README.md

@@ -241,6 +241,14 @@ that the vault then opens only with its mnemonic (see
 [Confirmation Before Removal](#confirmation-before-removal)). An unlocker
 directory that `secret unlocker list` skips with a warning, because its metadata
 cannot be read or parsed, is removed by the directory name the warning gives.
+Removing the current unlocker makes the first of the vault's other unlockers
+that `secret unlocker select` accepts, in the order `secret unlocker list` shows
+them, the current one, and says which; when there is none, the vault is left
+without a current unlocker. `secret unlocker select` refuses an unlocker whose
+type is not `passphrase` or `pgp`. When `current-unlocker` names an unlocker
+that does not exist and the vault has another that `secret unlocker select`
+accepts, opening the vault fails with an error that says to select one with
+`secret unlocker select`.
 
 - `--force, -f`: Remove without asking, even the last unlocker
 - **CRITICAL WARNING**: Without unlockers and without your mnemonic phrase,

TODO.md

@@ -18,6 +18,19 @@ https://git.eeqj.de/sneak/secret/milestone/12
 
 # Completed Steps
 
+- 2026-10-14: Removing the current unlocker no longer leaves the vault unable to
+  open through the unlockers it still has
+  (https://git.eeqj.de/sneak/secret/issues/137). `current-unlocker` went on
+  naming the removed unlocker, so every command that opened the vault failed,
+  with advice to use the mnemonic. `secret unlocker remove` of the current
+  unlocker now makes the first of the vault's other unlockers that
+  `secret unlocker select` accepts, in the order `secret unlocker list` shows,
+  current before removing it, and says so; when there is none, it also removes
+  `current-unlocker`. `vault.RemoveUnlocker` returns the ID of the unlocker it
+  made current. When `current-unlocker` names an unlocker that does not exist
+  and the vault has another that `secret unlocker select` accepts, the error
+  wraps `vault.ErrUnlockerNotFound` and says to run `secret unlocker select`,
+  without the advice to use the mnemonic.
 - 2026-10-14: A `secret add --force` that cannot unlock the vault, given a wrong
   passphrase or mnemonic, leaves the secret as it was
   (https://git.eeqj.de/sneak/secret/issues/136). The new version used to be

internal/cli/unlock_failure_test.go

@@ -4,9 +4,11 @@
 // file the unlocker needs is missing or the passphrase is wrong, the error
 // keeps its cause and ends by saying that the mnemonic still opens that
 // vault, but only for a vault that the mnemonic does open, and not when the
-// passphrase could not be read at all. When a secret's current file is
+// passphrase could not be read at all. When the current unlocker does not
-// missing, the error says how to make a version current again. Each test
+// exist and the vault has another that `secret unlocker select` accepts, the
-// that pins such advice also follows it.
+// error says to select one instead.
+// When a secret's current file is missing, the error says how to make a
+// version current again. Each test that pins such advice also follows it.
 
 package cli_test
 
@@ -222,6 +224,69 @@ func TestMoveUnlockFailureNamesVault(t *testing.T) {
 	assert.Equal(t, "value", getSecret(t, c, "y"))
 }
 
+// TestMissingCurrentUnlockerNamesSelect checks the error of `secret get`
+// when current-unlocker names an unlocker that does not exist and the vault
+// has another: it names the missing unlocker and says to select another
+// one, without the advice to use the mnemonic. The test then follows that
+// advice.
+func TestMissingCurrentUnlockerNamesSelect(t *testing.T) {
+	t.Parallel()
+
+	fs := newTwoVaultFs(t)
+	unlockerDir, c := newUnlockTestCLI(t, fs)
+
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(unlockTestVaultDir, "current-unlocker"),
+		[]byte("missing"), secret.FilePerms))
+
+	err := c.GetSecret(discardCmd(), "x")
+
+	require.ErrorIs(t, err, vault.ErrUnlockerNotFound)
+	require.EqualError(t, err, "failed to unlock vault: "+
+		"failed to get long-term key: failed to get current unlocker: "+
+		"unlocker with ID missing not found; the vault 'default' has other "+
+		"unlockers: run 'secret unlocker select' with the ID of one of them "+
+		"to make it the current unlocker")
+
+	require.NoError(t, c.UnlockerSelect(filepath.Base(unlockerDir)))
+	assert.Equal(t, "value", getSecret(t, c, "x"))
+}
+
+// TestMissingCurrentUnlockerNamesMnemonic checks the error of `secret get`
+// when the unlocker that current-unlocker names does not exist and the
+// vault's only other unlocker is the directory "odd", whose metadata names a
+// type that `secret unlocker select` refuses: the error ends with the advice
+// that the mnemonic still opens the vault, not with advice to select another
+// unlocker. The test then follows that advice.
+func TestMissingCurrentUnlockerNamesMnemonic(t *testing.T) {
+	t.Parallel()
+
+	fs := newTwoVaultFs(t)
+	unlockerDir, c := newUnlockTestCLI(t, fs)
+
+	require.NoError(t, fs.RemoveAll(unlockerDir))
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(unlockTestVaultDir, "unlockers.d", "odd",
+			"unlocker-metadata.json"),
+		[]byte(`{"type": "odd"}`), secret.FilePerms))
+
+	err := c.GetSecret(discardCmd(), "x")
+
+	var cause *os.PathError
+
+	require.ErrorAs(t, err, &cause)
+	require.NotErrorIs(t, err, vault.ErrUnlockerNotFound)
+	require.EqualError(t, err, "failed to unlock vault: "+
+		"failed to get long-term key: failed to get current unlocker: "+
+		"failed to read unlocker metadata: "+cause.Error()+mnemonicAdvice)
+
+	c.Mnemonic = testMnemonicBuffer(t)
+	require.NoError(t, c.UnlockersAdd("passphrase", discardCmd()))
+
+	c.Mnemonic = nil
+	assert.Equal(t, "value", getSecret(t, c, "x"))
+}
+
 // TestPassphraseNotReadNamesNoMnemonic runs `secret get x` on the built
 // binary without SB_UNLOCK_PASSPHRASE and with a stdin that is not a
 // terminal, so the passphrase cannot be read. The unlocker was not tried,

internal/cli/unlockers.go

@@ -222,8 +222,11 @@ func newUnlockerRemoveCmd() *cobra.Command {
 		Long: `Remove an unlocker from the current vault. Asks for ` +
 			`confirmation first, saying whether it is the vault's last ` +
 			`unlocker; when stdin is not a terminal, fails unless --force ` +
-			`is given. Warning: Without unlockers and without your ` +
+			`is given. Removing the current unlocker makes another of the ` +
-			`mnemonic, vault data will be permanently inaccessible.`,
+			`vault's unlockers current, if it has one that ` +
+			`'secret unlocker select' accepts. Warning: Without ` +
+			`unlockers and without your mnemonic, vault data will be ` +
+			`permanently inaccessible.`,
 		Args:              cobra.ExactArgs(1),
 		ValidArgsFunction: getUnlockerIDsCompletionFunc(cli.fs, cli.stateDir),
 		RunE: func(cmd *cobra.Command, args []string) error {
@@ -612,13 +615,17 @@ func (cli *Instance) removeUnlocker(
 			"have your mnemonic phrase to access this vault again!")
 	}
 
-	err := found.vlt.RemoveUnlocker(unlockerID)
+	newCurrentID, err := found.vlt.RemoveUnlocker(unlockerID)
 	if err != nil {
 		return err
 	}
 
 	cmd.Printf("Removed unlocker '%s'\n", unlockerID)
 
+	if newCurrentID != "" {
+		cmd.Printf("Switched current unlocker to '%s'\n", newCurrentID)
+	}
+
 	return nil
 }
 

internal/cli/unlockers_remove_test.go

@@ -0,0 +1,94 @@
+//nolint:testpackage // white-box test of unexported internals
+package cli
+
+import (
+	"bytes"
+	"path/filepath"
+	"testing"
+
+	"github.com/awnumar/memguard"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/secret/internal/secret"
+	"sneak.berlin/go/secret/internal/vault"
+)
+
+// TestUnlockerRemoveCurrent is a regression test for
+// https://git.eeqj.de/sneak/secret/issues/137. A vault has a passphrase
+// unlocker and a PGP unlocker, the current one. Removing the PGP unlocker
+// makes the passphrase unlocker current and says so, and the vault then
+// opens through it. Removing the passphrase unlocker too removes
+// current-unlocker.
+//
+// The second case also gives the vault the unlocker directory "odd", whose
+// metadata names a type that `secret unlocker select` refuses, and which
+// sorts before the passphrase unlocker: neither removal makes it current.
+//
+//nolint:paralleltest // t.Setenv (GNUPGHOME) forbids parallel tests
+func TestUnlockerRemoveCurrent(t *testing.T) {
+	tests := []struct {
+		name    string
+		withOdd bool
+	}{
+		{name: "two unlockers", withOdd: false},
+		{name: "and the directory odd", withOdd: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			newTestGPGKey(t)
+
+			passphrase := memguard.NewBufferFromBytes([]byte(testPassphrase))
+			t.Cleanup(passphrase.Destroy)
+
+			fs := afero.NewMemMapFs()
+			vlt, err := vault.CreateVault(fs, listTestStateDir,
+				listTestVaultName, testMnemonicBuffer(t), nil)
+			require.NoError(t, err)
+
+			passphraseUnlocker, err := vlt.CreatePassphraseUnlocker(passphrase)
+			require.NoError(t, err)
+
+			if tt.withOdd {
+				require.NoError(t, afero.WriteFile(fs,
+					filepath.Join(testVaultDir(listTestVaultName), "unlockers.d",
+						"odd", "unlocker-metadata.json"),
+					[]byte(`{"type": "odd"}`), secret.FilePerms))
+			}
+
+			instance, cmd := newTestInstance(fs)
+			instance.UnlockPassphrase = passphrase
+
+			cmd.Flags().String("keyid", unreadableTestGPGUserID, "")
+			require.NoError(t, instance.UnlockersAdd(unlockerTypePGP, cmd))
+
+			pgpUnlocker, err := vlt.GetCurrentUnlocker()
+			require.NoError(t, err)
+			require.Equal(t, unlockerTypePGP, pgpUnlocker.GetType())
+
+			var output bytes.Buffer
+
+			cmd.SetOut(&output)
+			require.NoError(t,
+				instance.UnlockersRemove(pgpUnlocker.GetID(), true, cmd))
+			assert.Contains(t, output.String(),
+				"Switched current unlocker to '"+passphraseUnlocker.GetID()+"'")
+
+			reopened := vault.NewVault(fs, listTestStateDir, listTestVaultName)
+			reopened.UnlockPassphrase = passphrase
+
+			_, err = reopened.GetOrDeriveLongTermKey()
+			require.NoError(t, err)
+
+			require.NoError(t,
+				instance.UnlockersRemove(passphraseUnlocker.GetID(), true, cmd))
+
+			exists, err := afero.Exists(fs, filepath.Join(
+				testVaultDir(listTestVaultName), "current-unlocker"))
+			require.NoError(t, err)
+			assert.False(t, exists,
+				"current-unlocker is left after the passphrase unlocker")
+		})
+	}
+}

internal/vault/errors_test.go

@@ -81,7 +81,9 @@ func TestVaultErrors(t *testing.T) {
 			return vlt.CopySecretAllVersions(vlt, versionless, "copy", false)
 		}, vault.ErrNoVersions},
 		{"remove a missing unlocker", func(vlt *vault.Vault) error {
-			return vlt.RemoveUnlocker(missingName)
+			_, err := vlt.RemoveUnlocker(missingName)
+
+			return err
 		}, vault.ErrUnlockerNotFound},
 		{"select a missing unlocker", func(vlt *vault.Vault) error {
 			return vlt.SelectUnlocker(missingName)

internal/vault/unlockers.go

@@ -5,8 +5,10 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"maps"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 	"time"
 
@@ -19,6 +21,7 @@ import (
 // Unlocker metadata type strings.
 const (
 	unlockerTypePassphrase = "passphrase"
+	unlockerTypePGP        = "pgp"
 )
 
 // GetCurrentUnlocker returns the current unlocker for this vault
@@ -52,6 +55,11 @@ func (v *Vault) GetCurrentUnlocker() (secret.Unlocker, error) {
 		return nil, err
 	}
 
+	err = v.checkCurrentUnlockerExists(unlockerDir)
+	if err != nil {
+		return nil, err
+	}
+
 	secret.DebugWith("Resolved unlocker directory",
 		slog.String("unlocker_dir", unlockerDir),
 		slog.String("vault_name", v.Name),
@@ -74,7 +82,7 @@ func (v *Vault) GetCurrentUnlocker() (secret.Unlocker, error) {
 		passphraseUnlocker := secret.NewPassphraseUnlocker(v.fs, unlockerDir, metadata)
 		passphraseUnlocker.Passphrase = v.UnlockPassphrase
 		unlocker = passphraseUnlocker
-	case "pgp":
+	case unlockerTypePGP:
 		secret.Debug("Creating PGP unlocker instance", "unlocker_type", metadata.Type)
 
 		unlocker = secret.NewPGPUnlocker(v.fs, unlockerDir, metadata)
@@ -119,6 +127,37 @@ func (v *Vault) resolveUnlockerDirectory(currentUnlockerPath string) (string, er
 	return absolutePath, nil
 }
 
+// checkCurrentUnlockerExists fails with ErrUnlockerNotFound, saying to
+// select another unlocker, when unlockerDir, the unlocker directory that
+// current-unlocker names, does not exist and the vault has another unlocker
+// that SelectUnlocker accepts. When it has none, it returns nil: reading the
+// missing unlocker then fails, with the advice that the mnemonic still opens
+// the vault.
+func (v *Vault) checkCurrentUnlockerExists(unlockerDir string) error {
+	exists, err := afero.DirExists(v.fs, unlockerDir)
+	if err != nil {
+		return fmt.Errorf("failed to check for the current unlocker: %w", err)
+	}
+
+	if exists {
+		return nil
+	}
+
+	otherID, err := v.firstOtherUnlockerID(filepath.Base(unlockerDir))
+	if err != nil {
+		return err
+	}
+
+	if otherID == "" {
+		return nil
+	}
+
+	return fmt.Errorf("unlocker with ID %s %w; the vault '%s' has other "+
+		"unlockers: run %s with the ID of one of them to make it the current "+
+		"unlocker", filepath.Base(unlockerDir), ErrUnlockerNotFound, v.Name,
+		v.withVaultSelect("'secret unlocker select'"))
+}
+
 // findUnlockerByID finds an unlocker by its ID and returns the unlocker
 // instance and its directory path. A directory that ListUnlockers skips is
 // skipped here too, with the same warning. Such a directory has no ID: if
@@ -159,7 +198,7 @@ func (v *Vault) findUnlockerByID(
 		switch metadata.Type {
 		case unlockerTypePassphrase:
 			tempUnlocker = secret.NewPassphraseUnlocker(v.fs, unlockerDirPath, metadata)
-		case "pgp":
+		case unlockerTypePGP:
 			tempUnlocker = secret.NewPGPUnlocker(v.fs, unlockerDirPath, metadata)
 		default:
 			continue
@@ -282,10 +321,15 @@ func (v *Vault) HasUnlocker(unlockerID string) (bool, error) {
 // RemoveUnlocker removes an unlocker from this vault. An unlocker
 // directory that ListUnlockers skips is removed by its directory name; its
 // type is unknown, so only the directory is removed.
-func (v *Vault) RemoveUnlocker(unlockerID string) error {
+//
+// It returns the ID of the unlocker it made current, or "" when it made none
+// current. If the removed unlocker is the current one, the unlocker
+// firstOtherUnlockerID returns is made current before the removal; with
+// none, current-unlocker is removed after it.
+func (v *Vault) RemoveUnlocker(unlockerID string) (string, error) {
 	vaultDir, err := v.GetDirectory()
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	// Find the unlocker directory and create the unlocker instance
@@ -294,19 +338,92 @@ func (v *Vault) RemoveUnlocker(unlockerID string) error {
 	// Find the unlocker by ID
 	unlocker, unlockerDir, err := v.findUnlockerByID(unlockersDir, unlockerID)
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	if unlockerDir == "" {
-		return fmt.Errorf("unlocker with ID %s %w", unlockerID, ErrUnlockerNotFound)
+		return "", fmt.Errorf("unlocker with ID %s %w", unlockerID, ErrUnlockerNotFound)
+	}
+
+	currentUnlockerPath := filepath.Join(vaultDir, "current-unlocker")
+
+	currentDir, err := v.resolveUnlockerDirectory(currentUnlockerPath)
+	if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return "", err
+	}
+
+	isCurrent := currentDir == unlockerDir
+	newCurrentID := ""
+
+	if isCurrent {
+		newCurrentID, err = v.selectOtherUnlocker(unlockerID)
+		if err != nil {
+			return "", err
+		}
 	}
 
 	if unlocker == nil {
-		return secret.RemoveDirAtomic(v.fs, unlockerDir)
+		err = secret.RemoveDirAtomic(v.fs, unlockerDir)
+	} else {
+		err = unlocker.Remove()
 	}
 
-	// Use the unlocker's Remove method
+	if err != nil {
-	return unlocker.Remove()
+		return "", err
+	}
+
+	if isCurrent && newCurrentID == "" {
+		err = v.fs.Remove(currentUnlockerPath)
+		if err != nil {
+			return "", fmt.Errorf("failed to remove current-unlocker file: %w", err)
+		}
+	}
+
+	return newCurrentID, nil
+}
+
+// selectOtherUnlocker makes the unlocker firstOtherUnlockerID returns for
+// unlockerID the current unlocker and returns its ID. It returns "" when
+// there is no such unlocker.
+func (v *Vault) selectOtherUnlocker(unlockerID string) (string, error) {
+	otherID, err := v.firstOtherUnlockerID(unlockerID)
+	if err != nil {
+		return "", err
+	}
+
+	if otherID == "" {
+		return "", nil
+	}
+
+	err = v.SelectUnlocker(otherID)
+	if err != nil {
+		return "", err
+	}
+
+	return otherID, nil
+}
+
+// firstOtherUnlockerID returns the ID of the vault's first unlocker other
+// than unlockerID, in ID order, the order `secret unlocker list` shows, that
+// SelectUnlocker accepts, or "" when there is none. SelectUnlocker refuses
+// an unlocker whose metadata names a type other than passphrase or pgp,
+// which ListUnlockers still returns.
+func (v *Vault) firstOtherUnlockerID(unlockerID string) (string, error) {
+	unlockers, err := v.ListUnlockers()
+	if err != nil {
+		return "", err
+	}
+
+	for _, id := range slices.Sorted(maps.Keys(unlockers)) {
+		unlockerType := unlockers[id].Type
+
+		if id != unlockerID && (unlockerType == unlockerTypePassphrase ||
+			unlockerType == unlockerTypePGP) {
+			return id, nil
+		}
+	}
+
+	return "", nil
 }
 
 // SelectUnlocker selects an unlocker as current for this vault

internal/vault/vault.go

@@ -291,9 +291,11 @@ func (v *Vault) unlockLongTermKey(
 // without a mnemonic records none, and without its metadata the key cannot
 // be derived. It is not added when the passphrase could not be read: the
 // unlocker was not tried, and adding one would need a passphrase read the
-// same way.
+// same way. Nor is it added when the current unlocker does not exist and the
+// vault has others: the error already says to select one of them.
 func (v *Vault) withMnemonicAdvice(err error) error {
-	if errors.Is(err, secret.ErrPassphraseNotRead) {
+	if errors.Is(err, secret.ErrPassphraseNotRead) ||
+		errors.Is(err, ErrUnlockerNotFound) {
 		return err
 	}
 
@@ -304,15 +306,21 @@ func (v *Vault) withMnemonicAdvice(err error) error {
 		return err
 	}
 
-	// 'secret unlocker add' acts on the current vault only.
-	steps := "'secret unlocker add passphrase'"
-
-	current, currentErr := GetCurrentVault(v.fs, v.stateDir)
-	if currentErr != nil || current.Name != v.Name {
-		steps = fmt.Sprintf("'secret vault select %s', then %s", v.Name, steps)
-	}
-
 	return fmt.Errorf("%w; the vault '%s' still opens with its mnemonic: run "+
 		"%s with %s set to the mnemonic to give it a new unlocker",
-		err, v.Name, steps, secret.EnvMnemonic)
+		err, v.Name, v.withVaultSelect("'secret unlocker add passphrase'"),
+		secret.EnvMnemonic)
+}
+
+// withVaultSelect returns command, a quoted 'secret unlocker' command, for
+// advice about this vault. Such a command acts on the current vault only,
+// so when this vault is not the current one, the command that selects it
+// comes first.
+func (v *Vault) withVaultSelect(command string) string {
+	current, err := GetCurrentVault(v.fs, v.stateDir)
+	if err != nil || current.Name != v.Name {
+		return fmt.Sprintf("'secret vault select %s', then %s", v.Name, command)
+	}
+
+	return command
 }