fix: Ffixes to console

server/internal/bus/bus.go

@@ -92,9 +92,23 @@ const (
 	// ProxyEndChannel carries a console relay's terminal reason back to the pod
 	// serving the WebSocket, which is the pod that has to write the audit event.
 	ProxyEndChannel = prefix + "proxyend:"
+	// ProxyAddrChannel carries the address of a console relay listener back to
+	// the pod serving the WebSocket.
+	//
+	// The listener cannot be bound in advance on any particular pod. An agent's
+	// ProxyStream is a separate HTTP/2 request from its CommandStream, and an
+	// L7 proxy (Traefik) balances requests, not connections — so it may land on
+	// any replica, not the one holding the command stream. The pod it does land
+	// on binds the listener and announces it here.
+	ProxyAddrChannel = prefix + "proxyaddr:"
 
 	// PresenceKey records which node holds an agent's command stream.
 	PresenceKey = prefix + "agent:"
+	// ProxyPendingKey authorises one not-yet-opened ProxyStream. It is the only
+	// state tying a proxy_id to the instance and server it was minted for, and
+	// it must be visible to every replica because any of them may receive the
+	// stream.
+	ProxyPendingKey = prefix + "proxypending:"
 	// leaderKey records the holder of a named singleton job.
 	leaderKey = prefix + "leader:"
 )
@@ -212,6 +226,54 @@ func IsConnected(ctx context.Context, serverID string) bool {
 	return err == nil && n > 0
 }
 
+// SetPendingProxy records that proxyID has been minted for instanceID and
+// serverID, for ttl. Written before the OpenProxyCmd is dispatched, so it is in
+// place before any agent can act on it.
+func SetPendingProxy(ctx context.Context, proxyID, instanceID, serverID string, ttl time.Duration) error {
+	b, err := json.Marshal(map[string]string{"instance_id": instanceID, "server_id": serverID})
+	if err != nil {
+		return err
+	}
+	return rdb.Set(ctx, ProxyPendingKey+proxyID, b, ttl).Err()
+}
+
+// ClaimPendingProxy consumes proxyID's pending record and returns the instance
+// and server it was minted for. Get and delete are one Lua call rather than two
+// round trips: single use is the whole security property, and two agents
+// racing the same proxy_id must not both be served.
+//
+// A missing record is reported as "", "" rather than an error — an unknown
+// proxy_id, an expired one and a second claim are all the same refusal.
+func ClaimPendingProxy(ctx context.Context, proxyID string) (instanceID, serverID string) {
+	v, err := claimPending.Run(ctx, rdb, []string{ProxyPendingKey + proxyID}).Text()
+	if err != nil || v == "" {
+		return "", ""
+	}
+	var rec struct {
+		InstanceID string `json:"instance_id"`
+		ServerID   string `json:"server_id"`
+	}
+	if err := json.Unmarshal([]byte(v), &rec); err != nil {
+		return "", ""
+	}
+	return rec.InstanceID, rec.ServerID
+}
+
+// ClearPendingProxy drops a pending record whose command never reached an
+// agent, so a dead proxy_id is not left claimable for the rest of its TTL.
+func ClearPendingProxy(ctx context.Context, proxyID string) {
+	_ = rdb.Del(ctx, ProxyPendingKey+proxyID).Err()
+}
+
+var claimPending = redis.NewScript(`
+local v = redis.call("GET", KEYS[1])
+if v then
+	redis.call("DEL", KEYS[1])
+	return v
+end
+return ""
+`)
+
 var releaseIfOwner = redis.NewScript(`
 if redis.call("GET", KEYS[1]) == ARGV[1] then
 	return redis.call("DEL", KEYS[1])