feat(stream)!: decode SSE with the sse-stream crate, aligned with eventsource-parser - #213
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cunninghamcard-bit wants to merge 7 commits into
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The AI SDK's parseJsonEventStream pipes through eventsource-parser. Replace the blank-line frame splitter with its line-based state machine: - \n, \r and \r\n line endings in any mix; a trailing \r waits for a possible \n in the next chunk - strip a UTF-8 BOM at the start of the stream - a field line without ':' has an empty value; empty event -> None; id containing U+0000 ignored; retry accepted only when all ASCII digits - exceeding the buffer limit (event data + partial line) is fatal and ends the stream, as maxBufferSize does upstream Kept from aimux: strict UTF-8 decoding after reassembly (an invalid line now drops only the event being built) and a default 1 MiB bound. extract_lines already matched upstream; the [DONE]-skipping JSON layer in aimux-provider-utils already matches parseJsonEventStream. Co-Authored-By: Claude Opus 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_015EYDYDWYcPsDmjBjFeuDVe
Nothing in the workspace used NdjsonStream / NdjsonError and the AI SDK's provider-utils has no counterpart. Also move tokio to dev-dependencies (only the tests use it), drop the unused direct serde dependency, and update the crate description in README / PROJECT-OVERVIEW. Co-Authored-By: Claude Opus 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_015EYDYDWYcPsDmjBjFeuDVe
A line that failed UTF-8 decoding reset the event, but the lines after it (up to the blank line) were then dispatched as a separate fragment event, producing a second downstream error. Mark the event poisoned until the next blank line so one bad event yields exactly one SseError::Utf8. Also update the aimux-stream description in CONTRIBUTING. Co-Authored-By: Claude Opus 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_015EYDYDWYcPsDmjBjFeuDVe
clippy::collapsible_match rejects the nested `if` under the CI `-D warnings` gate (stable 1.98); behaviour is unchanged. Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
…s suite sse_test.rs was a behaviour list written from scratch, and its header claimed the AI SDK has no SSE parser tests. The parser behind parseJsonEventStream, eventsource-parser, ships its own suite. Port test/parse.test.ts and test/stream.test.ts (v3.1.1, MIT) case for case, driven by the same fixtures; test/multibyte.ts is checked in as JSON and read with include_str!. Cases with no Rust counterpart (onComment counts, reset(), onError payloads) are listed in the file header, as are the adaptations (retry is reported on the event, maxBufferSize maps to with_max_event_size). Four aimux-only tests remain: strict UTF-8, byte-level chunk splitting, transport errors, and the default limit. The four unit tests inside sse.rs are dropped; the port covers them. sha2 (already used by aimux-providers) is a dev-dependency for the upstream SHA-256 check on the 4.8M-character event. The tracker and argument-state tests were already case-for-case ports of the pinned upstream tests; only a comment is added. Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Replace aimux-stream's hand-written SSE parser with a thin adapter over sse-stream 0.3 (WHATWG event-stream parsing), the way the AI SDK's parseJsonEventStream wraps eventsource-parser. The adapter keeps the AI SDK dispatch rules: only blocks with a data line are dispatched, an empty `event:` is None, and `retry` rides on its event. - No event size limit any more, as upstream: `with_max_event_size` and `SseError::FrameTooLarge` are removed. Real recordings of OpenAI Responses and Gemini image generation carry 2-3 MB events; the 1 MiB cap dropped them, and after the previous commit ended the stream on the first one. Both recordings now decode completely (15/15 and 5/5 events). - `SseError::Stream` carries the transport error as its source instead of a String; `Utf8` holds a `str::Utf8Error`; `Decode` covers the rest. Decoder errors end the stream after being reported. - The ported eventsource-parser suite runs unchanged against the adapter (29 cases); the 6 `maxBufferSize` cases go with the limit. - provider-utils: the `SseError::Stream` arm formats the source error. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01WGwanvo9WLU9HWD7sRR8TS
One entry for the final state of the branch: the per-commit changelog hunks described intermediate APIs that no longer exist. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01WGwanvo9WLU9HWD7sRR8TS
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Summary
Split out of #204 (which keeps the tool-call tracker change) so the SSE fixes can be reviewed and merged on their own. Based on
master.aimux-stream'sSseStreamwas a hand-rolled parser with a 1 MiB per-event cap. The AI SDK'sparseJsonEventStreamwrapseventsource-parser; this PR makesSseStreamthe same thing: a thin adapter over thesse-streamcrate (WHATWG event-stream parsing,memchrfeature only).eventsource-parserdoes:\n,\rand\r\nline endings in any mix, a leading UTF-8 BOM is stripped, a field line without:is an empty value, an emptyevent:isNone, anidcontaining U+0000 is ignored,retrymust be all ASCII digits, and a block is dispatched only when it had adataline.with_max_event_sizeandSseError::FrameTooLargeare gone. This fixes the >1 MiB image-generation events recorded from OpenAI Responses and Gemini, which the cap truncated.SseError::Streamcarries the transport error as its source instead of aString;SseError::Utf8holds astr::Utf8Error;SseError::Decodeis added. Decoder errors (invalid UTF-8, transport failure) end the stream after being reported.NdjsonStream/NdjsonErrorare removed (unused, no AI SDK counterpart);tokioandserde_jsonbecome dev-dependencies, the unused directserdedependency is dropped.aimux-provider-utils/src/response_handler.rs, matchesSseError::Streamfor transport errors and turns every other error intoJsonParse.The tracker is untouched here; it is handled in #204.
Type of change
aimux-stream)Notes for reviewers
Tests are ported, not written.
sse_test.rsis a case-for-case port ofeventsource-parserv3.1.1'sparse.test.tsandstream.test.ts(MIT), driven by the same fixtures;test/multibyte.tsis checked in as JSON. What could not be ported (onCommentcounts,reset(),onErrorpayloads, themaxBufferSizecases, which have no counterpart now that there is no cap) is listed in the file header. aimux-only tests: strict UTF-8 as a terminal error, byte-level chunk splitting, transport errors.sha2(already used byaimux-providers) is a dev-dependency for the upstream SHA-256 check.Known, intentional differences from upstream: invalid UTF-8 is a strict, terminal
SseError::Utf8(upstream decodes lossily); Rusttrim()and JStrim()differ onU+FEFF/U+0085, not reachable with real wire data.Commit order: the parser rewrite, NDJSON removal, the UTF-8 error fix, a clippy fix (
collapsible_matchfails the CI-D warningsgate on stable), the test port, the switch tosse-stream, then one CHANGELOG entry describing the final API.Checklist
cargo fmt --all -- --checkcargo clippy -p aimux-stream -p aimux-provider-utils -p aimux-providers --all-targets -- -D warningscargo doc -p aimux-stream -p aimux-provider-utils --no-depswithRUSTDOCFLAGS=-D warningscargo test -p aimux-stream -p aimux-provider-utils -p aimux-providers— the existing chat/completions cassettes exercise the new parser end to end🤖 Generated with Claude Code
https://claude.ai/code/session_01WGwanvo9WLU9HWD7sRR8TS