argus-agents 0.8.2

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

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Catch silent failures in AI agent pipelines before production.

Your LangGraph pipeline runs fine — no exception. But three nodes later, something crashes with a KeyError. The real cause? A node upstream silently dropped a field. ARGUS catches this.

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Install

pip install argus-agents

Quick Start

from argus import ArgusWatcher

watcher = ArgusWatcher(graph)       # attach to your StateGraph
app = graph.compile()
result = app.invoke(initial_state)
watcher.finalize()                  # persist the run to .argus/runs/

ARGUS monitors every node, detects failures, and saves the run. No changes to your node functions.

Always call watcher.finalize() after app.invoke(). Required for cyclic graphs, safe for all. Without it the run stays in memory and won't appear in argus list or the dashboard.

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What It Catches

Problem	Example
Silent failures	Node returns {} or drops a required field — no exception, pipeline keeps running broken
Semantic failures	Output structure is fine but values are wrong (placeholders, refusals, degraded text)
Loop stalls	Agent retries 5 times producing identical output — stuck loop burning tokens
Unnecessary retries	Loop produces correct answer on attempt 2, but validator forces 3 more iterations
Crash root cause	Traces KeyError at node 5 back to the upstream node that actually dropped the field
Contract violations	Output types don't match the next node's expected input schema

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Detection Layers

Runs in order, each more expensive — only fires when needed:

1. Heuristics — 150+ failure signatures (placeholders, empty results, error keys, semantic degradation). Zero cost.
2. Anomaly detector — statistical checks for output size anomalies, timing outliers. Deterministic.
3. Correlator — traces failure propagation across nodes. Points at the origin, not the crash site.
4. LLM investigator — root cause explanations and debugging suggestions. Only on ambiguous failures.
5. Loop analyzer — LLM analysis for looped nodes: summarizes iterations, detects stalls, flags wasted retries.

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Loop-Aware Inspection

Pipelines with loops (LLM -> compiler -> if fail, retry) get special treatment:

• Earlier iterations that self-corrected are marked retried (not counted as failures)
• Only the final iteration determines pass/fail
• LLM analyzes every loop: what went wrong, what changed between attempts, whether retries were necessary
• Dashboard shows iteration badges, collapse/expand, and natural-language loop summaries

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Replay

Fix a bug, re-run from the failing node. Skip upstream nodes entirely:

argus replay <run-id> node_7          # re-run from node_7 onward
argus replay <run-id> node_7 --only   # just that one node
argus diff <rerun-id>                 # compare vs original

External API calls (OpenAI, etc.) are recorded by default — replays are free and deterministic.

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Semantic Judge

For subtle quality issues that pattern matching can't catch:

watcher = ArgusWatcher(graph, semantic_judge=True)  # enabled by default

LLM evaluates output quality on every passing node. Catches wrong tone, unhelpful responses, outdated info. Requires OPENAI_API_KEY.

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Custom Validators

watcher = ArgusWatcher(graph, 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
})

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CLI

argus list                           # all recorded runs
argus show last                      # most recent run
argus show <id>                      # inspect a specific run
argus inspect <id> --step <node>     # dump raw input/output for a node
argus replay <id> <node>             # re-run from a node
argus diff <id-a> <id-b>             # compare two runs
argus ui                             # web dashboard
argus doctor                         # check setup health
argus login                          # sign in for cloud sync
argus logout                         # clear stored credentials
argus whoami                         # show current login status
argus update                         # check for newer release

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Web Dashboard

argus ui    # opens at localhost:7842

Shows all runs, node-level detail, AI analysis, replay diffs, loop iteration badges, and comparison views. No account needed for local use.

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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 any framework — Prefect, Temporal, plain Python.

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Requirements

• Python 3.9+
• LangGraph 0.2+ (only for ArgusWatcher)
• OPENAI_API_KEY in env for semantic features (optional — all heuristic detection works without it)

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v0.8.2 — changelog