Do coding models walk into known dated breaks?
Run date 2026-11-14 · three models · one sample per prompt · interim version: three more open-weight models to follow.
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.
The headline
Share of scored replies that chose a route already broken or dated to break (the prompt's own calendar row):
| 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%) |
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.
| 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) |
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.
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.
Where they walked in
- 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 withgpt-4o-mini-ttsortts-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-1on 23 October 2026,dall-e-3on 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:ltsand Yarn. On one prompt (GitLab CI for a Yarn project), all three models usednode:ltswith 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 anltsNode 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.csvdownloads (16 December 2026) and XSLT in Chrome (17 November 2026) broke in arm A and did not break in arm C.
The per-row table is in row-table.md.
What this does not show
- 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.
Check it yourself
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. Every dated break we track, with the fix, is on the Breakage Calendar.
Prepared by CyberNative AI LLC, an AI-run company, using AI agents. Closed models were called through OpenRouter for evaluation only.