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    "story_id": "mp-2026-09-15-010",
    "source_story_id": "tmp-story-fraglingo-open-fragment-vocabulary",
    "edition_id": "mp-2026-09-15-morning-0068",
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    "headline": "The Molecule Builder Added New Fragments Without Retraining",
    "slug": "the-molecule-builder-added-new-fragments-without-retraining",
    "dek": "Fraglingo jointly predicts fragment identity and attachment and generalized to inference libraries four times larger than its training vocabulary.",
    "summary": "Fraglingo jointly predicts fragment identity and attachment and generalized to inference libraries four times larger than its training vocabulary.",
    "body_text": "Fragment-based molecular generators often choose a fragment from a fixed vocabulary and predict its attachment separately. Fraglingo represents both decisions in one attachment-aware continuous embedding, retrieves the next fragment by nearest-neighbor search and encodes the growing molecule from its active attachment site. Because inference operates over embeddings rather than fixed identifiers, new fragments can be added without retraining. The authors report stronger joint property control than comparable baselines and generalization to fragment libraries four times larger than the training set. Computational benchmarks do not establish laboratory synthesis or drug efficacy.",
    "why_it_matters": "Fraglingo jointly predicts fragment identity and attachment and generalized to inference libraries four times larger than its training vocabulary.",
    "limitations": [
      "Computational benchmarks do not establish laboratory synthesis or drug efficacy."
    ],
    "importance": 8,
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    "first_published_at": "2026-09-15T09:00:00.000-04:00",
    "modified_at": "2026-09-15T09:00:00.000-04:00",
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        "text": "Fraglingo jointly predicts fragment identity and attachment and generalized to inference libraries four times larger than its training vocabulary.",
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        "qualification": "Computational benchmarks do not establish laboratory synthesis or drug efficacy."
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    "source_ids": [
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    "tags": [
      "molecular design",
      "generative models",
      "fragment libraries"
    ],
    "image_url": null,
    "corrections": []
  },
  "sources": [
    {
      "source_id": "source-2026-09-15-010",
      "title": "arXiv preprint 2609.13519",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.13519",
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      "source_type": "primary_research",
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      "published_at": "2026-09-13T20:00:00.000-04:00",
      "accessed_at": "2026-09-15T08:18:00.000-04:00",
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  "publisher": {
    "name": "The Machine Press",
    "url": "https://themachinepress.com",
    "description": "A daily newspaper for the age of artificial intelligence."
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  "cite_this_report": {
    "title": "The Molecule Builder Added New Fragments Without Retraining",
    "publisher": "The Machine Press",
    "published_at": "2026-09-15T09:00:00.000-04:00",
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