diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 97025afe7..6d03dc87e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -415,6 +415,7 @@ jobs:
           tests/boundary/filesystem/binaryTarget.test.ts
           tests/boundary/filesystem/safeOutputTree.test.ts
           tests/boundary/providers/native/artifactProvider.archiveSafety.test.ts
+          tests/boundary/providers/native/artifactProvider.extractionCompleteness.test.ts
           tests/boundary/filesystem/setupUnavailableProvider.test.ts
           tests/boundary/filesystem/windowsNpxRegistration.test.ts
           tests/boundary/filesystem/webScriptManifestPaths.test.ts
diff --git a/tests/boundary/providers/native/artifactProvider.extractionCompleteness.test.ts b/tests/boundary/providers/native/artifactProvider.extractionCompleteness.test.ts
index e5994c79a..778a80f33 100644
--- a/tests/boundary/providers/native/artifactProvider.extractionCompleteness.test.ts
+++ b/tests/boundary/providers/native/artifactProvider.extractionCompleteness.test.ts
@@ -1,11 +1,12 @@
+import { createHash } from "node:crypto";
+import { watch } from "node:fs";
 import { access, mkdir, readFile, rm, writeFile } from "node:fs/promises";
-import { join } from "node:path";
+import { basename, dirname, join } from "node:path";
 
 import { createPackage, createPackageWithOptions } from "@electron/asar";
-import { expect, it, onTestFinished, vi } from "vitest";
+import { expect, it, onTestFinished } from "vitest";
 
 import { ArtifactProvider } from "../../../../src/artifacts/ArtifactProvider.js";
-import { SafeOutputTree } from "../../../../src/artifacts/SafeOutputTree.js";
 import { artifactExtractionResultSchema } from "../../../../src/domain/artifactGraph.js";
 import { projectAnalysisError } from "../../../../src/domain/analysisErrorProjection.js";
 import { createTestTempDirectory } from "../../../fixtures/temporaryDirectory.js";
@@ -17,10 +18,11 @@ it.each(["file", "directory"] as const)(
     const source = join(root, "source");
     await mkdir(join(source, "z"), { recursive: true });
     // Equal bytes share an artifact node, but both occurrences must be copied.
-    await writeFile(join(source, "a.txt"), "same bytes\n");
-    await writeFile(join(source, "z", "missing.txt"), "same bytes\n");
+    const bytes = Buffer.alloc(8 * 1024 * 1024, "same bytes\n");
+    await writeFile(join(source, "a.txt"), bytes);
+    await writeFile(join(source, "z", "missing.txt"), bytes);
     const output = join(root, "output");
-    afterInventory(async () => {
+    const changed = afterInventory(output, async () => {
       await rm(
         removedKind === "file"
           ? join(source, "z", "missing.txt")
@@ -30,18 +32,36 @@ it.each(["file", "directory"] as const)(
     });
 
     const result = await extract(source, output);
+    await changed();
     if (result.ok) throw new Error("Incomplete extraction must fail");
-    expect(projectAnalysisError(result.error)).toMatchObject({
+    const projected = projectAnalysisError(result.error);
+    expect(projected).toMatchObject({
       code: "artifact_operation_failed",
       details: {
         operation: "extract_artifact",
+      },
+    });
+    // A directory already returned by readdir can disappear before its stat.
+    // That earlier reader failure retains ENOENT instead of reaching the final
+    // completeness check. Both paths must reject publication and roll back.
+    if (removedKind === "directory" && projected.details?.reason === "io") {
+      expect(projected.details).toMatchObject({
+        reason: "io",
+        detail: `Could not inspect entry at ${join(source, "z")} (ENOENT)`,
+      });
+    } else {
+      expect(projected.details).toMatchObject({
         reason: "integrity",
         detail:
           "Inventoried regular artifact entries were not materialized: z/missing.txt",
-      },
-    });
+      });
+    }
     await expect(access(output)).rejects.toThrow();
-    expect(await readFile(join(source, "a.txt"), "utf8")).toBe("same bytes\n");
+    expect(
+      createHash("sha256")
+        .update(await readFile(join(source, "a.txt")))
+        .digest("hex"),
+    ).toBe(createHash("sha256").update(bytes).digest("hex"));
   },
 );
 
@@ -49,12 +69,16 @@ it("still refuses a regular file added after inventory and rolls back", async ()
   const root = await createTestTempDirectory("rea-extract-added-");
   const source = join(root, "source");
   await mkdir(source);
-  await writeFile(join(source, "a.txt"), "original\n");
+  await writeFile(
+    join(source, "a.txt"),
+    Buffer.alloc(8 * 1024 * 1024, "original\n"),
+  );
   const output = join(root, "output");
-  afterInventory(async () => {
+  const changed = afterInventory(output, async () => {
     await writeFile(join(source, "z.txt"), "new\n");
   });
   const result = await extract(source, output);
+  await changed();
   if (result.ok) throw new Error("Changed inventory must fail");
   expect(projectAnalysisError(result.error)).toMatchObject({
     details: {
@@ -136,18 +160,27 @@ it("ignores unavailable members of a nested ASAR but refuses them as active entr
   await expect(access(activeOutput)).rejects.toThrow();
 });
 
-// Synchronize a real filesystem change after the actual inventory scan. The
-// production reader, writes, failure translation and rollback all remain real.
-const afterInventory = (change: () => Promise<void>): void => {
-  const create = SafeOutputTree.create;
-  const hook = vi
-    .spyOn(SafeOutputTree, "create")
-    .mockImplementationOnce(async (...args) => {
-      const output = await create(...args);
-      await change();
-      return output;
-    });
-  onTestFinished(() => hook.mockRestore());
+// The real destination is created only after inventory. A streamed first file
+// leaves time to mutate a later entry without replacing any production method.
+const afterInventory = (output: string, change: () => Promise<void>) => {
+  let mutation:
+    | Promise<{ ok: true } | { ok: false; cause: unknown }>
+    | undefined;
+  const watcher = watch(dirname(output), (_event, filename) => {
+    if (filename !== basename(output) || mutation !== undefined) return;
+    watcher.close();
+    mutation = change().then(
+      () => ({ ok: true as const }),
+      (cause: unknown) => ({ ok: false as const, cause }),
+    );
+  });
+  onTestFinished(() => watcher.close());
+  return async () => {
+    if (mutation === undefined)
+      throw new Error("Extraction destination was not observed");
+    const result = await mutation;
+    if (!result.ok) throw result.cause;
+  };
 };
 
 const extract = (source: string, output: string) =>