[5.7] Deep-linking + section anchoring in resource viewer

[jasminetay-moe]

Epic: Part 5 — Native Resource Viewer
Sprint: Sprint 6
Priority: P2
Role: Engineer

User Story

As an Engineer, I want to implement deep-linking and section-level anchoring so that when a teacher opens a document from a citation, they land directly on the cited passage.

Context

When a teacher taps a source citation in a recommendation card or AI Chat response, the viewer should open the document at the exact referenced section — not the document start. This is citation-triggered only; documents opened from the resources tab just open normally (handled in 5.6).

The LLM response must include a section reference or anchor in the citation metadata for this to work — this needs to be agreed as part of the RAG output format.

Acceptance Criteria

• Citation link includes section reference / anchor metadata from the LLM response
• Viewer opens document at the cited section when triggered from a card or AI Chat citation
• Falls back gracefully to document start if no anchor metadata is present
• Section anchoring works for supported formats (PDF page anchor, HTML id anchor)

Dependencies

• Blocked by: [5.6] Implement inline document viewer in TW #41 (5.6) — native document viewer must exist first
• Requires: LLM output format includes citation anchor metadata (coordinate with Part 1 / 1.11)

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📄 PRD: Part 5 — Glow CI PRD