Make an unlocker's ID the name of its directory (closes #98)

Keychain and Secure Enclave unlocker IDs were the creation time to the
minute plus the host name, and passphrase unlocker IDs the time to the
minute, so two created within one minute shared an ID, and `unlocker
select`, `unlocker remove` and the selection after `unlocker add` acted on
the older one. Every unlocker's ID is now its directory name, unique in
its vault. PGP unlocker IDs were `pgp-<fingerprint>`; the check that
refuses a second PGP unlocker for one key now compares the fingerprint in
the other unlockers' metadata.

Model: opus-5-5

internal/cli/unlockers_ids_test.go

@@ -0,0 +1,74 @@
+//nolint:testpackage // white-box test of unexported internals
+package cli
+
+import (
+	"encoding/json"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"git.eeqj.de/sneak/secret/internal/secret"
+	"git.eeqj.de/sneak/secret/internal/vault"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestSameMinuteUnlockersHaveTheirOwnIDs writes two passphrase unlockers
+// created in the same minute side by side, as an `unlocker add passphrase`
+// that fails before removing the old one leaves them, and asserts that
+// `unlocker list` gives each its own ID, and that each is selected and
+// removed by its ID alone. Keychain and Secure Enclave unlockers, which
+// only macOS can add, get their IDs the same way.
+func TestSameMinuteUnlockersHaveTheirOwnIDs(t *testing.T) {
+	t.Parallel()
+
+	fs := afero.NewMemMapFs()
+	_, err := vault.CreateVault(fs, listTestStateDir, listTestVaultName,
+		testMnemonicBuffer(t))
+	require.NoError(t, err)
+
+	vaultDir := testVaultDir(listTestVaultName)
+	unlockersDir := filepath.Join(vaultDir, listTestUnlockersDirName)
+	dirNames := []string{
+		"passphrase-2026-10-04.12.30.00.000000000",
+		"passphrase-2026-10-04.12.30.30.000000000",
+	}
+
+	for i, dirName := range dirNames {
+		metadata, err := json.Marshal(secret.UnlockerMetadata{
+			Type:      unlockerTypePassphrase,
+			CreatedAt: time.Date(2026, time.October, 4, 12, 30, 30*i, 0, time.UTC),
+		})
+		require.NoError(t, err)
+
+		dir := filepath.Join(unlockersDir, dirName)
+		require.NoError(t, fs.MkdirAll(dir, listTestDirPerm))
+		require.NoError(t, afero.WriteFile(fs,
+			filepath.Join(dir, listTestMetadataFileName), metadata,
+			listTestFilePerm))
+	}
+
+	listed := listUnlockersJSON(t, fs)
+	require.Len(t, listed, len(dirNames))
+
+	instance, cmd := newTestInstance(fs)
+
+	for i, unlocker := range listed {
+		assert.Equal(t, dirNames[i], unlocker.ID)
+
+		require.NoError(t, instance.UnlockerSelect(unlocker.ID))
+
+		current, err := afero.ReadFile(fs,
+			filepath.Join(vaultDir, "current-unlocker"))
+		require.NoError(t, err)
+		assert.Equal(t, dirNames[i], string(current))
+	}
+
+	// The newer one first: an ID both shared would remove the older one
+	require.NoError(t, instance.UnlockersRemove(listed[1].ID, true, cmd))
+	assertDirEntries(t, fs, unlockersDir, dirNames[0])
+
+	require.NoError(t, instance.UnlockersRemove(listed[0].ID, true, cmd))
+	assertDirEntries(t, fs, unlockersDir)
+}