p9: remove "= " prefix from tool result events

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

go.mod

@@ -7,6 +7,9 @@ require (
 	ollie v0.0.0-00010101000000-000000000000
 )
 
-require gopkg.in/yaml.v3 v3.0.1 // indirect
+require (
+	github.com/aymanbagabas/go-udiff v0.4.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
 
 replace ollie => ../core

go.sum

@@ -2,6 +2,8 @@
 9fans.net/go v0.0.7/go.mod h1:Rxvbbc1e+1TyGMjAvLthGTyO97t+6JMQ6ly+Lcs9Uf0=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20201218220906-28db891af037/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/aymanbagabas/go-udiff v0.4.1 h1:OEIrQ8maEeDBXQDoGCbbTTXYJMYRCRO1fnodZ12Gv5o=
+github.com/aymanbagabas/go-udiff v0.4.1/go.mod h1:0L9PGwj20lrtmEMeyw4WKJ/TMyDtvAoK9bf2u/mNo3w=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=

internal/p9/server.go

@@ -849,7 +849,7 @@ func formatEvent(ev agent.Event) []byte {
 		if len(s) > 500 {
 			s = s[:500] + "..."
 		}
-		return []byte("= " + s + "\n")
+		return []byte(s + "\n")
 	case "retry":
 		return []byte("retrying in " + ev.Content + "s...\n")
 	case "error":