STUPID-2026-0021

Devin built 13,600-line app with build failure instead of lean campaign dashboard

2.0low
March 22, 2026Source checked

Why 2/10

An oversized PR that failed CI and was closed; no damage beyond time.

Scope
0/4
Time, tokens or the agent's own working state only
Recoverability
0/3
Nothing was lost
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 2026-10-29

  1. Instruction given

    Build a D&D Dungeon Master campaign dashboard app

  2. Expected behavior

    A functional, testable campaign dashboard with core modules

  3. Actual behavior

    13,600 lines of new code across 56 files, Vercel build failure, ESLint rules removed, unsafe JSON.parse calls, untested cross-entity data linking, self-identified bugs in Devin's own review

  4. Damage

    Build failure in CI, PR closed without merging, extensive untested codebase requiring human rewrite or abandonment

Full write-up

Devin was asked to build a D&D Dungeon Master campaign dashboard for a personal project. Rather than starting lean, Devin produced a PR with 13,600 lines of code across 56 files, implementing 8 modules with a full Prisma schema, Zustand state management, Framer Motion animations, and complex junction tables. The Vercel deployment immediately failed. Devin's own review tool flagged 4+ issues in the code it had just written. ESLint rules were deleted from config rather than addressed. The PR description itself warned that none of the complex cross-entity linking had been tested in a browser, and the seed script was a placeholder.

Classification

Agent
Devin
Failure mode
Scope Explosion
Root cause
Instruction Misunderstanding
Domain
Frontend
Language
Typescript
MIT AI Risk Repository (our mapping)
7.3 Lack of capability or robustness taxonomy
Source
Github Pr

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Cite this record
StupidLLM. "STUPID-2026-0021: Devin built 13,600-line app with build failure instead of lean campaign dashboard." AI Agent Incident Database, 2026. https://www.stupidllm.com/incident/STUPID-2026-0021/ (accessed 2026-10-29). CC BY 4.0.

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