{
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  "story": {
    "story_id": "mp-2026-10-20-003",
    "source_story_id": "tmp-story-functional-cad-mechanisms",
    "edition_id": "mp-2026-10-20-morning-0102",
    "edition_url": "https://themachinepress.com/edition/2026-10-20",
    "position": 3,
    "story_type": "dispatch",
    "section": "developer-tools",
    "editorial_classification": "editorial",
    "headline": "The CAD Assembly Has to Move, Not Merely Look Right",
    "slug": "the-cad-assembly-has-to-move-not-merely-look-right",
    "dek": "FunCAD-Harness turns underspecified mechanism requests into candidate-specific physical tests, then uses simulation failures to guide revisions.",
    "summary": "FunCAD-Harness turns underspecified mechanism requests into candidate-specific physical tests, then uses simulation failures to guide revisions.",
    "body_text": "A plausible rendering can conceal a mechanism that cannot perform its job. FunCAD-Harness asks agents to construct and revise mechanisms against physical simulation, generating tests for each candidate rather than matching one reference geometry. Its benchmark spans 46 mechanism families with interdependent, multistep operation. The authors report that the harness exposed failures invisible to visual inspection and improved functional success over evaluated simulation-assisted baselines. It does not certify generated designs for manufacture, but it moves CAD evaluation from appearance toward behavior.",
    "why_it_matters": "FunCAD-Harness turns underspecified mechanism requests into candidate-specific physical tests, then uses simulation failures to guide revisions.",
    "limitations": [
      "A plausible rendering can conceal a mechanism that cannot perform its job.",
      "It does not certify generated designs for manufacture, but it moves CAD evaluation from appearance toward behavior."
    ],
    "importance": 9,
    "canonical_url": "https://themachinepress.com/story/mp-2026-10-20-003/the-cad-assembly-has-to-move-not-merely-look-right",
    "json_url": "https://themachinepress.com/story/mp-2026-10-20-003.json",
    "first_published_at": "2026-10-20T09:00:00.000-04:00",
    "modified_at": "2026-10-20T09:00:00.000-04:00",
    "content_status": "new",
    "is_carryover": false,
    "carryover_reason": null,
    "key_claims": [
      {
        "claim_id": "claim-mp-2026-10-20-003-001",
        "text": "FunCAD-Harness turns underspecified mechanism requests into candidate-specific physical tests, then uses simulation failures to guide revisions.",
        "source_ids": [
          "source-2026-10-20-003"
        ],
        "qualification": "A plausible rendering can conceal a mechanism that cannot perform its job."
      }
    ],
    "source_ids": [
      "source-2026-10-20-003"
    ],
    "tags": [
      "CAD",
      "simulation",
      "mechanism design",
      "agents"
    ],
    "image_url": "https://themachinepress.com/issues/2026-10-20/functional-cad-robot.webp",
    "corrections": []
  },
  "sources": [
    {
      "source_id": "source-2026-10-20-003",
      "title": "arXiv preprint 2610.26861, original v1",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2610.26861v1",
      "canonical_url": "https://arxiv.org/abs/2610.26861v1",
      "source_type": "primary_research",
      "is_primary_source": true,
      "published_at": "2026-10-19T13:59:58.000-04:00",
      "accessed_at": "2026-10-20T08:15:06.176-04:00",
      "supports_claim_ids": [
        "claim-mp-2026-10-20-003-001"
      ]
    }
  ],
  "corrections": [],
  "publisher": {
    "name": "The Machine Press",
    "url": "https://themachinepress.com",
    "description": "A daily newspaper for the age of artificial intelligence."
  },
  "cite_this_report": {
    "title": "The CAD Assembly Has to Move, Not Merely Look Right",
    "publisher": "The Machine Press",
    "published_at": "2026-10-20T09:00:00.000-04:00",
    "canonical_url": "https://themachinepress.com/story/mp-2026-10-20-003/the-cad-assembly-has-to-move-not-merely-look-right"
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}