9 open closure items. Loadable does not mean accepted or performance-valid.

1. P0Define and measure the target performance contract

   The full, budgeted, minimum tiers have no accepted frame target. Record named device/browser/GPU, viewport, DPR, sustained CPU/GPU/presentation p50 and p95, deadline misses, memory, and settled quality. Submission time is not GPU timing.

   tiers[].frameTargetMs
2. P0Native Webgpu capability proof

   The controller awaits WebGPURenderer.init() and rejects any backend where isWebGPUBackend is not true; no fallback is activated.

   capabilityRequirements.native-webgpu
3. P0Renderer Init runtime proof

   Await createTowerShipLabController(), which awaits renderer.init() before exposing labController.

   runtimeProof.renderer-init
4. P0Backend Is Webgpu runtime proof

   Capture getMetrics().nativeWebGPU === true from the initialized controller.

   runtimeProof.backend-is-webgpu
5. P0Mechanism Reachable runtime proof

   Load every physical mechanism route and reconcile the locked path against the selected runtime mode.

   runtimeProof.mechanism-reachable
6. P0Semantic Object Contract runtime proof

   Capture node, socket, collider, destruction-group, and 24-oar inventories from root.userData.sculptRuntime.

   runtimeProof.semantic-object-contract
7. P0Aligned Readback runtime proof

   Capture RGBA8 render-target pixels with the controller-reported integer 256-byte row stride.

   runtimeProof.aligned-readback
8. P1Capture a current-source evidence bundle

   Publish source-hash-bound renderer/backend facts, required diagnostic images, aligned readbacks, resource inventory, timing method, and limitations; directly inspect the important artifacts before promotion.

   evidenceBundle
9. P2Close tier-specific acceptance

   Validate and promote full, budgeted, minimum as independent visual and performance contracts without crossing their protected invariants.

   tiers[].acceptanceStatus