# Session 0020.0 — Transcript

> App: vscode-cowriting-plugin
> Start: 2026-06-11T08-19 (PST)
> End: 2026-06-11T08-29 (PST)
> Type: brainstorming
> Status: **FINALIZED**

## Launch prompt

Explore **F7 — rendered track-changes markdown preview** (baseline-aware, full
mermaid) and write its Solution Design. Anchor Feature #21; deferred intra-diagram
mermaid diffing #22. Builds on F6 baseline (#17/#19). Decisions locked during the
preceding F6-follow-up ideation (session 0019), recorded in #21.

## Outcome

**F7 Solution Design written and graduated.**
`vscode-cowriting-plugin-content/specs/coauthoring-rendered-preview.md` (v0.1.0)
pushed to the content repo (`--status graduated`). Feature **#21** anchors it;
deferred task **#22** (intra-diagram mermaid diffing) captured.

## Plan

Brainstorming → produce the F7 Solution Design from the locked ideation decisions.

## Pre-state

- Main clean, on `origin/main`. F6 shipped (#17 PR #18, #19 PR #20). Epic #1 open.
- This session continues a long conversation: F6 #17 was planned+executed
  (session 0018), the any-file follow-up #19 shipped (session 0019), then the
  operator's manual test of F6 surfaced "the diff view isn't intuitive" → an
  ideation that chose a **rendered track-changes preview** (Option 3) and locked
  its architecture. Issues #21 (F7 feature) + #22 (deferred mermaid) were filed
  during that ideation.

## Turn-by-turn arc

1. **Ideation (pre-session, in conversation).** From the F6 manual-test friction:
   compared single-pane gutter (quick-diff), inline track-changes marks, and a
   rendered preview with change highlights. Operator chose **Option 3** (rendered
   preview). Locked deps strategy (markdown-it + mermaid + diff libs; own the
   integration; no extension-deps, no CDN), the host/webview render split, and
   block-level diff with atomic code/mermaid + whole-diagram mermaid badge.
   Captured #21 (feature, with all decisions in the body) + #22 (deferred
   intra-diagram mermaid diffing).
2. **Claim.** Operator: "kick it off now" → claimed brainstorming session 0020
   (`--type brainstorming`); baseline clean.
3. **Spec.** Wrote `coauthoring-rendered-preview.md` (Solution Design, §1–10):
   custom webview; INV-20..23; reuse F6 baseline + additive `onDidChangeBaseline`;
   command `cowriting.showTrackChangesPreview` (`ctrl+alt+r`, markdown-only);
   4-slice plan; host-E2E tier with the pure render model as the test seam.
   Self-reviewed (no placeholders, consistent names, focused scope).
4. **Review + graduate.** Surfaced the spec + 3 deferred decisions for review.
   Operator thumbs-up → finalize graduated + submitted the spec.

## Cut state

- Spec graduated on the content repo main (`coauthoring-rendered-preview.md`).
- #21 commented (spec graduated); #22 captured (deferred). Epic #1 open.
- Plugin repo `main` clean and synced (no code changed this session).
- No code, tests, or builds this session — it is a brainstorming/spec session.

## Deferred decisions

- **F7 coexists with F6** rather than replacing it — F6's native diff serves any
  file incl. code; F7 is markdown-only. (Operator reviewed; thumbs-up.)
- **`ctrl+alt+r`** as the open keybinding (markdown-only).
- **Webview DOM/mermaid rendering verified by manual smoke**, not automated E2E —
  the sealed webview sandbox can't be DOM-asserted from the host; the automated
  seam is the pure render model (`getLastModel`). All three recorded in spec §9;
  cheap to revisit.

## Next-session prompt

```
/goal Plan and execute Feature #21 (F7 rendered track-changes markdown preview) from the graduated Solution Design at content specs/coauthoring-rendered-preview.md — 4 slices per §7.2, host-E2E tier, no LLM in CI.
```

Read first: `memory/f7-rendered-preview-spec-graduated.md`. The plan starts with
the pure `trackChangesModel` (vscode-free, unit-tested), then the webview asset +
esbuild second entry (bundle mermaid), then the controller/command + F6
`onDidChangeBaseline` event, then host E2E + smoke. Keep mermaid intra-diagram
diffing out (that's #22).