argus-agents 0.5.1

Production readiness platform for AI agent pipelines — detects silent failures, captures full state, enables step-level replay.

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Production readiness platform for AI agent pipelines.

Your LangGraph pipeline runs. No exception. But three nodes later something crashes with a KeyError. The node that crashed didn't cause it — some node upstream returned a dict with a missing field, and nothing caught it.

ARGUS sits between your nodes and catches silent failures, semantic degradation, and contract violations before they reach production.

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Install

pip install argus-agents

Setup — pick whichever fits your code

Option A — before compile:

from argus import ArgusWatcher

watcher = ArgusWatcher()
watcher.watch(graph)       # before graph.compile()
app = graph.compile()
app.invoke(initial_state)
watcher.finalize()

Option B — after compile (new in v0.5.0):

from argus import ArgusWatcher

watcher = ArgusWatcher()
app = graph.compile(checkpointer=memory)
app = watcher.watch_compiled(app)   # works on already-compiled graphs
app.invoke(initial_state)
watcher.finalize()

Both work. No changes to your node functions.

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What it catches

Silent failures — a node returns {} or drops a required field. No exception, pipeline keeps running. ARGUS compares each node's output against the next node's type annotations and flags it before the crash happens downstream.

Semantic failures — structure is fine but the value is wrong. Pass a validator:

watcher = ArgusWatcher(validators={
    "classify": lambda o: (o.get("label") in ["yes", "no"], "unexpected label"),
    "*":        lambda o: ("error" not in o, "error key present"),
})

"*" runs on every node.

Crashes — full traceback captured per node, with a one-line root cause:

└─  KeyError: 'score'
└─  at pipeline.py:47  →  result = state["score"] * weight
└─  Field 'score' was absent from the incoming state

Strict mode — additional patterns: nested error keys, rate limit responses, empty required lists, list[int] vs list[str] type mismatches. Use in staging/CI:

watcher = ArgusWatcher(strict=True)

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Output

argus  run-abc12345  ·  2024-04-05 12:30  ·  1243 ms
status  ●  silent_failure

   1  fetch       43 ms    ✓  pass
   2  validate    12 ms    ⚠  silent failure
      └─  Field "score" is missing
      └─  process received bad state
   3  process    891 ms    ✗  crashed
      └─  KeyError: 'score'
      └─  Field 'score' was absent from the incoming state

root cause   validate

Parallel nodes shown as a grouped panel. Cyclic graphs show each iteration separately. Human interrupt chains stitched into one trace on resume.

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Rerun

A 10-node pipeline fails at node 7. You fix the bug. Instead of re-running nodes 1–6 and burning API credits:

argus replay <run-id> node_7

ARGUS restores the exact state at node 7 from disk and runs from there. Upstream outputs stay frozen. Only node 7 onward re-executes with your fixed code.

From the web UI — hover any step, click ↺ Rerun From Here. After rerun, the diff view opens automatically.

argus diff <rerun-id>    # compare rerun vs original

What about external API calls?

By default, reruns call external APIs live (OpenAI, search tools, databases). Results may differ from the original run.

For fully deterministic reruns, record HTTP calls during the original run:

watcher = ArgusWatcher(record_http=True)

Every API response is saved to disk. During rerun, the recorded responses are served back — same data, zero extra cost, fully reproducible.

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Semantic Judge (LLM-powered)

Deterministic checks catch ~80% of production failures (missing fields, empty results, type mismatches, placeholder outputs). For the remaining 20% — subtle quality issues like wrong tone, unhelpful responses, or outdated information — enable the semantic judge:

watcher = ArgusWatcher(semantic_judge=True)

The LLM judge runs after deterministic checks on every node. It evaluates output quality, generates causal hypotheses, and suggests debugging steps.

# With a specific model
watcher = ArgusWatcher(semantic_judge=True, judge_model="gpt-4o")

# Combined with HTTP recording for deterministic + intelligent monitoring
watcher = ArgusWatcher(semantic_judge=True, record_http=True)

Requires OPENAI_API_KEY in your environment. Uses GPT-4o by default.

When to use: complex multi-agent pipelines, customer-facing outputs, LLM-generated content where quality matters.

When to skip: simple pipelines, CI/CD speed runs, zero-cost monitoring.

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Diagnose setup issues

argus doctor

✓  python           Python 3.9.6
✓  langgraph        langgraph 0.6.11
✓  storage          312 runs stored, all healthy
✓  replay           all 7 node functions importable for rerun
✓  optional deps    openai (key set), dotenv

5 seconds to know if something is wrong — Python version, LangGraph compatibility, storage health, rerun readiness.

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CLI

argus list                          # all runs
argus show last                     # most recent run
argus show run <id>                 # by full id or 8-char prefix
argus replay <id> <node>            # re-run from a node
argus replay <id> <node> --only     # re-run just that one node
argus inspect <id> --step <node>    # raw input/output for a node
argus diff <id>                     # rerun vs original
argus diff <id-a> <id-b>            # any two runs
argus ui                            # open web dashboard
argus doctor                        # check your setup
argus login                         # sync runs to cloud

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Web UI

argus ui

Opens at http://localhost:7842. Serves runs from .argus/runs/ in your current directory — no account needed.

Run detail, rerun tree, side-by-side diff, LLM cost per node, AI root cause investigation.

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Node statuses

✓	pass
~	pass with warnings (empty optional fields)
⚠	silent failure (missing required fields)
⊗	semantic fail (validator returned False)
⏸	interrupted (human-in-the-loop pause)
✗	crashed

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Without LangGraph

from argus import ArgusSession

session = ArgusSession()
session.set_edges({"fetch": ["classify"], "classify": ["process"]})

fetch    = session.wrap("fetch",    fetch_fn)
classify = session.wrap("classify", classify_fn)
process  = session.wrap("process",  process_fn)

state = fetch(initial_state)
state = classify(state)
state = process(state)
session.finalize()

Works with Prefect, Temporal, or plain Python functions.

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Requires Python 3.9+. LangGraph 0.2+ only needed for ArgusWatcher.

v0.5.1 — changelog