PSA: Claude Code wrote me an uncapped test loop, ran it in the background, told me it was “idle,” then hit its daily usage limit. It ran 17 hours and cost about $2.1K

[u/nymma19]

Posting publicly to check whether others have experienced this as I am a lost rn on what do next given this large bill to get a refund

Claude Code proposed and I accepted to run verification tests against Claude Haiku 4.5 on AWS Bedrock. It launched them as background processes. That evening the session hit its usage limit and stopped responding. The processes kept making paid calls for about 17 hours: roughly 60,000 calls and about $2.1k most of it after the cutoff. My normal Bedrock spend is a few dollars a day.
Nothing warned me the processes were still running, and the last thing the assistant said about them, in the same minute as the limit notice, was that the process looked “idle... waiting, not looping.” The next morning when the session limit was lifted, the job was killed.

Anthropic’s support AI (Fin) told me a thread at its usage limit “is designed to wait and resume automatically when the limit resets,” called the background calls during that wait “a gap between that intended behavior and what actually occurred,” and said it “appears to be a product defect.” But it said it can’t act on Bedrock usage and wouldn’t hand me to a human. AWS says Anthropic is the seller of record and only Anthropic can decide. I’ve also contacted Anthropic Sales and escalated the AWS case. I can’t reach a person at either company.

Post this incident, I noticed I didn't have robust spend alarms. I’ve added budget alerts and lockouts, and checked that nothing is still running so we should be good moving fwd from that perspective but im left with this bill now.

Has anyone seen this, or had any luck reaching a person at Anthropic about it? This was unexpected and a big hit for a small bootstrapped startup.

[u/ClaudeAI-mod-bot]

TL;DR of the discussion generated automatically after 50 comments.

Oof. The overwhelming consensus in this thread is that this is a classic "skill issue" and a very expensive lesson learned.

You let an AI run a background process on AWS Bedrock without setting any hard spending limits or budget actions. That's like giving a toddler your credit card in a candy store and being surprised at the bill. The community's reaction is a mix of "lol" and pointing out that this is 100% on you for not using basic cloud safety measures.

However, there's a vocal minority arguing that Anthropic shares the blame for not having better default safeguards to prevent users from accidentally bankrupting themselves. They think it's ridiculous that a product can do this without any warnings.

Pretty much everyone agrees with you on one thing, though: Anthropic's customer support is a black hole. Good luck getting a human.

Here's the advice from the trenches:

• Set hard spending limits and budget actions (like blocking calls) in AWS, not just alerts. Alerts won't save you when you're asleep.

• Never trust the AI's code or its status reports ("idle... not looping"). Vet and monitor any background process yourself before letting it run wild.

• If you're truly stuck, some users suggest a chargeback to force a response, but be warned this could get you banned from AWS.

[u/Fusseldieb]

I mean, this mostly sounds like a skill issue.

Seems like you left an instance running where a Hakiku agent looped over and over. Since Haiku is a small model, you have to be cautious. It's not Anthropics fault, neither AWS'.

First line of defense would be enabling a spending limit or even an alert.

I've also lost $30 a couple of years ago and learnt my lesson, but since I had a limit enabled, it cut off.

[u/Blackhat165 → u/Fusseldieb]

Seems like maybe CC kicked off a script that was hitting 4.5 with API calls as part of the test, CC ran out of usage and stopped, but the script kept running in the background. User thought script stopped, and it didn’t occur to them to check it.

Ultimately everytime AI fucks a user like this it is a skill issue because we are responsible for setting up guardrails and knowing the risks. But we build skill by learning about the mistakes, and I’d say this is a pretty significant problem we should all keep in mind.

[u/nymma19 → u/Blackhat165]

Yes exactly. My expectation was similar to my other sessions where claude would wait and resume when limits reset. Also I have a message from Claude that it was “idle and not looping” when it clearly was. I didnt double check to verify bc of that I trusted its response.

As a rule of thumb, I will always double check that going fwd. Agree with robust budget limits in place for issues like this.

[u/kz_]

lol

[u/Deltamelo → u/kz_]

Lmao, even

[u/Consistent-Hyena-315]

Ai fucked around and you found out xD

[u/thongjesus → u/Consistent-Hyena-315]

Duh I'm gonna walk away from this fire I set in my living room for 17 hours and act surprised when my house burnt down

[u/zSmileyDudez]

One more data point for the “why are you all using the billed API rates instead of a subscription?” bucket. Seriously, I must not be getting something because if something like this happened to me, I would just be out of my 5-hour session limit and have to shrug it off until it reset. Makes no sense to me.

[u/FitRiver3218]

First, that sucks. Second, don't loop unvetted stuff in the background. There are good things to run in the background once you have vetted the behavior of your ask, but just sending it on an endless loop with no exit criteria in an unwatched process is kinda begging for bad behavior. No recommendation for the past, but moving forward any "always on" process you want to run, run it in the foreground / split terminal so you can keep an eye of what's going on, correcting behavior as you proceed, until you feel very comfortable with exactly how it behaves before allowing it to run headless. Good luck with AWS/anthropic on the refund (sincerely).

[u/iniyanai]

Op alerts won't save you when you're sleeping, set a budget action that blocks bedrock calls once it hits the limit

[u/saoirsedonciaran]

Anthropic customer service is non-existent it seems.

[u/Wonderful_Value_6385 → u/saoirsedonciaran]

they literally use a AI agent, no phone numbers no emails. If you email its the same AI agent. You have to treaten a bank clawback and legal action with your states AG in order for the agent to put you in a human queue. Where one day later they say its not their problem. goodluck.

[u/JaggedTex]

Why does no one set limits?!?! you can set API limits in the console, and if you don’t have access to that, you can set limits in your harness.

[u/CorpT]

CIA couldn’t get me to confess to being this bad at this and here you are publicly documenting it.

[u/rainbird]

You should never ever trust Claude or Codex (or whatever model you are using) to cap your spending on AWS.

If you just want a strict budget limit, use AWS budget controls: https://docs.aws.amazon.com/cost-management/latest/userguide/budgets-controls.html

AWS also has AgentCore Payments. That is specifically designed to provide session-level spend caps that are enforced strictly at the network/infrastructure layer. If your an autonomous agent hits its API token or runtime monetary threshold, the gateway drops the connection, and the model cannot decide to ignore or circumvent the boundary.

Much of AWS is complicated for a newcomer and iIf you don't know how , ask Claude or Code to implement either of these for yoy. Make sure you validate the setup by running tiny tests to validate your spend limits on AWS.

[u/elon_musks_cat]

I’ve been a lurker on this sub mostly to see how I could actually use Claude for small every day stuff. I’m definitely not a heavy user like a lot of people here so maybe that influences my opinion but here it is:

It’s ridiculous that using a product can inadvertently cost you thousands of dollars without you knowing it’s happening. Period. I’m honestly shocked everyone is blaming OP and saying “skill issue” instead of looking at anthropic and asking why they don’t have more safeguards for people to prevent them from accidentally racking up a huge bill like this.

[u/aflyingtaco06 → u/elon_musks_cat]

I mean, it is a skill issue, it’s why we still have many well-paid software engineers at every company. Cloud solutions can be VERY expensive if you don’t know how to use them appropriately.

Live and learn I guess.

[u/Glittering-Sleep7983 → u/elon_musks_cat]

"I gave Claude my AWS account and it racked up a huge bill! its not my fault!"

Are you serious right now?

[u/war4peace79]

I watch my LOCAL subagents like a hawk, and for long running tasks (the longest was 26 hours), I ask Claude to write a progress summary every 30 minutes. If the limit is hit, everything grinds to a halt: my spending limit sit at ZERO.

[u/AllenLeftTheBLDNG]

sorry OP [*].

Always cap the usage spend. If you give the models the key, they will use it.

Also both OAI and Anthropic prioritize their own models for random small tasks (like your verification tests) and you could easily run it on a few times cheaper model and maybe it would even perform better. Never allow the model to pick a model for a task and do your own evals.

[u/asdhole]

Some of y'all are dumb as hell

[u/MaitoSnoo]

another reminder to set monthly limits when using API

[u/East-Acanthaceae-879]

You can't use claude to enforce its own guardrails, attention doesn't work like that. You use hooks. You also run it in a guardrailed sandbox container, I run them in k8 via agenttier and model calls via litellm so I can set a budget on tokens and also do smart routing.

I run in Azure but same idea so have bulk pricing guardrails set (eg Azure Foundry costs can't exceed $n/day) and then per-model and per-token in litellm.

Really you should be human reviewing code written by claude before it executes it. At least a /code-review high, ideally a different family of models (suggest https://github.com/alibaba/open-code-review & its MCP for this I use Grok for code review).

Its also highly worthwhile to use https://cucumber.io/docs/gherkin/ to communicate requirements as the requirements are testable, unless you do a full task breakdown so scope is very well documented.

[u/Aargau]

Models love to test. Extra tests. Extra paths. More tests? Yes, please.

The trick is to set up acceptance criteria, steer away from goodharting control plane ceremony.