diff --git a/src/service.ts b/src/service.ts
index 43d4d8ffe..856fa4558 100644
--- a/src/service.ts
+++ b/src/service.ts
@@ -33,7 +33,7 @@ import {
   type ElevatedSchtasksCreateAndRunExecution,
   type ElevatedSchtasksCreateAndRunResult,
 } from "./lib/windows-elevation";
-import { defaultWinswEntry, installWinswService, startWinswService, stopWinswService, statusWinswRaw, uninstallWinswService, winswStatusSummary, winswXmlPath, WINSW_SERVICE_ID, WINSW_SHA256, WINSW_VERSION } from "./lib/winsw";
+import { defaultWinswEntry, installWinswService, startWinswService, stopWinswService, statusWinswRaw, uninstallWinswService, winswStatusSummary, winswXmlPath, WINSW_SERVICE_ID, WINSW_SHA256, WINSW_VERSION, type WinswStatus } from "./lib/winsw";
 import { hardenSecretDir, hardenSecretPath } from "./lib/windows-secret-acl";
 import { windowsEnvIndirectBatchPathList, windowsEnvIndirectBatchValue } from "./lib/win-paths";
 import { recordOwnedConfigPath } from "./lib/config-ownership";
@@ -2452,33 +2452,53 @@ function removeServiceInstallState(): void {
   }
 }
 
+type UninstallServiceHooksForTests = {
+  platform: typeof process.platform;
+  assertEnvironment: () => void;
+  probeWindowsTask: () => WindowsSchedulerTaskProbe;
+  uninstallWindowsTask: () => void;
+  nativeStatus: () => WinswStatus;
+  uninstallNative: () => void;
+  removeInstallState: () => void;
+};
+
+let uninstallServiceHooksForTests: UninstallServiceHooksForTests | null = null;
+
+/** Test-only hooks for full-uninstall service removal. */
+export function setUninstallServiceHooksForTests(hooks: UninstallServiceHooksForTests | null): void {
+  uninstallServiceHooksForTests = hooks;
+}
+
 /**
  * Best-effort service removal for full uninstall. Unlike `ocx service uninstall`, this is quiet
- * when no service exists and never exits the process just because the platform has no service
- * manager.
+ * when no service exists or the platform has no service manager. An installed native Windows
+ * service or scheduler task that cannot be removed throws so the caller cannot erase state and
+ * report success.
  */
 export function uninstallServiceIfInstalled(): boolean {
-  assertServiceEnvironmentMatchesInstall();
-  if (process.platform === "darwin") {
+  const hooks = uninstallServiceHooksForTests;
+  (hooks?.assertEnvironment ?? assertServiceEnvironmentMatchesInstall)();
+  const platform = hooks?.platform ?? process.platform;
+  if (platform === "darwin") {
     if (existsSync(plistPath())) {
       try { uninstallLaunchd(); removeServiceInstallState(); return true; } catch { return false; }
     }
-  } else if (process.platform === "win32") {
+  } else if (platform === "win32") {
     let removed = false;
-    try {
-      const q = schtasks(["/query", "/tn", TASK]);
-      if (q.includes(TASK)) { uninstallWindows(); removed = true; }
-    } catch { /* task not found */ }
-    if (statusWinswRaw() !== "nonexistent") {
-      try {
-        uninstallWinswService();
-        removed = true;
-      } catch (err) {
-        console.warn(`⚠️  Failed to remove native service: ${err instanceof Error ? err.message : String(err)}. Check 'sc.exe query ${WINSW_SERVICE_ID}'.`);
-      }
+    const scheduler = (hooks?.probeWindowsTask ?? probeWindowsSchedulerTask)();
+    if (scheduler.status === "unknown") {
+      throw new Error(`Could not determine Task Scheduler state: ${scheduler.detail}`);
+    }
+    if (scheduler.status === "present") {
+      (hooks?.uninstallWindowsTask ?? uninstallWindows)();
+      removed = true;
     }
-    if (removed) { removeServiceInstallState(); return true; }
-  } else if (process.platform === "linux" && existsSync(unitPath())) {
+    if ((hooks?.nativeStatus ?? statusWinswRaw)() !== "nonexistent") {
+      (hooks?.uninstallNative ?? uninstallWinswService)();
+      removed = true;
+    }
+    if (removed) { (hooks?.removeInstallState ?? removeServiceInstallState)(); return true; }
+  } else if (platform === "linux" && existsSync(unitPath())) {
     try { uninstallSystemd(); removeServiceInstallState(); return true; } catch {
       try { unlinkSync(unitPath()); removeServiceInstallState(); return true; } catch { return false; }
     }
@@ -2873,4 +2893,4 @@ export async function serviceCommand(...args: (string | undefined)[]): Promise<v
       console.error("       --native (Windows only): register a real SCM service via WinSW instead of Task Scheduler.");
       process.exit(1);
   }
-}
\ No newline at end of file
+}
diff --git a/tests/uninstall.test.ts b/tests/uninstall.test.ts
index b09dbc75e..8f9b9749b 100644
--- a/tests/uninstall.test.ts
+++ b/tests/uninstall.test.ts
@@ -1,4 +1,8 @@
-import { describe, expect, test } from "bun:test";
+import { afterEach, describe, expect, test } from "bun:test";
+import {
+  setUninstallServiceHooksForTests,
+  uninstallServiceIfInstalled,
+} from "../src/service";
 
 const root = new URL("../", import.meta.url);
 
@@ -7,6 +11,8 @@ async function readText(path: string): Promise<string> {
 }
 
 describe("full uninstall command", () => {
+  afterEach(() => setUninstallServiceHooksForTests(null));
+
   test("CLI exposes a one-shot local state cleanup command", async () => {
     const cli = await readText("src/cli/index.ts");
 
@@ -41,6 +47,43 @@ describe("full uninstall command", () => {
     expect(service).toContain("uninstallSystemd");
   });
 
+  test("native service removal failure propagates without deleting install state", () => {
+    const calls: string[] = [];
+    let stateRemovals = 0;
+    setUninstallServiceHooksForTests({
+      platform: "win32",
+      assertEnvironment: () => {},
+      probeWindowsTask: () => ({ status: "present" }),
+      uninstallWindowsTask: () => { calls.push("scheduler"); },
+      nativeStatus: () => "started",
+      uninstallNative: () => {
+        calls.push("native");
+        throw new Error("native removal failed");
+      },
+      removeInstallState: () => { stateRemovals++; },
+    });
+
+    expect(() => uninstallServiceIfInstalled()).toThrow("native removal failed");
+    expect(calls).toEqual(["scheduler", "native"]);
+    expect(stateRemovals).toBe(0);
+  });
+
+  test("scheduler removal failure propagates without deleting install state", () => {
+    let stateRemovals = 0;
+    setUninstallServiceHooksForTests({
+      platform: "win32",
+      assertEnvironment: () => {},
+      probeWindowsTask: () => ({ status: "present" }),
+      uninstallWindowsTask: () => { throw new Error("scheduler removal failed"); },
+      nativeStatus: () => "nonexistent",
+      uninstallNative: () => {},
+      removeInstallState: () => { stateRemovals++; },
+    });
+
+    expect(() => uninstallServiceIfInstalled()).toThrow("scheduler removal failed");
+    expect(stateRemovals).toBe(0);
+  });
+
   test("full uninstall kills the tracked proxy before deleting service assets", async () => {
     const cli = await readText("src/cli/index.ts");
     const uninstallBody = cli.slice(cli.indexOf("async function handleUninstall()"), cli.indexOf("type HealthCheck"));