#46 (SLICE-3, accept): Accept all pending proposals in one gesture

Document-edit flow SLICE-3 — completes reach→review→accept
(specs/coauthoring-document-edit-flow.md §7.2, INV-42). A single "Accept all"
gesture applies every pending proposal on the current document through the
existing F4 acceptById seam (block proposals take the INV-40 word-precise path
automatically), in descending anchor order so an earlier accept never invalidates
a later one, skipping (never force-applying) proposals that can't anchor and
reporting applied-vs-skipped. Batched application of the existing accept path — no
new mechanism; the webview posts intent only (INV-35). No confirmation dialog
(undo restores).

- proposalController.ts: acceptAllProposals(document) → {applied, skipped}
  (descending order, orphan-skip); accept/acceptById gain a silent opt so the
  batch suppresses N per-proposal orphan warnings in favour of one report.
- trackChangesPreview.ts: ToolbarMsg += {type:"acceptAll"}; handleWebviewMessage
  routes it to a public acceptAll(document) that batches + reports.
- extension.ts + package.json: cowriting.acceptAllProposals command (active doc,
  markdown-gated palette entry) for the non-webview path.
- media/preview.ts + shellHtml: "✓✓ Accept all" toolbar button, posting the
  intent, shown only with ≥2 pending proposals (authorable, on-state).
- trackChangesModel.ts: diffToBlockHunks now emits one block-aligned hunk per
  CHANGED block even when changed blocks are ADJACENT (treats changed blocks as
  1:1 anchors alongside unchanged ones; gap-spans only cover add/remove runs
  between anchors) — fixes adjacent changed blocks collapsing into one proposal.
- f12Accept host E2E (apply-all reconstructs; orphan skip + report; single
  proposal; command registered/gated); MANUAL-SMOKE-F12 §3.

214 unit + 73/5 host E2E green. Completes the document-edit-flow cluster
(#42 reach + #47 review + #46 accept).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

media/preview.ts

@@ -30,6 +30,7 @@ const legend = document.getElementById("cw-legend")!;
 const annotationsEl = document.getElementById("cw-annotations") as HTMLInputElement | null;
 const pinEl = document.getElementById("cw-pin") as HTMLButtonElement | null;
 const askEl = document.getElementById("cw-ask") as HTMLButtonElement | null;
+const acceptAllEl = document.getElementById("cw-acceptall") as HTMLButtonElement | null;
 
 // F10: the annotations on/off toggle.
 annotationsEl?.addEventListener("change", () => {
@@ -88,6 +89,11 @@ askEl?.addEventListener("click", () => {
   }
 });
 
+// #46 (INV-42): Accept all — batch-accept every pending proposal (intent only).
+acceptAllEl?.addEventListener("click", () => {
+  vscodeApi.postMessage({ type: "acceptAll" });
+});
+
 // F10: delegated ✓/✗ accept/reject of pending proposals (routed back to the F4 seam).
 body.addEventListener("click", (e) => {
   const btn = (e.target as HTMLElement)?.closest<HTMLElement>(".cw-actions button");
@@ -132,6 +138,9 @@ window.addEventListener("message", (event: MessageEvent<RenderMessage>) => {
   if (askEl) askEl.disabled = !authorable;
   const on = msg.mode === "on";
   if (annotationsEl) annotationsEl.checked = on;
+  // #46: Accept all shows only with ≥2 pending proposals, on an authorable doc,
+  // in the annotated (on) state — a single proposal is just a ✓ in place.
+  if (acceptAllEl) acceptAllEl.hidden = !on || !authorable || (msg.summary?.proposals ?? 0) < 2;
   // Off-state is a clean preview: hide the review chrome.
   header.hidden = !on;
   summary.hidden = !on;