diff --git a/.Jules/sentinel.md b/.Jules/sentinel.md
index 70f67594..5de2fc05 100644
--- a/.Jules/sentinel.md
+++ b/.Jules/sentinel.md
@@ -18,3 +18,7 @@
 **Vulnerability:** The application was falling back to storing OBS passwords as plaintext strings inside exported/saved JSON models (`Macro.swift` and `SystemCommand.swift`) if saving to the macOS Keychain failed.
 **Learning:** Saving secrets to unencrypted formats simply because secure storage fails is a critical anti-pattern known as "failing open" that results in data exposure.
 **Prevention:** Always fail securely. If secure storage operations fail, discard the sensitive credential in memory rather than writing it insecurely to disk, even if it requires the user to re-authenticate later.
+## 2026-06-26 - [Denial of Service via Pipe Deadlock]
+**Vulnerability:** The application executed `Foundation.Process` shell commands and waited for them to exit (`process.waitUntilExit()`) before attempting to read the standard output and error pipes.
+**Learning:** If a child process writes more data than the operating system's pipe buffer can hold (typically ~64KB), the child process will block waiting for the parent to read the data. If the parent is blocked on `waitUntilExit()`, a deadlock occurs, resulting in a Denial of Service.
+**Prevention:** Always read data from process pipes (e.g., using `fileHandleForReading.readDataToEndOfFile()`) *before* calling `process.waitUntilExit()` to ensure the pipe buffer is drained and the child process can finish executing. However, ensure that this fix does not introduce deadlocks when used with handlers like `readabilityHandler` or processes that don't close their streams until parent exit.
diff --git a/XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift b/XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift
index 40e97b37..15ecd7cb 100644
--- a/XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift
+++ b/XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift
@@ -1405,10 +1405,9 @@ final class UniversalControlMouseRelay: @unchecked Sendable {
             NSLog("[UCMouseRelay] Could not run tailscale status: %@", String(describing: error))
             return []
         }
+        let data = pipe.fileHandleForReading.readDataToEndOfFile()
         process.waitUntilExit()
         guard process.terminationStatus == 0 else { return [] }
-
-        let data = pipe.fileHandleForReading.readDataToEndOfFile()
         guard let object = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
               let peers = object["Peer"] as? [String: Any] else {
             return []