feat(documents): multi-select bulk actions on the vault timeline

Selection grows file-manager gestures — shift-click ranges (additive,
anchored on the last plain toggle) and press-and-hold on touch — and a
floating toolbar appears with the selected count and the bulk verbs:
change type, link condition, delete, clear. All verbs drive the bulk
endpoint in <=100-id chunks with merged per-id results; partial failures
surface as one counted toast, and a bulk delete gets one aggregate undo
that bulk-restores the succeeded rows (both sides no-op-safe by
contract). Escape clears the selection unless a dialog owns the key.

Refs: document-vault plan W3-T2

src/components/documents/__tests__/document-bulk-bar.test.tsx

@@ -0,0 +1,46 @@
+import { describe, expect, it } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+/**
+ * The floating bulk bar, pinned via single-pass static renders: a labelled
+ * toolbar carrying the selected count and the four bulk verbs. The
+ * link-condition menu only renders when the account actually has episodes
+ * to link — no dead affordance on an episode-free account.
+ */
+import { I18nProvider } from "@/lib/i18n/context";
+import { DocumentBulkBar } from "../document-bulk-bar";
+
+function render(episodes: { id: string; label: string }[]) {
+  return renderToStaticMarkup(
+    <I18nProvider initialLocale="en">
+      <DocumentBulkBar
+        selectedCount={3}
+        episodes={episodes}
+        busy={false}
+        onSetKind={() => {}}
+        onLinkEpisode={() => {}}
+        onDelete={() => {}}
+        onClear={() => {}}
+      />
+    </I18nProvider>,
+  );
+}
+
+describe("<DocumentBulkBar>", () => {
+  it("renders a labelled toolbar with count and the bulk verbs", () => {
+    const html = render([{ id: "ep1", label: "Knee" }]);
+    expect(html).toContain('data-slot="document-bulk-bar"');
+    expect(html).toContain('role="toolbar"');
+    expect(html).toContain("3 selected");
+    expect(html).toContain("Change type");
+    expect(html).toContain("Link condition");
+    expect(html).toContain("Delete");
+    expect(html).toContain("Clear selection");
+  });
+
+  it("omits the link-condition verb when the account has no episodes", () => {
+    const html = render([]);
+    expect(html).not.toContain("Link condition");
+    expect(html).toContain("Change type");
+  });
+});

src/components/documents/__tests__/vault-utils.test.ts

@@ -7,6 +7,7 @@ import {
   classifyUploadFailure,
   countActiveFilters,
   documentDateKey,
+  expandRangeSelection,
   formatBytes,
   formatMonthLabel,
   parseUploadResponse,
@@ -252,3 +253,31 @@ describe("upload response contract (§3.2)", () => {
     expect(parseUploadResponse(500, "")).toMatchObject({ reason: "generic" });
   });
 });
+
+describe("shift-click range selection", () => {
+  const order = ["a", "b", "c", "d", "e"];
+
+  it("selects the inclusive range between anchor and target, both ways", () => {
+    expect(
+      [...expandRangeSelection(order, new Set(["b"]), "b", "d")].sort(),
+    ).toEqual(["b", "c", "d"]);
+    expect(
+      [...expandRangeSelection(order, new Set(["d"]), "d", "b")].sort(),
+    ).toEqual(["b", "c", "d"]);
+  });
+
+  it("is additive — a range gesture never deselects", () => {
+    const next = expandRangeSelection(order, new Set(["a", "c"]), "c", "e");
+    expect([...next].sort()).toEqual(["a", "c", "d", "e"]);
+  });
+
+  it("falls back to a plain toggle without a live anchor", () => {
+    expect([...expandRangeSelection(order, new Set(), null, "c")]).toEqual([
+      "c",
+    ]);
+    // Anchor filtered out of the current order → plain toggle (deselect).
+    expect([
+      ...expandRangeSelection(order, new Set(["c"]), "gone", "c"),
+    ]).toEqual([]);
+  });
+});