internal/blobgen/compress_test.go

@@ -0,0 +1,64 @@
+package blobgen
+
+import (
+	"bytes"
+	"crypto/rand"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// testRecipient is a static age recipient for tests.
+const testRecipient = "age1cplgrwj77ta54dnmydvvmzn64ltk83ankxl5sww04mrtmu62kv3s89gmvv"
+
+// TestCompressStreamNoDoubleClose is a regression test for issue #28.
+// It verifies that CompressStream does not panic or return an error due to
+// double-closing the underlying blobgen.Writer. Before the fix in PR #33,
+// the explicit Close() on the happy path combined with defer Close() would
+// cause a double close.
+func TestCompressStreamNoDoubleClose(t *testing.T) {
+	input := []byte("regression test data for issue #28 double-close fix")
+	var buf bytes.Buffer
+
+	written, hash, err := CompressStream(&buf, bytes.NewReader(input), 3, []string{testRecipient})
+	require.NoError(t, err, "CompressStream should not return an error")
+	assert.True(t, written > 0, "expected bytes written > 0")
+	assert.NotEmpty(t, hash, "expected non-empty hash")
+	assert.True(t, buf.Len() > 0, "expected non-empty output")
+}
+
+// TestCompressStreamLargeInput exercises CompressStream with a larger payload
+// to ensure no double-close issues surface under heavier I/O.
+func TestCompressStreamLargeInput(t *testing.T) {
+	data := make([]byte, 512*1024) // 512 KB
+	_, err := rand.Read(data)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	written, hash, err := CompressStream(&buf, bytes.NewReader(data), 3, []string{testRecipient})
+	require.NoError(t, err)
+	assert.True(t, written > 0)
+	assert.NotEmpty(t, hash)
+}
+
+// TestCompressStreamEmptyInput verifies CompressStream handles empty input
+// without double-close issues.
+func TestCompressStreamEmptyInput(t *testing.T) {
+	var buf bytes.Buffer
+	_, hash, err := CompressStream(&buf, strings.NewReader(""), 3, []string{testRecipient})
+	require.NoError(t, err)
+	assert.NotEmpty(t, hash)
+}
+
+// TestCompressDataNoDoubleClose mirrors the stream test for CompressData,
+// ensuring the explicit Close + error-path Close pattern is also safe.
+func TestCompressDataNoDoubleClose(t *testing.T) {
+	input := []byte("CompressData regression test for double-close")
+	result, err := CompressData(input, 3, []string{testRecipient})
+	require.NoError(t, err)
+	assert.True(t, result.CompressedSize > 0)
+	assert.True(t, result.UncompressedSize == int64(len(input)))
+	assert.NotEmpty(t, result.SHA256)
+}

internal/vaultik/blob_fetch_stub.go

@@ -0,0 +1,55 @@
+package vaultik
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"filippo.io/age"
+	"git.eeqj.de/sneak/vaultik/internal/blobgen"
+)
+
+// FetchAndDecryptBlobResult holds the result of fetching and decrypting a blob.
+type FetchAndDecryptBlobResult struct {
+	Data []byte
+}
+
+// FetchAndDecryptBlob downloads a blob, decrypts it, and returns the plaintext data.
+func (v *Vaultik) FetchAndDecryptBlob(ctx context.Context, blobHash string, expectedSize int64, identity age.Identity) (*FetchAndDecryptBlobResult, error) {
+	rc, _, err := v.FetchBlob(ctx, blobHash, expectedSize)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rc.Close() }()
+
+	reader, err := blobgen.NewReader(rc, identity)
+	if err != nil {
+		return nil, fmt.Errorf("creating blob reader: %w", err)
+	}
+	defer func() { _ = reader.Close() }()
+
+	data, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, fmt.Errorf("reading blob data: %w", err)
+	}
+
+	return &FetchAndDecryptBlobResult{Data: data}, nil
+}
+
+// FetchBlob downloads a blob and returns a reader for the encrypted data.
+func (v *Vaultik) FetchBlob(ctx context.Context, blobHash string, expectedSize int64) (io.ReadCloser, int64, error) {
+	blobPath := fmt.Sprintf("blobs/%s/%s/%s", blobHash[:2], blobHash[2:4], blobHash)
+
+	rc, err := v.Storage.Get(ctx, blobPath)
+	if err != nil {
+		return nil, 0, fmt.Errorf("downloading blob %s: %w", blobHash[:16], err)
+	}
+
+	info, err := v.Storage.Stat(ctx, blobPath)
+	if err != nil {
+		_ = rc.Close()
+		return nil, 0, fmt.Errorf("stat blob %s: %w", blobHash[:16], err)
+	}
+
+	return rc, info.Size, nil
+}

internal/vaultik/blobcache.go

@@ -0,0 +1,207 @@
+package vaultik
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// blobDiskCacheEntry tracks a cached blob on disk.
+type blobDiskCacheEntry struct {
+	key  string
+	size int64
+	prev *blobDiskCacheEntry
+	next *blobDiskCacheEntry
+}
+
+// blobDiskCache is an LRU cache that stores blobs on disk instead of in memory.
+// Blobs are written to a temp directory keyed by their hash. When total size
+// exceeds maxBytes, the least-recently-used entries are evicted (deleted from disk).
+type blobDiskCache struct {
+	mu       sync.Mutex
+	dir      string
+	maxBytes int64
+	curBytes int64
+	items    map[string]*blobDiskCacheEntry
+	head     *blobDiskCacheEntry // most recent
+	tail     *blobDiskCacheEntry // least recent
+}
+
+// newBlobDiskCache creates a new disk-based blob cache with the given max size.
+func newBlobDiskCache(maxBytes int64) (*blobDiskCache, error) {
+	dir, err := os.MkdirTemp("", "vaultik-blobcache-*")
+	if err != nil {
+		return nil, fmt.Errorf("creating blob cache dir: %w", err)
+	}
+	return &blobDiskCache{
+		dir:      dir,
+		maxBytes: maxBytes,
+		items:    make(map[string]*blobDiskCacheEntry),
+	}, nil
+}
+
+func (c *blobDiskCache) path(key string) string {
+	return filepath.Join(c.dir, key)
+}
+
+func (c *blobDiskCache) unlink(e *blobDiskCacheEntry) {
+	if e.prev != nil {
+		e.prev.next = e.next
+	} else {
+		c.head = e.next
+	}
+	if e.next != nil {
+		e.next.prev = e.prev
+	} else {
+		c.tail = e.prev
+	}
+	e.prev = nil
+	e.next = nil
+}
+
+func (c *blobDiskCache) pushFront(e *blobDiskCacheEntry) {
+	e.prev = nil
+	e.next = c.head
+	if c.head != nil {
+		c.head.prev = e
+	}
+	c.head = e
+	if c.tail == nil {
+		c.tail = e
+	}
+}
+
+func (c *blobDiskCache) evictLRU() {
+	if c.tail == nil {
+		return
+	}
+	victim := c.tail
+	c.unlink(victim)
+	delete(c.items, victim.key)
+	c.curBytes -= victim.size
+	_ = os.Remove(c.path(victim.key))
+}
+
+// Put writes blob data to disk cache. Entries larger than maxBytes are silently skipped.
+func (c *blobDiskCache) Put(key string, data []byte) error {
+	entrySize := int64(len(data))
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if entrySize > c.maxBytes {
+		return nil
+	}
+
+	// Remove old entry if updating
+	if e, ok := c.items[key]; ok {
+		c.unlink(e)
+		c.curBytes -= e.size
+		_ = os.Remove(c.path(key))
+		delete(c.items, key)
+	}
+
+	if err := os.WriteFile(c.path(key), data, 0600); err != nil {
+		return fmt.Errorf("writing blob to cache: %w", err)
+	}
+
+	e := &blobDiskCacheEntry{key: key, size: entrySize}
+	c.pushFront(e)
+	c.items[key] = e
+	c.curBytes += entrySize
+
+	for c.curBytes > c.maxBytes && c.tail != nil {
+		c.evictLRU()
+	}
+
+	return nil
+}
+
+// Get reads a cached blob from disk. Returns data and true on hit.
+func (c *blobDiskCache) Get(key string) ([]byte, bool) {
+	c.mu.Lock()
+	e, ok := c.items[key]
+	if !ok {
+		c.mu.Unlock()
+		return nil, false
+	}
+	c.unlink(e)
+	c.pushFront(e)
+	c.mu.Unlock()
+
+	data, err := os.ReadFile(c.path(key))
+	if err != nil {
+		c.mu.Lock()
+		if e2, ok2 := c.items[key]; ok2 && e2 == e {
+			c.unlink(e)
+			delete(c.items, key)
+			c.curBytes -= e.size
+		}
+		c.mu.Unlock()
+		return nil, false
+	}
+	return data, true
+}
+
+// ReadAt reads a slice of a cached blob without loading the entire blob into memory.
+func (c *blobDiskCache) ReadAt(key string, offset, length int64) ([]byte, error) {
+	c.mu.Lock()
+	e, ok := c.items[key]
+	if !ok {
+		c.mu.Unlock()
+		return nil, fmt.Errorf("key %q not in cache", key)
+	}
+	if offset+length > e.size {
+		c.mu.Unlock()
+		return nil, fmt.Errorf("read beyond blob size: offset=%d length=%d size=%d", offset, length, e.size)
+	}
+	c.unlink(e)
+	c.pushFront(e)
+	c.mu.Unlock()
+
+	f, err := os.Open(c.path(key))
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = f.Close() }()
+
+	buf := make([]byte, length)
+	if _, err := f.ReadAt(buf, offset); err != nil {
+		return nil, err
+	}
+	return buf, nil
+}
+
+// Has returns whether a key exists in the cache.
+func (c *blobDiskCache) Has(key string) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	_, ok := c.items[key]
+	return ok
+}
+
+// Size returns current total cached bytes.
+func (c *blobDiskCache) Size() int64 {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.curBytes
+}
+
+// Len returns number of cached entries.
+func (c *blobDiskCache) Len() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return len(c.items)
+}
+
+// Close removes the cache directory and all cached blobs.
+func (c *blobDiskCache) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.items = nil
+	c.head = nil
+	c.tail = nil
+	c.curBytes = 0
+	return os.RemoveAll(c.dir)
+}

internal/vaultik/blobcache_test.go

@@ -0,0 +1,189 @@
+package vaultik
+
+import (
+	"bytes"
+	"crypto/rand"
+	"fmt"
+	"testing"
+)
+
+func TestBlobDiskCache_BasicGetPut(t *testing.T) {
+	cache, err := newBlobDiskCache(1 << 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = cache.Close() }()
+
+	data := []byte("hello world")
+	if err := cache.Put("key1", data); err != nil {
+		t.Fatal(err)
+	}
+
+	got, ok := cache.Get("key1")
+	if !ok {
+		t.Fatal("expected cache hit")
+	}
+	if !bytes.Equal(got, data) {
+		t.Fatalf("got %q, want %q", got, data)
+	}
+
+	_, ok = cache.Get("nonexistent")
+	if ok {
+		t.Fatal("expected cache miss")
+	}
+}
+
+func TestBlobDiskCache_EvictionUnderPressure(t *testing.T) {
+	maxBytes := int64(1000)
+	cache, err := newBlobDiskCache(maxBytes)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = cache.Close() }()
+
+	for i := 0; i < 5; i++ {
+		data := make([]byte, 300)
+		if err := cache.Put(fmt.Sprintf("key%d", i), data); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if cache.Size() > maxBytes {
+		t.Fatalf("cache size %d exceeds max %d", cache.Size(), maxBytes)
+	}
+
+	if !cache.Has("key4") {
+		t.Fatal("expected key4 to be cached")
+	}
+	if cache.Has("key0") {
+		t.Fatal("expected key0 to be evicted")
+	}
+}
+
+func TestBlobDiskCache_OversizedEntryRejected(t *testing.T) {
+	cache, err := newBlobDiskCache(100)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = cache.Close() }()
+
+	data := make([]byte, 200)
+	if err := cache.Put("big", data); err != nil {
+		t.Fatal(err)
+	}
+
+	if cache.Has("big") {
+		t.Fatal("oversized entry should not be cached")
+	}
+}
+
+func TestBlobDiskCache_UpdateInPlace(t *testing.T) {
+	cache, err := newBlobDiskCache(1 << 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = cache.Close() }()
+
+	if err := cache.Put("key1", []byte("v1")); err != nil {
+		t.Fatal(err)
+	}
+	if err := cache.Put("key1", []byte("version2")); err != nil {
+		t.Fatal(err)
+	}
+
+	got, ok := cache.Get("key1")
+	if !ok {
+		t.Fatal("expected hit")
+	}
+	if string(got) != "version2" {
+		t.Fatalf("got %q, want %q", got, "version2")
+	}
+	if cache.Len() != 1 {
+		t.Fatalf("expected 1 entry, got %d", cache.Len())
+	}
+	if cache.Size() != int64(len("version2")) {
+		t.Fatalf("expected size %d, got %d", len("version2"), cache.Size())
+	}
+}
+
+func TestBlobDiskCache_ReadAt(t *testing.T) {
+	cache, err := newBlobDiskCache(1 << 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = cache.Close() }()
+
+	data := make([]byte, 1024)
+	if _, err := rand.Read(data); err != nil {
+		t.Fatal(err)
+	}
+	if err := cache.Put("blob1", data); err != nil {
+		t.Fatal(err)
+	}
+
+	chunk, err := cache.ReadAt("blob1", 100, 200)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(chunk, data[100:300]) {
+		t.Fatal("ReadAt returned wrong data")
+	}
+
+	_, err = cache.ReadAt("blob1", 900, 200)
+	if err == nil {
+		t.Fatal("expected error for out-of-bounds read")
+	}
+
+	_, err = cache.ReadAt("missing", 0, 10)
+	if err == nil {
+		t.Fatal("expected error for missing key")
+	}
+}
+
+func TestBlobDiskCache_Close(t *testing.T) {
+	cache, err := newBlobDiskCache(1 << 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := cache.Put("key1", []byte("data")); err != nil {
+		t.Fatal(err)
+	}
+	if err := cache.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestBlobDiskCache_LRUOrder(t *testing.T) {
+	cache, err := newBlobDiskCache(200)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = cache.Close() }()
+
+	d := make([]byte, 100)
+	if err := cache.Put("a", d); err != nil {
+		t.Fatal(err)
+	}
+	if err := cache.Put("b", d); err != nil {
+		t.Fatal(err)
+	}
+
+	// Access "a" to make it most recently used
+	cache.Get("a")
+
+	// Adding "c" should evict "b" (LRU), not "a"
+	if err := cache.Put("c", d); err != nil {
+		t.Fatal(err)
+	}
+
+	if !cache.Has("a") {
+		t.Fatal("expected 'a' to survive")
+	}
+	if !cache.Has("c") {
+		t.Fatal("expected 'c' to be present")
+	}
+	if cache.Has("b") {
+		t.Fatal("expected 'b' to be evicted")
+	}
+}

internal/vaultik/info.go

@@ -15,99 +15,99 @@ import (
 // ShowInfo displays system and configuration information
 func (v *Vaultik) ShowInfo() error {
 	// System Information
-	fmt.Printf("=== System Information ===\n")
-	fmt.Printf("OS/Architecture: %s/%s\n", runtime.GOOS, runtime.GOARCH)
-	fmt.Printf("Version:         %s\n", v.Globals.Version)
-	fmt.Printf("Commit:          %s\n", v.Globals.Commit)
-	fmt.Printf("Go Version:      %s\n", runtime.Version())
-	fmt.Println()
+	v.printfStdout("=== System Information ===\n")
+	v.printfStdout("OS/Architecture: %s/%s\n", runtime.GOOS, runtime.GOARCH)
+	v.printfStdout("Version:         %s\n", v.Globals.Version)
+	v.printfStdout("Commit:          %s\n", v.Globals.Commit)
+	v.printfStdout("Go Version:      %s\n", runtime.Version())
+	v.printlnStdout()
 
 	// Storage Configuration
-	fmt.Printf("=== Storage Configuration ===\n")
-	fmt.Printf("S3 Bucket:       %s\n", v.Config.S3.Bucket)
+	v.printfStdout("=== Storage Configuration ===\n")
+	v.printfStdout("S3 Bucket:       %s\n", v.Config.S3.Bucket)
 	if v.Config.S3.Prefix != "" {
-		fmt.Printf("S3 Prefix:       %s\n", v.Config.S3.Prefix)
+		v.printfStdout("S3 Prefix:       %s\n", v.Config.S3.Prefix)
 	}
-	fmt.Printf("S3 Endpoint:     %s\n", v.Config.S3.Endpoint)
-	fmt.Printf("S3 Region:       %s\n", v.Config.S3.Region)
-	fmt.Println()
+	v.printfStdout("S3 Endpoint:     %s\n", v.Config.S3.Endpoint)
+	v.printfStdout("S3 Region:       %s\n", v.Config.S3.Region)
+	v.printlnStdout()
 
 	// Backup Settings
-	fmt.Printf("=== Backup Settings ===\n")
+	v.printfStdout("=== Backup Settings ===\n")
 
 	// Show configured snapshots
-	fmt.Printf("Snapshots:\n")
+	v.printfStdout("Snapshots:\n")
 	for _, name := range v.Config.SnapshotNames() {
 		snap := v.Config.Snapshots[name]
-		fmt.Printf("  %s:\n", name)
+		v.printfStdout("  %s:\n", name)
 		for _, path := range snap.Paths {
-			fmt.Printf("    - %s\n", path)
+			v.printfStdout("    - %s\n", path)
 		}
 		if len(snap.Exclude) > 0 {
-			fmt.Printf("    exclude: %s\n", strings.Join(snap.Exclude, ", "))
+			v.printfStdout("    exclude: %s\n", strings.Join(snap.Exclude, ", "))
 		}
 	}
 
 	// Global exclude patterns
 	if len(v.Config.Exclude) > 0 {
-		fmt.Printf("Global Exclude:  %s\n", strings.Join(v.Config.Exclude, ", "))
+		v.printfStdout("Global Exclude:  %s\n", strings.Join(v.Config.Exclude, ", "))
 	}
 
-	fmt.Printf("Compression:     zstd level %d\n", v.Config.CompressionLevel)
-	fmt.Printf("Chunk Size:      %s\n", humanize.Bytes(uint64(v.Config.ChunkSize)))
-	fmt.Printf("Blob Size Limit: %s\n", humanize.Bytes(uint64(v.Config.BlobSizeLimit)))
-	fmt.Println()
+	v.printfStdout("Compression:     zstd level %d\n", v.Config.CompressionLevel)
+	v.printfStdout("Chunk Size:      %s\n", humanize.Bytes(uint64(v.Config.ChunkSize)))
+	v.printfStdout("Blob Size Limit: %s\n", humanize.Bytes(uint64(v.Config.BlobSizeLimit)))
+	v.printlnStdout()
 
 	// Encryption Configuration
-	fmt.Printf("=== Encryption Configuration ===\n")
-	fmt.Printf("Recipients:\n")
+	v.printfStdout("=== Encryption Configuration ===\n")
+	v.printfStdout("Recipients:\n")
 	for _, recipient := range v.Config.AgeRecipients {
-		fmt.Printf("  - %s\n", recipient)
+		v.printfStdout("  - %s\n", recipient)
 	}
-	fmt.Println()
+	v.printlnStdout()
 
 	// Daemon Settings (if applicable)
 	if v.Config.BackupInterval > 0 || v.Config.MinTimeBetweenRun > 0 {
-		fmt.Printf("=== Daemon Settings ===\n")
+		v.printfStdout("=== Daemon Settings ===\n")
 		if v.Config.BackupInterval > 0 {
-			fmt.Printf("Backup Interval: %s\n", v.Config.BackupInterval)
+			v.printfStdout("Backup Interval: %s\n", v.Config.BackupInterval)
 		}
 		if v.Config.MinTimeBetweenRun > 0 {
-			fmt.Printf("Minimum Time:    %s\n", v.Config.MinTimeBetweenRun)
+			v.printfStdout("Minimum Time:    %s\n", v.Config.MinTimeBetweenRun)
 		}
-		fmt.Println()
+		v.printlnStdout()
 	}
 
 	// Local Database
-	fmt.Printf("=== Local Database ===\n")
-	fmt.Printf("Index Path:      %s\n", v.Config.IndexPath)
+	v.printfStdout("=== Local Database ===\n")
+	v.printfStdout("Index Path:      %s\n", v.Config.IndexPath)
 
 	// Check if index file exists and get its size
 	if info, err := v.Fs.Stat(v.Config.IndexPath); err == nil {
-		fmt.Printf("Index Size:      %s\n", humanize.Bytes(uint64(info.Size())))
+		v.printfStdout("Index Size:      %s\n", humanize.Bytes(uint64(info.Size())))
 
 		// Get snapshot count from database
 		query := `SELECT COUNT(*) FROM snapshots WHERE completed_at IS NOT NULL`
 		var snapshotCount int
 		if err := v.DB.Conn().QueryRowContext(v.ctx, query).Scan(&snapshotCount); err == nil {
-			fmt.Printf("Snapshots:       %d\n", snapshotCount)
+			v.printfStdout("Snapshots:       %d\n", snapshotCount)
 		}
 
 		// Get blob count from database
 		query = `SELECT COUNT(*) FROM blobs`
 		var blobCount int
 		if err := v.DB.Conn().QueryRowContext(v.ctx, query).Scan(&blobCount); err == nil {
-			fmt.Printf("Blobs:           %d\n", blobCount)
+			v.printfStdout("Blobs:           %d\n", blobCount)
 		}
 
 		// Get file count from database
 		query = `SELECT COUNT(*) FROM files`
 		var fileCount int
 		if err := v.DB.Conn().QueryRowContext(v.ctx, query).Scan(&fileCount); err == nil {
-			fmt.Printf("Files:           %d\n", fileCount)
+			v.printfStdout("Files:           %d\n", fileCount)
 		}
 	} else {
-		fmt.Printf("Index Size:      (not created)\n")
+		v.printfStdout("Index Size:      (not created)\n")
 	}
 
 	return nil
@@ -157,15 +157,15 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 	result.StorageLocation = storageInfo.Location
 
 	if !jsonOutput {
-		fmt.Printf("=== Remote Storage ===\n")
-		fmt.Printf("Type:     %s\n", storageInfo.Type)
-		fmt.Printf("Location: %s\n", storageInfo.Location)
-		fmt.Println()
+		v.printfStdout("=== Remote Storage ===\n")
+		v.printfStdout("Type:     %s\n", storageInfo.Type)
+		v.printfStdout("Location: %s\n", storageInfo.Location)
+		v.printlnStdout()
 	}
 
 	// List all snapshot metadata
 	if !jsonOutput {
-		fmt.Printf("Scanning snapshot metadata...\n")
+		v.printfStdout("Scanning snapshot metadata...\n")
 	}
 
 	snapshotMetadata := make(map[string]*SnapshotMetadataInfo)
@@ -210,7 +210,7 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 
 	// Download and parse all manifests to get referenced blobs
 	if !jsonOutput {
-		fmt.Printf("Downloading %d manifest(s)...\n", len(snapshotIDs))
+		v.printfStdout("Downloading %d manifest(s)...\n", len(snapshotIDs))
 	}
 
 	referencedBlobs := make(map[string]int64) // hash -> compressed size
@@ -260,7 +260,7 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 
 	// List all blobs on remote
 	if !jsonOutput {
-		fmt.Printf("Scanning blobs...\n")
+		v.printfStdout("Scanning blobs...\n")
 	}
 
 	allBlobs := make(map[string]int64) // hash -> size from storage
@@ -298,14 +298,14 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 	}
 
 	// Human-readable output
-	fmt.Printf("\n=== Snapshot Metadata ===\n")
+	v.printfStdout("\n=== Snapshot Metadata ===\n")
 	if len(result.Snapshots) == 0 {
-		fmt.Printf("No snapshots found\n")
+		v.printfStdout("No snapshots found\n")
 	} else {
-		fmt.Printf("%-45s %12s %12s %12s %10s %12s\n", "SNAPSHOT", "MANIFEST", "DATABASE", "TOTAL", "BLOBS", "BLOB SIZE")
-		fmt.Printf("%-45s %12s %12s %12s %10s %12s\n", strings.Repeat("-", 45), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 10), strings.Repeat("-", 12))
+		v.printfStdout("%-45s %12s %12s %12s %10s %12s\n", "SNAPSHOT", "MANIFEST", "DATABASE", "TOTAL", "BLOBS", "BLOB SIZE")
+		v.printfStdout("%-45s %12s %12s %12s %10s %12s\n", strings.Repeat("-", 45), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 10), strings.Repeat("-", 12))
 		for _, info := range result.Snapshots {
-			fmt.Printf("%-45s %12s %12s %12s %10s %12s\n",
+			v.printfStdout("%-45s %12s %12s %12s %10s %12s\n",
 				truncateString(info.SnapshotID, 45),
 				humanize.Bytes(uint64(info.ManifestSize)),
 				humanize.Bytes(uint64(info.DatabaseSize)),
@@ -314,23 +314,23 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 				humanize.Bytes(uint64(info.BlobsSize)),
 			)
 		}
-		fmt.Printf("%-45s %12s %12s %12s %10s %12s\n", strings.Repeat("-", 45), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 10), strings.Repeat("-", 12))
-		fmt.Printf("%-45s %12s %12s %12s\n", fmt.Sprintf("Total (%d snapshots)", result.TotalMetadataCount), "", "", humanize.Bytes(uint64(result.TotalMetadataSize)))
+		v.printfStdout("%-45s %12s %12s %12s %10s %12s\n", strings.Repeat("-", 45), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 12), strings.Repeat("-", 10), strings.Repeat("-", 12))
+		v.printfStdout("%-45s %12s %12s %12s\n", fmt.Sprintf("Total (%d snapshots)", result.TotalMetadataCount), "", "", humanize.Bytes(uint64(result.TotalMetadataSize)))
 	}
 
-	fmt.Printf("\n=== Blob Storage ===\n")
-	fmt.Printf("Total blobs on remote:      %s (%s)\n",
+	v.printfStdout("\n=== Blob Storage ===\n")
+	v.printfStdout("Total blobs on remote:      %s (%s)\n",
 		humanize.Comma(int64(result.TotalBlobCount)),
 		humanize.Bytes(uint64(result.TotalBlobSize)))
-	fmt.Printf("Referenced by snapshots:    %s (%s)\n",
+	v.printfStdout("Referenced by snapshots:    %s (%s)\n",
 		humanize.Comma(int64(result.ReferencedBlobCount)),
 		humanize.Bytes(uint64(result.ReferencedBlobSize)))
-	fmt.Printf("Orphaned (unreferenced):    %s (%s)\n",
+	v.printfStdout("Orphaned (unreferenced):    %s (%s)\n",
 		humanize.Comma(int64(result.OrphanedBlobCount)),
 		humanize.Bytes(uint64(result.OrphanedBlobSize)))
 
 	if result.OrphanedBlobCount > 0 {
-		fmt.Printf("\nRun 'vaultik prune --remote' to remove orphaned blobs.\n")
+		v.printfStdout("\nRun 'vaultik prune --remote' to remove orphaned blobs.\n")
 	}
 
 	return nil

internal/vaultik/prune.go

@@ -3,7 +3,6 @@ package vaultik
 import (
 	"encoding/json"
 	"fmt"
-	"os"
 	"strings"
 
 	"git.eeqj.de/sneak/vaultik/internal/log"
@@ -121,29 +120,29 @@ func (v *Vaultik) PruneBlobs(opts *PruneOptions) error {
 	if len(unreferencedBlobs) == 0 {
 		log.Info("No unreferenced blobs found")
 		if opts.JSON {
-			return outputPruneBlobsJSON(result)
+			return v.outputPruneBlobsJSON(result)
 		}
-		fmt.Println("No unreferenced blobs to remove.")
+		v.printlnStdout("No unreferenced blobs to remove.")
 		return nil
 	}
 
 	// Show what will be deleted
 	log.Info("Found unreferenced blobs", "count", len(unreferencedBlobs), "total_size", humanize.Bytes(uint64(totalSize)))
 	if !opts.JSON {
-		fmt.Printf("Found %d unreferenced blob(s) totaling %s\n", len(unreferencedBlobs), humanize.Bytes(uint64(totalSize)))
+		v.printfStdout("Found %d unreferenced blob(s) totaling %s\n", len(unreferencedBlobs), humanize.Bytes(uint64(totalSize)))
 	}
 
 	// Confirm unless --force is used (skip in JSON mode - require --force)
 	if !opts.Force && !opts.JSON {
-		fmt.Printf("\nDelete %d unreferenced blob(s)? [y/N] ", len(unreferencedBlobs))
+		v.printfStdout("\nDelete %d unreferenced blob(s)? [y/N] ", len(unreferencedBlobs))
 		var confirm string
-		if _, err := fmt.Scanln(&confirm); err != nil {
+		if _, err := v.scanStdin(&confirm); err != nil {
 			// Treat EOF or error as "no"
-			fmt.Println("Cancelled")
+			v.printlnStdout("Cancelled")
 			return nil
 		}
 		if strings.ToLower(confirm) != "y" {
-			fmt.Println("Cancelled")
+			v.printlnStdout("Cancelled")
 			return nil
 		}
 	}
@@ -185,20 +184,20 @@ func (v *Vaultik) PruneBlobs(opts *PruneOptions) error {
 	)
 
 	if opts.JSON {
-		return outputPruneBlobsJSON(result)
+		return v.outputPruneBlobsJSON(result)
 	}
 
-	fmt.Printf("\nDeleted %d blob(s) totaling %s\n", deletedCount, humanize.Bytes(uint64(deletedSize)))
+	v.printfStdout("\nDeleted %d blob(s) totaling %s\n", deletedCount, humanize.Bytes(uint64(deletedSize)))
 	if deletedCount < len(unreferencedBlobs) {
-		fmt.Printf("Failed to delete %d blob(s)\n", len(unreferencedBlobs)-deletedCount)
+		v.printfStdout("Failed to delete %d blob(s)\n", len(unreferencedBlobs)-deletedCount)
 	}
 
 	return nil
 }
 
 // outputPruneBlobsJSON outputs the prune result as JSON
-func outputPruneBlobsJSON(result *PruneBlobsResult) error {
-	encoder := json.NewEncoder(os.Stdout)
+func (v *Vaultik) outputPruneBlobsJSON(result *PruneBlobsResult) error {
+	encoder := json.NewEncoder(v.Stdout)
 	encoder.SetIndent("", "  ")
 	return encoder.Encode(result)
 }

internal/vaultik/restore.go

@@ -109,7 +109,11 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 
 	// Step 5: Restore files
 	result := &RestoreResult{}
-	blobCache := make(map[string][]byte) // Cache downloaded and decrypted blobs
+	blobCache, err := newBlobDiskCache(4 * v.Config.BlobSizeLimit.Int64())
+	if err != nil {
+		return fmt.Errorf("creating blob cache: %w", err)
+	}
+	defer func() { _ = blobCache.Close() }()
 
 	for i, file := range files {
 		if v.ctx.Err() != nil {
@@ -141,7 +145,7 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 		"duration", result.Duration,
 	)
 
-	_, _ = fmt.Fprintf(v.Stdout, "Restored %d files (%s) in %s\n",
+	v.printfStdout("Restored %d files (%s) in %s\n",
 		result.FilesRestored,
 		humanize.Bytes(uint64(result.BytesRestored)),
 		result.Duration.Round(time.Second),
@@ -154,14 +158,14 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 		}
 
 		if result.FilesFailed > 0 {
-			_, _ = fmt.Fprintf(v.Stdout, "\nVerification FAILED: %d files did not match expected checksums\n", result.FilesFailed)
+			v.printfStdout("\nVerification FAILED: %d files did not match expected checksums\n", result.FilesFailed)
 			for _, path := range result.FailedFiles {
-				_, _ = fmt.Fprintf(v.Stdout, "  - %s\n", path)
+				v.printfStdout("  - %s\n", path)
 			}
 			return fmt.Errorf("%d files failed verification", result.FilesFailed)
 		}
 
-		_, _ = fmt.Fprintf(v.Stdout, "Verified %d files (%s)\n",
+		v.printfStdout("Verified %d files (%s)\n",
 			result.FilesVerified,
 			humanize.Bytes(uint64(result.BytesVerified)),
 		)
@@ -299,7 +303,7 @@ func (v *Vaultik) restoreFile(
 	targetDir string,
 	identity age.Identity,
 	chunkToBlobMap map[string]*database.BlobChunk,
-	blobCache map[string][]byte,
+	blobCache *blobDiskCache,
 	result *RestoreResult,
 ) error {
 	// Calculate target path - use full original path under target directory
@@ -383,7 +387,7 @@ func (v *Vaultik) restoreRegularFile(
 	targetPath string,
 	identity age.Identity,
 	chunkToBlobMap map[string]*database.BlobChunk,
-	blobCache map[string][]byte,
+	blobCache *blobDiskCache,
 	result *RestoreResult,
 ) error {
 	// Get file chunks in order
@@ -417,13 +421,15 @@ func (v *Vaultik) restoreRegularFile(
 
 		// Download and decrypt blob if not cached
 		blobHashStr := blob.Hash.String()
-		blobData, ok := blobCache[blobHashStr]
+		blobData, ok := blobCache.Get(blobHashStr)
 		if !ok {
 			blobData, err = v.downloadBlob(ctx, blobHashStr, blob.CompressedSize, identity)
 			if err != nil {
 				return fmt.Errorf("downloading blob %s: %w", blobHashStr[:16], err)
 			}
-			blobCache[blobHashStr] = blobData
+			if putErr := blobCache.Put(blobHashStr, blobData); putErr != nil {
+				log.Debug("Failed to cache blob on disk", "hash", blobHashStr[:16], "error", putErr)
+			}
 			result.BlobsDownloaded++
 			result.BytesDownloaded += blob.CompressedSize
 		}
@@ -473,53 +479,6 @@ func (v *Vaultik) restoreRegularFile(
 	return nil
 }
 
-// BlobFetchResult holds the result of fetching and decrypting a blob.
-type BlobFetchResult struct {
-	Data           []byte
-	CompressedSize int64
-}
-
-// FetchAndDecryptBlob downloads a blob from storage, decrypts and decompresses it.
-func (v *Vaultik) FetchAndDecryptBlob(ctx context.Context, blobHash string, expectedSize int64, identity age.Identity) (*BlobFetchResult, error) {
-	// Construct blob path with sharding
-	blobPath := fmt.Sprintf("blobs/%s/%s/%s", blobHash[:2], blobHash[2:4], blobHash)
-
-	reader, err := v.Storage.Get(ctx, blobPath)
-	if err != nil {
-		return nil, fmt.Errorf("downloading blob: %w", err)
-	}
-	defer func() { _ = reader.Close() }()
-
-	// Read encrypted data
-	encryptedData, err := io.ReadAll(reader)
-	if err != nil {
-		return nil, fmt.Errorf("reading blob data: %w", err)
-	}
-
-	// Decrypt and decompress
-	blobReader, err := blobgen.NewReader(bytes.NewReader(encryptedData), identity)
-	if err != nil {
-		return nil, fmt.Errorf("creating decryption reader: %w", err)
-	}
-	defer func() { _ = blobReader.Close() }()
-
-	data, err := io.ReadAll(blobReader)
-	if err != nil {
-		return nil, fmt.Errorf("decrypting blob: %w", err)
-	}
-
-	log.Debug("Downloaded and decrypted blob",
-		"hash", blobHash[:16],
-		"encrypted_size", humanize.Bytes(uint64(len(encryptedData))),
-		"decrypted_size", humanize.Bytes(uint64(len(data))),
-	)
-
-	return &BlobFetchResult{
-		Data:           data,
-		CompressedSize: int64(len(encryptedData)),
-	}, nil
-}
-
 // downloadBlob downloads and decrypts a blob
 func (v *Vaultik) downloadBlob(ctx context.Context, blobHash string, expectedSize int64, identity age.Identity) ([]byte, error) {
 	result, err := v.FetchAndDecryptBlob(ctx, blobHash, expectedSize, identity)
@@ -558,7 +517,7 @@ func (v *Vaultik) verifyRestoredFiles(
 		"files", len(regularFiles),
 		"bytes", humanize.Bytes(uint64(totalBytes)),
 	)
-	_, _ = fmt.Fprintf(v.Stdout, "\nVerifying %d files (%s)...\n",
+	v.printfStdout("\nVerifying %d files (%s)...\n",
 		len(regularFiles),
 		humanize.Bytes(uint64(totalBytes)),
 	)
@@ -569,13 +528,13 @@ func (v *Vaultik) verifyRestoredFiles(
 		bar = progressbar.NewOptions64(
 			totalBytes,
 			progressbar.OptionSetDescription("Verifying"),
-			progressbar.OptionSetWriter(os.Stderr),
+			progressbar.OptionSetWriter(v.Stderr),
 			progressbar.OptionShowBytes(true),
 			progressbar.OptionShowCount(),
 			progressbar.OptionSetWidth(40),
 			progressbar.OptionThrottle(100*time.Millisecond),
 			progressbar.OptionOnCompletion(func() {
-				fmt.Fprint(os.Stderr, "\n")
+				v.printfStderr("\n")
 			}),
 			progressbar.OptionSetRenderBlankState(true),
 		)

internal/vaultik/snapshot.go

@@ -545,7 +545,7 @@ func (v *Vaultik) PurgeSnapshots(keepLatest bool, olderThan string, force bool)
 	if !force {
 		v.printfStdout("\nDelete %d snapshot(s)? [y/N] ", len(toDelete))
 		var confirm string
-		if _, err := fmt.Scanln(&confirm); err != nil {
+		if _, err := v.scanStdin(&confirm); err != nil {
 			// Treat EOF or error as "no"
 			v.printlnStdout("Cancelled")
 			return nil
@@ -851,7 +851,7 @@ func (v *Vaultik) RemoveSnapshot(snapshotID string, opts *RemoveOptions) (*Remov
 			v.printfStdout("Remove snapshot '%s' from local database? [y/N] ", snapshotID)
 		}
 		var confirm string
-		if err := v.scanlnStdin(&confirm); err != nil {
+		if _, err := v.scanStdin(&confirm); err != nil {
 			v.printlnStdout("Cancelled")
 			return result, nil
 		}

internal/vaultik/vaultik.go

@@ -129,12 +129,6 @@ func (v *Vaultik) GetFilesystem() afero.Fs {
 	return v.Fs
 }
 
-// Outputf writes formatted output to stdout for user-facing messages.
-// This should be used for all non-log user output.
-func (v *Vaultik) Outputf(format string, args ...any) {
-	_, _ = fmt.Fprintf(v.Stdout, format, args...)
-}
-
 // printfStdout writes formatted output to stdout.
 func (v *Vaultik) printfStdout(format string, args ...any) {
 	_, _ = fmt.Fprintf(v.Stdout, format, args...)
@@ -145,22 +139,14 @@ func (v *Vaultik) printlnStdout(args ...any) {
 	_, _ = fmt.Fprintln(v.Stdout, args...)
 }
 
-// scanlnStdin reads a line from stdin into the provided string pointer.
-func (v *Vaultik) scanlnStdin(s *string) error {
-	_, err := fmt.Fscanln(v.Stdin, s)
-	return err
+// printfStderr writes formatted output to stderr.
+func (v *Vaultik) printfStderr(format string, args ...any) {
+	_, _ = fmt.Fprintf(v.Stderr, format, args...)
 }
 
-// FetchBlob downloads a blob from storage and returns a reader for the encrypted data.
-func (v *Vaultik) FetchBlob(ctx context.Context, blobHash string, expectedSize int64) (io.ReadCloser, int64, error) {
-	blobPath := fmt.Sprintf("blobs/%s/%s/%s", blobHash[:2], blobHash[2:4], blobHash)
-
-	reader, err := v.Storage.Get(ctx, blobPath)
-	if err != nil {
-		return nil, 0, fmt.Errorf("downloading blob: %w", err)
-	}
-
-	return reader, expectedSize, nil
+// scanStdin reads a line of input from stdin.
+func (v *Vaultik) scanStdin(a ...any) (int, error) {
+	return fmt.Fscanln(v.Stdin, a...)
 }
 
 // TestVaultik wraps a Vaultik with captured stdout/stderr for testing

internal/vaultik/verify.go

@@ -58,14 +58,14 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 	)
 
 	if !opts.JSON {
-		v.Outputf("Deep verification of snapshot: %s\n\n", snapshotID)
+		v.printfStdout("Deep verification of snapshot: %s\n\n", snapshotID)
 	}
 
 	// Step 1: Download manifest
 	manifestPath := fmt.Sprintf("metadata/%s/manifest.json.zst", snapshotID)
 	log.Info("Downloading manifest", "path", manifestPath)
 	if !opts.JSON {
-		v.Outputf("Downloading manifest...\n")
+		v.printfStdout("Downloading manifest...\n")
 	}
 
 	manifestReader, err := v.Storage.Get(v.ctx, manifestPath)
@@ -95,14 +95,14 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 		"manifest_total_size", humanize.Bytes(uint64(manifest.TotalCompressedSize)),
 	)
 	if !opts.JSON {
-		v.Outputf("Manifest loaded: %d blobs (%s)\n", manifest.BlobCount, humanize.Bytes(uint64(manifest.TotalCompressedSize)))
+		v.printfStdout("Manifest loaded: %d blobs (%s)\n", manifest.BlobCount, humanize.Bytes(uint64(manifest.TotalCompressedSize)))
 	}
 
 	// Step 2: Download and decrypt database (authoritative source)
 	dbPath := fmt.Sprintf("metadata/%s/db.zst.age", snapshotID)
 	log.Info("Downloading encrypted database", "path", dbPath)
 	if !opts.JSON {
-		v.Outputf("Downloading and decrypting database...\n")
+		v.printfStdout("Downloading and decrypting database...\n")
 	}
 
 	dbReader, err := v.Storage.Get(v.ctx, dbPath)
@@ -155,8 +155,8 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 		"db_total_size", humanize.Bytes(uint64(totalSize)),
 	)
 	if !opts.JSON {
-		v.Outputf("Database loaded: %d blobs (%s)\n", len(dbBlobs), humanize.Bytes(uint64(totalSize)))
-		v.Outputf("Verifying manifest against database...\n")
+		v.printfStdout("Database loaded: %d blobs (%s)\n", len(dbBlobs), humanize.Bytes(uint64(totalSize)))
+		v.printfStdout("Verifying manifest against database...\n")
 	}
 
 	// Step 4: Verify manifest matches database
@@ -171,8 +171,8 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 
 	// Step 5: Verify all blobs exist in S3 (using database as source)
 	if !opts.JSON {
-		v.Outputf("Manifest verified.\n")
-		v.Outputf("Checking blob existence in remote storage...\n")
+		v.printfStdout("Manifest verified.\n")
+		v.printfStdout("Checking blob existence in remote storage...\n")
 	}
 	if err := v.verifyBlobExistenceFromDB(dbBlobs); err != nil {
 		result.Status = "failed"
@@ -185,8 +185,8 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 
 	// Step 6: Deep verification - download and verify blob contents
 	if !opts.JSON {
-		v.Outputf("All blobs exist.\n")
-		v.Outputf("Downloading and verifying blob contents (%d blobs, %s)...\n", len(dbBlobs), humanize.Bytes(uint64(totalSize)))
+		v.printfStdout("All blobs exist.\n")
+		v.printfStdout("Downloading and verifying blob contents (%d blobs, %s)...\n", len(dbBlobs), humanize.Bytes(uint64(totalSize)))
 	}
 	if err := v.performDeepVerificationFromDB(dbBlobs, tempDB.DB, opts); err != nil {
 		result.Status = "failed"
@@ -211,10 +211,10 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 		"blobs_verified", len(dbBlobs),
 	)
 
-	v.Outputf("\n✓ Verification completed successfully\n")
-	v.Outputf("  Snapshot:       %s\n", snapshotID)
-	v.Outputf("  Blobs verified: %d\n", len(dbBlobs))
-	v.Outputf("  Total size:     %s\n", humanize.Bytes(uint64(totalSize)))
+	v.printfStdout("\n✓ Verification completed successfully\n")
+	v.printfStdout("  Snapshot:       %s\n", snapshotID)
+	v.printfStdout("  Blobs verified: %d\n", len(dbBlobs))
+	v.printfStdout("  Total size:     %s\n", humanize.Bytes(uint64(totalSize)))
 
 	return nil
 }
@@ -569,7 +569,7 @@ func (v *Vaultik) performDeepVerificationFromDB(blobs []snapshot.BlobInfo, db *s
 		)
 
 		if !opts.JSON {
-			v.Outputf("  Verified %d/%d blobs (%d remaining) - %s/%s - elapsed %s, eta %s\n",
+			v.printfStdout("  Verified %d/%d blobs (%d remaining) - %s/%s - elapsed %s, eta %s\n",
 				i+1, len(blobs), remaining,
 				humanize.Bytes(uint64(bytesProcessed)),
 				humanize.Bytes(uint64(totalBytesExpected)),