Fixed in 2.3.0

Preserved buffered books until a new page or selection is successfully extracted, preventing failed captures from deleting existing chapters.
Added unique job IDs and ownership checks so stale heartbeats or completion messages cannot interfere with newer captures.
Replaced endless popup spinners with clear errors for restricted tabs, busy jobs, missing responses, and interrupted captures.
Detected storage write failures throughout the popup and editors instead of incorrectly reporting that changes were saved.
Warned before closing the chapter editor with unsaved book, metadata, CSS, chapter, order, or removal changes.
Kept chapters with blank titles, added safe fallback titles, and focused the empty title before generation rather than silently dropping content.
Captured responsive, <picture>, srcset, and common lazy loaded images more reliably, including pages that use placeholder pixels.
Reported images omitted because downloads were blocked or their formats were unsupported, while still producing the eBook.
Rounded and validated generated SVG and image dimensions so fractional or invalid values no longer break EPUB validation.
Generated deterministic, unique chapter and stylesheet filenames, preventing collisions, overwritten chapters, and invalid manifests.
Strengthened language tag and date validation, including stored metadata from older versions, so invalid values cannot reach the EPUB package.
Restricted MathML attributes by element and normalized unsupported constructs, preventing invalid formulas from invalidating the book.
Replaced regex based CSS resource filtering with a tokenizer that handles escapes, comments, nested functions, image-set(), imports, and other disguised remote references.
Removed or repaired missing local CSS resource references, including incorrect image paths, before packaging the EPUB.
Avoided creating an empty images/ directory in text only books, eliminating the associated EPUBCheck warning.
Rejected overly long or potentially catastrophic style library regular expressions so matching cannot freeze the extension.
Removed dead helper code and implicit global XPath utilities that could throw or leak state.
Expanded automated coverage for capture failures, popup recovery, editor persistence, sanitization, image handling, stylesheet safety, and warning free EPUBCheck output.

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