diff --git a/README.md b/README.md
index 59c855d8..7a030de2 100644
--- a/README.md
+++ b/README.md
@@ -240,7 +240,7 @@ just dev     # starts backend + desktop app
 
 Install [just](https://github.com/casey/just): `brew install just` or `cargo install just`. Run `just --list` to see all commands.
 
-**Prerequisites:** [Bun](https://bun.sh), [Rust](https://rustup.rs), [Python 3.11+](https://python.org), [Tauri Prerequisites](https://v2.tauri.app/start/prerequisites/), and [XCode](https://developer.apple.com/xcode/) on macOS.
+**Prerequisites:** [Bun](https://bun.sh), [Rust](https://rustup.rs), [Python 3.11+](https://python.org), [Tauri Prerequisites](https://v2.tauri.app/start/prerequisites/), and [Xcode](https://developer.apple.com/xcode/) on macOS.
 
 ### Platform Notes
 
diff --git a/backend/server.py b/backend/server.py
index 2cf6d212..573b5081 100644
--- a/backend/server.py
+++ b/backend/server.py
@@ -161,6 +161,9 @@ if __name__ == "__main__":
         )
         args = parser.parse_args()
 
+        if args.parent_pid is not None and args.parent_pid <= 0:
+            parser.error("--parent-pid must be a positive integer")
+
         # Detect backend variant from binary name
         # voicebox-server-cuda → sets VOICEBOX_BACKEND_VARIANT=cuda
         import os
diff --git a/justfile b/justfile
index 9788123a..7595ca3c 100644
--- a/justfile
+++ b/justfile
@@ -194,6 +194,7 @@ build-server: _ensure-venv
     & "{{ python }}" backend/build_binary.py; \
     if ($LASTEXITCODE -ne 0) { throw "build_binary.py failed with exit code $LASTEXITCODE" }; \
     $triple = (rustc --print host-tuple); \
+    New-Item -ItemType Directory -Path "{{ tauri_dir }}/src-tauri/binaries" -Force | Out-Null; \
     Copy-Item "backend/dist/voicebox-server.exe" "{{ tauri_dir }}/src-tauri/binaries/voicebox-server-$triple.exe" -Force; \
     Write-Host "Copied sidecar: voicebox-server-$triple.exe"