diff --git a/src/process/ProviderDeadline.test.ts b/src/process/ProviderDeadline.test.ts
index 2ecd6402c..ca83d98ab 100644
--- a/src/process/ProviderDeadline.test.ts
+++ b/src/process/ProviderDeadline.test.ts
@@ -179,3 +179,25 @@ it("releases the timer and listener on dispose with a pending wait", async () =>
     vi.useRealTimers();
   }
 });
+
+// Preserve the authored fractional-clock control while following the current
+// owning deadline's re-arm contract for an early native timer callback.
+it("reports zero after the re-armed deadline reaches a fractional early callback", async () => {
+  vi.useFakeTimers({ toFake: ["setTimeout", "clearTimeout"] });
+  const now = vi.spyOn(performance, "now").mockReturnValue(1_000);
+  const deadline = new ProviderStartupDeadline(40);
+  try {
+    now.mockReturnValue(1_039.6);
+    await vi.advanceTimersByTimeAsync(40);
+    expect(deadline.signal.aborted).toBe(false);
+    expect(deadline.remainingMs()).toBe(1);
+    now.mockReturnValue(1_040);
+    await vi.advanceTimersByTimeAsync(1);
+    expect(deadline.signal.aborted).toBe(true);
+    expect(deadline.interruption).toBe("timeout");
+    expect(deadline.remainingMs()).toBe(0);
+  } finally {
+    deadline.dispose();
+    vi.useRealTimers();
+  }
+});
diff --git a/src/process/ProviderDeadline.ts b/src/process/ProviderDeadline.ts
index 83e24a807..7681ecf62 100644
--- a/src/process/ProviderDeadline.ts
+++ b/src/process/ProviderDeadline.ts
@@ -79,6 +79,9 @@ export class ProviderStartupDeadline {
 
   /** Milliseconds still available to the next startup phase. */
   remainingMs(): number {
+    // Node timers can fire a fraction of a millisecond before the monotonic
+    // deadline, so an elapsed timer must not report time left to spend.
+    if (this.#interruption === "timeout") return 0;
     return Math.max(0, Math.ceil(this.#deadlineAt - performance.now()));
   }
 
diff --git a/tests/boundary/cli/emptyHomeStartup.test.ts b/tests/boundary/cli/emptyHomeStartup.test.ts
new file mode 100644
index 000000000..f1c73734f
--- /dev/null
+++ b/tests/boundary/cli/emptyHomeStartup.test.ts
@@ -0,0 +1,32 @@
+import { readFile } from "node:fs/promises";
+
+import { expect } from "vitest";
+import { z } from "zod";
+
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+import { cliTest } from "../../support/cli/cliFixture.js";
+
+const packageSchema = z.object({ version: z.string() });
+
+// Node's Windows home lookup throws for an empty USERPROFILE, so a dependency
+// that resolves the home during import used to stop every command there.
+cliTest("starts when the selected home is empty", async ({ cli }) => {
+  const { version } = packageSchema.parse(
+    JSON.parse(await readFile("package.json", "utf8")),
+  );
+  const cwd = await createTestTempDirectory("rea-empty-home-startup-");
+  const environment = { HOME: "", USERPROFILE: "" };
+
+  const reported = await cli.run({
+    arguments: ["--version"],
+    cwd,
+    environment,
+  });
+  expect(reported.stderr).toBe("");
+  expect(reported.exitCode).toBe(0);
+  expect(reported.stdout.trim()).toBe(version);
+
+  const help = await cli.run({ arguments: ["--help"], cwd, environment });
+  expect(help.stderr).not.toContain("uv_os_homedir");
+  expect(help.exitCode).toBe(0);
+});