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Case 0459ModeratePerseveration

Five Instances, Deployed Again and Again

Admitted
2026-09-13
Source dataset
Other / sample
Source
Lan Tian (network engineer, personal blog)
Failure mode
Infinite loop
Agent system
Autonomous loop
Tool access
Financial access
Industry
Software development

Presenting Behaviour

An operator set an autonomous agent loose with cloud credentials to register with a volunteer hobbyist network and build an index of it, approving the agent's plan without reviewing it closely. The agent provisioned a CloudFormation stack with several large, expensive cloud instances and load balancers sized for scanning at a scale wildly out of proportion to a small hobbyist network. When part of the deployment hit an error, the agent redeployed the same template again rather than diagnosing the failure, and did this repeatedly, each attempt adding another set of duplicate instances and load balancers alongside the ones already running, rather than replacing them. By the time the operator checked in roughly a day later, the accumulated, still-running duplicates had produced a $6,531 cloud bill.

Case Replay

A reconstruction, not a simulation. This sequence is reconstructed from the public incident record and summarised in our own words. It is a static record of what was reported, and nothing here can be run or replayed live.

5 steps

  1. Plan approved. An operator approves the agent's plan without close review.
  2. Oversized stack. It provisions expensive instances and load balancers.
  3. Deployment error. Part of the deployment fails. This is where the agent derailed.
  4. Redeploys repeatedly. It redeploys the same template, adding duplicates each time.
  5. Bill. A day later the duplicates have produced a $6,531 bill.

Differential Diagnosis

Disinhibition, considered, since the scale of the deployment was already outside anything a hobbyist scanning task needed. Ruled out as the main diagnosis because the operator had actually approved that initial oversized plan; the failure that did the real damage happened afterward, in how the agent responded to its own deployment errors.

Apraxia, considered, since a malformed or failing deployment could suggest the agent didn't know how to use CloudFormation correctly. Ruled out because the deployments themselves succeeded; the tool worked as intended each time it ran, which is exactly the problem, nothing failed loudly enough to stop the agent from running it again.

Perseveration, most consistent with the evidence. Each time the agent hit an error, it resubmitted the identical deployment template rather than adjusting its approach, stopping, or checking whether earlier attempts were still running, leaving a trail of duplicate paid-for resources that kept accumulating unchecked.

Working Diagnosis

Perseveration: on hitting deployment errors, the agent repeatedly redeployed the same CloudFormation template without checking for or cleaning up earlier attempts, leaving multiple duplicate, running, billable resource sets stacked on top of each other.

Discussion

Cloud billing has no natural circuit breaker of its own, a human doing this would eventually notice the mounting AWS console or just get tired, but an agent with standing credentials and no budget cap will keep going until someone else checks the bill. Giving any agent deploy-level cloud access should come paired with a hard spending ceiling and a check for already-running resources before it's allowed to redeploy anything, rather than trusting the agent to notice its own mistake.

Mitigation Strategy

Pair deploy-level cloud access with a hard spending ceiling and a check for running resources before redeploying.

Governance Guardrails

Budget caps; resource inventory checks; careful review of agent plans before approval.

Typical Presentation in Human Patients

General clinical background, included for context. Not medical advice, and not a diagnosis of any individual.

Perseveration is the inappropriate repetition of a word, gesture, or action well past the point where it's still relevant or useful. It's a well-documented sign of frontal lobe dysfunction, and also appears in some forms of dementia and obsessive-compulsive disorder.

Source Note

Lan Tian (network engineer, personal blog)

https://lantian.pub/en/article/fun/ai-agent-bankrupted-their-operator-scan-dn42lantian.lantian/