Capture the design decisions reached while grilling the core-parser spec: - Parser is a total function; invalid frontmatter YAML surfaces through a new Document AST `diagnostics` channel instead of throwing (ADR 0004). - Parse all of OFM losslessly via `RawBlock`/`RawInline` fallbacks with position-sliced verbatim source and a minimal plugin set (ADR 0005). - Grammar-driven (not last-space) quantity/unit split, fixing the mixed-number collision, with trimming and multi-word unit rules. - Container blocks nest `Block[]` so annotations surface inside blockquotes and list items; unified wikilink/transclusion shape. Update SPEC.md and CONTEXT.md accordingly; no parser code yet.