diff --git a/patches/README.md b/patches/README.md
new file mode 100644
index 00000000..b7403138
--- /dev/null
+++ b/patches/README.md
@@ -0,0 +1,101 @@
+# Virtua 0.51.0 macOS WebKit correction boundary
+
+The application imports the React ESM entry (`virtua` → `lib/index.js`) from
+`src/features/messages/ChannelTimeline.tsx`. Only that entry's element scroller is
+patched; CommonJS, window scrolling, and other-framework exports are untouched.
+Keep the dependency pinned to 0.51.0 and review the patch plus version-coupled
+installed-bundle tests before upgrading or adding a different import.
+
+## Failure and chosen boundary
+
+In a system WKWebView, native momentum can overwrite an instant programmatic
+scroll correction. An isolated reproduction adapted from
+[WebKit 262287](https://bugs.webkit.org/show_bug.cgi?id=262287) sustains missing
+pixels even after DOM geometry covers the viewport. The same failure reproduces
+with the production ChannelTimeline and fixed messages when history is prepended.
+This does not attribute every disappearing-content incident to this mechanism.
+
+The previous Mac deferred-store/extent patch is **superseded**. A pause in native
+momentum can outlast Virtua's 150ms inferred-idle timer: the deferred correction
+then runs before native momentum actually ends, and the timeline stays blank.
+One of two paused draft trials failed; this was timing-dependent, not a
+universally failing sequence. Increasing an idle timeout is not the remedy.
+
+Instead, at each **nonzero automatic correction** on Mac WebKit:
+
+1. Temporarily set only the corrected overflow axis to `hidden !important`.
+2. Apply Virtua's original relative correction or absolute edge target.
+3. Restore the prior declaration value and priority in the next task.
+
+This extends the mechanism already used by
+[Virtua's iOS driver](https://github.com/inokawa/virtua/blob/0.51.0/src/core/driver.ts#L203-L248),
+without changing the iOS branch. Overlapping interventions cancel/restore their
+predecessor before capturing the original declaration. Disposal restores
+immediately; an observably changed later declaration is not overwritten.
+
+**Tradeoff:** a correction can stop the remaining trackpad coast. Several size
+corrections can therefore reduce inertial travel more than one prepend. A fresh
+gesture must continue to work; sustained real-history/media acceptance must assess
+whether repeated braking is acceptable. No wheel ownership, permanent scrolling
+CSS, forced layout, alternate store sizing, or new scroll scheduler is introduced.
+
+The platform predicate requires MacIntel and Apple vendor, excluding Virtua's iOS
+detector (including desktop-mode iPad). Chrome/Firefox, non-Mac WebKit and iOS keep
+existing policy. Store/layout/observer timing and imperative smooth/instant
+navigation remain stock. Scheduler-driven reveal/restore/bottom navigation is a
+separate acceptance path, not implicitly repaired by the automatic-correction fix.
+Native reveal controls showed one/two transient blank interior source frames
+before immediate recovery, despite valid sampled DOM coverage. This remaining
+imperative-path flicker is not the sustained automatic-correction failure; the
+patch does not claim to fix it.
+The stale source-map directive is removed because the generated map is unpatched.
+
+## Automated checks
+
+```sh
+bin/pnpm install --frozen-lockfile
+bin/pnpm typecheck
+bin/pnpm exec vitest run src/features/messages/virtua-compensation.test.mjs \
+  src/features/messages/ChannelTimeline.test.tsx
+bin/pnpm test:browser history-loading.spec.mjs image-scroll.spec.mjs initial-position.spec.mjs \
+  --project chromium --project webkit --no-deps --workers=1
+```
+
+The 13 driver/store/observer contracts evaluate the installed React ESM, not a
+copied implementation. They cover active and inferred-idle corrections, zero
+jumps, positive/negative measurements, absolute edges, horizontal RTL, overlapping
+restoration, CSS priority, disposal/remount, later declarations, platform controls,
+and unchanged imperative instant/smooth calls. Copied-bundle mutation controls
+must fail when the production invocation, overlap/dispose restoration, priority,
+or iPad exclusion is removed, or an inferred-scrolling gate is introduced.
+These tests use a fake viewport; they cannot establish native painted pixels.
+
+## Native acceptance and limits
+
+Use an isolated system WKWebView, fixed data, no live identity, and phase-bearing
+native wheel/momentum input confined to that window. Freeze/hash the source,
+installed bundle and runner before each run. Start with a settled production
+ChannelTimeline, prepend during momentum, then repeat with a pause longer than
+150ms before the final momentum event. Compare stock, the superseded draft, and
+the replacement. Capture source video frames separately from DOM/anchor traces.
+
+Require both painted content and the correct identified reading anchor. Repeat
+with a fresh reversed gesture, a second prepend at the bottom, a fresh upward
+gesture, positive/negative row measurement changes, and explicitly gated local
+images. Check restoration and continued movement, not just final scrollTop.
+Exercise imperative reveal/restore/bottom controls separately. A pending image
+placeholder and bottom rubberband/fractional edge gaps are not missing tiles.
+
+Observed on macOS 26.6.2: stock and a paused old-draft trial sustain blank message
+pixels; the replacement preserves content and correction anchors in the matched
+native trials. Repeated native gestures and local images continue to paint, with
+the braking tradeoff above. Ordinary Chromium/WebKit browser history, image and
+initial-position journeys provide additional behavioral coverage, **not equivalent
+native momentum/compositor evidence**.
+
+The fixed-data native fixture does not fetch real older history. Three-second
+movies are not four seconds of pixel evidence just because DOM traces run longer;
+movie and JavaScript clocks are not synchronized. These bounded results are not
+signed-package/cross-platform acceptance or verification of the original user's
+sustained real-message incident. Keep the change draft until that acceptance is
+completed; do not restart a running app without coordination.
diff --git a/patches/virtua@0.51.0.patch b/patches/virtua@0.51.0.patch
new file mode 100644
index 00000000..a1d36783
--- /dev/null
+++ b/patches/virtua@0.51.0.patch
@@ -0,0 +1,55 @@
+diff --git a/lib/index.js b/lib/index.js
+--- a/lib/index.js
++++ b/lib/index.js
+@@ -7,1 +7,5 @@
+ import { flushSync as f } from "react-dom";
++
++// WebKit can restore a stale native scroll offset after an instant correction.
++// Interrupt only the corrected axis; observer-inferred idle is not native idle.
++const isMacWebKit = () => typeof navigator !== "undefined" && !b() && navigator.platform === "MacIntel" && navigator.vendor === "Apple Computer, Inc.";
+@@ -249,7 +253,22 @@
+         o && o();
+     } ];
+ }, E = (e, t) => {
+-    let n, o, r = $(), i = !1;
++    let n, o, r = $(), i = !1, restoreOverflow;
++    const interruptMomentum = () => {
++        // Repeated corrections in one task share the original declaration.
++        restoreOverflow && restoreOverflow();
++        const style = n.style, property = t ? "overflow-x" : "overflow-y";
++        const value = style.getPropertyValue(property), priority = style.getPropertyPriority(property);
++        style.setProperty(property, "hidden", "important");
++        const restore = () => {
++            S(timer);
++            if (style.getPropertyValue(property) === "hidden" && style.getPropertyPriority(property) === "important") {
++                value ? style.setProperty(property, value, priority) : style.removeProperty(property);
++            }
++            restoreOverflow = void 0;
++        }, timer = p(restore);
++        restoreOverflow = restore;
++    };
+     const s = t ? "scrollLeft" : "scrollTop", l = t ? "left" : "top", c = t ? "overflowX" : "overflowY", [f, a] = O(e, () => r[0], (e, t) => {
+         n.scrollTo({
+             [l]: T(e, i),
+@@ -266,7 +285,8 @@
+     return {
+         D(f, u = f.parentElement) {
+             h.A(n = u), t && (i = "rtl" === getComputedStyle(u).direction), o = M(e, u, t, () => T(u[s], i), (t, n, o) => {
+-                if (o) {
++                if (isMacWebKit()) interruptMomentum();
++                else if (o) {
+                     const e = u.style, t = e[c];
+                     e[c] = "hidden", p(() => {
+                         e[c] = t;
+@@ -283,7 +303,7 @@
+             }), r[1](!0);
+         },
+         _() {
+-            h.X(), o && o.X(), r[1](!1), r = $();
++            restoreOverflow && restoreOverflow(), h.X(), o && o.X(), r[1](!1), r = $();
+         },
+         P: (e, t) => (d.set(e, t), h.A(e), () => {
+             d.delete(e), h.B(e);
+@@ -799,2 +819,1 @@
+ export { G as VList, j as Virtualizer, U as WindowVirtualizer, N as experimental_VGrid };
+-//# sourceMappingURL=index.js.map
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 55a44e61..855889e9 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4,6 +4,9 @@ settings:
   autoInstallPeers: true
   excludeLinksFromLockfile: false
 
+patchedDependencies:
+  virtua@0.51.0: 14ff685d9bc68b34d1a7c6b0042d6000e4b07a9746088fc3842c89c4a995ca9d
+
 importers:
 
   .:
@@ -76,7 +79,7 @@ importers:
         version: 4.0.1
       virtua:
         specifier: 0.51.0
-        version: 0.51.0(react-dom@19.2.8(react@19.2.8))(react@19.2.8)
+        version: 0.51.0(patch_hash=14ff685d9bc68b34d1a7c6b0042d6000e4b07a9746088fc3842c89c4a995ca9d)(react-dom@19.2.8(react@19.2.8))(react@19.2.8)
     devDependencies:
       '@biomejs/biome':
         specifier: 2.5.12
@@ -2955,7 +2958,7 @@ snapshots:
       '@types/unist': 3.0.3
       vfile-message: 4.0.3
 
-  virtua@0.51.0(react-dom@19.2.8(react@19.2.8))(react@19.2.8):
+  virtua@0.51.0(patch_hash=14ff685d9bc68b34d1a7c6b0042d6000e4b07a9746088fc3842c89c4a995ca9d)(react-dom@19.2.8(react@19.2.8))(react@19.2.8):
     optionalDependencies:
       react: 19.2.8
       react-dom: 19.2.8(react@19.2.8)
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
new file mode 100644
index 00000000..6bab0058
--- /dev/null
+++ b/pnpm-workspace.yaml
@@ -0,0 +1,2 @@
+patchedDependencies:
+  virtua@0.51.0: patches/virtua@0.51.0.patch
diff --git a/src/features/messages/virtua-compensation.test.mjs b/src/features/messages/virtua-compensation.test.mjs
new file mode 100644
index 00000000..696f24e5
--- /dev/null
+++ b/src/features/messages/virtua-compensation.test.mjs
@@ -0,0 +1,251 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { afterEach, beforeEach, expect, it, vi } from "vitest";
+
+// Exercise the installed React ESM's actual store, observer and element driver.
+// Names are deliberately version-coupled: review this extraction on upgrade.
+const source = readFileSync(
+  fileURLToPath(import.meta.resolve("virtua")),
+  "utf8",
+);
+const start = source.indexOf("var {min:");
+const end = source.indexOf("}, W = (e, t) => {");
+if (start < 0 || end < 0)
+  throw new Error("Review Virtua driver extraction after version change");
+const helperStart = source.indexOf("const isMacWebKit =");
+const helper = helperStart >= 0 ? source.slice(helperStart, start) : "";
+const core = source.slice(start, end + 1);
+
+beforeEach(() => vi.useFakeTimers());
+afterEach(() => vi.useRealTimers());
+
+function setup({
+  platform = "MacIntel",
+  vendor = "Apple Computer, Inc.",
+  touch = 0,
+  agent = "Macintosh",
+  horizontal = false,
+  direction = "ltr",
+  offset = 1300,
+} = {}) {
+  const {
+    store: createStore,
+    layout,
+    driver: createDriver,
+  } = new Function(
+    "navigator",
+    "getComputedStyle",
+    `${helper}${core};return {store:y,layout:R,driver:E};`,
+  )({ platform, vendor, maxTouchPoints: touch, userAgent: agent }, () => ({
+    direction,
+  }));
+  const store = createStore(layout(20, 100));
+  const declarations = new Map();
+  const style = {
+    getPropertyValue: (name) => declarations.get(name)?.[0] ?? "",
+    getPropertyPriority: (name) => declarations.get(name)?.[1] ?? "",
+    setProperty: (name, value, priority = "") =>
+      declarations.set(name, [value, priority]),
+    removeProperty: (name) => declarations.delete(name),
+  };
+  const viewport = new EventTarget();
+  const calls = [];
+  const axis = horizontal ? "overflow-x" : "overflow-y";
+  const key = horizontal ? "scrollLeft" : "scrollTop";
+  const option = horizontal ? "left" : "top";
+  Object.assign(viewport, {
+    style,
+    offsetParent: {},
+    scrollTop: 0,
+    scrollLeft: 0,
+    ownerDocument: {
+      defaultView: {
+        ResizeObserver: class {
+          observe() {}
+          unobserve() {}
+          disconnect() {}
+        },
+      },
+    },
+  });
+  viewport[key] = direction === "rtl" ? -offset : offset;
+  for (const method of ["scrollTo", "scrollBy"])
+    viewport[method] = (options) => {
+      calls.push({
+        method,
+        options,
+        overflow: style.getPropertyValue(axis),
+        priority: style.getPropertyPriority(axis),
+      });
+      viewport[key] =
+        (method === "scrollBy" ? viewport[key] : 0) + options[option];
+    };
+  store.W(4, 500); // measured viewport
+  store.W(1, offset); // observed native scrolling
+  const driver = createDriver(store, horizontal);
+  driver.D({}, viewport);
+  return {
+    store,
+    driver,
+    viewport,
+    style,
+    axis,
+    calls,
+    prepend(length = 40) {
+      store.W(5, [length, true]);
+      driver.J();
+    },
+  };
+}
+
+it("interrupts the actual correction before its relative DOM write, even after inferred idle", () => {
+  const c = setup();
+  c.store.W(2); // observer idle is NOT native momentum completion
+  c.prepend();
+  expect(c.calls).toEqual([
+    {
+      method: "scrollBy",
+      options: { top: 2000, behavior: "instant" },
+      overflow: "hidden",
+      priority: "important",
+    },
+  ]);
+  expect(c.viewport.scrollTop).toBe(3300);
+  expect(c.store.t()).toBe(4000); // no deferred extent/store policy
+  expect(c.store.u(39)).toBe(3900);
+  c.driver.J();
+  expect(c.calls).toHaveLength(1);
+  vi.runAllTimers();
+  expect(c.style.getPropertyValue(c.axis)).toBe("");
+  expect(vi.getTimerCount()).toBe(0);
+});
+
+it("does not defer while scrolling or interrupt without a correction", () => {
+  const c = setup();
+  c.driver.J();
+  expect(c.calls).toHaveLength(0);
+  expect(vi.getTimerCount()).toBe(0);
+  c.prepend();
+  expect(c.calls).toHaveLength(1);
+  expect(c.store.t()).toBe(4000);
+  expect(c.store.L()[0]).toBe(0);
+});
+
+it("preserves absolute edge correction and RTL axis normalization", () => {
+  for (const config of [
+    { offset: 1500 },
+    { horizontal: true, direction: "rtl", offset: 1500 },
+  ]) {
+    const c = setup(config);
+    c.prepend();
+    expect(c.calls).toEqual([
+      {
+        method: "scrollTo",
+        options: {
+          [config.horizontal ? "left" : "top"]: config.horizontal
+            ? -3500
+            : 3500,
+          behavior: "instant",
+        },
+        overflow: "hidden",
+        priority: "important",
+      },
+    ]);
+    c.driver._();
+  }
+});
+
+it("restores exact value and priority after overlapping corrections without touching the other axis", () => {
+  const c = setup();
+  c.style.setProperty("overflow-y", "scroll", "important");
+  c.style.setProperty("overflow-x", "clip", "");
+  c.prepend();
+  c.prepend(60);
+  expect(c.calls.map((call) => call.overflow)).toEqual(["hidden", "hidden"]);
+  expect(vi.getTimerCount()).toBe(1);
+  expect(c.style.getPropertyValue("overflow-x")).toBe("clip");
+  vi.runAllTimers();
+  expect(c.style.getPropertyValue("overflow-y")).toBe("scroll");
+  expect(c.style.getPropertyPriority("overflow-y")).toBe("important");
+});
+
+it("restores immediately on dispose and permits a fresh lifecycle", () => {
+  const c = setup();
+  c.style.setProperty(c.axis, "auto");
+  c.prepend();
+  c.driver._();
+  expect(c.style.getPropertyValue(c.axis)).toBe("auto");
+  expect(c.style.getPropertyPriority(c.axis)).toBe("");
+  expect(vi.getTimerCount()).toBe(0);
+  c.driver.D({}, c.viewport);
+  c.prepend(60);
+  expect(c.calls.at(-1).overflow).toBe("hidden");
+  c.driver._();
+  expect(c.style.getPropertyValue(c.axis)).toBe("auto");
+});
+
+it("does not overwrite a later style owner", () => {
+  const c = setup();
+  c.prepend();
+  c.style.setProperty(c.axis, "clip", "important");
+  vi.runAllTimers();
+  expect(c.style.getPropertyValue(c.axis)).toBe("clip");
+  expect(c.style.getPropertyPriority(c.axis)).toBe("important");
+});
+
+it("interrupts positive and negative resize compensation at the same production driver", () => {
+  for (const size of [50, 150]) {
+    const c = setup();
+    c.store.W(3, [[0, size]]);
+    c.driver.J();
+    expect(c.calls).toEqual([
+      {
+        method: "scrollBy",
+        options: { top: size - 100, behavior: "instant" },
+        overflow: "hidden",
+        priority: "important",
+      },
+    ]);
+    c.driver._();
+  }
+});
+
+it("does not change the imperative scheduler's smooth or instant scrolling policy", async () => {
+  for (const smooth of [false, true]) {
+    const c = setup();
+    c.store.W(
+      3,
+      Array.from({ length: 20 }, (_, index) => [index, 100]),
+    );
+    await c.driver.V(() => 900, smooth);
+    await vi.advanceTimersByTimeAsync(0);
+    expect(c.calls.at(-1).overflow).toBe("");
+    expect(c.calls.at(-1).options).toEqual({
+      top: 900,
+      behavior: smooth ? "smooth" : "instant",
+    });
+    c.driver._();
+    vi.clearAllTimers();
+  }
+});
+
+for (const [name, config, deferred] of [
+  ["macOS Chrome", { vendor: "Google Inc." }, false],
+  ["macOS Firefox", { vendor: "" }, false],
+  ["Linux WebKit", { platform: "Linux x86_64" }, false],
+  ["desktop-mode iPad", { touch: 5 }, true],
+  ["iPhone", { platform: "iPhone", agent: "iPhone", touch: 5 }, true],
+]) {
+  it(`preserves existing ${name} policy`, () => {
+    const c = setup(config);
+    c.prepend();
+    expect(c.calls).toHaveLength(deferred ? 0 : 1);
+    if (deferred) {
+      c.store.W(2);
+      c.driver.J();
+    }
+    expect(c.calls.at(-1).overflow).toBe("");
+    expect(c.store.t()).toBe(4000);
+    c.driver._();
+  });
+}
diff --git a/tests/browser/emoji.spec.mjs b/tests/browser/emoji.spec.mjs
index 827b6c8d..c7809b0a 100644
--- a/tests/browser/emoji.spec.mjs
+++ b/tests/browser/emoji.spec.mjs
@@ -677,10 +677,32 @@ test("community picker uses keyboard, proxy thumbnails, event-local history and
     await expect(region.getByRole("alert")).toContainText(
       "Fixture catalog offline",
     );
-    await page.evaluate(() => window.emojiFixture.fail(false));
-    await page
-      .getByRole("button", { name: "Retry emoji", exact: true })
-      .click();
+    await page.evaluate(() => {
+      window.emojiFixture.fail(false);
+      window.emojiFixture.holdCatalog();
+    });
+    try {
+      await page
+        .getByRole("button", { name: "Retry emoji", exact: true })
+        .click();
+      await expect
+        .poll(() => page.evaluate(() => window.emojiFixture.status("a")))
+        .toBe("loading");
+      // A usable Unicode-only picker during loading is not the recovered mount.
+      await expect(search).toHaveAttribute("data-buzz-search-ready", "true");
+      await expect(
+        page.locator('em-emoji-picker [data-id="buzz-custom"]'),
+      ).toHaveCount(0);
+    } finally {
+      await page.evaluate(() => window.emojiFixture.releaseCatalog());
+    }
+    await expect
+      .poll(() => page.evaluate(() => window.emojiFixture.status("a")))
+      .toBe("ready");
+    await expect(
+      page.locator('em-emoji-picker [data-id="buzz-custom"]'),
+    ).toHaveCount(1);
+    await expect(search).toHaveAttribute("data-buzz-search-ready", "true");
     await search.fill("party");
     await expect(insert).toBeVisible();
     await draft().fill(":broken: readable");
diff --git a/tests/browser/layout.spec.mjs b/tests/browser/layout.spec.mjs
index 9ddd1ecb..a10d1dec 100644
--- a/tests/browser/layout.spec.mjs
+++ b/tests/browser/layout.spec.mjs
@@ -48,7 +48,16 @@ async function link(page, app, target) {
     }),
   );
   app.append("primary", "alpha", `Please review ${target}`);
-  await page.getByRole("link", { name: target, exact: true }).click();
+  const trigger = page.getByRole("link", { name: target, exact: true });
+  await expect(trigger).toBeVisible();
+  await trigger.scrollIntoViewIfNeeded();
+  // Appending and bringing an offscreen link into view can both scroll Virtua.
+  // These are panel-layout checks, not clicks during an in-flight correction.
+  await settle(page);
+  await expect(
+    page.getByRole("region", { name: "Channel message history" }).locator("ol"),
+  ).toHaveCSS("pointer-events", "auto");
+  await trigger.click();
   await expect(
     panel(page).getByRole("heading", { name: "A useful change" }),
   ).toBeVisible();
diff --git a/tests/fixtures/emoji.tsx b/tests/fixtures/emoji.tsx
index e4feef05..c7b92f11 100644
--- a/tests/fixtures/emoji.tsx
+++ b/tests/fixtures/emoji.tsx
@@ -39,6 +39,8 @@ const sessions = ["a", "b"].map((community) => {
   let time = 1,
     fail = false;
   let live!: LiveCallbacks;
+  let catalogRead: Promise<void> | undefined;
+  let releaseCatalogRead: (() => void) | undefined;
   const makeSet = (empty = false) =>
     signed(member, {
       kind: 30030,
@@ -90,7 +92,7 @@ const sessions = ["a", "b"].map((community) => {
       async query(filters) {
         if (filters[0]?.kinds?.includes(30030)) {
           report.reads.push(community);
-          await new Promise((resolve) => setTimeout(resolve, 80));
+          await catalogRead;
           if (fail) throw new Error("Fixture catalog offline");
           return [catalog];
         }
@@ -152,6 +154,17 @@ const sessions = ["a", "b"].map((community) => {
     fail(value: boolean) {
       fail = value;
     },
+    holdCatalog() {
+      if (catalogRead) throw new Error("Catalog read already held");
+      catalogRead = new Promise<void>((resolve) => {
+        releaseCatalogRead = resolve;
+      });
+    },
+    releaseCatalog() {
+      releaseCatalogRead?.();
+      catalogRead = undefined;
+      releaseCatalogRead = undefined;
+    },
   };
 });
 Object.assign(window, {
@@ -161,6 +174,8 @@ Object.assign(window, {
     remove: () => sessions[0]?.replace(true),
     fail: (value: boolean) => sessions[0]?.fail(value),
     refresh: () => sessions[0]?.session.emoji.refresh(),
+    holdCatalog: () => sessions[0]?.holdCatalog(),
+    releaseCatalog: () => sessions[0]?.releaseCatalog(),
     status: (community: string) =>
       sessions
         .find((item) => item.community === community)
diff --git a/tests/integration/hooks.test.mjs b/tests/integration/hooks.test.mjs
index c1ad9893..ce70a866 100644
--- a/tests/integration/hooks.test.mjs
+++ b/tests/integration/hooks.test.mjs
@@ -18,6 +18,9 @@ const root = fileURLToPath(new URL("../../", import.meta.url));
 const env = Object.fromEntries(
   Object.entries(process.env).filter(([key]) => !key.startsWith("GIT_")),
 );
+// Borrow the installed tools without letting pnpm repair the shared symlink target.
+// This fixture intentionally has no workspace/patch config of its own.
+env.pnpm_config_verify_deps_before_run = "false";
 // These commits are disposable probe fixtures, never commits in the source checkout.
 env.GIT_CONFIG_NOSYSTEM = "1";
 env.GIT_CONFIG_GLOBAL = "/dev/null";
@@ -76,7 +79,12 @@ function fixture(t) {
   return { dir, sibling, run, git, write, read, install, commit };
 }
 
-test("installed hook formats and safely fixes staged files without including other work", (t) => {
+test("installed hook formats without rewriting borrowed dependencies or other work", (t) => {
+  const dependencies = () =>
+    [".modules.yaml", "virtua/lib/index.js"].map((file) =>
+      readFileSync(path.join(root, "node_modules", file), "utf8"),
+    );
+  const installed = dependencies();
   const f = fixture(t);
   f.write("nested/space name.ts", "export const answer={value:42}\n");
   f.write("safe.ts", "export function count(){let value=1; return value;}\n");
@@ -85,6 +93,7 @@ test("installed hook formats and safely fixes staged files without including oth
   f.write("untracked.ts", "export const doNotAdd={value:1}\n");
   const result = f.commit();
   assert.equal(result.status, 0, result.stdout + result.stderr);
+  assert.deepEqual(dependencies(), installed, "borrowed dependencies changed");
   assert.equal(
     f.git("show", "HEAD:nested/space name.ts"),
     "export const answer = { value: 42 };\n",