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+# 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).
diff --git a/sessions/0020/SESSION-0020.0-TRANSCRIPT-2026-06-11T08-19--INPROGRESS.md b/sessions/0020/SESSION-0020.0-TRANSCRIPT-2026-06-11T08-19--INPROGRESS.md
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-# Session 0020.0 — Transcript
-
-> App: vscode-cowriting-plugin
-> Start: 2026-06-11T08-19 (PST)
-> Type: brainstorming
-> Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
->
-> This file reserves session ID 0020 for vscode-cowriting-plugin. The driver replaces this
-> body with the full transcript and renames the file to its final
-> SESSION-0020.0-TRANSCRIPT-2026-06-11T08-19--<end>.md form at session end.
-
-## Launch prompt
-
-```
-Brainstorming: explore F7 (rendered track-changes markdown preview, baseline-aware, full mermaid) and write its Solution Design. Anchor Feature #21; deferred mermaid intra-diagram diffing #22. Builds on F6 baseline (#17/#19). Locked: custom webview; markdown-it + mermaid + jsdiff deps; block-level diff + atomic mermaid whole-diagram changed badge.
-
-```
-
-## Deferred decisions
-
-_Autonomous-mode low-confidence calls the driver made and would have
-liked operator input on. Appended as the session runs; surfaced at
-finalize. Empty if none._