[Obs AI Assistant] Fix auto-generation of titles (#182923)

If the LLM doesn't send the title_conversation in a single go,
`getGeneratedTitle` fails, because it doesn't wait until the message has
been fully completed. This PR fixes that issue, and adds tests, and also
improves quote matching.

x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/operators/get_generated_title.test.ts

@@ -0,0 +1,215 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+import { filter, lastValueFrom, of, throwError, toArray } from 'rxjs';
+import {
+  ChatCompletionChunkEvent,
+  Message,
+  MessageRole,
+  StreamingChatResponseEventType,
+} from '../../../../common';
+import { ChatEvent } from '../../../../common/conversation_complete';
+import { getGeneratedTitle } from './get_generated_title';
+
+describe('getGeneratedTitle', () => {
+  const messages: Message[] = [
+    {
+      '@timestamp': new Date().toISOString(),
+      message: {
+        content: 'A message',
+        role: MessageRole.User,
+      },
+    },
+  ];
+
+  function createChatCompletionChunk(
+    content: string | { content?: string; function_call?: { name: string; arguments: string } }
+  ): ChatCompletionChunkEvent {
+    const msg = typeof content === 'string' ? { content } : content;
+
+    return {
+      type: StreamingChatResponseEventType.ChatCompletionChunk,
+      id: 'id',
+      message: msg,
+    };
+  }
+
+  function callGenerateTitle(
+    ...rest: [ChatEvent[]] | [{ responseLanguage?: string }, ChatEvent[]]
+  ) {
+    const options = rest.length === 1 ? {} : rest[0];
+    const chunks = rest.length === 1 ? rest[0] : rest[1];
+
+    const chatSpy = jest.fn().mockImplementation(() => of(...chunks));
+
+    const title$ = getGeneratedTitle({
+      chat: chatSpy,
+      logger: {
+        debug: jest.fn(),
+        error: jest.fn(),
+      },
+      messages,
+      ...options,
+    });
+
+    return { chatSpy, title$ };
+  }
+
+  it('returns the given title as a string', async () => {
+    const { title$ } = callGenerateTitle([
+      createChatCompletionChunk({
+        function_call: {
+          name: 'title_conversation',
+          arguments: JSON.stringify({ title: 'My title' }),
+        },
+      }),
+    ]);
+
+    const title = await lastValueFrom(
+      title$.pipe(filter((event): event is string => typeof event === 'string'))
+    );
+
+    expect(title).toEqual('My title');
+  });
+
+  it('calls chat with the user message', async () => {
+    const { chatSpy, title$ } = callGenerateTitle([
+      createChatCompletionChunk({
+        function_call: {
+          name: 'title_conversation',
+          arguments: JSON.stringify({ title: 'My title' }),
+        },
+      }),
+    ]);
+
+    await lastValueFrom(title$);
+
+    const [name, params] = chatSpy.mock.calls[0];
+
+    expect(name).toEqual('generate_title');
+    expect(params.messages.length).toBe(2);
+    expect(params.messages[1].message.content).toContain('A message');
+  });
+
+  it('strips quotes from the title', async () => {
+    async function testTitle(title: string) {
+      const { title$ } = callGenerateTitle([
+        createChatCompletionChunk({
+          function_call: {
+            name: 'title_conversation',
+            arguments: JSON.stringify({ title }),
+          },
+        }),
+      ]);
+
+      return await lastValueFrom(
+        title$.pipe(filter((event): event is string => typeof event === 'string'))
+      );
+    }
+
+    expect(await testTitle(`"My title"`)).toEqual('My title');
+    expect(await testTitle(`'My title'`)).toEqual('My title');
+    expect(await testTitle(`"User's request for a title"`)).toEqual(`User's request for a title`);
+  });
+
+  it('mentions the given response language in the instruction', async () => {
+    const { chatSpy, title$ } = callGenerateTitle(
+      {
+        responseLanguage: 'Orcish',
+      },
+      [
+        createChatCompletionChunk({
+          function_call: {
+            name: 'title_conversation',
+            arguments: JSON.stringify({ title: 'My title' }),
+          },
+        }),
+      ]
+    );
+
+    await lastValueFrom(title$);
+
+    const [, params] = chatSpy.mock.calls[0];
+    expect(params.messages[0].message.content).toContain('Orcish');
+  });
+
+  it('handles partial updates', async () => {
+    const { title$ } = callGenerateTitle([
+      createChatCompletionChunk({
+        function_call: {
+          name: 'title_conversation',
+          arguments: '',
+        },
+      }),
+      createChatCompletionChunk({
+        function_call: {
+          name: '',
+          arguments: JSON.stringify({ title: 'My title' }),
+        },
+      }),
+    ]);
+
+    const title = await lastValueFrom(title$);
+
+    expect(title).toEqual('My title');
+  });
+
+  it('ignores token count events and still passes them through', async () => {
+    const { title$ } = callGenerateTitle([
+      createChatCompletionChunk({
+        function_call: {
+          name: 'title_conversation',
+          arguments: JSON.stringify({ title: 'My title' }),
+        },
+      }),
+      {
+        type: StreamingChatResponseEventType.TokenCount,
+        tokens: {
+          completion: 10,
+          prompt: 10,
+          total: 10,
+        },
+      },
+    ]);
+
+    const events = await lastValueFrom(title$.pipe(toArray()));
+
+    expect(events).toEqual([
+      'My title',
+      {
+        tokens: {
+          completion: 10,
+          prompt: 10,
+          total: 10,
+        },
+        type: StreamingChatResponseEventType.TokenCount,
+      },
+    ]);
+  });
+
+  it('handles errors in chat and falls back to the default title', async () => {
+    const chatSpy = jest
+      .fn()
+      .mockImplementation(() => throwError(() => new Error('Error generating title')));
+
+    const logger = {
+      debug: jest.fn(),
+      error: jest.fn(),
+    };
+
+    const title$ = getGeneratedTitle({
+      chat: chatSpy,
+      logger,
+      messages,
+    });
+
+    const title = await lastValueFrom(title$);
+
+    expect(title).toEqual('New conversation');
+
+    expect(logger.error).toHaveBeenCalledWith('Error generating title');
+  });
+});

x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/operators/get_generated_title.ts

@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { catchError, map, Observable, of, tap } from 'rxjs';
+import { catchError, last, map, Observable, of, tap } from 'rxjs';
 import { Logger } from '@kbn/logging';
 import type { ObservabilityAIAssistantClient } from '..';
 import { Message, MessageRole } from '../../../../common';
@@ -30,7 +30,7 @@ export function getGeneratedTitle({
   responseLanguage?: string;
   messages: Message[];
   chat: ChatFunctionWithoutConnectorAndTokenCount;
-  logger: Logger;
+  logger: Pick<Logger, 'debug' | 'error'>;
 }): Observable<string | TokenCountEvent> {
   return hideTokenCountEvents((hide) =>
     chat('generate_title', {
@@ -46,9 +46,11 @@ export function getGeneratedTitle({
           '@timestamp': new Date().toISOString(),
           message: {
             role: MessageRole.User,
-            content: messages.slice(1).reduce((acc, curr) => {
-              return `${acc} ${curr.message.role}: ${curr.message.content}`;
-            }, 'Generate a title, using the title_conversation_function, based on the following conversation:\n\n'),
+            content: messages
+              .filter((msg) => msg.message.role !== MessageRole.System)
+              .reduce((acc, curr) => {
+                return `${acc} ${curr.message.role}: ${curr.message.content}`;
+              }, 'Generate a title, using the title_conversation_function, based on the following conversation:\n\n'),
           },
         },
       ],
@@ -72,21 +74,21 @@ export function getGeneratedTitle({
     }).pipe(
       hide(),
       concatenateChatCompletionChunks(),
+      last(),
       map((concatenatedMessage) => {
-        const input =
+        const title: string =
           (concatenatedMessage.message.function_call.name
             ? JSON.parse(concatenatedMessage.message.function_call.arguments).title
             : concatenatedMessage.message?.content) || '';
 
-        // This regular expression captures a string enclosed in single or double quotes.
+        // This captures a string enclosed in single or double quotes.
         // It extracts the string content without the quotes.
         // Example matches:
         // - "Hello, World!" => Captures: Hello, World!
         // - 'Another Example' => Captures: Another Example
         // - JustTextWithoutQuotes => Captures: JustTextWithoutQuotes
-        const match = input.match(/^["']?([^"']+)["']?$/);
-        const title = match ? match[1] : input;
-        return title;
+
+        return title.replace(/^"(.*)"$/g, '$1').replace(/^'(.*)'$/g, '$1');
       }),
       tap((event) => {
         if (typeof event === 'string') {