enhance(codeowners): support section / glob / file view display / skip review request (#40243)

Document: https://gitea.com/gitea/docs/pulls/634 ([doc PR
preview](955ae7d75c/docs/usage/repository/code-owners.md))

1. If the pattern starts with `*` or contains `/*`, use our glob package
to parse it as glob to regexp
* Make it easier to use. Otherwise it's really ugly to keep writing a
lot of backslash escapes
2. Add GitLab-style "section" support
   * Fix #28926

```codeowners
[Section] @user
*.js
```

3. Add our annotation support, at the moment only need to support
review-request=true/false
    * Fix #40241

```codeowners
## review-request=false # this is global

*.js $user ## review-request=true # this is line-level

[Section] @user ## review-request=true # this is section-level
*.md
```

4. Add GitHub/GitLab-style "show codeowner when viewing a file"
    * Fix #28137

models/issues/code_owner.go

@@ -0,0 +1,256 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package issues
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	org_model "gitea.dev/models/organization"
+	user_model "gitea.dev/models/user"
+	"gitea.dev/modules/glob"
+	"gitea.dev/modules/optional"
+
+	"github.com/dlclark/regexp2/v2"
+)
+
+// GetCodeOwnersFromContent returns the code owners configuration
+// Return empty slice if files missing
+// Return warning messages on parsing errors
+// We're trying to do the best we can when parsing a file.
+// Invalid lines are skipped. Non-existent users and teams too.
+func GetCodeOwnersFromContent(ctx context.Context, data string) (rules []*CodeOwnerRule, warnings []string) {
+	globalReview := optional.None[bool]()
+	sectionReview := optional.None[bool]()
+	section := ""
+	var owners []string
+
+	lineNum := 0
+	for line := range strings.SplitSeq(data, "\n") {
+		lineNum++
+		line, reviewRequest, annotationWarnings := parseCodeOwnerAnnotation(line)
+		for _, warning := range annotationWarnings {
+			warnings = append(warnings, fmt.Sprintf("Line: %d: %s", lineNum, warning))
+		}
+		line = strings.TrimSpace(line)
+		if line == "" {
+			if reviewRequest.Has() {
+				globalReview = reviewRequest
+			}
+			continue
+		}
+
+		// To support section headers, there could be an edge case for end users:
+		// `[a-z] @user` now becomes a section header instead of a rule, but it is really rare to happen.
+		// A workaround is to use `/[a-z] @user` to make it a rule.
+		if heading := line; strings.HasPrefix(heading, "[") {
+			if end := strings.IndexByte(heading, ']'); end > 1 && (end == len(heading)-1 || heading[end+1] == ' ' || heading[end+1] == '\t') {
+				section = heading[1:end]
+				owners = TokenizeCodeOwnersLine(heading[end+1:])
+				sectionReview = reviewRequest
+				continue
+			}
+		}
+		tokens := TokenizeCodeOwnersLine(line)
+		if len(tokens) == 0 {
+			continue
+		}
+		if len(tokens) == 1 && len(owners) > 0 {
+			tokens = append(tokens, owners...)
+		}
+		if len(tokens) < 2 {
+			warnings = append(warnings, fmt.Sprintf("Line: %d: incorrect format", lineNum))
+			continue
+		}
+		rule, wr := ParseCodeOwnersLine(ctx, tokens)
+		for _, w := range wr {
+			warnings = append(warnings, fmt.Sprintf("Line: %d: %s", lineNum, w))
+		}
+		if rule == nil {
+			continue
+		}
+		rule.LineNum = lineNum
+
+		rule.Section = section
+		rule.ReviewRequest = reviewRequest
+		if !rule.ReviewRequest.Has() {
+			rule.ReviewRequest = sectionReview
+		}
+		if !rule.ReviewRequest.Has() {
+			rule.ReviewRequest = globalReview
+		}
+		rules = append(rules, rule)
+	}
+
+	return rules, warnings
+}
+
+// codeOwnerMatchTimeout bounds a single pattern match so a crafted pattern
+// cannot stall via catastrophic backtracking. See also the aggregate budget
+// enforced by the caller across the whole rules×files match loop.
+const codeOwnerMatchTimeout = 150 * time.Millisecond
+
+type CodeOwnerRule struct {
+	LineNum       int
+	Section       string
+	ReviewRequest optional.Option[bool]
+
+	Rule     *regexp2.Regexp // it supports negative lookahead, does better for end users
+	Negative bool
+
+	// TODO: these objects should not be loaded here, but rather lazily when needed.
+	// The parsed rule should only contain the user/team names.
+	Users []*user_model.User
+	Teams []*org_model.Team
+}
+
+func ParseCodeOwnersLine(ctx context.Context, tokens []string) (rule *CodeOwnerRule, warnings []string) {
+	rule = &CodeOwnerRule{Negative: strings.HasPrefix(tokens[0], "!")}
+
+	// Strip leading "!" for negative rules, then strip leading "/" since
+	// git returns relative paths (e.g. "docs/foo.md" not "/docs/foo.md")
+	// and the regex is already anchored with ^...$, so the "/" is redundant.
+	pattern := strings.TrimPrefix(tokens[0], "!")
+	pattern = strings.TrimPrefix(pattern, "/")
+	expr := fmt.Sprintf("^%s$", pattern)
+
+	// To make life easier, we support glob expressions if the pattern contains a "*" or "/*" (e.g. "*.md" or "docs/*.md")
+	// However, "src/test\\..*\\.js" is still the only way because "src/test.*.js" can't be used as a glob at the moment.
+	// TODO: In the future, maybe it's better to introduce a new annotation to specify the pattern type, e.g.: "pattern-syntax=glob" or "pattern-syntax=regexp"
+	if strings.HasPrefix(pattern, "*") || strings.Contains(pattern, "/*") {
+		compiled, compileErr := glob.CompileToRegexp(pattern)
+		if compileErr != nil {
+			return nil, []string{fmt.Sprintf("incorrect codeowner glob: %s", compileErr)}
+		}
+		expr = compiled.String()
+	}
+
+	var err error
+	rule.Rule, err = regexp2.Compile(expr, regexp2.None)
+	if err != nil {
+		warnings = append(warnings, fmt.Sprintf("incorrect codeowner regexp: %s", err))
+		return nil, warnings
+	}
+
+	// Bound matching time so user-supplied patterns cannot stall PR creation via catastrophic backtracking.
+	rule.Rule.MatchTimeout = codeOwnerMatchTimeout
+
+	for _, user := range tokens[1:] {
+		user = strings.TrimPrefix(user, "@")
+
+		// Only @org/team can contain slashes
+		if strings.Contains(user, "/") {
+			s := strings.Split(user, "/")
+			if len(s) != 2 {
+				warnings = append(warnings, "incorrect codeowner group: "+user)
+				continue
+			}
+			orgName := s[0]
+			teamName := s[1]
+
+			org, err := org_model.GetOrgByName(ctx, orgName)
+			if err != nil {
+				warnings = append(warnings, "incorrect codeowner organization: "+user)
+				continue
+			}
+			teams, err := org.LoadTeams(ctx)
+			if err != nil {
+				warnings = append(warnings, "incorrect codeowner team: "+user)
+				continue
+			}
+
+			for _, team := range teams {
+				if team.Name == teamName {
+					rule.Teams = append(rule.Teams, team)
+				}
+			}
+		} else {
+			u, err := user_model.GetUserByName(ctx, user)
+			if err != nil {
+				warnings = append(warnings, "incorrect codeowner user: "+user)
+				continue
+			}
+			rule.Users = append(rule.Users, u)
+		}
+	}
+
+	if len(rule.Users) == 0 && len(rule.Teams) == 0 {
+		warnings = append(warnings, "no users/groups matched")
+		return nil, warnings
+	}
+
+	return rule, warnings
+}
+
+func TokenizeCodeOwnersLine(line string) (tokens []string) {
+	line = strings.TrimSpace(line)
+	line = strings.ReplaceAll(line, "\t", " ")
+	if line == "" {
+		return nil
+	}
+
+	escape := false
+	var token strings.Builder
+	for _, char := range line {
+		if escape {
+			token.WriteRune(char)
+			escape = false
+		} else if char == '\\' {
+			escape = true
+		} else if char == '#' {
+			break
+		} else if char == ' ' {
+			if token.Len() > 0 {
+				tokens = append(tokens, token.String())
+				token.Reset()
+			}
+		} else {
+			token.WriteRune(char)
+		}
+	}
+
+	if token.Len() > 0 {
+		tokens = append(tokens, token.String())
+	}
+
+	return tokens
+}
+
+func parseCodeOwnerAnnotation(line string) (string, optional.Option[bool], []string) {
+	escape := false
+	for i := 0; i < len(line); i++ {
+		if escape {
+			escape = false
+			continue
+		}
+		if line[i] == '\\' {
+			escape = true
+			continue
+		}
+		if line[i] != '#' {
+			continue
+		}
+		review := optional.None[bool]()
+		var warnings []string
+		if strings.HasPrefix(line[i:], "##") {
+			annotation, _, _ := strings.Cut(line[i+2:], "#")
+			for field := range strings.FieldsSeq(annotation) {
+				key, value, ok := strings.Cut(field, "=")
+				if key != "review-request" {
+					warnings = append(warnings, "unknown codeowner annotation: "+key)
+					continue
+				}
+				if !ok || (value != "true" && value != "false") {
+					warnings = append(warnings, "incorrect review-request annotation: "+field)
+					continue
+				}
+				review = optional.Some(value == "true")
+			}
+		}
+		return line[:i], review, warnings
+	}
+	return line, optional.None[bool](), nil
+}

models/issues/pull.go

@@ -10,7 +10,6 @@ import (
 	"fmt"
 	"io"
 	"strings"
-	"time"
 
 	"gitea.dev/models/db"
 	git_model "gitea.dev/models/git"
@@ -24,7 +23,6 @@ import (
 	"gitea.dev/modules/timeutil"
 	"gitea.dev/modules/util"
 
-	"github.com/dlclark/regexp2/v2"
 	"xorm.io/builder"
 )
 
@@ -825,162 +823,6 @@ func MergeBlockedByOutdatedBranch(protectBranch *git_model.ProtectedBranch, pr *
 	return protectBranch.BlockOnOutdatedBranch && pr.CommitsBehind > 0
 }
 
-// GetCodeOwnersFromContent returns the code owners configuration
-// Return empty slice if files missing
-// Return warning messages on parsing errors
-// We're trying to do the best we can when parsing a file.
-// Invalid lines are skipped. Non-existent users and teams too.
-func GetCodeOwnersFromContent(ctx context.Context, data string) ([]*CodeOwnerRule, []string) {
-	if len(data) == 0 {
-		return nil, nil
-	}
-
-	rules := make([]*CodeOwnerRule, 0)
-	lines := strings.Split(data, "\n")
-	warnings := make([]string, 0)
-
-	for i, line := range lines {
-		tokens := TokenizeCodeOwnersLine(line)
-		if len(tokens) == 0 {
-			continue
-		} else if len(tokens) < 2 {
-			warnings = append(warnings, fmt.Sprintf("Line: %d: incorrect format", i+1))
-			continue
-		}
-		rule, wr := ParseCodeOwnersLine(ctx, tokens)
-		for _, w := range wr {
-			warnings = append(warnings, fmt.Sprintf("Line: %d: %s", i+1, w))
-		}
-		if rule == nil {
-			continue
-		}
-
-		rules = append(rules, rule)
-	}
-
-	return rules, warnings
-}
-
-// codeOwnerMatchTimeout bounds a single pattern match so a crafted pattern
-// cannot stall via catastrophic backtracking. See also the aggregate budget
-// enforced by the caller across the whole rules×files match loop.
-const codeOwnerMatchTimeout = 150 * time.Millisecond
-
-type CodeOwnerRule struct {
-	Rule     *regexp2.Regexp // it supports negative lookahead, does better for end users
-	Negative bool
-	Users    []*user_model.User
-	Teams    []*org_model.Team
-}
-
-func ParseCodeOwnersLine(ctx context.Context, tokens []string) (*CodeOwnerRule, []string) {
-	var err error
-	rule := &CodeOwnerRule{
-		Users:    make([]*user_model.User, 0),
-		Teams:    make([]*org_model.Team, 0),
-		Negative: strings.HasPrefix(tokens[0], "!"),
-	}
-
-	warnings := make([]string, 0)
-
-	// Strip leading "!" for negative rules, then strip leading "/" since
-	// git returns relative paths (e.g. "docs/foo.md" not "/docs/foo.md")
-	// and the regex is already anchored with ^...$, so the "/" is redundant.
-	pattern := strings.TrimPrefix(tokens[0], "!")
-	pattern = strings.TrimPrefix(pattern, "/")
-	expr := fmt.Sprintf("^%s$", pattern)
-	rule.Rule, err = regexp2.Compile(expr, regexp2.None)
-	if err != nil {
-		warnings = append(warnings, fmt.Sprintf("incorrect codeowner regexp: %s", err))
-		return nil, warnings
-	}
-	// Bound matching time so user-supplied patterns cannot stall PR creation via catastrophic backtracking.
-	rule.Rule.MatchTimeout = codeOwnerMatchTimeout
-
-	for _, user := range tokens[1:] {
-		user = strings.TrimPrefix(user, "@")
-
-		// Only @org/team can contain slashes
-		if strings.Contains(user, "/") {
-			s := strings.Split(user, "/")
-			if len(s) != 2 {
-				warnings = append(warnings, "incorrect codeowner group: "+user)
-				continue
-			}
-			orgName := s[0]
-			teamName := s[1]
-
-			org, err := org_model.GetOrgByName(ctx, orgName)
-			if err != nil {
-				warnings = append(warnings, "incorrect codeowner organization: "+user)
-				continue
-			}
-			teams, err := org.LoadTeams(ctx)
-			if err != nil {
-				warnings = append(warnings, "incorrect codeowner team: "+user)
-				continue
-			}
-
-			for _, team := range teams {
-				if team.Name == teamName {
-					rule.Teams = append(rule.Teams, team)
-				}
-			}
-		} else {
-			u, err := user_model.GetUserByName(ctx, user)
-			if err != nil {
-				warnings = append(warnings, "incorrect codeowner user: "+user)
-				continue
-			}
-			rule.Users = append(rule.Users, u)
-		}
-	}
-
-	if (len(rule.Users) == 0) && (len(rule.Teams) == 0) {
-		warnings = append(warnings, "no users/groups matched")
-		return nil, warnings
-	}
-
-	return rule, warnings
-}
-
-func TokenizeCodeOwnersLine(line string) []string {
-	if len(line) == 0 {
-		return nil
-	}
-
-	line = strings.TrimSpace(line)
-	line = strings.ReplaceAll(line, "\t", " ")
-
-	tokens := make([]string, 0)
-
-	escape := false
-	token := ""
-	for _, char := range line {
-		if escape {
-			token += string(char)
-			escape = false
-		} else if string(char) == "\\" {
-			escape = true
-		} else if string(char) == "#" {
-			break
-		} else if string(char) == " " {
-			if len(token) > 0 {
-				tokens = append(tokens, token)
-				token = ""
-			}
-		} else {
-			token += string(char)
-		}
-	}
-
-	if len(token) > 0 {
-		tokens = append(tokens, token)
-	}
-
-	return tokens
-}
-
 // InsertPullRequests inserted pull requests
 func InsertPullRequests(ctx context.Context, prs ...*PullRequest) error {
 	return db.WithTx(ctx, func(ctx context.Context) error {

models/issues/pull_test.go

@@ -44,6 +44,7 @@ func TestPullRequest(t *testing.T) {
 	t.Run("ParseCodeOwnersLine", testParseCodeOwnersLine)
 	t.Run("CodeOwnerAbsolutePathPatterns", testCodeOwnerAbsolutePathPatterns)
 	t.Run("CodeOwnerPatternMatchTimeout", testCodeOwnerPatternMatchTimeout)
+	t.Run("CodeOwnerSectionsAndAnnotations", testCodeOwnerSectionsAndAnnotations)
 	t.Run("GetApprovers", testGetApprovers)
 	t.Run("GetPullRequestByMergedCommit", testGetPullRequestByMergedCommit)
 	t.Run("Migrate_InsertPullRequests", testMigrateInsertPullRequests)
@@ -335,7 +336,7 @@ func testParseCodeOwnersLine(t *testing.T) {
 
 	given := []CodeOwnerTest{
 		{Line: "", Tokens: nil},
-		{Line: "# comment", Tokens: []string{}},
+		{Line: "# comment", Tokens: nil},
 		{Line: "!.* @user1 @org1/team1", Tokens: []string{"!.*", "@user1", "@org1/team1"}},
 		{Line: `.*\\.js @user2 #comment`, Tokens: []string{`.*\.js`, "@user2"}},
 		{Line: `docs/(aws|google|azure)/[^/]*\\.(md|txt) @org3 @org2/team2`, Tokens: []string{`docs/(aws|google|azure)/[^/]*\.(md|txt)`, "@org3", "@org2/team2"}},
@@ -347,7 +348,7 @@ func testParseCodeOwnersLine(t *testing.T) {
 
 	for _, g := range given {
 		tokens := issues_model.TokenizeCodeOwnersLine(g.Line)
-		assert.Equal(t, g.Tokens, tokens, "Codeowners tokenizer failed")
+		assert.Equal(t, g.Tokens, tokens, "Codeowners tokenizer failed: input=%s", g.Line)
 	}
 }
 
@@ -448,3 +449,49 @@ func testMigrateInsertPullRequests(t *testing.T) {
 
 	unittest.CheckConsistencyFor(t, &issues_model.Issue{}, &issues_model.PullRequest{})
 }
+
+func testCodeOwnerSectionsAndAnnotations(t *testing.T) {
+	rules, warnings := issues_model.GetCodeOwnersFromContent(t.Context(), "*.js @user5\n[Docs] @user1\n*.md\n")
+	require.Empty(t, warnings)
+	require.Len(t, rules, 2)
+	for _, rule := range rules {
+		assert.False(t, rule.ReviewRequest.Has())
+	}
+
+	rules, warnings = issues_model.GetCodeOwnersFromContent(t.Context(), `## review-request=false # global
+*.js @user5 ## review-request=true # line
+[Documentation] @user1 ## review-request=true # section
+*.md
+/docs/* @user5 ## review-request=false
+[Other Section] @user5
+*.txt
+`)
+	match := func(rule *issues_model.CodeOwnerRule, path string) bool {
+		v, _ := rule.Rule.MatchString(path)
+		return v
+	}
+	require.Empty(t, warnings)
+	require.Len(t, rules, 4)
+	assert.True(t, rules[0].ReviewRequest.Value())
+	assert.True(t, match(rules[0], "src/app.js"))
+	assert.False(t, match(rules[0], "appXjs"))
+	assert.Equal(t, "Documentation", rules[1].Section)
+	assert.Equal(t, "user1", rules[1].Users[0].Name)
+	assert.True(t, rules[1].ReviewRequest.Value())
+	assert.Equal(t, "user5", rules[2].Users[0].Name)
+	assert.False(t, rules[2].ReviewRequest.Value())
+	assert.True(t, match(rules[2], "docs/guide.md"))
+	assert.False(t, match(rules[2], "other/docs/guide.md"))
+	assert.False(t, rules[3].ReviewRequest.Value())
+
+	rules, warnings = issues_model.GetCodeOwnersFromContent(t.Context(), "*.js @user5 ## review-request=invalid\n*[ @user5\n")
+	require.Len(t, rules, 1)
+	assert.False(t, rules[0].ReviewRequest.Has())
+	require.Len(t, warnings, 2)
+
+	rules, warnings = issues_model.GetCodeOwnersFromContent(t.Context(), `file\#name @user5 ## review-request=false`)
+	require.Empty(t, warnings)
+	require.Len(t, rules, 1)
+	assert.True(t, match(rules[0], "file#name"))
+	assert.False(t, rules[0].ReviewRequest.Value())
+}

modules/glob/glob.go

@@ -196,6 +196,14 @@ func Compile(pattern string, separators ...rune) (Glob, error) {
 	return initGlobCompiler(&globCompiler{}, pattern, separators)
 }
 
+func CompileToRegexp(pattern string, separators ...rune) (*regexp.Regexp, error) {
+	compiler := &globCompiler{}
+	if _, err := initGlobCompiler(compiler, pattern, separators); err != nil {
+		return nil, err
+	}
+	return compiler.regexp, nil
+}
+
 func CompileWorkflow(pattern string) (Glob, error) {
 	return initGlobCompiler(&globCompiler{
 		regexpQuestion:     true,

options/locale/locale_en-US.json

@@ -1731,6 +1731,7 @@
   "repo.issues.review.content.empty": "You need to leave a comment indicating the requested change(s).",
   "repo.issues.review.reject": "requested changes %s",
   "repo.issues.review.wait": "was requested for review %s",
+  "repo.codeowners": "Code owners",
   "repo.issues.review.codeowners_rules": "CODEOWNERS rules",
   "repo.issues.review.add_review_request": "requested review from %s %s",
   "repo.issues.review.remove_review_request": "removed review request for %s %s",

routers/web/repo/view_file.go

@@ -9,10 +9,12 @@ import (
 	"image"
 	"io"
 	"path"
+	"slices"
 	"strings"
 
 	git_model "gitea.dev/models/git"
 	issue_model "gitea.dev/models/issues"
+	org_model "gitea.dev/models/organization"
 	"gitea.dev/models/renderhelper"
 	user_model "gitea.dev/models/user"
 	"gitea.dev/modules/actions"
@@ -153,9 +155,53 @@ func handleFileViewRenderImage(ctx *context.Context, fInfo *fileInfo, prefetchBu
 	return true
 }
 
+type fileCodeOwner struct {
+	CodeOwnerName string
+	CodeOwnerLink string
+}
+
+func prepareFileCodeOwners(ctx *context.Context) {
+	rules, warnings1, err := issue_service.GetCodeOwnerRules(ctx, ctx.Repo.GitRepo, ctx.Repo.Commit)
+	if msg, _ := util.ErrorUnwrapForUser(err); msg != "" {
+		ctx.Flash.Error(msg, true)
+		return
+	} else if err != nil {
+		log.Error("GetCodeOwnerRules: failed to read CODEOWNERS file at repo %s commit %s: %v", ctx.Repo.Repository.LogString(), ctx.Repo.CommitID, err)
+		return
+	}
+	matching, warnings2 := issue_service.MatchCodeOwnerRules(rules, []string{ctx.Repo.TreePath})
+	warnings := slices.Concat(warnings1, warnings2)
+	if len(warnings) > 0 {
+		ctx.Flash.Warning(strings.Join(warnings, "\n"), true)
+	}
+
+	var owners []fileCodeOwner
+	seen := make(map[string]bool)
+	add := func(name, link string) {
+		if !seen[link] {
+			owners = append(owners, fileCodeOwner{name, link})
+			seen[link] = true
+		}
+	}
+	for _, rule := range matching {
+		for _, user := range rule.Users {
+			add("@"+user.Name, user.HomeLink())
+		}
+		for _, team := range rule.Teams {
+			org, err := org_model.GetOrgByID(ctx, team.OrgID)
+			if err != nil {
+				continue
+			}
+			add("@"+org.Name+"/"+team.Name, org.HomeLink()+"/teams/"+util.PathEscapeSegments(team.LowerName))
+		}
+	}
+	ctx.Data["FileCodeOwners"] = owners
+}
+
 func prepareFileView(ctx *context.Context, entry *git.TreeEntry) {
 	ctx.Data["IsViewFile"] = true
 	ctx.Data["HideRepoInfo"] = true
+	prepareFileCodeOwners(ctx)
 
 	if !prepareLatestCommitInfo(ctx) {
 		return

services/issue/pull.go

@@ -5,20 +5,24 @@ package issue
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"slices"
+	"sync"
 	"time"
 
 	"gitea.dev/models/db"
 	git_model "gitea.dev/models/git"
 	issues_model "gitea.dev/models/issues"
 	org_model "gitea.dev/models/organization"
+	repo_model "gitea.dev/models/repo"
 	user_model "gitea.dev/models/user"
 	"gitea.dev/modules/git"
 	"gitea.dev/modules/log"
 	"gitea.dev/modules/optional"
-	"gitea.dev/modules/setting"
+	"gitea.dev/modules/util"
 
+	lru "github.com/hashicorp/golang-lru/v2"
 	"xorm.io/builder"
 )
 
@@ -40,61 +44,82 @@ func IsCodeOwnerFile(f string) bool {
 }
 
 // Get all code owner rules for a given pr + repo combination.
-func getCodeOwnerRules(ctx context.Context, repo *git.Repository, pr *issues_model.PullRequest) ([]*issues_model.CodeOwnerRule, error) {
+func getCodeOwnerRules(ctx context.Context, repo *git.Repository, pr *issues_model.PullRequest) ([]*issues_model.CodeOwnerRule, []string, error) {
 	if err := pr.LoadBaseRepo(ctx); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	if err := pr.LoadIssue(ctx); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	pr.Issue.Repo = pr.BaseRepo
 
 	if pr.BaseRepo.IsFork {
-		return nil, nil
+		return nil, nil, nil
 	}
 
 	commit, err := repo.GetBranchCommit(ctx, pr.BaseBranch)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
+	}
+	return GetCodeOwnerRules(ctx, repo, commit)
 }
 
-	var data string
+const maxCodeOwnersFileSize = 3 * 1024 * 1024 // 3M as GitHub
 
+type repoCommitCodeOwnersItem struct {
+	content  string
+	warnings []string
+}
+
+var repoCommitCodeOwnersCache = sync.OnceValue(func() *lru.Cache[string, *repoCommitCodeOwnersItem] {
+	cache, _ := lru.New[string, *repoCommitCodeOwnersItem](50)
+	return cache
+})
+
+func getCodeOwnerRulesContent(ctx context.Context, repo *git.Repository, commit *git.Commit) (string, error) {
 	for _, file := range codeOwnerFiles {
 		blob, err := commit.GetBlobByPath(ctx, repo, file)
-		if err != nil {
+		if errors.Is(err, util.ErrNotExist) {
 			continue // no CODEOWNERS at this path, try the next candidate
+		} else if err != nil {
+			return "", err
 		}
 		// A truncated CODEOWNERS would silently drop rules, so fail closed rather
 		// than evaluate an incomplete file (the gate must not under-enforce).
-		if blob.Size(ctx) > setting.UI.MaxDisplayFileSize {
-			return nil, fmt.Errorf("CODEOWNERS file %q exceeds the maximum readable size", file)
+		if blob.Size(ctx) > maxCodeOwnersFileSize {
+			return "", util.ErrorWrap(util.ErrUnprocessableContent, "CODEOWNERS file exceeds the maximum readable size")
 		}
 		// The file exists but is unreadable: propagate instead of swallowing, so
 		// callers can fail closed instead of treating it as "no code owners".
-		data, err = blob.GetBlobContent(ctx, setting.UI.MaxDisplayFileSize)
+		data, err := blob.GetBlobContent(ctx, maxCodeOwnersFileSize)
 		if err != nil {
-			return nil, err
+			log.Error("GetCodeOwnerRules: failed to read CODEOWNERS file %q at commit %s: %v", file, commit.ID, err)
+			return "", util.ErrorWrap(util.ErrUnprocessableContent, "failed to read CODEOWNERS file")
 		}
-		break
+		return data, nil
+	}
+	return "", nil
 }
 
-	// no code owner file = no one to approve
-	if data == "" {
-		return nil, nil
+// GetCodeOwnerRules reads CODEOWNERS from the supplied commit.
+func GetCodeOwnerRules(ctx context.Context, repo *git.Repository, commit *git.Commit) (rules []*issues_model.CodeOwnerRule, warnings []string, err error) {
+	key := fmt.Sprintf("%s:%s", repo.GitRepoManagedID(), commit.ID)
+	it, ok := repoCommitCodeOwnersCache().Get(key)
+	if !ok {
+		content, err := getCodeOwnerRulesContent(ctx, repo, commit)
+		if err != nil {
+			return nil, nil, err
 		}
-
-	rules, warnings := issues_model.GetCodeOwnersFromContent(ctx, data)
-	for _, w := range warnings {
-		log.Warn("CODEOWNERS parsing for PR %s#%d: %s", pr.BaseRepo.FullName(), pr.ID, w)
+		it = &repoCommitCodeOwnersItem{content, warnings}
+		repoCommitCodeOwnersCache().Add(key, it)
 	}
-	if len(rules) == 0 {
-		return nil, nil
+	if len(it.warnings) != 0 {
+		return nil, it.warnings, nil
 	}
-
-	return rules, nil
+	rules, warnings = issues_model.GetCodeOwnersFromContent(ctx, it.content) // it loads database for users and teams, so we can't cache the rules
+	return rules, warnings, nil
 }
 
 // Get the matching code owner rules for a given pr + repo combination. The returned
@@ -110,7 +135,7 @@ func getMatchingCodeOwnerRules(ctx context.Context, pr *issues_model.PullRequest
 	}
 	defer closer.Close()
 
-	rules, err := getCodeOwnerRules(ctx, repo, pr)
+	rules, _, err := getCodeOwnerRules(ctx, repo, pr)
 	if err != nil {
 		return nil, false, err
 	}
@@ -131,30 +156,53 @@ func getMatchingCodeOwnerRules(ctx context.Context, pr *issues_model.PullRequest
 		return nil, false, err
 	}
 
-	matchingRules = make([]*issues_model.CodeOwnerRule, 0)
-	complete = true
-
-	// Bound the total time spent matching rules×files. The per-rule MatchTimeout
-	// only caps a single match; without an aggregate budget a crafted CODEOWNERS
-	// plus a PR touching many files could still exhaust CPU inside this loop.
-	matchDeadline := time.Now().Add(codeOwnerMatchBudget)
-ruleLoop:
-	for _, rule := range rules {
-		for _, f := range changedFiles {
-			if time.Now().After(matchDeadline) {
+	matchingRules, warnings := MatchCodeOwnerRules(rules, changedFiles)
+	complete = len(warnings) == 0
+	if !complete {
 		log.Warn("CODEOWNERS matching for PR %s#%d exceeded its time budget; some rules were not evaluated", pr.BaseRepo.FullName(), pr.ID)
-				complete = false
-				break ruleLoop
-			}
-			matched, _ := rule.Rule.MatchString(f) // err only happens when timeouts, any error can be considered as not matched
-			if matched != rule.Negative {
-				matchingRules = append(matchingRules, rule)
-				break
-			}
 	}
+	return matchingRules, complete, nil
 }
 
-	return matchingRules, complete, nil
+// MatchCodeOwnerRules selects matching rules, with the last match winning within each named section.
+func MatchCodeOwnerRules(rules []*issues_model.CodeOwnerRule, paths []string) (_ []*issues_model.CodeOwnerRule, warnings []string) {
+	selected := make(map[*issues_model.CodeOwnerRule]bool)
+	deadline := time.Now().Add(codeOwnerMatchBudget)
+	for _, path := range paths {
+		sections := make(map[string]*issues_model.CodeOwnerRule)
+		for _, rule := range rules {
+			if rule.Section == "" && selected[rule] {
+				continue
+			}
+			if time.Now().After(deadline) {
+				return nil, []string{"CODEOWNERS matching exceeded its time budget"}
+			}
+			patternMatched, err := rule.Rule.MatchString(path)
+			// err only happens when timeouts, any error can be considered as not matched
+			if err != nil {
+				return nil, []string{fmt.Sprintf("CODEOWNERS rule %q times out for matching against path %q", rule.Rule.String(), path)}
+			}
+			ruleMatched := patternMatched != rule.Negative
+			if !ruleMatched {
+				continue
+			}
+			if rule.Section == "" {
+				selected[rule] = true
+			} else {
+				sections[rule.Section] = rule
+			}
+		}
+		for _, rule := range sections {
+			selected[rule] = true
+		}
+	}
+	matching := make([]*issues_model.CodeOwnerRule, 0, len(selected))
+	for _, rule := range rules {
+		if selected[rule] {
+			matching = append(matching, rule)
+		}
+	}
+	return matching, nil
 }
 
 func HasAllRequiredCodeownerReviews(ctx context.Context, pb *git_model.ProtectedBranch, pr *issues_model.PullRequest) bool {
@@ -279,8 +327,27 @@ func pullRequestCodeOwnersReview(ctx context.Context, pr *issues_model.PullReque
 	issue := pr.Issue
 	uniqUsers := make(map[int64]*user_model.User)
 	uniqTeams := make(map[string]*org_model.Team)
+	// TODO: should a user in a team be notified if the user themselves doesn't accept notification? Leave the decisions to the future ....
+	watchingPullRequests := make(map[int64]bool)
 	for _, rule := range matchingRules {
+		if !rule.ReviewRequest.ValueOrDefault(true) {
+			continue
+		}
 		for _, u := range rule.Users {
+			if !rule.ReviewRequest.Has() && uniqUsers[u.ID] == nil {
+				watching, ok := watchingPullRequests[u.ID]
+				if !ok {
+					watch, err := repo_model.GetWatch(ctx, u.ID, issue.RepoID)
+					if err != nil {
+						return nil, err
+					}
+					watching = watch.IsWatching() && watch.IncludePullRequests
+					watchingPullRequests[u.ID] = watching
+				}
+				if !watching {
+					continue
+				}
+			}
 			uniqUsers[u.ID] = u
 		}
 		for _, t := range rule.Teams {

services/issue/pull_test.go

@@ -4,13 +4,16 @@
 package issue
 
 import (
+	"strings"
 	"testing"
 
 	"gitea.dev/models/db"
 	issues_model "gitea.dev/models/issues"
 	org_model "gitea.dev/models/organization"
+	repo_model "gitea.dev/models/repo"
 	"gitea.dev/models/unittest"
 	user_model "gitea.dev/models/user"
+	"gitea.dev/modules/optional"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -30,8 +33,8 @@ func TestPullRequestCodeOwnersReview(t *testing.T) {
 	team := unittest.AssertExistsAndLoadBean(t, &org_model.Team{ID: 2})
 
 	rules := []*issues_model.CodeOwnerRule{
-		{Users: []*user_model.User{poster, reviewer, requestedReviewer}, Teams: []*org_model.Team{team}},
-		{Users: []*user_model.User{reviewer}, Teams: []*org_model.Team{team}},
+		{Users: []*user_model.User{poster, reviewer, requestedReviewer}, Teams: []*org_model.Team{team}, ReviewRequest: optional.Some(true)},
+		{Users: []*user_model.User{reviewer}, Teams: []*org_model.Team{team}, ReviewRequest: optional.Some(true)},
 	}
 
 	for _, tc := range []struct {
@@ -63,7 +66,12 @@ func TestPullRequestCodeOwnersReview(t *testing.T) {
 			before, err := db.GetEngine(ctx).Count(&issues_model.Review{IssueID: pr.IssueID})
 			require.NoError(t, err)
 
-			notifiers, err := pullRequestCodeOwnersReview(ctx, pr, rules)
+			disabled := []*issues_model.CodeOwnerRule{{Users: []*user_model.User{reviewer}, Teams: []*org_model.Team{team}, ReviewRequest: optional.Some(false)}}
+			notifiers, err := pullRequestCodeOwnersReview(ctx, pr, disabled)
+			require.NoError(t, err)
+			assert.Empty(t, notifiers)
+
+			notifiers, err = pullRequestCodeOwnersReview(ctx, pr, rules)
 			require.NoError(t, err)
 
 			var users, teams int
@@ -95,3 +103,81 @@ func TestPullRequestCodeOwnersReview(t *testing.T) {
 		})
 	}
 }
+
+func TestMatchCodeOwnerRules(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	rules, warnings := issues_model.GetCodeOwnersFromContent(t.Context(), strings.TrimSpace(`
+*.md @user1
+[Docs] @user5
+*.md
+README.md @user4
+[Docs] @user2
+other.md
+[Independent] @user1
+*.md
+`))
+	require.Empty(t, warnings)
+	for _, tc := range []struct {
+		paths    []string
+		lineNums []int
+	}{
+		{[]string{"README.md"}, []int{1, 4, 8}},
+		{[]string{"README.md", "guide.md"}, []int{1, 3, 4, 8}},
+		{[]string{"other.md"}, []int{1, 6, 8}},
+		{[]string{"file.go"}, nil},
+	} {
+		t.Run(strings.Join(tc.paths, ","), func(t *testing.T) {
+			matching, warnings := MatchCodeOwnerRules(rules, tc.paths)
+			assert.Empty(t, warnings)
+			var lineNums []int
+			for _, rule := range matching {
+				lineNums = append(lineNums, rule.LineNum)
+			}
+			assert.Equal(t, tc.lineNums, lineNums)
+		})
+	}
+}
+
+func TestPullRequestCodeOwnersReviewWatch(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	pr := unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{IssueID: 12})
+	require.NoError(t, pr.LoadIssue(t.Context()))
+	require.NoError(t, pr.LoadBaseRepo(t.Context()))
+	require.NoError(t, pr.Issue.LoadRepo(t.Context()))
+	reviewer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 4})
+	for _, tc := range []struct {
+		name                string
+		mode                repo_model.WatchMode
+		includePullRequests bool
+		content             string
+		want                bool
+	}{
+		{"not watching", repo_model.WatchModeNone, true, "*.md @user4", false},
+		{"ignoring", repo_model.WatchModeDont, true, "*.md @user4", false},
+		{"watching pull requests", repo_model.WatchModeCustom, true, "*.md @user4", true},
+		{"not watching pull requests", repo_model.WatchModeCustom, false, "*.md @user4", false},
+		{"explicit true without watch", repo_model.WatchModeNone, false, "*.md @user4 ## review-request=true", true},
+		{"explicit true overrides opt out", repo_model.WatchModeCustom, false, "*.md @user4 ## review-request=true", true},
+		{"explicit false overrides watch", repo_model.WatchModeCustom, true, "*.md @user4 ## review-request=false", false},
+		{"explicit true on another rule", repo_model.WatchModeCustom, false, "*.md @user4\n*.js @user4 ## review-request=true", true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, committer, err := db.TxContext(t.Context())
+			require.NoError(t, err)
+			defer committer.Close()
+			require.NoError(t, repo_model.WatchRepoWithOptions(ctx, reviewer, pr.BaseRepo, repo_model.WatchOptions{
+				Mode: tc.mode, WatchPullRequests: tc.includePullRequests, WatchIssues: true,
+			}))
+			rules, warnings := issues_model.GetCodeOwnersFromContent(ctx, tc.content)
+			require.Empty(t, warnings)
+			notifiers, err := pullRequestCodeOwnersReview(ctx, pr, rules)
+			require.NoError(t, err)
+			if tc.want {
+				require.Len(t, notifiers, 1)
+				assert.Equal(t, reviewer.ID, notifiers[0].Reviewer.ID)
+			} else {
+				assert.Empty(t, notifiers)
+			}
+		})
+	}
+}

templates/repo/view_file.tmpl

@@ -23,6 +23,14 @@
 				{{end}}
 			{{end}}
 		</div>
+		{{if .FileCodeOwners}}
+		<div class="file-codeowners ui segment flex-text-block tw-flex-wrap">
+			{{svg "octicon-shield-check" 16}} <span>{{ctx.Locale.Tr "repo.codeowners"}}</span>
+			{{range $one := .FileCodeOwners}}
+				<a href="{{$one.CodeOwnerLink}}">{{$one.CodeOwnerName}}</a>
+			{{end}}
+		</div>
+		{{end}}
 	{{end}}
 
 	<h4 class="file-header ui top attached header flex-left-right">

tests/integration/pull_review_test.go

@@ -94,6 +94,12 @@ func TestPullView_CodeOwner(t *testing.T) {
 		}, true)
 		assert.NoError(t, err)
 
+		for _, reviewer := range []*user_model.User{user5, user8} {
+			require.NoError(t, repo_model.WatchRepoWithOptions(t.Context(), reviewer, repo, repo_model.WatchOptions{
+				Mode: repo_model.WatchModeCustom, WatchPullRequests: true,
+			}))
+		}
+
 		// create code owner branch protection
 		protectBranch := git_model.ProtectedBranch{
 			BlockOnCodeownerReviews: true,
@@ -118,6 +124,31 @@ func TestPullView_CodeOwner(t *testing.T) {
 		})
 		assert.NoError(t, err)
 
+		t.Run("File owners", func(t *testing.T) {
+			session := loginUser(t, "user2")
+			resp := session.MakeRequest(t, NewRequest(t, "GET", "/user2/test_codeowner/src/branch/master/README.md"), http.StatusOK)
+			doc := NewHTMLParser(t, resp.Body)
+			assert.Equal(t, "@user5", doc.Find(".file-codeowners a").Text())
+
+			_, err := files_service.ChangeRepoFiles(t.Context(), repo, user2, &files_service.ChangeRepoFilesOptions{
+				OldBranch: repo.DefaultBranch,
+				NewBranch: "file-owners",
+				Files: []*files_service.ChangeRepoFile{{
+					Operation:     "update",
+					TreePath:      "CODEOWNERS",
+					ContentReader: strings.NewReader("## review-request=false\n[Docs] @user8 @org3/team1\n*.md\n"),
+				}},
+			})
+			require.NoError(t, err)
+			resp = session.MakeRequest(t, NewRequest(t, "GET", "/user2/test_codeowner/src/branch/file-owners/README.md"), http.StatusOK)
+			doc = NewHTMLParser(t, resp.Body)
+			assert.Equal(t, "@user8", doc.Find(".file-codeowners a[href='/user8']").Text())
+			assert.Equal(t, "@org3/team1", doc.Find(".file-codeowners a[href='/org3/teams/team1']").Text())
+			resp = session.MakeRequest(t, NewRequest(t, "GET", "/user2/test_codeowner/src/branch/file-owners/CODEOWNERS"), http.StatusOK)
+			doc = NewHTMLParser(t, resp.Body)
+			assert.Zero(t, doc.Find(".file-codeowners").Length())
+		})
+
 		readmeBranchOptions := func(branch, content string) *files_service.ChangeRepoFilesOptions {
 			return &files_service.ChangeRepoFilesOptions{
 				NewBranch: branch,