feat(f9): preview gains authorship mode + attribution dep + setMode wiring

Per-panel mode (default changes); refresh branches to renderAuthorship reading
AttributionController.spansFor; webview setMode message; extension.ts reorders the
F7 controller after attribution. getMode/setMode test seams.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/trackChangesPreview.ts

@@ -11,7 +11,8 @@ import * as path from "node:path";
 import { randomBytes } from "node:crypto";
 import * as vscode from "vscode";
 import type { DiffViewController } from "./diffViewController";
-import { renderTrackChanges, diffBlocks, type BlockOp } from "./trackChangesModel";
+import type { AttributionController } from "./attributionController";
+import { renderTrackChanges, renderAuthorship, diffBlocks, type BlockOp } from "./trackChangesModel";
 
 const VIEW_TYPE = "cowriting.trackChangesPreview";
 const DEBOUNCE_MS = 150;
@@ -21,10 +22,13 @@ export class TrackChangesPreviewController implements vscode.Disposable {
   private readonly panels = new Map<string, vscode.WebviewPanel>();
   private readonly lastModel = new Map<string, BlockOp[]>();
   private readonly debounces = new Map<string, NodeJS.Timeout>();
+  /** F9: per-panel view mode — track-changes (default) or authorship. */
+  private readonly mode = new Map<string, "changes" | "authorship">();
 
   constructor(
     private readonly diffView: DiffViewController,
     private readonly extensionUri: vscode.Uri,
+    private readonly attribution: AttributionController,
   ) {
     this.disposables.push(
       vscode.commands.registerCommand("cowriting.showTrackChangesPreview", () =>
@@ -70,6 +74,18 @@ export class TrackChangesPreviewController implements vscode.Disposable {
       () => {
         this.panels.delete(key);
         this.lastModel.delete(key);
+        this.mode.delete(key);
+      },
+      null,
+      this.disposables,
+    );
+    // F9: the webview's header toggle posts the chosen mode back.
+    panel.webview.onDidReceiveMessage(
+      (m: { type?: string; mode?: "changes" | "authorship" }) => {
+        if (m?.type === "setMode" && (m.mode === "changes" || m.mode === "authorship")) {
+          this.mode.set(key, m.mode);
+          this.refresh(document);
+        }
       },
       null,
       this.disposables,
@@ -97,14 +113,30 @@ export class TrackChangesPreviewController implements vscode.Disposable {
     if (doc) this.refresh(doc);
   }
 
-  /** Recompute the model + post HTML to the panel (no-op if no panel). */
+  /** Recompute the model + post HTML to the panel for its current mode (no-op if no panel). */
   refresh(document: vscode.TextDocument): void {
     const key = document.uri.toString();
     const panel = this.panels.get(key);
     if (!panel) return;
-    const baseline = this.diffView.getBaseline(key);
-    const baselineText = baseline?.text ?? document.getText(); // no baseline → no marks
+    const mode = this.mode.get(key) ?? "changes";
     const current = document.getText();
+    if (mode === "authorship") {
+      // F9: render the current buffer colored by F3 author, baseline-independent.
+      const spans = this.attribution.spansFor(document);
+      this.lastModel.set(key, diffBlocks(this.diffView.getBaseline(key)?.text ?? current, current));
+      void panel.webview.postMessage({
+        type: "render",
+        mode,
+        html: renderAuthorship(current, spans),
+        legend: {
+          claude: spans.some((s) => s.author === "claude"),
+          human: spans.some((s) => s.author === "human"),
+        },
+      });
+      return;
+    }
+    const baseline = this.diffView.getBaseline(key);
+    const baselineText = baseline?.text ?? current; // no baseline → no marks
     const ops = diffBlocks(baselineText, current);
     this.lastModel.set(key, ops);
     const summary = {
@@ -112,11 +144,11 @@ export class TrackChangesPreviewController implements vscode.Disposable {
       removed: ops.filter((o) => o.kind === "removed").length,
       changed: ops.filter((o) => o.kind === "changed").length,
     };
-    const epoch = this.epochLabel(baseline);
     void panel.webview.postMessage({
       type: "render",
+      mode,
       html: renderTrackChanges(baselineText, current),
-      epoch,
+      epoch: this.epochLabel(baseline),
       summary,
     });
   }
@@ -177,6 +209,16 @@ export class TrackChangesPreviewController implements vscode.Disposable {
   getLastModel(uriString: string): BlockOp[] | undefined {
     return this.lastModel.get(uriString);
   }
+  /** F9: current view mode for a panel (default track-changes). */
+  getMode(uriString: string): "changes" | "authorship" {
+    return this.mode.get(uriString) ?? "changes";
+  }
+  /** F9: set the view mode and re-render (the programmatic twin of the header toggle). */
+  setMode(uriString: string, mode: "changes" | "authorship"): void {
+    this.mode.set(uriString, mode);
+    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uriString);
+    if (doc) this.refresh(doc);
+  }
 
   dispose(): void {
     for (const t of this.debounces.values()) clearTimeout(t);