streaming: collapse EventStreamClient fan-out

[TirmanSidhu]

Summary

• Replaces broadcaster subscribe(filter:) with typed per-domain dispatchers (chat / conversation list / surface / store / etc.).
• Removes startMessageLoop, messageLoopTask, messageLoopGeneration, ensureMessageLoopStarted from ChatViewModel.
• Each consumer subscribes to events by type, not by filter. SSE loop runs for the connection lifetime; routing is downstream.
• Eliminates the double-subscriber window during loop restart (one of the three root failure modes of the duplication bug).

Part of plan: streaming-message-architecture.md (PR 5 of 6)

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Do not drop incremental chat stream events

When a chat subscriber falls more than 256 events behind (for example during a long response while the main actor is busy), .bufferingNewest silently discards the oldest unread ServerMessages. Several routed chat events such as assistantTextDelta, toolInputDelta, and toolOutputChunk are incremental rather than replace-by-latest snapshots, so losing an older chunk permanently truncates the transcript/tool input until a separate history reload happens. The previous unbounded stream did not drop these deltas, so chat streaming needs a lossless path or category-specific buffering for incremental events.

Useful? React with 👍 / 👎.

[chatgpt-codex-connector]

Route AppDelegate events to appDelegate subscribers

After the fan-out split, AppDelegate+ConnectionSetup.startEventSubscription() only reads subscribeAppDelegateEvents(), but this mapping sends confirmationRequest and conversationError only to .chat. That means the AppDelegate cases that auto-approve CU confirmations / show confirmation notifications and handle managed-assistant auth errors no longer run for those events. Include these AppDelegate-handled event types in the .appDelegate category as well as chat.

Useful? React with 👍 / 👎.