From 43e9d36bb91522fbcddd66bd61d89b2d65fa5ac2 Mon Sep 17 00:00:00 2001
From: Haroen Viaene <hello@haroen.me>
Date: Tue, 31 Mar 2026 10:21:33 +0200
Subject: [PATCH 01/23] WIP: streaming tools

---
 examples/react/getting-started/src/App.tsx    | 213 ++++++++++++++++++
 .../src/components/chat/types.ts              |   2 +
 .../chat/__tests__/connectChat-test.ts        |  59 +++++
 .../src/lib/ai-lite/abstract-chat.ts          | 156 ++++++++++++-
 .../instantsearch.js/src/lib/ai-lite/types.ts |   2 +
 .../widgets/chat/tools/SearchIndexTool.tsx    |  37 +++
 6 files changed, 467 insertions(+), 2 deletions(-)

diff --git a/examples/react/getting-started/src/App.tsx b/examples/react/getting-started/src/App.tsx
index cef7ca85bc4..706e3b8a249 100644
--- a/examples/react/getting-started/src/App.tsx
+++ b/examples/react/getting-started/src/App.tsx
@@ -27,6 +27,216 @@ const searchClient = algoliasearch(
   '6be0576ff61c053d5f9a3225e2a90f76'
 );
 
+const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
+const TOOL_OUTPUT_STEP_DELAY_MS = 900;
+
+const normalizeToolOutputEvent = (event: any): any => {
+  if (event?.type !== 'tool-output-available' || !event.output) {
+    return event;
+  }
+
+  const output = event.output as Record<string, any>;
+
+  if (Array.isArray(output.hits)) {
+    return event;
+  }
+
+  if (
+    Array.isArray(output.results) &&
+    output.results.length > 0 &&
+    Array.isArray(output.results[0]?.hits)
+  ) {
+    const hits = output.results[0].hits;
+    return {
+      ...event,
+      output: {
+        ...output,
+        hits,
+        nbHits: output.nbHits ?? hits.length,
+      },
+    };
+  }
+
+  return event;
+};
+
+const getProgressiveToolOutputEvents = (event: any): any[] => {
+  if (event?.type !== 'tool-output-available' || !event.output) {
+    return [];
+  }
+
+  const output = event.output as Record<string, any>;
+
+  if (Array.isArray(output.hits) && output.hits.length > 1) {
+    return output.hits.slice(0, -1).map((_: any, index: number) => ({
+      ...event,
+      preliminary: true,
+      output: {
+        ...output,
+        hits: output.hits.slice(0, index + 1),
+      },
+    }));
+  }
+
+  if (Array.isArray(output.results) && output.results.length > 0) {
+    const firstResultWithHitsIndex = output.results.findIndex(
+      (result: any) => Array.isArray(result?.hits) && result.hits.length > 1
+    );
+
+    if (firstResultWithHitsIndex === -1) {
+      return [];
+    }
+
+    const hits = output.results[firstResultWithHitsIndex].hits;
+    return hits.slice(0, -1).map((_: any, index: number) => ({
+      ...event,
+      preliminary: true,
+      output: {
+        ...output,
+        results: output.results.map((result: any, resultIndex: number) =>
+          resultIndex === firstResultWithHitsIndex
+            ? {
+                ...result,
+                hits: hits.slice(0, index + 1),
+              }
+            : result
+        ),
+      },
+    }));
+  }
+
+  return [];
+};
+
+const delayedChatFetch: typeof fetch = async (input, init) => {
+  const response = await fetch(input, init);
+
+  const isEventStream =
+    response.headers.get('content-type')?.includes('text/event-stream') ??
+    false;
+
+  if (!response.body || !isEventStream) {
+    return response;
+  }
+
+  const reader = response.body.getReader();
+  const decoder = new TextDecoder();
+  const encoder = new TextEncoder();
+  let hasInjectedOutputDelay = false;
+  let pendingText = '';
+
+  const delayedBody = new ReadableStream<Uint8Array>({
+    async start(controller) {
+      const emitLine = async (line: string): Promise<void> => {
+        if (!line.startsWith('data: ')) {
+          controller.enqueue(encoder.encode(line));
+          return;
+        }
+
+        const payload = line.slice(6).trim();
+        if (payload === '[DONE]') {
+          controller.enqueue(encoder.encode(line));
+          return;
+        }
+
+        let parsedEvent: any;
+        try {
+          parsedEvent = JSON.parse(payload);
+        } catch {
+          controller.enqueue(encoder.encode(line));
+          return;
+        }
+
+        if (
+          !hasInjectedOutputDelay &&
+          parsedEvent?.type === 'tool-output-available'
+        ) {
+          const normalizedToolOutputEvent =
+            normalizeToolOutputEvent(parsedEvent);
+          const progressiveEvents = getProgressiveToolOutputEvents(
+            normalizedToolOutputEvent
+          );
+
+          if (progressiveEvents.length > 0) {
+            hasInjectedOutputDelay = true;
+
+            const emitProgressiveOutput = (index: number): Promise<void> => {
+              if (index >= progressiveEvents.length) {
+                controller.enqueue(
+                  encoder.encode(
+                    `data: ${JSON.stringify(normalizedToolOutputEvent)}\n`
+                  )
+                );
+                controller.enqueue(encoder.encode('\n'));
+                return Promise.resolve();
+              }
+
+              controller.enqueue(
+                encoder.encode(
+                  `data: ${JSON.stringify(progressiveEvents[index])}\n`
+                )
+              );
+              controller.enqueue(encoder.encode('\n'));
+
+              return sleep(TOOL_OUTPUT_STEP_DELAY_MS).then(() =>
+                emitProgressiveOutput(index + 1)
+              );
+            };
+
+            return emitProgressiveOutput(0);
+          }
+        }
+
+        controller.enqueue(encoder.encode(line));
+      };
+
+      const processPendingLines = (): Promise<void> => {
+        const lineBreakIndex = pendingText.indexOf('\n');
+        if (lineBreakIndex === -1) {
+          return Promise.resolve();
+        }
+
+        const line = pendingText.slice(0, lineBreakIndex + 1);
+        pendingText = pendingText.slice(lineBreakIndex + 1);
+
+        return emitLine(line).then(() => processPendingLines());
+      };
+
+      const pump = (): Promise<void> =>
+        reader.read().then(({ done, value }) => {
+          if (done) {
+            if (pendingText) {
+              controller.enqueue(encoder.encode(pendingText));
+            }
+            controller.close();
+            return Promise.resolve();
+          }
+
+          if (!value) {
+            return pump();
+          }
+
+          pendingText += decoder.decode(value, { stream: true });
+          return processPendingLines().then(() => pump());
+        });
+
+      try {
+        await pump();
+      } catch (error) {
+        controller.error(error);
+      } finally {
+        reader.releaseLock();
+      }
+    },
+  });
+
+  return new Response(delayedBody, {
+    status: response.status,
+    statusText: response.statusText,
+    headers: response.headers,
+  });
+};
+
 export function App() {
   return (
     <div>
@@ -94,6 +304,9 @@ export function App() {
           <Chat
             agentId="eedef238-5468-470d-bc37-f99fa741bd25"
             itemComponent={ItemComponent}
+            transport={{
+              fetch: delayedChatFetch,
+            }}
           />
         </InstantSearch>
       </div>
diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index e1c22139831..558aabf4f31 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -121,6 +121,7 @@ export type ToolUIPart<TTools extends UITools = UITools> = ValueOf<{
     | {
         state: 'input-streaming';
         input: DeepPartial<TTools[NAME]['input']> | undefined;
+        rawInput?: string;
         providerExecuted?: boolean;
         output?: never;
         errorText?: never;
@@ -165,6 +166,7 @@ export type DynamicToolUIPart = {
   | {
       state: 'input-streaming';
       input: unknown | undefined;
+      rawInput?: string;
       output?: never;
       errorText?: never;
     }
diff --git a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
index 6aaa828df54..4b96c248648 100644
--- a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
+++ b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
@@ -443,6 +443,65 @@ data: [DONE]`,
         );
       });
     });
+
+    it('streams tool input parts from tool-input-delta without tool-input-available', async () => {
+      const { widget } = getInitializedWidget({
+        agentId: undefined,
+        transport: {
+          fetch: () =>
+            Promise.resolve(
+              new Response(
+                `data: {"type": "start", "messageId": "test-id"}
+
+data: {"type": "start-step"}
+
+data: {"type": "tool-input-start", "toolCallId": "call_1", "toolName": "displayResults"}
+
+data: {"type": "tool-input-delta", "toolCallId": "call_1", "toolName": "displayResults", "inputDelta": "{}"}
+
+data: {"type": "finish-step"}
+
+data: {"type": "finish"}
+
+data: [DONE]`,
+                {
+                  headers: { 'Content-Type': 'text/event-stream' },
+                }
+              )
+            ),
+        },
+      });
+
+      const { chatInstance } = widget;
+
+      await chatInstance.sendMessage({
+        id: 'message-id',
+        role: 'user',
+        parts: [{ type: 'text', text: 'Show me product groups' }],
+      });
+
+      await waitFor(() => {
+        const lastMessage = chatInstance.messages[chatInstance.messages.length - 1];
+        expect(lastMessage?.role).toBe('assistant');
+
+        const toolPart = lastMessage?.parts.find(
+          (part) =>
+            'type' in part &&
+            part.type === 'tool-displayResults' &&
+            'toolCallId' in part &&
+            part.toolCallId === 'call_1'
+        ) as
+          | {
+              state: string;
+              rawInput?: string;
+              input?: Record<string, unknown>;
+            }
+          | undefined;
+
+        expect(toolPart?.state).toBe('input-streaming');
+        expect(toolPart?.input).toEqual({});
+      });
+    });
   });
 
   describe('transport configuration', () => {
diff --git a/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts b/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
index d31307101e2..fda337b2700 100644
--- a/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
+++ b/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
@@ -26,6 +26,96 @@ type ActiveResponse = {
   stream?: ReadableStream<UIMessageChunk>;
 };
 
+const tryParseJson = (value: string): unknown | undefined => {
+  try {
+    return JSON.parse(value);
+  } catch {
+    return undefined;
+  }
+};
+
+const repairPartialJson = (value: string): string => {
+  let repaired = value.trim();
+
+  if (!repaired) {
+    return repaired;
+  }
+
+  let inString = false;
+  let isEscaped = false;
+  const stack: Array<'{' | '['> = [];
+
+  for (let index = 0; index < repaired.length; index++) {
+    const char = repaired[index];
+    if (inString) {
+      if (isEscaped) {
+        isEscaped = false;
+      } else if (char === '\\') {
+        isEscaped = true;
+      } else if (char === '"') {
+        inString = false;
+      }
+      continue;
+    }
+
+    if (char === '"') {
+      inString = true;
+      continue;
+    }
+
+    if (char === '{' || char === '[') {
+      stack.push(char);
+      continue;
+    }
+
+    if (char === '}' && stack[stack.length - 1] === '{') {
+      stack.pop();
+      continue;
+    }
+
+    if (char === ']' && stack[stack.length - 1] === '[') {
+      stack.pop();
+    }
+  }
+
+  if (inString && !isEscaped) {
+    repaired += '"';
+  }
+
+  repaired = repaired.replace(/,\s*$/u, '');
+
+  if (stack.length > 0) {
+    repaired += stack
+      .reverse()
+      .map((opening) => (opening === '{' ? '}' : ']'))
+      .join('');
+  }
+
+  return repaired.replace(/,\s*([}\]])/gu, '$1');
+};
+
+const parseToolInputDelta = (
+  accumulatedRawInput: string,
+  fallbackInput: unknown
+): unknown => {
+  const normalized = accumulatedRawInput.trim();
+  if (!normalized) {
+    return fallbackInput;
+  }
+
+  const directParsed = tryParseJson(normalized);
+  if (directParsed !== undefined) {
+    return directParsed;
+  }
+
+  const repairedParsed = tryParseJson(repairPartialJson(normalized));
+  if (repairedParsed !== undefined) {
+    return repairedParsed;
+  }
+
+  return fallbackInput;
+};
+
 /**
  * Abstract base class for chat implementations.
  */
@@ -437,6 +527,7 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
     // Track current text/reasoning part state
     let currentTextPartId: string | undefined;
     let currentReasoningPartId: string | undefined;
+    const toolRawInputByCallId: Record<string, string> = {};
 
     // Promise chain for handling tool calls that return promises
     let pendingToolCall: Promise<void> = Promise.resolve();
@@ -623,11 +714,21 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
             case 'tool-input-start': {
               if (!currentMessage) break;
 
+              const initialRawInput =
+                typeof chunk.input === 'string'
+                  ? chunk.input
+                  : chunk.input !== undefined
+                  ? JSON.stringify(chunk.input)
+                  : '';
+
+              toolRawInputByCallId[chunk.toolCallId] = initialRawInput;
+
               const toolPart = {
                 type: `tool-${chunk.toolName}` as const,
                 toolCallId: chunk.toolCallId,
                 state: 'input-streaming' as const,
                 input: chunk.input,
+                rawInput: initialRawInput || undefined,
                 providerExecuted: chunk.providerExecuted,
               };
 
@@ -640,14 +741,61 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
             }
 
             case 'tool-input-delta': {
-              // Tool input streaming - we'd need to parse partial JSON
-              // For now, we'll wait for tool-input-available
+              if (!currentMessage) break;
+
+              const toolIndex = currentMessage.parts.findIndex(
+                (p) => 'toolCallId' in p && p.toolCallId === chunk.toolCallId
+              );
+
+              const existingPart =
+                toolIndex >= 0
+                  ? (currentMessage.parts[toolIndex] as any)
+                  : null;
+              const previousRawInput =
+                existingPart?.rawInput ??
+                toolRawInputByCallId[chunk.toolCallId] ??
+                '';
+              const nextRawInput = `${previousRawInput}${chunk.inputDelta}`;
+              toolRawInputByCallId[chunk.toolCallId] = nextRawInput;
+
+              const parsedInput = parseToolInputDelta(
+                nextRawInput,
+                existingPart?.input
+              );
+
+              const nextToolPart = {
+                ...(existingPart ?? {
+                  type: `tool-${chunk.toolName}` as const,
+                  toolCallId: chunk.toolCallId,
+                }),
+                state: 'input-streaming' as const,
+                input: parsedInput,
+                rawInput: nextRawInput,
+              };
+
+              if (toolIndex >= 0) {
+                const updatedParts = [...currentMessage.parts];
+                updatedParts[toolIndex] = nextToolPart;
+                currentMessage = {
+                  ...currentMessage,
+                  parts: updatedParts,
+                } as TUIMessage;
+              } else {
+                currentMessage = {
+                  ...currentMessage,
+                  parts: [...currentMessage.parts, nextToolPart],
+                } as TUIMessage;
+              }
+
+              this.state.replaceMessage(currentMessageIndex, currentMessage);
               break;
             }
 
             case 'tool-input-available': {
               if (!currentMessage) break;
 
+              delete toolRawInputByCallId[chunk.toolCallId];
+
               // Find existing tool part or create new one
               const existingIndex = currentMessage.parts.findIndex(
                 (p) => 'toolCallId' in p && p.toolCallId === chunk.toolCallId
@@ -702,6 +850,8 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
               );
 
               if (toolIndex >= 0) {
+                delete toolRawInputByCallId[chunk.toolCallId];
+
                 const updatedParts = [...currentMessage.parts];
                 const existingPart = updatedParts[toolIndex] as any;
                 updatedParts[toolIndex] = {
@@ -728,6 +878,8 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
               );
 
               if (toolIndex >= 0) {
+                delete toolRawInputByCallId[chunk.toolCallId];
+
                 const updatedParts = [...currentMessage.parts];
                 const existingPart = updatedParts[toolIndex] as any;
                 updatedParts[toolIndex] = {
diff --git a/packages/instantsearch.js/src/lib/ai-lite/types.ts b/packages/instantsearch.js/src/lib/ai-lite/types.ts
index a317953ae42..fdbe9f3825a 100644
--- a/packages/instantsearch.js/src/lib/ai-lite/types.ts
+++ b/packages/instantsearch.js/src/lib/ai-lite/types.ts
@@ -84,6 +84,7 @@ export type ToolUIPart<TOOLS extends UITools = UITools> = ValueOf<{
     | {
         state: 'input-streaming';
         input: DeepPartial<TOOLS[NAME]['input']> | undefined;
+        rawInput?: string;
         providerExecuted?: boolean;
         output?: never;
         errorText?: never;
@@ -125,6 +126,7 @@ export type DynamicToolUIPart = {
   | {
       state: 'input-streaming';
       input: unknown | undefined;
+      rawInput?: string;
       output?: never;
       errorText?: never;
     }
diff --git a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
index 0aebcd66d59..9e14e24cd45 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
@@ -44,6 +44,7 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
       | {
           query: string;
           number_of_results?: number;
+          facet_filters?: string[][];
         }
       | undefined;
 
@@ -56,6 +57,42 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
 
     const items = output?.hits || [];
 
+    const appliedStreamingInputRef = React.useRef<string>('');
+
+    React.useEffect(() => {
+      if (
+        message?.state !== 'input-streaming' &&
+        message?.state !== 'input-available'
+      ) {
+        return;
+      }
+
+      if (!input) {
+        return;
+      }
+
+      const hasQuery = input.query.trim().length > 0;
+      const hasFacetFilters = (input.facet_filters?.length ?? 0) > 0;
+      if (!hasQuery && !hasFacetFilters) {
+        return;
+      }
+
+      const inputSignature = JSON.stringify({
+        query: input.query,
+        facet_filters: input.facet_filters,
+      });
+
+      if (appliedStreamingInputRef.current === inputSignature) {
+        return;
+      }
+
+      appliedStreamingInputRef.current = inputSignature;
+      applyFilters({
+        query: input.query,
+        facetFilters: input.facet_filters,
+      });
+    }, [applyFilters, input, message?.state]);
+
     const MemoedHeaderComponent = React.useMemo(() => {
       return (
         props: Omit<

From 8355da7dd1bd9a98d8ba238756204aa4cc44d784 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Thu, 2 Apr 2026 10:24:13 +0100
Subject: [PATCH 02/23] fix delta key

---
 .../src/components/chat/ChatMessages.tsx      |  3 +-
 .../src/lib/utils/chat.ts                     |  8 +++++
 .../chat/__tests__/connectChat-test.ts        |  2 +-
 .../src/lib/ai-lite/abstract-chat.ts          |  2 +-
 .../instantsearch.js/src/lib/ai-lite/types.ts |  2 +-
 .../widgets/chat/tools/SearchIndexTool.tsx    | 36 -------------------
 6 files changed, 13 insertions(+), 40 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 873e3839f45..3bdb4b937a8 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -5,6 +5,7 @@ import {
   getTextContent,
   hasTextContent,
   isPartText,
+  isPartTool,
 } from '../../lib/utils/chat';
 import { createButtonComponent } from '../Button';
 
@@ -328,7 +329,7 @@ export function createChatMessagesComponent({
     const isWaitingForResponse = status === 'submitted';
     const isStreamingWithNoContent = status === 'streaming' && !lastPart;
     const isStreamingNonTextContent =
-      status === 'streaming' && lastPart && !isPartText(lastPart);
+      status === 'streaming' && lastPart && !(isPartText(lastPart) || isPartTool(lastPart));
 
     const showLoader =
       isWaitingForResponse ||
diff --git a/packages/instantsearch-ui-components/src/lib/utils/chat.ts b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
index 0e170dd5009..64ef730d57d 100644
--- a/packages/instantsearch-ui-components/src/lib/utils/chat.ts
+++ b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
@@ -1,3 +1,5 @@
+import { startsWith } from './startsWith';
+
 import type { ChatMessageBase } from '../../components';
 
 export const getTextContent = (message: ChatMessageBase) => {
@@ -15,3 +17,9 @@ export const isPartText = (
 ): part is Extract<ChatMessageBase['parts'][number], { type: 'text' }> => {
   return part.type === 'text';
 };
+
+export const isPartTool = (
+  part: ChatMessageBase['parts'][number]
+): part is Extract<ChatMessageBase['parts'][number], { type: 'tool' }> => {
+  return startsWith(part.type, 'tool-');
+};
diff --git a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
index 4b96c248648..7e9ff485613 100644
--- a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
+++ b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
@@ -457,7 +457,7 @@ data: {"type": "start-step"}
 
 data: {"type": "tool-input-start", "toolCallId": "call_1", "toolName": "displayResults"}
 
-data: {"type": "tool-input-delta", "toolCallId": "call_1", "toolName": "displayResults", "inputDelta": "{}"}
+data: {"type": "tool-input-delta", "toolCallId": "call_1", "toolName": "displayResults", "inputTextDelta": "{}"}
 
 data: {"type": "finish-step"}
 
diff --git a/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts b/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
index fda337b2700..ff0dd4db310 100644
--- a/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
+++ b/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
@@ -755,7 +755,7 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
                 existingPart?.rawInput ??
                 toolRawInputByCallId[chunk.toolCallId] ??
                 '';
-              const nextRawInput = `${previousRawInput}${chunk.inputDelta}`;
+              const nextRawInput = `${previousRawInput}${chunk.inputTextDelta}`;
               toolRawInputByCallId[chunk.toolCallId] = nextRawInput;
 
               const parsedInput = parseToolInputDelta(
diff --git a/packages/instantsearch.js/src/lib/ai-lite/types.ts b/packages/instantsearch.js/src/lib/ai-lite/types.ts
index fdbe9f3825a..daf60dc86be 100644
--- a/packages/instantsearch.js/src/lib/ai-lite/types.ts
+++ b/packages/instantsearch.js/src/lib/ai-lite/types.ts
@@ -269,7 +269,7 @@ export type UIMessageChunk<
       type: 'tool-input-delta';
       toolName: string;
       toolCallId: string;
-      inputDelta: string;
+      inputTextDelta: string;
     }
   | {
       type: 'tool-output-available';
diff --git a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
index 9e14e24cd45..33bfd686404 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
@@ -57,42 +57,6 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
 
     const items = output?.hits || [];
 
-    const appliedStreamingInputRef = React.useRef<string>('');
-
-    React.useEffect(() => {
-      if (
-        message?.state !== 'input-streaming' &&
-        message?.state !== 'input-available'
-      ) {
-        return;
-      }
-
-      if (!input) {
-        return;
-      }
-
-      const hasQuery = input.query.trim().length > 0;
-      const hasFacetFilters = (input.facet_filters?.length ?? 0) > 0;
-      if (!hasQuery && !hasFacetFilters) {
-        return;
-      }
-
-      const inputSignature = JSON.stringify({
-        query: input.query,
-        facet_filters: input.facet_filters,
-      });
-
-      if (appliedStreamingInputRef.current === inputSignature) {
-        return;
-      }
-
-      appliedStreamingInputRef.current = inputSignature;
-      applyFilters({
-        query: input.query,
-        facetFilters: input.facet_filters,
-      });
-    }, [applyFilters, input, message?.state]);
-
     const MemoedHeaderComponent = React.useMemo(() => {
       return (
         props: Omit<

From 929f2c08f1441fe0f845e8d1233f175758c34e0c Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Thu, 2 Apr 2026 14:39:18 +0100
Subject: [PATCH 03/23] fix loader

---
 .../src/components/chat/ChatMessages.tsx           |  4 ++--
 .../src/lib/utils/chat.ts                          | 14 +++++++++++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 3bdb4b937a8..2dc307a3860 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -5,7 +5,7 @@ import {
   getTextContent,
   hasTextContent,
   isPartText,
-  isPartTool,
+  isToolPartActivelyRendering,
 } from '../../lib/utils/chat';
 import { createButtonComponent } from '../Button';
 
@@ -329,7 +329,7 @@ export function createChatMessagesComponent({
     const isWaitingForResponse = status === 'submitted';
     const isStreamingWithNoContent = status === 'streaming' && !lastPart;
     const isStreamingNonTextContent =
-      status === 'streaming' && lastPart && !(isPartText(lastPart) || isPartTool(lastPart));
+      status === 'streaming' && lastPart && !(isPartText(lastPart) || isToolPartActivelyRendering(lastPart));
 
     const showLoader =
       isWaitingForResponse ||
diff --git a/packages/instantsearch-ui-components/src/lib/utils/chat.ts b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
index 64ef730d57d..55da19f4294 100644
--- a/packages/instantsearch-ui-components/src/lib/utils/chat.ts
+++ b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
@@ -1,6 +1,7 @@
 import { startsWith } from './startsWith';
 
 import type { ChatMessageBase } from '../../components';
+import type { ChatToolMessage } from '../../components/chat/types';
 
 export const getTextContent = (message: ChatMessageBase) => {
   return message.parts
@@ -20,6 +21,17 @@ export const isPartText = (
 
 export const isPartTool = (
   part: ChatMessageBase['parts'][number]
-): part is Extract<ChatMessageBase['parts'][number], { type: 'tool' }> => {
+): part is ChatToolMessage => {
   return startsWith(part.type, 'tool-');
 };
+
+export const isToolPartActivelyRendering = (
+  part: ChatMessageBase['parts'][number]
+): boolean => {
+  return (
+    isPartTool(part) &&
+    (part.state === 'input-streaming' ||
+      part.state === 'output-available' ||
+      part.state === 'output-error')
+  );
+};

From 80c4486d4a56371c021192ec9622dfde63cab10b Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Thu, 2 Apr 2026 14:39:29 +0100
Subject: [PATCH 04/23] update tests

---
 tests/common/widgets/chat/options.tsx | 53 +++++++++++++++++++++++++--
 1 file changed, 50 insertions(+), 3 deletions(-)

diff --git a/tests/common/widgets/chat/options.tsx b/tests/common/widgets/chat/options.tsx
index 123a2bacaea..978c495e131 100644
--- a/tests/common/widgets/chat/options.tsx
+++ b/tests/common/widgets/chat/options.tsx
@@ -380,7 +380,7 @@ export function createOptionsTests(
         ).toBeInTheDocument();
       });
 
-      test('shows loader during streaming when last part is a tool without output', async () => {
+      test('does not show loader during streaming when last part is a tool with streaming input', async () => {
         const searchClient = createSearchClient();
         const chat = new Chat({});
 
@@ -422,12 +422,59 @@ export function createOptionsTests(
           await wait(0);
         });
 
+        expect(
+          document.querySelector('.ais-ChatMessageLoader')
+        ).not.toBeInTheDocument();
+      });
+
+      test('shows loader during streaming when last part is a tool with input available', async () => {
+        const searchClient = createSearchClient();
+        const chat = new Chat({});
+
+        await setup({
+          instantSearchOptions: {
+            indexName: 'indexName',
+            searchClient,
+          },
+          widgetParams: {
+            javascript: createDefaultWidgetParams(chat),
+            react: createDefaultWidgetParams(chat),
+            vue: {},
+          },
+        });
+
+        await openChat(act);
+
+        await act(async () => {
+          chat._state.messages = [
+            {
+              id: '1',
+              role: 'user',
+              parts: [{ type: 'text', text: 'Hello' }],
+            },
+            {
+              id: '2',
+              role: 'assistant',
+              parts: [
+                {
+                  type: `tool-${SearchIndexToolType}`,
+                  toolCallId: '1',
+                  state: 'input-available',
+                  input: { query: 'shoes' },
+                },
+              ],
+            },
+          ] as any;
+          chat._state.status = 'streaming';
+          await wait(0);
+        });
+
         expect(
           document.querySelector('.ais-ChatMessageLoader')
         ).toBeInTheDocument();
       });
 
-      test('shows loader during streaming when last part is a tool with output', async () => {
+      test('does not show loader during streaming when last part is a tool with output', async () => {
         const searchClient = createSearchClient();
         const chat = new Chat({});
 
@@ -473,7 +520,7 @@ export function createOptionsTests(
 
         expect(
           document.querySelector('.ais-ChatMessageLoader')
-        ).toBeInTheDocument();
+        ).not.toBeInTheDocument();
       });
 
       test('does not show loader during streaming when last part is text', async () => {

From fa6af667a2d9815744d1b410a59251449489dcd5 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Sun, 5 Apr 2026 16:57:00 +0100
Subject: [PATCH 05/23] add loader state to search tool

---
 .../src/widgets/chat/tools/SearchIndexTool.tsx            | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
index 33bfd686404..dff950ee152 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
@@ -82,6 +82,14 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
       );
     }, [items.length, input, output?.nbHits, applyFilters, onClose]);
 
+    if (message.state === 'input-streaming') {
+      return (
+        <div className="ais-ChatToolSearchIndex-loading">
+          Searching{input?.query ? ` for "${input.query}"` : ''}…
+        </div>
+      );
+    }
+
     return (
       <Carousel
         items={items}

From c09fd2ec8c637feeeb3d8c0e18c5928a4084b305 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 12:17:09 +0100
Subject: [PATCH 06/23] add loader component prop

---
 .../src/components/chat/ChatMessage.tsx                     | 6 ++++++
 .../src/components/chat/ChatMessages.tsx                    | 4 ++++
 .../src/components/chat/types.ts                            | 1 +
 3 files changed, 11 insertions(+)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index 21cc65c0f23..a3c03e7f28f 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -135,6 +135,10 @@ export type ChatMessageProps = ComponentProps<'article'> & {
    * Array of tools available for the assistant (for tool messages)
    */
   tools: ClientSideTools;
+  /**
+   * Loader component passed to tool layout components
+   */
+  loaderComponent?: (props: Record<string, unknown>) => JSX.Element;
   /**
    * Optional suggestions element
    */
@@ -171,6 +175,7 @@ export function createChatMessageComponent({ createElement }: Renderer) {
       indexUiState,
       setIndexUiState,
       onClose,
+      loaderComponent: LoaderComponent,
       translations: userTranslations,
       suggestionsElement,
       ...props
@@ -253,6 +258,7 @@ export function createChatMessageComponent({ createElement }: Renderer) {
                 addToolResult={boundAddToolResult}
                 applyFilters={tool.applyFilters}
                 onClose={onClose}
+                loaderComponent={LoaderComponent}
               />
             </div>
           );
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 2dc307a3860..913a241c93e 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -192,6 +192,7 @@ function createDefaultMessageComponent<
     onReload,
     onClose,
     actionsComponent,
+    loaderComponent,
     classNames,
     messageTranslations,
     translations,
@@ -208,6 +209,7 @@ function createDefaultMessageComponent<
     onReload: (messageId?: string) => void;
     onClose: () => void;
     actionsComponent?: ChatMessageProps['actionsComponent'];
+    loaderComponent?: ChatMessageProps['loaderComponent'];
     translations: ChatMessagesTranslations;
     classNames?: Partial<ChatMessageClassNames>;
     messageTranslations?: Partial<ChatMessageTranslations>;
@@ -247,6 +249,7 @@ function createDefaultMessageComponent<
         onClose={onClose}
         actions={defaultActions}
         actionsComponent={actionsComponent}
+        loaderComponent={loaderComponent}
         data-role={message.role}
         classNames={classNames}
         translations={messageTranslations}
@@ -376,6 +379,7 @@ export function createChatMessagesComponent({
                 setIndexUiState={setIndexUiState}
                 onReload={onReload}
                 actionsComponent={ActionsComponent}
+                loaderComponent={DefaultLoader}
                 onClose={onClose}
                 translations={translations}
                 classNames={messageClassNames}
diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index 558aabf4f31..72be161bfb0 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -466,6 +466,7 @@ export type ClientSideToolComponentProps = {
   onClose: () => void;
   addToolResult: AddToolResultWithOutput;
   applyFilters: (params: ApplyFiltersParams) => SearchParameters;
+  loaderComponent?: (props: Record<string, unknown>) => JSX.Element;
 };
 
 export type ClientSideToolComponent = (

From 68bc15b690e7fb049cfe0396cd655cb09fbe967d Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 12:44:07 +0100
Subject: [PATCH 07/23] add js template type

---
 .../src/components/chat/ChatMessage.tsx            |  3 ++-
 .../src/components/chat/types.ts                   |  3 ++-
 .../instantsearch.js/src/widgets/chat/chat.tsx     | 14 +++++++++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index a3c03e7f28f..95d757c6761 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -7,6 +7,7 @@ import { createButtonComponent } from '../Button';
 import { MenuIcon } from './icons';
 
 import type { ComponentProps, Renderer, VNode } from '../../types';
+import type { ChatMessageLoaderProps } from './ChatMessageLoader';
 import type {
   AddToolResultWithOutput,
   ChatMessageBase,
@@ -138,7 +139,7 @@ export type ChatMessageProps = ComponentProps<'article'> & {
   /**
    * Loader component passed to tool layout components
    */
-  loaderComponent?: (props: Record<string, unknown>) => JSX.Element;
+  loaderComponent?: (props: ChatMessageLoaderProps) => JSX.Element;
   /**
    * Optional suggestions element
    */
diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index 72be161bfb0..23ac43e4a4e 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -1,3 +1,4 @@
+import type { ChatMessageLoaderProps } from './ChatMessageLoader';
 import type { SearchParameters } from 'algoliasearch-helper';
 
 export type ChatStatus = 'ready' | 'submitted' | 'streaming' | 'error';
@@ -466,7 +467,7 @@ export type ClientSideToolComponentProps = {
   onClose: () => void;
   addToolResult: AddToolResultWithOutput;
   applyFilters: (params: ApplyFiltersParams) => SearchParameters;
-  loaderComponent?: (props: Record<string, unknown>) => JSX.Element;
+  loaderComponent?: (props: ChatMessageLoaderProps) => JSX.Element;
 };
 
 export type ClientSideToolComponent = (
diff --git a/packages/instantsearch.js/src/widgets/chat/chat.tsx b/packages/instantsearch.js/src/widgets/chat/chat.tsx
index 00d9cc5d8bd..cfd75fe2157 100644
--- a/packages/instantsearch.js/src/widgets/chat/chat.tsx
+++ b/packages/instantsearch.js/src/widgets/chat/chat.tsx
@@ -506,6 +506,17 @@ const createRenderer = <THit extends RecordWithObjectID = RecordWithObjectID>({
         widgetTool = tools[SearchIndexToolType];
       }
 
+      const loaderComponent = widgetTool?.templates?.loader
+        ? () => (
+            <TemplateComponent
+              templates={widgetTool.templates}
+              rootTagName="fragment"
+              templateKey="loader"
+              data={{}}
+            />
+          )
+        : undefined;
+
       toolsForUi[key] = {
         ...connectorTool,
         ...(widgetTool?.templates?.layout && {
@@ -517,7 +528,7 @@ const createRenderer = <THit extends RecordWithObjectID = RecordWithObjectID>({
                 templates={widgetTool.templates}
                 rootTagName="fragment"
                 templateKey="layout"
-                data={layoutComponentProps}
+                data={{ ...layoutComponentProps, loader: loaderComponent }}
               />
             );
           },
@@ -898,6 +909,7 @@ const createRenderer = <THit extends RecordWithObjectID = RecordWithObjectID>({
 
 export type UserClientSideToolTemplates = Partial<{
   layout: TemplateWithBindEvent<ClientSideToolComponentProps>;
+  loader: TemplateWithBindEvent<ClientSideToolComponentProps>;
 }>;
 
 type UserClientSideToolWithTemplate = Omit<

From d431b2f0bfa0d40d2ca2e940ccc52fc7f015f4c4 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 13:51:43 +0100
Subject: [PATCH 08/23] update types

---
 .../src/components/chat/ChatMessage.tsx       |  4 +--
 .../src/components/chat/ChatMessages.tsx      |  2 +-
 .../src/components/chat/types.ts              |  2 +-
 .../src/widgets/chat/chat.tsx                 | 29 +++++++++----------
 4 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index 1dc37ce6807..43245e75321 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -139,7 +139,7 @@ export type ChatMessageProps = ComponentProps<'article'> & {
   /**
    * Loader component passed to tool layout components
    */
-  loaderComponent?: (props: ChatMessageLoaderProps) => JSX.Element;
+  loaderComponent: (props: ChatMessageLoaderProps) => JSX.Element;
   /**
    * Optional suggestions element
    */
@@ -258,7 +258,7 @@ export function createChatMessageComponent({ createElement }: Renderer) {
                 setIndexUiState={setIndexUiState}
                 addToolResult={boundAddToolResult}
                 applyFilters={tool.applyFilters}
-                sendEvent={tool.sendEvent || (() => {})}
+                sendEvent={tool.sendEvent || (() => { })}
                 onClose={onClose}
                 loaderComponent={LoaderComponent}
               />
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index f9db8dfdc60..eed345ac039 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -245,7 +245,7 @@ function createDefaultMessageComponent<
     onFeedback?: (messageId: string, vote: 0 | 1) => void;
     feedbackState?: Record<string, 'sending' | 0 | 1>;
     actionsComponent?: ChatMessageProps['actionsComponent'];
-    loaderComponent?: ChatMessageProps['loaderComponent'];
+    loaderComponent: ChatMessageProps['loaderComponent'];
     translations: ChatMessagesTranslations;
     classNames?: Partial<ChatMessageClassNames>;
     messageTranslations?: Partial<ChatMessageTranslations>;
diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index 282f10be94a..11da99b048f 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -488,7 +488,7 @@ export type ClientSideToolComponentProps = {
   onClose: () => void;
   addToolResult: AddToolResultWithOutput;
   applyFilters: (params: ApplyFiltersParams) => SearchParameters;
-  loaderComponent?: (props: ChatMessageLoaderProps) => JSX.Element;
+  loaderComponent: (props: ChatMessageLoaderProps) => JSX.Element;
   sendEvent: SendEventForHits;
 };
 
diff --git a/packages/instantsearch.js/src/widgets/chat/chat.tsx b/packages/instantsearch.js/src/widgets/chat/chat.tsx
index c148610d0dc..35adc789417 100644
--- a/packages/instantsearch.js/src/widgets/chat/chat.tsx
+++ b/packages/instantsearch.js/src/widgets/chat/chat.tsx
@@ -97,7 +97,7 @@ function createCarouselTool<
     applyFilters,
     onClose,
     sendEvent,
-  }: ClientSideToolComponentProps) {
+  }: ClientSideToolTemplateData) {
     const input = message?.input as
       | {
           query: string;
@@ -533,29 +533,22 @@ const createRenderer = <THit extends RecordWithObjectID = RecordWithObjectID>({
         widgetTool = tools[SearchIndexToolType];
       }
 
-      const loaderComponent = widgetTool?.templates?.loader
-        ? () => (
-            <TemplateComponent
-              templates={widgetTool.templates}
-              rootTagName="fragment"
-              templateKey="loader"
-              data={{}}
-            />
-          )
-        : undefined;
-
       toolsForUi[key] = {
         ...connectorTool,
         ...(widgetTool?.templates?.layout && {
           layoutComponent: (
             layoutComponentProps: ClientSideToolComponentProps
           ) => {
+            const { loaderComponent: Loader, ...restProps } = layoutComponentProps;
             return (
               <TemplateComponent
                 templates={widgetTool.templates}
                 rootTagName="fragment"
                 templateKey="layout"
-                data={{ ...layoutComponentProps, loader: loaderComponent }}
+                data={{
+                  ...restProps,
+                  loader: () => <Loader />,
+                }}
               />
             );
           },
@@ -973,9 +966,15 @@ const createRenderer = <THit extends RecordWithObjectID = RecordWithObjectID>({
   };
 };
 
+export type ClientSideToolTemplateData = Omit<
+  ClientSideToolComponentProps,
+  'loaderComponent'
+> & {
+  loader: () => JSX.Element;
+};
+
 export type UserClientSideToolTemplates = Partial<{
-  layout: TemplateWithBindEvent<ClientSideToolComponentProps>;
-  loader: TemplateWithBindEvent<ClientSideToolComponentProps>;
+  layout: TemplateWithBindEvent<ClientSideToolTemplateData>;
 }>;
 
 type UserClientSideToolWithTemplate = Omit<

From 609b7dd58e6ed8466e477b13e47d3d331c3573b7 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 13:54:21 +0100
Subject: [PATCH 09/23] add test

---
 tests/common/widgets/chat/options.tsx | 154 ++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)

diff --git a/tests/common/widgets/chat/options.tsx b/tests/common/widgets/chat/options.tsx
index abd0be5efed..cb93ecc49e7 100644
--- a/tests/common/widgets/chat/options.tsx
+++ b/tests/common/widgets/chat/options.tsx
@@ -1030,6 +1030,160 @@ export function createOptionsTests(
         );
       });
 
+      test('passes loaderComponent to tool layout components', async () => {
+        const searchClient = createSearchClient();
+
+        const chat = new Chat({
+          messages: [
+            {
+              id: '1',
+              role: 'assistant',
+              parts: [
+                {
+                  type: 'tool-hello',
+                  toolCallId: '1',
+                  input: { text: 'hello' },
+                  state: 'output-available',
+                  output: 'hello',
+                },
+              ],
+            },
+          ],
+          id: 'chat-id',
+        });
+
+        await setup({
+          instantSearchOptions: {
+            indexName: 'indexName',
+            searchClient,
+          },
+          widgetParams: {
+            javascript: {
+              ...createDefaultWidgetParams(chat),
+              tools: {
+                hello: {
+                  templates: {
+                    layout: ({ loader }: any, { html }: any) =>
+                      html`<div id="tool-with-loader">
+                        ${loader ? loader() : null}
+                      </div>`,
+                  },
+                },
+              },
+            },
+            react: {
+              ...createDefaultWidgetParams(chat),
+              tools: {
+                hello: {
+                  layoutComponent: ({
+                    loaderComponent: Loader,
+                  }: {
+                    loaderComponent?: (props: any) => React.ReactElement;
+                  }) => (
+                    <div id="tool-with-loader">
+                      {Loader ? <Loader /> : null}
+                    </div>
+                  ),
+                },
+              },
+            },
+            vue: {},
+          },
+        });
+
+        await openChat(act);
+
+        expect(
+          document.querySelector('#tool-with-loader')
+        ).toBeInTheDocument();
+        expect(
+          document.querySelector(
+            '#tool-with-loader .ais-ChatMessageLoader'
+          )
+        ).toBeInTheDocument();
+      });
+
+      test('loaderComponent renders custom loader when messagesLoaderComponent is provided', async () => {
+        const searchClient = createSearchClient();
+
+        const chat = new Chat({
+          messages: [
+            {
+              id: '1',
+              role: 'assistant',
+              parts: [
+                {
+                  type: 'tool-hello',
+                  toolCallId: '1',
+                  input: { text: 'hello' },
+                  state: 'output-available',
+                  output: 'hello',
+                },
+              ],
+            },
+          ],
+          id: 'chat-id',
+        });
+
+        const CustomLoader = () => (
+          <div className="custom-loader">Loading...</div>
+        );
+
+        await setup({
+          instantSearchOptions: {
+            indexName: 'indexName',
+            searchClient,
+          },
+          widgetParams: {
+            javascript: {
+              ...createDefaultWidgetParams(chat),
+              templates: {
+                messages: {
+                  loader: '<div class="custom-loader">Loading...</div>',
+                },
+              },
+              tools: {
+                hello: {
+                  templates: {
+                    layout: ({ loader }: any, { html }: any) =>
+                      html`<div id="tool-custom-loader">
+                        ${loader ? loader() : null}
+                      </div>`,
+                  },
+                },
+              },
+            },
+            react: {
+              ...createDefaultWidgetParams(chat),
+              messagesLoaderComponent: CustomLoader,
+              tools: {
+                hello: {
+                  layoutComponent: ({
+                    loaderComponent: Loader,
+                  }: {
+                    loaderComponent?: (props: any) => React.ReactElement;
+                  }) => (
+                    <div id="tool-custom-loader">
+                      {Loader ? <Loader /> : null}
+                    </div>
+                  ),
+                },
+              },
+            },
+            vue: {},
+          },
+        });
+
+        await openChat(act);
+
+        expect(
+          document.querySelector('#tool-custom-loader')
+        ).toBeInTheDocument();
+        expect(
+          document.querySelector('#tool-custom-loader .custom-loader')
+        ).toBeInTheDocument();
+      });
+
       test('shows actions for assistant messages when status is ready', async () => {
         const searchClient = createSearchClient();
 

From 2aa21f6adf344618ced7bebc04ae1fcf18353467 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 14:36:44 +0100
Subject: [PATCH 10/23] fix lint

---
 .../src/components/chat/__tests__/ChatMessage.test.tsx      | 6 ++++++
 .../widgets/chat/tools/__tests__/SearchIndexTool.test.tsx   | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/packages/instantsearch-ui-components/src/components/chat/__tests__/ChatMessage.test.tsx b/packages/instantsearch-ui-components/src/components/chat/__tests__/ChatMessage.test.tsx
index 1dcc0e2440c..2a58ca706e1 100644
--- a/packages/instantsearch-ui-components/src/components/chat/__tests__/ChatMessage.test.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/__tests__/ChatMessage.test.tsx
@@ -21,6 +21,7 @@ describe('ChatMessage', () => {
         message={{ role: 'user', id: '1', parts: [] }}
         status="ready"
         tools={{}}
+        loaderComponent={jest.fn()}
         onClose={jest.fn()}
       />
     );
@@ -66,6 +67,7 @@ describe('ChatMessage', () => {
           actions: 'actions',
         }}
         tools={{}}
+        loaderComponent={jest.fn()}
         onClose={jest.fn()}
       />
     );
@@ -104,6 +106,7 @@ describe('ChatMessage', () => {
           }}
           status="ready"
           tools={{}}
+          loaderComponent={jest.fn()}
           onClose={jest.fn()}
         />
         <ChatMessage
@@ -116,6 +119,7 @@ describe('ChatMessage', () => {
           }}
           status="ready"
           tools={{}}
+          loaderComponent={jest.fn()}
           onClose={jest.fn()}
         />
         <ChatMessage
@@ -128,6 +132,7 @@ describe('ChatMessage', () => {
           }}
           status="ready"
           tools={{}}
+          loaderComponent={jest.fn()}
           onClose={jest.fn()}
         />
       </div>
@@ -235,6 +240,7 @@ describe('ChatMessage', () => {
             applyFilters: jest.fn(),
           },
         }}
+        loaderComponent={jest.fn()}
         onClose={jest.fn()}
       />
     );
diff --git a/packages/react-instantsearch/src/widgets/chat/tools/__tests__/SearchIndexTool.test.tsx b/packages/react-instantsearch/src/widgets/chat/tools/__tests__/SearchIndexTool.test.tsx
index ea1b1f30399..12c68583424 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/__tests__/SearchIndexTool.test.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/__tests__/SearchIndexTool.test.tsx
@@ -47,6 +47,7 @@ describe('createCarouselTool', () => {
           indexUiState={{}}
           addToolResult={jest.fn()}
           setIndexUiState={jest.fn()}
+          loaderComponent={jest.fn()}
           sendEvent={jest.fn()}
         />
       );
@@ -81,6 +82,7 @@ describe('createCarouselTool', () => {
           indexUiState={{}}
           addToolResult={jest.fn()}
           setIndexUiState={jest.fn()}
+          loaderComponent={jest.fn()}
           sendEvent={jest.fn()}
         />
       );

From 82f571f27a06372d5e9941e0c86c8b6b167b0be5 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 14:42:20 +0100
Subject: [PATCH 11/23] update bundlesize

---
 bundlesize.config.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bundlesize.config.json b/bundlesize.config.json
index 7572a04caff..a1bc9fb5a58 100644
--- a/bundlesize.config.json
+++ b/bundlesize.config.json
@@ -14,7 +14,7 @@
     },
     {
       "path": "./packages/instantsearch.js/dist/instantsearch.development.js",
-      "maxSize": "251.25 kB"
+      "maxSize": "252.75 kB"
     },
     {
       "path": "packages/react-instantsearch-core/dist/umd/ReactInstantSearchCore.min.js",

From 7e1d9f4a98fef94ba8be03e201cd7387c6fd8539 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Tue, 7 Apr 2026 14:46:40 +0100
Subject: [PATCH 12/23] revert example

---
 examples/react/getting-started/src/App.tsx | 213 ---------------------
 1 file changed, 213 deletions(-)

diff --git a/examples/react/getting-started/src/App.tsx b/examples/react/getting-started/src/App.tsx
index d60d2b2770b..7602bfab9a0 100644
--- a/examples/react/getting-started/src/App.tsx
+++ b/examples/react/getting-started/src/App.tsx
@@ -27,216 +27,6 @@ const searchClient = algoliasearch(
   '6be0576ff61c053d5f9a3225e2a90f76'
 );
 
-const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
-const TOOL_OUTPUT_STEP_DELAY_MS = 900;
-
-const normalizeToolOutputEvent = (event: any): any => {
-  if (event?.type !== 'tool-output-available' || !event.output) {
-    return event;
-  }
-
-  const output = event.output as Record<string, any>;
-
-  if (Array.isArray(output.hits)) {
-    return event;
-  }
-
-  if (
-    Array.isArray(output.results) &&
-    output.results.length > 0 &&
-    Array.isArray(output.results[0]?.hits)
-  ) {
-    const hits = output.results[0].hits;
-    return {
-      ...event,
-      output: {
-        ...output,
-        hits,
-        nbHits: output.nbHits ?? hits.length,
-      },
-    };
-  }
-
-  return event;
-};
-
-const getProgressiveToolOutputEvents = (event: any): any[] => {
-  if (event?.type !== 'tool-output-available' || !event.output) {
-    return [];
-  }
-
-  const output = event.output as Record<string, any>;
-
-  if (Array.isArray(output.hits) && output.hits.length > 1) {
-    return output.hits.slice(0, -1).map((_: any, index: number) => ({
-      ...event,
-      preliminary: true,
-      output: {
-        ...output,
-        hits: output.hits.slice(0, index + 1),
-      },
-    }));
-  }
-
-  if (Array.isArray(output.results) && output.results.length > 0) {
-    const firstResultWithHitsIndex = output.results.findIndex(
-      (result: any) => Array.isArray(result?.hits) && result.hits.length > 1
-    );
-
-    if (firstResultWithHitsIndex === -1) {
-      return [];
-    }
-
-    const hits = output.results[firstResultWithHitsIndex].hits;
-    return hits.slice(0, -1).map((_: any, index: number) => ({
-      ...event,
-      preliminary: true,
-      output: {
-        ...output,
-        results: output.results.map((result: any, resultIndex: number) =>
-          resultIndex === firstResultWithHitsIndex
-            ? {
-                ...result,
-                hits: hits.slice(0, index + 1),
-              }
-            : result
-        ),
-      },
-    }));
-  }
-
-  return [];
-};
-
-const delayedChatFetch: typeof fetch = async (input, init) => {
-  const response = await fetch(input, init);
-
-  const isEventStream =
-    response.headers.get('content-type')?.includes('text/event-stream') ??
-    false;
-
-  if (!response.body || !isEventStream) {
-    return response;
-  }
-
-  const reader = response.body.getReader();
-  const decoder = new TextDecoder();
-  const encoder = new TextEncoder();
-  let hasInjectedOutputDelay = false;
-  let pendingText = '';
-
-  const delayedBody = new ReadableStream<Uint8Array>({
-    async start(controller) {
-      const emitLine = async (line: string): Promise<void> => {
-        if (!line.startsWith('data: ')) {
-          controller.enqueue(encoder.encode(line));
-          return;
-        }
-
-        const payload = line.slice(6).trim();
-        if (payload === '[DONE]') {
-          controller.enqueue(encoder.encode(line));
-          return;
-        }
-
-        let parsedEvent: any;
-        try {
-          parsedEvent = JSON.parse(payload);
-        } catch {
-          controller.enqueue(encoder.encode(line));
-          return;
-        }
-
-        if (
-          !hasInjectedOutputDelay &&
-          parsedEvent?.type === 'tool-output-available'
-        ) {
-          const normalizedToolOutputEvent =
-            normalizeToolOutputEvent(parsedEvent);
-          const progressiveEvents = getProgressiveToolOutputEvents(
-            normalizedToolOutputEvent
-          );
-
-          if (progressiveEvents.length > 0) {
-            hasInjectedOutputDelay = true;
-
-            const emitProgressiveOutput = (index: number): Promise<void> => {
-              if (index >= progressiveEvents.length) {
-                controller.enqueue(
-                  encoder.encode(
-                    `data: ${JSON.stringify(normalizedToolOutputEvent)}\n`
-                  )
-                );
-                controller.enqueue(encoder.encode('\n'));
-                return Promise.resolve();
-              }
-
-              controller.enqueue(
-                encoder.encode(
-                  `data: ${JSON.stringify(progressiveEvents[index])}\n`
-                )
-              );
-              controller.enqueue(encoder.encode('\n'));
-
-              return sleep(TOOL_OUTPUT_STEP_DELAY_MS).then(() =>
-                emitProgressiveOutput(index + 1)
-              );
-            };
-
-            return emitProgressiveOutput(0);
-          }
-        }
-
-        controller.enqueue(encoder.encode(line));
-      };
-
-      const processPendingLines = (): Promise<void> => {
-        const lineBreakIndex = pendingText.indexOf('\n');
-        if (lineBreakIndex === -1) {
-          return Promise.resolve();
-        }
-
-        const line = pendingText.slice(0, lineBreakIndex + 1);
-        pendingText = pendingText.slice(lineBreakIndex + 1);
-
-        return emitLine(line).then(() => processPendingLines());
-      };
-
-      const pump = (): Promise<void> =>
-        reader.read().then(({ done, value }) => {
-          if (done) {
-            if (pendingText) {
-              controller.enqueue(encoder.encode(pendingText));
-            }
-            controller.close();
-            return Promise.resolve();
-          }
-
-          if (!value) {
-            return pump();
-          }
-
-          pendingText += decoder.decode(value, { stream: true });
-          return processPendingLines().then(() => pump());
-        });
-
-      try {
-        await pump();
-      } catch (error) {
-        controller.error(error);
-      } finally {
-        reader.releaseLock();
-      }
-    },
-  });
-
-  return new Response(delayedBody, {
-    status: response.status,
-    statusText: response.statusText,
-    headers: response.headers,
-  });
-};
-
 export function App() {
   return (
     <div>
@@ -305,9 +95,6 @@ export function App() {
             agentId="eedef238-5468-470d-bc37-f99fa741bd25"
             feedback={true}
             itemComponent={ItemComponent}
-            transport={{
-              fetch: delayedChatFetch,
-            }}
           />
         </InstantSearch>
       </div>

From dc5a32bb3dcc8335e7acb96c37662637289e0d8f Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Wed, 8 Apr 2026 14:10:59 +0100
Subject: [PATCH 13/23] add option to show loader for input streaming

---
 .../src/components/chat/ChatMessage.tsx       |  9 +++++++
 .../src/components/chat/ChatMessageLoader.tsx |  2 +-
 .../src/components/chat/ChatMessages.tsx      | 25 +++++++++++++++++--
 .../src/components/chat/types.ts              |  1 +
 4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index 43245e75321..ede99d83dfe 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -243,6 +243,15 @@ export function createChatMessageComponent({ createElement }: Renderer) {
               toolCallId: toolMessage.toolCallId,
             });
 
+          const showInlineLoader =
+            tool.showLoaderDuringStreaming &&
+            toolMessage.state === 'input-streaming' &&
+            LoaderComponent;
+
+          if (showInlineLoader) {
+            return null;
+          }
+
           if (!ToolLayoutComponent) {
             return null;
           }
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessageLoader.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessageLoader.tsx
index 32ce1590a31..db193f9e59a 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessageLoader.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessageLoader.tsx
@@ -24,7 +24,7 @@ export function createChatMessageLoaderComponent({
   return function ChatMessageLoader(userProps: ChatMessageLoaderProps) {
     const { translations: userTranslations, ...props } = userProps;
     const translations: Required<ChatMessageLoaderTranslations> = {
-      loaderText: 'Thinking...',
+      loaderText: '',
       ...userTranslations,
     };
 
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index eed345ac039..298cd6083e8 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -1,10 +1,12 @@
 /** @jsx createElement */
 
 import { cx } from '../../lib';
+import { startsWith } from '../../lib';
 import {
   getTextContent,
   hasTextContent,
   isPartText,
+  isPartTool,
   isToolPartActivelyRendering,
 } from '../../lib/utils/chat';
 import { createButtonComponent } from '../Button';
@@ -31,7 +33,7 @@ import type {
 } from './ChatMessage';
 import type { ChatMessageErrorProps } from './ChatMessageError';
 import type { ChatMessageLoaderProps } from './ChatMessageLoader';
-import type { ChatMessageBase, ChatStatus, ClientSideTools } from './types';
+import type { ChatMessageBase, ChatStatus, ClientSideTool, ClientSideTools } from './types';
 
 export type ChatMessagesTranslations = {
   /**
@@ -417,13 +419,32 @@ export function createChatMessagesComponent({
     const lastPart = lastMessage?.parts?.[lastMessage.parts.length - 1];
     const isWaitingForResponse = status === 'submitted';
     const isStreamingWithNoContent = status === 'streaming' && !lastPart;
+
+    // Check if the last tool part has showLoaderDuringStreaming enabled and is in input-streaming state
+    // if so, it renders nothing inline and we should show the global loader instead
+    const isToolDeferringToGlobalLoader =
+      lastPart &&
+      isPartTool(lastPart) &&
+      lastPart.state === 'input-streaming' &&
+      (() => {
+        const toolName = lastPart.type.replace('tool-', '');
+        let tool: ClientSideTool | undefined = tools[toolName];
+        if (!tool) {
+          tool = Object.entries(tools).find(([key]) =>
+            startsWith(toolName, `${key}_`)
+          )?.[1];
+        }
+        return tool?.showLoaderDuringStreaming;
+      })();
+
     const isStreamingNonTextContent =
       status === 'streaming' && lastPart && !(isPartText(lastPart) || isToolPartActivelyRendering(lastPart));
 
     const showLoader =
       isWaitingForResponse ||
       isStreamingWithNoContent ||
-      isStreamingNonTextContent;
+      isStreamingNonTextContent ||
+      isToolDeferringToGlobalLoader;
 
     const DefaultMessage = MessageComponent || DefaultMessageComponent;
     const DefaultLoader = LoaderComponent || DefaultLoaderComponent;
diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index 11da99b048f..f9f699a2378 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -498,6 +498,7 @@ export type ClientSideToolComponent = (
 
 export type ClientSideTool = {
   layoutComponent?: ClientSideToolComponent;
+  showLoaderDuringStreaming?: boolean;
   addToolResult: AddToolResult;
   sendEvent?: SendEventForHits;
   onToolCall?: (

From 108af757b45b18a0e276f949329f0cabf0a19939 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Wed, 8 Apr 2026 14:48:35 +0100
Subject: [PATCH 14/23] update bundlesize

---
 bundlesize.config.json | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/bundlesize.config.json b/bundlesize.config.json
index 453e6767773..3c3bbddb037 100644
--- a/bundlesize.config.json
+++ b/bundlesize.config.json
@@ -10,11 +10,11 @@
     },
     {
       "path": "./packages/instantsearch.js/dist/instantsearch.production.min.js",
-      "maxSize": "121.25 kB"
+      "maxSize": "122 kB"
     },
     {
       "path": "./packages/instantsearch.js/dist/instantsearch.development.js",
-      "maxSize": "253 kB"
+      "maxSize": "254.25 kB"
     },
     {
       "path": "packages/react-instantsearch-core/dist/umd/ReactInstantSearchCore.min.js",

From 6cdad46ff6d67cb3f244b41b1e3661496a5932c1 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Wed, 8 Apr 2026 14:52:53 +0100
Subject: [PATCH 15/23] fix indents

---
 .../src/components/chat/types.ts              | 134 +++++++++---------
 1 file changed, 66 insertions(+), 68 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index f9f699a2378..bdbe76e02ca 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -121,39 +121,38 @@ export type ToolUIPart<TTools extends UITools = UITools> = ValueOf<{
     toolCallId: string;
   } & (
     | {
-      state: 'input-streaming';
-      input: DeepPartial<TTools[NAME]['input']> | undefined;
-      rawInput?: string;
-      providerExecuted?: boolean;
-      output?: never;
-      errorText?: never;
-    }
+        state: 'input-streaming';
+        input: DeepPartial<TTools[NAME]['input']> | undefined;
+        providerExecuted?: boolean;
+        output?: never;
+        errorText?: never;
+      }
     | {
-      state: 'input-available';
-      input: TTools[NAME]['input'];
-      providerExecuted?: boolean;
-      output?: never;
-      errorText?: never;
-      callProviderMetadata?: ProviderMetadata;
-    }
+        state: 'input-available';
+        input: TTools[NAME]['input'];
+        providerExecuted?: boolean;
+        output?: never;
+        errorText?: never;
+        callProviderMetadata?: ProviderMetadata;
+      }
     | {
-      state: 'output-available';
-      input: TTools[NAME]['input'];
-      output: TTools[NAME]['output'];
-      errorText?: never;
-      providerExecuted?: boolean;
-      callProviderMetadata?: ProviderMetadata;
-      preliminary?: boolean;
-    }
+        state: 'output-available';
+        input: TTools[NAME]['input'];
+        output: TTools[NAME]['output'];
+        errorText?: never;
+        providerExecuted?: boolean;
+        callProviderMetadata?: ProviderMetadata;
+        preliminary?: boolean;
+      }
     | {
-      state: 'output-error';
-      input: TTools[NAME]['input'] | undefined;
-      rawInput?: unknown;
-      output?: never;
-      errorText: string;
-      providerExecuted?: boolean;
-      callProviderMetadata?: ProviderMetadata;
-    }
+        state: 'output-error';
+        input: TTools[NAME]['input'] | undefined;
+        rawInput?: unknown;
+        output?: never;
+        errorText: string;
+        providerExecuted?: boolean;
+        callProviderMetadata?: ProviderMetadata;
+      }
   );
 }>;
 
@@ -165,21 +164,20 @@ export type DynamicToolUIPart = {
   toolName: string;
   toolCallId: string;
 } & (
-    | {
+  | {
       state: 'input-streaming';
       input: unknown | undefined;
-      rawInput?: string;
       output?: never;
       errorText?: never;
     }
-    | {
+  | {
       state: 'input-available';
       input: unknown;
       output?: never;
       errorText?: never;
       callProviderMetadata?: ProviderMetadata;
     }
-    | {
+  | {
       state: 'output-available';
       input: unknown;
       output: unknown;
@@ -187,14 +185,14 @@ export type DynamicToolUIPart = {
       callProviderMetadata?: ProviderMetadata;
       preliminary?: boolean;
     }
-    | {
+  | {
       state: 'output-error';
       input: unknown;
       output?: never;
       errorText: string;
       callProviderMetadata?: ProviderMetadata;
     }
-  );
+);
 
 /**
  * All possible message part types.
@@ -297,23 +295,23 @@ export type ChatOnErrorCallback = (error: Error) => void;
  */
 export type InferUIMessageToolCall<TUIMessage extends UIMessage> =
   | ValueOf<{
-    [NAME in keyof InferUIMessageTools<TUIMessage>]: {
-      toolName: NAME & string;
+      [NAME in keyof InferUIMessageTools<TUIMessage>]: {
+        toolName: NAME & string;
+        toolCallId: string;
+        input: InferUIMessageTools<TUIMessage>[NAME] extends {
+          input: infer INPUT;
+        }
+          ? INPUT
+          : never;
+        dynamic?: false;
+      };
+    }>
+  | {
+      toolName: string;
       toolCallId: string;
-      input: InferUIMessageTools<TUIMessage>[NAME] extends {
-        input: infer INPUT;
-      }
-      ? INPUT
-      : never;
-      dynamic?: false;
+      input: unknown;
+      dynamic: true;
     };
-  }>
-  | {
-    toolName: string;
-    toolCallId: string;
-    input: unknown;
-    dynamic: true;
-  };
 
 /**
  * Optional callback function that is invoked when a tool call is received.
@@ -401,25 +399,25 @@ export interface AbstractChat<TUIMessage extends UIMessage> {
   sendMessage: (
     message?:
       | (Omit<TUIMessage, 'id' | 'role'> & {
-        id?: TUIMessage['id'];
-        role?: TUIMessage['role'];
-        text?: never;
-        files?: never;
-        messageId?: string;
-      })
+          id?: TUIMessage['id'];
+          role?: TUIMessage['role'];
+          text?: never;
+          files?: never;
+          messageId?: string;
+        })
       | {
-        text: string;
-        files?: FileList | FileUIPart[];
-        metadata?: InferUIMessageMetadata<TUIMessage>;
-        parts?: never;
-        messageId?: string;
-      }
+          text: string;
+          files?: FileList | FileUIPart[];
+          metadata?: InferUIMessageMetadata<TUIMessage>;
+          parts?: never;
+          messageId?: string;
+        }
       | {
-        files: FileList | FileUIPart[];
-        metadata?: InferUIMessageMetadata<TUIMessage>;
-        parts?: never;
-        messageId?: string;
-      },
+          files: FileList | FileUIPart[];
+          metadata?: InferUIMessageMetadata<TUIMessage>;
+          parts?: never;
+          messageId?: string;
+        },
     options?: { headers?: Record<string, string> | Headers; body?: object }
   ) => Promise<void>;
 

From 08721f1c0e5fa12581852ce5f2775084838a3822 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Wed, 8 Apr 2026 15:40:10 +0100
Subject: [PATCH 16/23] remove not needed code

---
 .../src/components/chat/ChatMessage.tsx             |  6 ++++--
 .../src/components/chat/ChatMessages.tsx            |  3 +--
 .../src/lib/utils/chat.ts                           | 13 +------------
 3 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index ede99d83dfe..e07745c4f59 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -243,12 +243,14 @@ export function createChatMessageComponent({ createElement }: Renderer) {
               toolCallId: toolMessage.toolCallId,
             });
 
-          const showInlineLoader =
+          const showBaseLoader =
             tool.showLoaderDuringStreaming &&
             toolMessage.state === 'input-streaming' &&
             LoaderComponent;
 
-          if (showInlineLoader) {
+          // If the tool is still streaming and has indicated to show the base loader,
+          // we don't render the tool layout component.
+          if (showBaseLoader) {
             return null;
           }
 
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 298cd6083e8..869c26b5ccb 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -7,7 +7,6 @@ import {
   hasTextContent,
   isPartText,
   isPartTool,
-  isToolPartActivelyRendering,
 } from '../../lib/utils/chat';
 import { createButtonComponent } from '../Button';
 
@@ -438,7 +437,7 @@ export function createChatMessagesComponent({
       })();
 
     const isStreamingNonTextContent =
-      status === 'streaming' && lastPart && !(isPartText(lastPart) || isToolPartActivelyRendering(lastPart));
+      status === 'streaming' && lastPart && !isPartText(lastPart);
 
     const showLoader =
       isWaitingForResponse ||
diff --git a/packages/instantsearch-ui-components/src/lib/utils/chat.ts b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
index 55da19f4294..a9883402f46 100644
--- a/packages/instantsearch-ui-components/src/lib/utils/chat.ts
+++ b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
@@ -23,15 +23,4 @@ export const isPartTool = (
   part: ChatMessageBase['parts'][number]
 ): part is ChatToolMessage => {
   return startsWith(part.type, 'tool-');
-};
-
-export const isToolPartActivelyRendering = (
-  part: ChatMessageBase['parts'][number]
-): boolean => {
-  return (
-    isPartTool(part) &&
-    (part.state === 'input-streaming' ||
-      part.state === 'output-available' ||
-      part.state === 'output-error')
-  );
-};
+};
\ No newline at end of file

From 2098ffa89d82430821e410414117a4097a2a8588 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Wed, 8 Apr 2026 15:43:32 +0100
Subject: [PATCH 17/23] update search tool loading indicator

---
 packages/instantsearch.js/src/widgets/chat/chat.tsx       | 8 ++++++++
 .../src/widgets/chat/tools/SearchIndexTool.tsx            | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/packages/instantsearch.js/src/widgets/chat/chat.tsx b/packages/instantsearch.js/src/widgets/chat/chat.tsx
index 35adc789417..6920bb8b7e1 100644
--- a/packages/instantsearch.js/src/widgets/chat/chat.tsx
+++ b/packages/instantsearch.js/src/widgets/chat/chat.tsx
@@ -143,6 +143,14 @@ function createCarouselTool<
       );
     }, [items.length, input, output?.nbHits, applyFilters, onClose]);
 
+    if (message.state === 'input-streaming') {
+      return (
+        <div className="ais-ChatToolSearchIndex-loading">
+          Searching…
+        </div>
+      );
+    }
+
     return carousel({
       showNavigation: false,
       templates: {
diff --git a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
index 89d6ac1a62c..154b8eb7604 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
@@ -96,7 +96,7 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
     if (message.state === 'input-streaming') {
       return (
         <div className="ais-ChatToolSearchIndex-loading">
-          Searching{input?.query ? ` for "${input.query}"` : ''}…
+          Searching…
         </div>
       );
     }

From 2d97af6381be68b881f79c5f10a411f82ec2cf6f Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Thu, 9 Apr 2026 10:45:06 +0100
Subject: [PATCH 18/23] default input streaming to false

---
 .../src/components/chat/ChatMessage.tsx                | 10 +++-------
 .../src/components/chat/ChatMessages.tsx               |  9 ++++++---
 .../src/connectors/chat/connectChat.ts                 |  1 +
 packages/instantsearch.js/src/widgets/chat/chat.tsx    |  1 +
 .../src/widgets/chat/tools/SearchIndexTool.tsx         |  1 +
 tests/common/widgets/chat/options.tsx                  |  6 +++---
 6 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index e07745c4f59..9ad5eb6a907 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -243,14 +243,10 @@ export function createChatMessageComponent({ createElement }: Renderer) {
               toolCallId: toolMessage.toolCallId,
             });
 
-          const showBaseLoader =
-            tool.showLoaderDuringStreaming &&
+          if (
             toolMessage.state === 'input-streaming' &&
-            LoaderComponent;
-
-          // If the tool is still streaming and has indicated to show the base loader,
-          // we don't render the tool layout component.
-          if (showBaseLoader) {
+            tool.showLoaderDuringStreaming
+          ) {
             return null;
           }
 
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 869c26b5ccb..24d10e1f50a 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -419,8 +419,8 @@ export function createChatMessagesComponent({
     const isWaitingForResponse = status === 'submitted';
     const isStreamingWithNoContent = status === 'streaming' && !lastPart;
 
-    // Check if the last tool part has showLoaderDuringStreaming enabled and is in input-streaming state
-    // if so, it renders nothing inline and we should show the global loader instead
+    // Check if the tool opted out of the global loader during input-streaming
+    // via showLoaderDuringStreaming: false.
     const isToolDeferringToGlobalLoader =
       lastPart &&
       isPartTool(lastPart) &&
@@ -437,7 +437,10 @@ export function createChatMessagesComponent({
       })();
 
     const isStreamingNonTextContent =
-      status === 'streaming' && lastPart && !isPartText(lastPart);
+      status === 'streaming' &&
+      lastPart &&
+      !isPartText(lastPart) &&
+      !(isPartTool(lastPart) && lastPart.state === 'output-available');
 
     const showLoader =
       isWaitingForResponse ||
diff --git a/packages/instantsearch.js/src/connectors/chat/connectChat.ts b/packages/instantsearch.js/src/connectors/chat/connectChat.ts
index 9d88d3cce56..c9c18c5c39a 100644
--- a/packages/instantsearch.js/src/connectors/chat/connectChat.ts
+++ b/packages/instantsearch.js/src/connectors/chat/connectChat.ts
@@ -599,6 +599,7 @@ export default (function connectChat<TWidgetParams extends UnknownWidgetParams>(
         const toolsWithAddToolResult: ClientSideTools = {};
         Object.entries(tools).forEach(([key, tool]) => {
           const toolWithAddToolResult: ClientSideTool = {
+            showLoaderDuringStreaming: true,
             ...tool,
             addToolResult: _chatInstance.addToolResult,
             applyFilters,
diff --git a/packages/instantsearch.js/src/widgets/chat/chat.tsx b/packages/instantsearch.js/src/widgets/chat/chat.tsx
index 6920bb8b7e1..f5be7f1ebd5 100644
--- a/packages/instantsearch.js/src/widgets/chat/chat.tsx
+++ b/packages/instantsearch.js/src/widgets/chat/chat.tsx
@@ -265,6 +265,7 @@ function createCarouselTool<
 
   return {
     templates: { layout: SearchLayoutComponent },
+    showLoaderDuringStreaming: false,
   };
 }
 
diff --git a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
index 154b8eb7604..406de1e806e 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
@@ -205,6 +205,7 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
 
   return {
     layoutComponent: SearchLayoutComponent,
+    showLoaderDuringStreaming: false,
   };
 }
 
diff --git a/tests/common/widgets/chat/options.tsx b/tests/common/widgets/chat/options.tsx
index 5e2ce103614..71e4f73a07d 100644
--- a/tests/common/widgets/chat/options.tsx
+++ b/tests/common/widgets/chat/options.tsx
@@ -385,7 +385,7 @@ export function createOptionsTests(
         ).toBeInTheDocument();
       });
 
-      test('does not show loader during streaming when last part is a tool with streaming input', async () => {
+      test('shows loader during streaming when last part is a tool with streaming input', async () => {
         const searchClient = createSearchClient();
         const chat = new Chat({});
 
@@ -415,7 +415,7 @@ export function createOptionsTests(
               role: 'assistant',
               parts: [
                 {
-                  type: `tool-${SearchIndexToolType}`,
+                  type: 'tool-some_tool',
                   toolCallId: '1',
                   state: 'input-streaming',
                   input: undefined,
@@ -429,7 +429,7 @@ export function createOptionsTests(
 
         expect(
           document.querySelector('.ais-ChatMessageLoader')
-        ).not.toBeInTheDocument();
+        ).toBeInTheDocument();
       });
 
       test('shows loader during streaming when last part is a tool with input available', async () => {

From 7c919206cff404a3eeb47f93adb067bbd3812472 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Fri, 10 Apr 2026 01:48:15 +0100
Subject: [PATCH 19/23] move loader logic

---
 .../src/components/chat/ChatMessages.tsx      | 60 +++++++++----------
 .../src/lib/utils/chat.ts                     | 22 ++++++-
 2 files changed, 47 insertions(+), 35 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 24d10e1f50a..2f53483ace8 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -1,8 +1,8 @@
 /** @jsx createElement */
 
 import { cx } from '../../lib';
-import { startsWith } from '../../lib';
 import {
+  findTool,
   getTextContent,
   hasTextContent,
   isPartText,
@@ -32,7 +32,7 @@ import type {
 } from './ChatMessage';
 import type { ChatMessageErrorProps } from './ChatMessageError';
 import type { ChatMessageLoaderProps } from './ChatMessageLoader';
-import type { ChatMessageBase, ChatStatus, ClientSideTool, ClientSideTools } from './types';
+import type { ChatMessageBase, ChatStatus, ClientSideTools } from './types';
 
 export type ChatMessagesTranslations = {
   /**
@@ -416,37 +416,7 @@ export function createChatMessagesComponent({
 
     const lastMessage = messages[messages.length - 1];
     const lastPart = lastMessage?.parts?.[lastMessage.parts.length - 1];
-    const isWaitingForResponse = status === 'submitted';
-    const isStreamingWithNoContent = status === 'streaming' && !lastPart;
-
-    // Check if the tool opted out of the global loader during input-streaming
-    // via showLoaderDuringStreaming: false.
-    const isToolDeferringToGlobalLoader =
-      lastPart &&
-      isPartTool(lastPart) &&
-      lastPart.state === 'input-streaming' &&
-      (() => {
-        const toolName = lastPart.type.replace('tool-', '');
-        let tool: ClientSideTool | undefined = tools[toolName];
-        if (!tool) {
-          tool = Object.entries(tools).find(([key]) =>
-            startsWith(toolName, `${key}_`)
-          )?.[1];
-        }
-        return tool?.showLoaderDuringStreaming;
-      })();
-
-    const isStreamingNonTextContent =
-      status === 'streaming' &&
-      lastPart &&
-      !isPartText(lastPart) &&
-      !(isPartTool(lastPart) && lastPart.state === 'output-available');
-
-    const showLoader =
-      isWaitingForResponse ||
-      isStreamingWithNoContent ||
-      isStreamingNonTextContent ||
-      isToolDeferringToGlobalLoader;
+    const showLoader = getShowLoader(status, lastPart, tools);
 
     const DefaultMessage = MessageComponent || DefaultMessageComponent;
     const DefaultLoader = LoaderComponent || DefaultLoaderComponent;
@@ -534,3 +504,27 @@ export function createChatMessagesComponent({
     );
   };
 }
+
+const getShowLoader = (
+  status: ChatStatus,
+  lastPart: ChatMessageBase['parts'][number] | undefined,
+  tools: ClientSideTools
+): boolean => {
+  if (status !== 'submitted' && status !== 'streaming') return false;
+  if (status === 'submitted') return true;
+
+  if (!lastPart) return true;
+  if (isPartText(lastPart)) return false;
+
+  if (isPartTool(lastPart)) {
+    if (lastPart.state === 'output-available') return false;
+    if (lastPart.state === 'input-streaming') {
+      const tool = findTool(lastPart.type, tools);
+      return tool?.showLoaderDuringStreaming !== false;
+    }
+    return true;
+  }
+
+  return true;
+};
+
diff --git a/packages/instantsearch-ui-components/src/lib/utils/chat.ts b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
index a9883402f46..abf89a61454 100644
--- a/packages/instantsearch-ui-components/src/lib/utils/chat.ts
+++ b/packages/instantsearch-ui-components/src/lib/utils/chat.ts
@@ -1,7 +1,11 @@
 import { startsWith } from './startsWith';
 
 import type { ChatMessageBase } from '../../components';
-import type { ChatToolMessage } from '../../components/chat/types';
+import type {
+  ChatToolMessage,
+  ClientSideTool,
+  ClientSideTools,
+} from '../../components/chat/types';
 
 export const getTextContent = (message: ChatMessageBase) => {
   return message.parts
@@ -23,4 +27,18 @@ export const isPartTool = (
   part: ChatMessageBase['parts'][number]
 ): part is ChatToolMessage => {
   return startsWith(part.type, 'tool-');
-};
\ No newline at end of file
+};
+
+export const findTool = (
+  partType: string,
+  tools: ClientSideTools
+): ClientSideTool | undefined => {
+  const toolName = partType.replace('tool-', '');
+  let tool: ClientSideTool | undefined = tools[toolName];
+  if (!tool) {
+    tool = Object.entries(tools).find(([key]) =>
+      startsWith(toolName, `${key}_`)
+    )?.[1];
+  }
+  return tool;
+};

From aed2537bd227c20305af383e34ba47b6680cf8a1 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Fri, 10 Apr 2026 01:48:44 +0100
Subject: [PATCH 20/23] remove search tool loading text

---
 packages/instantsearch.js/src/widgets/chat/chat.tsx      | 9 ---------
 .../src/widgets/chat/tools/SearchIndexTool.tsx           | 9 ---------
 2 files changed, 18 deletions(-)

diff --git a/packages/instantsearch.js/src/widgets/chat/chat.tsx b/packages/instantsearch.js/src/widgets/chat/chat.tsx
index f5be7f1ebd5..35adc789417 100644
--- a/packages/instantsearch.js/src/widgets/chat/chat.tsx
+++ b/packages/instantsearch.js/src/widgets/chat/chat.tsx
@@ -143,14 +143,6 @@ function createCarouselTool<
       );
     }, [items.length, input, output?.nbHits, applyFilters, onClose]);
 
-    if (message.state === 'input-streaming') {
-      return (
-        <div className="ais-ChatToolSearchIndex-loading">
-          Searching…
-        </div>
-      );
-    }
-
     return carousel({
       showNavigation: false,
       templates: {
@@ -265,7 +257,6 @@ function createCarouselTool<
 
   return {
     templates: { layout: SearchLayoutComponent },
-    showLoaderDuringStreaming: false,
   };
 }
 
diff --git a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
index 406de1e806e..67adad96fb7 100644
--- a/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
+++ b/packages/react-instantsearch/src/widgets/chat/tools/SearchIndexTool.tsx
@@ -93,14 +93,6 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
       );
     }, [items.length, input, output?.nbHits, applyFilters, onClose]);
 
-    if (message.state === 'input-streaming') {
-      return (
-        <div className="ais-ChatToolSearchIndex-loading">
-          Searching…
-        </div>
-      );
-    }
-
     return (
       <Carousel
         items={items}
@@ -205,7 +197,6 @@ function createCarouselTool<TObject extends RecordWithObjectID>(
 
   return {
     layoutComponent: SearchLayoutComponent,
-    showLoaderDuringStreaming: false,
   };
 }
 

From cdea719574d1fc219e00e592469e173545824fbd Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Fri, 10 Apr 2026 09:30:41 +0100
Subject: [PATCH 21/23] optionally skip json repair

---
 .../chat/__tests__/connectChat-test.ts        | 130 ++++++++++++++++++
 .../src/connectors/chat/connectChat.ts        |   8 ++
 .../src/lib/ai-lite/abstract-chat.ts          |  17 ++-
 .../instantsearch.js/src/lib/ai-lite/types.ts |   1 +
 4 files changed, 152 insertions(+), 4 deletions(-)

diff --git a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
index e75b0832e2f..0e4a9ca43d9 100644
--- a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
+++ b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
@@ -447,6 +447,7 @@ describe('connectChat', () => {
       const renderState = getRenderState();
       expect(renderState.tools).toEqual({
         testTool: {
+          showLoaderDuringStreaming: true,
           ...mockTool,
           addToolResult: expect.any(Function),
           applyFilters: expect.any(Function),
@@ -565,6 +566,135 @@ data: [DONE]`,
         expect(toolPart?.input).toEqual({});
       });
     });
+
+    it('skips JSON repair for tools with showLoaderDuringStreaming enabled (default)', async () => {
+      const { widget } = getInitializedWidget({
+        agentId: undefined,
+        tools: {
+          myTool: {},
+        },
+        transport: {
+          fetch: () =>
+            Promise.resolve(
+              new Response(
+                `data: {"type": "start", "messageId": "test-id"}
+
+data: {"type": "start-step"}
+
+data: {"type": "tool-input-start", "toolCallId": "call_1", "toolName": "myTool"}
+
+data: {"type": "tool-input-delta", "toolCallId": "call_1", "toolName": "myTool", "inputTextDelta": "{\\"query\\": \\"sho"}
+
+data: {"type": "finish-step"}
+
+data: {"type": "finish"}
+
+data: [DONE]`,
+                {
+                  headers: { 'Content-Type': 'text/event-stream' },
+                }
+              )
+            ),
+        },
+      });
+
+      const { chatInstance } = widget;
+
+      await chatInstance.sendMessage({
+        id: 'message-id',
+        role: 'user',
+        parts: [{ type: 'text', text: 'search' }],
+      });
+
+      await waitFor(() => {
+        const lastMessage =
+          chatInstance.messages[chatInstance.messages.length - 1];
+        const toolPart = lastMessage?.parts.find(
+          (part) =>
+            'type' in part &&
+            part.type === 'tool-myTool' &&
+            'toolCallId' in part &&
+            part.toolCallId === 'call_1'
+        ) as
+          | {
+              state: string;
+              rawInput?: string;
+              input?: unknown;
+            }
+          | undefined;
+
+        expect(toolPart?.state).toBe('input-streaming');
+        // Input is not repaired since showLoaderDuringStreaming defaults to true
+        expect(toolPart?.input).toBeUndefined();
+        // Raw input is still accumulated
+        expect(toolPart?.rawInput).toBe('{"query": "sho');
+      });
+    });
+
+    it('repairs JSON for tools with showLoaderDuringStreaming set to false', async () => {
+      const { widget } = getInitializedWidget({
+        agentId: undefined,
+        tools: {
+          myTool: {
+            showLoaderDuringStreaming: false,
+          },
+        },
+        transport: {
+          fetch: () =>
+            Promise.resolve(
+              new Response(
+                `data: {"type": "start", "messageId": "test-id"}
+
+data: {"type": "start-step"}
+
+data: {"type": "tool-input-start", "toolCallId": "call_1", "toolName": "myTool"}
+
+data: {"type": "tool-input-delta", "toolCallId": "call_1", "toolName": "myTool", "inputTextDelta": "{\\"query\\": \\"sho"}
+
+data: {"type": "finish-step"}
+
+data: {"type": "finish"}
+
+data: [DONE]`,
+                {
+                  headers: { 'Content-Type': 'text/event-stream' },
+                }
+              )
+            ),
+        },
+      });
+
+      const { chatInstance } = widget;
+
+      await chatInstance.sendMessage({
+        id: 'message-id',
+        role: 'user',
+        parts: [{ type: 'text', text: 'search' }],
+      });
+
+      await waitFor(() => {
+        const lastMessage =
+          chatInstance.messages[chatInstance.messages.length - 1];
+        const toolPart = lastMessage?.parts.find(
+          (part) =>
+            'type' in part &&
+            part.type === 'tool-myTool' &&
+            'toolCallId' in part &&
+            part.toolCallId === 'call_1'
+        ) as
+          | {
+              state: string;
+              rawInput?: string;
+              input?: unknown;
+            }
+          | undefined;
+
+        expect(toolPart?.state).toBe('input-streaming');
+        // Input is repaired since showLoaderDuringStreaming is false
+        expect(toolPart?.input).toEqual({ query: 'sho' });
+        expect(toolPart?.rawInput).toBe('{"query": "sho');
+      });
+    });
   });
 
   describe('transport configuration', () => {
diff --git a/packages/instantsearch.js/src/connectors/chat/connectChat.ts b/packages/instantsearch.js/src/connectors/chat/connectChat.ts
index c9c18c5c39a..250d95ba4cb 100644
--- a/packages/instantsearch.js/src/connectors/chat/connectChat.ts
+++ b/packages/instantsearch.js/src/connectors/chat/connectChat.ts
@@ -420,6 +420,14 @@ export default (function connectChat<TWidgetParams extends UnknownWidgetParams>(
         ...options,
         transport,
         sendAutomaticallyWhen: lastAssistantMessageIsCompleteWithToolCalls,
+        shouldRepairToolInput(toolName) {
+          let tool = tools[toolName];
+          if (!tool && toolName.startsWith(`${SearchIndexToolType}_`)) {
+            tool = tools[SearchIndexToolType];
+          }
+          if (!tool) return true;
+          return tool.showLoaderDuringStreaming === false;
+        },
         onToolCall({ toolCall }) {
           let tool = tools[toolCall.toolName];
 
diff --git a/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts b/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
index ff0dd4db310..4cbdb794ea1 100644
--- a/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
+++ b/packages/instantsearch.js/src/lib/ai-lite/abstract-chat.ts
@@ -132,6 +132,7 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
   private sendAutomaticallyWhen?: (options: {
     messages: TUIMessage[];
   }) => boolean | PromiseLike<boolean>;
+  private shouldRepairToolInput?: (toolName: string) => boolean;
 
   private activeResponse: ActiveResponse | null = null;
   private jobExecutor = new SerialJobExecutor();
@@ -146,6 +147,7 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
     onFinish,
     onData,
     sendAutomaticallyWhen,
+    shouldRepairToolInput,
   }: Omit<ChatInit<TUIMessage>, 'messages'> & {
     state: ChatState<TUIMessage>;
   }) {
@@ -158,6 +160,7 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
     this.onFinish = onFinish;
     this.onData = onData;
     this.sendAutomaticallyWhen = sendAutomaticallyWhen;
+    this.shouldRepairToolInput = shouldRepairToolInput;
   }
 
   /**
@@ -758,10 +761,16 @@ export abstract class AbstractChat<TUIMessage extends UIMessage> {
               const nextRawInput = `${previousRawInput}${chunk.inputTextDelta}`;
               toolRawInputByCallId[chunk.toolCallId] = nextRawInput;
 
-              const parsedInput = parseToolInputDelta(
-                nextRawInput,
-                existingPart?.input
-              );
+              const toolName =
+                chunk.toolName ??
+                existingPart?.type?.replace('tool-', '');
+              const shouldRepair =
+                toolName
+                  ? (this.shouldRepairToolInput?.(toolName) ?? true)
+                  : true;
+              const parsedInput = shouldRepair
+                ? parseToolInputDelta(nextRawInput, existingPart?.input)
+                : existingPart?.input;
 
               const nextToolPart = {
                 ...(existingPart ?? {
diff --git a/packages/instantsearch.js/src/lib/ai-lite/types.ts b/packages/instantsearch.js/src/lib/ai-lite/types.ts
index daf60dc86be..12d83e7896d 100644
--- a/packages/instantsearch.js/src/lib/ai-lite/types.ts
+++ b/packages/instantsearch.js/src/lib/ai-lite/types.ts
@@ -434,6 +434,7 @@ export interface ChatInit<UI_MESSAGE extends UIMessage> {
   sendAutomaticallyWhen?: (options: {
     messages: UI_MESSAGE[];
   }) => boolean | PromiseLike<boolean>;
+  shouldRepairToolInput?: (toolName: string) => boolean;
 }
 
 export type CreateUIMessage<UI_MESSAGE extends UIMessage> = Omit<

From e16c8c4f68619f24859be38b3f26cf9fe12cf45b Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Fri, 10 Apr 2026 09:36:21 +0100
Subject: [PATCH 22/23] update bundlesize

---
 bundlesize.config.json | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/bundlesize.config.json b/bundlesize.config.json
index 1dfc56e30ea..666b80171d4 100644
--- a/bundlesize.config.json
+++ b/bundlesize.config.json
@@ -10,11 +10,11 @@
     },
     {
       "path": "./packages/instantsearch.js/dist/instantsearch.production.min.js",
-      "maxSize": "121.8 kB"
+      "maxSize": "122.75 kB"
     },
     {
       "path": "./packages/instantsearch.js/dist/instantsearch.development.js",
-      "maxSize": "253.4 kB"
+      "maxSize": "255 kB"
     },
     {
       "path": "packages/react-instantsearch-core/dist/umd/ReactInstantSearchCore.min.js",

From 60788da133b6a8f089b43c568413c023927de058 Mon Sep 17 00:00:00 2001
From: Shahmir Ejaz <shaejaz5@gmail.com>
Date: Fri, 10 Apr 2026 09:57:34 +0100
Subject: [PATCH 23/23] rename flag

---
 .../src/components/chat/ChatMessage.tsx               |  2 +-
 .../src/components/chat/ChatMessages.tsx              |  2 +-
 .../src/components/chat/types.ts                      |  2 +-
 .../src/connectors/chat/__tests__/connectChat-test.ts | 11 +++++------
 .../src/connectors/chat/connectChat.ts                |  3 +--
 5 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
index 9ad5eb6a907..fcfc64b74a7 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessage.tsx
@@ -245,7 +245,7 @@ export function createChatMessageComponent({ createElement }: Renderer) {
 
           if (
             toolMessage.state === 'input-streaming' &&
-            tool.showLoaderDuringStreaming
+            !tool.streamInput
           ) {
             return null;
           }
diff --git a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
index 2f53483ace8..ef97805c3b0 100644
--- a/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
+++ b/packages/instantsearch-ui-components/src/components/chat/ChatMessages.tsx
@@ -520,7 +520,7 @@ const getShowLoader = (
     if (lastPart.state === 'output-available') return false;
     if (lastPart.state === 'input-streaming') {
       const tool = findTool(lastPart.type, tools);
-      return tool?.showLoaderDuringStreaming !== false;
+      return !tool?.streamInput;
     }
     return true;
   }
diff --git a/packages/instantsearch-ui-components/src/components/chat/types.ts b/packages/instantsearch-ui-components/src/components/chat/types.ts
index bdbe76e02ca..37f42e3691d 100644
--- a/packages/instantsearch-ui-components/src/components/chat/types.ts
+++ b/packages/instantsearch-ui-components/src/components/chat/types.ts
@@ -496,7 +496,7 @@ export type ClientSideToolComponent = (
 
 export type ClientSideTool = {
   layoutComponent?: ClientSideToolComponent;
-  showLoaderDuringStreaming?: boolean;
+  streamInput?: boolean;
   addToolResult: AddToolResult;
   sendEvent?: SendEventForHits;
   onToolCall?: (
diff --git a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
index 0e4a9ca43d9..aff5df16586 100644
--- a/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
+++ b/packages/instantsearch.js/src/connectors/chat/__tests__/connectChat-test.ts
@@ -447,7 +447,6 @@ describe('connectChat', () => {
       const renderState = getRenderState();
       expect(renderState.tools).toEqual({
         testTool: {
-          showLoaderDuringStreaming: true,
           ...mockTool,
           addToolResult: expect.any(Function),
           applyFilters: expect.any(Function),
@@ -567,7 +566,7 @@ data: [DONE]`,
       });
     });
 
-    it('skips JSON repair for tools with showLoaderDuringStreaming enabled (default)', async () => {
+    it('skips JSON repair for tools without streamInput (default)', async () => {
       const { widget } = getInitializedWidget({
         agentId: undefined,
         tools: {
@@ -624,19 +623,19 @@ data: [DONE]`,
           | undefined;
 
         expect(toolPart?.state).toBe('input-streaming');
-        // Input is not repaired since showLoaderDuringStreaming defaults to true
+        // Input is not repaired since streamInput is not set (default)
         expect(toolPart?.input).toBeUndefined();
         // Raw input is still accumulated
         expect(toolPart?.rawInput).toBe('{"query": "sho');
       });
     });
 
-    it('repairs JSON for tools with showLoaderDuringStreaming set to false', async () => {
+    it('repairs JSON for tools with streamInput set to true', async () => {
       const { widget } = getInitializedWidget({
         agentId: undefined,
         tools: {
           myTool: {
-            showLoaderDuringStreaming: false,
+            streamInput: true,
           },
         },
         transport: {
@@ -690,7 +689,7 @@ data: [DONE]`,
           | undefined;
 
         expect(toolPart?.state).toBe('input-streaming');
-        // Input is repaired since showLoaderDuringStreaming is false
+        // Input is repaired since streamInput is true
         expect(toolPart?.input).toEqual({ query: 'sho' });
         expect(toolPart?.rawInput).toBe('{"query": "sho');
       });
diff --git a/packages/instantsearch.js/src/connectors/chat/connectChat.ts b/packages/instantsearch.js/src/connectors/chat/connectChat.ts
index 250d95ba4cb..2e493e4c3cf 100644
--- a/packages/instantsearch.js/src/connectors/chat/connectChat.ts
+++ b/packages/instantsearch.js/src/connectors/chat/connectChat.ts
@@ -426,7 +426,7 @@ export default (function connectChat<TWidgetParams extends UnknownWidgetParams>(
             tool = tools[SearchIndexToolType];
           }
           if (!tool) return true;
-          return tool.showLoaderDuringStreaming === false;
+          return Boolean(tool.streamInput);
         },
         onToolCall({ toolCall }) {
           let tool = tools[toolCall.toolName];
@@ -607,7 +607,6 @@ export default (function connectChat<TWidgetParams extends UnknownWidgetParams>(
         const toolsWithAddToolResult: ClientSideTools = {};
         Object.entries(tools).forEach(([key, tool]) => {
           const toolWithAddToolResult: ClientSideTool = {
-            showLoaderDuringStreaming: true,
             ...tool,
             addToolResult: _chatInstance.addToolResult,
             applyFilters,