enhance: allow custom watches to bypass on-mention email restriction (#39652)

Users with "Only Email on Mention" can now still receive email for the
events they picked in a custom repository watch, covering issues, pull
requests and releases. The setting is renamed to "Only Email on Mention
and Custom Watches" to make this explicit, matching GitHub's
"Participating, @mentions and custom".

"All activity" watches don't bypass the setting, because they are also
created automatically by `AUTO_WATCH_NEW_REPOS` for repository creators
and team members. To keep picking every event distinct from "All
activity", the custom watch dialog now stores a new `WatchModeCustom`.
Existing custom watches keep working without a migration.

## Screenshots
### Before
<img width="1650" height="675" alt="grafik"
src="https://github.com/user-attachments/assets/ecc56e20-cd05-41e9-a840-607b352c50a8"
/>

### After
<img width="1657" height="671" alt="grafik"
src="https://github.com/user-attachments/assets/a406db94-3ac4-4587-b840-0cd472b135c5"
/>


Addresses https://github.com/openSUSE/openSUSE-git/issues/183
Ref: https://github.com/go-gitea/gitea/issues/35492

---------

Co-authored-by: bircni <bircni@icloud.com>
Co-authored-by: Giteabot <teabot@gitea.io>

models/issues/issue_search.go

@@ -477,7 +477,7 @@ func applySubscribedCondition(sess db.Session, subscriberID int64) {
 				Select("repo_id").
 				From("watch").
 				Where(builder.And(builder.Eq{"user_id": subscriberID},
-					builder.In("mode", repo_model.WatchModeNormal, repo_model.WatchModeAuto))),
+					builder.In("mode", repo_model.WatchModeNormal, repo_model.WatchModeAuto, repo_model.WatchModeCustom))),
 			),
 		),
 	)

models/repo/watch.go

@@ -20,9 +20,10 @@ type WatchMode int8
 const (
 	WatchModeNone WatchMode = iota // 0 watch nothing unless mentioned
 
-	WatchModeNormal // 1 proactively watching (all or custom)
+	WatchModeNormal // 1 proactively watching (all, or custom before WatchModeCustom)
 	WatchModeDont   // 2 ignore the repo
 	WatchModeAuto   // 3 automatically watching (from AutoWatchOnChanges)
+	WatchModeCustom // 4 watching the events picked in the custom watch options
 )
 
 // WatchType is the `watch` column gating one kind of notification
@@ -79,7 +80,7 @@ func (w *Watch) IsWatching() bool {
 
 // IsWatchingAll reports whether every event is enabled, which is the "all activity" mode
 func (w *Watch) IsWatchingAll() bool {
-	return w.IncludePullRequests && w.IncludeIssues && w.IncludeReleases
+	return w.Mode != WatchModeCustom && w.IncludePullRequests && w.IncludeIssues && w.IncludeReleases
 }
 
 func (w *Watch) IsWatchingAny() bool {
@@ -166,6 +167,9 @@ func WatchRepoAuto(ctx context.Context, doer *user_model.User, repo *Repository,
 	if user_model.IsUserBlockedBy(ctx, doer, repo.OwnerID) {
 		return user_model.ErrBlockedUser
 	}
+	if watch.Mode == WatchModeCustom { // keep the events the user picked
+		return nil
+	}
 
 	return watchRepoByMode(ctx, watch, WatchModeNormal)
 }
@@ -189,7 +193,7 @@ func WatchRepoWithOptions(ctx context.Context, doer *user_model.User, repo *Repo
 		if err != nil {
 			return err
 		}
-		if opts.Mode == WatchModeNormal {
+		if opts.Mode == WatchModeNormal || opts.Mode == WatchModeCustom {
 			_, err = db.GetEngine(ctx).Where("user_id=? AND repo_id=?", doer.ID, repo.ID).
 				Cols("include_pull_requests", "include_issues", "include_releases").
 				Update(&Watch{IncludePullRequests: opts.WatchPullRequests, IncludeIssues: opts.WatchIssues, IncludeReleases: opts.WatchReleases})
@@ -247,6 +251,16 @@ func GetRepoIgnorersIDs(ctx context.Context, repoID int64) ([]int64, error) {
 // but avoids joining with `user` for performance reasons
 // User permissions must be verified elsewhere if required
 func GetRepoWatchersIDs(ctx context.Context, repoID int64, watchType WatchType) ([]int64, error) {
+	return getRepoWatchersIDs(ctx, repoID, watchType, false)
+}
+
+// GetRepoCustomWatchersIDs is GetRepoWatchersIDs limited to custom watches, which unlike
+// watching all activity are never set up automatically (e.g. by AutoWatchNewRepos)
+func GetRepoCustomWatchersIDs(ctx context.Context, repoID int64, watchType WatchType) ([]int64, error) {
+	return getRepoWatchersIDs(ctx, repoID, watchType, true)
+}
+
+func getRepoWatchersIDs(ctx context.Context, repoID int64, watchType WatchType, customOnly bool) ([]int64, error) {
 	ids := make([]int64, 0, 64)
 	var watchColName string
 	switch watchType {
@@ -259,12 +273,19 @@ func GetRepoWatchersIDs(ctx context.Context, repoID int64, watchType WatchType)
 	default:
 		panic("invalid WatchType")
 	}
-	return ids, db.GetEngine(ctx).Table("watch").
+	sess := db.GetEngine(ctx).Table("watch").
 		Where("watch.repo_id=?", repoID).
 		And("watch.mode<>?", WatchModeDont).
-		And(builder.Eq{watchColName: true}).
-		Select("user_id").
-		Find(&ids)
+		And(builder.Eq{watchColName: true})
+	if customOnly { // matches SelectedMode() == "custom"
+		sess = sess.And(builder.Or(
+			builder.Eq{"watch.mode": WatchModeCustom},
+			builder.Eq{"watch.include_pull_requests": false},
+			builder.Eq{"watch.include_issues": false},
+			builder.Eq{"watch.include_releases": false},
+		))
+	}
+	return ids, sess.Select("user_id").Find(&ids)
 }
 
 // GetRepoWatchers returns range of users watching given repository.

models/repo/watch_test.go

@@ -145,7 +145,7 @@ func TestWatchOptions(t *testing.T) {
 	// repo 1 is watched by users 1, 4, 9 and 11, all with every event enabled
 	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
 	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
-	assert.NoError(t, repo_model.WatchRepoWithOptions(t.Context(), user, repo, repo_model.WatchOptions{Mode: repo_model.WatchModeNormal, WatchPullRequests: true}))
+	assert.NoError(t, repo_model.WatchRepoWithOptions(t.Context(), user, repo, repo_model.WatchOptions{Mode: repo_model.WatchModeNormal, WatchPullRequests: true})) // custom watches were stored like this before WatchModeCustom
 
 	for watchType, expected := range map[repo_model.WatchType][]int64{
 		repo_model.WatchPullRequests: {1, 4, 9, 11},
@@ -157,6 +157,20 @@ func TestWatchOptions(t *testing.T) {
 		assert.ElementsMatch(t, expected, ids, watchType)
 	}
 
+	// a custom watch picking every event differs from all activity, which can be set up automatically
+	customUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 4})
+	assert.NoError(t, repo_model.WatchRepoWithOptions(t.Context(), customUser, repo, repo_model.WatchOptions{Mode: repo_model.WatchModeCustom, WatchPullRequests: true, WatchIssues: true, WatchReleases: true}))
+	assert.NoError(t, repo_model.WatchRepoAuto(t.Context(), customUser, repo, true)) // must keep the custom watch
+	for watchType, expected := range map[repo_model.WatchType][]int64{
+		repo_model.WatchPullRequests: {1, 4},
+		repo_model.WatchIssues:       {4},
+		repo_model.WatchReleases:     {4},
+	} {
+		ids, err := repo_model.GetRepoCustomWatchersIDs(t.Context(), repo.ID, watchType)
+		assert.NoError(t, err)
+		assert.ElementsMatch(t, expected, ids, watchType)
+	}
+
 	// the options of one user must not show up for another
 	watches, err := repo_model.GetUserWatches(t.Context(), 4, []int64{repo.ID})
 	assert.NoError(t, err)
@@ -176,5 +190,6 @@ func TestWatchSelectedMode(t *testing.T) {
 	assert.Equal(t, "participate", (&repo_model.Watch{Mode: repo_model.WatchModeNormal}).SelectedMode())
 	assert.Equal(t, "ignore", (&repo_model.Watch{Mode: repo_model.WatchModeDont}).SelectedMode())
 	assert.Equal(t, "custom", (&repo_model.Watch{Mode: repo_model.WatchModeNormal, IncludeIssues: true}).SelectedMode())
+	assert.Equal(t, "custom", (&repo_model.Watch{Mode: repo_model.WatchModeCustom, IncludePullRequests: true, IncludeIssues: true, IncludeReleases: true}).SelectedMode())
 	assert.Equal(t, "all", (&repo_model.Watch{Mode: repo_model.WatchModeAuto, IncludePullRequests: true, IncludeIssues: true, IncludeReleases: true}).SelectedMode())
 }