Web Blender Modeler V1 Known Limitations

These limits apply to 0.1.0-rc.1. A successful bounded gate does not imply complete Blender 5.2 parity or support beyond the declared operation, fixture, resource budget and browser configuration. See V1_SCOPE.md and parity-ledger.json for the authoritative capability boundary.

Browser and deployment

Chromium is the only V1 browser baseline. Firefox, WebKit, mobile browsers, touch, pen, IME and non-Chromium accessibility compatibility are not release claims.
Production requires HTTPS. http://127.0.0.1 is allowed for local verification; public plain HTTP and file:// are unsupported. All app, Worker and engine assets must remain same-origin.
The base viewport uses WebGL2. OffscreenCanvas is a second tested production path. WebGPU is used only for the declared bounded NanoVDB path and is subject to adapter availability and limits.

Single-thread and pthread selection

AUTO selects pthread only when crossOriginIsolated, SharedArrayBuffer and Worker capability gates are all ready. Otherwise it selects the single-thread variant and reports the pthread gate.
A pthread initialization failure under AUTO is cleaned up before one single-thread attempt. A resource request failure outside this path remains an error.
A JS, WASM or pthread Worker SHA-256 mismatch is fatal (ENGINE_VARIANT_INTEGRITY_FAILED): there is no integrity fallback and no project is opened.
PTHREAD_REQUIRED blocks when its platform gate is not ready. SINGLE_REQUIRED never attempts pthread. A mixed app/manifest releaseId returns REFRESH_REQUIRED before engine initialization or project open; a full reload is required.
Both variants declare 256 initial WebAssembly pages (16 MiB) and a 32,768-page ceiling (2 GiB). This is a manifest ceiling, not a memory reservation or availability guarantee; Chromium, the OS or the device can reject growth earlier.

Project storage

OPFS and IndexedDB are bound to the exact scheme, host and port. Moving between origins does not migrate projects. Clearing site data or a browser profile deletes locally stored projects and caches.
Chromium and the operating system control quota. V1 reserves no minimum capacity and cannot infer that navigator.storage.estimate() free space will remain available through a save.
Atomic save preserves the last committed revision on quota failure, but the new revision is not durable until save succeeds. Export critical projects before upgrades and before deleting caches.
IndexedDB schema migration is forward-only. OPFS project manifest schema has no general reverse migration. An older app is blocked when it cannot read the current schema.

CPU, WASM and GPU budgets

The RC gates cover 100k, 1M and 10M geometry fixtures; they are not an unlimited scene-size claim. Imports and operations can block earlier when their own vertex, element, transfer, time or memory budgets are exceeded.
A texture asset is limited by protocol to 64 MiB, 16,384 pixels per dimension and 256 requested assets per scene. The actual WebGL MAX_TEXTURE_SIZE, address space and GPU memory may be lower. The release gate exercised 4K and 8K textures, not every format or 16K residency combination.
VDB input is bounded to 512 MiB, a NanoVDB bundle to 1 GiB, each chunk to 16 MiB and declared GPU residency to at most 512 MiB. Actual maxStorageBufferBindingSize and maxBufferSize may be lower.
NanoVDB pages are explicit and LRU-bounded. Automatic viewport page-fault feedback, depth-composed production demand paging and an unbounded multi-grid material system are not included in V1.
GPU device loss or budget failure releases and recreates viewport resources where supported; it does not modify Blender Main or OPFS project bytes. A reduced scene or budget may still be required.

Blender feature scope

Complete PBVH sculpt/paint, arbitrary Geometry Nodes and Shader evaluation, full physics solvers, Cycles, final video encoding, Python/Text autorun, add-ons and native GPU backends are either bounded, server-only or excluded. The exact family slices and stable blockers are in parity-ledger.json; unsupported data must be preserved or explicitly blocked, not reported as executed.

Use DEPLOYMENT.md for installation and rollback requirements, and operations-diagnostics.json for stable failure signals and data-safe recovery boundaries.

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