Margin model flaws (user feedback): fragment placement needs unreliable
routing; scattering kills the receipt moment and chronology; session
value is in the moment, revision is rare, HTML export deprioritized.
Evolved model: one chronological spine; learner blocks are intact typed
'interjection' cards; teacher replies as woven Q&A interludes
(quote-then-answer); anchoring is a link overlay (backlinks), margins
demoted to a computed view. Chat-ness dies by type asymmetry, not
relocation.
Asymmetry of artifact: the teacher writes the document (whiteboard), the
learner writes in the margins (voice/floor). Bubbles die; the unit is the
block; chronology yields to tree structure; Q&A becomes document
furniture; the composer becomes a response field. Presentation-layer
change only — the interaction model stays conversational.
Captures 2026-08-22 decisions: hybrid live-emission + consolidation graph
construction (reversing the vault doc's teacher-untouched rule), one
substrate merged across sessions, structured plan-tree tools (mermaid
demoted to ad-hoc), probe/teach phase separation with collapsed teach
checks, right-panel tree view, LaTeX delimiter switch plan, and a
dependency-ordered roadmap.