Allow configuring default PR base branch (fixes #36412)

models/git/branch.go

@@ -490,7 +490,8 @@ func FindRecentlyPushedNewBranches(ctx context.Context, doer *user_model.User, o
 		opts.CommitAfterUnix = time.Now().Add(-time.Hour * 2).Unix()
 	}
 
-	baseBranch, err := GetBranch(ctx, opts.BaseRepo.ID, opts.BaseRepo.DefaultBranch)
+	baseBranchName := opts.BaseRepo.GetDefaultPRBaseBranch(ctx)
+	baseBranch, err := GetBranch(ctx, opts.BaseRepo.ID, baseBranchName)
 	if err != nil {
 		return nil, err
 	}
@@ -555,7 +556,7 @@ func FindRecentlyPushedNewBranches(ctx context.Context, doer *user_model.User, o
 				BranchDisplayName: branchDisplayName,
 				BranchName:        branch.Name,
 				BranchLink:        fmt.Sprintf("%s/src/branch/%s", branch.Repo.Link(), util.PathEscapeSegments(branch.Name)),
-				BranchCompareURL:  branch.Repo.ComposeBranchCompareURL(opts.BaseRepo, branch.Name),
+				BranchCompareURL:  branch.Repo.ComposeBranchCompareURL(ctx, opts.BaseRepo, branch.Name),
 				CommitTime:        branch.CommitTime,
 			})
 		}

models/repo/pull_request_default.go

@@ -0,0 +1,99 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/modules/util"
+)
+
+// ErrDefaultPRBaseBranchNotExist represents an error that branch with such name does not exist.
+type ErrDefaultPRBaseBranchNotExist struct {
+	RepoID     int64
+	BranchName string
+}
+
+// IsErrDefaultPRBaseBranchNotExist checks if an error is an ErrDefaultPRBaseBranchNotExist.
+func IsErrDefaultPRBaseBranchNotExist(err error) bool {
+	_, ok := err.(ErrDefaultPRBaseBranchNotExist)
+	return ok
+}
+
+func (err ErrDefaultPRBaseBranchNotExist) Error() string {
+	return fmt.Sprintf("default PR base branch does not exist [repo_id: %d name: %s]", err.RepoID, err.BranchName)
+}
+
+func (err ErrDefaultPRBaseBranchNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
+// GetDefaultPRBaseBranchSetting returns the configured base branch for new pull requests.
+// It returns an empty string when unset or pull requests are disabled.
+func (repo *Repository) GetDefaultPRBaseBranchSetting(ctx context.Context) string {
+	prUnit, err := repo.GetUnit(ctx, unit.TypePullRequests)
+	if err != nil {
+		return ""
+	}
+	cfg := prUnit.PullRequestsConfig()
+	if cfg == nil {
+		return ""
+	}
+	return strings.TrimSpace(cfg.DefaultPRBaseBranch)
+}
+
+// GetDefaultPRBaseBranch returns the preferred base branch for new pull requests.
+// It falls back to the repository default branch when unset or invalid.
+func (repo *Repository) GetDefaultPRBaseBranch(ctx context.Context) string {
+	preferred := repo.GetDefaultPRBaseBranchSetting(ctx)
+	if preferred != "" {
+		exists, err := isBranchNameExists(ctx, repo.ID, preferred)
+		if err == nil && exists {
+			return preferred
+		}
+	}
+	return repo.DefaultBranch
+}
+
+// ValidateDefaultPRBaseBranch checks whether a preferred base branch is valid.
+func (repo *Repository) ValidateDefaultPRBaseBranch(ctx context.Context, branch string) error {
+	branch = strings.TrimSpace(branch)
+	if branch == "" {
+		return nil
+	}
+
+	exists, err := isBranchNameExists(ctx, repo.ID, branch)
+	if err != nil {
+		return err
+	}
+	if !exists {
+		return ErrDefaultPRBaseBranchNotExist{
+			RepoID:     repo.ID,
+			BranchName: branch,
+		}
+	}
+	return nil
+}
+
+func isBranchNameExists(ctx context.Context, repoID int64, branchName string) (bool, error) {
+	type branch struct {
+		IsDeleted bool `xorm:"is_deleted"`
+	}
+	var b branch
+	has, err := db.GetEngine(ctx).
+		Where("repo_id = ?", repoID).
+		And("name = ?", branchName).
+		Get(&b)
+	if err != nil {
+		return false, err
+	}
+	if !has {
+		return false, nil
+	}
+	return !b.IsDeleted, nil
+}

models/repo/pull_request_default_test.go

@@ -0,0 +1,35 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDefaultPRBaseBranchSelection(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	ctx := t.Context()
+	repo := unittest.AssertExistsAndLoadBean(t, &Repository{ID: 1})
+
+	assert.Equal(t, repo.DefaultBranch, repo.GetDefaultPRBaseBranch(ctx))
+
+	repo.Units = nil
+	prUnit, err := repo.GetUnit(ctx, unit.TypePullRequests)
+	assert.NoError(t, err)
+	prConfig := prUnit.PullRequestsConfig()
+	prConfig.DefaultPRBaseBranch = "branch2"
+	prUnit.Config = prConfig
+	assert.NoError(t, UpdateRepoUnit(ctx, prUnit))
+	repo.Units = nil
+	assert.Equal(t, "branch2", repo.GetDefaultPRBaseBranch(ctx))
+
+	err = repo.ValidateDefaultPRBaseBranch(ctx, "does-not-exist")
+	assert.True(t, IsErrDefaultPRBaseBranchNotExist(err))
+}

models/repo/repo.go

@@ -613,16 +613,17 @@ func (repo *Repository) ComposeCompareURL(oldCommitID, newCommitID string) strin
 	return fmt.Sprintf("%s/%s/compare/%s...%s", url.PathEscape(repo.OwnerName), url.PathEscape(repo.Name), util.PathEscapeSegments(oldCommitID), util.PathEscapeSegments(newCommitID))
 }
 
-func (repo *Repository) ComposeBranchCompareURL(baseRepo *Repository, branchName string) string {
+func (repo *Repository) ComposeBranchCompareURL(ctx context.Context, baseRepo *Repository, branchName string) string {
 	if baseRepo == nil {
 		baseRepo = repo
 	}
+	baseBranch := baseRepo.GetDefaultPRBaseBranch(ctx)
 	var cmpBranchEscaped string
 	if repo.ID != baseRepo.ID {
 		cmpBranchEscaped = fmt.Sprintf("%s/%s:", url.PathEscape(repo.OwnerName), url.PathEscape(repo.Name))
 	}
 	cmpBranchEscaped = fmt.Sprintf("%s%s", cmpBranchEscaped, util.PathEscapeSegments(branchName))
-	return fmt.Sprintf("%s/compare/%s...%s", baseRepo.Link(), util.PathEscapeSegments(baseRepo.DefaultBranch), cmpBranchEscaped)
+	return fmt.Sprintf("%s/compare/%s...%s", baseRepo.Link(), util.PathEscapeSegments(baseBranch), cmpBranchEscaped)
 }
 
 // IsOwnedBy returns true when user owns this repository

models/repo/repo_unit.go

@@ -131,6 +131,7 @@ type PullRequestsConfig struct {
 	DefaultDeleteBranchAfterMerge bool
 	DefaultMergeStyle             MergeStyle
 	DefaultAllowMaintainerEdit    bool
+	DefaultPRBaseBranch           string
 }
 
 // FromDB fills up a PullRequestsConfig from serialized format.

modules/git/gitcmd/command.go

@@ -445,6 +445,17 @@ func (c *Command) closePipeFiles(files []*os.File) {
 }
 
 func (c *Command) Wait() error {
+	done := make(chan struct{})
+	defer close(done)
+	if c.cmd != nil && c.cmd.Process != nil && c.cmdCtx != nil {
+		go func() {
+			select {
+			case <-c.cmdCtx.Done():
+				_ = c.cmd.Process.Kill()
+			case <-done:
+			}
+		}()
+	}
 	defer func() {
 		// The reader in another goroutine might be still reading the stdout, so we shouldn't close the pipes here
 		// MakeStdoutPipe returns a closer function to force callers to close the pipe correctly

modules/git/gitcmd/command_test.go

@@ -121,10 +121,15 @@ func TestRunWithContextTimeout(t *testing.T) {
 		require.NoError(t, err)
 	})
 	t.Run("WithTimeout", func(t *testing.T) {
-		cmd := NewCommand("hash-object", "--stdin")
-		_, _, pipeClose := cmd.MakeStdinStdoutPipe()
-		defer pipeClose()
-		err := cmd.WithTimeout(1 * time.Millisecond).Run(t.Context())
+		cmd := NewCommand("cat-file", "--batch")
+		stdin, stdinClose := cmd.MakeStdinPipe()
+		defer stdinClose()
+		time.AfterFunc(200*time.Millisecond, func() { _ = stdin.Close() })
+		ctx, cancel := context.WithTimeout(t.Context(), 2*time.Second)
+		defer cancel()
+		start := time.Now()
+		err := cmd.WithTimeout(50 * time.Millisecond).Run(ctx)
 		require.ErrorIs(t, err, context.DeadlineExceeded)
+		require.Less(t, time.Since(start), time.Second)
 	})
 }

modules/structs/repo.go

@@ -58,26 +58,27 @@ type Repository struct {
 	Fork        bool   `json:"fork"`
 	Template    bool   `json:"template"`
 	// the original repository if this repository is a fork, otherwise null
-	Parent        *Repository `json:"parent,omitempty"`
-	Mirror        bool        `json:"mirror"`
-	Size          int         `json:"size"`
-	Language      string      `json:"language"`
-	LanguagesURL  string      `json:"languages_url"`
-	HTMLURL       string      `json:"html_url"`
-	URL           string      `json:"url"`
-	Link          string      `json:"link"`
-	SSHURL        string      `json:"ssh_url"`
-	CloneURL      string      `json:"clone_url"`
-	OriginalURL   string      `json:"original_url"`
-	Website       string      `json:"website"`
-	Stars         int         `json:"stars_count"`
-	Forks         int         `json:"forks_count"`
-	Watchers      int         `json:"watchers_count"`
-	OpenIssues    int         `json:"open_issues_count"`
-	OpenPulls     int         `json:"open_pr_counter"`
-	Releases      int         `json:"release_counter"`
-	DefaultBranch string      `json:"default_branch"`
-	Archived      bool        `json:"archived"`
+	Parent              *Repository `json:"parent,omitempty"`
+	Mirror              bool        `json:"mirror"`
+	Size                int         `json:"size"`
+	Language            string      `json:"language"`
+	LanguagesURL        string      `json:"languages_url"`
+	HTMLURL             string      `json:"html_url"`
+	URL                 string      `json:"url"`
+	Link                string      `json:"link"`
+	SSHURL              string      `json:"ssh_url"`
+	CloneURL            string      `json:"clone_url"`
+	OriginalURL         string      `json:"original_url"`
+	Website             string      `json:"website"`
+	Stars               int         `json:"stars_count"`
+	Forks               int         `json:"forks_count"`
+	Watchers            int         `json:"watchers_count"`
+	OpenIssues          int         `json:"open_issues_count"`
+	OpenPulls           int         `json:"open_pr_counter"`
+	Releases            int         `json:"release_counter"`
+	DefaultBranch       string      `json:"default_branch"`
+	DefaultPRBaseBranch string      `json:"default_pr_base_branch,omitempty"`
+	Archived            bool        `json:"archived"`
 	// swagger:strfmt date-time
 	Created time.Time `json:"created_at"`
 	// swagger:strfmt date-time

options/locale/locale_en-US.json

@@ -2120,6 +2120,10 @@
   "repo.settings.pulls.ignore_whitespace": "Ignore Whitespace for Conflicts",
   "repo.settings.pulls.enable_autodetect_manual_merge": "Enable autodetect manual merge (Note: In some special cases, misjudgments can occur)",
   "repo.settings.pulls.allow_rebase_update": "Enable updating pull request branch by rebase",
+  "repo.settings.pulls.default_pr_base_branch": "Default PR base branch",
+  "repo.settings.pulls.default_pr_base_branch_desc": "Preselect this branch as the base when creating a new pull request. Leave empty to use the repository default branch.",
+  "repo.settings.pulls.default_pr_base_branch_default": "Use repository default branch (%s)",
+  "repo.settings.pulls.default_pr_base_branch_invalid": "Default PR base branch does not exist.",
   "repo.settings.pulls.default_delete_branch_after_merge": "Delete pull request branch after merge by default",
   "repo.settings.pulls.default_allow_edits_from_maintainers": "Allow edits from maintainers by default",
   "repo.settings.releases_desc": "Enable Repository Releases",

routers/web/repo/compare.go

@@ -247,7 +247,7 @@ func ParseCompareInfo(ctx *context.Context) *git_service.CompareInfo {
 	}
 
 	// 4 get base and head refs
-	baseRefName := util.IfZero(compareReq.BaseOriRef, baseRepo.DefaultBranch)
+	baseRefName := util.IfZero(compareReq.BaseOriRef, baseRepo.GetDefaultPRBaseBranch(ctx))
 	headRefName := util.IfZero(compareReq.HeadOriRef, headRepo.DefaultBranch)
 
 	baseRef := ctx.Repo.GitRepo.UnstableGuessRefByShortName(baseRefName)

routers/web/repo/setting/setting.go

@@ -28,6 +28,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/validation"
 	"code.gitea.io/gitea/modules/web"
+	repo_router "code.gitea.io/gitea/routers/web/repo"
 	actions_service "code.gitea.io/gitea/services/actions"
 	"code.gitea.io/gitea/services/context"
 	"code.gitea.io/gitea/services/forms"
@@ -88,6 +89,11 @@ func SettingsCtxData(ctx *context.Context) {
 		return
 	}
 	ctx.Data["PushMirrors"] = pushMirrors
+
+	repo_router.PrepareBranchList(ctx)
+	if ctx.Written() {
+		return
+	}
 }
 
 // Settings show a repository's settings page
@@ -554,6 +560,17 @@ func handleSettingsPostAdvanced(ctx *context.Context) {
 		}
 	}
 
+	defaultPRBaseBranch := strings.TrimSpace(form.DefaultPRBaseBranch)
+	if err := repo.ValidateDefaultPRBaseBranch(ctx, defaultPRBaseBranch); err != nil {
+		if repo_model.IsErrDefaultPRBaseBranchNotExist(err) {
+			ctx.Flash.Error(ctx.Tr("repo.settings.pulls.default_pr_base_branch_invalid"))
+			ctx.Redirect(repo.Link() + "/settings")
+			return
+		}
+		ctx.ServerError("ValidateDefaultPRBaseBranch", err)
+		return
+	}
+
 	if form.EnableIssues && form.EnableExternalTracker && !unit_model.TypeExternalTracker.UnitGlobalDisabled() {
 		if !validation.IsValidExternalURL(form.ExternalTrackerURL) {
 			ctx.Flash.Error(ctx.Tr("repo.settings.external_tracker_url_error"))
@@ -622,6 +639,7 @@ func handleSettingsPostAdvanced(ctx *context.Context) {
 			DefaultDeleteBranchAfterMerge: form.DefaultDeleteBranchAfterMerge,
 			DefaultMergeStyle:             repo_model.MergeStyle(form.PullsDefaultMergeStyle),
 			DefaultAllowMaintainerEdit:    form.DefaultAllowMaintainerEdit,
+			DefaultPRBaseBranch:           defaultPRBaseBranch,
 		}))
 	} else if !unit_model.TypePullRequests.UnitGlobalDisabled() {
 		deleteUnitTypes = append(deleteUnitTypes, unit_model.TypePullRequests)

services/context/repo.go

@@ -688,6 +688,11 @@ func RepoAssignment(ctx *Context) {
 	}
 	ctx.Data["CanCompareOrPull"] = canCompare
 	ctx.Data["PullRequestCtx"] = ctx.Repo.PullRequest
+	defaultPRBaseBranch := repo.GetDefaultPRBaseBranch(ctx)
+	if ctx.Repo.PullRequest.BaseRepo != nil {
+		defaultPRBaseBranch = ctx.Repo.PullRequest.BaseRepo.GetDefaultPRBaseBranch(ctx)
+	}
+	ctx.Data["DefaultPRBaseBranch"] = defaultPRBaseBranch
 
 	if ctx.Repo.Repository.Status == repo_model.RepositoryPendingTransfer {
 		repoTransfer, err := repo_model.GetPendingRepositoryTransfer(ctx, ctx.Repo.Repository)

services/convert/repository.go

@@ -235,6 +235,7 @@ func innerToRepo(ctx context.Context, repo *repo_model.Repository, permissionInR
 		DefaultDeleteBranchAfterMerge: defaultDeleteBranchAfterMerge,
 		DefaultMergeStyle:             string(defaultMergeStyle),
 		DefaultAllowMaintainerEdit:    defaultAllowMaintainerEdit,
+		DefaultPRBaseBranch:           repo.GetDefaultPRBaseBranchSetting(ctx),
 		AvatarURL:                     repo.AvatarLink(ctx),
 		Internal:                      !repo.IsPrivate && repo.Owner.Visibility == api.VisibleTypePrivate,
 		MirrorInterval:                mirrorInterval,

services/forms/repo_form.go

@@ -143,6 +143,7 @@ type RepoSettingForm struct {
 	PullsAllowRebaseUpdate           bool
 	DefaultDeleteBranchAfterMerge    bool
 	DefaultAllowMaintainerEdit       bool
+	DefaultPRBaseBranch              string `form:"default_pr_base_branch"`
 	EnableTimetracker                bool
 	AllowOnlyContributorsToTrackTime bool
 	EnableIssueDependencies          bool

services/repository/branch.go

@@ -841,6 +841,12 @@ func DeleteBranchAfterMerge(ctx context.Context, doer *user_model.User, prID int
 	if exist {
 		return errFailedToDelete(util.ErrUnprocessableContent)
 	}
+	if pr.HeadRepoID == pr.BaseRepoID {
+		preferred := pr.BaseRepo.GetDefaultPRBaseBranchSetting(ctx)
+		if preferred != "" && pr.HeadBranch == preferred {
+			return errFailedToDelete(util.ErrPermissionDenied)
+		}
+	}
 
 	if err := CanDeleteBranch(ctx, pr.HeadRepo, pr.HeadBranch, doer); err != nil {
 		if errors.Is(err, util.ErrPermissionDenied) {