report the working directory to the terminal with OSC 7

Before each prompt gosh sends ESC ] 7 ; file://host/path BEL (host and
path percent-encoded), so terminals like GNOME Terminal open new tabs
and windows in the directory of the shell instead of the one gosh was
started in. Nothing is sent if stdout is not a terminal or TERM=dumb.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -59,6 +59,8 @@ Features:
     GOSH_COLORS='user=1;33:path=36' (keys user, root, path, error; values
     are ANSI SGR codes, empty = no color); disabled with $NO_COLOR,
     TERM=dumb or when output is not a terminal
+  - Reports the working directory to the terminal (OSC 7) before each
+    prompt, so new tabs/windows open in the same directory
   - Variables: name=value sets a variable (like set), name=value command
     sets it only for that command; the value is not split or expanded as
     a pattern

main.go

@@ -795,6 +795,49 @@ func useColor() bool {
 	return readline.IsTerminal(int(os.Stdout.Fd()))
 }
 
+// reportCwd tells the terminal the current working directory with the OSC 7
+// escape sequence, so that new tabs or windows open in the same directory
+// (VTE terminals like GNOME Terminal, kitty, WezTerm, foot, iTerm2, ...).
+// Terminals without support ignore it. Nothing is written if stdout is not a
+// terminal or TERM is "dumb".
+func reportCwd() {
+	if os.Getenv("TERM") == "dumb" || !readline.IsTerminal(int(os.Stdout.Fd())) {
+		return
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		return
+	}
+	hostname, _ := os.Hostname()
+	fmt.Fprint(os.Stdout, osc7Sequence(hostname, wd))
+}
+
+// osc7Sequence returns ESC ] 7 ; file://host/path BEL. Host and path are
+// percent-encoded, so control characters in a directory name cannot end the
+// sequence early or inject other escape sequences.
+func osc7Sequence(hostname, dir string) string {
+	return "\x1b]7;file://" + percentEncode(hostname, false) + percentEncode(dir, true) + "\a"
+}
+
+// percentEncode encodes every byte except unreserved URI characters (and '/'
+// if keepSlash) as %XX.
+func percentEncode(s string, keepSlash bool) string {
+	const hex = "0123456789ABCDEF"
+	var b strings.Builder
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' ||
+			c == '-' || c == '.' || c == '_' || c == '~' || c == '/' && keepSlash {
+			b.WriteByte(c)
+		} else {
+			b.WriteByte('%')
+			b.WriteByte(hex[c>>4])
+			b.WriteByte(hex[c&15])
+		}
+	}
+	return b.String()
+}
+
 // shellCompleter implements readline.AutoCompleter for contextual completion
 type shellCompleter struct {
 	commands []string
@@ -1334,6 +1377,7 @@ func interactive() {
 			// Report finished and stopped background jobs
 			reapJobs(true)
 			// Update prompt dynamically (in case directory changed)
+			reportCwd()
 			l.SetPrompt(getPrompt())
 		} else {
 			l.SetPrompt("> ")
@@ -2137,6 +2181,8 @@ Features:
     GOSH_COLORS='user=1;33:path=36' (keys user, root, path, error; values
     are ANSI SGR codes, empty = no color); disabled with $NO_COLOR,
     TERM=dumb or when output is not a terminal
+  - Reports the working directory to the terminal (OSC 7) before each
+    prompt, so new tabs/windows open in the same directory
   - Variables: name=value sets a variable (like set), name=value command
     sets it only for that command; the value is not split or expanded as
     a pattern

main_test.go

@@ -1133,6 +1133,31 @@ func TestBuildPrompt_ColorEscapesControlCharacters(t *testing.T) {
 	}
 }
 
+func TestOSC7Sequence(t *testing.T) {
+	tests := []struct{ host, dir, want string }{
+		{"host", "/home/flow", "\x1b]7;file://host/home/flow\a"},
+		{"host", "/tmp/a b/ä", "\x1b]7;file://host/tmp/a%20b/%C3%A4\a"},
+		{"host", "/x%y#z?", "\x1b]7;file://host/x%25y%23z%3F\a"},
+		{"", "/", "\x1b]7;file:///\a"},
+	}
+	for _, tt := range tests {
+		if got := osc7Sequence(tt.host, tt.dir); got != tt.want {
+			t.Errorf("osc7Sequence(%q, %q) = %q, want %q", tt.host, tt.dir, got, tt.want)
+		}
+	}
+}
+
+func TestOSC7Sequence_EscapesControlCharacters(t *testing.T) {
+	got := osc7Sequence("ho/st\x07", "/evil\x07\x1b]0;title\x1b\\")
+	body := strings.TrimSuffix(strings.TrimPrefix(got, "\x1b]7;"), "\a")
+	if strings.ContainsAny(body, "\x07\x1b") {
+		t.Errorf("sequence contains control characters: %q", got)
+	}
+	if !strings.HasPrefix(body, "file://ho%2Fst%07/evil%07%1B") {
+		t.Errorf("unexpected encoding: %q", got)
+	}
+}
+
 func TestUseColor_NoColor(t *testing.T) {
 	t.Setenv("NO_COLOR", "1")
 	if useColor() {

packaging/man/gosh.1

@@ -739,6 +739,13 @@ If the last command failed, its exit status is shown as
 .BI [ N ]
 before the
 .BR $ .
+.PP
+Before each prompt, gosh reports the working directory to the terminal with
+the OSC 7 escape sequence
+.RB ( "ESC ] 7 ; file://" \fIhost\fP/\fIpath\fP " BEL" ),
+so terminals like GNOME Terminal open new tabs and windows in the same
+directory. Nothing is sent if the output is not a terminal or
+.BR TERM=dumb .
 .SH ENVIRONMENT
 .TP
 .B GOSH_HISTFILE