{
  "schema": "studycommons.hero.provenance.legacy.v1",
  "asset_role": "Study Commons Daily Read hero",
  "slug": "why-lakes-freeze-from-the-top",
  "generator": "QwenImage21Pipeline",
  "generation_id": "img-df6659ec7d55d51af78683dc",
  "model_id": "Qwen/Qwen-Image-2.1",
  "model_revision": "b3179ad355be050328e483a9dfdd9e60cd62adfa",
  "model_index_sha256": "cf1ecd104ea090855d60d8cec0895c1e9d6ee41b2f87e231b678beecd1cf7809",
  "scheduler_config_sha256": "5895f3a167c14a967fe9ac70c64924ae5acc79799e0679fd12907e594a713cd1",
  "checkpoint_sha256": "7f17c6a21036f6c085010c689172ca62b4a6af197d162494dc35eca6eab811da",
  "checkpoint_weights": [
    {
      "file": "text_encoder/model-00001-of-00004.safetensors",
      "sha256": "dde00291b5f7fb92013895310a3da0ddba78674df9f10d505d375243dc01fc6f",
      "bytes": 4998056552
    },
    {
      "file": "text_encoder/model-00002-of-00004.safetensors",
      "sha256": "9047faccc0a6d98496a52d55f27be1c94a9c259d1e283fbea0128d054a948d42",
      "bytes": 4915962464
    },
    {
      "file": "text_encoder/model-00003-of-00004.safetensors",
      "sha256": "8c54187654c0176b73ae73785bf791dc9a14c9df7fb4310083a09d42048cb57e",
      "bytes": 4915962496
    },
    {
      "file": "text_encoder/model-00004-of-00004.safetensors",
      "sha256": "5311532aaaeae3259eb6a7b2c600636be1159adf7ded35f53579f7d0e7d43cdd",
      "bytes": 2704357976
    },
    {
      "file": "transformer/diffusion_pytorch_model-00001-of-00002.safetensors",
      "sha256": "9e6bc2d641e67bf277895ea8777141044a38f3edb7101bc469b2961dd7c36b4b",
      "bytes": 9968332504
    },
    {
      "file": "transformer/diffusion_pytorch_model-00002-of-00002.safetensors",
      "sha256": "3aaf234dcbe128530479735854a346b5e3e66283b7c11db56f836bbd1c13ebaa",
      "bytes": 4261951904
    },
    {
      "file": "vae/diffusion_pytorch_model.safetensors",
      "sha256": "a07a1b7c4ee2966a1b3bdc37de9b4f983d56937e46619f709a80b6e490675417",
      "bytes": 1350989512
    }
  ],
  "checkpoint_fingerprint_note": "Checkpoint fingerprints recorded during retrospective reproduction, not at first generation; independently reproduced PNG and AVIF are byte-identical to the original approved files.",
  "model_license": "Qwen Research License; non-commercial research/evaluation only. Separate permission required for commercial use.",
  "prompt": "Cinematic educational editorial hero image for a Canadian Grade 4-5 science reading article about why lakes freeze from the top. A realistic winter freshwater lake at dusk with a clear cutaway-style natural perspective: smooth new ice forming across the surface while darker liquid water remains below, subtle trapped bubbles and translucent ice near shore, snowy Canadian shoreline with reeds and conifers, cold blue ambient light with gentle warm twilight on the horizon. Scientifically plausible and visually clear that ice is at the surface while liquid water remains underneath, documentary realism, elegant composition, kid-friendly but not cartoonish, no people, no text, no labels, no infographic arrows, no logos, no watermark. Wide 16:9 composition with the ice-water boundary as the main visual focus and safe margins for responsive crop.",
  "prompt_sha256": "fe36f250e0c6f0a1808e3789bd2e23d1fb1bd09a2d96efc7298ee8becf2f9789",
  "negative_prompt": "text, letters, labels, watermark, logo, split screen, diagram, infographic, cartoon, fantasy, oversaturated, impossible underwater scene, distorted shoreline, duplicated objects",
  "seed": 24092402,
  "num_inference_steps": 20,
  "true_cfg_scale": 4.0,
  "requested_width": 1280,
  "requested_height": 720,
  "actual_width": 1280,
  "actual_height": 704,
  "width": 1280,
  "height": 704,
  "scheduler": "FlowMatchEulerDiscreteScheduler",
  "scheduler_config": {
    "_class_name": "FlowMatchEulerDiscreteScheduler",
    "_diffusers_version": "0.37.0.dev0",
    "base_image_seq_len": 256,
    "base_shift": 0.5,
    "invert_sigmas": false,
    "max_image_seq_len": 8192,
    "max_shift": 0.9,
    "num_train_timesteps": 1000,
    "shift": 1.0,
    "shift_terminal": 0.02,
    "stochastic_sampling": false,
    "time_shift_type": "exponential",
    "use_beta_sigmas": false,
    "use_dynamic_shifting": true,
    "use_exponential_sigmas": false,
    "use_karras_sigmas": false
  },
  "generator_device": "cuda",
  "generator_algorithm": "torch.Generator(device='cuda:0').manual_seed(seed)",
  "torch_dtype": "bfloat16",
  "cpu_offload": "model",
  "vae_tiling": false,
  "use_kv_cache": true,
  "lora": null,
  "reference_images": [],
  "gpu": "CUDA GPU (device-specific details intentionally excluded)",
  "output_png_sha256": "df6659ec7d55d51af78683dc5df981b14f3d86967b159abcc1f94312eab5d6e0",
  "postprocess": {
    "format": "AVIF",
    "encoder": "libaom-av1",
    "filter": "scale=1280:720:force_original_aspect_ratio=increase:flags=lanczos,crop=1280:720",
    "still_picture": 1,
    "crf": 1,
    "bitrate": 0,
    "cpu_used": 6,
    "pix_fmt": "yuv420p",
    "frames": 1,
    "ffmpeg_version": "ffmpeg version 6.1.1-3ubuntu5",
    "source_png_sha256": "df6659ec7d55d51af78683dc5df981b14f3d86967b159abcc1f94312eab5d6e0",
    "output_avif_sha256": "9525d0539b578985bf2a767d42205caaa061fb6d4f46090a1531cfd3df80201b",
    "output_avif_width": 1280,
    "output_avif_height": 720,
    "output_avif_bytes": 215377
  },
  "reproduction_verification": {
    "verified_at": "2026-10-13T20:02:08.022724+00:00",
    "runtime": {
      "torch": "2.14.0+cu130",
      "diffusers": "0.41.0.dev0",
      "transformers": "5.17.0",
      "cuda": "13.0"
    },
    "model_revision": "b3179ad355be050328e483a9dfdd9e60cd62adfa",
    "png_byte_identical": true,
    "avif_byte_identical": true,
    "original_generation_runtime": "not independently recorded at the original generation",
    "original_publication_date": "2026-09-25",
    "verification_notes": "Source job, selected candidate, existing asset and a fresh inference run were compared by SHA-256. The same source checkpoint and runtime recreated byte-identical PNG and AVIF."
  },
  "reproduce": {
    "script": "tools/reproduce_legacy_hero.py",
    "command": "python3 tools/reproduce_legacy_hero.py --provenance hero-provenance.json --model-dir MODEL_DIR --png replay.png --avif replay.avif --strict-hash",
    "requirements": "Licensed Qwen Image 2.1 checkpoint, CUDA-capable environment, Diffusers, Transformers, PyTorch and FFmpeg. Version details are in reproduction_verification.runtime."
  },
  "provenance_note": "This record supports independent generation verification and file integrity, not proof of copyright ownership or a commercial license. Unavailable original runtime metadata is declared, not fabricated."
}