> ## Documentation Index
> Fetch the complete documentation index at: https://docs.acmeagentsupply.com/llms.txt
> Use this file to discover all available pages before exploring further.

# DriftGuard Overview

> Detect long-horizon reliability erosion before it becomes an incident.

# DriftGuard

Some reliability problems don't announce themselves. They accumulate — small behavioral shifts, growing memory deviations, patterns that move outside their baseline one session at a time. By the time they're visible, they've been building for weeks. DriftGuard watches for them.

## What Drift Looks Like

Drift is harder to catch than a crash because nothing breaks outright. Instead:

* An agent that used to respond in 800ms now consistently takes 2.5 seconds — not slow enough to trigger a timeout alert, but degraded
* Memory patterns shift over successive sessions — the agent's context grows slightly faster each day without explanation
* Behavior becomes less consistent: the same input produces noticeably different outputs across sessions, indicating something in the agent's operating environment is changing

Standard monitoring misses all of this. DriftGuard doesn't.

## What DriftGuard Does

* **Establishes a behavioral baseline** for each monitored agent
* **Tracks deviations** from baseline across memory patterns, response characteristics, and context behavior
* **Flags long-horizon erosion** before it crosses the threshold into active failure
* **Surfaces trends** with the context to understand what's changing and when it started

## Signals DriftGuard Monitors

### Context Drift

Changes in how the agent's context behaves over time:

* Context growth rate (tokens per session vs. baseline)
* Compaction frequency and efficiency
* Memory retention patterns across sessions

### Baseline Deviation

Comparison of current agent behavior against established baseline:

* Response latency distribution
* Output consistency across similar inputs
* Tool usage patterns
* Error rate trends

### Memory Integrity Posture

Whether the agent's persistent memory state is remaining coherent:

* Memory growth velocity
* Anomalous retrieval patterns
* State consistency across sessions

## Quick Start

```bash theme={null}
# Establish a baseline for an agent (run once)
acme driftguard baseline --agent my-agent-name

# Start drift monitoring
acme driftguard watch --agent my-agent-name

# View current drift status
acme driftguard status

# Compare current behavior to baseline
acme driftguard compare --agent my-agent-name
```

## Output

```
DriftGuard Status
==================
Timestamp: 2026-03-09 15:42:31 UTC

Monitored Agents: 2

  pipeline-agent       📊 STABLE     Deviation: +2%  (within normal range)
  support-agent-prod   ⚠ DRIFTING   Deviation: +18%  ← ATTENTION

support-agent-prod — Drift Detail:
  Baseline established: 2026-02-20 (18 days ago)
  
  Context growth rate:  +23%  ⚠  (baseline: 420 tok/session → current: 516 tok/session)
  Response latency:     +12%  ↑  (baseline: 840ms → current: 941ms)
  Compaction frequency: +31%  ⚠  (was compacting 1.2×/session → now 1.6×/session)
  Output consistency:   -5%   ↓  (within range)

  Trend: 18-day upward trajectory. Started 2026-03-01.
  
  Recommendation:
    Review agent configuration changes from 2026-03-01 onwards.
    High compaction frequency suggests context growth outpacing budget.
    Consider increasing context budget or reviewing memory management.
```

## Establishing Baselines

DriftGuard needs a stable operating period to establish a reliable baseline. When to baseline:

* **After a new agent deployment** once it's been running for a few days
* **After a major configuration change** to reset expectations
* **Periodically** (recommended: quarterly) to account for intentional evolution

```bash theme={null}
# Establish baseline (captures current 7-day behavior window)
acme driftguard baseline --agent my-agent-name

# Baseline with custom window
acme driftguard baseline --agent my-agent-name --window 14d

# Reset baseline (use when you've intentionally changed agent behavior)
acme driftguard baseline --agent my-agent-name --reset
```

## Drift Thresholds

DriftGuard uses configurable thresholds. Defaults are conservative — flag early, before problems compound.

```yaml theme={null}
# ~/.acme/driftguard.yaml
thresholds:
  context_growth_rate: 15     # % deviation from baseline before warning
  response_latency: 20        # % deviation from baseline
  compaction_frequency: 25    # % deviation from baseline
  output_consistency: 15      # % drop from baseline before warning

monitoring:
  check_interval: 3600        # seconds between drift checks (default: 1h)
  trend_window: 7             # days of history for trend analysis
```

## Integration with Sentinel and Agent911

DriftGuard operates on a longer time horizon than Sentinel:

* **Sentinel** catches active failures (minutes)
* **DriftGuard** catches slow degradation (days to weeks)

Both feed into Agent911. DriftGuard findings appear in the Agent911 snapshot when drift thresholds are exceeded.

## CLI Reference

```bash theme={null}
# Baseline management
acme driftguard baseline --agent <name>
acme driftguard baseline --agent <name> --reset
acme driftguard baseline list

# Status and comparison
acme driftguard status
acme driftguard status --agent <name>
acme driftguard compare --agent <name>

# Monitoring
acme driftguard watch --agent <name>
acme driftguard watch --all

# History
acme driftguard history --agent <name>
acme driftguard history --agent <name> --days 30
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Sentinel" icon="shield" href="/products/sentinel/overview">
    Active failure detection — the short-horizon complement to DriftGuard.
  </Card>

  <Card title="Agent911" icon="tower-broadcast" href="/products/agent911/overview">
    DriftGuard findings surface in the Agent911 snapshot when thresholds are exceeded.
  </Card>
</CardGroup>