Annotation robustness and review modes

Provenance stamp: This issue was triaged on June 13, 2026 as part of the older-than-two-month GitHub issue triage exercise.

Source issues: #216, #311, #357

## Summary

Annotation quality matters most when the reviewed document is long or shared. These issues all ask for a stronger annotation model: restore highlights reliably, let users fix selections, and provide better ways to review all markup at once.

## What the source issues requested

- #216 reported that cross-block annotation highlights were not restored from shared URLs or drafts because restoration fell back to text search across rendered block boundaries.
- #311 requested overview mode and inline annotation display so reviewers can scan long plans, see annotation density, and read comments in context without clicking each highlight.
- #357 requested the ability to edit the selected text range for a comment and to scroll to the comment when editing.

## Triage determination

These should be tracked together because they all depend on annotation anchoring, navigation, and display modes. A reliable restore path is the foundation. Overview and inline markup are the review modes that make the annotation model useful at scale.

## Acceptance criteria

- Cross-block annotations restore reliably from shared URLs and drafts.
- Share and draft payloads preserve enough anchoring metadata to avoid text-search-only restoration where possible.
- Editing an annotation can adjust the selected range.
- Editing or selecting an annotation scrolls to the relevant document location.
- Long-document overview or minimap shows annotation density by section.
- Inline all-markup mode renders comment text in the document flow for scanning and sharing.
- The old source issues can be closed once these annotation robustness and review-mode requirements are represented here.