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Sundial: 85.2% of fixes compile vs 80.7% for a frontier model

Sundial (software, <50 employees) reported this on 16 Sep 2026 in company self-report (source). It belongs to the learning loop layer.

What they built

TeXtinguisher, a fine-tuned Inkling-Small (SFT then GRPO on Tinker) that fixes LaTeX compile errors inside the editor, trained on 3,978 real error/fix pairs mined from TeX.StackExchange.

The result

85.2% of fixes compile vs 80.7% for GPT-5.5 and 82.4% for Claude Fable 5.1, at 0.95 s median vs 2.47-5.72 s; within six points of GPT-6 Astra at a fourteenth of its cost.

The number covers 647 held-out real single-file errors.

The layer: The learning loop

Reviewed corrections are kept as test cases and later used to train models.

  • A log of every correction and who reviewed it
  • Eval sets that grow from reviewed corrections
  • New versions, then post-trained models, from that signal

Read the guide to the learning loop.

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  • 13.8x

    lower cost per task, with higher accuracy than the best frontier model

    A Qwen3-235B model fine-tuned on Tinker with investor-labelled data to do six daily information-filtering tasks (e.g. which news matters to a macro investor) (source).

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    A proof of value on Red Hat OpenShift AI: GPT-4.1 generated synthetic training data, then small models (Phi-4 Mini 3.8B, Qwen 2.5 1.5B/7B) were fine-tuned for multilingual structured extraction from social media, deployable locally (source).

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