diff --git a/claudetool/bash.go b/claudetool/bash.go
index 9f998ea58a7888a351613be04f25da7e48883009..7e3bfd5bc6800388ac644da5ea6d35c18c9febb1 100644
--- a/claudetool/bash.go
+++ b/claudetool/bash.go
@@ -96,6 +96,15 @@ func (b *BashTool) getWorkingDir() string {
 	return b.WorkingDir.Get()
 }
 
+// isNoTrailerSet checks if user has disabled co-author trailer via git config.
+func (b *BashTool) isNoTrailerSet() bool {
+	out, err := exec.Command("git", "config", "--get", "shelley.no-trailer").Output()
+	if err != nil {
+		return false
+	}
+	return strings.TrimSpace(string(out)) == "true"
+}
+
 const (
 	bashName        = "bash"
 	bashDescription = `Executes shell commands via bash -c, returning combined stdout/stderr.
@@ -207,8 +216,10 @@ func (b *BashTool) Run(ctx context.Context, m json.RawMessage) llm.ToolOut {
 		}
 	}
 
-	// Add co-author trailer to git commits
-	req.Command = bashkit.AddCoauthorTrailer(req.Command, "Co-authored-by: Shelley <shelley@exe.dev>")
+	// Add co-author trailer to git commits unless user has disabled it
+	if !b.isNoTrailerSet() {
+		req.Command = bashkit.AddCoauthorTrailer(req.Command, "Co-authored-by: Shelley <shelley@exe.dev>")
+	}
 
 	timeout := req.timeout(b.Timeouts)
 
diff --git a/claudetool/bash_test.go b/claudetool/bash_test.go
index 4346a1b5b990a0201ca95702b165ecd5c3c0b36a..3b44122c1e3f05d32e4bf034d0a7c479ed950fd4 100644
--- a/claudetool/bash_test.go
+++ b/claudetool/bash_test.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 	"syscall"
@@ -721,3 +722,41 @@ func waitForProcessDeath(t *testing.T, pid int) {
 		}
 	}
 }
+
+func TestIsNoTrailerSet(t *testing.T) {
+	bashTool := &BashTool{WorkingDir: NewMutableWorkingDir("/")}
+
+	// Test when config is not set (default)
+	t.Run("Default No Config", func(t *testing.T) {
+		if bashTool.isNoTrailerSet() {
+			t.Error("Expected isNoTrailerSet() to be false when not configured")
+		}
+	})
+
+	// Test when config is set to true
+	t.Run("Config Set True", func(t *testing.T) {
+		// Set the global config
+		cmd := exec.Command("git", "config", "--global", "shelley.no-trailer", "true")
+		if err := cmd.Run(); err != nil {
+			t.Skipf("Could not set git config: %v", err)
+		}
+		defer exec.Command("git", "config", "--global", "--unset", "shelley.no-trailer").Run()
+
+		if !bashTool.isNoTrailerSet() {
+			t.Error("Expected isNoTrailerSet() to be true when shelley.no-trailer=true")
+		}
+	})
+
+	// Test when config is set to false
+	t.Run("Config Set False", func(t *testing.T) {
+		cmd := exec.Command("git", "config", "--global", "shelley.no-trailer", "false")
+		if err := cmd.Run(); err != nil {
+			t.Skipf("Could not set git config: %v", err)
+		}
+		defer exec.Command("git", "config", "--global", "--unset", "shelley.no-trailer").Run()
+
+		if bashTool.isNoTrailerSet() {
+			t.Error("Expected isNoTrailerSet() to be false when shelley.no-trailer=false")
+		}
+	})
+}