diff --git a/knip.json b/knip.json
index 9ce07cf8e..5ac657f65 100644
--- a/knip.json
+++ b/knip.json
@@ -5,6 +5,7 @@
   "vitepress": {
     "entry": ["docs/.vitepress/config.ts"]
   },
+  "ignoreBinaries": ["mkfifo"],
   "ignoreDependencies": ["electron", "esbuild", "webpack"],
   "ignoreExportsUsedInFile": true,
   "rules": {
diff --git a/src/artifacts/AsarArtifactReader.ts b/src/artifacts/AsarArtifactReader.ts
index 674595a04..e231dae96 100644
--- a/src/artifacts/AsarArtifactReader.ts
+++ b/src/artifacts/AsarArtifactReader.ts
@@ -143,14 +143,29 @@ const asarFailure = (
   path: string,
   operation: string,
   cause: unknown,
-): ArtifactReaderFailure =>
-  cause instanceof ArtifactReaderFailure
-    ? cause
-    : new ArtifactReaderFailure(
-        "format",
-        `Malformed or unreadable ASAR during ${operation}: ${path}`,
-        { cause },
-      );
+): ArtifactReaderFailure => {
+  if (cause instanceof ArtifactReaderFailure) return cause;
+  if (isFilesystemFailure(cause))
+    return new ArtifactReaderFailure(
+      "io",
+      `Could not ${operation} ASAR at ${path}: ${cause.message}`,
+      { cause },
+    );
+  return new ArtifactReaderFailure(
+    "format",
+    `Malformed ASAR during ${operation}: ${path}`,
+    { cause },
+  );
+};
+
+const isFilesystemFailure = (
+  cause: unknown,
+): cause is NodeJS.ErrnoException & Error =>
+  cause instanceof Error &&
+  "errno" in cause &&
+  typeof cause.errno === "number" &&
+  "syscall" in cause &&
+  typeof cause.syscall === "string";
 
 const isMissingFile = (cause: unknown): boolean =>
   typeof cause === "object" &&
diff --git a/src/artifacts/DirectoryArtifactReader.ts b/src/artifacts/DirectoryArtifactReader.ts
index db4a37fad..cf4205c9e 100644
--- a/src/artifacts/DirectoryArtifactReader.ts
+++ b/src/artifacts/DirectoryArtifactReader.ts
@@ -85,7 +85,7 @@ export class DirectoryArtifactReader implements ArtifactReader {
       );
     const handle = await open(
       entry.adapterKey,
-      constants.O_RDONLY | constants.O_NOFOLLOW,
+      constants.O_RDONLY | constants.O_NOFOLLOW | constants.O_NONBLOCK,
     );
     try {
       const observed = await handle.stat();
diff --git a/tests/boundary/filesystem/asarInventoryFreshness.test.ts b/tests/boundary/filesystem/asarInventoryFreshness.test.ts
index bd867aa68..4d0932935 100644
--- a/tests/boundary/filesystem/asarInventoryFreshness.test.ts
+++ b/tests/boundary/filesystem/asarInventoryFreshness.test.ts
@@ -110,6 +110,32 @@ describe("ASAR path boundary", () => {
 });
 
 describe("ASAR inventory freshness", () => {
+  it("preserves missing-container I/O as an I/O failure instead of malformed format", async () => {
+    const root = await createTestTempDirectory("rea-asar-missing-");
+    const reader = new AsarArtifactReader(join(root, "missing.asar"));
+
+    await expect(
+      reader.entries()[Symbol.asyncIterator]().next(),
+    ).rejects.toMatchObject({
+      reason: "io",
+      message: expect.stringContaining("ENOENT"),
+    });
+  });
+
+  it("preserves an ASAR path replaced by a directory as a filesystem failure", async () => {
+    const fixture = await archiveFixture();
+    await rm(fixture.archive);
+    await mkdir(fixture.archive);
+    const reader = new AsarArtifactReader(fixture.archive);
+
+    await expect(
+      reader.entries()[Symbol.asyncIterator]().next(),
+    ).rejects.toMatchObject({
+      reason: "io",
+      message: expect.stringContaining("EISDIR"),
+    });
+  });
+
   it.each(["archive", "bundle"] as const)(
     "refreshes a replaced archive when inventorying a %s target",
     async (target) => {
diff --git a/tests/boundary/filesystem/directoryArtifactReaderFifoRace.test.ts b/tests/boundary/filesystem/directoryArtifactReaderFifoRace.test.ts
new file mode 100644
index 000000000..443de83f2
--- /dev/null
+++ b/tests/boundary/filesystem/directoryArtifactReaderFifoRace.test.ts
@@ -0,0 +1,53 @@
+import { writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { randomUUID } from "node:crypto";
+import { fileURLToPath } from "node:url";
+
+import { expect, it } from "vitest";
+
+import {
+  ProviderProcessSupervisor,
+  spawnOwnedProviderProcess,
+} from "../../../src/process/ProviderProcess.js";
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+
+it.skipIf(process.platform === "win32")(
+  "rejects a FIFO replacement without blocking the owner process",
+  async () => {
+    const root = await createTestTempDirectory("rea-directory-fifo-");
+    await writeFile(join(root, "module.js"), "export {}\n");
+    const probe = fileURLToPath(
+      new URL("../../fixtures/directoryReaderFifoProbe.mjs", import.meta.url),
+    );
+    const readerModule = fileURLToPath(
+      new URL(
+        "../../../dist/artifacts/DirectoryArtifactReader.js",
+        import.meta.url,
+      ),
+    );
+    const launch = await spawnOwnedProviderProcess({
+      command: process.execPath,
+      arguments: [probe, readerModule, root],
+      runId: `rea-fifo-probe-${randomUUID()}`,
+      cwd: tmpdir(),
+      hostEnvironment: process.env,
+    });
+    const supervisor = new ProviderProcessSupervisor({
+      ...launch,
+      ownsProcessLifetime: true,
+    });
+
+    try {
+      const closed = await supervisor.waitForOutputClose(2_000);
+      expect(closed).toBe(true);
+      expect(supervisor.snapshot().stdout.text.trim()).toBe("integrity");
+    } finally {
+      const stopped = await supervisor.stop({
+        terminationGraceMs: 100,
+        killGraceMs: 500,
+      });
+      expect(stopped.status).not.toBe("incomplete");
+    }
+  },
+);
diff --git a/tests/fixtures/directoryReaderFifoProbe.mjs b/tests/fixtures/directoryReaderFifoProbe.mjs
new file mode 100644
index 000000000..cbe472c59
--- /dev/null
+++ b/tests/fixtures/directoryReaderFifoProbe.mjs
@@ -0,0 +1,43 @@
+import { execFileSync } from "node:child_process";
+import { open, unlink } from "node:fs/promises";
+import { join } from "node:path";
+import { pathToFileURL } from "node:url";
+
+const [modulePath, root] = process.argv.slice(2);
+if (modulePath === undefined || root === undefined)
+  throw new Error("Directory reader FIFO probe requires module and root paths");
+
+const { DirectoryArtifactReader } = await import(pathToFileURL(modulePath));
+const reader = new DirectoryArtifactReader(root);
+let selected;
+for await (const entry of reader.entries())
+  if (entry.path === "module.js") selected = entry;
+if (selected === undefined)
+  throw new Error("Expected inventoried regular file");
+
+const fifo = join(root, selected.path);
+await unlink(fifo);
+execFileSync("mkfifo", [fifo]);
+
+const opening = reader.open(selected).then(
+  (stream) => {
+    stream.destroy();
+    return "opened";
+  },
+  (cause) =>
+    typeof cause === "object" && cause !== null && "reason" in cause
+      ? String(cause.reason)
+      : "failed",
+);
+const outcome = await Promise.race([
+  opening,
+  new Promise((resolve) => setTimeout(() => resolve("blocked"), 100)),
+]);
+process.stdout.write(`${String(outcome)}\n`);
+
+if (outcome === "blocked") {
+  const writer = await open(fifo, "w");
+  await writer.close();
+  await opening;
+}
+await reader.close();