diff --git a/README.md b/README.md
index 403b223..4b6c82b 100644
--- a/README.md
+++ b/README.md
@@ -196,6 +196,20 @@ the manual smoke, not the sealed-sandbox E2E.
 Design: `vscode-cowriting-plugin-content/specs/coauthoring-rendered-preview.md`.
 Live smoke: [`docs/MANUAL-SMOKE-F7.md`](docs/MANUAL-SMOKE-F7.md).
 
+## F9 — Authorship view in the preview (Feature ~#27)
+
+The rendered preview (F7) gains a second mode, switched by a `[ Track changes |
+Authorship ]` toggle in its header. **Authorship** mode re-renders the current
+document with each span colored by its F3 author — Claude (blue) vs you (green),
+inline and char-precise — with a legend. Unlike track-changes (which diffs against
+the F6 baseline, and so hides Claude's text once the baseline advances past a
+landing), authorship reads F3 attribution directly, so Claude's contributions stay
+visible. Code/mermaid fences carry a block-level author badge (atomic). Read-only,
+sealed webview, no new persistence (INV-26..28).
+
+Design: `docs/superpowers/specs/2026-06-11-authorship-preview-design.md`.
+Live smoke: [`docs/MANUAL-SMOKE-F9.md`](docs/MANUAL-SMOKE-F9.md).
+
 ## F8 — Out-of-workspace authoring (Feature #25)
 
 "Ask Claude to Edit Selection" (and F2 threads / F3 attribution / F4
diff --git a/docs/MANUAL-SMOKE-F9.md b/docs/MANUAL-SMOKE-F9.md
new file mode 100644
index 0000000..3d2e5d0
--- /dev/null
+++ b/docs/MANUAL-SMOKE-F9.md
@@ -0,0 +1,21 @@
+# Manual smoke — F9 authorship view in the preview
+
+Confirms the rendered preview's Authorship mode colors Claude's vs your text. One
+live turn hits the SDK.
+
+## Prereqs
+- `npm run build`; launch the Extension Development Host (F5) with `sandbox/` open.
+
+## Steps
+1. Open a markdown file. Open **Cowriting: Open Track-Changes Preview** (`Ctrl+Alt+R`).
+2. The header shows a `[ Track changes | Authorship ]` toggle. It opens in **Track
+   changes** (unchanged behavior).
+3. Select a sentence → **Ask Claude to Edit Selection** → instruct → accept.
+4. Click **Authorship**. Expect: Claude's accepted text is tinted (blue) and your
+   own typing is tinted (green); the header shows a legend (Claude / You). Text you
+   never touched (original content) is plain.
+5. Type a few words yourself, mixing into a Claude sentence. Expect: the colors
+   split mid-paragraph at the exact boundaries.
+6. If the doc has a mermaid or code fence Claude authored, expect the whole fence
+   to carry a small author badge (not per-character).
+7. Flip back to **Track changes**. Expect: the diff view is exactly as before.