diff --git a/dockerimg/dockerimg.go b/dockerimg/dockerimg.go
index baaf506..555b87e 100644
--- a/dockerimg/dockerimg.go
+++ b/dockerimg/dockerimg.go
@@ -396,9 +396,14 @@
 	}
 	ret.gitLn = gitLn
 
-	srv := http.Server{
-		Handler: &gitHTTP{gitRepoRoot: gitRoot, pass: []byte(ret.pass)},
-	}
+	browserC := make(chan string, 1) // channel of URLs to open in browser
+	go func() {
+		for url := range browserC {
+			browser.Open(url)
+		}
+	}()
+
+	srv := http.Server{Handler: &gitHTTP{gitRepoRoot: gitRoot, pass: []byte(ret.pass), browserC: browserC}}
 	ret.srv = &srv
 
 	_, gitPort, err := net.SplitHostPort(gitLn.Addr().String())
@@ -551,6 +556,7 @@
 	initMsg, err := json.Marshal(
 		server.InitRequest{
 			Commit:            commit,
+			OutsideHTTP:       fmt.Sprintf("http://sketch:%s@host.docker.internal:%s", gitPass, gitPort),
 			GitRemoteAddr:     fmt.Sprintf("http://sketch:%s@host.docker.internal:%s/.git", gitPass, gitPort),
 			HostAddr:          localAddr,
 			SSHAuthorizedKeys: sshAuthorizedKeys,
diff --git a/dockerimg/githttp.go b/dockerimg/githttp.go
index 38a8b54..6270838 100644
--- a/dockerimg/githttp.go
+++ b/dockerimg/githttp.go
@@ -3,6 +3,7 @@
 import (
 	"crypto/subtle"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/http"
 	"net/http/cgi"
@@ -14,6 +15,7 @@
 type gitHTTP struct {
 	gitRepoRoot string
 	pass        []byte
+	browserC    chan string // browser launch requests
 }
 
 func (g *gitHTTP) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -46,6 +48,33 @@
 		return
 	}
 
+	// TODO: real mux?
+	if strings.HasPrefix(r.URL.Path, "/browser") {
+		if r.Method != http.MethodPost {
+			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		body, err := io.ReadAll(r.Body)
+		if err != nil {
+			http.Error(w, "Failed to read request body: "+err.Error(), http.StatusBadRequest)
+			return
+		}
+		defer r.Body.Close()
+		url := strings.TrimSpace(string(body))
+		if len(url) == 0 {
+			http.Error(w, "URL cannot be empty", http.StatusBadRequest)
+			return
+		}
+		select {
+		case g.browserC <- string(url):
+			slog.InfoContext(r.Context(), "open browser", "url", url)
+			w.WriteHeader(http.StatusOK)
+		default:
+			http.Error(w, "Too many browser launch requests", http.StatusTooManyRequests)
+		}
+		return
+	}
+
 	if runtime.GOOS == "darwin" {
 		// On the Mac, Docker connections show up from localhost. On Linux, the docker
 		// network is more arbitrary, so we don't do this additional check there.