Pull git-flow prefix parsing into a config-level helper

Lift the inline parsing in FinishCmdObj into parseGitFlowPrefixMap on
ConfigCommands. The caller now does a direct map lookup against the
parsed prefix → branchType map instead of iterating the raw config
output and suffix-matching. This is preparation for adding git-flow-next
support, which needs to merge a second config schema into the same map.

One incidental change: a branch name without a slash now returns
NotAGitFlowBranch immediately, rather than falling through the
line loop with an empty suffix. Previously a configured
gitflow.prefix.X whose value happened to equal the entire branch
name could match — never a useful outcome.

pkg/commands/git_commands/config.go

@@ -1,6 +1,7 @@
 package git_commands
 
 import (
+	"regexp"
 	"strings"
 
 	"github.com/jesseduffield/lazygit/pkg/commands/git_config"
@@ -116,6 +117,42 @@ func (self *ConfigCommands) GetGitFlowPrefixes() string {
 	return self.gitConfig.GetGeneral("--local --get-regexp gitflow.prefix")
 }
 
+// parseGitFlowPrefixMap parses git-flow config output into a prefix → branchType map.
+// Line format: "gitflow.prefix.<type> <prefix>". Prefixes are normalized to end in "/".
+func parseGitFlowPrefixMap(legacyOutput string) map[string]string {
+	legacyRegexp := regexp.MustCompile(`gitflow\.prefix\.(\S+)\s+(.*)`)
+	prefixToType := make(map[string]string)
+	for line := range strings.SplitSeq(legacyOutput, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		if m := legacyRegexp.FindStringSubmatch(line); len(m) == 3 {
+			prefix := normalizeGitFlowPrefix(m[2])
+			if prefix == "" {
+				continue
+			}
+			prefixToType[prefix] = m[1]
+		}
+	}
+	return prefixToType
+}
+
+func normalizeGitFlowPrefix(prefix string) string {
+	prefix = strings.TrimSpace(prefix)
+	if prefix == "" {
+		return ""
+	}
+	if !strings.HasSuffix(prefix, "/") {
+		return prefix + "/"
+	}
+	return prefix
+}
+
+func (self *ConfigCommands) GetGitFlowPrefixMap() map[string]string {
+	return parseGitFlowPrefixMap(self.GetGitFlowPrefixes())
+}
+
 func (self *ConfigCommands) GetCoreCommentChar() byte {
 	if commentCharStr := self.gitConfig.Get("core.commentChar"); len(commentCharStr) == 1 {
 		return commentCharStr[0]

pkg/commands/git_commands/config_test.go

@@ -0,0 +1,94 @@
+package git_commands
+
+import (
+	"testing"
+
+	"github.com/jesseduffield/lazygit/pkg/commands/git_config"
+	"github.com/jesseduffield/lazygit/pkg/common"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParseGitFlowPrefixMap(t *testing.T) {
+	type scenario struct {
+		testName     string
+		legacyOutput string
+		expected     map[string]string
+	}
+	scenarios := []scenario{
+		{
+			testName:     "empty input",
+			legacyOutput: "",
+			expected:     map[string]string{},
+		},
+		{
+			testName:     "feature and hotfix",
+			legacyOutput: "gitflow.prefix.feature feature/\ngitflow.prefix.hotfix hotfix/",
+			expected:     map[string]string{"feature/": "feature", "hotfix/": "hotfix"},
+		},
+		{
+			testName:     "prefix normalized with trailing slash",
+			legacyOutput: "gitflow.prefix.feature feature",
+			expected:     map[string]string{"feature/": "feature"},
+		},
+		{
+			testName:     "malformed lines skipped",
+			legacyOutput: "gitflow.prefix.feature feature/\nnot-a-valid-line\ngitflow.prefix.hotfix hotfix/",
+			expected:     map[string]string{"feature/": "feature", "hotfix/": "hotfix"},
+		},
+		{
+			testName:     "blank lines and whitespace ignored",
+			legacyOutput: "  \n  gitflow.prefix.feature feature/  \n  \n  ",
+			expected:     map[string]string{"feature/": "feature"},
+		},
+	}
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			got := parseGitFlowPrefixMap(s.legacyOutput)
+			assert.Equal(t, s.expected, got)
+		})
+	}
+}
+
+func TestGetGitFlowPrefixMap(t *testing.T) {
+	type scenario struct {
+		testName               string
+		gitConfigMockResponses map[string]string
+		expected               map[string]string
+	}
+	scenarios := []scenario{
+		{
+			testName:               "empty when no config",
+			gitConfigMockResponses: nil,
+			expected:               map[string]string{},
+		},
+		{
+			testName: "correct map from legacy output",
+			gitConfigMockResponses: map[string]string{
+				"--local --get-regexp gitflow.prefix": "gitflow.prefix.feature feature/\ngitflow.prefix.hotfix hotfix/",
+			},
+			expected: map[string]string{"feature/": "feature", "hotfix/": "hotfix"},
+		},
+		{
+			testName: "prefix normalized with trailing slash",
+			gitConfigMockResponses: map[string]string{
+				"--local --get-regexp gitflow.prefix": "gitflow.prefix.feature feature",
+			},
+			expected: map[string]string{"feature/": "feature"},
+		},
+		{
+			testName: "malformed lines skipped",
+			gitConfigMockResponses: map[string]string{
+				"--local --get-regexp gitflow.prefix": "gitflow.prefix.feature feature/\nnot-a-valid-line\n",
+			},
+			expected: map[string]string{"feature/": "feature"},
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			config := NewConfigCommands(common.NewDummyCommon(), git_config.NewFakeGitConfig(s.gitConfigMockResponses))
+			got := config.GetGitFlowPrefixMap()
+			assert.Equal(t, s.expected, got)
+		})
+	}
+}

pkg/commands/git_commands/flow.go

@@ -1,7 +1,6 @@
 package git_commands
 
 import (
-	"regexp"
 	"strings"
 
 	"github.com/go-errors/errors"
@@ -25,26 +24,15 @@ func (self *FlowCommands) GitFlowEnabled() bool {
 }
 
 func (self *FlowCommands) FinishCmdObj(branchName string) (*oscommands.CmdObj, error) {
-	prefixes := self.config.GetGitFlowPrefixes()
+	prefixMap := self.config.GetGitFlowPrefixMap()
 
-	// need to find out what kind of branch this is
-	prefix := strings.SplitAfterN(branchName, "/", 2)[0]
-	suffix := strings.Replace(branchName, prefix, "", 1)
-
-	branchType := ""
-	for line := range strings.SplitSeq(strings.TrimSpace(prefixes), "\n") {
-		if strings.HasPrefix(line, "gitflow.prefix.") && strings.HasSuffix(line, prefix) {
-
-			regex := regexp.MustCompile("gitflow.prefix.([^ ]*) .*")
-			matches := regex.FindAllStringSubmatch(line, 1)
-
-			if len(matches) > 0 && len(matches[0]) > 1 {
-				branchType = matches[0][1]
-				break
-			}
-		}
+	prefixPart, suffix, ok := strings.Cut(branchName, "/")
+	if !ok || prefixPart == "" || suffix == "" {
+		return nil, errors.New(self.Tr.NotAGitFlowBranch)
 	}
+	prefix := prefixPart + "/"
 
+	branchType := prefixMap[prefix]
 	if branchType == "" {
 		return nil, errors.New(self.Tr.NotAGitFlowBranch)
 	}