[feature] Implement Filter API v2 (#2936)

* Use correct entity name

* We support server-side filters now

* Document filter v1 methods that can throw a 409

* Validate v1 filter phrase as filter title

* Always check v1 filter API status codes in tests

* Document keyword minimum requirement on filter API v1

* Make it possible to specify filter keyword update columns per filter keyword

* Implement v2 filter API

* Fix lint and tests

* Update Swagger spec

* Fix filter update test

* Update Swagger spec *correctly*

* Update actual files Swagger spec was generated from

* Remove keywords_attributes and statuses_attributes

* Add test for serialization of empty filter

* More helpful messages when object is owned by wrong account

15 files changed, 897 insertions, 5 deletions

diff --git a/internal/processing/filters/v1/get.go b/internal/processing/filters/v1/get.go
index 39575dd94..3ead09b20 100644
--- a/internal/processing/filters/v1/get.go
+++ b/internal/processing/filters/v1/get.go
@@ -59,8 +59,8 @@ func (p *Processor) GetAll(ctx context.Context, account *gtsmodel.Account) ([]*a
 	}
 
 	apiFilters := make([]*apimodel.FilterV1, 0, len(filters))
-	for _, list := range filters {
-		apiFilter, errWithCode := p.apiFilter(ctx, list)
+	for _, filter := range filters {
+		apiFilter, errWithCode := p.apiFilter(ctx, filter)
 		if errWithCode != nil {
 			return nil, errWithCode
 		}
diff --git a/internal/processing/filters/v1/update.go b/internal/processing/filters/v1/update.go
index 1fe49721b..0421dc786 100644
--- a/internal/processing/filters/v1/update.go
+++ b/internal/processing/filters/v1/update.go
@@ -149,9 +149,11 @@ func (p *Processor) Update(
 		"context_thread",
 		"context_account",
 	}
-	filterKeywordColumns := []string{
-		"keyword",
-		"whole_word",
+	filterKeywordColumns := [][]string{
+		{
+			"keyword",
+			"whole_word",
+		},
 	}
 	if err := p.state.DB.UpdateFilter(ctx, filter, filterColumns, filterKeywordColumns, nil, nil); err != nil {
 		if errors.Is(err, db.ErrAlreadyExists) {
diff --git a/internal/processing/filters/v2/convert.go b/internal/processing/filters/v2/convert.go
new file mode 100644
index 000000000..1e544e6e4
--- /dev/null
+++ b/internal/processing/filters/v2/convert.go
@@ -0,0 +1,38 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"fmt"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// apiFilter is a shortcut to return the API v2 filter version of the given
+// filter, or return an appropriate error if conversion fails.
+func (p *Processor) apiFilter(ctx context.Context, filterKeyword *gtsmodel.Filter) (*apimodel.FilterV2, gtserror.WithCode) {
+	apiFilter, err := p.converter.FilterToAPIFilterV2(ctx, filterKeyword)
+	if err != nil {
+		return nil, gtserror.NewErrorInternalError(fmt.Errorf("error converting filter to API v2 filter: %w", err))
+	}
+
+	return apiFilter, nil
+}
diff --git a/internal/processing/filters/v2/create.go b/internal/processing/filters/v2/create.go
new file mode 100644
index 000000000..c7b500e9e
--- /dev/null
+++ b/internal/processing/filters/v2/create.go
@@ -0,0 +1,75 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// Create a new filter for the given account, using the provided parameters.
+// These params should have already been validated by the time they reach this function.
+func (p *Processor) Create(ctx context.Context, account *gtsmodel.Account, form *apimodel.FilterCreateRequestV2) (*apimodel.FilterV2, gtserror.WithCode) {
+	filter := &gtsmodel.Filter{
+		ID:        id.NewULID(),
+		AccountID: account.ID,
+		Title:     form.Title,
+		Action:    typeutils.APIFilterActionToFilterAction(*form.FilterAction),
+	}
+	if form.ExpiresIn != nil {
+		filter.ExpiresAt = time.Now().Add(time.Second * time.Duration(*form.ExpiresIn))
+	}
+	for _, context := range form.Context {
+		switch context {
+		case apimodel.FilterContextHome:
+			filter.ContextHome = util.Ptr(true)
+		case apimodel.FilterContextNotifications:
+			filter.ContextNotifications = util.Ptr(true)
+		case apimodel.FilterContextPublic:
+			filter.ContextPublic = util.Ptr(true)
+		case apimodel.FilterContextThread:
+			filter.ContextThread = util.Ptr(true)
+		case apimodel.FilterContextAccount:
+			filter.ContextAccount = util.Ptr(true)
+		default:
+			return nil, gtserror.NewErrorUnprocessableEntity(
+				fmt.Errorf("unsupported filter context '%s'", context),
+			)
+		}
+	}
+
+	if err := p.state.DB.PutFilter(ctx, filter); err != nil {
+		if errors.Is(err, db.ErrAlreadyExists) {
+			err = errors.New("duplicate title, keyword, or status")
+			return nil, gtserror.NewErrorConflict(err, err.Error())
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return p.apiFilter(ctx, filter)
+}
diff --git a/internal/processing/filters/v2/delete.go b/internal/processing/filters/v2/delete.go
new file mode 100644
index 000000000..b1bebdcb6
--- /dev/null
+++ b/internal/processing/filters/v2/delete.go
@@ -0,0 +1,53 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// Delete an existing filter and all its attached keywords and statuses for the given account.
+func (p *Processor) Delete(
+	ctx context.Context,
+	account *gtsmodel.Account,
+	filterID string,
+) gtserror.WithCode {
+	// Get the filter for this keyword.
+	filter, err := p.state.DB.GetFilterByID(ctx, filterID)
+	if err != nil {
+		return gtserror.NewErrorNotFound(err)
+	}
+
+	// Check that the account owns it.
+	if filter.AccountID != account.ID {
+		return gtserror.NewErrorNotFound(
+			fmt.Errorf("filter %s doesn't belong to account %s", filter.ID, account.ID),
+		)
+	}
+
+	// Delete the entire filter.
+	if err := p.state.DB.DeleteFilterByID(ctx, filter.ID); err != nil {
+		return gtserror.NewErrorInternalError(err)
+	}
+
+	return nil
+}
diff --git a/internal/processing/filters/v2/filters.go b/internal/processing/filters/v2/filters.go
new file mode 100644
index 000000000..dfb6a8992
--- /dev/null
+++ b/internal/processing/filters/v2/filters.go
@@ -0,0 +1,35 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"github.com/superseriousbusiness/gotosocial/internal/state"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+)
+
+type Processor struct {
+	state     *state.State
+	converter *typeutils.Converter
+}
+
+func New(state *state.State, converter *typeutils.Converter) Processor {
+	return Processor{
+		state:     state,
+		converter: converter,
+	}
+}
diff --git a/internal/processing/filters/v2/get.go b/internal/processing/filters/v2/get.go
new file mode 100644
index 000000000..39b937eb2
--- /dev/null
+++ b/internal/processing/filters/v2/get.go
@@ -0,0 +1,81 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"slices"
+	"strings"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// Get looks up a filter by ID and returns it with keywords and statuses.
+func (p *Processor) Get(ctx context.Context, account *gtsmodel.Account, filterID string) (*apimodel.FilterV2, gtserror.WithCode) {
+	filter, err := p.state.DB.GetFilterByID(ctx, filterID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filter.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter %s doesn't belong to account %s", filter.ID, account.ID),
+		)
+	}
+
+	return p.apiFilter(ctx, filter)
+}
+
+// GetAll looks up all filters for the current account and returns them with keywords and statuses.
+func (p *Processor) GetAll(ctx context.Context, account *gtsmodel.Account) ([]*apimodel.FilterV2, gtserror.WithCode) {
+	filters, err := p.state.DB.GetFiltersForAccountID(
+		ctx,
+		account.ID,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, nil
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	apiFilters := make([]*apimodel.FilterV2, 0, len(filters))
+	for _, filter := range filters {
+		apiFilter, errWithCode := p.apiFilter(ctx, filter)
+		if errWithCode != nil {
+			return nil, errWithCode
+		}
+
+		apiFilters = append(apiFilters, apiFilter)
+	}
+
+	// Sort them by ID so that they're in a stable order.
+	// Clients may opt to sort them lexically in a locale-aware manner.
+	slices.SortFunc(apiFilters, func(lhs *apimodel.FilterV2, rhs *apimodel.FilterV2) int {
+		return strings.Compare(lhs.ID, rhs.ID)
+	})
+
+	return apiFilters, nil
+}
diff --git a/internal/processing/filters/v2/keywordcreate.go b/internal/processing/filters/v2/keywordcreate.go
new file mode 100644
index 000000000..711b855fa
--- /dev/null
+++ b/internal/processing/filters/v2/keywordcreate.go
@@ -0,0 +1,67 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+)
+
+// KeywordCreate adds a filter keyword to an existing filter for the given account, using the provided parameters.
+// These params should have already been normalized and validated by the time they reach this function.
+func (p *Processor) KeywordCreate(ctx context.Context, account *gtsmodel.Account, filterID string, form *apimodel.FilterKeywordCreateUpdateRequest) (*apimodel.FilterKeyword, gtserror.WithCode) {
+	// Check that the filter is owned by the given account.
+	filter, err := p.state.DB.GetFilterByID(gtscontext.SetBarebones(ctx), filterID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filter.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter %s doesn't belong to account %s", filter.ID, account.ID),
+		)
+	}
+
+	filterKeyword := &gtsmodel.FilterKeyword{
+		ID:        id.NewULID(),
+		AccountID: account.ID,
+		FilterID:  filter.ID,
+		Keyword:   form.Keyword,
+		WholeWord: form.WholeWord,
+	}
+
+	if err := p.state.DB.PutFilterKeyword(ctx, filterKeyword); err != nil {
+		if errors.Is(err, db.ErrAlreadyExists) {
+			err = errors.New("duplicate keyword")
+			return nil, gtserror.NewErrorConflict(err, err.Error())
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return p.converter.FilterKeywordToAPIFilterKeyword(ctx, filterKeyword), nil
+}
diff --git a/internal/processing/filters/v2/keyworddelete.go b/internal/processing/filters/v2/keyworddelete.go
new file mode 100644
index 000000000..edf57167d
--- /dev/null
+++ b/internal/processing/filters/v2/keyworddelete.go
@@ -0,0 +1,53 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// KeywordDelete deletes an existing filter keyword from a filter.
+func (p *Processor) KeywordDelete(
+	ctx context.Context,
+	account *gtsmodel.Account,
+	filterID string,
+) gtserror.WithCode {
+	// Get the filter keyword.
+	filterKeyword, err := p.state.DB.GetFilterKeywordByID(ctx, filterID)
+	if err != nil {
+		return gtserror.NewErrorNotFound(err)
+	}
+
+	// Check that the account owns it.
+	if filterKeyword.AccountID != account.ID {
+		return gtserror.NewErrorNotFound(
+			fmt.Errorf("filter keyword %s doesn't belong to account %s", filterKeyword.ID, account.ID),
+		)
+	}
+
+	// Delete the filter keyword.
+	if err := p.state.DB.DeleteFilterKeywordByID(ctx, filterKeyword.ID); err != nil {
+		return gtserror.NewErrorInternalError(err)
+	}
+
+	return nil
+}
diff --git a/internal/processing/filters/v2/keywordget.go b/internal/processing/filters/v2/keywordget.go
new file mode 100644
index 000000000..5f5a63b26
--- /dev/null
+++ b/internal/processing/filters/v2/keywordget.go
@@ -0,0 +1,89 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"slices"
+	"strings"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// KeywordGet looks up a filter keyword by ID.
+func (p *Processor) KeywordGet(ctx context.Context, account *gtsmodel.Account, filterKeywordID string) (*apimodel.FilterKeyword, gtserror.WithCode) {
+	filterKeyword, err := p.state.DB.GetFilterKeywordByID(ctx, filterKeywordID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filterKeyword.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter keyword %s doesn't belong to account %s", filterKeyword.ID, account.ID),
+		)
+	}
+
+	return p.converter.FilterKeywordToAPIFilterKeyword(ctx, filterKeyword), nil
+}
+
+// KeywordsGetForFilterID looks up all filter keywords for the given filter.
+func (p *Processor) KeywordsGetForFilterID(ctx context.Context, account *gtsmodel.Account, filterID string) ([]*apimodel.FilterKeyword, gtserror.WithCode) {
+	// Check that the filter is owned by the given account.
+	filter, err := p.state.DB.GetFilterByID(gtscontext.SetBarebones(ctx), filterID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filter.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(nil)
+	}
+
+	filterKeywords, err := p.state.DB.GetFilterKeywordsForFilterID(
+		ctx,
+		filter.ID,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, nil
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	apiFilterKeywords := make([]*apimodel.FilterKeyword, 0, len(filterKeywords))
+	for _, filterKeyword := range filterKeywords {
+		apiFilterKeywords = append(apiFilterKeywords, p.converter.FilterKeywordToAPIFilterKeyword(ctx, filterKeyword))
+	}
+
+	// Sort them by ID so that they're in a stable order.
+	// Clients may opt to sort them lexically in a locale-aware manner.
+	slices.SortFunc(apiFilterKeywords, func(lhs *apimodel.FilterKeyword, rhs *apimodel.FilterKeyword) int {
+		return strings.Compare(lhs.ID, rhs.ID)
+	})
+
+	return apiFilterKeywords, nil
+}
diff --git a/internal/processing/filters/v2/keywordupdate.go b/internal/processing/filters/v2/keywordupdate.go
new file mode 100644
index 000000000..9a4058c23
--- /dev/null
+++ b/internal/processing/filters/v2/keywordupdate.go
@@ -0,0 +1,66 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// KeywordUpdate updates an existing filter keyword for the given account, using the provided parameters.
+// These params should have already been validated by the time they reach this function.
+func (p *Processor) KeywordUpdate(
+	ctx context.Context,
+	account *gtsmodel.Account,
+	filterKeywordID string,
+	form *apimodel.FilterKeywordCreateUpdateRequest,
+) (*apimodel.FilterKeyword, gtserror.WithCode) {
+	// Get the filter keyword by ID.
+	filterKeyword, err := p.state.DB.GetFilterKeywordByID(gtscontext.SetBarebones(ctx), filterKeywordID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filterKeyword.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter keyword %s doesn't belong to account %s", filterKeyword.ID, account.ID),
+		)
+	}
+
+	filterKeyword.Keyword = form.Keyword
+	filterKeyword.WholeWord = form.WholeWord
+
+	if err := p.state.DB.UpdateFilterKeyword(ctx, filterKeyword, "keyword", "whole_word"); err != nil {
+		if errors.Is(err, db.ErrAlreadyExists) {
+			err = errors.New("duplicate keyword")
+			return nil, gtserror.NewErrorConflict(err, err.Error())
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return p.converter.FilterKeywordToAPIFilterKeyword(ctx, filterKeyword), nil
+}
diff --git a/internal/processing/filters/v2/statuscreate.go b/internal/processing/filters/v2/statuscreate.go
new file mode 100644
index 000000000..a211dec2e
--- /dev/null
+++ b/internal/processing/filters/v2/statuscreate.go
@@ -0,0 +1,66 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+)
+
+// StatusCreate adds a filter status to an existing filter for the given account, using the provided parameters.
+// These params should have already been validated by the time they reach this function.
+func (p *Processor) StatusCreate(ctx context.Context, account *gtsmodel.Account, filterID string, form *apimodel.FilterStatusCreateRequest) (*apimodel.FilterStatus, gtserror.WithCode) {
+	// Check that the filter is owned by the given account.
+	filter, err := p.state.DB.GetFilterByID(gtscontext.SetBarebones(ctx), filterID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filter.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter %s doesn't belong to account %s", filter.ID, account.ID),
+		)
+	}
+
+	filterStatus := &gtsmodel.FilterStatus{
+		ID:        id.NewULID(),
+		AccountID: account.ID,
+		FilterID:  filter.ID,
+		StatusID:  form.StatusID,
+	}
+
+	if err := p.state.DB.PutFilterStatus(ctx, filterStatus); err != nil {
+		if errors.Is(err, db.ErrAlreadyExists) {
+			err = errors.New("duplicate status")
+			return nil, gtserror.NewErrorConflict(err, err.Error())
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return p.converter.FilterStatusToAPIFilterStatus(ctx, filterStatus), nil
+}
diff --git a/internal/processing/filters/v2/statusdelete.go b/internal/processing/filters/v2/statusdelete.go
new file mode 100644
index 000000000..a428e7409
--- /dev/null
+++ b/internal/processing/filters/v2/statusdelete.go
@@ -0,0 +1,53 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// StatusDelete deletes an existing filter status from a filter.
+func (p *Processor) StatusDelete(
+	ctx context.Context,
+	account *gtsmodel.Account,
+	filterID string,
+) gtserror.WithCode {
+	// Get the filter status.
+	filterStatus, err := p.state.DB.GetFilterStatusByID(ctx, filterID)
+	if err != nil {
+		return gtserror.NewErrorNotFound(err)
+	}
+
+	// Check that the account owns it.
+	if filterStatus.AccountID != account.ID {
+		return gtserror.NewErrorNotFound(
+			fmt.Errorf("filter status %s doesn't belong to account %s", filterStatus.ID, account.ID),
+		)
+	}
+
+	// Delete the filter status.
+	if err := p.state.DB.DeleteFilterStatusByID(ctx, filterStatus.ID); err != nil {
+		return gtserror.NewErrorInternalError(err)
+	}
+
+	return nil
+}
diff --git a/internal/processing/filters/v2/statusget.go b/internal/processing/filters/v2/statusget.go
new file mode 100644
index 000000000..197a3872e
--- /dev/null
+++ b/internal/processing/filters/v2/statusget.go
@@ -0,0 +1,89 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"slices"
+	"strings"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// StatusGet looks up a filter status by ID.
+func (p *Processor) StatusGet(ctx context.Context, account *gtsmodel.Account, filterStatusID string) (*apimodel.FilterStatus, gtserror.WithCode) {
+	filterStatus, err := p.state.DB.GetFilterStatusByID(ctx, filterStatusID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filterStatus.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter status %s doesn't belong to account %s", filterStatus.ID, account.ID),
+		)
+	}
+
+	return p.converter.FilterStatusToAPIFilterStatus(ctx, filterStatus), nil
+}
+
+// StatusesGetForFilterID looks up all filter statuses for the given filter.
+func (p *Processor) StatusesGetForFilterID(ctx context.Context, account *gtsmodel.Account, filterID string) ([]*apimodel.FilterStatus, gtserror.WithCode) {
+	// Check that the filter is owned by the given account.
+	filter, err := p.state.DB.GetFilterByID(gtscontext.SetBarebones(ctx), filterID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filter.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(nil)
+	}
+
+	filterStatuses, err := p.state.DB.GetFilterStatusesForFilterID(
+		ctx,
+		filter.ID,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, nil
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	apiFilterStatuses := make([]*apimodel.FilterStatus, 0, len(filterStatuses))
+	for _, filterStatus := range filterStatuses {
+		apiFilterStatuses = append(apiFilterStatuses, p.converter.FilterStatusToAPIFilterStatus(ctx, filterStatus))
+	}
+
+	// Sort them by ID so that they're in a stable order.
+	// Clients may opt to sort them by status ID instead.
+	slices.SortFunc(apiFilterStatuses, func(lhs *apimodel.FilterStatus, rhs *apimodel.FilterStatus) int {
+		return strings.Compare(lhs.ID, rhs.ID)
+	})
+
+	return apiFilterStatuses, nil
+}
diff --git a/internal/processing/filters/v2/update.go b/internal/processing/filters/v2/update.go
new file mode 100644
index 000000000..aecb53337
--- /dev/null
+++ b/internal/processing/filters/v2/update.go
@@ -0,0 +1,125 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package v2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// Update an existing filter for the given account, using the provided parameters.
+// These params should have already been validated by the time they reach this function.
+func (p *Processor) Update(
+	ctx context.Context,
+	account *gtsmodel.Account,
+	filterID string,
+	form *apimodel.FilterUpdateRequestV2,
+) (*apimodel.FilterV2, gtserror.WithCode) {
+	// Get the filter by ID, with existing keywords and statuses.
+	filter, err := p.state.DB.GetFilterByID(ctx, filterID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if filter.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(
+			fmt.Errorf("filter %s doesn't belong to account %s", filter.ID, account.ID),
+		)
+	}
+
+	// Filter columns that we're going to update.
+	filterColumns := []string{}
+
+	// Apply filter changes.
+	if form.Title != nil {
+		filterColumns = append(filterColumns, "title")
+		filter.Title = *form.Title
+	}
+	if form.FilterAction != nil {
+		filterColumns = append(filterColumns, "action")
+		filter.Action = typeutils.APIFilterActionToFilterAction(*form.FilterAction)
+	}
+	// TODO: (Vyr) is it possible to unset a filter expiration with this API?
+	if form.ExpiresIn != nil {
+		filterColumns = append(filterColumns, "expires_at")
+		filter.ExpiresAt = time.Now().Add(time.Second * time.Duration(*form.ExpiresIn))
+	}
+	if form.Context != nil {
+		filterColumns = append(filterColumns,
+			"context_home",
+			"context_notifications",
+			"context_public",
+			"context_thread",
+			"context_account",
+		)
+		filter.ContextHome = util.Ptr(false)
+		filter.ContextNotifications = util.Ptr(false)
+		filter.ContextPublic = util.Ptr(false)
+		filter.ContextThread = util.Ptr(false)
+		filter.ContextAccount = util.Ptr(false)
+		for _, context := range *form.Context {
+			switch context {
+			case apimodel.FilterContextHome:
+				filter.ContextHome = util.Ptr(true)
+			case apimodel.FilterContextNotifications:
+				filter.ContextNotifications = util.Ptr(true)
+			case apimodel.FilterContextPublic:
+				filter.ContextPublic = util.Ptr(true)
+			case apimodel.FilterContextThread:
+				filter.ContextThread = util.Ptr(true)
+			case apimodel.FilterContextAccount:
+				filter.ContextAccount = util.Ptr(true)
+			default:
+				return nil, gtserror.NewErrorUnprocessableEntity(
+					fmt.Errorf("unsupported filter context '%s'", context),
+				)
+			}
+		}
+	}
+
+	// Temporarily detach keywords and statuses from filter, since we're not updating them below.
+	filterKeywords := filter.Keywords
+	filterStatuses := filter.Statuses
+	filter.Keywords = nil
+	filter.Statuses = nil
+
+	if err := p.state.DB.UpdateFilter(ctx, filter, filterColumns, nil, nil, nil); err != nil {
+		if errors.Is(err, db.ErrAlreadyExists) {
+			err = errors.New("you already have a filter with this title")
+			return nil, gtserror.NewErrorConflict(err, err.Error())
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// Re-attach keywords and statuses before returning.
+	filter.Keywords = filterKeywords
+	filter.Statuses = filterStatuses
+
+	return p.apiFilter(ctx, filter)
+}