Make another unlocker current when the current one is removed (closes #137)

Removing the vault's current unlocker left current-unlocker naming it,
so every command that opened the vault failed although another
unlocker remained, and the error pointed at the mnemonic.
RemoveUnlocker now makes the first other unlocker, in the order
`secret unlocker list` shows, current before the removal and returns
its ID, which `secret unlocker remove` prints; removing the last
unlocker also removes current-unlocker. When current-unlocker names an
unlocker that does not exist and the vault has others, the error wraps
ErrUnlockerNotFound and says to run `secret unlocker select`, without
the mnemonic advice.

Unverified: no test covers that advice for a vault other than the
current one, which gets `secret vault select` first.

Model: opus-5-5

README.md

@@ -241,6 +241,12 @@ 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, in
+the order `secret unlocker list` shows them, the current one, and says which;
+removing the last unlocker leaves the vault without a current unlocker. When
+`current-unlocker` names an unlocker that does not exist and the vault has
+others, opening the vault fails with an error that says to select one of them
+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 +18,18 @@ 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, in the order
+  `secret unlocker list` shows, current before removing it, and says so;
+  removing the last unlocker 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
+  others, the error wraps `vault.ErrUnlockerNotFound` and says to run
+  `secret unlocker select`, without the advice to use the mnemonic.
 - 2026-10-12: A mnemonic typed with extra spaces, tabs or line breaks gives the
   same long-term key as its words separated by single spaces
   (https://git.eeqj.de/sneak/secret/issues/135). The key was derived from the

internal/cli/unlock_failure_test.go

@@ -4,9 +4,10 @@
 // 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
-// missing, the error says how to make a version current again. Each test
-// that pins such advice also follows it.
+// passphrase could not be read at all. When the current unlocker does not
+// exist and the vault has another, the 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 +223,34 @@ 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"))
+}
+
 // 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 +222,10 @@ 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 ` +
-			`mnemonic, vault data will be permanently inaccessible.`,
+			`is given. Removing the current unlocker makes another of the ` +
+			`vault's unlockers current, if it has one. 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 +614,17 @@ 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 +1,68 @@
+//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/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, the vault's last,
+// removes current-unlocker.
+//
+//nolint:paralleltest // t.Setenv (GNUPGHOME) forbids parallel tests
+func TestUnlockerRemoveCurrent(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)
+
+	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 last 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"
 
@@ -52,6 +54,11 @@ 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),
@@ -119,6 +126,36 @@ 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 other unlockers.
+// When the vault 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
+	}
+
+	unlockers, err := v.ListUnlockers()
+	if err != nil {
+		return err
+	}
+
+	if len(unlockers) == 0 {
+		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
@@ -282,10 +319,16 @@ 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 vault's first
+// other unlocker in ID order, the order `secret unlocker list` shows, is
+// made current before the removal; with no other, 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 +337,73 @@ 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
-	return unlocker.Remove()
+	if err != nil {
+		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 vault's first unlocker in ID order other
+// than unlockerID the current unlocker and returns its ID. It returns ""
+// when the vault has no other unlocker.
+func (v *Vault) selectOtherUnlocker(unlockerID string) (string, error) {
+	unlockers, err := v.ListUnlockers()
+	if err != nil {
+		return "", err
+	}
+
+	for _, id := range slices.Sorted(maps.Keys(unlockers)) {
+		if id == unlockerID {
+			continue
+		}
+
+		err = v.SelectUnlocker(id)
+		if err != nil {
+			return "", err
+		}
+
+		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
 }