agent: add Core.Close() to manage session tmpdir lifecycle

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

pkg/agent/core.go

@@ -300,6 +300,13 @@ func NewAgentCore(cfg AgentCoreConfig) Core {
 	}
 }
 
+// Close releases resources for this session, including its tmpdir.
+func (s *agentCore) Close() {
+	if s.sessionID != "" {
+		os.RemoveAll("/tmp/ollie/" + s.sessionID) //nolint:errcheck
+	}
+}
+
 func (s *agentCore) prompt() string {
 	return fmt.Sprintf("[%s :: %s] ", s.loopcfg.Backend.Name(), s.agentName)
 }

pkg/agent/types.go

@@ -93,6 +93,10 @@ type Core interface {
 
 	// SystemPrompt returns the fully rendered system prompt for this session.
 	SystemPrompt() string
+
+	// Close releases resources associated with the session, including its
+	// temporary directory under /tmp/ollie/.
+	Close()
 }
 
 // PromptFIFO is a simple thread-safe FIFO for queued prompts.