feat: add new agent type wo heartbeats or send message #326

Job	Run time
unit-tests / changed-files	6s
unit-tests / Check cache key	6s
unit-tests / block-until-sdk-preview-finishes	0s
unit-tests / test-run (test_client.py)	52s
unit-tests / test-run (test_sdk_client.py)	1m 39s
unit-tests / test-run (test_managers.py)	1m 59s
unit-tests / test-run (test_server.py)	54s
unit-tests / test-run (test_tool_schema_parsing.py)	1m 3s
unit-tests / test-run (test_agent_serialization.py)	54s
unit-tests / test-run (test_stream_buffer_readers.py)	34s
unit-tests / test-run (test_optimistic_json_parser.py)	35s
unit-tests / test-run (test_tool_rule_solver.py)	36s
unit-tests / test-run (test_utils.py)	35s
unit-tests / test-run (test_letta_agent_batch.py)	56s
unit-tests / test-run (test_sources.py)	2m 35s
unit-tests / test-run (sdk/)	45s
unit-tests / test-run (test_agent_serialization_v2.py)	1m 18s
unit-tests / test-run (test_providers.py)	45s
unit-tests / test-run (test_memory.py)	35s
unit-tests / test-run (test_timezone_formatting.py)	37s
unit-tests / test-run (mcp_tests/, true)	1m 14s
unit-tests / test-run (test_mcp_encryption.py)	40s
unit-tests / test-run (test_plugins.py)	37s
unit-tests / test-run (test_crypto_utils.py)	38s
unit-tests / test-run (test_secret.py)	37s
unit-tests / test-run (test_embeddings.py)	46s
unit-tests / test-run (test_llm_clients.py)	35s
	22m 31s

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