{"slug": "i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one", "title": "I replaced 200 lines of ad-hoc state management in my Hermes agent with one object.", "summary": "A developer replaced 200 lines of ad-hoc state management in a Hermes research agent with a single `StateBag` object. The object wraps a dictionary with features for snapshotting, diffing, incrementing, and saving state, enabling rollback on failure and turn-by-turn replay. The solution uses only Python standard library modules and is available as the `agent-state-bag` package.", "body_md": "*This is a submission for the Hermes Agent Challenge.*\n\nMy Hermes research agent was tracking state across 20+ variables. Turn counter. Running cost. Message history. Sub-tasks done. Sub-tasks pending. Errors per tool. Each was a standalone variable at the top of the loop, updated individually, saved separately, and restored manually after a crash.\n\nBy turn 47, the state management was 200 lines of ad-hoc code spread across the loop. I replaced it with one object.\n\n``` python\nfrom agent_state_bag import StateBag\n\nstate = StateBag({\n    \"turn\": 0,\n    \"cost_usd\": 0.0,\n    \"messages\": [],\n    \"sub_tasks_done\": [],\n    \"errors\": 0,\n})\n\nfor turn in range(1, 50):\n    state[\"turn\"] = turn\n    state.increment(\"cost_usd\", 0.05)\n    state.increment(\"errors\") if tool_failed else None\n\n    response = call_llm(state[\"messages\"])\n    state[\"messages\"].append({\"role\": \"assistant\", \"content\": response.text})\n```\n\n`StateBag`\n\nis a dict wrapper with extra features. It passes through all the dict methods you expect, plus the things a long-running agent actually needs.\n\n```\nstate.push_turn()   # saves current state to history\n\n# If the turn fails badly, restore to before this turn\nstate.reset_to(state.last_snapshot())\n```\n\nAt the start of each turn, push a snapshot. If something goes catastrophically wrong mid-turn, you can roll back to the clean state before that turn started.\n\n```\nsnap = state.snapshot()\n\n# ... agent does stuff ...\n\nchanges = state.diff(snap)\n# {\"cost_usd\": (0.15, 0.20), \"messages\": (old_list, new_list), \"sub_tasks_done\": ([], [\"task1\"])}\n```\n\nI log the diff to my trace file at the end of each turn. When reviewing a run, I can see exactly what each turn changed — without comparing full state snapshots manually.\n\n```\nstate.increment(\"turn\")               # += 1\nstate.increment(\"cost_usd\", 0.05)     # += 0.05\nstate.decrement(\"retries_left\")       # -= 1\n```\n\nReturns the new value. Initializes to 0 if the key is missing.\n\n```\nstate.save(\"state.json\")\nstate = StateBag.load(\"state.json\")\n```\n\nPlain JSON. Grep-able, inspectable, resumable. I save state after every successful turn. On crash, `StateBag.load`\n\nrestores exactly where I was.\n\n```\nstate.push_turn()    # checkpoint this turn\n# ...10 more turns...\nstate.history        # list of all saved snapshots\nstate.turn_count     # 11\nstate.last_snapshot() # most recent snapshot\n```\n\nThe history grows across the run. After the run, I can replay it to see how state evolved turn by turn.\n\n```\n# Worker agent's output state\nstate.merge(worker_output)   # other wins on conflict; deep-copied\n```\n\nIn my multi-agent setup, workers return their results as dicts. The supervisor merges them into its own state.\n\nStandard library only: `json`\n\n, `copy`\n\n, `dataclasses`\n\n, `typing`\n\n. No third-party packages.\n\n```\npip install agent-state-bag\n```\n\n", "url": "https://wpnews.pro/news/i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one", "canonical_source": "https://dev.to/mukundakatta/i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one-object-24fa", "published_at": "2026-05-25 21:21:08+00:00", "updated_at": "2026-05-25 21:34:11.504703+00:00", "lang": "en", "topics": ["ai-agents", "ai-tools", "ai-infrastructure"], "entities": ["Hermes", "StateBag"], "alternates": {"html": "https://wpnews.pro/news/i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one", "markdown": "https://wpnews.pro/news/i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one.md", "text": "https://wpnews.pro/news/i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one.txt", "jsonld": "https://wpnews.pro/news/i-replaced-200-lines-of-ad-hoc-state-management-in-my-hermes-agent-with-one.jsonld"}}