feat: add --orchestration startup flag to gate spawn tool

Orchestration (subagent spawning) is now opt-in rather than always-on.
The spawn tool is only registered when orchestration is explicitly enabled,
preventing the LLM from having a tool it has no guidance to use.

Changes:
- config: SubagentsConfig.Enabled bool (opt-in per agent via JSON config)
- config: AgentDefaults.Orchestration bool (env PICOCLAW_AGENTS_DEFAULTS_ORCHESTRATION)
- agent/instance: apply defaults.Orchestration to agent.Subagents at construction
- agent/loop: gate spawn tool registration on agent.Subagents.Enabled
- cmd/agent: --orchestration flag sets cfg.Agents.Defaults.Orchestration = true

Usage: picoclaw agent --orchestration

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

cmd/picoclaw/cmd_agent.go

@@ -24,6 +24,7 @@ func agentCmd() {
 	message := ""
 	sessionKey := "cli:default"
 	modelOverride := ""
+	orchestrationEnabled := false
 
 	args := os.Args[2:]
 	for i := 0; i < len(args); i++ {
@@ -46,6 +47,8 @@ func agentCmd() {
 				modelOverride = args[i+1]
 				i++
 			}
+		case "--orchestration":
+			orchestrationEnabled = true
 		}
 	}
 
@@ -59,6 +62,10 @@ func agentCmd() {
 		cfg.Agents.Defaults.Model = modelOverride
 	}
 
+	if orchestrationEnabled {
+		cfg.Agents.Defaults.Orchestration = true
+	}
+
 	provider, modelID, err := providers.CreateProvider(cfg)
 	if err != nil {
 		fmt.Printf("Error creating provider: %v\n", err)

pkg/agent/instance.go

@@ -91,6 +91,15 @@ func NewAgentInstance(
 		skillsFilter = agentCfg.Skills
 	}
 
+	// Apply defaults.Orchestration: if the flag is set, ensure orchestration is enabled.
+	if defaults.Orchestration {
+		if subagents == nil {
+			subagents = &config.SubagentsConfig{Enabled: true}
+		} else {
+			subagents.Enabled = true
+		}
+	}
+
 	maxIter := defaults.MaxToolIterations
 	if maxIter == 0 {
 		maxIter = 20

pkg/agent/loop.go

@@ -216,15 +216,17 @@ func registerSharedTools(
 		agent.Tools.Register(tools.NewFindSkillsTool(registryMgr, searchCache))
 		agent.Tools.Register(tools.NewInstallSkillTool(registryMgr, agent.Workspace))
 
-		// Spawn tool with allowlist checker
-		subagentManager := tools.NewSubagentManager(provider, agent.Model, agent.Workspace, msgBus)
-		subagentManager.SetLLMOptions(agent.MaxTokens, agent.Temperature)
-		spawnTool := tools.NewSpawnTool(subagentManager)
-		currentAgentID := agentID
-		spawnTool.SetAllowlistChecker(func(targetAgentID string) bool {
-			return registry.CanSpawnSubagent(currentAgentID, targetAgentID)
-		})
-		agent.Tools.Register(spawnTool)
+		// Spawn tool — only registered when orchestration is explicitly enabled.
+		if agent.Subagents != nil && agent.Subagents.Enabled {
+			subagentManager := tools.NewSubagentManager(provider, agent.Model, agent.Workspace, msgBus)
+			subagentManager.SetLLMOptions(agent.MaxTokens, agent.Temperature)
+			spawnTool := tools.NewSpawnTool(subagentManager)
+			currentAgentID := agentID
+			spawnTool.SetAllowlistChecker(func(targetAgentID string) bool {
+				return registry.CanSpawnSubagent(currentAgentID, targetAgentID)
+			})
+			agent.Tools.Register(spawnTool)
+		}
 
 		// Update context builder with the complete tools registry
 		agent.ContextBuilder.SetToolsRegistry(agent.Tools)

pkg/config/config.go

@@ -141,6 +141,7 @@ type AgentConfig struct {
 }
 
 type SubagentsConfig struct {
+	Enabled     bool              `json:"enabled,omitempty"`
 	AllowAgents []string          `json:"allow_agents,omitempty"`
 	Model       *AgentModelConfig `json:"model,omitempty"`
 }
@@ -182,6 +183,7 @@ type AgentDefaults struct {
 	Temperature          *float64 `json:"temperature,omitempty"           env:"PICOCLAW_AGENTS_DEFAULTS_TEMPERATURE"`
 	MaxToolIterations    int      `json:"max_tool_iterations"             env:"PICOCLAW_AGENTS_DEFAULTS_MAX_TOOL_ITERATIONS"`
 	TaskReminderInterval int      `json:"task_reminder_interval"          env:"PICOCLAW_AGENTS_DEFAULTS_TASK_REMINDER_INTERVAL"`
+	Orchestration        bool     `json:"orchestration,omitempty"         env:"PICOCLAW_AGENTS_DEFAULTS_ORCHESTRATION"`
 }
 
 type ChannelsConfig struct {