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Lesson 203: FMOD WebGL Snapshot Registration Boot Probe for Browser Demo (2026)

Direct answer: On FMOD 2.03 WebGL, bus snapshots stay silent when you register snapshots before banks finish loading—or skip the user-gesture resume that unlocks the audio thread. This lesson ships fmod_webgl_snapshot_receipt_v1.json with W1–W6 gates and wires them into your live-ops chain after Lesson 202 string table smoke.

Lesson hero for FMOD WebGL snapshot registration boot probe

Why this matters now (FMOD 2.03 WebGL upgrades)

July–October 2026 HTML5 fest demos upgrade FMOD for Unity 2.03 while desktop builds still duck combat music correctly. WebGL fails differently from banks missing after Addressables strip: banks load, snapshots never apply on the first scene. The FMOD 2.03 WebGL snapshot playbook documents W1–W6; WebGL silent first scene help covers gesture + bus init—this lesson is the course milestone that files the receipt before BUILD_RECEIPT promotion (Help #10 snapshot fix queued separately).

Beginner path (35-minute proof)

Step Action Success check
1 Pin Studio + integration versions in repo fmod_studio_version in receipt
2 Load banks async; wait complete Build Report lists .bank assets
3 Register snapshot list after load W3_snapshot_list pass
4 Add canvas pointerdown gesture gate W4_gesture_resume pass
5 Enter Combat snapshot; measure duck ±1 dB vs Windows
6 Write fmod_webgl_snapshot_receipt_v1.json promotion_allowed: true
7 Attach to BUILD_RECEIPT webgl_snapshot_receipt column green

Time: ~35 minutes smoke; full lesson 70 minutes with CI A/B + triple-surface matrix.

Developer path (gates W1–W6)

Gate Check Fail when
W1 Integration package pinned Hand-copied .bank from Discord
W2 Banks in player / WebGL payload Strip removed banks
W3 Snapshot list registered post-load Awake() registration
W4 Gesture resumes FMOD + browser audio Autoplay block silent
W5 Combat snapshot auditions on WebGL Desktop-only duck proof
W6 Receipt committed + BUILD_RECEIPT Any W1–W5 red

fmod_webgl_snapshot_receipt_v1.json

{
  "schema": "fmod_webgl_snapshot_receipt_v1",
  "build_label": "html5-nextfest-2026-rc2",
  "fmod_studio_version": "2.03.xx",
  "integration_package": "FMOD for Unity 2.03.y",
  "surfaces": {
    "windows_standalone": { "snapshot_combat_duck_db": -6.2, "pass": true },
    "webgl": { "snapshot_combat_duck_db": -5.8, "pass": true }
  },
  "gates": {
    "W1_integration_pin": "pass",
    "W2_banks_loaded": "pass",
    "W3_snapshot_list": "pass",
    "W4_gesture_resume": "pass",
    "W5_snapshot_audition": "pass",
    "W6_receipt": "pass"
  },
  "gesture_probe": "pointerdown_on_canvas",
  "promotion_allowed": true
}

Store under release-evidence/audio/FMOD_WEBGL_SNAPSHOT_RECEIPT.json.

Bank → snapshot → gesture sequence (Unity sketch)

async void Start() {
  await LoadAllBanksAsync(); // W2 complete
  RegisterSnapshotCallbacks(); // W3 — never in Awake before banks
  await WaitForFirstGestureOnCanvas(); // W4
  RuntimeManager.StudioSystem.setParameterByName("Combat", 1f);
  // W5: log bus meter delta vs menu baseline
}

Pair with Wednesday demo smoke before HTML5 branch promotion.

Publish gate

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

CI verify_fmod_webgl_snapshot_v1 sets blocked false only when promotion_allowed is true and Thursday row review includes webgl_snapshot_receipt if your template extended audio columns.

Prerequisites

Common mistakes

  • Registering snapshots in Awake() before Addressables bank load completes.
  • Proving duck on Windows only while WebGL ships loud combat bed.
  • Skipping gesture gate because Editor autoplay works.
  • Mixing Studio 2.03.0 banks with 2.03.1 integration package.

Troubleshooting

Symptom Fix
Silent entire WebGL build W4 gesture + first-scene help
Music plays, no duck W3 order + W5 audition
Banks missing Addressables strip help
Wwise project instead Different stack—use Wwise DSP help, not this receipt

Mini exercise (50 minutes)

  1. Break W3 on purpose (register in Awake); confirm receipt fails.
  2. Fix load order; pass Windows duck.
  3. Repeat on WebGL build with gesture probe.
  4. Commit receipt; add BUILD_RECEIPT row.
  5. Cross-link from FMOD blog course milestone section.

Continuity

FAQ

Does this replace the FMOD blog?
No—the blog is the playbook; this lesson is the live-ops milestone in your RPG course arc.

Godot + FMOD?
Same W2→W3→W4 order; swap Unity RuntimeManager calls for your engine bridge—receipt schema unchanged.

Help #10 not published yet?
Use WebGL first-scene help until fmod-2-03-bus-snapshot-silent-webgl-after-integration-upgrade-fix ships.

Desktop duck proof is not WebGL duck proof—file fmod_webgl_snapshot_receipt_v1.json before you promote the HTML5 fest branch.