feat(repl): add OSC 7 terminal cwd tracking

AGENTS.md

@@ -15,6 +15,10 @@ model exampleModel {
 }
 ```
 
+## Test-Driven Development
+
+Always use TDD when developing new features. Write tests first based on the expected behavior (e.g., spec, protocol, or requirements), then write the implementation to make them pass. Writing tests after the implementation risks asserting what the code does rather than what it should do, which lets bugs slip through.
+
 ## Testing the binary
 
 If you need to build the gsh binary for testing, you can just run `make build` or a custom build command outputting to `./bin/gsh`.

internal/repl/osc.go

@@ -0,0 +1,23 @@
+package repl
+
+import (
+	"fmt"
+	"io"
+	"net/url"
+	"strings"
+)
+
+// emitOSC7 writes an OSC 7 escape sequence to inform the terminal of the
+// current working directory. This allows terminal emulators (Terminal.app,
+// iTerm2, etc.) to open new tabs/windows in the same directory.
+// Format: ESC ] 7 ; file://HOSTNAME/url-encoded-path ESC \
+func emitOSC7(w io.Writer, hostname, dir string) {
+	// Encode each path segment individually to preserve '/' separators.
+	// url.PathEscape encodes '/' to '%2F' which breaks the file URL.
+	segments := strings.Split(dir, "/")
+	for i, seg := range segments {
+		segments[i] = url.PathEscape(seg)
+	}
+	encodedPath := strings.Join(segments, "/")
+	fmt.Fprintf(w, "\033]7;file://%s%s\033\\", hostname, encodedPath)
+}

internal/repl/osc_test.go

@@ -0,0 +1,51 @@
+package repl
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestEmitOSC7(t *testing.T) {
+	tests := []struct {
+		name     string
+		hostname string
+		dir      string
+		expected string
+	}{
+		{
+			name:     "normal path",
+			hostname: "myhost",
+			dir:      "/Users/test/projects",
+			expected: "\033]7;file://myhost/Users/test/projects\033\\",
+		},
+		{
+			name:     "path with spaces",
+			hostname: "myhost",
+			dir:      "/Users/test/my projects",
+			expected: "\033]7;file://myhost/Users/test/my%20projects\033\\",
+		},
+		{
+			name:     "path with hash",
+			hostname: "myhost",
+			dir:      "/Users/test/project#1",
+			expected: "\033]7;file://myhost/Users/test/project%231\033\\",
+		},
+		{
+			name:     "empty hostname",
+			hostname: "",
+			dir:      "/Users/test",
+			expected: "\033]7;file:///Users/test\033\\",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			emitOSC7(&buf, tt.hostname, tt.dir)
+			got := buf.String()
+			if got != tt.expected {
+				t.Errorf("emitOSC7(%q, %q) = %q, want %q", tt.hostname, tt.dir, got, tt.expected)
+			}
+		})
+	}
+}

internal/repl/repl.go

@@ -263,6 +263,9 @@ func (r *REPL) setSigintChannelFactory(factory func() (chan os.Signal, func()))
 func (r *REPL) Run(ctx context.Context) error {
 	r.logger.Info("starting REPL")
 
+	// Cache hostname for OSC 7 escape sequences (terminal CWD tracking)
+	hostname, _ := os.Hostname()
+
 	// Emit repl.ready event (welcome screen is handled by event handler in defaults/events/repl.gsh)
 	r.executor.Interpreter().EmitEvent(interpreter.EventReplReady, interpreter.CreateReplReadyContext())
 
@@ -292,6 +295,12 @@ func (r *REPL) Run(ctx context.Context) error {
 		default:
 		}
 
+		// Emit OSC 7 to tell the terminal the current working directory
+		// (enables new tabs/windows to open in the same directory)
+		if dir := r.executor.GetPwd(); dir != "" && term.IsTerminal(int(os.Stdout.Fd())) {
+			emitOSC7(os.Stdout, hostname, dir)
+		}
+
 		// Get prompt - emits repl.prompt event internally
 		prompt := r.getPrompt()