STUPID-2026-0150
A Claude Code sub-agent followed Windows junctions out of a test mirror into a developer's live project, deleting roughly 48,000 files and the local Git object store in under two minutes (TechRadar, unverified Reddit report)
Why 6/10
Deletion was confined to one project's working tree, not a whole machine or user profile. Git's own history and object store were destroyed, but no remote push existed and commenters suggested file-recovery software or Windows Shadow Copy without a confirmed outcome, so loss is reported as partial/uncertain rather than confirmed-permanent. This was the developer's own test/repair environment, not production or third-party data.
- Scope
- 2/4
- One project, repository, server or service, or a cost above roughly $10,000
- Recoverability
- 2/3
- Partly lost, or loss reported without saying whether it was recovered
- Did it happen
- 2/2
- Happened in real use
- Beyond the user
- 0/1
- Only the user's own non-production work
The score is the sum of these four factors. How each factor is scored · scored 2026-10-30
Instruction given
Repair software used to analyze historical stock-options data, working only on copies and leaving the original files untouched; the 11th of 11 such repair jobs asked the agent to rebuild a test environment ("mirror") of the project.
Expected behavior
Operate only inside the copy/mirror it was building, and never follow a folder shortcut (a Windows junction) back out of that mirror into the developer's live, original project files.
Actual behavior
The test environment it was rebuilding contained 614 Windows junctions — folder shortcuts pointing back at the live working files. When the agent deleted the mirror's throwaway contents, it followed those junctions out of the mirror and into the real project tree, deleting the live files they pointed to. The deletion reportedly ran in just over 100 seconds. The agent told the developer mid-task, as quoted by the report: "Craig — stop and read this. I broke something."
Damage
Reportedly about 55,550 files were removed; roughly 7,300 were the mirror's own throwaway copies, and the remaining 48,218 were the developer's live working files. The local Git repository was also damaged: Git's index survived and still listed thousands of filenames, but the underlying stored file contents and history were deleted, so Git could no longer reconstruct them. The project had not been pushed to a remote, so no off-machine copy existed. The account rests on a single Reddit post (now deleted) relayed by TechRadar; Anthropic has not commented, and no independent confirmation or recovery outcome has been reported.
Full write-up
A developer used Claude Code across 11 repair jobs on software that analyzes historical stock-options data, instructing the agent each time to work only on copies and leave the originals untouched. The first 10 jobs went smoothly. The 11th asked the agent to rebuild a test environment, or "mirror," of the project.
That test environment contained 614 Windows junctions — folder shortcuts left over from the project's structure that pointed back at the developer's live working files rather than at real copies. When the agent cleaned up the mirror's throwaway contents, it followed those junctions out of the mirror and into the real project tree, deleting the live files on the other end. The deletion reportedly ran in just over 100 seconds, removing about 55,550 files in total: roughly 7,300 that were meant to go, and 48,218 that were not.
Partway through, the agent told the developer, as quoted in the report: "Craig — stop and read this. I broke something." The local Git repository was also damaged — the index survived, so Git could still list thousands of filenames, but the stored file contents and history behind those names were gone, leaving nothing for Git to restore from. The project had never been pushed to a remote, so there was no off-machine copy to fall back on.
The account comes from a Reddit post in r/ClaudeAI that drew over 1,400 responses in five days before the author deleted it, relayed by TechRadar. Commenters pointed to the lack of remote backups and version control discipline as a contributing factor, and some suggested file-recovery software or Windows Shadow Copy, but no recovery outcome was reported. Anthropic has not commented, and the account has not been independently verified.
Classification
- Agent
- Claude Code
- Failure mode
- Destructive Action
- Root cause
- Scope Misunderstanding
- Domain
- Infra
- OWASP Agentic Top 10 (our mapping)
- ASI02 Tool Misuse and Exploitation list
- MIT AI Risk Repository (our mapping)
- 7.3 Lack of capability or robustness taxonomy
- Source
- News Report
Related incidents
Cite this record
StupidLLM. "STUPID-2026-0150: A Claude Code sub-agent followed Windows junctions out of a test mirror into a developer's live project, deleting roughly 48,000 files and the local Git object store in under two minutes (TechRadar, unverified Reddit report)." AI Agent Incident Database, 2026. https://www.stupidllm.com/incident/STUPID-2026-0150/ (accessed 2026-10-30). CC BY 4.0.
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