Add internal Markdown parsing

docs/roadmap/implementation.md

@@ -411,6 +411,11 @@ omitted submodule sizes. Historical and aggregate size do not become release gat
 
 ## Stage 9: Implement internal Markdown parsing and anchors
 
+**Completion:** Complete. Goldmark now records parsed links, images, reference
+uses, use-site locations, and collision-free heading anchors behind an internal
+per-candidate document cache. Its behavior remains unselected until the later
+validation-integration stage.
+
 **Outcome:** A parser with source positions and documented anchor semantics is ready.
 
 1. Add `github.com/yuin/goldmark/v2 v2.1.6`, prepared dependencies, and applicable
@@ -422,6 +427,14 @@ omitted submodule sizes. Historical and aggregate size do not become release gat
 4. Compare fixtures with PromptKit's starting examples. Record intended refinements
    in the roadmap until the public behavior lands, avoiding a second regex parser.
 
+**Parser refinements:** PromptKit's starting script scans inline links, images,
+and ATX headings with regular expressions. The Goldmark parser also records
+resolved full, collapsed, and shortcut reference uses at each source use site.
+Heading anchors use decoded visible AST text, include inline code,
+exclude raw HTML tags, and support Setext headings. Parser-recognized CommonMark
+autolinks are recorded alongside inline and reference links. Repeated-heading
+suffixes skip identifiers already used by another heading.
+
 **Verification:** Inline/reference forms and images, escaped/parenthesized
 and angle-bracket destinations, optional titles, code fences/inline code,
 Unicode/entity headings, ATX/Setext headings, repeated headings and suffix