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[Flight] Add unstable_allowPartialStream option to Flight Client #35731

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Merged
unstubbable merged 2 commits into from
Feb 9, 2026
Merged

[Flight] Add unstable_allowPartialStream option to Flight Client #35731

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2337ad0
[Flight] Add `allowPartialStream` option to Flight Client
unstubbable Feb 6, 2026
f6e060c
Prefix option with `unstable_`
unstubbable Feb 9, 2026
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65 changes: 57 additions & 8 deletions packages/react-client/src/ReactFlightClient.js
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Original file line number Diff line number Diff line change
Expand Up @@ -359,6 +359,7 @@ type Response = {
_stringDecoder: StringDecoder,
_closed: boolean,
_closedReason: mixed,
_allowPartialStream: boolean,
_tempRefs: void | TemporaryReferenceSet, // the set temporary references can be resolved from
_timeOrigin: number, // Profiling-only
_pendingInitialRender: null | TimeoutID, // Profiling-only,
Expand Down Expand Up @@ -1456,9 +1457,19 @@ function getChunk(response: Response, id: number): SomeChunk<any> {
let chunk = chunks.get(id);
if (!chunk) {
if (response._closed) {
// We have already errored the response and we're not going to get
// anything more streaming in so this will immediately error.
chunk = createErrorChunk(response, response._closedReason);
if (response._allowPartialStream) {
// For partial streams, chunks accessed after close should be HALTED
// (never resolve).
chunk = createPendingChunk(response);
const haltedChunk: HaltedChunk<any> = (chunk: any);
haltedChunk.status = HALTED;
haltedChunk.value = null;
haltedChunk.reason = null;
} else {
// We have already errored the response and we're not going to get
// anything more streaming in so this will immediately error.
chunk = createErrorChunk(response, response._closedReason);
}
} else {
chunk = createPendingChunk(response);
}
Expand Down Expand Up @@ -2655,6 +2666,7 @@ function ResponseInstance(
encodeFormAction: void | EncodeFormActionCallback,
nonce: void | string,
temporaryReferences: void | TemporaryReferenceSet,
allowPartialStream: boolean,
findSourceMapURL: void | FindSourceMapURLCallback, // DEV-only
replayConsole: boolean, // DEV-only
environmentName: void | string, // DEV-only
Expand All @@ -2674,6 +2686,7 @@ function ResponseInstance(
this._fromJSON = (null: any);
this._closed = false;
this._closedReason = null;
this._allowPartialStream = allowPartialStream;
this._tempRefs = temporaryReferences;
if (enableProfilerTimer && enableComponentPerformanceTrack) {
this._timeOrigin = 0;
Expand Down Expand Up @@ -2767,6 +2780,7 @@ export function createResponse(
encodeFormAction: void | EncodeFormActionCallback,
nonce: void | string,
temporaryReferences: void | TemporaryReferenceSet,
allowPartialStream: boolean,
findSourceMapURL: void | FindSourceMapURLCallback, // DEV-only
replayConsole: boolean, // DEV-only
environmentName: void | string, // DEV-only
Expand All @@ -2792,6 +2806,7 @@ export function createResponse(
encodeFormAction,
nonce,
temporaryReferences,
allowPartialStream,
findSourceMapURL,
replayConsole,
environmentName,
Expand Down Expand Up @@ -5243,11 +5258,45 @@ function createFromJSONCallback(response: Response) {
}

export function close(weakResponse: WeakResponse): void {
// In case there are any remaining unresolved chunks, they won't
// be resolved now. So we need to issue an error to those.
// Ideally we should be able to early bail out if we kept a
// ref count of pending chunks.
reportGlobalError(weakResponse, new Error('Connection closed.'));
// In case there are any remaining unresolved chunks, they won't be resolved
// now. So we either error or halt them depending on whether partial streams
// are allowed.
// TODO: Ideally we should be able to bail out early if we kept a ref count of
// pending chunks.
if (hasGCedResponse(weakResponse)) {
return;
}
const response = unwrapWeakResponse(weakResponse);
if (response._allowPartialStream) {
// For partial streams, we halt pending chunks instead of erroring them.
response._closed = true;
response._chunks.forEach(chunk => {
if (chunk.status === PENDING) {
// Clear listeners to release closures and transition to HALTED.
// Future .then() calls on HALTED chunks are no-ops.
releasePendingChunk(response, chunk);
const haltedChunk: HaltedChunk<any> = (chunk: any);
haltedChunk.status = HALTED;
haltedChunk.value = null;
haltedChunk.reason = null;
} else if (chunk.status === INITIALIZED && chunk.reason !== null) {
// Stream chunk - close gracefully instead of erroring.
chunk.reason.close('"$undefined"');
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@acdlite acdlite Feb 9, 2026

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This could be an alternative API: pass a special reason exported by React

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@acdlite acdlite Feb 9, 2026

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or similarly, React exports a special AbortController subclass that does this internally

}
});
if (__DEV__) {
const debugChannel = response._debugChannel;
if (debugChannel !== undefined) {
closeDebugChannel(debugChannel);
response._debugChannel = undefined;
if (debugChannelRegistry !== null) {
debugChannelRegistry.unregister(response);
}
}
}
} else {
reportGlobalError(weakResponse, new Error('Connection closed.'));
}
}

function getCurrentOwnerInDEV(): null | ReactComponentInfo {
Expand Down
1 change: 1 addition & 0 deletions packages/react-markup/src/ReactMarkupServer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@ export function experimental_renderToHTML(
noServerCallOrFormAction,
undefined,
undefined,
false,
undefined,
false,
undefined,
Expand Down
1 change: 1 addition & 0 deletions packages/react-noop-renderer/src/ReactNoopFlightClient.js
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,7 @@ function read<T>(source: Source, options: ReadOptions): Thenable<T> {
undefined,
undefined,
undefined,
false,
options !== undefined ? options.findSourceMapURL : undefined,
true,
undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-esm/src/client/ReactFlightDOMClientBrowser.js
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@ export type Options = {
callServer?: CallServerCallback,
debugChannel?: {writable?: WritableStream, readable?: ReadableStream, ...},
temporaryReferences?: TemporaryReferenceSet,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -98,6 +99,9 @@ function createResponseFromOptions(options: void | Options) {
options && options.temporaryReferences
? options.temporaryReferences
: undefined,
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-esm/src/client/ReactFlightDOMClientNode.js
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@ type EncodeFormActionCallback = <A>(
export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -104,6 +105,9 @@ function createFromNodeStream<T>(
options ? options.encodeFormAction : undefined,
options && typeof options.nonce === 'string' ? options.nonce : undefined,
undefined, // TODO: If encodeReply is supported, this should support temporaryReferences
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-parcel/src/client/ReactFlightDOMClientBrowser.js
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,9 @@ function createResponseFromOptions(options: void | Options) {
options && options.temporaryReferences
? options.temporaryReferences
: undefined,
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ ? findSourceMapURL : undefined,
__DEV__ ? (options ? options.replayConsoleLogs !== false : true) : false, // defaults to true
__DEV__ && options && options.environmentName
Expand Down Expand Up @@ -207,6 +210,7 @@ function startReadingFromStream(
export type Options = {
debugChannel?: {writable?: WritableStream, readable?: ReadableStream, ...},
temporaryReferences?: TemporaryReferenceSet,
unstable_allowPartialStream?: boolean,
replayConsoleLogs?: boolean,
environmentName?: string,
startTime?: number,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-parcel/src/client/ReactFlightDOMClientEdge.js
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
temporaryReferences?: TemporaryReferenceSet,
unstable_allowPartialStream?: boolean,
replayConsoleLogs?: boolean,
environmentName?: string,
startTime?: number,
Expand Down Expand Up @@ -104,6 +105,9 @@ function createResponseFromOptions(options?: Options) {
options && options.temporaryReferences
? options.temporaryReferences
: undefined,
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ ? findSourceMapURL : undefined,
__DEV__ && options ? options.replayConsoleLogs === true : false, // defaults to false
__DEV__ && options && options.environmentName
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-parcel/src/client/ReactFlightDOMClientNode.js
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@ type EncodeFormActionCallback = <A>(
export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
unstable_allowPartialStream?: boolean,
replayConsoleLogs?: boolean,
environmentName?: string,
startTime?: number,
Expand Down Expand Up @@ -97,6 +98,9 @@ export function createFromNodeStream<T>(
options ? options.encodeFormAction : undefined,
options && typeof options.nonce === 'string' ? options.nonce : undefined,
undefined, // TODO: If encodeReply is supported, this should support temporaryReferences
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ ? findSourceMapURL : undefined,
__DEV__ && options ? options.replayConsoleLogs === true : false, // defaults to false
__DEV__ && options && options.environmentName
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientBrowser.js
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ export type Options = {
callServer?: CallServerCallback,
debugChannel?: {writable?: WritableStream, readable?: ReadableStream, ...},
temporaryReferences?: TemporaryReferenceSet,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -97,6 +98,9 @@ function createResponseFromOptions(options: void | Options) {
options && options.temporaryReferences
? options.temporaryReferences
: undefined,
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientEdge.js
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,7 @@ export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
temporaryReferences?: TemporaryReferenceSet,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -104,6 +105,9 @@ function createResponseFromOptions(options: Options) {
options && options.temporaryReferences
? options.temporaryReferences
: undefined,
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientNode.js
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ type EncodeFormActionCallback = <A>(
export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -106,6 +107,9 @@ function createFromNodeStream<T>(
options ? options.encodeFormAction : undefined,
options && typeof options.nonce === 'string' ? options.nonce : undefined,
undefined, // TODO: If encodeReply is supported, this should support temporaryReferences
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-unbundled/src/client/ReactFlightDOMClientEdge.js
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,7 @@ export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
temporaryReferences?: TemporaryReferenceSet,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -104,6 +105,9 @@ function createResponseFromOptions(options: Options) {
options && options.temporaryReferences
? options.temporaryReferences
: undefined,
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
4 changes: 4 additions & 0 deletions packages/react-server-dom-unbundled/src/client/ReactFlightDOMClientNode.js
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ type EncodeFormActionCallback = <A>(
export type Options = {
nonce?: string,
encodeFormAction?: EncodeFormActionCallback,
unstable_allowPartialStream?: boolean,
findSourceMapURL?: FindSourceMapURLCallback,
replayConsoleLogs?: boolean,
environmentName?: string,
Expand Down Expand Up @@ -106,6 +107,9 @@ function createFromNodeStream<T>(
options ? options.encodeFormAction : undefined,
options && typeof options.nonce === 'string' ? options.nonce : undefined,
undefined, // TODO: If encodeReply is supported, this should support temporaryReferences
options && options.unstable_allowPartialStream
? options.unstable_allowPartialStream
: false,
__DEV__ && options && options.findSourceMapURL
? options.findSourceMapURL
: undefined,
Expand Down
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