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Fix interleaved reasoning stream formatting #16

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Fix interleaved reasoning stream formatting #16

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382f759
fix interleaved reasoning stream formatting
kenziyuliu Aug 2, 2026
f08c4b1
remove reasoning layout flash
kenziyuliu Aug 2, 2026
13a1f4f
fix active reasoning stream lifecycle
kenziyuliu Aug 2, 2026
f8efdf4
keep thinking live through response stream
kenziyuliu Aug 2, 2026
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70 changes: 52 additions & 18 deletions chat/api.js
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Original file line number Diff line number Diff line change
Expand Up @@ -525,16 +525,35 @@ class OpenRouterAPI {
const REASONING_BUFFER_DELAY = 50; // ms - flush buffer after this delay
const REASONING_BUFFER_SIZE = 20; // chars - flush when buffer reaches this size

// Provider events can alternate between reasoning and visible content. Keep
// their async UI callbacks in wire order so a buffered reasoning delta can
// never be overtaken by the answer delta that follows it.
let callbackQueue = Promise.resolve();
let callbackError = null;
const queueCallback = (callback) => {
callbackQueue = callbackQueue.then(async () => {
if (callbackError) return;
try {
await callback();
} catch (error) {
callbackError = error;
}
});
return callbackQueue;
};

// Helper to flush reasoning buffer
const flushReasoningBuffer = () => {
if (reasoningBuffer && onReasoningChunk) {
onReasoningChunk(reasoningBuffer);
const bufferedReasoning = reasoningBuffer;
reasoningBuffer = '';
queueCallback(() => onReasoningChunk(bufferedReasoning));
}
if (reasoningBufferTimer) {
clearTimeout(reasoningBufferTimer);
reasoningBufferTimer = null;
}
return callbackQueue;
};

// Helper to normalize URLs for deduplication (strip trailing garbage, normalize trailing slashes)
Expand Down Expand Up @@ -770,15 +789,24 @@ class OpenRouterAPI {
}
}

// Check for reasoning in various possible formats
// OpenRouter might send reasoning in different ways
if (parsed.type === 'response.reasoning.delta' ||
parsed.reasoning_delta ||
(parsed.choices?.[0]?.delta?.reasoning)) {

const reasoningContent = parsed.delta ||
parsed.reasoning_delta ||
parsed.choices?.[0]?.delta?.reasoning || '';
const delta = parsed.choices?.[0]?.delta;
const reasoningDetailsContent = Array.isArray(delta?.reasoning_details)
? delta.reasoning_details
.map(detail => {
if (detail?.type === 'reasoning.text') return detail.text || '';
if (detail?.type === 'reasoning.summary') return detail.summary || '';
return '';
})
.join('')
: '';
const directReasoningContent = parsed.type === 'response.reasoning.delta'
? parsed.delta || ''
: parsed.reasoning_delta || delta?.reasoning || '';
const reasoningContent = directReasoningContent || reasoningDetailsContent;

// OpenRouter normalizes provider-specific formats into either a
// direct reasoning delta or text/summary reasoning_details.
if (reasoningContent) {

if (reasoningContent && onReasoningChunk) {
hasReceivedFirstToken = true;
Expand Down Expand Up @@ -835,7 +863,8 @@ class OpenRouterAPI {
if (contentDelta) {
hasReceivedFirstToken = true;
accumulatedContent += contentDelta;
onChunk(contentDelta);
flushReasoningBuffer();
queueCallback(() => onChunk(contentDelta));

// Add reasoning tokens to content tokens for cumulative display
const estimatedContentTokens = Math.ceil(accumulatedContent.length / 4);
Expand All @@ -850,13 +879,13 @@ class OpenRouterAPI {
return;
}

const delta = parsed.choices?.[0]?.delta;
const content = delta?.content;

if (content) {
hasReceivedFirstToken = true;
accumulatedContent += content;
onChunk(content);
flushReasoningBuffer();
queueCallback(() => onChunk(content));

// Add reasoning tokens to content tokens for cumulative display
const estimatedContentTokens = Math.ceil(accumulatedContent.length / 4);
Expand All @@ -872,19 +901,21 @@ class OpenRouterAPI {
// Check for images in the delta (standard OpenRouter format)
if (delta?.images) {
hasReceivedFirstToken = true;
onChunk(null, { images: delta.images });
flushReasoningBuffer();
queueCallback(() => onChunk(null, { images: delta.images }));
}

// Check for image data in reasoning_details (only treat recognised image payloads)
if (delta?.reasoning_details) {
const imageDetails = delta.reasoning_details.filter(detail => this.isReasoningDetailImage(detail));
if (imageDetails.length > 0) {
hasReceivedFirstToken = true;
flushReasoningBuffer();
const images = imageDetails.map(detail => ({
type: 'image_url',
image_url: { url: this.buildImageUrlFromReasoningDetail(detail) }
}));
onChunk(null, { images });
queueCallback(() => onChunk(null, { images }));
}
}

Expand Down Expand Up @@ -922,9 +953,12 @@ class OpenRouterAPI {
}
};

const finalizeStreamResult = () => {
const finalizeStreamResult = async () => {
// Flush any remaining reasoning buffer
flushReasoningBuffer();
await flushReasoningBuffer();
if (callbackError) {
throw callbackError;
}

// Parse citations - prefer annotations over content parsing
if (searchEnabled) {
Expand Down Expand Up @@ -1140,7 +1174,7 @@ class OpenRouterAPI {
return finalizeStreamResult();
} catch (error) {
// Flush any remaining reasoning buffer before handling error
flushReasoningBuffer();
await flushReasoningBuffer();

let streamError = error;
if (!(streamError instanceof Error)) {
Expand Down
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