{
 "goal": "Reformat both Tier-2 binders into gut-restricted, orally-deliverable, non-absorbed formats that engage their epithelial-surface targets in the gut lumen/mucosa without systemic exposure.",
 "target_depth_assessment": {
  "NKG2D_MIC": {
   "location": "MIC (MICA/MICB) is a stress-induced ligand on the APICAL surface of gut epithelial cells; NKG2D is on IELs/NK at the epithelial surface. The killing synapse sits at the epithelial surface.",
   "depth": "surface",
   "gut_restriction_fit": "FAVORABLE \u2014 a luminally-delivered decoy can reach MIC on the epithelial apical face."
  },
  "IL15": {
   "location": "IL-15 is trans-presented by IL-15R\u03b1 on epithelial and myeloid cells to IELs at the epithelial/intraepithelial interface (our single-cell data: IL15 dominant in endothelial/stromal, trans-presented at the surface).",
   "depth": "surface-to-submucosal",
   "gut_restriction_fit": "MODERATE \u2014 surface trans-presentation is reachable; a submucosal pool may be less accessible (flagged)."
  }
 },
 "format_path": {
  "step1_domain_minimization": {
   "mica_decoy": "Current scaffold is the full MICA \u03b11\u03b12 platform (275 aa). Minimize to the \u03b11\u03b12 \u03b2-sheet platform bearing the 29 NKG2D-contact residues; the \u03b13 Ig domain and TM/cytoplasmic remnants are dispensable for the decoy function. Target ~180\u2013190 aa single domain.",
   "il15_binder": "Current scaffold is the IL-2R\u03b2 D1 domain (202 aa). Already a single Ig-like domain; trim disordered termini to the folded core (~150\u2013160 aa)."
  },
  "step2_VHH_reformatting": {
   "rationale": "Camelid single-domain antibodies (VHH/nanobodies, ~13 kDa) are the reference gut-stable format: they fold without a partner chain, tolerate low pH, resist proteases better than conventional Fabs, and are non-absorbed across an intact epithelium. Precedents: oral anti-TNF VHH (V565) reached the inflamed gut lumen intact in clinical testing.",
   "path": "Graft the fixed interface epitope (the 29 MICA / 12 IL-15 contact residues) onto a stable VHH framework by transplanting the paratope-defining residues onto CDR-supporting loop positions, OR raise/scaffold a de novo VHH against the same epitope. Deliverable here = the epitope residue set + grafting specification; the folded VHH model requires GPU (RFdiffusion/AlphaFold-multimer)."
  },
  "step3_protease_hardening": "Apply the interface-preserving hardening from this campaign (omit K/R/F/W/Y/M outside the paratope) to the VHH framework regions \u2014 45\u201349% harden-target-site reduction demonstrated on the current scaffolds.",
  "step4_disulfide_lock": "Retain/engineer the canonical VHH framework disulfide (Cys22\u2013Cys92) plus any structural Cys pairs (5 retained in MICA-hardened, 3 in IL-15-hardened) to raise thermodynamic and proteolytic stability in the gut.",
  "step5_mucin_anchoring": {
   "rationale": "To prolong mucosal residence and further prevent washout/absorption, fuse a mucus/epithelium-anchoring module.",
   "options": [
    "CBM (carbohydrate-binding module) or mucin-binding protein (MUB) domain fusion for mucus retention",
    "A short polycationic or mucoadhesive peptide tag (balanced against the already-negative net charge)",
    "Fc-free multivalency (tandem VHH) to increase avidity for surface MIC/IL-15 without adding absorbable mass"
   ]
  }
 },
 "non_absorption_rationale": {
  "size": "VHH ~13 kDa is above the paracellular cutoff of an intact epithelium; tandem/anchored formats larger still.",
  "charge": "Hardened designs are strongly net-negative (MICA \u221242, IL-15 \u221226), which disfavors transcellular membrane permeation \u2014 a bonus of the K/R-omit hardening.",
  "combined": "Size + charge + mucin anchoring \u2192 luminal/mucosal retention with minimal systemic absorption, the gut-restriction goal."
 },
 "honest_limitations": [
  "No GPU in this environment: the VHH graft is specified at the epitope/residue level, not folded or co-folded; ipTM against target not computed.",
  "Protease rules are PeptideCutter-style sequence predictions, not empirical digestion; elastase liability is intrinsic to any folded chain.",
  "Very negative net charge aids non-absorption but must be checked for folding/solubility and for interfering with the (often charged) binding interface.",
  "IL-15 submucosal pool may be less accessible to a purely luminal agent (target-depth caveat)."
 ]
}