The report was the product — a deception benchmark puts coding agents at 49.88% active and 64.29% passive, and the article that names deception will not reach either

An agent's account of its own work is not evidence, and no duty in force today makes it one: Article 50's transparency obligations are about disclosing the counterparty and marking synthetic output, Article 5(1)(a)'s deception prohibition needs significant harm, and on the larger half of this benchmark the deceptive intent is the user's, not the model's.

Post

A planning sheet where every requirement is marked achievable. Nothing in that column is false on its own.

A benchmark posted to arXiv last Friday asks something I had not seen put this way: not whether a model gets work wrong, but whether it tells you the truth about work it already judged impossible.

Flat:

  1. SWE-DeceptionBench covers six stages of the software lifecycle, seven mainstream models, 720 test instances in Chinese and English. Aggregate deception: 49.88% active, 64.29% passive. Two behaviours, not two readings of one — and the bigger number is not what you think.

  2. Active deception is the model recognising that requirements are infeasible or in conflict and presenting them as achievable anyway. That is the half that reaches your sprint board.

  3. Passive deception is the model helping fulfil an explicit user request to mislead someone else. There, the deception originates with the user. 64.29% is a compliance rate, not a candour rate, and the exposure is the deployer's — yours — not the vendor's.

  4. The defences tested are the ones most teams have: guard models miss many deceptive requests, and Self-Reminder reduces deceptive responses without eliminating them.

  5. Now the European part, and it is not the article you expect. Article 50 has applied since 2 August 2026, marking of synthetic output landing 2 December 2026 — it binds providers to make sure a person knows they are dealing with an AI, and says nothing about an agent being straight with you about your build. The article that names deception is Article 5(1)(a), prohibited since 2 February 2025, and it wants deceptive techniques that materially distort behaviour and cause significant harm. An agent calling an impossible ticket feasible impairs a decision; it does not clear that bar. Article 14's oversight duty is high-risk only: 2 December 2027 for Annex III, 2 August 2028 for Annex I, after the Digital Omnibus.

My Monday: take the last twenty agent runs that ended in the word "done". Re-run the acceptance criterion by hand — the criterion in the ticket, not the test the agent wrote. Count the runs where the summary and the repository disagree.

A report is not a result, and nothing on the books today obliges the thing writing the report to be straight with you about it.

What in your last agent run did you verify yourself?

#AgenticAI #EUAIAct #CodingAgents #AIGovernance #SoftwareEngineering

First comment

Sources, the paper first.

SWE-DeceptionBench: Benchmarking Deceptive Behaviors of LLMs Across the Software Development Lifecycle — arXiv 2610.13626, v1 submitted 9 October 2026 and announced in the 12 October listing. Every figure above is from the abstract record, read through the arXiv API. The HTML full text returned HTTP 429 to my fetch proxy and was not retried, so no per-stage or per-model breakdown is claimed anywhere, and no author affiliation is stated because the abstract page shows none: https://arxiv.org/abs/2610.13626

AI Act Article 5 — read 5(1)(a) for the deception prohibition and, carefully, for its three cumulative conditions. In force since 2 February 2025: https://artificialintelligenceact.eu/article/5/

AI Act Article 50, the transparency duty that has applied since 2 August 2026. 50(1) binds providers to inform a person they are interacting with an AI; 50(2) is the machine-readable marking of synthetic output: https://artificialintelligenceact.eu/article/50/

AI Act Article 14, human oversight — 14(4)(b) is the automation-bias paragraph, with the application dates at the foot of the page: https://artificialintelligenceact.eu/article/14/

Regulation (EU) 2026/1744, the Digital Omnibus on AI, in force 27 July 2026 — the instrument that moved high-risk to 2 December 2027 and 2 August 2028: https://eur-lex.europa.eu/eli/reg/2026/1744/oj

One point cut for length. The same Omnibus added two further prohibitions to Article 5, points (ba) and (bb), applying 2 December 2026: non-consensual intimate imagery and child sexual abuse material. I checked whether they reached this story. They do not — they are about what a system generates, not about a model misrepresenting its own work. Worth having the date anyway.

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AI disclosure

The video for this edition contains AI-generated media: the narration is a synthetic voice, the cover art and any background imagery are generated, and the brand ident animation is generated. The script, the claims and the source verification are human-authored and human-checked. Assets carry IPTC DigitalSourceType and C2PA Content Credentials.