Add a pause that holds an agent after its current step

internal/agents/compact.go

@@ -3,6 +3,7 @@ package agents
 import (
 	"context"
 	"errors"
+	"fmt"
 	"log/slog"
 	"strings"
 
@@ -33,7 +34,13 @@ func (m *Manager) Compact(ctx context.Context, sessionID, model string) (api.Age
 	if err != nil {
 		return api.AgentSession{}, err
 	}
+	unlock := m.lockDelivery(sessionID)
+	if m.isPaused(sessionID) {
+		unlock()
+		return api.AgentSession{}, fmt.Errorf("%w: session %s is paused; resume it first", ErrConflict, sessionID)
+	}
 	err = m.startRunning(ctx, sess, "byre")
+	unlock()
 	if err != nil {
 		return api.AgentSession{}, err
 	}
@@ -72,6 +79,7 @@ func isContinuation(actor, text string) bool {
 
 func (m *Manager) continueFromHandoff(sessionID, handoff string) {
 	ctx := context.Background()
+	m.waitResumed(sessionID)
 	err := m.handoff(ctx, sessionID, handoff)
 	if err == nil {
 		return