feat(restore): cross-platform restore via dump engine rebuild (#606)

Restore previously required the dump's origin OS, overlaying keys onto locally-discovered browsers. It now rebuilds Chromium engines from the dump's vaults (v2 adds engine kind), so copied data or an archive zip decrypts on any OS.

browser/browser.go

@@ -91,9 +91,12 @@ func discoverFromConfigs(configs []types.BrowserConfig, opts DiscoverOptions) ([
 }
 
 // KeyManager is implemented by installations accepting external master-key retrievers (Chromium only).
+// BrowserKey/Kind expose the identity a portable dump needs to rebuild the engine off the platform table.
 type KeyManager interface {
 	SetRetrievers(masterkey.Retrievers)
 	ExportKeys() (masterkey.MasterKeys, error)
+	BrowserKey() string
+	Kind() types.BrowserKind
 }
 
 // KeychainPasswordReceiver is implemented by installations that need the macOS login password (Safari only).

browser/chromium/chromium.go

@@ -54,9 +54,10 @@ func NewBrowser(cfg types.BrowserConfig) (*Browser, error) {
 // Extract; unused tiers stay nil.
 func (b *Browser) SetRetrievers(r masterkey.Retrievers) { b.retrievers = r }
 
-func (b *Browser) BrowserName() string { return b.cfg.Name }
-func (b *Browser) BrowserKey() string  { return b.cfg.Key }
-func (b *Browser) UserDataDir() string { return b.cfg.UserDataDir }
+func (b *Browser) BrowserName() string     { return b.cfg.Name }
+func (b *Browser) BrowserKey() string      { return b.cfg.Key }
+func (b *Browser) UserDataDir() string     { return b.cfg.UserDataDir }
+func (b *Browser) Kind() types.BrowserKind { return b.cfg.Kind }
 
 // Profiles returns the identity of every profile in this installation.
 func (b *Browser) Profiles() []types.Profile {
@@ -162,12 +163,25 @@ func discoverProfiles(userDataDir string, sources map[types.Category][]sourcePat
 		}
 	}
 
-	// Flat layout fallback (older Opera): data files directly in userDataDir.
-	// Opera stores data alongside Local State in userDataDir itself, so check
-	// for any known source file instead of Preferences.
+	// Flat layout (older Opera): data files directly under userDataDir with no profile subdir. Check the
+	// root before the subdir fallback so a stray source-bearing subdir can't suppress root discovery.
 	if len(profiles) == 0 && hasAnySource(sources, userDataDir) {
 		profiles = append(profiles, userDataDir)
 	}
+
+	// Restored/copied trees may omit the Preferences marker (it is no extraction source). When the marker
+	// scan and flat-layout check both find nothing, treat any source-bearing subdir as a profile.
+	if len(profiles) == 0 {
+		for _, e := range entries {
+			if !e.IsDir() || isSkippedDir(e.Name()) {
+				continue
+			}
+			dir := filepath.Join(userDataDir, e.Name())
+			if hasAnySource(sources, dir) {
+				profiles = append(profiles, dir)
+			}
+		}
+	}
 	return profiles
 }
 

browser/chromium/chromium_test.go

@@ -237,6 +237,50 @@ func TestNewBrowsers(t *testing.T) {
 	}
 }
 
+// ---------------------------------------------------------------------------
+// discoverProfiles: fallback boundaries (marker-less copies, flat-layout precedence)
+// ---------------------------------------------------------------------------
+
+func TestDiscoverProfiles(t *testing.T) {
+	t.Run("markerless multi-subdir resolves all source-bearing dirs", func(t *testing.T) {
+		dir := t.TempDir()
+		mkFile(dir, "Default", "History")
+		mkFile(dir, "Profile 1", "History")
+		assert.Len(t, discoverProfiles(dir, chromiumSources), 2)
+	})
+
+	t.Run("marker present keeps fallback dormant", func(t *testing.T) {
+		dir := t.TempDir()
+		mkFile(dir, "Default", "Preferences")
+		mkFile(dir, "Default", "History")
+		mkFile(dir, "NotAProfile", "History")
+		got := discoverProfiles(dir, chromiumSources)
+		require.Len(t, got, 1)
+		assert.Equal(t, filepath.Join(dir, "Default"), got[0])
+	})
+
+	t.Run("skipped dir ignored by markerless fallback", func(t *testing.T) {
+		dir := t.TempDir()
+		mkFile(dir, "System Profile", "History")
+		assert.Empty(t, discoverProfiles(dir, chromiumSources))
+	})
+
+	t.Run("sourceless subdir ignored", func(t *testing.T) {
+		dir := t.TempDir()
+		mkDir(dir, "Crashpad")
+		assert.Empty(t, discoverProfiles(dir, chromiumSources))
+	})
+
+	t.Run("flat-layout root wins over source-bearing subdir", func(t *testing.T) {
+		dir := t.TempDir()
+		mkFile(dir, "History")
+		mkFile(dir, "Subthing", "History")
+		got := discoverProfiles(dir, chromiumSources)
+		require.Len(t, got, 1)
+		assert.Equal(t, dir, got[0], "flat-layout root must win; subdir must not hijack discovery")
+	})
+}
+
 // ---------------------------------------------------------------------------
 // Test helpers
 // ---------------------------------------------------------------------------

browser/keydump.go

@@ -1,10 +1,14 @@
 package browser
 
 import (
-	"runtime"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
 
 	"github.com/moond4rk/hackbrowserdata/log"
 	"github.com/moond4rk/hackbrowserdata/masterkey"
+	"github.com/moond4rk/hackbrowserdata/types"
 )
 
 // BuildDump exports one Vault per installation (Firefox/Safari, lacking KeyManager, are skipped).
@@ -28,8 +32,14 @@ func BuildDump(browsers []Browser) masterkey.Dump {
 		if !mk.HasAny() {
 			continue
 		}
+		kind, err := kindToDump(km.Kind())
+		if err != nil {
+			log.Warnf("dump-keys: %s: %v", b.BrowserName(), err)
+			continue
+		}
 		dump.Vaults = append(dump.Vaults, masterkey.Vault{
-			Browser:     b.BrowserName(),
+			Browser:     km.BrowserKey(),
+			Kind:        kind,
 			UserDataDir: b.UserDataDir(),
 			Profiles:    profileNames(b),
 			Keys:        mk,
@@ -47,46 +57,102 @@ func profileNames(b Browser) []string {
 	return names
 }
 
-// ApplyDump overlays StaticRetrievers from dump onto matching installations (Firefox/Safari skipped).
-// Match is by (BrowserName, UserDataDir); on miss — commonly a cross-host path mismatch (Windows vs
-// POSIX, or a relocated dir via -p) — it falls back to the sole vault for that browser name. No match
-// → warn and leave the platform retrievers in place.
-func ApplyDump(browsers []Browser, dump masterkey.Dump) {
-	if dump.Host.OS != "" && dump.Host.OS != runtime.GOOS {
-		log.Infof("apply-keys: dump created on %s/%s; current host is %s/%s",
-			dump.Host.OS, dump.Host.Arch, runtime.GOOS, runtime.GOARCH)
+// BuildFromDump reconstructs Chromium engines straight from a dump's vaults, rooted at copied data
+// instead of the local platform table — this is what lets an analyst host decrypt a browser its OS
+// never installs. filter is a browser key ("" or "all" = every vault); a filter matching no vault is
+// an error rather than silent empty output.
+//
+// Data layout is resolved two ways. When dataDir holds per-key subdirs (the archive layout), each
+// vault is rooted at dataDir/<key>. Otherwise dataDir is treated as one browser's User Data (a
+// hand-copied folder), which is unambiguous only for a single vault — so filter must pick one.
+func BuildFromDump(dump masterkey.Dump, dataDir, filter string) ([]Browser, error) {
+	filter = strings.ToLower(filter)
+	if filter == "all" {
+		filter = ""
 	}
-	vaultIndex := make(map[string]*masterkey.Vault, len(dump.Vaults))
-	vaultsByBrowser := make(map[string][]*masterkey.Vault)
-	for i := range dump.Vaults {
-		v := &dump.Vaults[i]
-		vaultIndex[v.Browser+"|"+v.UserDataDir] = v
-		vaultsByBrowser[v.Browser] = append(vaultsByBrowser[v.Browser], v)
-	}
-	for _, b := range browsers {
-		km, ok := b.(KeyManager)
-		if !ok {
+
+	var selected []masterkey.Vault
+	for _, v := range dump.Vaults {
+		if filter != "" && !strings.EqualFold(v.Browser, filter) {
 			continue
 		}
-		v, found := vaultIndex[b.BrowserName()+"|"+b.UserDataDir()]
-		if !found {
-			if candidates := vaultsByBrowser[b.BrowserName()]; len(candidates) == 1 {
-				v = candidates[0]
-				log.Infof("apply-keys: %s using sole vault for browser (dump path %q != local %q)",
-					b.BrowserName(), v.UserDataDir, b.UserDataDir())
-				found = true
+		selected = append(selected, v)
+	}
+	if filter != "" && len(selected) == 0 {
+		return nil, fmt.Errorf("no vault for browser %q in keys (have: %s)", filter, vaultKeys(dump))
+	}
+
+	if !dirExists(dataDir) {
+		return nil, fmt.Errorf("data dir %q does not exist", dataDir)
+	}
+
+	archiveLayout := isArchiveLayout(dataDir, selected)
+	if !archiveLayout && len(selected) > 1 {
+		return nil, fmt.Errorf("--data-dir %q has no per-browser subdir but keys has %d browsers; "+
+			"point it at the archive root, or use -b <browser> for one browser's User Data (have: %s)",
+			dataDir, len(selected), vaultKeys(dump))
+	}
+
+	var browsers []Browser
+	for _, v := range selected {
+		root := dataDir
+		if archiveLayout {
+			root = filepath.Join(dataDir, strings.ToLower(v.Browser))
+			if !dirExists(root) {
+				log.Warnf("restore: %s has no data under %s, skipping", v.Browser, root)
+				continue
 			}
 		}
-		if !found {
-			log.Warnf("apply-keys: %s no matching vault in dump", b.BrowserName())
+		kind, err := kindFromDump(v.Kind)
+		if err != nil {
+			log.Warnf("restore: %s: %v", v.Browser, err)
 			continue
 		}
-		km.SetRetrievers(masterkey.Retrievers{
-			V10: maybeStaticRetriever(v.Keys.V10),
-			V11: maybeStaticRetriever(v.Keys.V11),
-			V20: maybeStaticRetriever(v.Keys.V20),
-		})
+		cfg := types.BrowserConfig{
+			Key:         strings.ToLower(v.Browser),
+			Name:        v.Browser,
+			Kind:        kind,
+			UserDataDir: root,
+		}
+		b, err := newBrowser(cfg)
+		if err != nil {
+			log.Errorf("restore: build %s: %v", v.Browser, err)
+			continue
+		}
+		if b == nil {
+			log.Warnf("restore: %s found no profiles under %s", v.Browser, root)
+			continue
+		}
+		if km, ok := b.(KeyManager); ok {
+			km.SetRetrievers(retrieversFromKeys(v.Keys))
+		}
+		browsers = append(browsers, b)
 	}
+	return browsers, nil
+}
+
+// isArchiveLayout reports whether dataDir uses the archive layout — one per-browser subdir named by
+// the vault key — rather than a raw single-browser User Data copy.
+func isArchiveLayout(dataDir string, vaults []masterkey.Vault) bool {
+	for _, v := range vaults {
+		if dirExists(filepath.Join(dataDir, strings.ToLower(v.Browser))) {
+			return true
+		}
+	}
+	return false
+}
+
+func vaultKeys(dump masterkey.Dump) string {
+	keys := make([]string, 0, len(dump.Vaults))
+	for _, v := range dump.Vaults {
+		keys = append(keys, strings.ToLower(v.Browser))
+	}
+	return strings.Join(keys, ", ")
+}
+
+func dirExists(path string) bool {
+	info, err := os.Stat(path)
+	return err == nil && info.IsDir()
 }
 
 // maybeStaticRetriever wraps non-empty key bytes as a StaticRetriever; an empty/nil key returns nil
@@ -97,3 +163,35 @@ func maybeStaticRetriever(key []byte) masterkey.Retriever {
 	}
 	return masterkey.NewStaticRetriever(key)
 }
+
+// retrieversFromKeys maps a vault's per-tier key bytes to static retrievers; an absent tier stays nil
+// so NewMasterKeys keeps treating it as "not applicable".
+func retrieversFromKeys(mk masterkey.MasterKeys) masterkey.Retrievers {
+	return masterkey.Retrievers{
+		V10: maybeStaticRetriever(mk.V10),
+		V11: maybeStaticRetriever(mk.V11),
+		V20: maybeStaticRetriever(mk.V20),
+	}
+}
+
+func kindToDump(k types.BrowserKind) (string, error) {
+	switch k {
+	case types.Chromium, types.ChromiumYandex, types.ChromiumOpera:
+		return k.String(), nil
+	default:
+		return "", fmt.Errorf("engine kind %s is not exportable", k)
+	}
+}
+
+// dumpableKinds are the engine kinds a vault may carry; kindFromDump reverses BrowserKind.String()
+// over exactly these, keeping the wire vocabulary single-sourced in the types enum.
+var dumpableKinds = []types.BrowserKind{types.Chromium, types.ChromiumYandex, types.ChromiumOpera}
+
+func kindFromDump(s string) (types.BrowserKind, error) {
+	for _, k := range dumpableKinds {
+		if k.String() == s {
+			return k, nil
+		}
+	}
+	return 0, fmt.Errorf("unknown engine kind %q", s)
+}

browser/keydump_test.go

@@ -3,7 +3,10 @@ package browser
 import (
 	"bytes"
 	"errors"
+	"os"
+	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 
 	"github.com/moond4rk/hackbrowserdata/masterkey"
@@ -44,6 +47,8 @@ func (m *mockBrowser) CountEntries(_ []types.Category) ([]types.CountResult, err
 
 type mockChromiumBrowser struct {
 	mockBrowser
+	key                string
+	kind               types.BrowserKind
 	keys               masterkey.MasterKeys
 	exportErr          error
 	calls              int
@@ -59,6 +64,15 @@ func (m *mockChromiumBrowser) ExportKeys() (masterkey.MasterKeys, error) {
 	return m.keys, m.exportErr
 }
 
+func (m *mockChromiumBrowser) BrowserKey() string {
+	if m.key != "" {
+		return m.key
+	}
+	return strings.ToLower(m.name)
+}
+
+func (m *mockChromiumBrowser) Kind() types.BrowserKind { return m.kind }
+
 func TestBuildDump_Empty(t *testing.T) {
 	dump := BuildDump(nil)
 	if dump.Version != masterkey.DumpVersion {
@@ -84,9 +98,12 @@ func TestBuildDump_SingleChromium(t *testing.T) {
 		t.Fatalf("Vaults len = %d, want 1", len(dump.Vaults))
 	}
 	inst := dump.Vaults[0]
-	if inst.Browser != chromeName || inst.UserDataDir != testUDD {
+	if !strings.EqualFold(inst.Browser, chromeName) || inst.UserDataDir != testUDD {
 		t.Errorf("inst metadata = %+v", inst)
 	}
+	if inst.Kind != "chromium" {
+		t.Errorf("Kind = %q, want chromium", inst.Kind)
+	}
 	if len(inst.Profiles) != 1 || inst.Profiles[0] != testProfileDefault {
 		t.Errorf("Profiles = %v", inst.Profiles)
 	}
@@ -129,8 +146,8 @@ func TestBuildDump_SkipsNonKeyManager(t *testing.T) {
 	if len(dump.Vaults) != 1 {
 		t.Fatalf("Vaults len = %d, want 1 (firefox skipped)", len(dump.Vaults))
 	}
-	if dump.Vaults[0].Browser != chromeName {
-		t.Errorf("Browser = %q, want %q", dump.Vaults[0].Browser, chromeName)
+	if !strings.EqualFold(dump.Vaults[0].Browser, chromeName) {
+		t.Errorf("Browser = %q, want %q", dump.Vaults[0].Browser, strings.ToLower(chromeName))
 	}
 }
 
@@ -149,8 +166,8 @@ func TestBuildDump_SkipsExportError(t *testing.T) {
 	if len(dump.Vaults) != 1 {
 		t.Fatalf("Vaults len = %d, want 1 (failing browser skipped)", len(dump.Vaults))
 	}
-	if dump.Vaults[0].Browser != chromeName {
-		t.Errorf("Browser = %q, want %q", dump.Vaults[0].Browser, chromeName)
+	if !strings.EqualFold(dump.Vaults[0].Browser, chromeName) {
+		t.Errorf("Browser = %q, want %q", dump.Vaults[0].Browser, strings.ToLower(chromeName))
 	}
 }
 
@@ -178,6 +195,9 @@ func TestBuildDump_JSONRoundTrip(t *testing.T) {
 	if len(parsed.Vaults) != 1 {
 		t.Fatalf("Vaults len = %d", len(parsed.Vaults))
 	}
+	if parsed.Vaults[0].Kind != "chromium" {
+		t.Errorf("Kind round-trip: got %q, want chromium", parsed.Vaults[0].Kind)
+	}
 	if !bytes.Equal(parsed.Vaults[0].Keys.V10, dump.Vaults[0].Keys.V10) {
 		t.Errorf("V10 round-trip mismatch")
 	}
@@ -209,123 +229,168 @@ func TestBuildDump_PartialKeys(t *testing.T) {
 	}
 }
 
-func TestApplyDump_Match(t *testing.T) {
-	b := &mockChromiumBrowser{
-		mockBrowser: mockBrowser{name: chromeName, userDataDir: testUDD, profiles: []string{testProfileDefault}},
+func TestKindDumpRoundTrip(t *testing.T) {
+	for _, k := range []types.BrowserKind{types.Chromium, types.ChromiumYandex, types.ChromiumOpera} {
+		s, err := kindToDump(k)
+		if err != nil {
+			t.Fatalf("kindToDump(%d): %v", k, err)
+		}
+		got, err := kindFromDump(s)
+		if err != nil || got != k {
+			t.Errorf("round trip %d -> %q -> %d (err %v)", k, s, got, err)
+		}
 	}
-	dump := masterkey.Dump{
-		Vaults: []masterkey.Vault{
-			{Browser: chromeName, UserDataDir: testUDD, Keys: masterkey.MasterKeys{V10: []byte("v10-from-dump")}},
-		},
+	if _, err := kindToDump(types.Firefox); err == nil {
+		t.Error("kindToDump(Firefox) should error")
 	}
-	ApplyDump([]Browser{b}, dump)
-
-	if b.receivedRetrievers.V10 == nil {
-		t.Fatal("V10 retriever should be set from matching vault")
-	}
-	got, err := b.receivedRetrievers.V10.RetrieveKey(masterkey.Hints{})
-	if err != nil || string(got) != "v10-from-dump" {
-		t.Errorf("V10.RetrieveKey() = %q, err = %v, want %q", got, err, "v10-from-dump")
-	}
-	if b.receivedRetrievers.V11 != nil {
-		t.Errorf("V11 should be nil (tier not in dump), got %v", b.receivedRetrievers.V11)
+	if _, err := kindFromDump("nope"); err == nil {
+		t.Error("kindFromDump(nope) should error")
 	}
 }
 
-func TestApplyDump_MissingVault(t *testing.T) {
-	b := &mockChromiumBrowser{
-		mockBrowser: mockBrowser{name: chromeName, userDataDir: testUDD, profiles: []string{testProfileDefault}},
-	}
-	dump := masterkey.Dump{
-		Vaults: []masterkey.Vault{
-			{Browser: testEdgeName, UserDataDir: "/edge", Keys: masterkey.MasterKeys{V10: []byte("v10")}},
-		},
-	}
-	ApplyDump([]Browser{b}, dump)
+func TestRetrieversFromKeys(t *testing.T) {
+	r := retrieversFromKeys(masterkey.MasterKeys{V10: []byte("k10"), V20: []byte("k20")})
 
-	if b.receivedRetrievers.V10 != nil {
-		t.Errorf("V10 should remain nil when no matching vault, got %v", b.receivedRetrievers.V10)
+	if r.V10 == nil || r.V20 == nil {
+		t.Fatal("V10 and V20 retrievers should be set from non-empty keys")
+	}
+	if r.V11 != nil {
+		t.Error("V11 retriever should be nil when the key is absent")
+	}
+	if got, _ := r.V10.RetrieveKey(masterkey.Hints{}); string(got) != "k10" {
+		t.Errorf("V10 key = %q, want k10", got)
+	}
+	if got, _ := r.V20.RetrieveKey(masterkey.Hints{}); string(got) != "k20" {
+		t.Errorf("V20 key = %q, want k20", got)
 	}
 }
 
-func TestApplyDump_NonKeyManagerSkipped(t *testing.T) {
-	firefox := &mockBrowser{name: firefoxName, userDataDir: "/ff", profiles: []string{"default-release"}}
-	dump := masterkey.Dump{
-		Vaults: []masterkey.Vault{
-			{Browser: firefoxName, UserDataDir: "/ff", Keys: masterkey.MasterKeys{V10: []byte("v10")}},
-		},
-	}
-	// firefox does not implement KeyManager; ApplyDump must not panic and must not attempt injection.
-	ApplyDump([]Browser{firefox}, dump)
-}
-
-func TestApplyDump_RoundTrip(t *testing.T) {
-	src := &mockChromiumBrowser{
-		mockBrowser: mockBrowser{name: chromeName, userDataDir: testUDD, profiles: []string{testProfileDefault}},
-		keys:        masterkey.MasterKeys{V10: []byte("v10-rt"), V20: []byte("v20-rt")},
-	}
-	dump := BuildDump([]Browser{src})
-
-	dst := &mockChromiumBrowser{
-		mockBrowser: mockBrowser{name: chromeName, userDataDir: testUDD, profiles: []string{testProfileDefault}},
-	}
-	ApplyDump([]Browser{dst}, dump)
-
-	v10, _ := dst.receivedRetrievers.V10.RetrieveKey(masterkey.Hints{})
-	if string(v10) != "v10-rt" {
-		t.Errorf("V10 round-trip: got %q, want v10-rt", v10)
-	}
-	v20, _ := dst.receivedRetrievers.V20.RetrieveKey(masterkey.Hints{})
-	if string(v20) != "v20-rt" {
-		t.Errorf("V20 round-trip: got %q, want v20-rt", v20)
-	}
-	if dst.receivedRetrievers.V11 != nil {
-		t.Errorf("V11 should be nil (not in source keys), got %v", dst.receivedRetrievers.V11)
+// makeUserData writes a minimal Chromium profile tree: a Preferences marker plus History (a real
+// extraction source, so the profile resolves) under each named profile dir.
+func makeUserData(t *testing.T, root string, profiles ...string) {
+	t.Helper()
+	for _, p := range profiles {
+		dir := filepath.Join(root, p)
+		if err := os.MkdirAll(dir, 0o755); err != nil {
+			t.Fatal(err)
+		}
+		for _, f := range []string{"Preferences", "History"} {
+			if err := os.WriteFile(filepath.Join(dir, f), []byte("x"), 0o600); err != nil {
+				t.Fatal(err)
+			}
+		}
 	}
 }
 
-func TestApplyDump_FallbackOnPathMismatch(t *testing.T) {
-	// Cross-host scenario: dump was created on Windows but is applied on Linux/macOS where the
-	// UserDataDir literally differs. With a single vault for the browser, ApplyDump should still
-	// inject — otherwise the primary cross-host use case fails silently.
-	b := &mockChromiumBrowser{
-		mockBrowser: mockBrowser{name: chromeName, userDataDir: "/local/chrome", profiles: []string{testProfileDefault}},
-	}
-	dump := masterkey.Dump{
-		Vaults: []masterkey.Vault{
-			{
-				Browser:     chromeName,
-				UserDataDir: `C:\Users\foo\AppData\Local\Google\Chrome\User Data`,
-				Keys:        masterkey.MasterKeys{V10: []byte("v10-fallback")},
-			},
-		},
-	}
-	ApplyDump([]Browser{b}, dump)
+func TestBuildFromDump_ConventionMultiBrowser(t *testing.T) {
+	dataDir := t.TempDir()
+	makeUserData(t, filepath.Join(dataDir, "chrome"), testProfileDefault)
+	makeUserData(t, filepath.Join(dataDir, "edge"), testProfileDefault)
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "chrome", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("c")}},
+		{Browser: "edge", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("e")}},
+	}}
 
-	if b.receivedRetrievers.V10 == nil {
-		t.Fatal("V10 retriever should be set via single-vault fallback")
+	browsers, err := BuildFromDump(dump, dataDir, "")
+	if err != nil {
+		t.Fatalf("BuildFromDump: %v", err)
 	}
-	got, err := b.receivedRetrievers.V10.RetrieveKey(masterkey.Hints{})
-	if err != nil || string(got) != "v10-fallback" {
-		t.Errorf("V10.RetrieveKey() = %q, err = %v, want %q", got, err, "v10-fallback")
+	if len(browsers) != 2 {
+		t.Fatalf("got %d browsers, want 2", len(browsers))
 	}
 }
 
-func TestApplyDump_NoFallbackWhenAmbiguous(t *testing.T) {
-	// Two Chrome vaults in the dump and no exact path match — ApplyDump must not guess which
-	// installation the local browser corresponds to.
-	b := &mockChromiumBrowser{
-		mockBrowser: mockBrowser{name: chromeName, userDataDir: "/local/chrome", profiles: []string{testProfileDefault}},
-	}
-	dump := masterkey.Dump{
-		Vaults: []masterkey.Vault{
-			{Browser: chromeName, UserDataDir: "/path/a", Keys: masterkey.MasterKeys{V10: []byte("a")}},
-			{Browser: chromeName, UserDataDir: "/path/b", Keys: masterkey.MasterKeys{V10: []byte("b")}},
-		},
-	}
-	ApplyDump([]Browser{b}, dump)
+// TestBuildFromDump_ForeignKindNoPlatformTable proves restore never consults platformBrowsers():
+// sogou is Windows-only yet reconstructs from its vault on any OS.
+func TestBuildFromDump_ForeignKindNoPlatformTable(t *testing.T) {
+	dataDir := t.TempDir()
+	makeUserData(t, filepath.Join(dataDir, "sogou"), testProfileDefault)
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "sogou", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("k")}},
+	}}
 
-	if b.receivedRetrievers.V10 != nil {
-		t.Errorf("V10 should remain nil when fallback is ambiguous, got %v", b.receivedRetrievers.V10)
+	browsers, err := BuildFromDump(dump, dataDir, "")
+	if err != nil {
+		t.Fatalf("BuildFromDump: %v", err)
+	}
+	if len(browsers) != 1 {
+		t.Fatalf("got %d browsers, want 1", len(browsers))
+	}
+	if browsers[0].BrowserName() != "sogou" {
+		t.Errorf("BrowserName = %q, want sogou", browsers[0].BrowserName())
+	}
+}
+
+func TestBuildFromDump_RawSingleBrowser(t *testing.T) {
+	dataDir := t.TempDir()
+	makeUserData(t, dataDir, testProfileDefault)
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "chrome", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("c")}},
+	}}
+
+	browsers, err := BuildFromDump(dump, dataDir, "chrome")
+	if err != nil {
+		t.Fatalf("BuildFromDump: %v", err)
+	}
+	if len(browsers) != 1 {
+		t.Fatalf("got %d browsers, want 1", len(browsers))
+	}
+	if browsers[0].UserDataDir() != dataDir {
+		t.Errorf("UserDataDir = %q, want %q (raw root)", browsers[0].UserDataDir(), dataDir)
+	}
+}
+
+func TestBuildFromDump_UnknownBrowserErrors(t *testing.T) {
+	dataDir := t.TempDir()
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "chrome", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("c")}},
+	}}
+	if _, err := BuildFromDump(dump, dataDir, "sogou"); err == nil {
+		t.Fatal("expected error for -b matching no vault")
+	}
+}
+
+func TestBuildFromDump_RawAmbiguousErrors(t *testing.T) {
+	dataDir := t.TempDir()
+	makeUserData(t, dataDir, testProfileDefault)
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "chrome", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("c")}},
+		{Browser: "edge", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("e")}},
+	}}
+	if _, err := BuildFromDump(dump, dataDir, ""); err == nil {
+		t.Fatal("expected ambiguity error for raw multi-vault restore without -b")
+	}
+}
+
+func TestBuildFromDump_MissingDataDirErrors(t *testing.T) {
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "chrome", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("c")}},
+	}}
+	if _, err := BuildFromDump(dump, "/no/such/dir", ""); err == nil {
+		t.Fatal("expected error when data dir does not exist")
+	}
+}
+
+// TestBuildFromDump_MarkerlessTreeStillResolves covers an archive/copy that omitted Preferences:
+// the source-bearing-subdir fallback in discoverProfiles must still find the profile.
+func TestBuildFromDump_MarkerlessTreeStillResolves(t *testing.T) {
+	dataDir := t.TempDir()
+	dir := filepath.Join(dataDir, "chrome", testProfileDefault)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "History"), []byte("x"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	dump := masterkey.Dump{Vaults: []masterkey.Vault{
+		{Browser: "chrome", Kind: "chromium", Keys: masterkey.MasterKeys{V10: []byte("c")}},
+	}}
+
+	browsers, err := BuildFromDump(dump, dataDir, "")
+	if err != nil {
+		t.Fatalf("BuildFromDump: %v", err)
+	}
+	if len(browsers) != 1 {
+		t.Fatalf("got %d browsers, want 1 (marker-less profile must resolve via source fallback)", len(browsers))
 	}
 }