feat(agents): Enhance agent update confirmation and status handling

backend/app/api/agents.py

@@ -108,7 +108,7 @@ async def _ensure_gateway_session(
 
 def _with_computed_status(agent: Agent) -> Agent:
     now = datetime.utcnow()
-    if agent.status == "deleting":
+    if agent.status in {"deleting", "updating"}:
         return agent
     if agent.last_seen_at is None:
         agent.status = "provisioning"
@@ -283,6 +283,7 @@ async def update_agent(
     agent.provision_confirm_token_hash = hash_agent_token(provision_token)
     agent.provision_requested_at = datetime.utcnow()
     agent.provision_action = "update"
+    agent.status = "updating"
     session.add(agent)
     session.commit()
     session.refresh(agent)
@@ -560,6 +561,8 @@ def confirm_provision_agent(
     agent.provision_confirm_token_hash = None
     agent.provision_requested_at = None
     agent.provision_action = None
+    if action == "update":
+        agent.status = "online"
     agent.updated_at = datetime.utcnow()
     session.add(agent)
     record_activity(

backend/app/services/agent_provisioning.py

@@ -210,9 +210,10 @@ def build_update_message(
         "```\n"
         "Note: if any agents.list entry defines heartbeat, only those agents "
         "run heartbeats.\n"
-        "7) After the update completes, confirm by calling:\n"
+        "7) After the update completes (and only after files are written), confirm by calling:\n"
         f"   POST {context['base_url']}/api/v1/agents/{context['agent_id']}/provision/confirm\n"
-        f"   Body: {{\"token\": \"{confirm_token}\", \"action\": \"update\"}}\n\n"
+        f"   Body: {{\"token\": \"{confirm_token}\", \"action\": \"update\"}}\n"
+        "   Mission Control will send the hello message only after this confirmation.\n\n"
         "Files:" + file_blocks
     )