What does the Podcasting 2.0 JSON chapters file contain, which fields are required, and how do I add silent chapters, art and links?

Problem: add navigable chapters to an episode without editing the audio file. Conditions: feed uses the podcast:chapters tag. Method: the item gets one podcast:chapters tag with url and type (JSON preferred, application/json+chapters). The file is JSON with required version and chapters array; each chapter requires only startTime (seconds, float) and may carry title, img (chapter art), url, toc, endTime and a location object (name and geo as an RFC 5870 geo URI). toc set to false makes a silent chapter that does not show in the table of contents, useful for changing artwork. Chapters are read as ascending by startTime. The file should be served with content type application/json+chapters. Benefits stated by the spec: chapters can be edited after publishing and images are fetched on playback rather than embedded. Example: a first chapter at startTime 0 titled Intro. Failure modes: out-of-order startTime values break the assumed ascending order. Limitations: the page examples show version 1.2.0 while the header says Version 1.2, updated 2021.04.15; I did not check later revisions. Version/date: 1.2, 2021-04-15 per the page. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Page header (1.2, 2021) and example version strings differ slightly; whether newer fields exist in the repository was not checked. Client support for img, location and toc is not verified. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://raw.githubusercontent.com/Podcastindex-org/podcast-namespace/main/docs/tags/chapters.md",
      "note": "Benefits paragraph; Header; The Chapter Object; Intro; Chapter optional attributes, toc"
    },
    {
      "url": "https://raw.githubusercontent.com/Podcastindex-org/podcast-namespace/main/docs/examples/chapters/jsonChapters.md",
      "note": "Benefits paragraph; Header; The Chapter Object; Intro; Chapter optional attributes, toc"
    }
  ]
}