How does Pointfold turn Markdown into a reader?

Pointfold separates source structure, rendering, and browser interactions.
- outline.go parses and validates a tree of points.
- render.go turns that tree into HTML with embedded assets.
- web/reader.js handles copying, navigation, and global expansion controls.
The CLI validates input before replacing an output file.
- run reads a path or standard input.
- parseOutline produces the point model [3] or an error.
- renderOutline builds the entire HTML result in memory.
- atomicWrite writes a temporary file before renaming it over the destination.
  - This sequence prevents a parsing failure from truncating an existing output.
  - A path check also prevents overwriting the input through the same path or a filesystem alias.
Every point has one text field and a list of child points.
- Text holds the point's Markdown.
- StableID holds optional source identity.
- Number holds a position such as 2.1.3 in this document version.
- Line points back to the source file for diagnostics and the refs command.
- Children holds points with the same structure.
- Markdown retains the point's own source text and visual blocks for copying without its children.
- Content holds visual blocks that appear when the point is expanded.
Parsing builds the tree before checking its cross-references.
- Goldmark parses the Markdown into a syntax tree.
- parseList collects points and rejects unsupported block structures.
- A trailing {#stable-id} is removed from point text and registered in ByID.
- A second pass rejects fragment links whose targets were never registered.
  - Waiting until the second pass permits a point to refer to a later point.
  - Duplicate stable IDs fail before link resolution can become ambiguous.
Rendering keeps stable identity separate from visible position.
- linkRenderer resolves a source link through ByID.
- The generated link points to the target's current numbered HTML anchor.
- Its label gains the target's current outline number.
- A copy button exposes that outline number without exposing the source ID.
Browser navigation reveals a target by opening only its ancestors.
- The click handler records the source point for the return button.
- reveal walks from the target toward the document root.
  - Every ancestor details element is opened.
  - The target's own children retain their previous expansion state.
- The target is highlighted and receives focus.
A moved point retains its source identity when its stable ID is preserved.
- Re-rendering updates links to its new number through reference resolution [4].
- A previously copied outline number still belongs to the older document version.
- An agent should inspect the current source or the refs output before acting on a reference from another version.