PDF export freezes the app on large stories (Linux AppImage, 3.2.0)

[Wavesonics]

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Summary

Exporting a large story to PDF causes an immediate, permanent UI freeze on the Linux desktop client (AppImage). The same story exports fine to other formats. Reproduced consistently during 3.2.0 testing.

Environment

• Version: Hammer 3.2.0 (AppImage)
• OS: Linux Mint 22.3 (GNOME 46.0)
• Sync: Local self-hosted sync server over HTTP (issue reproduces with sync both off and on)

Steps to reproduce

1. Open a large story (testing used a 147k-word project).
2. Attempt to export as PDF.

Actual behavior

• First attempt produced an "unknown error" popup, then froze permanently.
• Subsequent attempts froze immediately with no popup.
• The window became completely unresponsive and could not be interacted with or moved.
• No obvious CPU spike was observed.
• Reproduces whether or not the sync server is running. The server itself remained stable throughout.

Closing the frozen app

• Normal close actions did not work.
• kill <PID> removed the process from System Monitor but did not close the frozen window.
• pkill -f hammer.AppImage reliably closed the application every time.

Expected behavior

PDF export completes (or fails gracefully with an error), without freezing the UI.

Notes

• The same story exported successfully as .md and .epub with no issues, so this appears specific to the PDF export path.
• Reported during 3.2.0 testing; PDF export was the only major issue reproducible consistently. Import stability and scene-tree drag/drop responsiveness were noted as significantly improved over 3.1.3.
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