Add UI button to convert PDF files to EPUB format

[Copilot]

• Add Convert to EPUB button for PDF-only media items
• Fix read-only filesystem error in serverless environment
  • Configured EPub library to use /tmp directory for temporary files
  • This prevents EROFS errors in Vercel's read-only filesystem
• Fix ENOENT error for missing CSS template files
  • Added inline CSS to EPub options to avoid dependency on external template files
  • Prevents "no such file or directory" errors for template.css

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Project	Deployment	Review	Updated (UTC)
secret-library	Ready	Preview, Comment	Dec 19, 2025 6:54pm

[andrepetsch]

@copilot Please add a button to trigger the conversion on media, that only has a pdf file.

[Copilot]

@copilot Please add a button to trigger the conversion on media, that only has a pdf file.

Added a "Convert to EPUB" button in commit d2948f7. The button:

• Only appears for media items with a single PDF file (no EPUB yet)
• Only visible to the media owner (same permissions as Edit/Delete)
• Shows "Converting..." state while processing
• Appears as a full-width indigo button below the Edit/Delete row
• Calls /api/media/convert-pdf-to-epub with the media ID
• Refreshes the media list after successful conversion

The button will be displayed on library cards that have only a PDF file, making it easy to convert them to EPUB format with one click.

[andrepetsch]

@copilot The Button is good, but I'm now getting this error:

    at sM.render (.next/server/chunks/[root-of-the-server]__414d0d4e._.js:7:294147)
    at sj (.next/server/chunks/[root-of-the-server]__414d0d4e._.js:19:4127)
    at async sz (.next/server/chunks/[root-of-the-server]__414d0d4e._.js:33:1978)
    at async sW (.next/server/chunks/[root-of-the-server]__414d0d4e._.js:33:500)
    at async m (.next/server/chunks/[root-of-the-server]__414d0d4e._.js:33:5733)
    at async o (.next/server/chunks/[root-of-the-server]__414d0d4e._.js:33:6779) {
  errno: -30,
  code: 'EROFS',
  syscall: 'mkdir',
  path: '/var/task/.next/server/assets/tempDir'
}

Please check if the file is not stored anywhere else then the blob storage.

[Copilot]

@copilot The Button is good, but I'm now getting this error:

    at sM.render (.ne...

Fixed the read-only filesystem error in commit 714d2f1.

The issue was that the @lesjoursfr/html-to-epub library was creating temporary directories in a read-only location. I added tempDir: '/tmp' to the EPub configuration to force all temporary files to use /tmp, which is writable in serverless environments.

All files are now:

• Temporarily written to /tmp during conversion
• Uploaded to Vercel Blob storage (no local storage)
• Cleaned up after conversion completes

The conversion should now work correctly in your Vercel deployment.

[andrepetsch]

@copilot Please have a look at this error:

[Copilot]

@copilot Please have a look at this error:

Fixed the ENOENT error in commit 6f8c77b.

The issue was that the @lesjoursfr/html-to-epub library was trying to access CSS template files that don't exist in the build output. I added inline CSS directly to the EPub options using the css property, which provides the styling without requiring external template files.

The EPUB files will now be generated with clean, readable formatting using a serif font and proper spacing.