Lesson 249: Blender Hero glTF Export Hash Receipt on BUILD_RECEIPT (2026)

Direct answer: Before July playtest scale promotes fest_public while playtest_invite still runs, file gltf_export_hash_receipt_v1.json proving pinned gltf_export_preset_v1.json, modifier/armature freeze, sha256 on hero_playtest.glb + hero_export_manifest.json, re-export match, engine spot load, and optional cousin fab_8k_throttle_receipt_v1 (Lesson 230) when Fab textures ship—then promote BUILD_RECEIPT gltf_export_hash_ok. Distinct from 230 (8K URI throttle) and Lesson 248 (2D bridge spot).

Why this matters now (July 2027 playtest vs fest_public hero GLB drift)

July 2027 teams hotfix armor UVs on main while playtest-july-rc1 still serves Friday’s .glb. Facilitators report missing pauldrons and wrong material slot 0—engineering proves 8K throttle GREEN but never filed hero export identity. The Blender hero glTF export hash preflight is the ninety-second checklist—249 is the BUILD_RECEIPT milestone for gltf_export_hash per build_label.

Pair Lesson 204 when metallic looks flat despite matching hash, and Lesson 201 when the wrong depot ships the right file.

Beginner path (export → hash → promote)

Time: ~52 minutes first hero pin; ~15 minutes when preset and collection are frozen.

Developer path (gates G1–G6)

G1 — cousin receipt crosswalk

Do not embed T1–T6 throttle proof inside 249 JSON—reference cousin when Fab paths present.

gltf_export_hash_receipt_v1.json

{
  "schema": "gltf_export_hash_receipt_v1",
  "build_label": "playtest-july-2027-rc1",
  "character_id": "hero_combat",
  "gltf_path": "art/characters/hero/hero_playtest.glb",
  "manifest_path": "art/characters/hero/hero_export_manifest.json",
  "export_preset": "tools/blender/gltf_export_preset_v1.json",
  "sha256_bundle": "sha256:REPLACE_AFTER_COMPUTE",
  "reexport_match": true,
  "glb_bytes": 2458624,
  "cousin_receipts": {
    "fab_8k_throttle": "release-evidence/art/FAB_8K_THROTTLE_RECEIPT.json"
  },
  "engine_spot": {
    "engine": "godot_4.5",
    "vertex_count_ok": true,
    "material_slot_0_ok": true
  },
  "gates": {
    "G1_export_preset": "pass",
    "G2_modifier_freeze": "pass",
    "G3_sha256_bundle": "pass",
    "G4_reexport": "pass",
    "G5_engine_spot": "pass",
    "G6_build_receipt": "pass"
  },
  "gltf_export_hash_ok": true,
  "playtest_promotion_allowed": true
}

Pin under release-evidence/art/GLTF_EXPORT_HASH_RECEIPT.json.

BUILD_RECEIPT row (G6)

ALTER TABLE release_publish_gate ADD COLUMN IF NOT EXISTS
  gltf_export_hash_blocked BOOLEAN NOT NULL DEFAULT false;

Thursday row review — Hero GLB hash line: playtest hash = fest hash Y/N.

Key takeaways

1. 230 throttle ≠ 249 export hash—both required for Fab heroes.
2. Hash GLB + manifest together—vertex count drift lives in manifest.
3. build_label must match across playtest_invite and fest_public hero rows.
4. Draco preflight is separate—document draco in manifest.
5. Lesson 248 is 2D—do not conflate columns.
6. playtest_promotion_allowed here ≠ Q4 capstone 253.
7. Re-export without manifest bump blocks facilitators silently.
8. Cousin 204 fixes metallic channels—not missing armor meshes.
9. File receipt before scaling concurrent playtest cohorts.
10. Forward: Lesson 250 VO consent metadata (when published).

Common mistakes

• Promoting fest_public with newer .glb than playtest receipt.
• Hashing .blend instead of exported .glb.
• Draco on playtest only—WebGL SKU decode fail.
• Skipping cousin 230 when hero uses Fab ORM.
• Merging schemas into fab_8k_throttle_receipt_v1.

Troubleshooting

Mini exercise (50 minutes)

1. Export with unstabilized modifier—confirm G4 fail.
2. Pin G1 + G2; pass re-export match.
3. Link cousin FAB_8K_THROTTLE_RECEIPT.json.
4. File receipt; block fest promotion until playtest hash matches.

Continuity — Q4 2027 July playtest scale (245–253)

Previous: Lesson 248 — Aseprite sprite bridge hash spot
Next: Lesson 250 — Audacity VO consent metadata

FAQ

Same as Lesson 230?
230 = 8K texture URIs; 249 = hero GLB + manifest sha256 identity.

Same as export hash guide?
Guide = G1–G6 checklist; 249 = BUILD_RECEIPT promotion.

Same as Lesson 204?
204 = ORM channels; 249 = mesh/material export identity.

Need Draco preflight first?
Only if manifest sets draco: true—keep one policy per build_label.

Playtest and fest_public must share hero .glb identity—pin export, hash bundle, engine spot, cousin 230 when needed, then gltf_export_hash_ok on BUILD_RECEIPT.