fix: read the listen port from a bare host:port self endpoint (#36)

Codefly hands a service its own endpoint as a bare host:port (a rendered cell
writes "localhost:8080"); url.Parse reads that as scheme "localhost" with no
port, so every rendered solution refused to boot with 'unresolved listen port
""'. listenPort accepts both the bare form and a URL.

Co-authored-by: Antoine Toussaint <312536060+antoinetoussaint-byte@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: antoinetoussaint-byte

listen_port_test.go

@@ -0,0 +1,21 @@
+package solution
+
+import "testing"
+
+// TestListenPortReadsEitherAddressForm pins the two shapes Codefly hands a
+// service for its own endpoint: a rendered cell writes the bare host:port, a
+// local run a URL. The bare form is the one url.Parse misreads as a scheme.
+func TestListenPortReadsEitherAddressForm(t *testing.T) {
+	for address, want := range map[string]string{
+		"localhost:8080":         "8080",
+		"http://localhost:8080":  "8080",
+		"http://127.0.0.1:41234": "41234",
+		"[::1]:9000":             "9000",
+		"localhost":              "",
+		"":                       "",
+	} {
+		if got := listenPort(address); got != want {
+			t.Errorf("listenPort(%q) = %q, want %q", address, got, want)
+		}
+	}
+}

solution.go

@@ -256,6 +256,24 @@ func env(key, fallback string) string {
 // could not resolve it. Using the SDK keeps addresses and ports out of the
 // runtime: they come from Codefly's runtime-injected endpoint map (or, in a
 // local run, its deterministic native workspace map) — never a hardcoded port.
+// listenPort is the port of this service's own endpoint address. Codefly hands a
+// service its own endpoint as a bare "host:port" (a rendered cell writes
+// "localhost:8080"), and other endpoints as URLs; url.Parse reads the bare form
+// as scheme "localhost" with no port, which left every rendered solution
+// refusing to boot with an empty listen port. Both forms resolve here.
+func listenPort(self string) string {
+	if strings.Contains(self, "://") {
+		if u, err := url.Parse(self); err == nil {
+			return u.Port()
+		}
+		return ""
+	}
+	if _, port, err := net.SplitHostPort(self); err == nil {
+		return port
+	}
+	return ""
+}
+
 func address(ctx context.Context, module, service, endpoint, api string) string {
 	q := codefly.For(ctx).Endpoint(endpoint)
 	if module != "" {
@@ -386,9 +404,7 @@ func loadConfig(ctx context.Context, id string) config {
 	port := env("PORT", "")
 	if port == "" {
 		if self := address(ctx, "", "", "http", "http"); self != "" {
-			if u, err := url.Parse(self); err == nil {
-				port = u.Port()
-			}
+			port = listenPort(self)
 		}
 	}
 	public := env("PUBLIC_URL", "")