fix(desktop): suppress console window flashes from background spawns on Windows

desktop/src-tauri/src/commands/agent_auth.rs

@@ -194,6 +194,12 @@ fn run_buzz_acp_auth_command_with_paths<const N: usize>(
     if let Some(path) = augmented_path {
         command.env("PATH", path);
     }
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
 
     command
         .output()
@@ -226,11 +232,19 @@ fn run_claude_subscription_login(runtime_id: &str, method: &AcpAuthMethod) -> Re
     let (command, args) = argv
         .split_first()
         .ok_or_else(|| "Claude login command is empty".to_string())?;
-    let status = Command::new(command)
+    let mut login = Command::new(command);
+    login
         .args(args)
         .stdin(Stdio::null())
         .stdout(Stdio::null())
-        .stderr(Stdio::null())
+        .stderr(Stdio::null());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        login.creation_flags(CREATE_NO_WINDOW);
+    }
+    let status = login
         .status()
         .map_err(|error| format!("failed to run Claude login: {error}"))?;
     if !status.success() {

desktop/src-tauri/src/commands/agent_discovery/managed_node.rs

@@ -93,12 +93,19 @@ fn managed_node_runtime_ready() -> bool {
     if !node.is_file() {
         return false;
     }
-    let output = std::process::Command::new(&node)
+    let mut command = std::process::Command::new(&node);
+    command
         .arg("--version")
         .stdin(std::process::Stdio::null())
         .stdout(std::process::Stdio::piped())
-        .stderr(std::process::Stdio::null())
-        .output();
+        .stderr(std::process::Stdio::null());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
+    let output = command.output();
     output
         .ok()
         .filter(|output| output.status.success())

desktop/src-tauri/src/commands/agent_model_process.rs

@@ -49,6 +49,12 @@ pub(super) async fn run_agent_models_command(
             cmd.env(k, v);
         }
         crate::managed_agents::configure_runtime_cli(&mut cmd, known_acp_runtime(&agent_command));
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+            cmd.creation_flags(CREATE_NO_WINDOW);
+        }
         cmd.stdout(std::process::Stdio::piped())
             .stderr(std::process::Stdio::piped())
             .output()

desktop/src-tauri/src/commands/media_transcode.rs

@@ -24,6 +24,12 @@ fn ffmpeg_command(path: &std::path::Path) -> std::process::Command {
     for (name, value) in required_windows_env {
         command.env(name, value);
     }
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
     command
 }
 
@@ -576,7 +582,8 @@ mod tests {
         };
         let source =
             std::env::temp_dir().join(format!("buzz-metadata-test-{}.mp4", uuid::Uuid::new_v4()));
-        let generated = std::process::Command::new(&ffmpeg)
+        let mut generate = std::process::Command::new(&ffmpeg);
+        generate
             .args(["-y", "-loglevel", "error", "-f", "lavfi", "-i"])
             .arg("testsrc2=size=64x64:rate=1")
             .args([
@@ -589,9 +596,14 @@ mod tests {
                 "-metadata:s:v:0",
                 "title=private camera stream",
             ])
-            .arg(&source)
-            .output()
-            .expect("run ffmpeg fixture generation");
+            .arg(&source);
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+            generate.creation_flags(CREATE_NO_WINDOW);
+        }
+        let generated = generate.output().expect("run ffmpeg fixture generation");
         if !generated.status.success() {
             eprintln!("skipping metadata round-trip: ffmpeg cannot encode H.264");
             let _ = std::fs::remove_file(&source);
@@ -623,12 +635,19 @@ mod tests {
         // Generate a small HEIC test image from a synthetic color source.
         let heic_path =
             std::env::temp_dir().join(format!("buzz-test-{}.heic", uuid::Uuid::new_v4()));
-        let gen = std::process::Command::new(&ffmpeg)
+        let mut generate = std::process::Command::new(&ffmpeg);
+        generate
             .args(["-y", "-loglevel", "error", "-f", "lavfi", "-i"])
             .arg("color=c=red:s=64x64:d=1")
             .args(["-frames:v", "1"])
-            .arg(&heic_path)
-            .output();
+            .arg(&heic_path);
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+            generate.creation_flags(CREATE_NO_WINDOW);
+        }
+        let gen = generate.output();
 
         let gen = match gen {
             Ok(o) if o.status.success() && heic_path.exists() => o,

desktop/src-tauri/src/commands/project_git_exec.rs

@@ -80,6 +80,12 @@ pub(crate) fn run_git(
     command.stdin(Stdio::null());
     command.stdout(Stdio::piped());
     command.stderr(Stdio::piped());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
 
     let mut child = command
         .spawn()

desktop/src-tauri/src/commands/relay_reconnect.rs

@@ -55,12 +55,18 @@ fn run_with_timeout(
     argv: &[String],
     timeout: std::time::Duration,
 ) -> Result<std::process::Output, String> {
-    let mut child = std::process::Command::new(&argv[0])
+    let mut command = std::process::Command::new(&argv[0]);
+    command
         .args(&argv[1..])
         .stdout(std::process::Stdio::piped())
-        .stderr(std::process::Stdio::null())
-        .spawn()
-        .map_err(|e| format!("spawn failed: {e}"))?;
+        .stderr(std::process::Stdio::null());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
+    let mut child = command.spawn().map_err(|e| format!("spawn failed: {e}"))?;
 
     let deadline = std::time::Instant::now() + timeout;
     loop {

desktop/src-tauri/src/managed_agents/agent_env.rs

@@ -119,6 +119,12 @@ mod tests {
         let mut cmd = std::process::Command::new("env");
         cmd.env_clear();
         build_buzz_agent_provider_defaults(&mut cmd);
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+            cmd.creation_flags(CREATE_NO_WINDOW);
+        }
         let output = cmd.output().expect("env should run");
         let stdout = String::from_utf8_lossy(&output.stdout);
         assert!(
@@ -229,6 +235,12 @@ mod tests {
         cmd.env("BUZZ_AGENT_PROVIDER", "databricks");
         // Simulate what runtime_metadata_env_vars writes from the record (comes after).
         cmd.env("BUZZ_AGENT_PROVIDER", "anthropic");
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+            cmd.creation_flags(CREATE_NO_WINDOW);
+        }
         let output = cmd.output().expect("env should run");
         let stdout = String::from_utf8_lossy(&output.stdout);
         assert!(

desktop/src-tauri/src/managed_agents/backend.rs

@@ -30,10 +30,16 @@ pub fn invoke_provider(
     if let Some(home) = super::default_agent_workdir() {
         cmd.current_dir(home);
     }
-    let mut child = cmd
-        .stdin(std::process::Stdio::piped())
+    cmd.stdin(std::process::Stdio::piped())
         .stdout(std::process::Stdio::piped())
-        .stderr(std::process::Stdio::piped())
+        .stderr(std::process::Stdio::piped());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        cmd.creation_flags(CREATE_NO_WINDOW);
+    }
+    let mut child = cmd
         .spawn()
         .map_err(|e| format!("failed to spawn {}: {e}", binary.display()))?;
 

desktop/src-tauri/src/managed_agents/discovery.rs

@@ -677,7 +677,15 @@ fn login_shell_candidates() -> Vec<PathBuf> {
 /// Returns trimmed stdout if the command succeeds with non-empty output.
 fn run_in_login_shell(args: &[&str]) -> Option<String> {
     for shell in login_shell_candidates() {
-        let Ok(output) = Command::new(&shell).args(args).output() else {
+        let mut command = Command::new(&shell);
+        command.args(args);
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+            command.creation_flags(CREATE_NO_WINDOW);
+        }
+        let Ok(output) = command.output() else {
             continue;
         };
         if !output.status.success() {
@@ -916,6 +924,12 @@ fn probe_auth_status(binary_path: &Path, probe_args: &[&str]) -> AuthStatus {
         .stdin(std::process::Stdio::null())
         .stdout(std::process::Stdio::piped())
         .stderr(std::process::Stdio::piped());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
 
     let mut child = match command.spawn() {
         Ok(c) => c,
@@ -1079,6 +1093,12 @@ pub(crate) fn probe_codex_acp_major_version_with_path(
     if let Some(path) = augmented_path {
         command.env("PATH", path);
     }
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        command.creation_flags(CREATE_NO_WINDOW);
+    }
     let mut child = command
         .stdout(tmp.try_clone().ok()?)
         .stderr(std::process::Stdio::null())