diff --git a/agent/agent.go b/agent/agent.go
index 73753c5..0a60de9 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -29,7 +29,7 @@ type Agent struct {
 	agentsDir      string
 	baseLayers     []string // system prompt layers for /agent reloads
 	promptEnvExtra []string // PRIME_* vars for prompt resolution
-	newDispatcher  func() tools.Dispatcher
+	newToolServer  func() tools.Server
 	newBackend     func(string) (backend.Backend, error)
 	currentAction  atomic.Pointer[actionHandle]
 	warnedContext  bool
@@ -258,10 +258,10 @@ func (ag *Agent) ToolCallCount() int64 {
 
 // SetSessionEnv injects session env vars into the execute server.
 func (ag *Agent) SetSessionEnv(sessionID string) {
-	if ag.runtime.Dispatcher == nil {
+	if ag.runtime.ExecServer == nil {
 		return
 	}
-	if srv, ok := ag.runtime.Dispatcher.GetServer("execute"); ok {
+	if srv := ag.runtime.ExecServer; srv != nil {
 		if es, ok := srv.(tools.EnvSetter); ok {
 			es.SetEnv("OLLIE_SESSION_ID", sessionID)
 			if ag.id != "" {
@@ -273,10 +273,10 @@ func (ag *Agent) SetSessionEnv(sessionID string) {
 
 // SetEnv stores an environment variable on the execute server.
 func (ag *Agent) SetEnv(key, value string) {
-	if ag.runtime.Dispatcher == nil {
+	if ag.runtime.ExecServer == nil {
 		return
 	}
-	if srv, ok := ag.runtime.Dispatcher.GetServer("execute"); ok {
+	if srv := ag.runtime.ExecServer; srv != nil {
 		if es, ok := srv.(tools.EnvSetter); ok {
 			es.SetEnv(key, value)
 		}
@@ -285,10 +285,10 @@ func (ag *Agent) SetEnv(key, value string) {
 
 // Close releases agent resources (dispatcher, execute server).
 func (ag *Agent) Close() {
-	if ag.runtime.Dispatcher == nil {
+	if ag.runtime.ExecServer == nil {
 		return
 	}
-	if srv, ok := ag.runtime.Dispatcher.GetServer("execute"); ok {
+	if srv := ag.runtime.ExecServer; srv != nil {
 		if c, ok := srv.(interface{ Close() }); ok {
 			c.Close()
 		}
@@ -302,8 +302,8 @@ func (ag *Agent) SetCWD(dir string) {
 	if oldCwd != "" && dir != "" && oldCwd != dir {
 		ag.runtime.Preamble = strings.ReplaceAll(ag.runtime.Preamble, oldCwd, dir)
 	}
-	if ag.runtime != nil && ag.runtime.Dispatcher != nil {
-		if srv, ok := ag.runtime.Dispatcher.GetServer("execute"); ok {
+	if ag.runtime.ExecServer != nil {
+		if srv := ag.runtime.ExecServer; srv != nil {
 			if ws, ok := srv.(tools.CWDSetter); ok {
 				ws.SetCWD(dir)
 			}
@@ -472,13 +472,9 @@ func (ag *Agent) React(responseID, emoji string) error {
 	return nil
 }
 
-// execServer returns the execute server interface, or nil if unavailable.
-func (ag *Agent) execServer() interface{} {
-	if ag.runtime.Dispatcher == nil {
-		return nil
-	}
-	srv, _ := ag.runtime.Dispatcher.GetServer("execute")
-	return srv
+// execServer returns the execute server, or nil if unavailable.
+func (ag *Agent) execServer() tools.Server {
+	return ag.runtime.ExecServer
 }
 
 // Queue pushes a prompt onto the agent's FIFO.
diff --git a/agent/build_runtime.go b/agent/build_runtime.go
index 35024b9..bfb53d9 100644
--- a/agent/build_runtime.go
+++ b/agent/build_runtime.go
@@ -17,7 +17,7 @@ import (
 // env provides additional environment variables injected into prompt resolution
 // subprocesses (e.g. OLLIE_SESSION_ID=xxx).
 // The caller is responsible for registering all servers on d before calling this.
-func BuildRuntime(cfg *AgentConfig, d tools.Dispatcher, cwd string, env []string, baseLayers ...string) *Runtime {
+func BuildRuntime(cfg *AgentConfig, srv tools.Server, cwd string, env []string, baseLayers ...string) *Runtime {
 	var messages []string
 
 	var allToolInfos []tools.ToolInfo
@@ -25,7 +25,7 @@ func BuildRuntime(cfg *AgentConfig, d tools.Dispatcher, cwd string, env []string
 
 	if cfg == nil || cfg.ToolsEnabled() {
 		var listErr error
-		allToolInfos, listErr = d.ListTools()
+		allToolInfos, listErr = srv.ListTools()
 		if listErr != nil {
 			messages = append(messages, fmt.Sprintf("list tools: %v", listErr))
 		}
@@ -69,30 +69,14 @@ func BuildRuntime(cfg *AgentConfig, d tools.Dispatcher, cwd string, env []string
 		}
 		maxSteps = cfg.MaxSteps
 		if len(cfg.AllowTools) > 0 {
-			if srv, ok := d.GetServer("execute"); ok {
-				if rs, ok := srv.(tools.ToolRestrictionSetter); ok {
-					rs.SetAllowTools(cfg.AllowTools)
-				}
+			if rs, ok := srv.(tools.ToolRestrictionSetter); ok {
+				rs.SetAllowTools(cfg.AllowTools)
 			}
 		}
 	}
 
 	exec := func(ctx context.Context, name string, args json.RawMessage) (string, []backend.ContentBlock, error) {
-		infos, listErr := d.ListTools()
-		if listErr != nil {
-			return "", nil, listErr
-		}
-		server := ""
-		for _, t := range infos {
-			if t.Name == name {
-				server = t.Server
-				break
-			}
-		}
-		if server == "" {
-			return "", nil, fmt.Errorf("unknown tool: %s", name)
-		}
-		raw, err := d.Dispatch(ctx, server, name, args)
+		raw, err := srv.CallTool(ctx, name, args)
 		if err != nil {
 			return "", nil, err
 		}
@@ -104,24 +88,20 @@ func BuildRuntime(cfg *AgentConfig, d tools.Dispatcher, cwd string, env []string
 	}
 
 	var classify toolClassifier
-	if srv, ok := d.GetServer("execute"); ok {
-		if pc, ok := srv.(tools.ParallelClassifier); ok {
-			classify = pc.IsParallelRead
-		}
+	if pc, ok := srv.(tools.ParallelClassifier); ok {
+		classify = pc.IsParallelRead
 	}
 
 	var tierFn func(string, json.RawMessage) ResultTier
-	if srv, ok := d.GetServer("execute"); ok {
-		if tc, ok := srv.(tools.TierClassifier); ok {
-			tierFn = func(name string, args json.RawMessage) ResultTier {
-				switch tc.ResultTierArgs(name, args) {
-				case "cold":
-					return TierCold
-				case "warm":
-					return TierWarm
-				default:
-					return TierHot
-				}
+	if tc, ok := srv.(tools.TierClassifier); ok {
+		tierFn = func(name string, args json.RawMessage) ResultTier {
+			switch tc.ResultTierArgs(name, args) {
+			case "cold":
+				return TierCold
+			case "warm":
+				return TierWarm
+			default:
+				return TierHot
 			}
 		}
 	}
@@ -160,7 +140,7 @@ func BuildRuntime(cfg *AgentConfig, d tools.Dispatcher, cwd string, env []string
 	}
 
 	return &Runtime{
-		Dispatcher:      d,
+		ExecServer:   srv,
 		Tools:           allTools,
 		Exec:            exec,
 		ClassifyTool:    classify,
diff --git a/agent/commands.go b/agent/commands.go
index 5922caf..e0af3db 100644
--- a/agent/commands.go
+++ b/agent/commands.go
@@ -180,7 +180,7 @@ func (ag *Agent) cmdAgent(_ context.Context, args []string) {
 		ag.emit(infoEvent(fmt.Sprintf("error: agent %q: %v", name, err)))
 		return
 	}
-	disp := ag.newDispatcher()
+	disp := ag.newToolServer()
 	env := []string{"OLLIE_SESSION_ID=" + ag.sessionID, "OLLIE_UNAME=" + ag.id}
 	env = append(env, ag.promptEnvExtra...)
 	rt := BuildRuntime(cfg, disp, ag.cwd, env, ag.baseLayers...)
diff --git a/agent/new.go b/agent/new.go
index 9533447..a94b434 100644
--- a/agent/new.go
+++ b/agent/new.go
@@ -19,7 +19,7 @@ type AgentCfg struct {
 	CWD            string // working directory for tool execution
 	BaseLayers     []string
 	PromptEnvExtra []string
-	NewDispatcher  func() tools.Dispatcher
+	NewToolServer  func() tools.Server
 	NewBackend     func(string) (backend.Backend, error)
 	Bus            *pubsub.Bus
 	Log            *olog.Logger
@@ -42,7 +42,7 @@ func NewAgent(cfg AgentCfg) *Agent {
 		cwd:             cfg.CWD,
 		baseLayers:      cfg.BaseLayers,
 		promptEnvExtra:  cfg.PromptEnvExtra,
-		newDispatcher:   cfg.NewDispatcher,
+		newToolServer:   cfg.NewToolServer,
 		newBackend:      cfg.NewBackend,
 		bus:             cfg.Bus,
 		log:             cfg.Log,
diff --git a/agent/runtime.go b/agent/runtime.go
index 5074a05..ba3f0ee 100644
--- a/agent/runtime.go
+++ b/agent/runtime.go
@@ -13,7 +13,7 @@ import (
 // agents replaces it atomically.
 type Runtime struct {
 	Backend      backend.Backend
-	Dispatcher   tools.Dispatcher
+	ExecServer   tools.Server // the execute server (tool runtime, env, cwd)
 	Hooks        Hooks
 	Preamble     string // compiled system prompt
 	Tools        []backend.Tool
diff --git a/session/session.go b/session/session.go
index 0066411..72f2ceb 100644
--- a/session/session.go
+++ b/session/session.go
@@ -32,7 +32,7 @@ type Config struct {
 	CWD            string
 	History        *agent.History
 	Runtime        *agent.Runtime
-	NewDispatcher  func() tools.Dispatcher
+	NewToolServer  func() tools.Server
 	NewBackend     func(string) (backend.Backend, error)
 	Log            *olog.Logger
 	MaxSteps       int
@@ -150,7 +150,7 @@ func New(cfg Config) *Session {
 		CWD:            paths.ExpandHome(cfg.CWD),
 		BaseLayers:     cfg.BaseLayers,
 		PromptEnvExtra: cfg.PromptEnvExtra,
-		NewDispatcher:  cfg.NewDispatcher,
+		NewToolServer:  cfg.NewToolServer,
 		NewBackend:     cfg.NewBackend,
 		Bus:            bus,
 		Log:            log,