The Agent Skills Directory

[INDIRECT_PROMPT_INJECTION]: The skill is designed to process and display external PDF documents which constitutes an attack surface for indirect prompt injection.
Ingestion points: The skill uses PDFDocument(url:) and PDFDocument(data:) in references/core-implementation.md to load content from external sources.
Capability inventory: In references/pdf-viewing-and-annotations.md, the ManagedPDFView coordinator implements a link handling delegate that calls UIApplication.shared.open(url). This allows the agent/application to navigate to arbitrary external websites if a link within a PDF is triggered. Additionally, the skill provides capabilities for file system writes via document.write(to:).
Boundary markers: There are no specific instructions or delimiters provided to the agent to treat embedded PDF content or links as untrusted.
Sanitization: The provided implementation does not include logic for sanitizing or validating URLs before they are passed to the system's URL opener.
[EXTERNAL_DOWNLOADS]: The skill references documentation hosted on a non-standard domain.
Evidence: Multiple links in SKILL.md point to https://sosumi.ai/documentation/pdfkit and related paths. While presented as documentation for the framework, this domain is not an official Apple developer resource and is not part of the trusted vendor list.

pdfkit