2026-03-10 Session Log

PDF Viewer UX & Page Text Extraction

Replaced image-based page context with trigger-based text extraction — cheaper, faster, and more reliable

What I Did

• Scroll animation fix — changed scrollIntoView({ behavior: "smooth" }) to "instant" to prevent janky animation when switching pages. Reduced ignoreScrollRef timeout to 100ms
• Floating toolbar fix — the bottom toolbar was scrolling away with content. Restructured the DOM: moved toolbar and search panel JSX outside the scrollable div (as siblings of scrollRef, children of containerRef)
• PdfViewerHandle with forwardRef — exposed getPageText() (using pdf.js getTextContent()) and hasFile() via imperative ref, so the parent component can extract page text on demand without owning pdf.js state
• Removed auto canvas capture — deleted the old onRenderSuccess → canvas.toDataURL() → onPageImageChange pipeline that captured a base64 image on every page render. Replaced with a lightweight onPageChange(pageNumber) callback
• Backend text endpoint — GET /api/pdfs/{pdf_id}/page/{page_num}/text using PyMuPDF get_text() (ready for when server-stored PDFs are needed)
• Page text injection — useChat detects “이 페이지” regex in user messages → calls getPageText() → sends as page_text in the POST body. Backend injects the text before the user message in Claude’s context
• Context indicator — InputBar shows “PDF 연결됨” with a tooltip explaining that mentioning “이 페이지” activates page context

Key Decisions

• Client-side extraction over server round-trip — PdfViewer already has the pdf.js document loaded in memory via pdfDocRef. Using getTextContent() client-side avoids a network request and works with locally-stored PDFs
• Trigger-based over auto-send — sending page images on every page turn was expensive (vision tokens per render). The “이 페이지” trigger costs nothing until the user explicitly references the page
• forwardRef + useImperativeHandle — correct React pattern for imperative access to child component internals without lifting pdf.js state up to the parent