fix(keychain)!: return empty map from Filter on Linux when nothing matches

store/keychain/keychain_linux.go

@@ -689,10 +689,6 @@ func (k *keychainStore[T]) Filter(ctx context.Context, pattern store.Pattern) (m
 		return nil, fmt.Errorf("failed to search collection: %w", err)
 	}
 
-	if len(itemPaths) == 0 {
-		return nil, store.ErrCredentialNotFound
-	}
-
 	credentials := make(map[store.ID]store.Secret)
 	for _, itemPath := range itemPaths {
 		attributes, err := service.GetAttributes(itemPath)
@@ -728,9 +724,5 @@ func (k *keychainStore[T]) Filter(ctx context.Context, pattern store.Pattern) (m
 		credentials[secretID] = secret
 	}
 
-	if len(credentials) == 0 {
-		return nil, store.ErrCredentialNotFound
-	}
-
 	return credentials, nil
 }

store/keychain/keychain_linux_test.go

@@ -415,6 +415,32 @@ func TestKeychainFilterRetriesWhenCollectionRelocks(t *testing.T) {
 	assert.Equal(t, 2, fake.unlockCalls, "exactly one Unlock per relock retry")
 }
 
+func TestKeychainFilterEmpty(t *testing.T) {
+	fake := &fakeService{} // no items -> empty search
+	withFakeService(t, fake)
+
+	ks := setupKeychain(t, nil)
+	creds, err := ks.Filter(t.Context(), store.MustParsePattern("**"))
+	require.NoError(t, err)
+	assert.NotNil(t, creds)
+	assert.Empty(t, creds)
+}
+
+func TestKeychainFilterNoMatch(t *testing.T) {
+	fake := &fakeService{
+		items:      []dbus.ObjectPath{"/org/freedesktop/secrets/collection/login/1"},
+		attributes: kc.Attributes{"id": "com.test.test/test/bob"},
+	}
+	withFakeService(t, fake)
+
+	ks := setupKeychain(t, nil)
+	creds, err := ks.Filter(t.Context(), store.MustParsePattern("com.test.test/test/alice"))
+	require.NoError(t, err)
+	assert.NotNil(t, creds)
+	assert.Empty(t, creds)
+	assert.Equal(t, 0, fake.getSecretCalls, "non-matching item must not be loaded")
+}
+
 // The real-keychain dedup tests use their own service group/name so their items
 // are namespace-isolated from TestKeychain (which shares com.test.test/test).
 // GetAllMetadata/Filter search by {service:group, service:name}, so a leaked

store/store.go

@@ -93,6 +93,9 @@ type Store interface {
 	Upsert(ctx context.Context, id ID, secret Secret) error
 	// Filter returns a map of secrets based on a [Pattern].
 	//
+	// A pattern matching nothing is a valid empty result: implementations
+	// return an empty (non-nil) map with a nil error, not ErrCredentialNotFound.
+	//
 	// Secrets returned will have both [Secret.SetMetadata] and [Secret.Unmarshal]
 	// called; in that order. Any error produced by any of them would result in
 	// an early return with a nil secrets map.