feat: implement PDF annotation extraction and inspector API endpoints via C++ bindings

bindings/python/pdfengine_py.cpp

@@ -341,6 +341,7 @@ PYBIND11_MODULE(pdfengine, m) {
         .def_readonly("content", &pdfengine::PdfPage::AnnotationInfo::content)
         .def_readonly("timestamp", &pdfengine::PdfPage::AnnotationInfo::timestamp)
         .def_readonly("page_index", &pdfengine::PdfPage::AnnotationInfo::pageIndex)
+        .def_readonly("thickness", &pdfengine::PdfPage::AnnotationInfo::thickness)
         .def_readonly("paths", &pdfengine::PdfPage::AnnotationInfo::paths)
         .def_readonly("field_name", &pdfengine::PdfPage::AnnotationInfo::fieldName)
         .def_readonly("field_value", &pdfengine::PdfPage::AnnotationInfo::fieldValue)

engine/include/pdfengine/pdf_document.hpp

@@ -198,6 +198,7 @@ public:
         std::string content;
         std::string timestamp;
         int pageIndex = 0;
+        double thickness = 0.0;
         std::vector<std::vector<Point2D>> paths;
         std::vector<std::array<Point2D, 4>> quadPoints;
 

engine/src/parser/pdfium_edit_annotations.cpp

@@ -384,6 +384,10 @@ std::expected<void, EngineError> PdfiumDocument::applyOp_freehand(const nlohmann
                 float thickness = static_cast<float>(data.value("thickness", 2.0));
                 FPDFAnnot_SetBorder(annot, 0.0f, 0.0f, thickness);
 
+                std::string tStr = std::to_string(thickness);
+                auto tUtf16 = utf8_to_utf16le(tStr);
+                FPDFAnnot_SetStringValue(annot, "CustomThickness", reinterpret_cast<FPDF_WIDESTRING>(tUtf16.data()));
+
                 float minX = 1e9f, minY = 1e9f, maxX = -1e9f, maxY = -1e9f;
                 bool anyPoints = false;
 
@@ -550,6 +554,10 @@ std::expected<void, EngineError> PdfiumDocument::applyOp_updateAnnotation(const
                     if (data.contains("thickness")) {
                         float thickness = static_cast<float>(data["thickness"].get<double>());
                         FPDFAnnot_SetBorder(targetAnnot, 0.0f, 0.0f, thickness);
+
+                        std::string tStr = std::to_string(thickness);
+                        auto tUtf16 = utf8_to_utf16le(tStr);
+                        FPDFAnnot_SetStringValue(targetAnnot, "CustomThickness", reinterpret_cast<FPDF_WIDESTRING>(tUtf16.data()));
                     }
 
                     if (data.contains("text")) {

engine/src/parser/pdfium_page_model.cpp

@@ -600,6 +600,21 @@ std::expected<std::vector<PdfPage::AnnotationInfo>, EngineError> PdfiumPage::ext
             }
 
             if (subtype == FPDF_ANNOT_INK) {
+                float h_radius = 0, v_radius = 0, border_width = 1.0f;
+                info.thickness = 2.0; // default
+
+                unsigned long ctLen = FPDFAnnot_GetStringValue(annot, "CustomThickness", nullptr, 0);
+                if (ctLen > 2) {
+                    std::vector<char16_t> ctBuf(ctLen / 2);
+                    FPDFAnnot_GetStringValue(annot, "CustomThickness", reinterpret_cast<FPDF_WCHAR*>(ctBuf.data()), ctLen);
+                    std::string ctStr = utf16le_to_utf8(ctBuf.data(), ctBuf.size());
+                    try {
+                        info.thickness = std::stod(ctStr);
+                    } catch (...) {}
+                } else if (FPDFAnnot_GetBorder(annot, &h_radius, &v_radius, &border_width)) {
+                    info.thickness = border_width;
+                }
+                
                 const double pageH = height();
                 unsigned long strokeCount = FPDFAnnot_GetInkListCount(annot);
                 for (unsigned long s = 0; s < strokeCount; ++s) {

frontend/src/components/InspectorPanel.tsx

@@ -208,7 +208,7 @@ const NotesTab: React.FC<{ annotations: Annotation[]; onNavigate: (a: Annotation
             <span className="text-[10px] font-medium text-[#98a1ad]">{a.author}</span>
           </CustomButton>
           
-          {onUpdate && (a.type === 'highlight' || a.type === 'ink' || a.type === 'comment') && (
+          {onUpdate && (['highlight', 'ink', 'comment', 'strikeout', 'underline', 'squiggly'].includes(a.type)) && (
             <div className="flex items-center gap-2 mt-1 px-1" onClick={e => e.stopPropagation()}>
               <input
                 type="color"

gateway/app/routers/documents/content.py

@@ -111,6 +111,7 @@ def get_document_annotations(document_id: str) -> list[AnnotationResponse]:
                         content=a.content,
                         timestamp=getattr(a, "timestamp", None),
                         pageIndex=a.page_index,
+                        thickness=getattr(a, "thickness", None),
                         paths=[[{"x": p.x, "y": p.y} for p in stroke] for stroke in getattr(a, "paths", [])],
                         quadPoints=getattr(a, "quad_points", []),
                         fieldName=getattr(a, "field_name", None),

gateway/app/schemas/annotation.py

@@ -13,6 +13,7 @@ class AnnotationResponse(BaseModel):
     content: str
     timestamp: str | None = None
     pageIndex: int
+    thickness: float | None = None
     paths: list[list[dict[str, float]]] = []
     quadPoints: list[list[dict[str, float]]] = []