[1egoman]

Fixes review findings against #1166 in the Dart layer around the Rust core. One commit per fix, each with a regression test that fails without it.

Warning

Not mergeable as-is. The last commit needs OutgoingPacketBatch from livekit-ffi, which isn't released yet. Until then, pubspec.yaml and example/pubspec.yaml carry a TEMPORARY dependency_overrides pointing at a local rust-sdks worktree, so CI won't build this branch. Once the rust-sdks change below is released, replace the override with a livekit_ffi version bump.

Fixes

• Bump livekit_ffi to 0.13.3: exports StreamReader.close() and merges trailer attributes into the reader's info.
• Trailer attributes dropped on native: the handler got the info captured when the stream opened, so header{a:1} + chunk + trailer{b:2} gave {a:1}. The info is now re-read from the core when the stream ends and its attributes merged in, as the web path does.
• MIME type not inferred for sendFile and sendText attachments: the core does no inference and falls back to application/octet-stream. This restores main's options.mimeType ?? mime(basename(path)) on native and web.
• Cancelling a subscription didn't end the stream: onCancel only set a flag, so the core kept the stream open and kept buffering until the sender sent again. It now calls the reader's close(), which returns immediately and wakes the pump. The pump still owns dispose(), so there's no use-after-free.
• No data channel backpressure on native sends: the pump now waits for the buffer status to be low before each packet, as WritableStream did on main. It also sends a whole batch before pulling the next one, which replaces the separate send chain.
• Send results didn't reflect delivery: sendText/sendBytes/write resolved once packets were buffered in Rust, and transport errors were only logged, so await sendText(); await room.disconnect(); could silently drop the message. The pump now settles each batch: it completes the batch once its packets are through the engine, or fails it with the error, which the core surfaces to the send as SendFailed. Because the core holds the send until then, this also stops sendFile from reading the whole file into Rust memory.

Depends on

A rust-sdks change, branch ffi/polled-outgoing-delivery-ack, not yet pushed. OutgoingPacketQueue::on_packets_available used to acknowledge as soon as packets were buffered, which breaks the delegate's contract (return only once the packets are on the transport). next_packets() now returns an OutgoingPacketBatch that the host completes or fails. Closing the queue, or dropping a batch without settling it, fails the waiting send. At most one batch is outstanding.

Not addressed

• TextStreamInfo.operationType/version are no longer null on native, because the core reports defaults (create/0) where main and web report null. Left as is pending a decision.
• Web reset() closes readers without an error. Intentionally deferred.

Testing

• flutter test: all 518 pass, run against the overridden livekit_ffi.
• cargo test -p livekit-ffi --no-default-features --features core-modules data_stream: all 27 pass. Clippy is clean.

🤖 Generated with Claude Code