feat: initial commit — unarr CLI

Search, inspect, stream, and download torrents from the terminal.
Replaces the entire *arr stack with a single binary.

internal/engine/verify.go

@@ -0,0 +1,59 @@
+package engine
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// verify checks that a downloaded file or directory is valid.
+func verify(result *Result) error {
+	if result == nil || result.FilePath == "" {
+		return fmt.Errorf("no file path in result")
+	}
+
+	fi, err := os.Stat(result.FilePath)
+	if err != nil {
+		return fmt.Errorf("file not found: %w", err)
+	}
+
+	// Get actual size — handle both files and directories (multi-file torrents)
+	var actualSize int64
+	if fi.IsDir() {
+		actualSize, err = dirSize(result.FilePath)
+		if err != nil {
+			return fmt.Errorf("could not calculate dir size: %w", err)
+		}
+	} else {
+		actualSize = fi.Size()
+	}
+
+	if actualSize == 0 {
+		return fmt.Errorf("download is empty: %s", result.FilePath)
+	}
+
+	// If we know the expected size, check within 2% tolerance
+	if result.Size > 0 {
+		tolerance := int64(float64(result.Size) * 0.02)
+		if actualSize < result.Size-tolerance {
+			return fmt.Errorf("size mismatch: expected %d, got %d", result.Size, actualSize)
+		}
+	}
+
+	return nil
+}
+
+// dirSize returns total size of all files in a directory.
+func dirSize(path string) (int64, error) {
+	var total int64
+	err := filepath.Walk(path, func(_ string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !fi.IsDir() {
+			total += fi.Size()
+		}
+		return nil
+	})
+	return total, err
+}