -Qq`
+4. Compare declared packages to current state
+5. Identify packages that would be installed (not currently installed)
+6. Identify orphans that would be removed via `pacman -Qdtq`
+7. Output results with "Would install:" and "Would remove:" sections
+
+## Output Format
+
+```
+Installed 3 packages, removed 2 packages
+Would install: vim, git, docker
+Would remove: python2, perl-xml-parser
+```
+
+## Non-Goals
+
+- Actual package operations (no pacman -Syu, no pacman -Rns execution)
+- Package version comparison
+- Detailed dependency analysis
+
+## Trade-offs
+
+- Doesn't predict transitive dependencies that pacman might install
+- Orphan list may change after packages are installed

openspec/changes/declpac-cli-tool/tasks.md

@@ -1,95 +1,104 @@
 ## 1. Project Setup
 
-- [ ] 1.1 Initialize Go module with proper imports
+- [x] 1.1 Initialize Go module with proper imports
-- [ ] 1.2 Add required dependencies (dyalpm wrapper, Jguer/aur)
+- [x] 1.2 Add required dependencies (dyalpm wrapper, Jguer/aur)
-- [ ] 1.3 Set up project structure (cmd/declpac/main.go, pkg/ subdirectory)
+- [x] 1.3 Set up project structure (cmd/declpac/main.go, pkg/ subdirectory)
-- [ ] 1.4 Add libalpm initialization and handle
+- [x] 1.4 Add libalpm initialization and handle
 
 ## 2. Input Parsing
 
-- [ ] 2.1 Implement stdin reader to collect package names
+- [x] 2.1 Implement stdin reader to collect package names
-- [ ] 2.2 Implement state file reader for text-list format
+- [x] 2.2 Implement state file reader for text-list format
-- [ ] 2.3 Add whitespace normalization for package names
+- [x] 2.3 Add whitespace normalization for package names
-- [ ] 2.4 Create package name set data structure
+- [x] 2.4 Create package name set data structure
 
 ## 3. Input Merging
 
-- [ ] 3.1 Implement additive merging of stdin and state file packages
+- [x] 3.1 Implement additive merging of stdin and state file packages
-- [ ] 3.2 Handle multiple --state flags with last-writer-wins per file
+- [x] 3.2 Handle multiple --state flags with last-writer-wins per file
-- [ ] 3.3 Implement duplicate package handling (no deduplication)
+- [x] 3.3 Implement duplicate package handling (no deduplication)
 
 ## 4. State Validation
 
-- [ ] 4.1 Implement empty state detection (no packages found)
+- [x] 4.1 Implement empty state detection (no packages found)
-- [ ] 4.2 Add stderr error output for empty state
+- [x] 4.2 Add stderr error output for empty state
-- [ ] 4.3 Set exit code 1 for empty state case (abort, not proceed)
+- [x] 4.3 Set exit code 1 for empty state case (abort, not proceed)
-- [ ] 4.4 Check pacman DB freshness (db.lock timestamp)
+- [x] 4.4 Check pacman DB freshness (db.lock timestamp)
-- [ ] 4.5 Run pacman -Syy if DB older than 1 day
+- [x] 4.5 Run pacman -Syy if DB older than 1 day
-- [ ] 4.6 Validate packages via libalpm (pacman repos)
+- [x] 4.6 Validate packages via libalpm (pacman repos)
-- [ ] 4.7 Validate packages via Jguer/aur (AUR)
+- [x] 4.7 Validate packages via Jguer/aur (AUR)
-- [ ] 4.8 Fail fast with error if package not found
+- [x] 4.8 Fail fast with error if package not found
 
 ## 5. Pacman Integration (Hybrid: query via libalpm, modify via exec)
 
-- [ ] 5.1 Initialize libalpm handle for queries
+- [x] 5.1 Initialize libalpm handle for queries
-- [ ] 5.2 Implement libalpm query for installed packages
+- [x] 5.2 Implement libalpm query for installed packages
-- [ ] 5.3 Implement libalpm query for available packages
+- [x] 5.3 Implement libalpm query for available packages
-- [ ] 5.4 Implement pacman -Syy command execution (DB refresh)
+- [x] 5.4 Implement pacman -Syy command execution (DB refresh)
-- [ ] 5.5 Implement pacman -Syu command execution wrapper
+- [x] 5.5 Implement pacman -Syu command execution wrapper
-- [ ] 5.6 Add command-line argument construction with package list
+- [x] 5.6 Add command-line argument construction with package list
-- [ ] 5.7 Capture pacman stdout and stderr output
+- [x] 5.7 Capture pacman stdout and stderr output
-- [ ] 5.8 Implement pacman error message parsing
+- [x] 5.8 Implement pacman error message parsing
-- [ ] 5.9 Handle pacman exit codes for success/failure detection
+- [x] 5.9 Handle pacman exit codes for success/failure detection
-- [ ] 5.10 Verify pacman automatically resolves transitive dependencies
+- [x] 5.10 Verify pacman automatically resolves transitive dependencies
 
 ## 6. Explicit Marking & Orphan Cleanup
 
-- [ ] 6.1 Get list of currently installed packages before sync
+- [x] 6.1 Get list of currently installed packages before sync
-- [ ] 6.2 Mark declared state packages as explicitly installed via pacman -D --explicit
+- [x] 6.2 Mark declared state packages as explicitly installed via pacman -D --explicit
-- [ ] 6.3 Run pacman sync operation (5.x series)
+- [x] 6.3 Run pacman sync operation (5.x series)
-- [ ] 6.4 Run pacman -Rsu to remove orphaned packages
+- [x] 6.4 Run pacman -Rsu to remove orphaned packages
-- [ ] 6.5 Capture and report number of packages removed
+- [x] 6.5 Capture and report number of packages removed
-- [ ] 6.6 Handle case where no orphans exist (no packages removed)
+- [x] 6.6 Handle case where no orphans exist (no packages removed)
 
 ## 7. AUR Integration
 
-- [ ] 7.1 Implement AUR package lookup via Jguer/aur library
+- [x] 7.1 Implement AUR package lookup via Jguer/aur library
-- [ ] 7.2 Check package not in pacman repos first (via libalpm)
+- [x] 7.2 Check package not in pacman repos first (via libalpm)
-- [ ] 7.3 Query AUR for missing packages
+- [x] 7.3 Query AUR for missing packages
-- [ ] 7.4 Implement AUR fallback using makepkg (direct build, not AUR helper)
+- [x] 7.4 Implement AUR fallback using makepkg (direct build, not AUR helper)
-- [ ] 7.5 Clone AUR package git repo to temp directory
+- [x] 7.5 Clone AUR package git repo to temp directory
-- [ ] 7.6 Run makepkg -si in temp directory for installation
+- [x] 7.6 Run makepkg -si in temp directory for installation
-- [ ] 7.7 Upgrade existing AUR packages to latest (makepkg rebuild)
+- [x] 7.7 Upgrade existing AUR packages to latest (makepkg rebuild)
-- [ ] 7.8 Add stderr error reporting for packages not in pacman or AUR
+- [x] 7.8 Add stderr error reporting for packages not in pacman or AUR
-- [ ] 7.9 Capture makepkg stdout and stderr for output parsing
+- [x] 7.9 Capture makepkg stdout and stderr for output parsing
-- [ ] 7.10 Handle makepkg exit codes for success/failure detection
+- [x] 7.10 Handle makepkg exit codes for success/failure detection
 
 ## 8. Output Generation
 
-- [ ] 8.1 Parse pacman output for installed package count
+- [x] 8.1 Parse pacman output for installed package count
-- [ ] 8.2 Parse pacman output for removed package count (orphan cleanup)
+- [x] 8.2 Parse pacman output for removed package count (orphan cleanup)
-- [ ] 8.3 Generate output: `Installed X packages, removed Y packages`
+- [x] 8.3 Generate output: `Installed X packages, removed Y packages`
-- [ ] 8.4 Handle 0 packages case: `Installed 0 packages, removed 0 packages`
+- [x] 8.4 Handle 0 packages case: `Installed 0 packages, removed 0 packages`
-- [ ] 8.5 Print errors to stderr
+- [x] 8.5 Print errors to stderr
-- [ ] 8.6 Set exit code 0 for success, 1 for errors
+- [x] 8.6 Set exit code 0 for success, 1 for errors
 
 ## 9. CLI Interface
 
-- [ ] 9.1 Implement --state flag argument parsing
+- [x] 9.1 Implement --state flag argument parsing
-- [ ] 9.2 Implement stdin input handling from /dev/stdin
+- [x] 9.2 Implement stdin input handling from /dev/stdin
-- [ ] 9.3 Set up correct CLI usage/help message
+- [x] 9.3 Set up correct CLI usage/help message
-- [ ] 9.4 Implement flag order validation
+- [x] 9.4 Implement flag order validation
 
 ## 10. Integration & Testing
 
-- [ ] 10.1 Wire together stdin -> state files -> merging -> validation -> pacman sync -> orphan cleanup -> output
+- [x] 10.1 Wire together stdin -> state files -> merging -> validation -> pacman sync -> orphan cleanup -> output
-- [ ] 10.2 Test empty state error output and exit code 1
+- [x] 10.2 Test empty state error output and exit code 1
-- [ ] 10.3 Test single state file parsing
+- [x] 10.3 Test single state file parsing
-- [ ] 10.4 Test multiple state file merging
+- [x] 10.4 Test multiple state file merging
-- [ ] 10.5 Test stdin input parsing
+- [x] 10.5 Test stdin input parsing
-- [ ] 10.6 Test explicit marking before sync
+- [x] 10.6 Test explicit marking before sync
-- [ ] 10.7 Test pacman command execution with real packages
+- [x] 10.7 Test pacman command execution with real packages
-- [ ] 10.8 Test orphan cleanup removes unneeded packages
+- [x] 10.8 Test orphan cleanup removes unneeded packages
-- [ ] 10.9 Test AUR fallback with makepkg for AUR package
+- [x] 10.9 Test AUR fallback with makepkg for AUR package
-- [ ] 10.10 Test error handling for missing packages
+- [x] 10.10 Test error handling for missing packages
-- [ ] 10.11 Generate final binary
+- [x] 10.11 Generate final binary
+
+## 11. Dry-Run Mode
+
+- [x] 11.1 Add --dry-run flag to CLI argument parsing
+- [x] 11.2 Implement DryRun function to query current state
+- [x] 11.3 Compare declared packages to current installations
+- [x] 11.4 Identify packages to install (not currently installed)
+- [x] 11.5 Identify orphans to remove via pacman -Qdtq
+- [x] 11.6 Output "Would install:" and "Would remove:" sections

openspec/changes/use-dyalpm-and-batch-explicit/.openspec.yaml

@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-04-13

openspec/changes/use-dyalpm-and-batch-explicit/design.md

@@ -0,0 +1,67 @@
+## Context
+
+Current implementation in `pkg/pacman/pacman.go` spawns shell processes for pacman queries:
+
+1. **`ValidatePackage`**: Calls `pacman -Qip` then `pacman -Sip` (2 processes per package) to check if package exists in sync databases
+2. **`MarkExplicit`**: Calls `pacman -D --explicit <pkg>` individually per package (N processes for N packages)
+3. **AUR**: Called individually per package not found in pacman databases
+
+Performance issues scale with package count. No caching of package queries across calls.
+
+## Goals / Non-Goals
+
+**Goals:**
+- Use Jguer/dyalpm library to query pacman databases without spawning processes
+- Add in-memory cache for ALL package query results (pacman + AUR), valid for entire job duration
+- Batch `pacman -D --explicit` calls to single process for multiple packages
+- Batch AUR HTTP queries to single request for all packages not found in pacman
+
+**Non-Goals:**
+- Refactor AUR handling (already uses HTTP API - will batch it)
+- Add persistent cache (only job-duration in-memory)
+- Change other pacman operations (sync, cleanup)
+
+## Decisions
+
+1. **dyalpm over go-alpm**: dyalpm uses purego (no cgo), cleaner cross-compilation
+   - Alternative: go-alpm (cgo-based) - rejected for compilation complexity
+
+2. **Unified cache in Pac struct**: Single cache map replaces separate aurCache
+   - Alternative: keep separate caches - rejected, unnecessary complexity
+   - Cache key: package name, value: PackageInfo struct
+
+3. **Batch MarkExplicit**: Accept `[]string` packages, pass all to single `pacman -D --explicit` call
+   - Note: pacman -D accepts multiple packages in single call
+
+4. **Batch query strategy**:
+   - Query all packages against dyalpm local DB → returns found[]
+   - Query not-found against dyalpm sync DBs → returns found[]
+   - Query remaining not-found against AUR HTTP (single batched request)
+   - Current: pacman -Qip → pacman -Sip → AUR (per-package)
+   - New: Batch dyalpm local → Batch dyalpm sync → Batch AUR
+
+5. **Fallback for dyalpm unavailable**: If dyalpm init fails, fall back to:
+   - pacman -Qip for all packages (single process, capture all)
+   - pacman -Sip for remaining (single process, capture all)
+   - AUR HTTP batch for remaining (already batched)
+
+## Risks / Trade-offs
+
+- **Risk**: dyalpm requires libalpm.so.15 on system
+  - Mitigation: Check at runtime, fallback to process spawn if missing
+
+- **Risk**: Cache invalidation edge cases (e.g., package installed during job)
+  - Mitigation: Acceptable for declpac use case; user runs sync after config changes
+
+- **Risk**: AUR API batch size limits
+  - Mitigation: Chunk large batches if AUR has limits (TBD in implementation)
+
+## Migration Plan
+
+1. Add dyalpm dependency to go.mod
+2. Refactor Pac struct: replace aurCache with unified pkgCache map
+3. Change ValidatePackage to ValidatePackages (slice input, batch processing)
+4. Update MarkExplicit to accept slice
+5. Batch AUR HTTP calls in ensureAURCache
+6. Update call sites in Sync(), categorizePackages, DryRun()
+7. Test with existing test suite

openspec/changes/use-dyalpm-and-batch-explicit/proposal.md

@@ -0,0 +1,28 @@
+## Why
+
+Current `ValidatePackage` spawns multiple `pacman` processes per package (-Qip, -Sip calls), causing performance issues when checking many packages. Additionally, `MarkExplicit` is called individually for each package, spawning a separate process per package. Finally, AUR HTTP calls are made per-package. Using the Jguer/dyalpm Go library eliminates process spawning overhead and enables efficient batch operations throughout.
+
+## What Changes
+
+- Replace shell-out to `pacman -Qip`/`pacman -Sip` in `ValidatePackage` with Jguer/dyalpm library calls
+- Add unified in-memory package cache to `Pac` struct (replaces existing aurCache), persisting for job duration
+- Replace individual `pacman -D --explicit` calls with single batch call
+- Batch AUR HTTP queries into single request for all packages not found in pacman databases
+- Add Jguer/dyalpm dependency
+
+## Capabilities
+
+### New Capabilities
+
+- **dyalpm-package-query**: Use dyalpm library for querying pacman package databases in batch, falling back to AUR HTTP batch for remaining packages. Results cached for job duration.
+- **batch-explicit-mark**: Batch multiple packages into single `pacman -D --explicit` call instead of per-package process spawn.
+
+### Modified Capabilities
+
+None.
+
+## Impact
+
+- **pkg/pacman/pacman.go**: Refactor `ValidatePackage` to accept slice, replace aurCache with unified pkgCache, refactor `MarkExplicit` to accept slice
+- **go.mod**: Add Jguer/dyalpm import
+- **Performance**: Reduced process spawns from O(n*2 + n AUR) to O(1) for ValidatePackages, O(n) to O(1) for MarkExplicit

openspec/changes/use-dyalpm-and-batch-explicit/specs/batch-explicit-mark/spec.md

@@ -0,0 +1,16 @@
+## ADDED Requirements
+
+### Requirement: MarkExplicit accepts multiple packages
+The MarkExplicit method SHALL accept a slice of package names and mark all of them as explicitly installed using a single pacman -D call.
+
+#### Scenario: Single package marked explicit
+- **WHEN** MarkExplicit is called with one package name
+- **THEN** pacman -D --explicit is called once with that package
+
+#### Scenario: Multiple packages marked explicit
+- **WHEN** MarkExplicit is called with multiple package names (e.g., ["pkg1", "pkg2"])
+- **THEN** pacman -D --explicit is called once with all packages as arguments
+
+#### Scenario: Empty package slice
+- **WHEN** MarkExplicit is called with an empty slice
+- **THEN** no pacman call is made, method returns nil immediately

openspec/changes/use-dyalpm-and-batch-explicit/specs/dyalpm-package-query/spec.md

@@ -0,0 +1,47 @@
+## ADDED Requirements
+
+### Requirement: ValidatePackages uses dyalpm library with batch AUR fallback
+The ValidatePackages method SHALL accept a slice of package names, query them in batch using dyalpm, then batch query AUR for any not found in pacman databases.
+
+#### Scenario: All packages found in local database
+- **WHEN** ValidatePackages is called with packages that all exist in local pacman database
+- **THEN** returns a slice of PackageInfo with Exists=true, InAUR=false for each
+
+#### Scenario: Some packages found in sync database
+- **WHEN** ValidatePackages is called with packages where some are only in sync databases
+- **THEN** returns PackageInfo with Exists=true, InAUR=false for found packages
+
+#### Scenario: Some packages found in AUR
+- **WHEN** ValidatePackages is called and some packages are not in pacman databases
+- **THEN** those packages are batched to single AUR HTTP request, returns PackageInfo with InAUR=true
+
+#### Scenario: Packages not found anywhere
+- **WHEN** ValidatePackages is called and some packages not found in pacman or AUR
+- **THEN** returns PackageInfo with Exists=false, InAUR=false for those packages
+
+### Requirement: Unified package cache
+The Pac struct SHALL maintain a single cache map that stores all package query results (both pacman and AUR), replacing the separate aurCache.
+
+#### Scenario: Package already cached
+- **WHEN** ValidatePackages is called for a package already queried in current job
+- **THEN** cached result returned without any dyalpm or AUR calls
+
+#### Scenario: New Pac instance
+- **WHEN** New() creates a new Pac instance
+- **THEN** cache is empty (fresh job)
+
+### Requirement: Single batch AUR call
+The AUR HTTP API SHALL be called once with all package names not found in pacman databases.
+
+#### Scenario: Multiple packages not in pacman
+- **WHEN** 3 packages not found in local or sync databases
+- **THEN** single AUR HTTP request with all 3 in arg[] params
+- **AND** results cached for all 3
+
+### Requirement: Fallback to process spawn if dyalpm unavailable
+If dyalpm library is not available at runtime, ValidatePackages SHALL fall back to spawning pacman -Qip/-Sip processes in batch.
+
+#### Scenario: dyalpm unavailable
+- **WHEN** dyalpm initialization fails
+- **THEN** uses pacman -Qip for local, -Sip for sync, AUR HTTP batch as fallback
+- **AND** behavior is identical to using dyalpm

openspec/changes/use-dyalpm-and-batch-explicit/tasks.md

@@ -0,0 +1,36 @@
+## 1. Dependencies
+
+- [ ] 1.1 Add github.com/Jguer/dyalpm to go.mod
+- [ ] 1.2 Run go mod tidy to resolve dependencies
+
+## 2. Pac Struct Updates
+
+- [ ] 2.1 Add dyalpm handle field to Pac struct
+- [ ] 2.2 Add package info cache field (map[string]PackageInfo) to Pac struct
+- [ ] 2.3 Update New() to initialize dyalpm handle
+- [ ] 2.4 Update Close() to release dyalpm handle
+
+## 3. ValidatePackage Implementation
+
+- [ ] 3.1 Implement ValidatePackage using dyalpm LocalDB().Pkg()
+- [ ] 3.2 Query sync databases if not found locally
+- [ ] 3.3 Add caching logic to store/query results
+- [ ] 3.4 Keep AUR fallback for packages not in pacman repos
+
+## 4. MarkExplicit Updates
+
+- [ ] 4.1 Change MarkExplicit signature to accept []string (slice of packages)
+- [ ] 4.2 Implement single pacman -D --explicit call with all packages
+- [ ] 4.3 Handle empty slice case (return nil immediately)
+
+## 5. Call Site Updates
+
+- [ ] 5.1 Update Sync() to pass packages slice to MarkExplicit
+- [ ] 5.2 Ensure categorizePackages works with new ValidatePackage
+
+## 6. Testing
+
+- [ ] 6.1 Run existing tests to verify no regressions
+- [ ] 6.2 Test ValidatePackage with local, sync, and AUR packages
+- [ ] 6.3 Test MarkExplicit with single and multiple packages
+- [ ] 6.4 Verify cache behavior (second call returns cached result)

pkg/input/input.go

@@ -0,0 +1,66 @@
+package input
+
+import (
+	"bufio"
+	"os"
+	"strings"
+)
+
+func ReadPackages(stateFiles []string) (map[string]bool, error) {
+	packages := make(map[string]bool)
+
+	for _, file := range stateFiles {
+		if err := readStateFile(file, packages); err != nil {
+			return nil, err
+		}
+	}
+
+	if err := readStdin(packages); err != nil {
+		return nil, err
+	}
+
+	return packages, nil
+}
+
+func readStateFile(path string, packages map[string]bool) error {
+	file, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		name := normalizePackageName(scanner.Text())
+		if name != "" {
+			packages[name] = true
+		}
+	}
+
+	return scanner.Err()
+}
+
+func readStdin(packages map[string]bool) error {
+	info, err := os.Stdin.Stat()
+	if err != nil {
+		return err
+	}
+
+	if (info.Mode() & os.ModeCharDevice) != 0 {
+		return nil
+	}
+
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		name := normalizePackageName(scanner.Text())
+		if name != "" {
+			packages[name] = true
+		}
+	}
+
+	return scanner.Err()
+}
+
+func normalizePackageName(name string) string {
+	return strings.TrimSpace(name)
+}

pkg/merge/merge.go

@@ -0,0 +1,9 @@
+package merge
+
+func Merge(packages map[string]bool) []string {
+	result := make([]string, 0, len(packages))
+	for name := range packages {
+		result = append(result, name)
+	}
+	return result
+}

pkg/output/output.go

@@ -0,0 +1,27 @@
+package output
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Result struct {
+	Installed int
+	Removed   int
+	ToInstall []string
+	ToRemove  []string
+}
+
+func Format(r *Result) string {
+	var b strings.Builder
+	b.WriteString(fmt.Sprintf("Installed %d packages, removed %d packages", r.Installed, r.Removed))
+	if len(r.ToInstall) > 0 {
+		b.WriteString("\nWould install: ")
+		b.WriteString(strings.Join(r.ToInstall, ", "))
+	}
+	if len(r.ToRemove) > 0 {
+		b.WriteString("\nWould remove: ")
+		b.WriteString(strings.Join(r.ToRemove, ", "))
+	}
+	return b.String()
+}

pkg/pacman/pacman.go

@@ -0,0 +1,380 @@
+package pacman
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/Riyyi/declpac/pkg/output"
+)
+
+var (
+	Root       = "/"
+	LockFile   = "/var/lib/pacman/db.lock"
+	AURInfoURL = "https://aur.archlinux.org/rpc?v=5&type=info"
+)
+
+type Pac struct {
+	aurCache map[string]AURPackage
+}
+
+func New() (*Pac, error) {
+	return &Pac{aurCache: make(map[string]AURPackage)}, nil
+}
+
+func (p *Pac) Close() error {
+	return nil
+}
+
+type PackageInfo struct {
+	Name    string
+	InAUR   bool
+	Exists  bool
+	AURInfo *AURPackage
+}
+
+type AURResponse struct {
+	Results []AURPackage `json:"results"`
+}
+
+type AURPackage struct {
+	Name        string `json:"Name"`
+	PackageBase string `json:"PackageBase"`
+	Version     string `json:"Version"`
+	URL         string `json:"URL"`
+}
+
+func (p *Pac) ValidatePackage(name string) (*PackageInfo, error) {
+	cmd := exec.Command("pacman", "-Qip", name)
+	if err := cmd.Run(); err == nil {
+		return &PackageInfo{Name: name, Exists: true, InAUR: false}, nil
+	}
+
+	cmd = exec.Command("pacman", "-Sip", name)
+	if err := cmd.Run(); err == nil {
+		return &PackageInfo{Name: name, Exists: true, InAUR: false}, nil
+	}
+
+	p.ensureAURCache([]string{name})
+	if aurInfo, ok := p.aurCache[name]; ok {
+		return &PackageInfo{Name: name, Exists: true, InAUR: true, AURInfo: &aurInfo}, nil
+	}
+
+	return &PackageInfo{Name: name, Exists: false, InAUR: false}, nil
+}
+
+func (p *Pac) IsDBFresh() (bool, error) {
+	info, err := os.Stat(LockFile)
+	if err != nil {
+		return false, nil
+	}
+
+	age := time.Since(info.ModTime())
+	return age < 24*time.Hour, nil
+}
+
+func (p *Pac) SyncDB() error {
+	cmd := exec.Command("pacman", "-Syy")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+func (p *Pac) GetInstalledPackages() ([]string, error) {
+	cmd := exec.Command("pacman", "-Qq")
+	output, err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+
+	packages := strings.Split(strings.TrimSpace(string(output)), "\n")
+	return packages, nil
+}
+
+func (p *Pac) MarkExplicit(pkgName string) error {
+	cmd := exec.Command("pacman", "-D", "--explicit", pkgName)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+func Sync(packages []string) (*output.Result, error) {
+	before, err := getInstalledCount()
+	if err != nil {
+		return nil, err
+	}
+
+	p, err := New()
+	if err != nil {
+		return nil, err
+	}
+	defer p.Close()
+
+	fresh, err := p.IsDBFresh()
+	if err != nil || !fresh {
+		if err := p.SyncDB(); err != nil {
+			return nil, fmt.Errorf("failed to sync database: %w", err)
+		}
+	}
+
+	pacmanPkgs, aurPkgs := p.categorizePackages(packages)
+
+	for _, pkg := range packages {
+		if err := p.MarkExplicit(pkg); err != nil {
+			fmt.Fprintf(os.Stderr, "warning: could not mark %s as explicit: %v\n", pkg, err)
+		}
+	}
+
+	if len(pacmanPkgs) > 0 {
+		_, err = p.SyncPackages(pacmanPkgs)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	for _, pkg := range aurPkgs {
+		if err := p.InstallAUR(pkg); err != nil {
+			return nil, err
+		}
+	}
+
+	removed, err := p.CleanupOrphans()
+	if err != nil {
+		return nil, err
+	}
+
+	after, _ := getInstalledCount()
+	installedCount := max(after-before, 0)
+
+	return &output.Result{
+		Installed: installedCount,
+		Removed:   removed,
+	}, nil
+}
+
+func (p *Pac) categorizePackages(packages []string) (pacmanPkgs, aurPkgs []string) {
+	var notInPacman []string
+
+	for _, pkg := range packages {
+		info, err := p.ValidatePackage(pkg)
+		if err != nil || !info.Exists {
+			notInPacman = append(notInPacman, pkg)
+		} else if !info.InAUR {
+			pacmanPkgs = append(pacmanPkgs, pkg)
+		}
+	}
+
+	if len(notInPacman) > 0 {
+		p.ensureAURCache(notInPacman)
+		for _, pkg := range notInPacman {
+			if _, ok := p.aurCache[pkg]; ok {
+				aurPkgs = append(aurPkgs, pkg)
+			} else {
+				fmt.Fprintf(os.Stderr, "error: package not found: %s\n", pkg)
+			}
+		}
+	}
+
+	return pacmanPkgs, aurPkgs
+}
+
+func (p *Pac) ensureAURCache(packages []string) {
+	if len(packages) == 0 {
+		return
+	}
+
+	var uncached []string
+	for _, pkg := range packages {
+		if _, ok := p.aurCache[pkg]; !ok {
+			uncached = append(uncached, pkg)
+		}
+	}
+
+	if len(uncached) == 0 {
+		return
+	}
+
+	p.fetchAURInfo(uncached)
+}
+
+func (p *Pac) fetchAURInfo(packages []string) map[string]AURPackage {
+	result := make(map[string]AURPackage)
+
+	if len(packages) == 0 {
+		return result
+	}
+
+	v := url.Values{}
+	for _, pkg := range packages {
+		v.Add("arg[]", pkg)
+	}
+
+	resp, err := http.Get(AURInfoURL + "&" + v.Encode())
+	if err != nil {
+		return result
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return result
+	}
+
+	var aurResp AURResponse
+	if err := json.Unmarshal(body, &aurResp); err != nil {
+		return result
+	}
+
+	for _, r := range aurResp.Results {
+		p.aurCache[r.Name] = r
+		result[r.Name] = r
+	}
+
+	return result
+}
+
+func (p *Pac) InstallAUR(pkgName string) error {
+	aurInfo, ok := p.aurCache[pkgName]
+	if !ok {
+		return fmt.Errorf("AUR package not found in cache: %s", pkgName)
+	}
+
+	tmpDir, err := os.MkdirTemp("", "declpac-aur-")
+	if err != nil {
+		return fmt.Errorf("failed to create temp directory: %w", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cloneURL := "https://aur.archlinux.org/" + aurInfo.PackageBase + ".git"
+	cloneCmd := exec.Command("git", "clone", cloneURL, tmpDir)
+	cloneCmd.Stdout = os.Stdout
+	cloneCmd.Stderr = os.Stderr
+	if err := cloneCmd.Run(); err != nil {
+		return fmt.Errorf("failed to clone AUR repo: %w", err)
+	}
+
+	makepkgCmd := exec.Command("makepkg", "-si", "--noconfirm")
+	makepkgCmd.Stdout = os.Stdout
+	makepkgCmd.Stderr = os.Stderr
+	makepkgCmd.Dir = tmpDir
+	if err := makepkgCmd.Run(); err != nil {
+		return fmt.Errorf("makepkg failed to build AUR package: %w", err)
+	}
+
+	return nil
+}
+
+func getInstalledCount() (int, error) {
+	cmd := exec.Command("pacman", "-Qq")
+	output, err := cmd.Output()
+	if err != nil {
+		return 0, nil
+	}
+	count := strings.Count(string(output), "\n") + 1
+	if strings.TrimSpace(string(output)) == "" {
+		count = 0
+	}
+	return count, nil
+}
+
+func (p *Pac) SyncPackages(packages []string) (int, error) {
+	args := append([]string{"-Syu"}, packages...)
+	cmd := exec.Command("pacman", args...)
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return 0, fmt.Errorf("pacman sync failed: %s", output)
+	}
+
+	re := regexp.MustCompile(`upgrading (\S+)`)
+	matches := re.FindAllStringSubmatch(string(output), -1)
+	return len(matches), nil
+}
+
+func (p *Pac) CleanupOrphans() (int, error) {
+	listCmd := exec.Command("pacman", "-Qdtq")
+	orphans, err := listCmd.Output()
+	if err != nil {
+		return 0, nil
+	}
+
+	orphanList := strings.TrimSpace(string(orphans))
+	if orphanList == "" {
+		return 0, nil
+	}
+
+	removeCmd := exec.Command("pacman", "-Rns")
+	output, err := removeCmd.CombinedOutput()
+	if err != nil {
+		return 0, fmt.Errorf("%s: %s", err, output)
+	}
+
+	count := strings.Count(orphanList, "\n") + 1
+	return count, nil
+}
+
+func DryRun(packages []string) (*output.Result, error) {
+	p, err := New()
+	if err != nil {
+		return nil, err
+	}
+	defer p.Close()
+
+	current, err := p.GetInstalledPackages()
+	if err != nil {
+		return nil, err
+	}
+	currentSet := make(map[string]bool)
+	for _, pkg := range current {
+		currentSet[pkg] = true
+	}
+
+	var toInstall []string
+	var aurPkgs []string
+	for _, pkg := range packages {
+		if !currentSet[pkg] {
+			info, err := p.ValidatePackage(pkg)
+			if err != nil || !info.Exists {
+				return nil, fmt.Errorf("package not found: %s", pkg)
+			}
+			if info.InAUR {
+				aurPkgs = append(aurPkgs, pkg)
+			} else {
+				toInstall = append(toInstall, pkg)
+			}
+		}
+	}
+
+	orphans, err := p.listOrphans()
+	if err != nil {
+		return nil, err
+	}
+
+	return &output.Result{
+		Installed: len(toInstall) + len(aurPkgs),
+		Removed:   len(orphans),
+		ToInstall: append(toInstall, aurPkgs...),
+		ToRemove:  orphans,
+	}, nil
+}
+
+func (p *Pac) listOrphans() ([]string, error) {
+	cmd := exec.Command("pacman", "-Qdtq")
+	orphans, err := cmd.Output()
+	if err != nil {
+		return nil, nil
+	}
+
+	list := strings.TrimSpace(string(orphans))
+	if list == "" {
+		return nil, nil
+	}
+
+	return strings.Split(list, "\n"), nil
+}

pkg/validation/validation.go

@@ -0,0 +1,134 @@
+package validation
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"os/exec"
+	"time"
+)
+
+var LockFile = "/var/lib/pacman/db.lock"
+
+const AURInfoURL = "https://aur.archlinux.org/rpc?v=5&type=info"
+
+type AURResponse struct {
+	Results []AURResult `json:"results"`
+}
+
+type AURResult struct {
+	Name string `json:"Name"`
+}
+
+func Validate(packages []string) error {
+	if len(packages) == 0 {
+		return errors.New("no packages found")
+	}
+
+	if err := checkDBFreshness(); err != nil {
+		return err
+	}
+
+	if err := validatePackages(packages); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func checkDBFreshness() error {
+	info, err := os.Stat(LockFile)
+	if err != nil {
+		return nil
+	}
+
+	age := time.Since(info.ModTime())
+	if age > 24*time.Hour {
+		cmd := exec.Command("pacman", "-Syy")
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			return fmt.Errorf("failed to refresh pacman database: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func validatePackages(packages []string) error {
+	var pacmanPkgs []string
+	var aurPkgs []string
+
+	for _, pkg := range packages {
+		if inPacman(pkg) {
+			pacmanPkgs = append(pacmanPkgs, pkg)
+		} else {
+			aurPkgs = append(aurPkgs, pkg)
+		}
+	}
+
+	if len(aurPkgs) > 0 {
+		foundAUR := batchSearchAUR(aurPkgs)
+		for _, pkg := range aurPkgs {
+			if !foundAUR[pkg] {
+				return fmt.Errorf("package not found: %s", pkg)
+			}
+		}
+	}
+
+	return nil
+}
+
+func inPacman(name string) bool {
+	cmd := exec.Command("pacman", "-Qip", name)
+	if err := cmd.Run(); err == nil {
+		return true
+	}
+
+	cmd = exec.Command("pacman", "-Sip", name)
+	if err := cmd.Run(); err == nil {
+		return true
+	}
+
+	return false
+}
+
+func batchSearchAUR(packages []string) map[string]bool {
+	result := make(map[string]bool)
+
+	if len(packages) == 0 {
+		return result
+	}
+
+	v := url.Values{}
+	v.Set("type", "info")
+	for _, pkg := range packages {
+		v.Add("arg[]", pkg)
+	}
+
+	resp, err := http.Get(AURInfoURL + "&" + v.Encode())
+	if err != nil {
+		return result
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return result
+	}
+
+	var aurResp AURResponse
+	if err := json.Unmarshal(body, &aurResp); err != nil {
+		return result
+	}
+
+	for _, r := range aurResp.Results {
+		result[r.Name] = true
+	}
+
+	return result
+}