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    "story_id": "mp-2026-09-03-003",
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    "headline": "The Web Agent Predicted Differences, Not Just Pages",
    "slug": "the-web-agent-predicted-differences-not-just-pages",
    "dek": "A matching objective trains predicted states to separate the true result of an action from the states produced by alternatives.",
    "summary": "A matching objective trains predicted states to separate the true result of an action from the states produced by alternatives.",
    "body_text": "Most web-agent world models learn to reproduce the next HTML or accessibility-tree snapshot, even though the downstream ranker needs to tell candidate actions apart. The new objective uses branching WebArena Go-Browse trajectories with multiple actions and resulting states at each decision point. The authors report better predicted-state matching, action ranking on WebPRMBench and end-to-end success on WebArena-Lite than action-only or supervised-next-state comparisons.",
    "why_it_matters": "A matching objective trains predicted states to separate the true result of an action from the states produced by alternatives.",
    "limitations": [
      "The authors report better predicted-state matching, action ranking on WebPRMBench and end-to-end success on WebArena-Lite than action-only or supervised-next-state comparisons."
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    "first_published_at": "2026-09-03T09:00:00.000-04:00",
    "modified_at": "2026-09-03T14:20:28.218-04:00",
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        "text": "A matching objective trains predicted states to separate the true result of an action from the states produced by alternatives.",
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        "qualification": "The authors report better predicted-state matching, action ranking on WebPRMBench and end-to-end success on WebArena-Lite than action-only or supervised-next-state comparisons."
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    "tags": [
      "web agents",
      "world models",
      "action ranking"
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  "sources": [
    {
      "source_id": "source-2026-09-03-003",
      "title": "arXiv preprint 2609.02885",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.02885",
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      "source_type": "primary_research",
      "is_primary_source": true,
      "published_at": "2026-09-02T13:59:40.000-04:00",
      "accessed_at": "2026-09-03T14:20:28.218-04:00",
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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 Web Agent Predicted Differences, Not Just Pages",
    "publisher": "The Machine Press",
    "published_at": "2026-09-03T09:00:00.000-04:00",
    "canonical_url": "https://themachinepress.com/story/mp-2026-09-03-003/the-web-agent-predicted-differences-not-just-pages"
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