session: move uname to Agent, remove peers from core

- uname is the agent's principal/UID, not a session property
- peers removed entirely from core: the concept needs redesign for
  multi-agent. The 9P layer retains its own inter-session routing
  at the Manager level.

Core Session now holds only: id, bus, env, plan, prevPrompt.
Agent holds all execution + identity state.

session/agent.go

@@ -31,6 +31,7 @@ type Agent struct {
 	state    string // "idle", "thinking", "calling: <tool>"
 	reply    string // last assistant response
 	cwd      string // working directory for tool execution
+	uname    string // agent principal (numeric UID for 9P identity)
 	fifo     Fifo   // prompt queue
 	toolCallCount atomic.Int64
 	pendingInject atomic.Pointer[string]

session/commands.go

@@ -175,7 +175,7 @@ func (a *Session) handleCommand(ctx context.Context, input string) bool {
 				return
 			}
 			d := a.r.newDispatcher()
-			env := []string{"OLLIE_SESSION_ID=" + a.id, "OLLIE_UNAME=" + a.uname}
+			env := []string{"OLLIE_SESSION_ID=" + a.id, "OLLIE_UNAME=" + a.r.uname}
 			env = append(env, a.r.promptEnvExtra...)
 			rt := BuildRuntime(cfg, d, a.r.cwd, env, a.r.baseLayers...)
 			if rt.CfgBackend != "" {

session/session.go

@@ -310,13 +310,11 @@ type Config struct {
 type Session struct {
 	// Session-level state
 	id       string
-	uname    string
 	bus      *pubsub.Bus
 	envMu    sync.RWMutex
 	env      map[string]string
 	plan     []byte
 	prevPrompt string
-	peers    map[string]bool
 
 	// Agent
 	r            *Agent
@@ -367,8 +365,8 @@ func (a *Session) pushSessionEnv() {
 	if srv, ok := a.r.runtime.Dispatcher.GetServer("execute"); ok {
 		if es, ok := srv.(tools.EnvSetter); ok {
 			es.SetEnv("OLLIE_SESSION_ID", a.id)
-			if a.uname != "" {
-				es.SetEnv("OLLIE_UNAME", a.uname)
+			if a.r.uname != "" {
+				es.SetEnv("OLLIE_UNAME", a.r.uname)
 			}
 		}
 	}
@@ -459,7 +457,7 @@ func New(cfg Config) *Session {
 
 	a := &Session{
 		id:    cfg.SessionID,
-		uname: cfg.Uname,
+		
 		bus:   pubsub.NewBus(),
 		env:   make(map[string]string),
 		r: &Agent{