tools: dispatch_with_agent uses agent's tool list

When agent is provided, looks up the tool in agent.tools first.
Falls back to global registry for agent-less dispatch (MCP server,
subconscious agents).

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/tools/mod.rs

@@ -166,11 +166,25 @@ pub async fn dispatch(
 }
 
 /// Dispatch a tool call with optional agent context.
+/// If agent is provided, uses the agent's tool list.
 pub async fn dispatch_with_agent(
     name: &str,
     args: &serde_json::Value,
     agent: Option<std::sync::Arc<tokio::sync::Mutex<super::Agent>>>,
 ) -> String {
+    // Look up in agent's tools if available, otherwise global
+    if let Some(ref agent) = agent {
+        let agent_guard = agent.lock().await;
+        if let Some(tool) = agent_guard.tools.iter().find(|t| t.name == name) {
+            let handler = tool.handler;
+            drop(agent_guard);
+            return match handler(Some(agent.clone()), args.clone()).await {
+                Ok(s) => s,
+                Err(e) => format!("Error: {}", e),
+            };
+        }
+    }
+    // Fallback to global registry
     for tool in tools() {
         if tool.name == name {
             return match (tool.handler)(agent, args.clone()).await {