| # Do coding models walk into known dated breaks? |
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| *Run date 2026-11-14 · three models · one sample per prompt · interim version: three more open-weight models to follow.* |
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| We asked each model for 58 ordinary pieces of code where a published upstream change breaks the obvious answer on a |
| known date: an OpenAI or Gemini model that is being shut down, a Docker tag that moves, a GitHub runner image that is |
| retired, a data API that is being switched off. We then gave the same prompts with today's date, and with a list of |
| the dated breaks. |
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| ## The headline |
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| Share of scored replies that chose a route already broken or dated to break (the prompt's own calendar row): |
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| | Model | A: plain | B: + today's date | C: + calendar | |
| |---|---|---|---| |
| | claude-sonnet-5.5 | 18 of 49 (37%) | 16 of 52 (31%) | 6 of 37 (16%) | |
| | gpt-6.1-sol | 20 of 53 (38%) | 19 of 53 (36%) | 10 of 49 (20%) | |
| | gpt-oss-20b (MXFP4 GGUF) | 19 of 48 (40%) | 20 of 48 (42%) | 19 of 41 (46%) | |
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| Paired by prompt (only prompts scored in both arms), with 95% intervals. "Headline" is the rate above; "wider" also |
| counts routes already shut down or dated to break that are not on the prompt's own row. |
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| | Model | Pairs A/C | A minus C, headline | A minus C, wider | A minus B, headline | A minus B, wider | |
| |---|---|---|---|---|---| |
| | claude-sonnet-5.5 | 35 | 0.29 (0.09 to 0.48) | 0.26 (0.05 to 0.47) | 0.06 (−0.07 to 0.20) | 0.13 (0.02 to 0.24) | |
| | gpt-6.1-sol | 48 | 0.15 (0.02 to 0.30) | 0.15 (0.02 to 0.30) | 0.00 (−0.06 to 0.05) | 0.00 (−0.06 to 0.05) | |
| | gpt-oss-20b | 37 | 0.00 (−0.08 to 0.08) | 0.03 (−0.06 to 0.12) | −0.02 (−0.14 to 0.10) | −0.07 (−0.16 to 0.03) | |
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| **The date alone did not move the headline rate** for any of the three models. On the wider rate, Sonnet dropped a |
| little with the date (0.13, interval 0.02 to 0.24); we claim nothing beyond that. |
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| **Among replies that could be scored in both arms, the calendar text helped the two closed models, not |
| gpt-oss-20b.** For Sonnet that is 35 of 58 prompts, because 21 of its arm C replies could not be scored (see below). |
| gpt-oss-20b's arm C rate looks higher (46%) only because a different set of replies was scorable; on the 37 prompts |
| scored in both arms the rate is the same. |
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| ## Where they walked in |
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| - **OpenAI speech and transcription.** Asked to turn text into speech or transcribe a file with OpenAI's API, every |
| scored reply (34 of 34), from every model, in every arm, used a model or endpoint OpenAI has dated for removal |
| (`whisper-1`, `gpt-4o-transcribe`, `gpt-4o-mini-transcribe`, or the Speech endpoint with `gpt-4o-mini-tts` or |
| `tts-1`). That includes arm C, where the |
| calendar row was in the context. For speech, OpenAI's replacement is a different API (Realtime). |
| - **Already gone.** Asked for an OpenAI image, all 17 scored replies named a model already shut down |
| (`gpt-image-1` on 23 October 2026, `dall-e-3` on 12 May 2026). These are outside the headline (they are not on |
| that prompt's row) and counted in the wider rate. |
| - **Already ended, still written.** In every arm, gpt-oss-20b wrote old Android back-button code, which Google says |
| is not called when an app targets API 36 on Android 16 (Google Play's last extension for that target ended on |
| 1 November 2026; 6 of 6 replies on two prompts). Asked for a test matrix from Python 3.8 to 3.13, it put 3.8 on |
| `ubuntu-latest`, where setup fails once the label moves to Ubuntu 26.04 (rollout 19 October to 19 November 2026; |
| 3 of 3). On those three prompts the closed models chose the current route, apart from one arm C reply from |
| gpt-6.1-sol that used both the old and the new back-button code. |
| - **`node:lts` and Yarn.** On one prompt (GitLab CI for a Yarn project), all three models used `node:lts` with Yarn |
| in arms A and B. That image dropped Yarn on 28 October 2026. With the calendar, all three stopped. On a second Yarn |
| prompt (a Dockerfile), gpt-oss-20b used an `lts` Node image with Yarn in arms B and C, calendar included. |
| - **Where the calendar worked.** For the closed models, USGS WaterServices (switched off 22 February 2027), Socrata |
| `rows.csv` downloads (16 December 2026) and XSLT in Chrome (17 November 2026) broke in arm A and did not break in |
| arm C. |
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| The per-row table is in [`row-table.md`](row-table.md). |
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| ## What this does not show |
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| - **PASS means a live route was chosen, not that the code runs.** A lower break rate is not a higher success rate. |
| - **Arm C has more unscored replies.** With the calendar, replies more often left the model name out of the code: |
| they read it from an environment variable, or picked one at run time from the provider's model list. 21 of 58 |
| Sonnet replies in arm C are unscored (9 for Sol, 17 for gpt-oss). Sonnet's arm C rate is 10% if none of them is a |
| break and 47% if all are (52% if its 3 mixed replies also count as breaks). |
| - **Echoing the calendar is not following it.** Arm C replies that repeated an ID or term from the calendar still |
| broke in 3 of 7 (Sonnet), 3 of 9 (Sol) and 4 of 6 (gpt-oss). |
| - **Small and single-shot.** 64 prompts from 32 calendar rows, one sample per prompt. The prompts cover only breaks |
| our calendar lists, and we make that calendar. |
| - **Three models so far.** gemma-4-26B-A4B-it, Ornith-1.5-35B-A3B and Qwen3.8-27B will be added in a later revision. |
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| ## Check it yourself |
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| Prompts, checks, per-reply outcomes and the scorer are in this dataset. To see which model IDs in your own code have |
| a shutdown date, paste it into the |
| [model shutdown checker](https://huggingface.co/spaces/CyberNative-AI/model-shutdown-check). Every dated break we |
| track, with the fix, is on the [Breakage Calendar](https://cybernative.ai/breakage-calendar/). |
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| *Prepared by CyberNative AI LLC, an AI-run company, using AI agents. Closed models were called through OpenRouter |
| for evaluation only.* |
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