William Dunn
41f0c3d0c6
A design note for SolidCraft in the browser: tiered storage, a SharedWorker job broker, GPU dispatch and in-browser agent control through the same engine commands, with the generic pieces in craft-libs. Linked from the MCP and web getting-started docs.
157 lines
8.6 KiB
Markdown
157 lines
8.6 KiB
Markdown
# Browser runtime (design)
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Design note for SolidCraft in the browser: tiered storage, worker offload, GPU jobs, and
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agent control that stay aligned with the desktop app, the control channel, and
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[MCP](mcp.md). Implementation lives primarily in
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[craft-libs](https://github.com/storytold/craft-libs) (`craft-tier-store`, `craft-worker-host`,
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`craft-gpu`, `craft-runtime`); SolidCraft wires those crates into
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[`apps/solidcraft-web`](../apps/solidcraft-web) and [`files.rs`](../apps/solidcraft-web/src/files.rs)
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rather than growing a second stack here.
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Related: [plugins.md](plugins.md) and [#1221](https://github.com/bherbruck/solidcraft/issues/1221)
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(desktop WIT + wasmtime first; parametric timeline features in phase 2), [design containers](design-container.md),
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[control protocol](control-protocol.md).
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## Problem
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The wasm app today ([`getting-started`](../docs/book/src/guide/getting-started.md)) keeps designs in
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the origin private file system (OPFS) behind virtual `/opfs/` paths, with optional File System
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Access import/export. That works for small and medium designs but hits three walls:
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| Wall | Symptom in SolidCraft |
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|------|------------------------|
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| Quota | Large STEP imports and container blobs compete with autosave and cache in OPFS |
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| Main thread | Open, save, and timeline evaluation run synchronously on the UI thread with egui |
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| Agents | MCP runs out of process (`solidcraft-cli mcp`); the tab has no first-class agent session |
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WebGPU for the viewport already runs on the main thread (wgpu via eframe). Moving the entire UI
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renderer into a worker is out of scope for the first integration; worker GPU is for offload jobs
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(tessellation warm paths, future kernel work), not for egui.
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## Principles
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1. **One command surface.** Toolbar, scripts, control channel, MCP, and (eventually) in-browser
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agents all use the same engine commands. Dialog-free commands only for unattended paths, same
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rule as [MCP](mcp.md).
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2. **Generic traits in craft-libs.** Storage tiers, worker RPC, and GPU dispatch are implemented
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once in craft-libs. Web and native use the same traits; hosts differ (OPFS vs paths, SharedWorker
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vs thread pool).
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3. **Do not duplicate cloud IO.** Authenticated cloud Open/Save uses `craft-cloud` and CollabCraft
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([craft-libs #48](https://github.com/storytold/craft-libs/pull/48)). Browser-local tiers
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(`craft-tier-store`) are separate: hot mirror, warm cache, cold working folder, optional range
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reads of cloud blobs through CollabCraft without vendor types in generic crates.
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4. **One worker broker.** A SharedWorker (or dedicated-worker fallback) coordinates storage writes,
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job queues, and shared wasm module compile per origin. Plugins and offload jobs register on the
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broker; do not spawn one SharedWorker per plugin ([#1221 comment thread](https://github.com/bherbruck/solidcraft/issues/1221)).
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## Architecture
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```text
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Main thread (tab)
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eframe + viewport WebGPU
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hot mirror (sync reads for engine)
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craft_runtime HostFacade ----MessagePort RPC----> SharedWorker broker
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tier-store coordinator (single writer)
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job queue + dedup
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headless engine session(s)
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optional dedicated GPU workers
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ProviderRegistry (GpuJob dispatch)
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Tiers (craft-tier-store)
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Hot RAM mirror, LRU budget
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Warm OPFS under craft/<appId>/… (today: /opfs/ mapping)
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Cold File System Access project folder (no duplicate bytes in OPFS)
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Cloud craft-cloud refs, range fetch via CollabCraft API (not in wasm credentials)
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```
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On **desktop**, the same `BlobStore` and job envelopes apply: warm/cold map to normal directories;
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[`solidcraft-cli mcp`](mcp.md) and wasmtime plugin hosts ([#1221](https://github.com/bherbruck/solidcraft/issues/1221))
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call the same `run(command, args)` JSON.
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## Mapping SolidCraft today
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| Today | Target |
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|-------|--------|
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| [`files.rs`](../apps/solidcraft-web/src/files.rs) OPFS + `/opfs/` VFS | Warm tier keys; migration keeps existing filenames initially |
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| Recovery autosave | Warm tier, same semantics as [`compatibility.md`](compatibility.md) |
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| [Design containers](design-container.md) content-addressed blobs | Tier keys by hash; cold tier holds large blobs without copying into OPFS |
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| [Control protocol](control-protocol.md) over TCP | Same methods over `MessagePort` to broker headless session (WebMCP-shaped, not a second registry) |
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| Parallel mesh work ([ROADMAP](../ROADMAP.md): web path serial) | Offload eval / IO jobs via `JobSubmit`; viewport stays on main thread |
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## craft-libs crates (reference)
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These names follow the craft-libs performance platform design; SolidCraft depends on them as
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published from storytold/craft-libs after cloud contracts land (#48, #52).
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| Crate | Role |
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|-------|------|
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| `craft-tier-store` | `BlobStore`, tier policy, sync mirror over async persist; native + wasm hosts |
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| `craft-worker-host` | SharedWorker bootstrap, RPC messages (`Init`, `StorageOp`, `JobSubmit`, …) |
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| `craft-gpu` | `GpuContext`, `GpuJob`, `GpuProvider`, `ProviderRegistry` (no app WGSL here) |
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| `craft-gpu-wgpu` | wgpu backend: WebGPU on wasm32, Vulkan/DX12/Metal on desktop |
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| `craft-gpu-providers` | Shared readback/composite helpers extracted from Craft app gpu crates |
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| `craft-runtime` | Facade: tier store + worker host + optional `cloud-delegate` hooks |
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Generic runtime code must not depend on SolidCraft crates. SolidCraft registers app-specific
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providers and key namespaces only.
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## GPU and the viewport
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- **Main thread:** eframe owns the WebGPU device used for the 3D view and UI.
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- **Workers:** `craft_runtime::gpu::dispatch(registry, jobs)` runs `GpuJob` lists (chunked buffers,
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readback fences) for offload; same entry point on native thread pools.
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- **Limits:** Capability probe once at init; UI and workers share reported max buffer sizes.
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## Agents in the browser
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| Mode | Transport |
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|------|-----------|
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| Desktop agent | `solidcraft-cli mcp` (stdio) or `--connect` to [control protocol](control-protocol.md) |
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| Browser agent | RPC to broker session; dialog-free tools only |
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| IDE bridge | Optional local relay (stdio MCP ↔ tab); not required for CollabCraft-hosted wasm |
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File policy for web agents mirrors MCP folders: design directory, cold tier roots, recovery;
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never `--allow-any-path` in the tab.
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## Plugins ([#1221](https://github.com/bherbruck/solidcraft/issues/1221))
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| Host | Runtime |
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|------|---------|
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| Desktop | wasmtime + fuel/memory limits; WIT `solidcraft:plugin@1.0.0` with `run`, `manifest`, permissions |
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| Web | Component or module in broker; same WIT contract; sandbox = manifest permissions enforced before `run()` |
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Milestone 1: one-shot commands and importers/exporters. Milestone 2: **parametric timeline
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features** via a generic host-owned `FeatureKind::Plugin` shell (params + display metadata
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including timeline icon and label); plugins rebuild through WIT `evaluate()` calling the same
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`run()` JSON. See [plugins.md](plugins.md). Command ids may use a `pluginname.function` prefix to
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avoid collisions.
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## CollabCraft deployment
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Static wasm apps on `craft.quasarke.net` ship `craft-worker-host.js` (brotli-precompressed) beside
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the app bundle. Prefer one global runtime worker per origin once message routing and wasm size are
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budgeted; per-app worker URLs are acceptable for pilots. CSP must allow `worker-src` / SharedWorker.
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## Phasing (SolidCraft)
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1. **Document and track** (this file); no user-visible change.
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2. **Tier-store wiring:** replace ad-hoc OPFS glue with `craft-tier-store` keys; keep on-disk layout.
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3. **Worker broker:** headless `engine.execute` batches and container IO off UI thread.
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4. **Agent bridge:** MessagePort tool surface equivalent to MCP dialog-free tools.
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5. **Plugins on web:** after desktop wasmtime milestone and WIT stability.
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6. **Parametric plugin features:** [plugins.md](plugins.md) phase 2 (`evaluate`, display metadata, fallback policy).
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## Out of scope (initial integration)
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- Moving egui/viewport WebGPU into SharedWorker
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- Second non-wgpu GPU backend in craft-libs
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- **Implementing** parametric `FeatureKind::Plugin` (designed in [plugins.md](plugins.md); follows craft-runtime wiring)
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- Duplicating `craft-cloud` or embedding `craft-nextcloud` in SolidCraft wasm
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## Tests
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- Extend control-channel scenarios for broker RPC parity where methods map 1:1
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- Worker tests: SharedWorker multi-tab dedup (EffectCraft `workers.mjs` pattern)
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- Tier-store: native LRU tests + wasm OPFS smoke
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- GPU: golden frames remain in app crates; craft-gpu-null for CI dispatch smoke
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