Lesson 238: Godot Playtest Save Isolation Receipt on BUILD_RECEIPT (2026)

Direct answer: Before you open a June playtest wave while fest_public stays live, file playtest_save_isolation_receipt_v1.json proving playtest and fest Godot builds use different user:// save roots, pass the installed Steam isolation matrix, and crosswalk save_slot_label_map per surface on BUILD_RECEIPT playtest_save_isolation. Distinct from Lesson 212 save slot labels (UI ↔ Cloud names) and Lesson 237 Wwise init.

Why this matters now (June 2027 dual-branch playtest)

June 2027 teams pass Wwise init rows and invite facilitators on playtest_june while the fest demo depot remains on fest_public. Godot’s default persistence is per executable, not per Steam branch—playtesters save chapter 7, launch the fest build, and see the wrong slot. Lesson 212 fixes label drift; playtest isolation playbook sets depot policy—this lesson files playtest_save_isolation_receipt_v1 on BUILD_RECEIPT.

The Godot save isolation preflight is the ninety-second checklist—238 is the course milestone.

Beginner path (isolation matrix)

Time: ~64 minutes first dual-depot wiring; ~15 minutes when autoload is pinned.

Developer path (gates I1–I6)

I1 — Surface path map (reference)

# scripts/save_surface_paths.gd — autoload SavePaths
const SURFACE_PATHS := {
    "playtest_invite": "user://saves_playtest/",
    "fest_public": "user://saves_fest/",
}

CI: SAVE_SURFACE=playtest_invite on playtest depot job; fest_public on fest job.

I2 — Per-surface label maps

Extend Lesson 212 maps with save_root—do not duplicate UI labels without path roots.

playtest_save_isolation_receipt_v1.json

{
  "schema": "playtest_save_isolation_receipt_v1",
  "build_label": "playtest-june-2027-rc1",
  "surfaces": {
    "playtest_invite": {
      "save_root": "user://saves_playtest/",
      "save_slot_label_map": "release-evidence/saves/PLAYTEST_SAVE_SLOT_LABEL_MAP.json"
    },
    "fest_public": {
      "save_root": "user://saves_fest/",
      "save_slot_label_map": "release-evidence/saves/FEST_SAVE_SLOT_LABEL_MAP.json"
    }
  },
  "isolation_matrix": {
    "playtest_slot2_roundtrip": "pass",
    "fest_slot2_cross_contamination": "none",
    "playtest_relaunch_slot2": "pass"
  },
  "gates": {
    "I1_surface_path_map": "pass",
    "I2_label_map_crosswalk": "pass",
    "I3_playtest_roundtrip": "pass",
    "I4_fest_no_playtest_files": "pass",
    "I5_cloud_prefix": "pass",
    "I6_build_receipt": "pass"
  },
  "isolation_ok": true,
  "promotion_allowed": true,
  "cousin_receipts": {
    "save_slot_label": "release-evidence/saves/SAVE_SLOT_LABEL_RECEIPT.json"
  }
}

Pin under release-evidence/saves/PLAYTEST_SAVE_ISOLATION_RECEIPT.json.

BUILD_RECEIPT row (I6)

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

Relationship to guide vs Lesson 212

Key takeaways

1. Branch isolation needs path roots, not only separate Steam depots.
2. Pair 212 (labels) with 238 (paths)—both columns on BUILD_RECEIPT.
3. Lesson 237 — audio; 238 — Godot persistence.
4. Prove on installed playtest + fest builds—not Editor-only.
5. Q3 capstone 244 wires 236–243 including this row.
6. Thursday review — one Saves / isolation line.
7. SAVE_SURFACE must be set in CI per depot job.
8. Never copy playtest saves into fest folder “for debug”—invalidates I4.

Common mistakes

• Green 212 but shared user://—labels OK, paths wrong.
• Testing only in Editor—SAVE_SURFACE unset masks bug.
• Same Steam Cloud remote name on both surfaces—I5 fail.
• Skipping fest relaunch after playtest save—I4 never exercised.
• Conflating with Deck static menu—GPU, not saves.

Troubleshooting

Mini exercise (60 minutes)

1. Ship one build without SAVE_SURFACE—reproduce fest bleed.
2. Add autoload + per-surface maps—pass I1–I2.
3. Run isolation matrix on two Steam installs.
4. File receipt; BUILD_RECEIPT GREEN.
5. Link playtest isolation blog in facilitator SOW.

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

Previous: Lesson 237 — Wwise DSP init boot path.
Next: Lesson 239 — Steam playtest feedback tag taxonomy.

FAQ

Same as Godot save isolation guide?
Guide = checklist; 238 = BUILD_RECEIPT column.

Same as Lesson 212?
212 = labels/Cloud; 238 = per-branch save roots + isolation matrix.

Unity project?
Apply same surface → path pattern; receipt schema is engine-agnostic on BUILD_RECEIPT.

Need both 212 and 238 GREEN?
Yes when multi-slot saves ship on multiple Steam surfaces.

Dual-branch playtests fail when fest saves absorb playtest progress—isolate paths, prove the matrix on Steam installs, then promote on BUILD_RECEIPT.