Lesson 240: Unity Sentis NPC Inference Batch Receipt on BUILD_RECEIPT (2026)

Direct answer: Before summer playtest promotion, file sentis_npc_batch_receipt_v1.json proving max_batch_playtest = 1, CPU backend on min-spec soak, Profiler peak RSS under team cap, and Yarn fallback when Worker.Schedule fails—then promote BUILD_RECEIPT sentis_npc_batch_receipt. Distinct from Sentis deploy preflight (sentis_deploy_receipt_v1) and Lesson 216 dialogue moderation (content policy only).

Why this matters now (June 2027 playtest OOM spikes)

June 2027 playtesters stack tavern dialogue, combat barks, and Sentis classifiers in one scene—laptops with 8 GB RAM OOM while dev machines stay green. Lesson 238 fixes save bleed; Lesson 237 fixes audio Init—this lesson files sentis_npc_batch_receipt_v1 so inference policy is on BUILD_RECEIPT before facilitators scale the cohort.

The Sentis NPC batch playtest preflight is the ninety-second gate—240 is the course milestone. Lesson 216 remains required for generative text changes—orthogonal column.

Beginner path (tavern soak)

Time: ~66 minutes first min-spec soak; ~20 minutes when batch cap is code-pinned.

Developer path (gates N1–N6)

N2–N3 — Playtest inference policy

public BackendType GetPlaytestBackend() => BackendType.CPU;

public int GetPlaytestBatchSize() => 1;

Document in receipt—do not rely on #if DEVELOPMENT_BUILD alone if playtest uses Release profile.

sentis_npc_batch_receipt_v1.json

{
  "schema": "sentis_npc_batch_receipt_v1",
  "build_label": "summer-playtest-2027-rc1",
  "model_id": "npc_intent_v1",
  "max_batch_playtest": 1,
  "backend_playtest": "CPU",
  "concurrent_workers_cap": 2,
  "profiler_peak_rss_mb": 5200,
  "ten_minute_tavern_soak": "pass",
  "fallback_on_failure": "yarn_node_NPC_DIALOGUE_FALLBACK",
  "parent_receipt": "release-evidence/ai/SENTIS_DEPLOY_RECEIPT.json",
  "gates": {
    "N1_deploy_cousin": "pass",
    "N2_batch_cap": "pass",
    "N3_cpu_backend": "pass",
    "N4_profiler_soak": "pass",
    "N5_fallback": "pass",
    "N6_build_receipt": "pass"
  },
  "playtest_inference_ok": true,
  "promotion_allowed": true,
  "cousin_receipts": {
    "ai_dialogue_patch": "release-evidence/ai/AI_DIALOGUE_PATCH_RECEIPT.json"
  }
}

Pin under release-evidence/ai/SENTIS_NPC_BATCH_RECEIPT.json.

BUILD_RECEIPT row (N6)

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

Relationship to guide vs Lesson 216

Key takeaways

1. Deploy GREEN ≠ playtest GREEN—cap batch and backend separately.
2. sentis_npc_batch_receipt_v1 ≠ sentis_deploy_receipt_v1—cousin columns.
3. Lesson 216 — what NPCs say; 240 — how inference runs.
4. Q3 capstone 244 wires 236–243 including this row.
5. ShapeInference help when batch>1 fails compile.
6. CPU-first on 8 GB playtest laptops—promote GPU only with N4 proof.
7. Lesson 238 — saves; 240 — AI inference.
8. Thursday review — AI / Sentis row.

Common mistakes

• Filing from 32 GB dev soak only—min-spec not exercised.
• batch=4 because “tavern has four NPCs”—use concurrent worker cap instead.
• Skipping N5 fallback test—playtest soft-lock on API 529.
• Replacing Lesson 216 with this receipt—both required when generative dialogue ships.
• Merging deploy + batch JSON—schemas stay separate.

Troubleshooting

Mini exercise (60 minutes)

1. Set batch=4—reproduce OOM on 8 GB loaner laptop.
2. Pin batch=1 + CPU—pass N4 soak.
3. Force schedule failure—confirm Yarn fallback (N5).
4. File receipt; BUILD_RECEIPT GREEN.
5. Link parent SENTIS_DEPLOY_RECEIPT.json path in JSON.

Continuity — Q3 2027 summer playtest wave (236–244)

Previous: Lesson 239 — Steam playtest feedback tag taxonomy.
Next: Lesson 241 — Construct playtest analytics event receipt.

FAQ

Same as Sentis batch preflight guide?
Guide = checklist; 240 = BUILD_RECEIPT column.

Same as Sentis deploy receipt?
No—deploy proves compile/ladder; batch proves playtest memory policy.

Need Lesson 216 if only classifiers change?
216 applies when LLM dialogue text changes; batch receipt still required for Sentis path.

Playtest tavern OOM is usually batch policy—cap batch, CPU soak, fallback wired, file sentis_npc_batch_receipt, then promote on BUILD_RECEIPT.