Add chat log subscription endpoint

[balloob]

Breaking change

Proposed change

To improve debugging of LLMs, adding a set of endpoints to allow voice assistant debug sessions to look inside the chat log data to see what was sent between LLM and HA.

Frontend: home-assistant/frontend#27678

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• This PR fixes or closes issue: fixes #
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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (homeassistant) you are listed as a code owner for? Thanks!

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[home-assistant]

Hey there @home-assistant/core, @synesthesiam, @arturpragacz, mind taking a look at this pull request as it has been labeled with an integration (conversation) you are listed as a code owner for? Thanks!

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[Copilot]

Pull Request Overview

This PR adds WebSocket subscription endpoints for chat log monitoring to improve debugging of LLM interactions in voice assistant sessions. The implementation allows real-time observation of conversation data exchanged between LLMs and Home Assistant.

Key changes:

• Added two WebSocket subscription endpoints for chat log access: individual conversation and index (all conversations)
• Implemented event notification system for chat log lifecycle (created, updated, deleted, content_added)
• Added as_dict() serialization methods and timestamp tracking to content models

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
homeassistant/components/conversation/http.py	Implements WebSocket subscription handlers for chat logs
homeassistant/components/conversation/chat_log.py	Adds event subscription infrastructure and serialization methods
homeassistant/components/conversation/const.py	Defines chat log event type enumeration
homeassistant/components/homeassistant/const.py	Fixes typo in exposed entities key name
tests/components/conversation/test_http.py	Tests WebSocket subscription endpoints and event flows
tests/components/conversation/test_chat_log.py	Tests chat log subscription and event notification system

[arturpragacz]

I'm not a fan of the fact that this adds yet another mechanism to report events related to voice.

[balloob]

@arturpragacz I hear you, however, chat log is not voice specific. It's the way we track the history of an interaction with an AI from either conversation or AI task. If we were to add these events into the Assist Pipeline websocket endpoint, we would now need to also make that one aware of AI task. Would you have another suggestion?

[arturpragacz]

I hear you, however, chat log is not voice specific. It's the way we track the history of an interaction with an AI from either conversation or AI task. If we were to add these events into the Assist Pipeline websocket endpoint, we would now need to also make that one aware of AI task. Would you have another suggestion?

Can we not have a way to register a callback in the chat log, which can then be used in the higher layer. So the assist pipeline would use it to provide those events through its websocket and the AI task could do what is the best for it. I don't think we have any debug interface for AI tasks at this point anyway, unless I'm missing something.

[balloob]

This is the debugging endpoint for AI tasks.

[arturpragacz]

Please address the open comments by Copilot.

[arturpragacz]

As discussed, let's merge it now, but investigate how to include conversation trace in this.