[tmm]

Part of the Rust parity push: two JS options the Rust client lacked.

Releases as zero-rust 0.2.0 (minor changeset): adding public fields to ZeroOptions breaks a struct literal that names every field (constructible_struct_adds_field). ZeroOptions stays a plain struct; later new options are minor bumps too.

getTraceparent. JS puts a W3C traceparent on every changeDesiredQueries, initConnection message, and push it sends. Rust and Swift hard-coded none.

• ZeroOptions::get_traceparent in Rust and ZeroOptions.getTraceparent in Swift fill it in the places JS does.
• The Sec-WebSocket-Protocol header stays without one, as in JS.

batchViewUpdates. JS wraps each update of the views in it: a new view's creation, and each change (poke, mutation, first hydration) together with its listener calls. That lets a UI render one batch at once.

• ZeroOptions::batch_view_updates does the same in Rust. A callback that doesn't call the function it's given panics with JS's assertion message.
• Swift's QueryContext already took this internally; ZeroOptions.batchViewUpdates exposes it.

Ttl::DEFAULT_PRELOAD. JS's preload default is none (0 ms). Ttl::default() is the 5 minutes that views and run use, so passing it to a preload would keep the query synced 5 minutes longer than JS does.

rust/PARITY.md.

• Lists the options still not ported: slowMaterializeThreshold, and the deprecated maxRecentQueries.
• Maps the deprecated aliases (server, getQueriesURL, onOnlineChange).
• Explains the two defaults that differ from JS: memory storage, and no delay before a hidden app disconnects.

Vectors. Three new JS client scenarios, through traceparent and batchViewUpdates scenario options in harness.ts:

• connection.ts: traceparents on query changes before and after connecting, and on a push.
• connection.ts: a traceparent on an initConnection too large for the header.
• pokes.ts: each batch that wrapped listener calls, with how many: one per poke and per mutation, across every view. How often JS calls the callback with nothing to update (while hydrating) isn't recorded.

Without the Rust changes, these scenarios fail in Rust. Removing the batch around a change fails the batching scenario on memory and on SQLite.

Checks.

• Rust conformance: client.json 187/187, memory and SQLite.
• Swift: swift test --filter ClientConformanceTests and swift format lint --strict pass.
• Rust: cargo test --workspace, clippy -D warnings, and cargo doc -D warnings pass.
• Benchmarks: pokes, mutations, and first sync against main in turns, in both orders, are within ±4% noise.