{
  "schema": "studycommons.hero.provenance.v2",
  "asset_role": "Study Commons public Daily Read hero",
  "slug": "why-lightning-before-thunder",
  "generation_id": "img-41f3d72df352387126d8e177",
  "generator": "QwenImage21Pipeline",
  "model": "Qwen/Qwen-Image-2.1-Turbo",
  "model_revision": "fc13ba1986fcb905854dc8de2f52eee395f49b5b",
  "model_license": "Qwen Research License, non-commercial research/evaluation only; commercial use requires separate permission",
  "model_index_sha256": "97e2febeb19d93cb41fa44807cde8bd42757950b5dffeacdb0331fb2d390cf20",
  "checkpoint_sha256": "37230cd77d377c0be0acc06d628fd8a6e978e23eb2c530b73fa98df54ef62557",
  "renderer_source_sha256": "18b5d04715eadcb1d3672ba2b4f1af5da95fb9f8ebfdea97b3add250b08712c9",
  "prompt": "Create one premium editorial hero illustration for a public English elementary learning article. Article title: Why Do We See Lightning Before We Hear Thunder? Context: Explain why a lightning flash reaches your eyes before thunder reaches your ears, how thunder forms, why it can rumble, and how the flash-to-thunder delay gives only an approximate distance. Specific scene: Distant lightning in a real storm cloud over a landscape as seen safely through a home window, natural blue-gray lighting. No visual sound-wave arrows. Accurate observable details, physically plausible scene, honest proportions and natural lighting, restrained polished photography, age-appropriate, one clear focal point, clean composition. Wide 16:9 framing, safe margins, no collage or split panels unless required by the scene. No text, legible labels, numbers, equations, graphs, callouts, arrows, logos or watermarks. This is only a visual hero, NOT a scientific instructional diagram and NOT experimental evidence.",
  "prompt_sha256": "2126f48bb72546f2d438cde7edd618d4ea46f9ca747d49071cd37c8f76ad00aa",
  "negative_prompt": "",
  "seed": 502919520,
  "width": 1312,
  "height": 736,
  "num_inference_steps": 8,
  "true_cfg_scale": 1.0,
  "scheduler": "FlowMatchEulerDiscreteScheduler",
  "sampling": "explicit-checkpoint-8-sigma",
  "sample_sigmas": [
    1.0,
    0.978453,
    0.95418,
    0.926626,
    0.89508,
    0.845148,
    0.704534,
    0.414568
  ],
  "generator_device": "cpu",
  "generator_algorithm": "torch.Generator('cpu').manual_seed(seed)",
  "torch_dtype": "bfloat16",
  "cpu_offload": "model",
  "use_kv_cache": true,
  "vae_tiling": true,
  "lora": null,
  "reference_images": [],
  "gpu": "NVIDIA CUDA (hardware-specific machine details withheld)",
  "runtime": {
    "torch": "2.14.0+cu130",
    "diffusers": "0.41.0.dev0",
    "transformers": "5.17.0",
    "cuda": "13.0"
  },
  "job_completed_at": "2026-10-13T23:26:26.942752+00:00",
  "output_png_sha256": "41f3d72df352387126d8e177dfb98c0584743da94f19f8a0102565a4156ca86e",
  "output_png_dimensions": [
    1312,
    736
  ],
  "postprocess": {
    "format": "AVIF",
    "ffmpeg_version": "ffmpeg version 6.1.1-3ubuntu5",
    "filter": "scale=1280:720:force_original_aspect_ratio=increase:flags=lanczos,crop=1280:720",
    "encoder": "libaom-av1",
    "still_picture": 1,
    "crf": 1,
    "bitrate": "0",
    "cpu_used": 6,
    "pix_fmt": "yuv420p",
    "frames": 1,
    "source_png_sha256": "41f3d72df352387126d8e177dfb98c0584743da94f19f8a0102565a4156ca86e",
    "output_avif_sha256": "4faa4a052edcecdae8da2f6c37e39e8a9ef1959104bd410c33c24462c25aaf6b",
    "output_avif_width": 1280,
    "output_avif_height": 720,
    "output_avif_bytes": 209068
  },
  "reproduce": {
    "recipe": "QwenImage21Pipeline.from_pretrained(model_path, dtype=torch.bfloat16); enable_model_cpu_offload(); vae.enable_tiling(); pipeline(prompt=prompt, width=width, height=height, true_cfg_scale=1.0, num_inference_steps=8, sigmas=sample_sigmas, use_kv_cache=True, generator=torch.Generator('cpu').manual_seed(seed)); encode PNG to AVIF using postprocess fields",
    "model_source": "Hugging Face model ID and exact model_revision above, subject to the stated license",
    "verification": "Compare generated image and encoded AVIF with the corresponding SHA-256 values above. Pixel-identical results are not guaranteed across devices or software builds."
  },
  "provenance_note": "This is an exact generation-parameter record and cryptographic integrity chain, not a legal ownership certificate or guarantee of third-party rights. Full private machine/job metadata is excluded."
}