diff --git a/cmd/byre/run.go b/cmd/byre/run.go
index fed7139..2f75865 100644
--- a/cmd/byre/run.go
+++ b/cmd/byre/run.go
@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"g.fc.run/ai/byre/internal/claude"
+	"g.fc.run/ai/byre/internal/git"
 )
 
 func runCmd(args []string) {
@@ -27,10 +28,9 @@ func runCmd(args []string) {
 
 	ctx := context.Background()
 	s, err := claude.Start(ctx, claude.Options{
-		Cwd:      dir,
-		Resume:   *resume,
-		GitName:  gitConfig(dir, "user.name"),
-		GitEmail: gitConfig(dir, "user.email"),
+		Cwd:    dir,
+		Resume: *resume,
+		Env:    git.IdentityEnv(gitConfig(dir, "user.name"), gitConfig(dir, "user.email")),
 	})
 	if err != nil {
 		fatal("start claude", "err", err)
diff --git a/internal/agents/manager.go b/internal/agents/manager.go
index 3d13e23..3ea076c 100644
--- a/internal/agents/manager.go
+++ b/internal/agents/manager.go
@@ -949,6 +949,7 @@ func (m *Manager) startLive(ctx context.Context, sess api.AgentSession, task api
 		tools = append(m.leadTools(l), m.readKnowledgeTool())
 		env = nil
 	}
+	env = append(git.IdentityEnv(l.gitName, l.gitEmail), env...)
 	servers := []*mcp.Server{{Name: "byre", Version: "0.0.0", Tools: tools}}
 
 	sctx, cancel := context.WithTimeout(ctx, 60*time.Second)
diff --git a/internal/agents/mergein.go b/internal/agents/mergein.go
index a6e5d96..247bd55 100644
--- a/internal/agents/mergein.go
+++ b/internal/agents/mergein.go
@@ -514,12 +514,7 @@ func (m *Manager) squashAndClose(ctx context.Context, taskID, login string) erro
 		return err
 	}
 
-	env := []string{
-		"GIT_AUTHOR_NAME=" + user.GitName,
-		"GIT_AUTHOR_EMAIL=" + user.GitEmail,
-		"GIT_COMMITTER_NAME=" + user.GitName,
-		"GIT_COMMITTER_EMAIL=" + user.GitEmail,
-	}
+	env := git.IdentityEnv(user.GitName, user.GitEmail)
 	commit, err := git.SquashCommit(project.RepoPath, task.WorktreePath, project.DefaultBranch, squashMessage(task.MergeTitle, coAuthors), env, m.signer(ctx, user))
 	if err != nil {
 		return err
diff --git a/internal/agents/mergemain.go b/internal/agents/mergemain.go
index 7830fcb..588dceb 100644
--- a/internal/agents/mergemain.go
+++ b/internal/agents/mergemain.go
@@ -123,12 +123,7 @@ func (m *Manager) pushToMain(ctx context.Context, l *live, task api.Task, projec
 	if err != nil {
 		return "", err
 	}
-	env := []string{
-		"GIT_AUTHOR_NAME=" + user.GitName,
-		"GIT_AUTHOR_EMAIL=" + user.GitEmail,
-		"GIT_COMMITTER_NAME=" + user.GitName,
-		"GIT_COMMITTER_EMAIL=" + user.GitEmail,
-	}
+	env := git.IdentityEnv(user.GitName, user.GitEmail)
 	commit, err := git.SquashCommit(project.RepoPath, l.dir, project.DefaultBranch, squashMessage(title, coAuthors), env, m.signer(ctx, user))
 	conflict := &git.ConflictError{}
 	if errors.As(err, &conflict) {
diff --git a/internal/agents/process.go b/internal/agents/process.go
index 1c91529..3afe0cb 100644
--- a/internal/agents/process.go
+++ b/internal/agents/process.go
@@ -88,8 +88,6 @@ func (m *Manager) startClaude(ctx context.Context, sess api.AgentSession, l *liv
 	opts := claude.Options{
 		Cwd:        l.dir,
 		Model:      sess.Model,
-		GitName:    l.gitName,
-		GitEmail:   l.gitEmail,
 		Env:        env,
 		Guidance:   g + l.notes,
 		MCPServers: servers,
@@ -169,8 +167,6 @@ func (m *Manager) startCodex(ctx context.Context, sess api.AgentSession, l *live
 	opts := codex.Options{
 		Cwd:        l.dir,
 		Model:      sess.Model,
-		GitName:    l.gitName,
-		GitEmail:   l.gitEmail,
 		Env:        append(env, "CODEX_HOME="+m.codexHome),
 		Guidance:   g + l.notes,
 		Reminder:   g,
@@ -247,8 +243,6 @@ func (m *Manager) startAntigravity(ctx context.Context, sess api.AgentSession, l
 		Cwd:        l.dir,
 		Model:      sess.Model,
 		Resume:     sess.VendorSessionId,
-		GitName:    l.gitName,
-		GitEmail:   l.gitEmail,
 		Env:        env,
 		Guidance:   g,
 		Notes:      strings.TrimSpace(l.notes),
diff --git a/internal/agents/snapshots.go b/internal/agents/snapshots.go
index 235e08b..ebbcceb 100644
--- a/internal/agents/snapshots.go
+++ b/internal/agents/snapshots.go
@@ -155,12 +155,7 @@ func (m *Manager) takeSnapshot(ctx context.Context, t snapTarget, trigger api.Sn
 	}
 
 	n := last.N + 1
-	commit, err := git.CommitSnapshot(t.dir, tree, git.SnapshotRef(t.taskID, n), fmt.Sprintf("byre snapshot %d (%s)", n, trigger), []string{
-		"GIT_AUTHOR_NAME=" + t.gitName,
-		"GIT_AUTHOR_EMAIL=" + t.gitEmail,
-		"GIT_COMMITTER_NAME=" + t.gitName,
-		"GIT_COMMITTER_EMAIL=" + t.gitEmail,
-	})
+	commit, err := git.CommitSnapshot(t.dir, tree, git.SnapshotRef(t.taskID, n), fmt.Sprintf("byre snapshot %d (%s)", n, trigger), git.IdentityEnv(t.gitName, t.gitEmail))
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/antigravity/session.go b/internal/antigravity/session.go
index cad830b..9cf61af 100644
--- a/internal/antigravity/session.go
+++ b/internal/antigravity/session.go
@@ -33,8 +33,6 @@ type Options struct {
 	Cwd        string
 	Model      string
 	Resume     string
-	GitName    string
-	GitEmail   string
 	Env        []string
 	Guidance   string
 	Notes      string
@@ -327,13 +325,7 @@ func (s *Session) spawnLocked() error {
 	cmd := procgroup.Command("agy", args...)
 	cmd.Dir = s.opts.Cwd
 	cmd.Stderr = os.Stderr
-	cmd.Env = append(os.Environ(),
-		"GIT_AUTHOR_NAME="+s.opts.GitName,
-		"GIT_AUTHOR_EMAIL="+s.opts.GitEmail,
-		"GIT_COMMITTER_NAME="+s.opts.GitName,
-		"GIT_COMMITTER_EMAIL="+s.opts.GitEmail,
-	)
-	cmd.Env = append(cmd.Env, s.opts.Env...)
+	cmd.Env = append(os.Environ(), s.opts.Env...)
 
 	stdin, err := cmd.StdinPipe()
 	if err != nil {
diff --git a/internal/claude/session.go b/internal/claude/session.go
index df85d3f..dc7d865 100644
--- a/internal/claude/session.go
+++ b/internal/claude/session.go
@@ -35,8 +35,6 @@ type Options struct {
 	Resume      string
 	ResumeAt    string
 	ForkSession bool
-	GitName     string
-	GitEmail    string
 	Env         []string
 	Guidance    string
 	Hooks       map[string][]HookMatcher
@@ -370,10 +368,6 @@ func buildEnv(opts Options) []string {
 	env = append(env,
 		"CLAUDE_CODE_ENTRYPOINT=sdk-go",
 		"CLAUDE_CODE_DISABLE_AUTOUPDATER=1",
-		"GIT_AUTHOR_NAME="+opts.GitName,
-		"GIT_AUTHOR_EMAIL="+opts.GitEmail,
-		"GIT_COMMITTER_NAME="+opts.GitName,
-		"GIT_COMMITTER_EMAIL="+opts.GitEmail,
 	)
 	return append(env, opts.Env...)
 }
diff --git a/internal/codex/session.go b/internal/codex/session.go
index 26fdded..5b49daf 100644
--- a/internal/codex/session.go
+++ b/internal/codex/session.go
@@ -27,8 +27,6 @@ type Options struct {
 	Resume     string
 	ForkFrom   string
 	ForkAt     string
-	GitName    string
-	GitEmail   string
 	Env        []string
 	Guidance   string
 	Reminder   string
@@ -158,7 +156,7 @@ func spawn(opts Options) (*Session, error) {
 	cmd := procgroup.Command("codex", "app-server", "-c", "check_for_update_on_startup=false")
 	cmd.Dir = opts.Cwd
 	cmd.Stderr = os.Stderr
-	cmd.Env = buildEnv(opts)
+	cmd.Env = append(os.Environ(), opts.Env...)
 
 	stdinR, stdin, err := os.Pipe()
 	if err != nil {
@@ -321,16 +319,6 @@ func (s *Session) setThread(id string) {
 	s.stateMu.Unlock()
 }
 
-func buildEnv(opts Options) []string {
-	env := append(os.Environ(),
-		"GIT_AUTHOR_NAME="+opts.GitName,
-		"GIT_AUTHOR_EMAIL="+opts.GitEmail,
-		"GIT_COMMITTER_NAME="+opts.GitName,
-		"GIT_COMMITTER_EMAIL="+opts.GitEmail,
-	)
-	return append(env, opts.Env...)
-}
-
 func (s *Session) Events() <-chan Event {
 	return s.events
 }
diff --git a/internal/git/git.go b/internal/git/git.go
index f01e5ed..94014a7 100644
--- a/internal/git/git.go
+++ b/internal/git/git.go
@@ -366,12 +366,7 @@ func CommitAll(dir, message, name, email string) (string, error) {
 		return "", nil
 	}
 
-	env := []string{
-		"GIT_AUTHOR_NAME=" + name,
-		"GIT_AUTHOR_EMAIL=" + email,
-		"GIT_COMMITTER_NAME=" + name,
-		"GIT_COMMITTER_EMAIL=" + email,
-	}
+	env := IdentityEnv(name, email)
 	_, err = runEnv(dir, env, "add", "--all")
 	if err != nil {
 		return "", err
@@ -384,12 +379,7 @@ func CommitAll(dir, message, name, email string) (string, error) {
 }
 
 func Merge(dir, rev, message, name, email string) error {
-	env := []string{
-		"GIT_AUTHOR_NAME=" + name,
-		"GIT_AUTHOR_EMAIL=" + email,
-		"GIT_COMMITTER_NAME=" + name,
-		"GIT_COMMITTER_EMAIL=" + email,
-	}
+	env := IdentityEnv(name, email)
 	_, err := runEnv(dir, env, "merge", "--no-ff", "--quiet", "--message", message, rev)
 	return err
 }
diff --git a/internal/git/identity.go b/internal/git/identity.go
new file mode 100644
index 0000000..0bf8a8b
--- /dev/null
+++ b/internal/git/identity.go
@@ -0,0 +1,10 @@
+package git
+
+func IdentityEnv(name, email string) []string {
+	return []string{
+		"GIT_AUTHOR_NAME=" + name,
+		"GIT_AUTHOR_EMAIL=" + email,
+		"GIT_COMMITTER_NAME=" + name,
+		"GIT_COMMITTER_EMAIL=" + email,
+	}
+}
diff --git a/internal/git/rename.go b/internal/git/rename.go
index f84b1bc..13a84cc 100644
--- a/internal/git/rename.go
+++ b/internal/git/rename.go
@@ -136,7 +136,7 @@ func RewriteNotes(repo string, rewrite func(string) string) error {
 		return err
 	}
 	name, email, _ := strings.Cut(who, "\n")
-	env := []string{"GIT_AUTHOR_NAME=" + name, "GIT_AUTHOR_EMAIL=" + email, "GIT_COMMITTER_NAME=" + name, "GIT_COMMITTER_EMAIL=" + email}
+	env := IdentityEnv(name, email)
 	commit, err := runEnv(repo, env, "commit-tree", "-p", parent, "-m", "Rewrite byre ids in notes", tree)
 	if err != nil {
 		return err