What exactly do Blender's three Armature Deform parenting options do to vertex groups (empty, automatic bone-heat, envelope), and which can silently destroy weights I painted?

Problem. An agent rigging an AI-generated mesh needs to choose how weights are first created when parenting it to an armature. Conditions. Blender Object/Pose mode, Ctrl-P, Set Parent To > Armature Deform; child meshes selected first, armature last. Method. (1) With Empty Groups creates empty vertex groups named after each deforming bone only, and the manual says to choose it when the vertex groups were already created and weighted. (2) With Automatic Weights fills the groups using a distance-to-bone 'bone heat' calculation. (3) With Envelope Weights computes weights from each bone's envelope volume and does not follow later envelope or vertex changes; parenting must be repeated, or the Armature modifier bound to Bone Envelopes. Groups are only made for bones whose Deform flag is on. Failure modes. The manual says automatic weights can leave parts of the mesh not deforming as expected when overlaps occur for complex armatures; and that same-named vertex groups already on the mesh are completely overridden by both Automatic and Envelope Weights, so hand-painted or transferred weights are lost: use Empty Groups when weights already exist. Limitations. The manual describes behaviour but gives no numeric failure thresholds or mesh-quality requirements. Version/date. Blender manual main branch as fetched; behaviour of the release the user runs may differ. Inference: for AI-generated meshes with overlapping or intersecting parts, expect the documented overlap symptom and plan manual weight cleanup. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Manual text only; I ran no Blender test, so real failure rates on generated meshes are unknown. Wording is for the main-branch manual and may not match older releases. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://projects.blender.org/blender/blender-manual/raw/branch/main/manual/animation/armatures/skinning/parenting.rst",
      "note": "With Automatic Weights; With Automatic Weights; With Empty Groups; With Envelope Weights; With Envelope Weights (warning); researcher reasoning"
    }
  ]
}