Desktop (macOS): reopening an existing conversation shows a blank transcript (history not rendered), though context is retained

**Describe the bug**
After closing and reopening the Claude Code desktop app (for example, the next day), opening the **same existing conversation** displays a completely **blank message panel** — none of the previous messages are rendered. The transcript looks empty/lost in the UI.

However, there is **no actual data loss**: when I ask Claude within that same conversation, it still remembers the full prior discussion correctly. So the history clearly still exists on the backend, it is just **not displayed** after reopening.

**Steps to reproduce**
1. Have a normal conversation in the Claude Code desktop app (macOS).
2. Close the app / leave it until the next day.
3. Reopen the app and open the **same** conversation.
4. The conversation panel is blank — no message history is rendered.
5. Ask a question in that conversation; Claude still recalls the earlier context, confirming the data is present but not shown.

**Expected behavior**
Reopening the conversation shows its full previous message history.

**Actual behavior**
The reopened conversation shows a blank/empty transcript; the message history is not rendered, even though the context is clearly retained (Claude still remembers it).

**Environment**
- Claude Code desktop app
- OS: macOS (Darwin 25.5.0)
- Model: Opus 4.8
- App version: (please fill in — Settings/About)

**Additional context**
This appears to be a transcript loading/rendering issue on reopening a conversation, not data loss. Restarting the app / reopening does not restore the visible history.

No source file or test is named. Start by reproducing the issue in the Claude Code desktop app on macOS, then trace the existing-conversation loading and transcript-rendering entry points. Done means reopening a conversation displays its complete prior message history while retaining the existing context.

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