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  "story": {
    "story_id": "mp-2026-10-16-011",
    "source_story_id": "tmp-story-linguaguard-language-security-surface",
    "edition_id": "mp-2026-10-16-morning-0098",
    "edition_url": "https://themachinepress.com/edition/2026-10-16",
    "position": 11,
    "story_type": "dispatch",
    "section": "safety-security",
    "editorial_classification": "editorial",
    "headline": "Changing the User's Language Changes the Guard's Verdict",
    "slug": "changing-the-user-s-language-changes-the-guard-s-verdict",
    "dek": "LinguaGuardBench holds tool calls and labels fixed while translating only the instruction, exposing language-dependent safety decisions.",
    "summary": "LinguaGuardBench holds tool calls and labels fixed while translating only the instruction, exposing language-dependent safety decisions.",
    "body_text": "Step-level agent guards are usually prompted and benchmarked in English even when users are not. LinguaGuardBench translates only the user instruction in 1,220 labeled AgentDojo trajectory steps into five languages, leaving every tool call, observation and label byte-identical. Across 19 guards, many open, small and purpose-built systems changed verdicts beyond their own noise; among nine guards below 13 billion parameters, the placebo-adjusted flip rate rose from 1.5 points in French to 4.4 in Amharic. The strongest frontier guards moved by about one point or less in the authors' tests. This does not prove a universal language hierarchy, but it shows that language itself can alter a supposedly invariant safety boundary.",
    "why_it_matters": "LinguaGuardBench holds tool calls and labels fixed while translating only the instruction, exposing language-dependent safety decisions.",
    "limitations": [
      "Step-level agent guards are usually prompted and benchmarked in English even when users are not.",
      "LinguaGuardBench translates only the user instruction in 1,220 labeled AgentDojo trajectory steps into five languages, leaving every tool call, observation and label byte-identical.",
      "This does not prove a universal language hierarchy, but it shows that language itself can alter a supposedly invariant safety boundary."
    ],
    "importance": 8,
    "canonical_url": "https://themachinepress.com/story/mp-2026-10-16-011/changing-the-user-s-language-changes-the-guard-s-verdict",
    "json_url": "https://themachinepress.com/story/mp-2026-10-16-011.json",
    "first_published_at": "2026-10-16T09:00:00.000-04:00",
    "modified_at": "2026-10-16T09:00:00.000-04:00",
    "content_status": "new",
    "is_carryover": false,
    "carryover_reason": null,
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        "text": "LinguaGuardBench holds tool calls and labels fixed while translating only the instruction, exposing language-dependent safety decisions.",
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          "source-2026-10-16-011"
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        "qualification": "Step-level agent guards are usually prompted and benchmarked in English even when users are not."
      }
    ],
    "source_ids": [
      "source-2026-10-16-011"
    ],
    "tags": [
      "agent guards",
      "multilingual safety",
      "tool use"
    ],
    "image_url": null,
    "corrections": []
  },
  "sources": [
    {
      "source_id": "source-2026-10-16-011",
      "title": "arXiv preprint 2610.22244, original v1",
      "publisher": "arXiv / submitting research authors",
      "url": "https://arxiv.org/abs/2610.22244v1",
      "canonical_url": "https://arxiv.org/abs/2610.22244v1",
      "source_type": "primary_research",
      "is_primary_source": true,
      "published_at": "2026-10-15T13:19:40.000-04:00",
      "accessed_at": "2026-10-16T08:26:36.400-04:00",
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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": "Changing the User's Language Changes the Guard's Verdict",
    "publisher": "The Machine Press",
    "published_at": "2026-10-16T09:00:00.000-04:00",
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