Optional WASM tooling requirements

Status: required, not integrated

These four integrations are required by specification 1.1 but are not installed as working QB Flex capabilities yet. WASM is an optional browser accelerator, not a replacement for server PGlite, server authorization or a native Hermes dependency. Login, CRUD and normal uploads must work without it.

Library	Planned workflow	Required guardrails
SQLite WASM	Inspect explicitly imported databases; local SQL and schema-only rehearsal with synthetic fixtures.	In-memory default; explicit OPFS consent/delete, documented single-owner concurrency; server rehearsal remains authoritative.
jSquash resize/WebP	Opt-in pre-upload optimization with before/after preview.	Preserve original; bound input/pixels/formats; cancellation; server MIME/size/checksum validation remains authoritative.
hash-wasm	Incremental SHA-256 for large browser imports/transfers.	Bounded chunks and workers; optional expected checksum only; native crypto remains the server baseline.
DuckDB-WASM	Local CSV/JSON/Parquet analysis, profiling and bounded result export.	Register local files only; block remote fetching and extension installs; never part of transactional CRUD.

The existing upload SDK already accepts an optional checksum and the server verifies it before S3 persistence; that does not mean the hash-wasm browser worker exists. Current Schema Visualizer is also not a SQLite WASM playground.

Local Data Lab contract

Explicitly imported files stay on the device; nothing uploads automatically. The planned separate workspace includes schema preview, bounded queries, profiling and result export. Default storage is ephemeral; persistence requires consent and an explicit delete control. No management credentials, S3 secrets or master keys enter workers.

Budgets and portability

Allow one active heavy worker per workspace, at most 100 MiB imported files and 2 MiB query results, with a ten-second query/rehearsal timeout. Terminate on cancellation/timeout, bound engine memory where supported and report device/browser limits honestly.

Lazy-load and self-host pinned runtime assets. Review wrapper and embedded-library licenses/advisories. Single-threaded operation is the baseline; do not globally enable isolation headers that break OAuth or embeds. Unsupported devices receive an actionable explanation and working core workflows.

Measure cold startup, download bytes, processing time, memory, cancellation and low-end responsiveness before claiming a performance gain. Acceptance includes malformed/oversized inputs, remote-access rejection, budgets, cancellation, persistence deletion and unchanged core behavior.

Deferred candidates

Tree-sitter requires a justified structural editor and SQLite-compatible grammar. RE2-WASM requires a real user-regex use case and explicit unsupported-syntax rejection. Zstandard needs compression benchmarks, decompressed-size bounds and versioned recovery. ONNX Runtime Web needs justified local models, download budgets and unsupported-device handling. Extism/Wasmtime require certified isolation, capability/resource limits and runtime patching before untrusted functions. These are not installed dependencies or expanded-release promises.