diff --git a/packages/cli/src/__tests__/preload.ts b/packages/cli/src/__tests__/preload.ts
index 7251c247d..9e229afec 100644
--- a/packages/cli/src/__tests__/preload.ts
+++ b/packages/cli/src/__tests__/preload.ts
@@ -60,6 +60,10 @@ cleanupStrayTestFiles();
 
 const TEST_HOME = mkdtempSync(join(tmpdir(), "spawn-test-home-"));
 
+// Disable telemetry in tests to prevent fire-and-forget fetch calls from
+// interfering with other test files' global.fetch mocks.
+process.env.SPAWN_TELEMETRY = "0";
+
 // Redirect all user-directory env vars to the isolated temp
 process.env.HOME = TEST_HOME;
 process.env.XDG_CACHE_HOME = join(TEST_HOME, ".cache");
diff --git a/packages/cli/src/shared/telemetry.ts b/packages/cli/src/shared/telemetry.ts
index f9d45dde4..3c458142b 100644
--- a/packages/cli/src/shared/telemetry.ts
+++ b/packages/cli/src/shared/telemetry.ts
@@ -242,6 +242,11 @@ export function captureError(type: string, err: unknown): void {
 
 /** Send a single event to PostHog immediately. Fire-and-forget. */
 function sendEvent(event: string, properties: Record<string, unknown>): void {
+  // Re-check at send time — guards against singleton state leaking in tests
+  // where initTelemetry() was called with _enabled=true but env was later restored.
+  if (process.env.BUN_ENV === "test" || process.env.NODE_ENV === "test" || process.env.SPAWN_TELEMETRY === "0") {
+    return;
+  }
   const body = JSON.stringify({
     api_key: POSTHOG_TOKEN,
     batch: [